Dissertations / Theses: 'Mesoporou'

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Gallo, Jean Marcel Ribeiro. "Síntese de carbonos cerâmicos mesoporosos para aplicação como eletrodos em células a combustível a metanol direto." [s.n.], 2010. http://repositorio.unicamp.br/jspui/handle/REPOSIP/250419.

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Orientadores: Heloise de Oliveira Pastore, Leonardo Marchese
Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Química
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Resumo: Esse trabalho teve como objetivo a aplicação de peneiras moleculares mesoporosas de sílica como suporte para metal em aplicações em eletrodos na Célula a combustível a metanol direto (DMFC). As peneiras moleculares mais importantes, MCM-41, MCM-48 e SBA-15, foram escolhidas. Em um primeiro momento a reprodutibilidade das sínteses foi verificada. Como pesquisa lateral foi estudada a acidez de superfície da SBA-15 contendo alumínio obtida por síntese direta. Além disso, foi desenvolvida a primeira síntese direta para a [Al]-SBA-15 Sílica é um isolante elétrico e, portanto, não pode ser utilizada como um eletrodo, deste modo, uma nova família de compósitos chamada Carbonos Cerâmicos Mesoporosos (MCC) foi preparada pela adição de grafite comercial na síntese das sílicas mesoporosas (MCM-41, MCM-48 ou SBA-15). A grafite não influenciou na formação da mesofase de sílica, de qualquer maneira, a MCC-MCM-41 e a MCC-MCM-48 cresceram na superfície da grafite. As MCCs preparadas com razão em massa sílica/carbono de 1/1 e 1/1.25 apresentaram condutividades elétricas similares enquanto MCCs com menos quantidade de carbono se mostraram isolantes elétricos. As MCCs(1/1) modificadas com 20 % em massa de paládio foram usadas na DMFC chegando no máximo a desempenhos 10 vezes menores que o do sistema usando o suporte comercia Vulcan XC-72R. Esse comportamento foi atribuida a menos condutividade elétrica dos MCCs. Para aumentar a condutividade elétrica dos MCCs(1/1), o agente direcionador orgânico usado na síntese da fase silícica foi carbononizado ( ao invez de calcinado, como feito anteriormente) Alternativamente, os MCCs foram sintetizados com uma razão em massa sílica/carbono de 1/3. Os testes dos MCCs contendo 20 % em massa de platina no cátodo da DMFC mostraram melhores resultados para a MCC-SBA-15(1/3) e a MCC-MCM-48(1/1) pirolisada. Por outro lado, o despenho do sistema usando o suporte Vulcan-XC-72R foi o dobro. Modificados com 60 % em massa da liga PtRu, o MCC-SBA-15(1/3) e o MCC-MCM-48(1/1) pirolisado foram aplicados no ânodo da DMFC, alcançando desempenhos 20 e 40 % maiores que a Vulcan XC-72R.
Abstract: The present work aimed at using mesoporous silica as metal support for Direct Methanol Fuel Cell (DMFC) electrodes. The most important mesoporous silica, MCM-41, MCM-48 and SBA-15, were chosen. In a first moment their synthesis were verified with respect to the reproductibility. As side results, the surface acidity of aluminum containing SBA-15 obtained by direct synthesis was also studied and it is also reported the first [Al]-SBA-16 obtained by direct synthesis was reported. Silica is electrically insulating and thus cannot be used directly in a cell electrode, thus it was reported here the preparation of the novel composite named Mesoporous Carbon Ceramics (MCC) obtained by the addition of commercial graphite into the mesoporous silica synthesis (MCM-41, MCM-48 or SBA-15). The graphite did not influence in the formation of the silica mesophase, however, MCC-MCM-41 and MCC-MCM-48 grow on the graphite surface. The MCCs prepared with silica/carbon weight ratio of 1/1 and 1/1.25 presented similar electrical conductivities while lower carbon loading MCCs were found insulating. The MCCs(1/1) modified with 20 wt % of platinum were used on Direct Methanol Fuel Cell electrodes (DMFC) reaching performances more ten 10 times lower than that of a system using the commercial metal support Vulcan XC-72R, probably due to their lower electrical conductivity. To increase the electrical conductivity of the MCCs(1/1), the surfactant used to synthesize the silica phase was carbonized (instead of calcined as done for the previous materials). Alternatively, MCCs was synthesized with silica/carbon weight ratio of 1/3. The test of 20 wt. % platinum-containing MCCs on the cathode of the DMFC showed that the best results were obtained for the MCC-SBA-15(1/3) and for the template-pyrolysed MCC-MCM-48(1/1), however, the performance was approximately half of that of the system using Vulcan-XC-72R. When modified with 60 wt % of PtRu alloy, MCC-SBA-15(1/3) and to the template-pyrolysed MCC-MCM-48(1/1) and applied on the DMFC anode, the performances at 343 K was ca. 20 and 40 % higher that that obtained for the system using Vulcan XC-72R.
Doutorado
Quimica Inorganica
Doutor em Ciências

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Moscofian, Andrea Sales de Oliveira. "Filossilicatos de magnesio e silicas mesoporosas organofuncionalizados para o uso na remoção de corantes industriais." [s.n.], 2009. http://repositorio.unicamp.br/jspui/handle/REPOSIP/250079.

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Orientador: Claudio Airoldi
Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Quimica
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Resumo: Filossilicatos de magnésio e sílicas mesoporosas, com grupos orgânicos ligados às estruturas poliméricas inorgânicas, foram estudados na remoção de corantes. Para a síntese dos materiais nanoestruturados organofuncionalizados foram empregados agentes sililantes, (H3CO)3Si-R1, em que R1 é a cadeia carbônica contendo grupos funcionais: 3-aminopropiltrimetoxissilano, cloreto de octadecildimetil(3-trimetoxissilil-propil)amônio, 3-mercaptopropiltrimetoxissilano, 3-etilenodiaminopropiltrimetoxissilano e 3-dietilenotriaminopropiltrimetoxissilano. Através do processo sol-gel foram obtidos filossilicatos com estruturas inorgânicas similares àquelas dos silicatos lamelares naturais e sílicas mesoporosas empregando-se o surfatante CTAB como direcionador da estrutura inorgânica. As moléculas pendentes nos poros dos novos materiais com cargas positivas ou protonadas interagiram com as cargas negativas dos corantes utilizados na indústria têxtil: amarelo reativo GR, vermelho reativo RB e azul reativo RN. O estudo de adsorção mostrou que o filossilicato contendo cloreto de octadecildimetil(3-trimetoxissilil-propil)amônio, Fil-COTA, foi o material que apresentou a maior capacidade de adsorção, 1343 mg gpara o corante amarelo GR, 1286 mg g para o azul reativo RN e 344 mg gpara o vermelho reativo RB. Também foram realizados testes em amostras reais de efluente têxtil. Os resultados mostraram que não é necessário ajustar o pH inicial, a saturação do material ocorre após 3 h, sendo necessária uma massa mínima de 2,5 g dm de Fil-COTA. Portanto, este material é promissor no tratamento de efluentes têxteis reais.
Abstract: Magnesium phyllosilicates and mesoporous silicas, with organic groups anchored onto an inorganic polymeric backbones were studied for dye removal. In the synthesis of the organofunctionalized nanostructured materials, the silylanting agents, (H3CO)3Si-R1, where R1 represents carbonic chain containing functional groups: 3-aminopropyltrimethoxysilane, octadecyl (3-trimethoxysylilpropyl)ammonium chloride, 3 ¿ mercaptopropyltri-methoxysilane, 3-ethylenediaminetrymethoxysilane and 3-diethy-lenetriaminetrymethoxysilane were employed. The sol-gel process was used and phyllosilicates with inorganic lamellar structures similar to those of natural silicate and mesoporous silicas were obtained using the surfactant CTAB as template to direct inorganic structure in the latter case. The pendent molecules in pores of the new material with positive charge interact with the negative charge of the dyes used in the textile industry: reactive yellow GR, reactive red RB and reactive blue RN. The adsorption study showed that the phyllosilicate containing octadecyldimethyl(3-trimethoxysilylpropyl)ammonium chloride, Fil-COTA, presented the highest adsorption capacity, 1343 mg g for reactive yellow GR, 1286 mg g for reactive blue RN and 344 mg g for reactive red RB. Real samples of textile effluents were also tested. The results showed that it is not necessary to ajust the inicial pH, surface saturation occurs after 3 h and the minimum mass necessary is 2,5 g dm of Fil-COTA. Thus, this is a promising material for textile effluent treatement.
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Quimica Inorganica
Doutor em Ciências

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Badshah, Syed. "Híbridos inorgânico-orgânicos nanoestruturados de sílica mesoporosa e filossilicatos - energética da remoção de cátions na interface sólido/líquido." [s.n.], 2011. http://repositorio.unicamp.br/jspui/handle/REPOSIP/250054.

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Orientador: Claudio Airoldi
Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Química
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Resumo: No presente trabalho, híbridos inorgânico-orgânicos nanoestruturados de sílica mesoporosa e de filossilicatos de magnésio lamelares com estrutura similar ao talco foram sintetizados e caracterizados. A máxima capacidade sorptiva de cátions dos híbridos e as características energéticas das interações dos cátions com centros básicos, na interface sólido/líquido, foram também estudadas. A sílica mesoporosa análoga aos materiais SBA-15 tem sido sintetizada por meio do tribloco co-polímero EO20-PO70 -EO20 (P123 - Pluronic®), que atua como um agente direcionador estrutural. Os materiais SBA-15 sintetizados foram funcionalizados com vários agentes sililantes, os quais apresentam os seguintes grupos funcionais: amida, nitrila e marfolina ou base de Schiff do anel tiofênico. Os agentes sililantes com os grupos funcionais mencionados acima foram sintetizados por meio de reações de adição de Michael do aceptor de Michael a,b - insaturado (acrilamida, acrilonitrila e 4- acriloilmarfolina), ou por meio da reação de base de Schiff do 2-tiofenocaboxaldeído com os agentes sililantes aminados, comercialmente disponíveis. As técnicas de espalhamento de raios X a baixa ângulo (SAXS) e de adsorção/desorção de nitrogênio para a SBA-15 pura e a SBA-15 funcionalizada mostraram um arranjo estrutural hexagonal bem-ordenado nos materiais. Os filossilicatos lamelares híbridos com diferentes porções orgânicas presentes dentro dos nanoespaços lamelares foram sintetizados por meio de reações sol-gel de uma única etapa. Com esse intuito, os agentes sililantes com vários grupos funcionais (tiopropanamida, tiocarbamato, nitrila e base de Schiff ou anel tiofênico) foram sintetizados e reagiram com uma solução metanólica de nitrato de magnésio, sob condições básicas. A difratometria de raios X indicou distâncias basais maiores de que 1 nm para os filossilicatos híbridos sintéticos. A técnica de difração de raios X também mostrou que a estrutura inorgânica dos filossilicatos híbridos era similar àquela do talco natural. A estrutura inorgânica do filossilicato híbrido é composta de camadas octaédricas ocupadas pelo átomo de magnésio hexacoordenado presentes entre duas camadas tetraédricas silícicas, em que a porção orgânica está covalentemente ligada à camada tetraédrica da estrutura em camadas. A integridade das porções orgânicas ligadas à rede inorgânica da sílica mesoporosa ou dos filossilicatos foi confirmada por meio da Espectroscopia no Infravermelho com transformada de Fourier e por meio da técnica de Ressonância Magnética no estado sólido para os núcleos Si e C. A máxima incorporação de porções orgânicas foi determinada por meio da análise elementar. As porções orgânicas ligadas aos materiais híbridos contêm: nitrogênio, oxigênio e enxofre, os quais correspondem aos sítios básicos disponíveis para a remoção de espécies como: Pb, Cu, Cd e Ni. As capacidades sorptivas máximas dos materiais híbridos para tais cátions foram obtidas por meio de Isotermas de adsorção de Langmuir. Os resultados revelam que os filossilicatos lamelares híbridos apresentam elevada capacidade para remoção de cátions em comparação com os materiais SBA-15, devido ao elevado grau de funcionalização. A energética das interações entre os cátions e os centros básicos ao longo da interface sólido/líquido foram determinadas através da microcalorimetria. As variações negativas da energia de Gibbs, de entalpia e os valores positivos de variação entrópica indicam interações espontâneas e favoráveis entre os sólidos e os íons metálicos. Esses resultados favoráveis indicam que os híbridos sintetizados podem ser úteis na remoção de cátions tóxicos de soluções aquosas, auxiliando na despoluição de ecossistemas
Abstract: In the present work, nanostructured inorganic-organic hybrids based on mesoporous silica and lamellar magnesium phyllosilicates with talc-like structure were synthesized and characterized. The maximum cations sorption capacity of the hybrids and energetic features from cation- basic center interactions at the solid liquid interface were also studied. The mesoporous silica analogous to SBA-15 materials has been synthesized through the triblock co-polymer EO20-PO70 -EO20 (P123 ¿ Pluronic®) as a structured directing agent. The synthesized SBA-15 materials were functionalized with various silylating agents having organic functional groups of amide, nitrile, and marpholine or Schiff base of thiophenic ring. The silylating agents with the aforementioned functional groups were synthesized either by the Michael addition reactions of a,b-unsaturated Michael acceptor (acrylamide, acrylonitrile and 4-acryloylmarpholine) or by the Schiff base reaction of 2-thiophenecaboxaldehyde with commercially available aminated silylating agents. Small angle X-ray scattering (SAXS) and nitrogen adsorption/desorption experiments for both SBA-15 and functionalized SBA-15 showed well-ordered hexagonal array structure. The lamellar phyllosilicates hybrids with different organic moieties inside the lamellar nanospaces were synthesized through a single step sol-gel reaction. For this purpose, silylating agents with various functional groups (thiopropanamide, thiocarbamate, nitrile and Schiff base of thiophenic ring) were synthesized and reacted with methanolic solution of magnesium nitrate under basic conditions. The X-ray diffraction showed basal distances of more than 1 nanometer for the synthetic hybrid phyllosilicates. The XRD also showed that the inorganic structure of the hybrid phyllosilicates was similar to that of natural talc. The inorganic network of the hybrid phyllosilicate is composed of octahedral sheet occupied by hexacoordinated magnesium atom sandwiched between two tetrahedral silicic sheets, and the organic moiety is covalently bonded to the tetrahedral sheet of the layered structure. The integrity of organic moieties attached to the inorganic network of mesoporous silica or phyllosilicates was confirmed by the Fourier transform infrared spectroscopy and nuclear magnetic resonance in the solid-state for the Si and C nuclei. The maximum incorporation of organic moieties was determined through elemental analysis. The attached organic moieties of the hybrid materials contain nitrogen, oxygen or sulfur basic centers available for divalent lead, copper, cadmium and nickel cation removal. The maximum sorption capacities of the hybrids for such cations were obtained through Langmuir adsorption isotherms. The results reveal that the lamellar magnesium phyllosilicate hybrids present high capacity for cations removal as compared to functionalized SBA-15 materials, due to a high degree of functionalization. The energetic of cation-basic centers interactions at the solid/liquid interface were determined through microcalorimetry. The negative Gibbs energy, exothermic enthalpy and positive entropic values indicate spontaneous and favorable interactions between the solids and metal ions. These favorable results indicated that the synthesized hybrids can be useful for removal of toxic cations from aqueous solutions for the improvement of ecosystem
Doutorado
Quimica Inorganica
Doutor em Ciências

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Valente, Tain? Dias. "S?ntese da mordenita a partir da Al-SBA-15." Universidade Federal Rural do Rio de Janeiro, 2015. https://tede.ufrrj.br/jspui/handle/jspui/1352.

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In the present dissertation it was conducted the study of the synthesis of mesoporous molecular sieve Al-SBA-15 by direct synthesis in agitated reactor having the following molar ratio: 14 SiO2: 1 Al2O3: 0.235 P123: 1800 H2O. Initially, a study was done to optimize the synthesis of Al-SBA-15. Through this study, it was found that the operating conditions that resulted in the SBA-15 sample with a higher degree of ordering were gel aging time equal to 15 hours at 40 ? C and then at 100 ? C for 8 hours. These optimal conditions were used to perform scaling up to 5 gallon reactor. Samples of Al-SBA-15 were subjected to carbonization in order to fill the pores of SBA-15 with carbonaceous material and prevent the collapse of its structure. The carbonized samples were used as a source of silica for the synthesis of mordenite in dry medium using the transmission technique in the vapor phase (VPT). The purpose of this procedure was to obtain the mordenite having mesopores. For the preparation of the mordenite by VPT, several conditions were used, varying the synthesis time and form of addition of the reactants, presence or absence of an organic driver. The samples were characterized by X-ray and nitrogen adsorption. It was observed that in most of the experiments, there was no formation of mordenite phase. In the experiments in this phase was obtained, there was no significant mesoporosity training. Apparently, the presence of carbonaceous material was not sufficient to preserve the mesoporous structure of SBA-15. Key
No presente trabalho foi realizado o estudo da s?ntese da peneira molecular mesoporosa Al-SBA-15 a partir da s?ntese direta em reator agitado apresentando a seguinte propor??o molar: 14 SiO2: 1 Al2O3: 0,235 P123: 1800 H2O. Inicialmente, foi feito um estudo visando otimizar a s?ntese da Al-SBA-15. Atrav?s deste estudo, foi verificado que as condi??es operacionais que resultaram na amostra de SBA-15 com maior grau de ordenamento foram com tempo de envelhecimento do gel de s?ntese igual a 15 horas a 40?C e depois a 100?C por 8 horas. Estas condi??es otimizadas foram utilizadas para efetuar o aumento de escala para o reator de 5 gal?es. As amostras de Al-SBA-15 foram submetidas a carboniza??o com o objetivo de preencher os poros da SBA-15 com material carbon?ceo e evitar o colapso de sua estrutura. As amostras carbonizadas foram utilizadas como fonte de s?lica para a s?ntese da mordenita em meio seco utilizando a t?cnica de transporte em fase vapor (VPT). O objetivo deste procedimento foi a obten??o de mordenita tendo mesoporos. Para o preparo da mordenita por VPT, v?rias condi??es foram utilizadas, variando o tempo de s?ntese e forma de adi??o dos reagentes, presen?a ou aus?ncia de um direcionador org?nico. As amostras obtidas foram caracterizadas por difra??o de raios X e adsor??o de nitrog?nio. Foi observado que na maioria dos experimentos n?o houve a forma??o da fase mordenita. Nos experimentos em que esta fase foi obtida, n?o foi observada forma??o de mesoporosidade significativa. Aparentemente, a presen?a de material carbon?ceo n?o foi suficiente para preservar a estrutura mesoporosa da SBA-15. Palavras chave:

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Grecco, Saulo de Tarso Figueiredo. "Preparação de zeólitas mordenita com estrutura hierárquica de poros." Instituto de Química, 2013. http://repositorio.ufba.br/ri/handle/ri/16481.

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As restrições difusionais aos reagentes, causadas pelos microporos, limitam o uso das zeólitas no processamento de moléculas pesadas. Isto demanda o desenvolvimento de materiais que combinem as propriedades de zeólitas com as de materiais mesoporosos. Um número significativo de procedimentos experimentais, pré ou pós síntese, vem sendo sugerido para a obtenção de zeólitas hierarquicamente estruturadas. As metodologias de síntese mais bem sucedidas envolvem o uso de agentes geradores de mesoporosidade (agentes orgânicos e nanopartículas) ou nanomoldes (moldagem em nanoespaços), que geram sólidos com mesoporosidade intracristalina com uma estreita distribuição de tamanho de poros; isto resulta em sólidos contendo mesoporos, além dos microporos intrínsecos das zeólitas. Entretanto, ainda não existem estudos sistemáticos, que permitam estabelecer o efeito das variáveis de preparação sobre as características dos sólidos finais. A fim de superar essa dificuldade, neste trabalho foi estudado o efeito do tempo e da temperatura de cristalização do gel de síntese sobre as características de materiais baseados em mordenita com estrutura hierárquica de poros. Na preparação das amostras, adicionou-se um organossilano gerador de mesoporosidade (TPOAC, cloreto de [3- (trimetoxissilil)propil]octadecildimetilamônio), ao gel de síntese da mordenita, que foi cristalizado por diferentes períodos e em distintas temperaturas. Os sólidos obtidos foram submetidos à troca iônica com cloreto de amônio e posterior calcinação, de modo a obter a forma ácida do material. As amostras foram caracterizadas por termogravimetria, espectroscopia no infravermelho com transformada de Fourier, difração de raios X, análise textural por adsorção de nitrogênio, ressonância magnética nuclear de 29Si e de 27Al, microscopia eletrônica de varredura e medidas de acidez por dessorção de amônia à temperatura programada. Observou-se que a formação da mordenita contendo mesoporos é influenciada pelo tempo e temperatura de cristalização do gel da zeólita. O emprego de tempos relativamente curtos ou baixas temperaturas favorece a formação de um sólido amorfo, enquanto longos tempos ou elevadas temperaturas favorecem a formação de mesoporos intracristalinos na mordenita. Por outro lado, tempos e temperaturas intermediárias favoreceram a formação da mordenita com uma estrutura hierárquica de poros e mesoporos desordenados. O aumento da cristalinidade da mordenita acarreta uma diminuição na área e no volume de mesoporos, mas promove um acréscimo na área e no volume de microporos. A área externa também tende a diminuir devido ao aumento do tamanho do cristal da mordenita em função da cristalinidade. Os sólidos obtidos foram susceptíveis à desaluminação durante a etapa de calcinação. A extensão da desaluminação diminuiu com o aumento do tempo ou da temperatura de cristalização, devido à inserção dos átomos de alumínio na rede da zeólita em formação. Porém, em tempos de cristalização longos e temperaturas altas, pode ocorrer a redispersão dos átomos de alumínio. Todos os sólidos apresentaram elevada acidez que aumentou com a cristalinidade. Entretanto, nas amostras preparadas em tempos curtos e temperaturas baixas, a maioria dos sítios apresentou força ácida moderada, enquanto aquelas obtidas em tempos longos e temperaturas altas apresentaram maior quantidade de sítios ácidos fortes.
The diffusion restrictions of the reactants caused by the micropores limit the use of zeolites for processing heavy molecules. This demands for the development of materials that can combine the properties of zeolites and of mesoporous materials. A significant number of experimental procedures, pre or post synthesis, has been suggested for obtaining hierarchically structured zeolites. The most successful synthesis involve the use of mesoporosity generating agents (nanoparticles and organic agents) or nanotemplates (templating in nanospaces), which generate solids with intracristaline mesoporosity with a narrow pore size distribution. This results in solids containing mesoporous besides the intrinsic zeolite micropores. However, there is not any systematic study which allows to state the effect of crystallization time and temperature of the synthesis gel on the properties of the final solid. In order to overcome this difficulty, the effect of time and temperature of the synthesis gel on the properties of mordenite-based materials with hierarchical pore structure was studied in this work. In the samples preparation a mesoporosity generating organosilane (TPOAC, [3-(trimethoxysilyl) propyl] octadecyldimethylammonium chloride) was added to the synthesis gel of mordenite, which was crystallized for different times and temperatures. The solids were then submitted to ion exchange with ammonium chloride and further calcination to obtain the acidic form of the zeolite. The samples were characterized by thermogravimetry, Fourier transformed infrared spectroscopy, X-ray diffraction, textural analysis by nitrogen adsorption, 29Si and 27Al NMR, scanning electron microscopy and acidity measurements by ammonia desorption. It was observed that the formation of mordenite containing mesoporous is affected by the time and temperature of crystallization of the zeolite gel. The use of relatively short times and low temperatures favors the formation of an amorphous solid, while long times or high temperatures favor the formation of intracristaline mesoporosity in the mordenite. On the other hand, intermediate times and temperatures favor the formation of mordenite with hierarchical pore structure and disordered mesopores. The increase in mordenite crystallinity leads to a decrease in mesopore area and volume but promotes an increase in micropore area and volume. The external area also tends to decrease due to the increased crystal size as a function of mordenite crystallinity. The solids obtained were susceptible to dealumination during the calcination step. The degree of dealumination decreased with the increasing crystallization time or temperature due to the insertion of aluminum atoms in the zeolite lattice. However, at long crystallization times and high crystallization temperatures the redispersion of aluminum atoms can occur. All solids showed high acidity which increased as a function of crystallinity. However, the samples prepared at short times and low temperatures showed the majority of moderate acid sites of medium strength, whereas those obtained at long times and high temperatures have more strong acid sites. Thus, intermediate times and temperatures favor the formation of solids having zeolitic characteristics and high mesoporosity.

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Silva, Bruno José Barros da. "Obtenção de materiais com estrutura hierárquica de poros através da dessilicação da Zeólita Zsm-22." Universidade Federal de Alagoas, 2017. http://www.repositorio.ufal.br/handle/riufal/1710.

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The present work deals with the generation of mesoporosity in ZSM-22 zeolite (TON structure). In a first part the synthesis of ZSM-22 was studied through a methodology similar to that presented by Valyocsik (1990), followed by an addition of an amphiphilic trimethoxyphenylsilane organosilane (TMPHS) in the synthesis gel, and by another substitution of 20% of the silica required for the synthesis by silanized silica beads by TMPHS. In the second part, the formation of mesoporosity by post-synthesis treatment with NaOH solution was studied, varying the concentration of 0.2, 0.4 and 0.6 mol.L-1 at a temperature of 70 °C per 1hour. The zeolites obtained were characterized by X-ray diffractometry (XRD), nitrogen adsorption at -196 °C, scanning electron microscopy (SEM), thermogravimetric analysis (ATG), absorption spectroscopy in the infrared region with Fourier transform (FT-IR) and desorption of ammonia at the programmed temperature. The catalysts that presented the best textural properties were submitted to the catalytic test with the n-hexane cracking model reaction. The diffractograms of the synthesized samples showed that they presented the main peaks referring to the TON structure, and that the desilicated samples maintained in their entirety their crystalline structure. The thermogravimetric curves presented four mass loss events, reaching values close to 10% of total loss. Infrared identified absorption bands characteristic of zeolitic materials. The micrographs of the TON-P sample showed crystal agglomerates in cylindrical form 2 μm in length. The pore diameter distribution of the desilicated samples presented a distribution in the range of 2 to 100 nm, proving one of additional mesoporosity due to the desilication process, with a higher formation of mesopores for the samples submitted to the treatments with higher OH- concentration, which caused an increase in the total acidity by the reduction of the Si/Al ratio. The desilicated samples presented a lower conversion compared to the precursor, but with higher stability in the conversion rate, with selectivity to formation of propene and isobutane.
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
O presente trabalho abordou a geração de mesoporosidade na zeólita ZSM-22 (estrutura TON). Numa primeira parte estudou-se a síntese da ZSM-22 via metodologia similar à apresentada por Valyocsik (1990), seguida por uma adição de um organossilano anfifílico trimetoxifenilsilano (TMPHS) no gel de síntese, e por outra via substituição de 20% da sílica requerida para a síntese por esferas de sílica nanométricas silanizadas por TMPHS. Na segunda parte estudou-se a formação de mesoporosidade por tratamento pós-síntese com solução de NaOH, variando-se a concentração de 0,2, 0,4 e 0,6 mol.L-1 à temperatura de 70°C por 1 hora. As zeólitas obtidas foram caracterizadas por difratometria de raios X (DRX), adsorção de nitrogênio à -196°C, microscopia eletrônica de varredura (MEV), análises termogravimétricas (ATG), espectroscopia de absorção na região do infravermelho com transformada de Fourier (FT-IR) e dessorção de amônia à temperatura programada. Os catalisadores que apresentaram melhores propriedades texturais foram submetidos ao teste catalítico com a reação modelo de craqueamento do n-hexano. Os difratogramas das amostras sintetizadas mostraram que estas apresentaram os principais picos referente à estrutura TON, e que as amostras dessilicadas mantiveram na sua integralidade sua estrutura cristalina. As curvas termogravimétricas apresentaram quatro eventos de perda de massa, obtendo-se valores próximos a 10% de perda total. Os infravermelhos identificaram bandas de absorção características dos materiais zeolíticos. As micrografias da amostra TON-P mostraram aglomerados de cristais em forma cilíndrica com 2 µm de comprimento. A distribuição de diâmetro de poros das amostras dessilicadas apresentaram uma distribuição na faixa de 2 a 100 nm, comprovando-se uma de mesoporosidade adicional devido ao processo de dessilicação, havendo maior formação de mesoporos para as amostras submetidas aos tratamentos com maior concentração de OH-, o que provocou um aumento na acidez total pela diminuição da razão Si/Al. As amostras dessilicadas apresentaram uma menor conversão perante a precursora, mas tendo maior estabilidade na taxa de conversão, havendo uma seletividade para formação de propeno e isobutano.

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Oliveira, Fernando Jose Volpi Eusebio de. "Hibridos inorganico-organicos mesoporosos nanoestruturados = aspectos estruturais e energeticos das interações cations-centros basicos na interface solido/liquido." [s.n.], 2009. http://repositorio.unicamp.br/jspui/handle/REPOSIP/250026.

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Orientador: Claudio Airoldi
Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Quimica
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Resumo: Três conjuntos de sílicas mesoporosas foram sintetizados com os agentes direcionadores dodecilamina, brometo de cetiltrimetilamônio (CTAB) e co-polímero tribloco EO20-PO70-EO20 (P123 ¿ Pluronic®). As matrizes inorgânicas foram funcionalizadas com agentes sililantes contendo de um a três átomos de nitrogênio nas cadeias. Além disso, estes silanos reagiram com o ligante tiocarbamida, em uma etapa livre de solvente, anteriormente à formação da sílica, em processo de co-condensação. A rota de síntese empregada para as amostras preparadas a partir do direcionador P123 foi a pósfuncionalização. Para as estruturas obtidas utilizando-se dodecilamina, do tipo HMS, observou-se o colapso da estrutura após a extração do direcionador, conforme mostraram os espectros de IV e os difratogramas antes e depois do processo de remoção. Contudo, as amostras apresentaram tamanho médio de poros na faixa que constituem os materiais mesoporosos, sendo então investigados no estudo da remoção de metais tóxicos. Para as amostras preparadas CTAB e P123 foram observados os sinais da reflexão típica de materiais do grupo p6mm, denominada 2D-hexagonal, cujas amostras análogas aos materiais MCM-41 e SBA-15, respectivamente. Todos os híbridos modificados com tiocarbamida foram aplicados em sorção de íons metálicos, ajustados ao modelo não linear de sorção de Langmuir. As interações na interface sólido/líquido foram determinadas por microcalorimetria. Os resultados revelaram que os materiais do tipo SBA-15 apresentam alta capacidade de remoção de Cu, Cd e Pb, devido ao procedimento de pós-funcionalização. As amostras obtidas por co-condensação, do tipo HMS e MCM-41, apresentaram capacidade máxima de sorção superior aos resultados observados na literatura para materiais análogos. Os experimentos calorimétricos mostraram que as interações entre os sólidos e os íons metálicos são exotérmicas, com exceção dos íons Pb. Outro aspecto destacado trata-se da importância do termo entrópico, que parece reger o processo na maioria dos casos, devido à liberação de moléculas de água coordenadas aos íons e às matrizes. Portanto, todos os sistemas estudados apresentaram um comportamento energeticamente favorável.
Abstract: Three set of mesoporous silicas have been synthesized through dodecylamine, cetiltrimethylamonium bromide (CTAB) and the triblock co-polymer EO20-PO70-EO20 (P123 ¿ Pluronic®) as structure directing agents (sda). The inorganic matrices have been functionalized with silylating agents presenting from one to three nitrogen atoms on their chains. In addition, these silanes reacted with thiocarbamide through a free-solvent step, before the silica formation, by co-condensation process. However the synthetic route for the samples templated by P123 was the post-grafting. For the structures obtained by using dodecylamine, HMS-like, it was observed the structure collapsed after template removal, as shown by IR spectra and XRD patterns, before and after the removal process. These samples presented pore size comprised on mesoporous range, being then investigated for toxic metal removal capacity. For the samples prepared from CTAB and P123, the typical reflections for p6mm group materials, named 2D-hexagonal, were observed, and these samples are analogous to MCM-41 and SBA-15 materials, respectively. All thiocarbamide-modified hybrids were applied to metal ions sorption, being adjusted to Langmuir non-linear fit model. The interactions at the solid/liquid interface were determined through microcalorimetry. The results reveal that the SBA-15-like materials present high removal capacity for Cu, Cd e Pb, due to the post-grafting procedure. The samples obtained through cocondensation route, HMS- and MCM-41-like, presented maximum sorption capacity higher than those results for analogous published materials. With exception of Pb, all calorimetric determinations showed that the interactions between the solids and metal ions are exothermic. Another highlighted feature is about the importance of the entropic term that seems to rule the processes for several cases, due to the ion and surface coordinated water molecules displacement. Thus, all studied systems presented an energetically favorable behavior.
Doutorado
Quimica Inorganica
Doutor em Ciências

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Costa, Luelc Souza da 1984. "Materiais híbridos mesoestruturados funcionalizados via co-condensaçãoi aplicados na sorção." [s.n.], 2012. http://repositorio.unicamp.br/jspui/handle/REPOSIP/250045.

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Orientador: Claudio Airoldi
Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Química
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Resumo: A síntese de sílicas mesoporosas funcionalizadas pela a rota de co-condensação tem despertado a atenção de diversos grupos de pesquisas devido a sua praticidade. Esta síntese consiste na condensação simultânea entre as moléculas dos organossilanos e as moléculas da fonte de silício (TEOS) através do método sol-gel. Isso faz com que a incorporação de grupos orgânicos na estrutura da sílica ocorra de forma direta. No entanto, em muitos casos, os híbridos preparados dessa forma podem apresenta uma má formação estrutural devido a presença dos grupos orgânicos. Nesse trabalho foram sintetizados materiais híbridos com o agente direcionador copolímero tribloco EO20-PO70-EO20 (P123 ¿ Pluronic®). Foram escolhidos grupos organossilanos contendo em suas estruturas sítios básicos Lewis tais como grupos carbonílicos, enxofre e nitrogenados. Os espectros na região do infravermelho juntamente com a análise elementar e ressonância magnética nuclear mostraram concordância que o ancoramento dos grupos orgânicos na matriz inorgânica dos híbridos ocorreu de forma satisfatória. As isotermas de sorção e dessorção de nitrogênio mostraram que todas as isotermas são do tipo IV com histerese do tipo H1 que são característicos de matérias mesoporosos e que os poros dos materiais estão na faixa de mesoporosidade, a área superficial é dependente do tamanho da molécula utilizada na funcionalização. Foram observados os sinais da reflexão típica de materiais do grupo p6mm, denominada 2D-hexagonal, análogas ao material SBA-15. Portanto, todos os híbridos foram sintetizados de forma ordenada como proposto. Os materiais híbridos foram aplicados em sorção de íons metálicos, e na sorção de corantes. Os dados experimentais foram ajustados aos modelos de isoterma de sorção de Langmuir, Freudlich e Sips usando os métodos de regressão não linear. As sílicas apresentaram boa capacidade de sorção tanto para os metais quanto para o corante. Fato esse devido aos sítios básicos de Lewis, de nitrogênio e enxofre presentes e a possibilidade desses grupos serem protonados em solução e estes sítios interagirem com os grupos sulfonados do corante.
Abstract: The synthesis of functionalized mesoporous silicas by a co-condensation route has attracted attention of many research groups due to its practicality. The synthesis consists of the simultaneous condensation among organosilane molecules and the molecules of silicon source by sol-gel method. This makes the incorporation of organic groups in the silica structure occurs directly. However, in many cases, the hybrids may this way prepared has a structural deformation due to the presence of the organic groups. In this work were synthesized hybrid materials with directing agent triblock copolymer EO20-PO70-EO20 (P123 - Pluronic ®).Were chosen organosilanes containing groups in their structures Lewis basic sites such as carbonyl groups, nitrogen and sulfur. Infrared spectra combined with elemental analysis and nuclear magnetic resonance proved that the organic chains were satisfactorily anchored to the inorganic matrices. The nitrogen adsorption-desorption analyses generated isotherms of type IV and hysteresis H1 that are typical of mesoporous materials, where asthe pore size distribution showed that the pores of the silicas are in the mesoporous range. The BET method was applied to acquire the surface areas of the solids, which were found to be dependent on the size of the molecule used for the functionalization processes. SAXS patterns of all samples demonstrated well-resolved peaks characteristic of the typical p6mm space group, called 2D-hexagonal, similar to SBA-15.The hybrid materials were applied to the sorption of metallic ion sand dyes, showing good sorption capacities for both kinds of contaminants. The nitrogen and sulfur Lewis basic sites anchored to the silica inorganic back bone can be protonated to interact with the sulfonated groups of the dyes. The experimental data were fitted to the Langmuir, Freundlich and Sips sorption isotherms using the non-linear regression.
Mestrado
Quimica Inorganica
Mestre em Química

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Lopes, Glenda Cristina da Silva. "Produ??o de mordenita mesoporosa por s?ntese direta usando diferentes direcionadores." Universidade Federal Rural do Rio de Janeiro, 2016. https://tede.ufrrj.br/jspui/handle/jspui/1759.

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Funda??o de Apoio a Pesquisa Cient?fica e Tecnol?gica da UFRRJ-FAPUR
In the present dissertation it was conduced the study of the mesoporous mordenite production by the direct synthesis using hydrothermal media or dry gel convertion. Activated charcoal, starch, carboxymethylcellulose and carbon black were used as mesoporosity templating. To evaluate the effect of these templates, samples were prepared with molar composition of 20 SiO2: 1 Al2O3: 6 Na2O: 600 H2O, by hydrothermal synthesis and 20 SiO2: 1 Al2O3: 4 Na2O, by dry synthesis, following procedures described in the literature and adding different amounts of templates to the synthesis gel. As reagents for the synthesis gel assay, were utilized sodium hydroxide, sodium aluminate, silica (Aerosil 200) and deionized water. The synthesis temperature was 175 ? C, while the synthesis time was 5 days and 3 days for the hydrothermal and dry method, respectively. For characterization of the samples was used X-ray diffraction (XRD), analysis by nitrogen adsorption/desorption measurements and determination of the acidity by temperature programmed desorption of ammonia (NH3-TPD). An evaluation of the samples was carried out using the n-heptane cracking reaction at 380 ? C. By X-ray diffraction, it was observed that the majority of the experiments formated of mordenite phase. The textural properties, particularly the volume of mesopores, improved in most samples synthesized in the presence of the template, however, the values obtained were lower than those defined in the literature for mesoporous materials. The samples showed only a peak of ammonia adsorption in NH3-TPD profiles, related to weak acid sites. Most samples synthesized in the presence of drivers showed an increase in the conversion of n-heptane, while the samples obtained by dry gel convertion showed higher conversion than the hydrothermally synthesized.
No presente trabalho foi realizado o estudo da produ??o de mordenita mesoporosa a partir da s?ntese direta, em meio hidrot?rmico e seco, na presen?a do carv?o ativado, amido, carboximetilcelulose e negro de fumo como direcionadores de mesoporosidade. Para avaliar o efeito desses direcionadores, foram preparadas amostras com composi??o molar de 20 SiO2: 1 Al2O3: 6 Na2O: 600 H2O, pela s?ntese hidrot?rmica e 20 SiO2: 1 Al2O3: 4 Na2O, pela s?ntese seca, seguindo os procedimentos descritos na literatura e adicionando quantidades diferentes dos direcionadores ao gel de s?ntese. Como reagentes para o gel de s?ntese, foram utilizados hidr?xido de s?dio, aluminato de s?dio, s?lica (aerosil 200) e ?gua deionizada. A temperatura de s?ntese foi de 175 ?C, enquanto o tempo de s?ntese foi de 5 dias e 3 dias, para o m?todo hidrot?rmico e seco, respectivamente. Para caracteriza??o das amostras usou-se difra??o de raios X (DRX), an?lise textural por medidas de adsor??o/dessor??o de nitrog?nio e determina??o da acidez por dessor??o de am?nia ? temperatura programada (TPD-NH3). Realizou-se a avalia??o catal?tica das amostras atrav?s da rea??o de craqueamento de n-heptano a 380 ?C. Pelos difratogramas de raios X, foi observado que na maioria dos experimentos ocorreu a forma??o da mordenita. As propriedades texturais, especialmente o volume de mesoporos, melhoraram na maioria das amostras sintetizadas na presen?a do direcionador, por?m, os valores obtidos foram inferiores aos definidos pela literatura para materiais mesoporosos. As amostras apresentaram apenas um pico de adsor??o de am?nia nos perfis de TPD-NH3, referentes aos s?tios ?cidos fracos. A maioria das amostras sintetizadas na presen?a dos direcionadores apresentou aumento na convers?o do n-heptano, sendo que as amostras obtidas por s?ntese em meio seco apresentaram maior convers?o do que as sintetizadas em meio hidrot?rmico.

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Oliveira, Vaeudo Valdimiro 1982. "Sílicas mesoporosas e silicatos lamelares contendo agentes organofuncionalizados : sorção e liberação controlada de fármacos." [s.n.], 2012. http://repositorio.unicamp.br/jspui/handle/REPOSIP/250068.

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Orientador: Claudio Airoldi
Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Química
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Resumo: Na presente investigação foram sintetizados os híbridos inorgânico-orgânicos micro/mesoestruturados: a) silicato lamelar do tipo kanemita sódica, b) sua forma quimicamente modificada com cobre e c) sílica mesoporosa SBA-16. A combinação dos reagentes Na2SiO3/NaOH/etanol e Na2SiO3/NaOH/Cu(NO3)2/etanol propiciaram a obtenção de kanemita sódica e sua forma contendo o cobre incorporado na estrutura inorgânica, através da substituição isomórfica do silício nas razões molares Si/Cu = 50, 100 e 200. Para as sílicas mesoporosas foram usados sistemas formados por copolímeros F127/TEOS/H2O, F127/TEOS/etanol/H2O e F127/TEOS/butanol/H2O em meio ácido. Os materiais organofuncionalizados previamente intercalado com dimetilsulfóxido (DMSO) e etilenodiamina (EN) formam os sólidos lamelares Na-KN-DMSO, Na-KN-EN e Cu-KN-EN, através do processo de pós-síntese com o agente sililante 3-iodopropiltrimetoxissilano, que reagiu subsequentemente com dietil iminodiacetato e benzidina, formando os híbridos mesoporosos. Os híbridos lamelares foram aplicados na sorção de metais e corantes em soluções aquosas. Dentre os cátions bário, cobalto e cobre, o cobre foi mais facilmente sorvido em Na-KN-EN quando comparado com Na-KN-DMSO. No caso dos corantes verde brilhante e azul reativo 15, o primeiro foi também mais eficiente na sorção. No processo de liberação de fármacos amoxicilina e omeprazol foram utilizados os híbridos mesoporosos. Os dados de liberação mostram que o primeiro fármaco apresentou uma cinética de liberação satisfatória no fluido intestinal simulado (FIS), enquanto que o omeprazol liberou em maior quantidade no fluido gástrico simulado (FGS)
Abstract: The present investigation deals with the syntheses of inorganic-organic nano/mesostrutered hybrids: a) sodic lamellar silicate kanemite, b) its chemically modified form with copper and c) SBA-16 mesoporous silicas. The reagents combination Na2SiO3/NaOH/ethanol and Na2SiO3/NaOH/Cu(NO3)2/ethanol enabled to obtain sodic kanemite and its synthesized form containing incorporated copper in the inorganic structure, through the isomorphic substitution of silicon using the molar ratio Si/Cu = 50, 100 and 200. For mesoporous silicas the copolymers F127/TEOS/H2O, F127/TEOS/ethanol/H2O and F127/TEOS/butanol/H2O in acidic condition were used. The synthesized organofunctionalized materials were previously intercalated with dimethylsulfoxide (DMSO) and ethylenediamine (EN) in the Na-KN-DMSO, Na-KN-EN and Cu-KN-EM lamellar solids, through the post-synthesis process with the silylating agent 3-iodopropyltrimethoxysilane, which subsequently reacted with diethyl iminodiacetate and benzidine. The lamellar hybrids were applied for cation and dye sorption processes. Among barium, cobalt and copper, the last cation was more favorable sorbed in Na-KN-EN, when compared with Na-KN-DMSO. In case of brilliant green and reactive blue 15 dyes, the first one was also more efficient in sorption. The controlled drug delivery process, amoxicillin and omeprazole were applied with mesoporous hybrid systems. The delivery data demonstrated that the first drug presented a satisfactory kinetic in the simulated intestinal fluid (SIF), while omeprazole presented high amount in the simulated gastric fluid (SGF)
Doutorado
Quimica Inorganica
Doutor em Ciências

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Strauss, Mathias 1982. "Efeito da nanoestruturação de óxidos semicondutores suportados em matrizes mesoporosas sobre a atividade fotocatalítica." [s.n.], 2012. http://repositorio.unicamp.br/jspui/handle/REPOSIP/250546.

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Orientador: Ítalo Odone Mazali
Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Química
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Resumo: Materiais baseados no óxido de titânio (TiO2) são bastante explorados no desenvolvimento de tecnologias ambientalmente amigáveis que utilizam a radiação solar para a remediação de poluentes atmosféricos e na água, bem como na geração de energia. Aspectos relacionados aos efeitos da nanoestruturação sobre a atividade fotocatalítica do TiO2 são amplamente discutidos na literatura. Dentro deste contexto, a presente tese teve como objetivos centrais estudar os efeitos da cristalinidade, tamanho de cristalito e dopagem com metais de transição de nanopartículas de TiO2 suportadas em sílicas mesoporosas sobre atividade fotocatalítica. Foram utilizados dois protocolos distintos de síntese: método sol-gel (para estudo do efeito da cristalinidade) e método de ciclos de impregnação-decomposição (para estudo do efeito do tamanho de cristalito e dopagem com metais de transição). As propriedades estruturais, ópticas e eletrônicas das nanopartículas de TiO2 foram caracterizadas principalmente por difratometria de raios X e espectroscopias Raman (aplicada ao Modelo de Confinamento de Fônons) e UV-vis (aplicada ao Modelo de Aproximação da Massa Efetiva). A atividade fotocatalítica dos materiais foi avaliada quanto à fotodescoloração de azul de metileno, fotodegradação de ácido salicílico, fotogeração de radicais hidroxila e/ou fotooxidação de iodeto. Os materiais sintetizados a partir da rota sol-gel seguida por tratamento térmico em diferentes temperaturas permitiram o entendimento dos efeitos da cristalinidade de nanopartículas de TiO2 de tamanho fixo sobre a atividade fotocatalítica. Nanopartículas de baixa cristalinidade apresentaram menor ordem e maior quantidade de defeitos estruturais que atuaram como sítios de aprisionamento e recombinação dos portadores de carga diminuindo a atividade fotocatalítica. Quanto a influência do tamanho de cristalito, o aumento no tamanho diminuiu o valor em energia da banda proibida e aumentou a faixa de absorção do espectro UV-vis dos materiais, o que aumentou a capacidade de fotogeração de radicais OH. Por outro lado, o aumento do tamanho das nanopartículas leva também a uma redução na razão aréa superficial/volume das nanopartículas de TiO2 que trouxe redução na atividade catalítica, frente as reações de fotodescoloração de azul de metileno e fotodegradação de ácido salicílico, deixando clara a dependência com os mecanismos de adsorção e dessorção dos reagentes e produtos na superfície do fotocatalisador. A dopagem das nanopartículas de TiO2 com diferentes metais de transição (Mn, Co, Zn, Ce, Cu, Mo, Ni e Sn) promoveu a redução no valor da banda proibida e aumento na absorção de luz na região do visível. A fotooxidação de I- pelas nanopartículas de TiO2 dopadas mostrou-se fortemente dependente da formação de defeitos pontuais e distorções estruturais que são responsáveis pelo aprisionamento e recombinação dos elétrons e buracos
Abstract: Titanium oxide (TiO2) based material are much explored in the development of environmental friendly technologies that use the solar radiation to mitigate atmospheric and water pollutants, and on energy generation. Aspects related to the nanostructure of the TiO2 over its photocatalytic activity had been widely discussed in the literature. In this context, this thesis has as main objective studing the effects of the cristallinity, cristallite size and transition metals doping of TiO2 nanoparticles supported in mesoporous silicas over the photocatalytic activity. Two distinct synthesis protocols were used: sol-gel method (to study the cristallinity effects) and the impregnation and decomposition cycles method (to study the cristallite size and transition metal doping effects). The structural, optical and electronic properties of the TiO2 nanoparticles were studied using mainly X ray diffractometry, and Raman (applied to the Phonons Confinament Model) and UV-vis (applied to the Effective Mass Approximation Model) spectroscopies. The photocatalytic activity of the materials were tested against the photodecolorization of methylene blue, photodegradation of salycilic acid, photogeneration of OH radicals and/or photooxidation of I-. The material synthesized using the sol-gel route followed by thermal treatment permitted the understanding of the cristallinity effects of size-fixed TiO2 nanoparticles over the photocatalytic activity. Nanoparticles with low cristallinity presented lower structural order and higher number of structural defects that acted as trapping and recombination sites lowering the photocatalytic activity. Regarding the influence of the crystallite size, the increase in size decreased the band gap energy value and enhanced the UV-vis absorption range of the materials, that resulted in an enhanced OH radicals photogeneration capacity. By the other side, the increase in the particle size lead also to a reduction of the surface area/volume ratio of the TiO2 nanoparticles that brought reduction in the catalytic activity at the photodecolorization of methylene blue and photodegradation of salycilic acid reactions, letting clear its dependency with the adsorption and dessorption mechanisms of the reagents and products on the photocatalyst surface. Doping the TiO2 nanoparticles with different transition metals (Mn, Co, Zn, Ce, Cu, Mo, Ni e Sn) resulted in band gap lowering and enhancement of the visible radiation absorption. The photooxidation of I- had shown strong dependence with the generation of punctual defects and structural distortions that are responsible for the electrons and holes trapping and recombination
Doutorado
Quimica Inorganica
Doutor em Ciências

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Tan, Yu-May. "Mesoporous materials." Thesis, University of Southampton, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.370067.

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Bacani, Rebeca. "Sistemas porosos de zircônia e céria." Universidade de São Paulo, 2009. http://www.teses.usp.br/teses/disponiveis/43/43134/tde-12042010-194950/.

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Neste trabalho foram desenvolvidas sínteses de ZrO2-x%CeO2, baseadas na preparação da sílica mesoporosa ordenada SBA-15, utilizando um molde de co-polímero tribloco Pluronic P-123, diversos precursores de zircônio e cério e diferentes métodos. Os métodos de síntese testados foram com: precursores a base de cloreto hidratado (com x=50, 70 e 90), precursores a base de cloreto anidro (x=50 e 90), precursores a base de nitrato (x=90), solução supersaturada de nitrato (x=90), do tipo híbrido com Zr, Ce e Si (com 10%mol de Si e x=90), paliçada de Si (com 10 e 30%mol de Si e x=90) e paliçada de Si com temperatura de síntese de 40°C (com 30%mol de Si e x=90). Visando obter paredes compostas por fase cristalina única e grande área supercial, para futuras aplicações em catálise. Os compósitos polímero/(zircônio-cério) sintetizados a partir de cloretos formam uma estrutura lamelar organizada, que se transforma num sistema poroso desordenado após a calcinação para a retirada do molde. O processo de decomposição/remoção do molde até 540°C produz mudanças de fase nos precursores a base dos metais utilizados, além das transformações morfológicas. Para uma concentração de 90% de CeO2 obtém-se um material poroso com paredes homogêneas de estrutura fcc e de maior estabilidade mecânica. Os valores de área supercial e volume de poros dependem fundamentalmente do método de preparação do material e independem da concentração de CeO2. Aumentos signicativos da área supercial (~100m²/g) e do volume de poros (~0,4cm³/g) são obtidos a partir da introdução de sílica nesses sistemas. Foram alcançados área supercial aproximadamente 6 vezes maior e tamanho de cristalito ~4 vezes superior à do material similar nanocristalino preparado por gel-combustão. Esses valores também são iguais aos reportados para os melhores materiais porosos a base de zircônia-céria, preparados por outros métodos, encontrados na literatura.
In this work synthesis of ZrO2-x%CeO2 were developed, based on the formation of ordered mesoporous silica SBA-15, using the triblock co-polymer Pluronic P-123 as template, different precursors of zirconium and cerium and dierent methods. The tested synthesis methods were with: hydrated chloride precursors (with x=50, 70 and 90), anhydrous chloride precursors (x=50 and 90), nitrate precursors (x=90), supersaturated nitrate solution (x=90), hybrid type with Zr, Ce and Si (with 10%mol of Si and x=90), Si palisade (with 10 and 30%mol of Si, and x=90) and Si palisade with synthesis temperature of 40°C (with 30%mol of Si and x=90). Aiming to obtain crystalline single phase walls and large supercial area, for future applications in catalysis. The composites polymer/zirconium-cerium synthesized from chloride precursors formed an organized lamellar structure, which transforms into a disordered porous system after the calcination to remove the template. The template decomposition/removal up to 540°C produces phase transformations in the metallic precursors, besides morphological changes. A CeO2 content of 90% resulted in a porous material with homogeneous walls of fcc structure and better mechanical stability. The values of supercial area and pore volume depend mostly on the preparation method rather than the CeO2 concentration. Signicant increases on supercial area (~100m²/g) and pore volume (~0.4cm³/g) were obtained with the introduction of silica into the material. Supercial area ~6 times larger and crystallite size ~4 times superior to a nanocrystalline similar material, made by gel-combustion were attained. These figures are also equal to the ones reported for the best porous zirconia-ceria materials, prepared by other routes, found in the literature.

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ROCHA, Clarice Oliveira da. "Utilização do sapo-5 micro e mesoporoso impregnados com níquel e/ou zinco para acompanhamento da dessulfurização da mistura heptano-tiofeno." Universidade Federal de Campina Grande, 2014. http://dspace.sti.ufcg.edu.br:8080/jspui/handle/riufcg/236.

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CNPq
Propostas têm aparecido visando à remoção do enxofre nos combustíveis por intermédio dos processos de adsorção. Com isso, a utilização desse método para a dessulfurização vem se expondo como um bom potencial de aplicação, tanto do ponto de vista econômico como ambiental. As peneiras moleculares, do tipo silicoaluminofosfato (SAPO), vêm se apresentando como um excelente adsorvente, com uma ótima estabilidade térmica e hidrotérmica e com a impregnação de metais, tornando-se seletiva a adsorção. Assim, sintetizou-se SAPO-5 (microporoso) e SAPO-5M (mesoporoso), impregnados com diferentes teores dos metais de transição, níquel e/ou zinco. Esses adsorventes foram utilizados para a remoção do enxofre presente na mistura modelo (Heptano / Tiofeno). Para isso, foram realizadas técnicas de caracterização como TG, DRX, EDX e BET, bem como um acompanhamento cinético a fim de avaliar a eficiência da adsorção e as isotermas de equilíbrio. Foi confirmado a mesoporosidade do SAPO-5M, uma vez que o mesmo apresentou as isotermas características tipo IV (típica de material mesoporoso). O volume e o diâmetro dos poros do SAPO-5 microporoso e mesoporosos não foram totalmente obstruídos após a impregnação. Para os adsorventes mesoporosos houve um aumento de quatro vezes no diâmetro do poro, em relação ao micro. Embora, tenha apresentado redução na intensidade de difração de raios X após a impregnação, dos óxidos de níquel e/ou de zinco, obteve-se um material cristalograficamente ordenado. Ocorreu total remoção do direcionador, mostrando que a calcinação foi eficiente e o material é estável a altas temperaturas. Ademais, conseguiu-se atenuar a quantidade de enxofre de 500 ppm para cerca de 96,3 ppm, uma redução de 80%, para o adsorvente mesoporoso 0,25%Ni 0,75%Zn/SAPO-5M, cuja capacidade de adsorção de enxofre foi de 40 mg S/gadsorvente. O adsorvente com 1%Zn/SAPO-5, apresentou maior capacidade de adsorção (30 mg S/gadsorvente), dentre os materiais microporosos, conseguindo reduzir o teor de enxofre de 500 ppm para 163 ppm. Para os demais suportes e adsorventes ocorreu uma redução de aproximadamente 31 % do teor de enxofre na mistura modelo. Conclui-se que a síntese do mesoporoso foi eficiente e que o material utilizado se mostrou eficaz na remoção desse contaminante na mistura modelo.
Proposals have appeared aiming at the sulfur removal in fuels by means of adsorption processes. Thus, the use of this method for the desulfurization exposing themselves like a good application potential, both economically and environmentally. The molecular sieves silicoaluminiumfosfate type (SAPO), has been presented as an excellent adsorbent with optimum thermal and hydrothermal stability and metals impregnation, making it selective adsorption. Thus was synthesized SAPO-5 (microporous) and SAPO-5M (mesoporous) impregnated with different amounts of transition metals, nickel and/or zinc. These adsorbents were used for removal of sulfur present in the mixture model (Thiophene / Heptane). For this, characterization techniques as TG, XRD, EDX and BET were performed, as well as a kinetic monitoring to assess the efficiency of adsorption and equilibrium isotherms. It was confirmed mesoporosity of SAPO-5M, since the isotherms showed the same type IV characteristics (typical of mesoporous materials). The volume and pore diameter of the microporous and mesoporous SAPO-5 were not totally blocked after impregnation. For mesoporous adsorbents an increase of four times the pore diameter in relation to the microporous. Although, has shown a reduction in the intensity of X-ray diffraction after the impregnation of the oxides of nickel and/or zinc, gave a crystallographically ordered materials. Complete removal of the template occurred, showing that the calcination was efficient and the material is stable at high temperatures. Furthermore, we were able to attenuate the amount of sulfur 500 ppm to about 96.3 ppm, a reduction of 80% for the mesoporous adsorbent Ni 0.25% 0.75% Zn/SAPO-5M, whose adsorption capacity sulfur was 40 mg S/g of adsorbent. The adsorbent of 1% Zn/SAPO-5 showed higher adsorption capacity (30 mg S/g of adsorbent) among microporous materials, achieving reduced sulfur content from 500 ppm to 163 ppm. For other supports and adsorbent was reduced by approximately 31% of the sulfur content in the mixture model. It is concluded that the synthesis of mesoporous was effective and that the material used is effective in the removal of this contaminant in the mixture model.

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15

Lebold, Timo. "Mesoporous silica nanostructures." Diss., lmu, 2010. http://nbn-resolving.de/urn:nbn:de:bvb:19-118194.

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16

Warnant, Jérôme. "Synthèse et caractérisation de nanomatériaux fonctionnels siliciques structurés à l'aide de micelles complexes de copolymères séquencés doublement hydrophiles." Thesis, Montpellier, Ecole nationale supérieure de chimie, 2010. http://www.theses.fr/2010ENCM0005/document.

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Ce travail s'est intéressé à la conception et à l'élaboration de nouveaux agents structurants de silice constitués d'assemblages induits et réversibles de copolymères originaux : les copolymères séquencés doublement hydrophiles (DHBC). Un des systèmes étudiés est constitué d'un DHBC neutre-anionique PAPEO-b-PAA ou poly(acrylate methoxy poly(oxyde d'éthylène))-b-poly(acide acrylique). La séquence PAA est un polyacide faible dont le degré d'ionisation dépend du pH. En solution aqueuse et pour un pH bien choisi, l'association de ce copolymère à une polybase faible, de charge opposée à celle du PAA, (typiquement un oligochitosane) conduit à la formation de micelles complexes de polyions (PIC) sphériques de type cur/couronne. Ces micelles peuvent dans un premier temps conduire à la formation de matériaux mésostructurés hybrides hautement organisés. Dans un second temps, en jouant notamment sur les conditions de pH et de force ionique, il est possible de « contrôler » le taux d'extraction des espèces organiques pour obtenir des matériaux poreux fonctionnels capables de piéger des espèces de charge opposée à la fonctionnalité. Si des matériaux hybrides organisés sont obtenus, c'est parce que les équilibres des interactions mises en jeu entre les espèces organiques et inorganiques y sont favorables. Si une interaction polyamine/silice s'exerce aux dépens de l'interaction polyamine/DHBC, elle peut limiter le processus de mésostructuration par les micelles. Lorsqu'un DHBC neutre-cationique PEO-b-PDMAEMA ou poly(oxyde d'éthylène)-b-poly(méthacrylate de 2-(diméthylamine)éthyle) est utilisé en présence d'un polymère anionique tel que le PVS ou poly(acide sulfonique de vinyle), il joue un double rôle dans la synthèse des matériaux siliciques : une partie gère la croissance des particules de silice en interagissant avec les silicates et l'autre partie qui est complexée par des PVS joue le rôle d'agent structurant en apportant une mésostructuration au matériau. Enfin, une approche très prometteuse a permis d'encapsuler des principes actifs hydrosolubles chargés dans un matériau en les utilisant comme agent complexant du DHBC
This study focused on the design and development of new structuring agents of silica constituted of induced and reversible assemblies of original copolymers, the double hydrophilic block copolymers (DHBC). The first system studied consists of a neutral-anionic DHBC PAPEO-b-PAA ou poly(acrylate methoxy poly (ethylene oxide))-b-poly (acrylic acid). The PAA block is a weak polyacid with a degree of ionization depending on the pH. In aqueous solution and in a right pH range, the association of this copolymer with a weak polybase, an oppositely charged polyamine, such as an oligochitosan, leads to the formation of polyion complex micelles (PIC) with a core/corona structure. These micelles can direct the structure of highly organized inorganic materials with different types of mesostructures. In a second step, by adjusting the conditions of pH, ionic strength, it is possible to "control" the extraction of organic species to get functional porous materials able to trap species of charge opposite to the functionality. Organized materials are obtained because of a favourable balance of the interactions between organic and inorganic species. If a polyamine/silica interaction occurs at the expense of the interaction polyamine/DHBC, the mesostructuring process by the micelles is limited. A neutral-cationic DHBC PEO-b-PDMAEMA poly(ethylene oxide)-b-poly(2-(dimethylamine)ethyl) associated with an anionic PVS poly(vinyl sulfonic acid) polymer can play a dual role in the synthesis of silica materials: firstly managing the growth of silica particles by interacting with the silicates and secondly acting as a structuring agent in association with PVS, confering a mesostructuration to the material. Finally, a very promising approach allowed to encapsulate water-soluble and charged drugs in a material by using as silica complexing agent a complex between the drug and a DHBC

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17

Paula, Amauri Jardim de 1984. "Produção de veículos moleculares à base de nanoestruturas de sílica porosa para carreamento de compostos hidrofóbicos." [s.n.], 2012. http://repositorio.unicamp.br/jspui/handle/REPOSIP/249035.

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Orientador: Oswaldo Luiz Alves
Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Química
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Resumo: Partindo-se do método de Stöber, um elegante e eficiente processo de síntese de partículas coloidais de SiO2, adaptações foram feitas para que fosse possível produzir nanopartículas porosas (50-80 nm) com alto valor de área de superfície (~1000 m g), volume de poros (~1,5 m g) e alta estabilidade coloidal. As nanoestruturas são compostas de nanopartículas coloidais de sílica hierarquicamente funcionalizadas, com poros internos com estrutura desordenada e diâmetros que vão de 1,8 a 10 nanômetros, funcionalizados com grupos fenil, e superfície externa recoberta com grupos propilmetilfosfonato ionizáveis. A funcionalização hierárquica e quimicamente antagônica (hidrofóbica = poros internos; hidrofílica = superfície externa) permite que moléculas hidrofóbicas (baixa solubilidade em água) sejam facilmente incorporadas nas cavidades porosas hidrofóbicas, ao passo que as partículas se mantêm de forma estável dispersas em água por meses. Moléculas hidrofóbicas foram incorporadas pelas nanopartículas porosas de SiO2 em concentração de até 3% (m/m) através da mistura de suspensões coloidais aquosas desses nanomateriais e as moléculas insolúveis (pós). A capacidade de incorporação da molécula hidrofóbica em questão (camptotecina) foi significantemente maior que outros sistemas porosos de SiO2 que estão sendo atualmente usados. A eficiência dos veículos moleculares foi comprovada através do carreamento da camptotecina, um potente agente antitumoral que levou à inibição do crescimento de células leucêmicas humanas. Além disso, as abordagens sintéticas usadas nessa Tese também possibilitaram a funcionalização da superfície externa das nanopartículas com outros grupos orgânicos hidrofílicos e reativos, como o propilamina. Consequentemente, as características dessas nanopartículas de SiO2 aqui mostradas preenchem uma série de demandas científicas atuais: a necessidade de nanoestruturas porosas de sílica com ampla distribuição de tamanho de poro, com morfologia homogênea, estreita distribuição de tamanhos e com real dispersibilidade em água (coloidais). Assim, o conjunto de propriedades apresentado abre perspectivas envolvendo o uso desse sistema como uma plataforma tecnológica suscetível a várias aplicações, servindo como um veículo para dispersão e liberação de moléculas hidrofóbicas em meio aquoso
Abstract: Based on the Stöber method, an elegant and efficient process for synthesizing SiO2 colloidal nanoparticles, modifications were done in order to produce porous nanoparticles (50-80 nm) with high surface area (~1000 mg), volume of pores (~1,5 m g) and high colloidal stability. The nanostructures are made of hierarchically functionalized colloidal silica nanoparticles, with internal pores with disordered structure and diameters ranging from 1.8 to 10 nanometers, functionalized with phenyl groups; and external surface covered with ionizable propylmethylphosphonate groups. The hierarchical and chemically antagonistic functionalization (hydrophobic = internal pores; hydrophilic = external surface) allows hydrophobic molecules (low solubility in water) to be easily incorporated in the hydrophobic porous cavities, whereas particles maintain stably dispersed in water for months. Hydrophobic molecules were incorporated by the porous SiO2 nanoparticles in concentrations up to 3% (w/w) simply by mixing colloidal aqueous suspensions of these nanomaterials and insoluble molecules (powders). The uptake capacity for a specific hydrophobic molecule (camptothecin) was significantly higher than in other porous systems of SiO2 that have been currently used. The efficiency of the molecular vehicles was evidenced through the transportation of camptothecin, a potent antitumoral agent which led to the growth inhibition of human leukemic cells. Besides, the synthetic approach used in this thesis also made possible the functionalization of the external surface of nanoparticles with other hydrophilic and reactive organic groups, such as propylamine. Consequently, the characteristics of these SiO2 nanoparticles here shown fulfill several current scientific demands: necessity of porous silica nanostructures with a wide distribution of pore sizes, homogeneous morphology, narrow size distribution and real dispersibility in water (colloidal). Thereby, this set of properties opens up perspectives involving the use of this system as a technological platform susceptible to several applications, acting as a vehicle for the dispersion and liberation of hydrophobic molecules in aqueous media
Doutorado
Quimica Inorganica
Doutor em Ciências

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La, Salvia Nathália 1985. "Síntese e caracterização de MCM-41 impregnada com magnésio e cromo e suas propriedades catalíticas para reações de conversão de etanol." [s.n.], 2014. http://repositorio.unicamp.br/jspui/handle/REPOSIP/266085.

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Orientador: Gustavo Paim Valença
Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química
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Resumo: Peneiras moleculares do tipo MCM-41 foram sintetizadas com e sem alumínio estrutural e impregnadas com 5% de magnésio e 5 e 10% de cromo. As amostras foram então calcinadas e caracterizadas, e utilizadas na conversão catalítica de etanol. Esses materiais foram caracterizados por Espectroscopia de Infravermelho com Transformada de Fourier (FTIR), Difração de Raios X (DRX), Adsorção de Nitrogênio, Microscopia Eletrônica de Transmissão (TEM), Ressonância Magnética Nuclear (NMR), Espectrometria de Emissão Óptica por Plasma Acoplado Indutivamente (ICP-OES), Espectroscopia de Absorção Atômica (AAS), Análise Termogravimétrica (TGA), Dessorção a Temperatura Programada de NH3 (TPD-NH3), Quimissorção de CO2 e Picnometria de Hélio. Testes preliminares foram realizados para avaliar a eficiência do sistema reacional. Os testes catalíticos foram realizados em um reator de leito fixo, as temperaturas de reação utilizadas foram 600, 625, 650, 675, 700 e 725 K e as pressões de etanol de 4310, 3128 e 2240 Pa, as massas utilizadas foram 30 e 60mg, e o fluxo de etanol foi mantido constante em 2×10-6 m3 s-1. Os compostos identificados foram o etileno, acetaldeído, dietil-éter, 1.3-butadieno, etano, acetato de etila e, com seletividade abaixo de 2%, crotonaldeído, butiraldeído, butanol, acetona, propanol, propeno, metano e metanol. Foi realizado também o balanço de massa do sistema e foram determinados os valores dos graus de avanço de cada reação. Os cálculos dos efeitos difusivos demonstraram que a transferência de massa externa para reações a 675, 700 e 725 K podem ser limitantes da reação. Foram realizados testes de desativação de 48 horas. Foram realizados também os cálculos da taxa global de reação e da taxa de giro para todos os sólidos e em todas as condições de reação
Abstract: Molecular sieves of the MCM-41 type were synthesized and impregnated with 5% w/w Mg and loads of Cr: 5% and 10%. The solids were then calcined, characterized and tested as catalysts for the conversion of ethanol. These materials were characterized by Fourier Transform Infrared Spectroscopy (FTIR), X-Ray Diffraction (DRX), N2 adsorption, Transmission Electron Microscopy (TEM), Nuclear Magnetic Resonance (NMR), Inductively Coupled Plasma Optical Emission Spectrometry (ICP- OES), Atomic Absorption Spectroscopy (AAS), Thermogravimetric Analysis (TGA), Temperature-Programmed Desorption of NH3 (TPD-NH3), CO2 Chemisorption and Helium Pycnometry . Preliminary tests were conducted to evaluate the efficiency of the reaction system. The catalytic test reaction of ethanol was carried out in a fixed bed microreactor under differential conditions at 600, 625, 650, 675, 700 e 725 K and at 4310, 3128 e 2240 Pa of ethanol partial pressure. The mass of catalyst used in all tests were ca. 30 and 60 mg and the volumetric flow of ethanol saturated N2 was 2×10-6 m3 s-1. The compounds identified ethylene, acetaldehyde, diethyl ether, 1,3-butadiene, ethanol, ethyl acetate and selectivity with less than 2%, crotonaldehyde, butyraldehyde, butanol, acetone, propanol, propylene, methane, and methanol. The mass balance of the system was also performed and it was determined the values of the extent of reaction. The criteria for diffusion limitations were used in all cases. Calculations based on the experimental data suggest that data at 675, 700 and 725 K may be diffusion-limited. Deactivation tests were performed for 48 hours. The calculations of the overall reaction rate and turnover rate for all solid and all reaction conditions were also performed
Doutorado
Desenvolvimento de Processos Químicos
Doutora em Engenharia Quimica

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Sousa, HÃlvio Silvester Andrade de. "SÃntese, caracterizaÃÃo e propriedades catalÃticas de sÃlidos mesoporosos: influÃncia da estrutura sobre a desativaÃÃo de catalizadores aplicados a reforma do metano." Universidade Federal do CearÃ, 2012. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=13861.

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CoordenaÃÃo de AperfeiÃoamento de Pessoal de NÃvel Superior
Neste trabalho, aluminas mesoporosas dopadas com CeO2, MgO, ZrO2 ou La2O3 demonstraram que a estrutura dos sÃlidos influenciou no comportamento de desativaÃÃo de catalisadores na reforma seca do metano. Os sÃlidos foram caracterizados atravÃs de difraÃÃo de raios-X, anÃlise quÃmica, espectroscopia Raman, reduÃÃo termoprogramada, anÃlises texturais e termogravimÃtrica, microscopia eletrÃnica de transmissÃo e alta resoluÃÃo, antes e apÃs os testes catalÃticos. NÃquel, platina ou rutÃnio foram dispersos sobre os suportes porosos CeO2-Al2O3, ZrO2-Al2O3, MgO-Al2O3 e La2O3-Al2O3, formando distintas fases. Os catalisadores contendo rutÃnio ou platina foram em geral mais ativos na reforma seca do metano quando comparados aqueles contendo nÃquel, devido a maior dispersÃo das espÃcies de PtOx ou Ruo dispersas sobre MgAl2O4 ou CeAlO3. A resistÃncia Ã degradaÃÃo fÃsica dos sÃlidos contendo platina ou rutÃnio conduziu a um efeito do promotor para a formaÃÃo de espÃcies de carbono lÃbeis. Sobre o catalisador Ru/MgO-Al2O3, as nanopartÃculas de Ruo dispersas em MgAl2O4 foram mais acessÃveis as molÃculas de metano e diÃxido de carbono, apesar de serem as fontes para a formaÃÃo de carbono amorfo, grafite e nanotubos de carbono.
Mesoporous alumina doped with CeO2, MgO, ZrO2 or La2O3 demonstrated that the solid structure influenced on the deactivation behaviour of the catalysts in dry reforming of methane. Solids were characterized by X-ray diffraction, chemical analysis, Raman spectroscopy, termoprogrammed reduction, textural and thermogravimetric analyses and transmission electron microscopy, before and after the catalytic test. Nickel, ruthenium or platinum dispersed on porous CeO2-Al2O3, ZrO2-Al2O3, MgO-Al2O3 and La2O3-Al2O3 resulted in the formation of distinct phases. Catalysts possessing ruthenium or platinum were more active than the nickel counterparts due to the better dispersion of PtOx or Ruo on MgAl2O4 and CeAlO3 phases. The elevated resistance of ruthenium or platinum against physical degradation led to a promoting effect to labile carbon formation. Over Ru/MgO-Al2O3 catalyst, Ruo nanoparticles dispersed on MgAl2O4 were almost certainly accessible to methane and carbon dioxide molecules and the source supporting for the formation of such amorphous reactive carbon, graphite and carbon nanotubes, as well.

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Björk, Emma M. "Mesoporous Building Blocks : Synthesis and Characterization of Mesoporous Silica Particles and Films." Doctoral thesis, Linköpings universitet, Nanostrukturerade material, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-99858.

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Catalyst supports, drug delivery systems, hosts for nanoparticles, and solar cells are just some examples of the wide range of exciting applications for mesoporous silica. In order to optimize the performance of a specific application, controlling the material’s morphology and pore size is crucial. For example, short and separated particles are beneficial for drug delivery systems, while for molecular sieves, the pore size is the key parameter. In this thesis, mesoporous silica building blocks, crystallites, with hexagonally ordered cylindrical pores were synthesized, with the aim to understand how the synthesis parameters affect the particle morphology and pore size. The synthesis of the particles is performed using a sol-gel process, and in order to increase the pore size, a combination of low temperature, and additions of heptane and NH4F was used. By variations in the amounts of reagents, as well as other synthesis conditions, the particle morphology and pore size could be altered. Separated particles were also grown on or attached to substrates to form films. Also, a material with spherical pore structure was synthesized, for the first time using this method. It was found that a variation in the heptane concentration, in combination with a long stirring time, yields a transition between fiber and sheet morphologies. Both morphologies consist of crystallites, which for the fibers are joined end to end, while for the sheets they are attached side by side such that the pores are accessible from the sheet surface. The crystallites can be separated to a rod morphology by decreasing the stirring time and tuning the HCl concentration, and it was seen that these rods are formed within 5 min of static time, even though the pore size and unit cell parameters were evolving for another 30 min. Further studies of the effects of heptane showed that the shape and mesoscopic parameters of the rods are affected by the heptane concentration, up to a value where the micelles are fully saturated with heptane. It was also observed that the particle width increases with decreasing NH4F concentration, independent of heptane amount, and a platelet morphology can be formed. The formation time of the particles decrease with decreasing NH4F, and the growth mechanism for platelets was further studied. The pore sizes for various morphologies were altered by e.g. variations in the hydrothermal treatment conditions, or the method for removing the surfactants. The separated particles can be attached to substrates, either during the particle synthesis or by post grafting prior to calcination. The film formation during the one-pot-synthesis was studied and a formation mechanism including nucleation of elongated micelles on the substrate was suggested. During the post grafting film synthesis, the medium in which the particles are dispersed, as well as functionalization of both particle and substrate are crucial for the post grafting process. The pores are easily accessible independent of the method, even though they are aligned parallel to the substrate when the one-pot-method is used, while post grafting gives a perpendicular pore orientation. In summary, this work aims to give an understanding for the formation of the synthesized material, and how to tune the material properties by alterations in parameter space. Successful syntheses of four different particle morphologies and two new types of films were performed, and the pore size could easily be tuned by various methods.

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Yue, Wenbo. "Mesoporous crystalline metal oxides." Thesis, St Andrews, 2009. http://hdl.handle.net/10023/830.

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Liu, Yi. "Mesoporous silica/polymer nanocomposites." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/31739.

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Thesis (Ph.D)--Polymer, Textile and Fiber Engineering, Georgia Institute of Technology, 2010.
Committee Chair: Jacob. Karl; Committee Member: Griffin. Anselm; Committee Member: Tannenbaum. Rina; Committee Member: Thio. Yonathan S; Committee Member: Yao. Donggang. Part of the SMARTech Electronic Thesis and Dissertation Collection.

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Sheikh, Shehla Altaf. "Modification of mesoporous silicas." Thesis, University of Southampton, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.327599.

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Mehlhorn, Dirk, Rustem Valiullin, Jörg Kärger, and Ryong Ryoo. "Diffusion in mesoporous zeolites." Diffusion fundamentals 20 (2013) 96, S. 1, 2013. https://ul.qucosa.de/id/qucosa%3A13685.

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Mehlhorn, Dirk, Rustem Valiullin, Jörg Kärger, and Ryong Ryoo. "Diffusion in mesoporous zeolites." Diffusion fundamentals 16 (2011) 54, S. 1, 2011. https://ul.qucosa.de/id/qucosa%3A13795.

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Mehlhorn, Dirk, Rustem Valiullin, Jörg Kärger, and Ryong Ryoo. "Diffusion in mesoporous zeolites." Universitätsbibliothek Leipzig, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-183854.

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Borisova, Dimitriya. "Feedback active coatings based on mesoporous silica containers." Phd thesis, Universität Potsdam, 2012. http://opus.kobv.de/ubp/volltexte/2013/6350/.

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Metalle werden oft während ihrer Anwendung korrosiven Bedingungen ausgesetzt, was ihre Alterungsbeständigkeit reduziert. Deswegen werden korrosionsanfällige Metalle, wie Aluminiumlegierungen mit Schutzbeschichtungen versehen, um den Korrosionsprozess aktiv oder passiv zu verhindern. Die klassischen Schutzbeschichtungen funktionieren als physikalische Barriere zwischen Metall und korrosiver Umgebung und bieten einen passiven Korrosionsschutz nur, wenn sie unbeschädigt sind. Im Gegensatz dazu kann die Korrosion auch im Fall einer Beschädigung mittels aktiver Schutzbeschichtungen gehemmt werden. Chromathaltige Beschichtungen bieten heutzutage den besten aktiven Korrosionsschutz für Aluminiumlegierungen. Aufgrund ihrer Giftigkeit wurden diese weltweit verboten und müssen durch neue umweltfreundliche Schutzbeschichtungen ersetzt werden. Ein potentieller Ersatz sind Schutzbeschichtungen mit integrierten Nano- und Mikrobehältern, die mit ungiftigem Inhibitor gefüllt sind. In dieser Arbeit werden die Entwicklung und Optimierung solcher aktiver Schutzbeschichtungen für die industriell wichtige Aluminiumlegierung AA2024-T3 dargestellt Mesoporöse Silika-Behälter wurden mit dem ungiftigen Inhibitor (2-Mercaptobenzothiazol) beladen und dann in die Matrix anorganischer (SiOx/ZrOx) oder organischer (wasserbasiert) Schichten dispergiert. Zwei Sorten von Silika-Behältern mit unterschiedlichen Größen (d ≈ 80 and 700 nm) wurden verwendet. Diese haben eine große spezifische Oberfläche (≈ 1000 m² g-1), eine enge Porengrößenverteilung mit mittlerer Porenweite ≈ 3 nm und ein großes Porenvolumen (≈ 1 mL g-1). Dank dieser Eigenschaften können große Inhibitormengen im Behälterinneren adsorbiert und gehalten werden. Die Inhibitormoleküle werden bei korrosionsbedingter Erhöhung des pH-Wertes gelöst und freigegeben. Die Konzentration, Position und Größe der integrierten Behälter wurden variiert um die besten Bedingungen für einen optimalen Korrosionsschutz zu bestimmen. Es wurde festgestellt, dass eine gute Korrosionsschutzleistung durch einen Kompromiss zwischen ausreichender Inhibitormenge und guten Barriereeigenschaften hervorgerufen wird. Diese Studie erweitert das Wissen über die wichtigsten Faktoren, die den Korrosionsschutz beeinflussen. Somit wurde die Entwicklung effizienter, aktiver Schutzbeschichtungen ermöglicht, die auf mit Inhibitor beladenen Behältern basieren.
Metals are often used in environments that are conducive to corrosion, which leads to a reduction in their mechanical properties and durability. Coatings are applied to corrosion-prone metals such as aluminum alloys to inhibit the destructive surface process of corrosion in a passive or active way. Standard anticorrosive coatings function as a physical barrier between the material and the corrosive environment and provide passive protection only when intact. In contrast, active protection prevents or slows down corrosion even when the main barrier is damaged. The most effective industrially used active corrosion inhibition for aluminum alloys is provided by chromate conversion coatings. However, their toxicity and worldwide restriction provoke an urgent need for finding environmentally friendly corrosion preventing systems. A promising approach to replace the toxic chromate coatings is to embed particles containing nontoxic inhibitor in a passive coating matrix. This work presents the development and optimization of effective anticorrosive coatings for the industrially important aluminum alloy, AA2024-T3 using this approach. The protective coatings were prepared by dispersing mesoporous silica containers, loaded with the nontoxic corrosion inhibitor 2-mercaptobenzothiazole, in a passive sol-gel (SiOx/ZrOx) or organic water-based layer. Two types of porous silica containers with different sizes (d ≈ 80 and 700 nm, respectively) were investigated. The studied robust containers exhibit high surface area (≈ 1000 m² g-1), narrow pore size distribution (dpore ≈ 3 nm) and large pore volume (≈ 1 mL g-1) as determined by N2 sorption measurements. These properties favored the subsequent adsorption and storage of a relatively large amount of inhibitor as well as its release in response to pH changes induced by the corrosion process. The concentration, position and size of the embedded containers were varied to ascertain the optimum conditions for overall anticorrosion performance. Attaining high anticorrosion efficiency was found to require a compromise between delivering an optimal amount of corrosion inhibitor and preserving the coating barrier properties. This study broadens the knowledge about the main factors influencing the coating anticorrosion efficiency and assists the development of optimum active anticorrosive coatings doped with inhibitor loaded containers.

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Fozia, 1980. "Self-Assembled bridged polysilsesquioxane silica hybrids for dyes removal and controlled ibuprofen drug delivery = Híbridos polisililsesquioxanos auto-arranjados em pontes para remoção de corantes e liberação controlada de ibuprofeno." [s.n.], 2014. http://repositorio.unicamp.br/jspui/handle/REPOSIP/249117.

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Orientador: Pedro Luiz Onófrio Volpe
Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Química
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Resumo: Híbridos polisilsesquioxanos arranjados em pontos, foram sintetizados e caracterizados por análise elementar, espectroscopia de absorção na região do infravermelho, ressonância magnética nuclear no estado sólido, difração de raios X, microscopia eletrônica de varredura e transmissão eletrônica. Os dados de sorção/dessorção de nitrogênio para sílica pura, SBA-15 e os híbridos funcionalizados resultaram na isoterma do tipo IV com histerese do tipo H1. A estrutura da sílica mesoporosa ficou preservada após a pós-funcionalização com cadeias orgânicas. Pos-funcionalização da superfície com amina e outros grupos orgânicos contendo estrutura hidrofóbica, resultou numa diminuição da área da superfície 802,4-63,0 m2g-1 e volume de poros de 0,09 nm e aumento capacidade de carga de ibuprofeno a partir de 18,0 até 29% e um muito lento taxa de liberação ao longo do período de 72,5 h. Para investigar a taxa de liberação e o mecanismo a partir desses materiais híbridos sintetizados, zero-ordem, primeira ordem, Higuchi, Hixson-Crowell, Peppas e Korsmeyer-Peppas modelos cinéticos foram aplicados. Os materiais foram utilizados para a liberação controlada do fármaco ibuprofeno. Estes também foram avaliados quanto à capacidade de remover o corante aniônico azul reativo-15 e o corante catiônico verde brilhante de soluções aquosas. As sílicas modificadas apresentaram alta capacidade de carregamento do fármaco ibuprofeno e de sorção seletiva para o corante azul reativo 15. A sílica não modificada, SBA-15, apresentou alta capacidade de remover o corante verde brilhante. As isotermas de equilíbrio obtidas foram ajustadas aos modelos de Langmuir, Freundlich e Sips e os dados cinéticos foram ajustados aos modelos de pseudo-primeira-ordem e pseudo-segunda-ordem. Os resultados sugerem que os compostos organofuncionalizados de sílica podem ser um método simples, eficiente, barato e conveniente para a liberação controlada de fármacos e também para a remoção eficaz e seletiva de poluentes orgânicos tais como, corantes em soluções aquosas
Abstract: Bridged polysilsesquioxane silica hybrids, synthesized by the combination of SBA-15 type silica with new synthesized silylating agents containing bridged chains, were characterized by elemental analysis, absorption spectroscopy in the infrared region, nuclear magnetic resonance in the solid state, X-ray diffraction, scanning/transmission electron microscopy and thermogravimetry. The sorption/desorption of nitrogen to pure silica, SBA-15 and functionalized hybrids resulted in the isotherms of type IV with type H1 hysteresis. The structure of the precursor mesoporous silica was preserved after post-functionalization with bridged organic bridged chains. The precursor and its derivative silicas were ibuprofen-loaded for controlled delivery in simulated biological fluids. Surface functionalization with amine and other organic groups containing bridged hydrophobic structure resulted in significantly decreased surface area from 802.4 to 63.0 m2g-1 and pore volume to 0.09 nm, which ultimately increased the drug-loading capacity from 18.0 up to 29 % and a very slow release rate of ibuprofen over the period of 72.5 h. To investigate the release rate and mechanism from these synthesized hybrid materials, Zero-order, first-order, Higuchi, Hixson-Crowell and Peppas and Korsmeyer-Peppas kinetic models were applied. The synthesized materials were also evaluated for their ability to remove the anionic dye reactive blue-15 and cationic dye brilliant green from aqueous solutions. The hybrid silica showed selective sorption capacity for the anionic dye, reactive blue 15. The unmodified silica, SBA -15 showed high ability to remove the cationic dye, brilliant green from the aqueous medium. The obtained equilibrium isotherms were fitted to Langmuir, Freundlich and Sips models and the kinetic data were used to fit pseudo-first-order and pseudo-second-order. The results suggest that the organo-functionalized hybrid silicates could be a simple, efficient, inexpensive and convenient for the controlled release of drugs and for effective and selective removal of organic pollutants such as dyes from the aqueous solutions
Doutorado
Quimica Inorganica
Doutora em Ciências

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Khushalani, Deepa. "Studies of mesoporous inorganic materials." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp02/NQ35204.pdf.

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30

O'Brien, Stephen. "The chemistry of mesoporous materials." Thesis, University of Oxford, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.390532.

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Lotsi, Bertha. "Mesoporous Adsorbents for Perfluorinated Compounds." Digital Commons @ East Tennessee State University, 2020. https://dc.etsu.edu/etd/3729.

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Effective adsorbents for polyfluorinated compounds (PFCs) were successfully prepared. And they were tested in the adsorption of perfluorooctanoic and perfluorooctanesulfonic acids. Bridged silsesquioxanes containing secondary and tertiary amino groups were synthesized by sol-gel condensation of bis[3-(trimethoxysilyl)propyl]amine and bis[3-(methylamino)propyl]-trimethoxysilane in acidic media with surfactants. Obtained materials are mesoporous with a high BET surface area. They combine high structural stability with a high concentration of surface amino groups serving as adsorption sites. Batch adsorption tests demonstrated their extremely high adsorption capacity on PFCs: in some experiments, it reached up to 88% of the adsorbent weight. Adsorption of PFCs changed the surfaces of the adsorbent nanoparticles from hydrophilic to hydrophobic thus providing their agglomeration and floatability. Column tests showed fast adsorption of PFCs even at high concentrations and high flow rates. Obtained results can be used in the development of an effective filtration device for clean-up of water contaminated by PFCs.

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Wall, Jennifer H. "Spectroscopic characterisation of mesoporous materials." Thesis, University of York, 2011. http://etheses.whiterose.ac.uk/1963/.

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Commercially available inorganic solids and organically functionalised silicas and silica-polysaccharide composite materials synthesised in the laboratory were characterised by various techniques. These included direct infrared spectroscopic measurements, infrared and UV-visible probing techniques using probe molecules such as water, ammonia, d3-actonitrile, aniline, Reichardt’s dye and iodine and also by the application of the Knoevenagel condensation as a model reaction. As well as the information obtained about the surface activity of the solids, this review of techniques revealed the advantages and limitations of well-known and less frequently used methods. In particular, the use of iodine as a UV-visible probe molecule allowed the observation of differences between materials that are extremely difficult to analyse such as sodium carbonate and sodium acetate. However with current levels of knowledge about the electronic transitions of iodine adsorbed on surfaces, the results are not straight forward to interpret. The silica-polysaccharide composites also showed interesting properties, both in terms of their morphology and their chemistry and merit further study.

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Göbel, Ronald. "Hybridmaterialien aus mesoporösen Silica und ionischen Flüssigkeiten." Phd thesis, Universität Potsdam, 2011. http://opus.kobv.de/ubp/volltexte/2011/5402/.

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Die vorliegende Arbeit beschäftigt sich mit der Synthese und Charakterisierung mesoporöser monolithischer Silica und deren Hybridmaterialien mit Ionischen Flüssigkeiten (ILs, ionic liquids). Zur Synthese der Silicaproben wurde ein Sol-Gel-Verfahren, ausgehend von einer Präkursorverbindung wie Tetramethylorthosilicat angewendet. Der Katalysator mit der geringsten Basizität führte zum Material mit der kleinsten Porengröße und der größten spezifischen Oberfläche. Eine Kombination von porösen Silica mit ILs führt zur Materialklasse der Silica-Ionogele. Diese Hybridmaterialien verbinden die Eigenschaften eines porösen Festkörpers mit denen einer IL (Leitfähigkeit, weites elektrochemisches Fenster, gute thermische Stabilität) und bieten vielfältige Einsatzmöglichkeiten z.B. in der Katalyse- Solar- und Sensortechnik. Um diese Materialien für ihren Verwendungszweck zu optimieren, bedarf es deren umfassenden Charakterisierung. Daher wurde in der vorliegenden Arbeit das thermische Verhalten von Silica-Ionogelen unter Verwendung verschiedener 1-Ethyl-3-methylimidazolium [Emim]-basierter ILs untersucht. Interessanterweise zeigen die untersuchten ILs deutliche Änderungen in ihrem thermischen Verhalten, wenn diese in porösen Materialien eingeschlossen werden (Confinement). Während sich die untersuchten reinen ILs durch klar unterscheidbare Phasenübergänge auszeichnen, konnten für die entsprechenden Hybridmaterialien deutlich schwächer ausgeprägte Übergänge beobachtet werden. Einzelne Phasenübergänge wurden unterdrückt (Glas- und Kristallisationsübergänge), während z.B. Schmelzübergänge in verbreiterten Temperaturbereichen, zum Teil als einzeln getrennte Schmelzpeaks beobachtet wurden. Diese Untersuchungen belegen deutliche Eigenschaftsänderungen der ILs in eingeschränkten Geometrien. Über Festkörper-NMR-Spektroskopie konnte außerdem gezeigt werden, daß die ILs in den mesoporösen Silicamaterialien eine unerwartet hohe Mobilität aufweisen. Die ILs können als quasi-flüssig bezeichnet werden und zeigen die nach bestem Wissen höchste Mobilität, die bisher für vergleichbare Hybridmaterialien beobachtet wurde. Durch Verwendung von funktionalisierten Präkursoren, sowie der Wahl der Reaktionsbedingungen, kann die Oberfläche der Silicamaterialien chemisch funktionalisiert werden und damit die Materialeigenschaften in der gewünschten Weise beeinflußt werden. In der vorliegenden Arbeit wurde der Einfluß der Oberflächenfunktionalität auf das thermische Verhalten hin untersucht. Dazu wurden zwei verschiedene Möglichkeiten der Funktionalisierung angewendet und miteinander verglichen. Bei der in-situ-Funktionalisierung wird die chemische Funktionalität während der Sol-Gel-Synthese über ein entsprechend funktionalisiertes Silan mit in das Silicamaterial einkondensiert. Eine postsynthetische Funktionalisierung erfolgt durch Reaktion der Endgruppen eines Silicamaterials mit geeigneten Reaktionspartnern. Um den Einfluß der physikalischen Eigenschaften der Probe auf die Reaktion zu untersuchen, wurden pulverisierte und monolithische Silicamaterialien miteinander verglichen. Im letzten Teil der Arbeit wurde die Vielfältigkeit, mit der Silicamaterialien postsynthetisch funktionalisiert werden können demonstriert. Durch die Kenntnis von Struktur-Eigenschaftsbeziehungen können die Eigenschaften von Silica-Ionogelen durch die geeignete Kombination von fester und mobiler Phase in der gewünschten Weise verändert werden. Die vorliegende Arbeit soll einen Beitrag zur Untersuchung dieser Beziehungen leisten, um das Potential dieser interessanten Materialien für Anwendungen nutzen zu können.
This work describes the synthesis and characterization of mesoporous monolithic silica and its hybrid materials with ionic liquids (ILs). For synthesis of the silica samples a sol-gel method was used. The catalyst with the weakest basicity leads to the material with the smallest pore size and the largest specific surface area. Combination of porous silica with ILs yields silica-ionogels. These hybrid materials combine the properties of porous solids with the properties of ILs (which is e.g. high conductivity, wide electrochemical stability window, and good thermal stability) and therefore offer a variety of possible applications like catalysis, solar and sensing. To optimize these materials for specific applications there is a need to understand their structure-composition-property relations. For this reason the thermal behavior of silica-ionogels was studied using different 1-ethyl-3-methylimidazolium [Emim]-based ILs. Interestingly the ILs show a clear change in their thermal behavior upon confinement in porous silica. Whereas the pure ILs show distinct phase transitions, the hybrid materials exhibit considerably weaker phase transitions. Phase transitions are suppressed (glass- and crystallization phase transitions); melting transitions show multiple melting peaks. Furthermore solid-state NMR also shows that ILs in mesoporous silica exhibit unusual high mobility. The confined ILs can therefore be classified as quasi-liquid and represents to our best knowledge the highest mobility observed so far in ionogels. By using functionalized silane precursors and different reaction conditions the silica surface was chemically functionalized which further changes the material properties. In a final approach a post-synthetic functionalization was performed by reaction of the selected groups of a silica material with suitable reactants. To study the effect of the physical appearance on the characteristics of the final material, powdered and monolithic samples were studied. In the last part of the work the versatility of post-synthetic silica functionalization was demonstrated. The current work contributes to a better understanding of structure-property correlations, to improve the potential of these interesting materials for possible applications.

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S?, Guilherme Raymundo. "S?ntese seca de Ze?lita Beta a partir de precursores Mesoporosos tipo SBA-15 com diferentes m?todos de carboniza??o." Universidade Federal Rural do Rio de Janeiro, 2017. https://tede.ufrrj.br/jspui/handle/jspui/2245.

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Zeolites are microporous aluminosilicates and have assumed the position of most important catalysts in the chemical industry. However, these microporous materials have the limitation of the diffusion of molecules with larger kinetic diameter. Hybrid materials with hierarchical arrangement of pores in the micro-mesoporous scale have attracted great attention and interest in the last decades because they present acidic activity similar to the microporous zeolites and ordered pore diameter of the mesoporous materials. Beta zeolite can be used in a number of applications, including refining, petrochemical and biomass. The generation of mesopores in the beta zeolite enables higher yields by improving mass transfer in the FCC process. In this work, samples of the mesoporous material SBA-15 were synthesized and used as a source of silica for the synthesis of the mesoporous beta zeolite using the Dry Gel Conversion (DGC) technique. Samples of SBA-15 were submitted to three carbonization methods, using as carbon source sucrose, the organic template and both, in order to fill their pores with carbonaceous material and to prevent the collapse of its structure. The aluminization samples were studied at two times, before and during the dry gel synthesis. Three crystallization times were studied. X-ray diffraction (XRD), N2 adsorption / desorption, nuclear magnetic resonance (NMR), scanning electron microscopy (SEM) and infrared absorption spectroscopy with Fourier transform (FTIR) were used to characterize the samples. The results indicated that there was formation of zeolite beta presenting mesoporosity for the carbonization method that used only the template as carbon source. These samples showed BEA crystalline structure confirmed by XRD and FTIR analysis and formation of isotherms with type I and IV characteristics, with BET area greater than 500 m? / g, a volume of micropores close to 0.20 cm3 / g and with a volume of mesopores greater than 0.15 cm 3 / g. The other carbonization methods formed an amorphous phase, materials with low crystallinity and formation of polymorphs B and C over polymorph A. The samples presented the formation of mesoporosity did not present the mesopores present in the SBA-15, indicating collapse of the structure during the process of dry gel conversion
Ze?litas s?o aluminossilicatos microporosos e assumiram a posi??o de catalisadores mais importantes na ind?stria qu?mica. Entretanto, esses materiais microporosos possuem a limita??o da difus?o de mol?culas com di?metro cin?tico maior. Os materiais h?bridos com arranjo hier?rquico de poros na escala micro-mesoporosa atra?ram grande aten??o e interesses nas ?ltimas d?cadas pois apresentam atividade ?cida similar ?s ze?litas microporosas e di?metro de poros ordenados dos materiais mesoporosos. A ze?lita Beta pode ser usada em diversas aplica??es, incluindo o refino, a petroqu?mica e o processamento de biomassa. A gera??o de mesoporos na ze?lita beta possibilita maior rendimento melhorando a transfer?ncia de massa no processo de FCC. Neste trabalho foram sintetizadas amostras do material mesoporoso SBA-15 e utilizadas como fonte de s?lica para a s?ntese da ze?lita beta mesoporosa em meio seco utilizando a t?cnica de Dry Gel Conversion (DGC). As amostras de SBA-15 foram submetidas a tr?s m?todos de carboniza??o, utilizando como fonte de carbono sacarose, o direcionador de estrutura e ambos, com o objetivo de preencher seus poros com material carbon?ceo e evitar o colapso de sua estrutura. A aluminiza??o das amostras foi estudada em dois momentos, antes e durante a s?ntese do gel seco. Foram estudados tr?s tempos de cristaliza??o. Para caracteriza??o das amostras foram utilizadas as t?cnicas de difra??o de raios-X (DRX), adsor??o/dessor??o de N2, resson?ncia magn?tica nuclear (RMN), microscopia eletr?nica de varredura (MEV) e espectroscopia de absor??o no infra vermelho com transformada de Fourier (FTIR). Os resultados indicaram que houve a forma??o de ze?lita beta apresentando mesoporosidade para o m?todo de carboniza??o que utilizou apenas o direcionador de estrutura como fonte de carbono. Estas amostras apresentaram estrutura cristalina BEA confirmado pelas an?lises de DRX e FTIR e forma??o de isotermas com caracter?sticas do tipo I e IV, com ?rea BET superior a 500m?/g, um volume de microporos pr?ximos de 0,20 cm3/g e com um volume de mesoporos superior a 0,15 cm3/g. Os demais m?todos de carboniza??o formaram uma fase amorfa, materiais de baixa cristalinidade e com forma??o dos polimorfos B e C em detrimento ao polimorfo A. Os melhores resultados foram obtidos com o tempo de cristaliza??o de 48 horas. As amostras apresentando a forma??o de mesoporosidade n?o apresentaram os mes n?o apresentaram os mes n?o apresentaram os mesn?o apresentaram os mes n?o apresentaram os mesn?o apresentaram os mes n?o apresentaram os mes n?o apresentaram os mesn?o apresentaram os mes n?o apresentaram os mes n?o apresentaram os mes oporos presentes na SBA oporos presentes na SBA oporos presentes na SBA oporos presentes na SBA oporos presentes na SBA oporos presentes na SBA oporos presentes na SBAoporos presentes na SBAoporos presentes na SBAoporos presentes na SBA-15, indicando colapso da 15, indicando colapso da 15, indicando colapso da 15, indicando colapso da 15, indicando colapso da 15, indicando colapso da 15, indicando colapso da 15, indicando colapso da 15, indicando colapso da estrutura estrutura estrutura durante o processo de s?ntese seca

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Germano, Ana Fernanda de Souza. "Sílicas mesoporosas HMS e MCM-41 modificadas com grupos contendo nitrogênio e enxofre como adsorventes para íons metálicos em solução." Universidade Federal da Paraíba, 2012. http://tede.biblioteca.ufpb.br:8080/handle/tede/7077.

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Mesoporous organic-inorganic hybrids are promising candidates in the field of adsorption. In this work new adsorbents based on mesoporous silica MCM-41 and HMS types organofunctionalized with groups containing nitrogen and sulfur using the method after functionalization were synthesized. The HMS silica was obtained from neutral n-dodecylamine surfactant and modified with organosilanes containing one, two or three nitrogen atoms, then submitted to the functionalization reaction with mercaptoacetic acid or ethylene sulfide. The MCM-41 silica, obtained from CTAB template was modified with the organosilane containing one nitrogen atom and functionalized with carbon disulfide. The set of HMS functionalized silicas were used in the adsorption process of divalent cations Cd, Co, Cu, Ni and Pb from aqueous solution and kinetic study. All HMS and MCM-41 matrices were characterized through elemental analysis, thermogravimetry, surface area, infrared spectroscopy, nuclear magnetic resonance of 13C and 29Si and X-ray diffraction techniques. The elemental C, H, N and S analysis suggest success on the immobilization of ethylene sulfide, thioglycolic acid ligands, pointing probably to an ethylene sulfide molecules polymerization. The matrix MCM-41 showed a small degree functionalization, 0.09 mmol g -1 of sulfur anchored to the surface. HMS functionalized matrices demonstrated having adsorption capacity of Cd2+, Co2+, Cu2+, Ni2+ and Pb2+, being the best results observed for Cu2+ cation. All systems studied obey the pseudo-second order kinetics of reaction. The values of Cu2+ ions adsorbed on the matrices HMS containing one, two or three nitrogen atoms and mercaptoacetic acid were 0.86, 1.08 and 1.06 mmol g-1, respectively. For matrices containing one, two or three nitrogen atoms and ethylene sulfide, values were 0.83, 1.38 and 1.01 mmol per gram, respectively.
Híbridos mesoporosos orgânico-inorgânicos são candidatos promissores na área de adsorção. Neste trabalho, foram sintetizados novos adsorventes baseados em sílicas mesoporosas do tipo HMS e MCM-41 organofuncionalizadas com grupos contendo nitrogênio e enxofre empregando o método pós funcionalização. A sílica HMS foi obtida a partir do direcionador n-dodecilamina e modificada com os organossilanos contendo um, dois ou três átomos de nitrogênio, em seguida submetidas a reações de funcionalização com ácido tioglicólico ou etilenossulfeto. A sílica MCM-41, obtida a partir do direcionador CTAB, foi modificada apenas com o organossilano contendo um átomo de nitrogênio e funcionalizada com dissulfeto de carbono. O conjunto de sílicas HMS funcionalizadas foram aplicadas em processos de adsorção dos cátions divalentes Cd, Co, Cu, Ni e Pb em solução aquosa, sendo realizado o estudo cinético. As matrizes HMS e MCM-41 puras, modificadas e funcionalizadas foram caracterizadas através das técnicas de análise elementar, termogravimetria, determinação de área superficial, espectroscopia na região do infravermelho, ressonância magnética nuclear de 13C e 29Si e difratometria de raios-X. Os dados de análise elementar de C, H, N e S sugerem o sucesso da imobilização dos ligantes ácido tioglicólico e etilenossulfeto apontando para possível polimerização das moléculas de etilenossulfeto. A matriz MCM-41 apresentou pequeno grau de funcionalização, 0,09 mmol g-1 de enxofre ancorado à superfície. As matrizes HMS funcionalizadas demonstraram capacidade para adsorção dos cátions Cd2+, Co2+, Cu2+, Ni2+ e Pb2+, sendo os melhores resultados verificados para o cátion Cu2+. Todos os sistemas estudados obedecem à cinética de reação de pseudo-segunda ordem. As quantidades dos cátions Cu2+ fixos adsorvidos nas matrizes HMS contendo um, dois ou três átomos de nitrogênio e o ligante ácido tioglicólico foram: 0,86; 1,08 e 1,06 mmol g-1, respectivamente. Para as matrizes contendo um, dois ou três átomos de nitrogênio e o ligante etilenossulfeto os valores foram: 0,83; 1,38 e 1,01 mmol por grama, respectivamente.

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Fernandes, Glauber Jos? Turolla. "Reciclagem qu?mica de Polietileno utilizando S?lica Mesoporosa tipo SBA-15 avalizada por Termogravimetriae Espectrometria de Massas." Universidade Federal do Rio Grande do Norte, 2010. http://repositorio.ufrn.br:8080/jspui/handle/123456789/17787.

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The chemical recycling of polyolefins has been the focus of increasing attention owing potential application as a fuel and as source chemicals. The use of plastic waste contributes to the solution of pollution problems.The use of catalysts can enhance the thermal degradation of synthetic polymers, which may be avaliated by Themogravimetry (TG) and mass spectrometry (MS) combined techniques. This work aims to propose alternatives to the chemistry recycling of low-density polyethylene (LDPE) on mesoporous silica type SBA-15 and AlSBA-15.The mesoporous materials type SBA-15 and AlSBA-15 were synthesized through the hydrothermal method starting from TEOS, pseudobohemite, cloridric acid HCl and water. As structure template was used Pluronic P123. The syntheses were accomplished during the period of three days. The best calcination conditions for removal of the organic template (P123) were optimized by thermal analysis (TG/DTG) and through analyses of Xray diffraction (XRD), infrared spectroscopy (FT-IR), nitrogen adsorption and scanning electron microscopy (SEM) was verified that as much the hydrothermal synthesis method as the calcination by TG were promising for the production of mesoporous materials with high degree of hexagonal ordination. The general analysis of the method of Analog Scan was performed at 10oC/min to 500 oC to avoid deterioration of capillary with very high temperatures. Thus, with the results, we observed signs mass/charge more evident and, using the MID method, was obtained curve of evolution of these signals. The addition of catalysis produced a decrease in temperature of polymer degradation proportional to the acidity of the catalyst. The results showed that the mesoporous materials contributed to the formation of compounds of lower molecular weight and higher value in the process of catalytic degradation of LDPE, representing an alternative to chemical recycling of solid waste
A reciclagem qu?mica de poliolefinas tem sido foco de crescente aten??o, devido ao seu uso potencial como combust?vel e como fonte de produtos qu?micos. O aproveitamento de res?duos pl?sticos contribui para a solu??o dos problemas de polui??o. O uso de catalisadores adequados pode facilitar a degrada??o t?rmica de pol?meros sint?ticos, que pode ser avaliada por termogravimetria e espectrometria de massas. Este trabalho teve como objetivo avaliar uma alternativa de reciclagem qu?mica de polietileno de baixa densidade (PEBD) sobre s?lica mesoporosa tipo SBA-15 e AlSBA-15 utilizando termogravimetria e espectrometria de massas.Os materiais mesoporosos tipo SBA-15 e AlSBA- 15 foram sintetizados atrav?s do m?todo hidrot?rmico partindo de tetraetilortosilicato TEOS, pseudobohemita, ?cido clor?drico - HCl e ?gua destilada. Como direcionador estrutural foi utilizado Pluronic P123 (copol?mero tribloco). As s?nteses foram realizadas durante um per?odo de tr?s dias. As melhores condi??es de calcina??o para remo??o do direcionador org?nico (P123) foram otimizadas por an?lise t?rmica (TG/DTG) e atrav?s de an?lises por difra??o de raios X (DRX), espectroscopia na regi?o do infravermelho (FTIR), adsor??o de nitrog?nio e microscopia eletr?nica de varredura (MEV) se verificou que tanto o m?todo de s?ntese hidrot?rmico, como tamb?m as condi??es de calcina??o baseadas nos estudos cin?ticos por termogravimetria (TG) foram promissores ? produ??o de materiais mesoporosos com alto grau de ordena??o hexagonal. Os estudos de decomposi??o e evolu??o de gases foram realizados em uma termobalan?a acoplada a um espectr?metro de massas. A an?lise geral das amostras com o m?todo de Scan Analog foi realizada a 10?C/min at? 500?C para n?o deteriorar o capilar com temperaturas muito altas. Assim, com os resultados foi poss?vel observar os sinais massa-carga mais evidentes e, empregando o m?todo MID, foi obtida a curva de evolu??o desses sinais. A adi??o de catalisadores produziu uma diminui??o na temperatura de degrada??o do pol?mero proporcional ? acidez do catalisador. Os resultados obtidos, mostraram que os materiais mesoporosos contribu?ram para a forma??o de compostos de menor massa molecular e maior valor agregado no processo de degra??o catal?tica do PEBD, representando uma alternativa de reciclagem qu?mica destes res?duos s?lidos

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Reynhardt, Jan Petrus Karel. "Carbonylation catalysts based on metal complexed PAMAM-dendrimers supported on mesoporous and periodic mesoporous silica supports." Thesis, University of Ottawa (Canada), 2005. http://hdl.handle.net/10393/29253.

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This thesis describes the synthesis and characterization of various polyamidoamine (PAMAM) dendrimer moieties supported on amorphous mesoporous and periodic mesoporous silica supports. The surface characteristics of the supports are investigated using various methods and found to be intricately involved in the success of the dendrimer synthesis. The dendrimers are phophinomethylated and complexed with either palladium or rhodium and used as catalysts for carbonylation reactions. The palladium complexed C6-PAMAM dendrimers supported on aminopropyl silica gel are recyclable catalysts for the hydroesterification of olefins and turnover numbers (TON) of up to 1200 are possible. C2-PAMAM dendrimers supported on LPMCM-41 and Davisil are complexed with rhodium and used as catalysts for the hydroformylation reaction of olefins. These catalysts show how the pore geometry influences the activity and recyclability of the catalysts. The dendrimer-rhodium complexes supported on LPMCM-41 exhibit very high activity and a TOF of up to 1800 h-1 are observed for the hydroformylaton of 1-octene. These catalysts can be recycled effectively by simple filtration. A negative dendrimer effect is observed with the higher generations exhibiting lower activity than the lower generations. The dendrimer-rhodium complexes supported on Davisil also exhibit very high activity and a TOF of up to 1700 h-1 are observed for the hydroformylation of 1-octene. The activity of these catalysts are less dependent on the generation than the LPMCM-41 dendrimers, and excellent activity is observed up to the third generation for the hydroformylation reaction of 1-octene.

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Li, Yan. "Periodic mesoporous organosilicas with functional chromophores." Diss., Ludwig-Maximilians-Universität München, 2012. http://nbn-resolving.de/urn:nbn:de:bvb:19-173286.

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Jackson, Dominic. "Organic functionalisation of hexagonal mesoporous silica." Thesis, University of York, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.341112.

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Schillo, Melissa C. "Mesoporous Inorganic Membranes for Water Purification." The Ohio State University, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=osu1313586746.

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Meoto, Silo, and Marc-Olivier Coppens. "Anodic alumina-mesoporous silica hybrid membranes." Universitätsbibliothek Leipzig, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-184904.

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Ronhovde, Cicily J. "Biomedical applications of mesoporous silica particles." Diss., University of Iowa, 2017. https://ir.uiowa.edu/etd/5837.

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Mesoporous silica particles are of significant interest for biomedical applications due to their good general biocompatibility compared to other nanoparticle matrices such as quantum dots, high specific surface areas up to 1000 m2/g, and extreme synthetic tunability in terms of particle size, pore size and topology, core material, and surface functionalization. For one application, drug delivery, mesoporous silica nanoparticles (MSNs) of two pore structures, MCM-41 – parallel, hexagonally ordered pores approximately 3 nm in diameter – and wormhole (WO) – interconnected, disordered pores also approximately 3 nm in diameter – were synthesized with particle diameters under 100 nm. Additionally, a magnetic Fe3O4 nanoparticle core was incorporated into Fe3O4-core WO-MS-shell particles. The particles were loaded with doxorubicin, a chemotherapeutic, and the drug release into phosphate buffered saline (PBS, 10 mM, pH 7.4) at 37 °C was monitored by fluorescence spectroscopy. The data were fit to three models: Korsmeyer-Peppas, first order exponential release, and Weibull. The Korsmeyer-Peppas model provided useful information concerning the kinetics and mechanism of drug release from each MSN type. A small but statistically significant difference in the release kinetics was found due to the different pore topologies. A much larger kinetic effect was observed due to the inclusion of an iron oxide core. Applying a static magnetic field to the Fe3O4-core WO-MS shell particles did not have a significant impact on the doxorubicin release. This is the first time that the effects of pore topology and iron oxide core have been isolated from pore diameter and particle size for these materials. In vitro cell studies were conducted to determine the cytotoxicity of the bare and doxorubicin-loaded materials against three cancerous cell lines – A549 human lung carcinoma cells, HEC50CO human endometrial cancer cells, and CT26 mouse colon cancer cells. The MCM-41 and WO MSNs generally displayed similar toxicities within each cell line, and the Fe3O4-core WO-MS shell particles were less toxic. Doxorubicin-loaded particles generally displayed greater toxicity than bare MSNs, but the A549 cells were very resistant to all concentrations of MSNs tested. For another biomedical application, tissue phantom development, mesoporous silica particles with approximately 10 μm diameters and C18 surface functionalization were evaluated for their use as a substrate for optical tissue phantoms. Tissue phantoms are synthetic imitations of biological material, and C18-modified silica provides a substrate that is simple to load with optically active biological molecules. The molecules are then hydrophobically trapped to maintain a clear optical boundary between the biological loading within the particle and an aqueous suspension gel. Several preparation techniques were evaluated for the dispersal of hydrophobic particles in aqueous media, and qualitative analysis indicated that surfactant coating of the outer surface could fully disperse the hydrophobic particle while maintaining the clear optical boundary. A novel analysis was developed to provide a single numerical indicator of clustering for a quantitative assessment of particle dispersal in tissue phantoms.

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TIDDIA, MARIAVITALIA. "Hybrid Mesoporous and Microporous Materials Characterisation." Doctoral thesis, Università degli Studi di Cagliari, 2019. http://hdl.handle.net/11584/259900.

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My thesis research is undertaken to address various challenges in the study of porous hybrid materials. The effect of the insertion of polymer in porous material via an electrochemical process, the analysis of the photocurrent generated by developing a hybrid p-n junction, the stability and the resistance added to the pristine material by the process and the definition of a protocol for mass spectrometry analysis of porous materials and buried interfaces will be presented in the seminar. Two popular analysis techniques; electrochemistry and mass spectrometry, explored the potential to analyse organic inorganic hybrid materials and interfaces using different polymers and different inorganic substrates. Electrochemical and optical study made on porous silicon grafted with a conducting polymer, properties like resistance to attack by basic solution and photocurrent generation will be presented and explained. The possibility to understand how the polymer is attached to the pore walls is investigated by mass spectrometry imaging. This technique requires refinement of measurement parameters for this class of materials, by using models with similar composition and geometry. To do this, I used a focused ion beam (FIB) for milling the surface of a porous micrometric matrix applying a particular cleaning procedure to recover the damaged polymeric component. This method has been successfully applied to other devices to highlight the effectiveness of this technique in section. These studies provide the essential metrological foundation to address frontier issues in surface and nanoanalysis and extend the measurement capabilities of secondary ion mass spectrometry.

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Solberg, Sean. "Synthesis and Characterization of New Mesoporous Materials and their Application in Catalysis and Adsorption." ScholarWorks @ UVM, 2008. http://scholarworks.uvm.edu/graddis/219.

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Materials chemistry represents a very broad, but extremely applicable field of study to everyday life. Since many of the useful applications of these ‘sponge-like’ porous materials are dependent on the amount of surface area, the development and use of highly-porous materials with tremendous surface areas significantly enhances the effectiveness of these materials. Examples of such traditional applications include adsorption, separation, and catalytic applications. The study of porous materials has brought the ability to accurately synthesize and modify these materials to meet specific application requirements. The field of porous materials has been traditionally dominated by many “natural” or traditionally inspired materials such as zeolites and porous carbon materials. Although very effective, these materials have very small pore-windows that prevent their application in all but very small molecule applications. This limitation drove the development of large pore-window materials in the 1990s, known as mesoporous materials. Mesoporous materials are defined by IUPAC as possessing pore-openings between 20 and 500 Å. This much broader size-range spurred the use of mesoporous materials into other applications, including large-molecule heterogeneous catalysis and biomedical applications. Chapter one of this dissertation presents an introduction to the field of mesoporous materials, with both silica based and carbon based materials covered. Chapter two and three cover the development of a new mesoporous/microporous silica material. The purpose of this material was to combines the advantages of both types of materials, namely the large pore-opening of mesoporous materials with the stability of a traditional microporous material. The combined material, named MMM-2, is doped with titanium heteroatoms for use in catalytic reactions. The chapter presents a thorough study of the synthesis and characterization of MMM-2 along with its application as a more effective catalysis in the oxidation of cyclohexene. Chapters four and five further extend the work on the MMM-2 materials by incorporating aluminum into the silica framework to form a solid acid-catalyst. Again, thorough treatment is given to the synthesis and characterization of this material. Al- MMM-2 is shown to possess unique structural properties relative to the pure mesoporous and microporous materials that it is related to. Moreover, Al-MMM-2 is shown to be more effective in acid-catalysis reactions as well as possessing improved structural stability upon the reuse of the material in successive reaction cycles. Chapters six and seven cover the use of the mesoporous material, APMS in the adsorption and delivery of DNA. APMS, which is spherically shaped, is shown to be an effective adsorbant of DNA into its internal pores with adsorption determined to be dependent on several factors such as the ionic environment, pore size, and surface characteristics. Finally, chapter eight covers the templated synthesis and characterization of a new, spherically shaped, porous carbon material. This material, based upon APMS, provides tremendous increase in surface area and pore volume relative to its silica parent. The large increase in the physical properties provides enhanced adsorption of DNA.

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45

Klein, Nicole. "Synthese und Charakterisierung neuer mesoporöser und flexibler metallorganischer Gerüstverbindungen und deren Anwendung als Gasspeichermaterialien." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2012. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-98526.

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Die Entwicklung und Synthese im Bereich neuartiger poröser Systeme, im speziellen Metallorganische Gerüstverbindungen (engl.: Metall-organic Frameworks; MOFs), wird weltweit in vielen Forschergruppen intensiv bearbeitet. Aufgrund der Möglichkeit, dass sich die Materialeigenschaften individuell designen lassen und letztendlich spezifische Eigenschaften für eine ausgewählte Anwendung bereitgestellt werden können, stellen MOFs für einen weiten Forscherkreis eine interessante Materialienklasse dar. Im Rahmen dieser Arbeit stand die Synthese von neuartigen MOFs im Vordergrund, welche geeignete Eigenschaften für eine effiziente Speicherung von Gasen im Nieder- als auch im Hochdruckbereich besitzen. Dabei wurde zum einen Augenmerk auf die Synthese mesoporöser MOF-Systeme gelegt. Hier lag die größte Herausforderung darin, die erhaltenen hochporösen Materialien in einer stabilen gastfreien Form zu erhalten. Ein weiterer Schwerpunkt war die Untersuchung von flexiblen MOF-Verbindungen und deren Eigenschaften in Abhängigkeit der Synthesebedingungen und der adsorbierten Spezies. Auf Basis der Copolymerisation verschiedener multifunktioneller Linkermoleküle konnten zwei mesoporöse Verbindungen und dazugehörige Isomorphe synthetisiert werden (DUT-6, DUT-23; DUT = Dresden University of Technology). Mit diesen Verbindungen konnte über die Kombination von unterschiedlich funktionellen Linkermolekülen eine erhöhte Netzwerkstabilität und damit einhergehend erhöhte Porosität erhalten werden. Sämtliche Verbindungen zeigen ausgezeichnetes adsorp-tives Verhalten und können aufgrund ihrer verschiedenen Eigenschaften in Bereichen der Hochdruckadsorption, Katalyse oder enantioselektiven Trennung Einsatz finden. Im zweiten Teil der Arbeit wurde das flexible Verhalten der „pillar-layer“ Verbindungen DUT-8(M) (M = Ni, Co, Zn, Cu) näher untersucht. Diese isomorphe Reihe zeichnet sich durch ihre hohe Netzwerkflexibilität in Abhängigkeit der integrierten Gastmoleküle sowie dem vorliegendem Metall-Dimer aus. DUT-8(M) zeigt unterschiedliche Adsorptionseigenschaften und unterschiedliches Stabilitäts- sowie Flexibilitätsverhalten.

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46

Xu, Yeping. "Synthesises of mesoporous materials and studies of host-guest interaction in mesoporous carbon by solid state NMR." Berlin mbv, Mensch-und-Buch-Verl, 2009. http://d-nb.info/995894957/04.

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Cassimiro, Vinicius Roberto de Sylos. "Zircônia céria mesoporosa para células de combustível e catalisadores." Universidade de São Paulo, 2015. http://www.teses.usp.br/teses/disponiveis/43/43134/tde-07012016-121443/.

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Os materiais à base de céria (CeO2) e zircônia (ZrO2) estão presentes em diversas aplicações tecnológicas, destacando-se como anodo de células de combustível de óxido sólido (SOFC) e em catálise, tanto para a produção de hidrogênio, como na automotiva (Three-Way Catalysis). A solução sólida ZrxCe1-xO2- é de especial interesse, pois apresenta melhor estabilidade térmica e maior capacidade de armazenamento de oxigênio (OSC), quando comparada com os óxidos não dopados. Os materiais mesoporosos (poros de 2 a 50 nm) possuem elevada área superficial e permeabilidade a gases, características estas importantes para o desempenho das SOFCs e dos processos de catálise. Neste trabalho, zircônia-céria (Zr0,1Ce0,9O2-) mesoporosa foi sintetizada pelo processo sol-gel, utilizando, como precursores, os cloretos inorgânicos (ZrCl4 e CeCl3.7H2O), o copolímero em bloco P123 (PEO20PPO70PEO20) como direcionador de estrutura e o TIPB (tri-isopropil-benzeno) como agente dilatador. A solução passou por tratamento hidrotérmico durante 48h a 80°C, com posterior calcinação a 400°C para a remoção do polímero, resultando no óxido cristalizado. Na análise foram utilizadas as técnicas: difração de raios X em alto ângulo (XRD), espalhamento de raios X a baixo ângulo (SAXS), isotermas de adsorção de nitrogênio (NAI) e microscopia eletrônica de varredura e transmissão (SEM e TEM). Os resultados mostraram que o material possui elevada área superficial (110m2/g), mesoporos de várias dimensões, atingindo valores médios em torno de 30 nm, fase majoritariamente cúbica Fm3m e, em menor proporção, tetragonal P42/nmc. As micrografias revelaram que o óxido está totalmente nano-cristalizado, com os poros tipo fendas e uma mesoporosidade secundária com distribuição de tamanhos menor e mais estreita. Quatro amostras foram sintetizadas com diferentes razões em massa TIPB/P123 (0, 1, 2 e 4), de forma que foi possível verificar um aumento na dimensão dos poros devido à inclusão do dilatador. As demais propriedades estruturais e morfológicas mantiveram-se inalteradas entre todas as amostras, mesmo com diferentes quantidades de TIPB.
The ceria (CeO2) and zirconia (ZrO2) based materials are present in several technological applications, mainly as Solid Oxide Fuel Cells (SOFC) anodes and catalysts, for hydrogen production and automotive converter (Three-Way Catalysis). The solid solution ZrxCe1-xO2- has attracted special attention, since it shows better thermal stability and higher oxygen storage capacity (OSC), if compared to the non-doped oxides. The mesoporous materials (pores of 2 to 50 nm) show high surface area and gas permeability, important properties for SOFCs and catalysts efficiency. In this work, mesoporous ceria-zirconia (Zr0,1Ce0,9O2-) was synthesized by a sol-gel route using inorganic chlorides (ZrCl4 e CeCl3.7H2O) as precursors, block copolymer P123 (PEO20PPO70PEO20) as template and TIPB (tri-isopropyl-benzene) as swelling agent. The solution was submitted to hydrothermal treatment for 48h at 80°C and calcined at 400°C to remove the template, resulting in the crystallized oxide. The characterization was performed by X-ray diffraction at high angles (XRD), small angle X-ray scattering (SAXS), nitrogen adsorption isotherms (NAI) and transmission and scanning electron microscopy (TEM and SEM). The results showed that the material has high surface area (110m2/g), a wide pore size distribution with mean values around 30 nm, predominant cubic phase Fm3m and, in less quantity, tetragonal P42/nmc. The micrographs revealed that the oxide is totally nano-crystallized, having pores with slit shape and a secondary smaller mesoporosity with a narrow size distribution. Four samples were produced with different TIPB/P123 mass rate (0, 1, 2, 4), therefore was possible to verify the pore size expansion due to the swelling addition. The structural and morphological properties remained unchanged, even with different quantities of TIPB.

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Grünker, Ronny. "Hochporöse und flexible metallorganische Gerüstverbindungen basierend auf Stickstoff-haltigen Carboxylat-Liganden." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2013. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-104535.

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Metallorganische Gerüstverbindungen (engl.: Metal-organic Framework, MOFs) haben sich in den letzten Jahren neben Zeolithen, Aktivkohlen und anderen als eine weitere Klasse poröser Materialien etabliert. Die Möglichkeit des individuellen Designs von Eigenschaften wie Porengröße und -geometrie, innerer Oberfläche und Porenvolumen, der Hydrophilie und Funktionalität machen diese Materialklasse zum Gegenstand der Forschung in den vielfältigsten Gebieten. Darüber hinaus besitzen sie unter porösen Materialien exklusiv die Eigenschaft der definierten strukturellen Flexibilität, welche in Kombination mit bereits genannten Eigenschaften eine weitere Vielzahl an neuen möglichen Anwendungen erahnen lässt. Die Faszination dieser strukturellen Flexibilität von MOFs sowie die Möglichkeit der Kontrolle dieser Eigenschaft sollten im Fokus der Betrachtung stehen. Zur Integration von Flexibilität in dreidimensionale Netzwerke wurde als Strategie der Einsatz von semi-flexiblen Linkermolekülen gewählt. Eine potentielle Molekülklasse für diese Art der Untersuchung stellen Triarylaminverbindungen dar, da sie trotz ihrer durchgängigen sp2-Hybridisierung über ein gewisses Maß an konformeller Flexibilität verfügen. So wurde über einen präparativ sehr guten Zugang der tetrafunktionelle H4benztb-Linker (Abbildung 1a) generiert. Durch die Kombination dieser Tetracarbonsäure mit Metall-Clustern unterschiedlicher Konnektivität resultierten acht strukturell unterschiedliche MOFs, wodurch an diesen Verbindungen Aussagen über Struktur-Eigenschafts-Beziehungen getroffen werden können. Ein weiterer Schwerpunkt dieser Arbeit war die kostengünstige Darstellung komplexer nicht-kommerzieller Liganden und daraus resultierende hochporöse MOFs sowie Untersuchungen zu deren Stabilität und Speicherkapazität für verschiedene Gase im Hochdruckbereich. Durch die Reaktion des H4benztb-Liganden mit Zinknitrat unter variierenden Synthesebedingungen konnten drei Netzwerke unterschiedlich hoher Konnektivität erhalten werden. DUT 10(Zn) (Zn2(benztb)2(H2O)2), basierend auf dem vierfach verknüpfenden dimeren Schaufelrad-Konnektor, zeigt mit einem (4,4)-Netzwerk dabei den geringsten Verzweigungsgrad. Daraus resultierend zeigt dieses Material eine sehr große strukturelle Flexibilität beim Entfernen des in den Poren vorliegenden Lösungsmittels sowie bei der Adsorption von CO2 bei -78°C bis 1 bar. Wird die Netzwerkkonnektivität durch den Einsatz eines sechsfach verknüpfenden [Zn4O]6+-Clusters erhöht, so zeigt das resultierende (4,6)-Netzwerk von DUT-13 (Zn4O(benztb)3/2) eine größere strukturelle Stabilität beim Entfernen des Lösunsgmittels sowie bei der Adsorption von Gastmolekülen im überkritischen Zustand. Für gasförmige Adsorptive zeigt das Netzwerk bei der Adsorption ein hochgradig flexibles Verhalten. Im Fall von N2 konnte über in situ-PXRD-Physisorptionsmessungen eine bislang noch nie beobachtete kristallin-amorph-kristallin-amorph-Transformation während eines Physisorptionszyklus beobachtet werden, was zeigt, dass DUT-13 über ein sog. Formgedächtnis verfügt und nach einer Amorphisierung erneut in seine ursprüngliche kristalline Form zurückkehrt. Neben der Erhöhung der Netzwerkkonnektivität wurde auch der Einfluss der partiellen Substitution des semi-flexiblen H4benztb gegen rigide Linker auf die Netzwerkflexibilität untersucht. Durch die Copolymerisationsstrategie des H4benztb mit der starren 1,3,5-Benzentribenzoesäure (H3btb) konnte DUT 25 (Zn4O(btb)2/3(benztb)) erhalten werden. Aufgrund der geringen Erhöhung der Rigidität der Verbindung zeigt dieses (3,4,6)-Netzwerk keinerlei strukturelle Flexibilität während der Aktivierung, der Adsorption von verschiedenen Gasen sowie von Gastmolekülen aus der Flüssigphase. Man erhält ein starres Material mit einer spezifischen inneren Oberfläche (SSA) von 4670 m2g-1 und einem totalen Porenvolumen (VP) von 2.22 cm3g-1. Aufbauend auf den positiven Ergebnissen der Copolymerisationsstrategie von DUT-25, wurde versucht, diese auf weitere kostengünstige Linkersysteme zur Synthese hochporöser MOF-Verbindungen auszuweiten. Durch eine effiziente und günstige Synthese einer Tricarbonsäure auf Amidbasis, 4,4´,4´´-[1,3,5-Benzentriyltris(carbonylimino)]trisbenzoesäure (H3btctb), und deren Kombination mit der linearen 4,4´-Biphenyldicarbonsäure (H2bpdc) und Zinknitrat wurde ein neues mesoporöses Koordinationspolymer DUT-32 (Zn4O(btctb)4/3(bpdc)) mit hierarchischem Porensystem erhalten. Dieses System konnte nur unter Zuhilfenahme von überkritischem CO2 in einen porösen lösungsmittelfreien Zustand überführt werden. Hierbei konnten die gravierenden Einflüsse verschiedener Parameter während der Trocknung (Lösungsmittel, Verweilzeit) auf die porösen Eigenschaften des resultierenden Materials aufgezeigt werden. Der Austausch des Reaktionslösungsmittels gegen Ethanolabs. und anschließende überkritische Trocknung führte zu einem amorphen porösen Material mit einem Typ-IV-N2-Isothermenverlauf und einer daraus berechneten spezifischen Oberfläche von 840 m2g-1, einem Mikroporen- sowie einem totalen Porenvolumen von 0.36 bzw. 2.91 cm3g-1. Erfolgt die Trocknung aus einem Lösungsmittel mit möglichst geringen Wechselwirkungen mit dem Netzwerk (Aceton, Amylacetat), so zeigt das resultierende kristalline Material nach einer CO2-Austauschzeit von drei Tagen gänzlich andere texturelle Eigenschaften mit einem Typ-I-N2-Isothermenverlauf, einer spezifischen Oberfläche von 5080 m2g-1 sowie einem totalen Porenvolumen von 2.27 cm3g-1. Wird diese Verweil- und damit die Austauschzeit im flüssigen CO2 weiter auf sieben Tage erhöht, steigt auch die Qualität/Porosität des Materials und man erhält eine Verbindung mit der bislang höchsten beschriebenen spezifischen Oberfläche (SSA = 7192 m2g-1), extrem hohem spezifischen Porenvolumen (VP = 3.16 cm3g-1) und hervorragenden Eigenschaften für die Gasspeicherung.

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Wattanakit, Chularat. "Élaboration et application de matériaux poreux : études théoriques et expérimentales." Phd thesis, Université Sciences et Technologies - Bordeaux I, 2013. http://tel.archives-ouvertes.fr/tel-00912339.

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Dans ce travail nous étudions l'élaboration, la caractérisation et les applications de différents matériaux poreux. L'étude est organisée en trois parties majeures: la synthèse de zéolithes micro/mesoporeux et leur application potentielle dans l'industrie pétrochimique, l'étude théorique de mécanismes réactionnels sur des zeolites microporeux, et le design de métaux mesoporeux avec une chiralité intrinsèque de leur surface interne. Ces matériaux poreux montrent des propriétés excellentes, notamment pour des applications potentielles en catalyse et comme interfaces chirales.

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Xia, Yanfeng. "SYNTHESIS OF ORDERED MESOPOROUS MATERIALS VIA MICROWAVE PROCESSING AND HIGHLY HETEROATOM DOPED ORDERED MESOPOROUS CARBONS FOR ENERGY STORAGE." University of Akron / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=akron15270948387105.

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