Teses / dissertações sobre o tema "Copper Spinel"

Le développement technologique visant à construire une société utilisant l'hydrogène comme moyen d'énergie, avec une faible charge environnementale et un rendement élevé, est nécessaire de toute urgence. Toutefois, l'hydrogène étant inflammable, les problèmes de sécurité liés à son stockage et à son transport limitent son utilisation en tant que combustible. L’utilisation des transporteurs organiques liquides d'hydrogène (TOLHs, ou LOHCs pour Liquid Organic Hydrogen Carriers) présente une alternative très prometteuse. Ils permettent de stocker et de transporter efficacement l'hydrogène avec une faible densité énergétique et volumétrique. A cet égard, l'acide formique est reconnu comme l'un des transporteurs d'hydrogène les plus prometteurs. Dans le cadre de cette thèse, nous nous sommes principalement intéressés à la production photocatalytique de l’hydrogène à partir de l’acide formique sous lumière visible en utilisant des photocatalyseurs à base d’oxyde de Cuivre et de Fer. Ces photocatalyseurs ont montré une très bonne activité et sélectivité pour la déshydrogénation de l’acide formique sous lumière visible à température ambiante et sous flux continu. Les résultats obtenus dans cette thèse donnent non seulement un aperçu des facteurs affectant la réaction mais aussi des perspectives pour améliorer à la fois l’activité des photocatalyseurs et la sélectivité de la déshydrogénation. Par conséquent, les catalyseurs à base de cuivre, connus pour leur stabilité relativement faible dans les procédés en phase liquide, peuvent bien être considérés comme des photocatalyseurs très prometteurs spécifiquement en phase gazeuse/vapeur. Les connaissances fondamentales résultant de ce travail devraient peut avoir un impact significatif sur le développement durable et rentable de la production hautement sélective d'hydrogène à partir de l'acide formique dans des conditions douces
Technological development aimed at building society expending hydrogen as an energy source, with low environmental impact and high efficiency, is urgently needed. However, as hydrogen is flammable, safety issues linked to its storage and transport limit its use as a fuel. The use of liquid organic hydrogen carriers (LOHCs) presents a very promising alternative. They enable an efficient storage and transport of hydrogen at low energy and volumetric densities. In this respect, formic acid is recognized as one of the most promising LOHC. In this thesis, we focused on the photocatalytic production of hydrogen from formic acid, using copper-iron oxide photocatalysts. These photocatalysts showed very good activity and selectivity for the dehydrogenation of formic acid under visible light at room temperature and under continuous flow. The results obtained in this thesis not only provide insight into the factors affecting the reaction, but also offer prospects for improving both photocatalyst activity and dehydrogenation selectivity. As a result, copper-based catalysts, known for their relatively low stability in liquid-phase processes, may well be considered highly promising photocatalysts specifically in the gas/vapor phase. The fundamental insights resulting from this work should have a significant impact on the sustainable and cost-effective development of highly selective hydrogen production from formic acid under mild conditions

>Magister Scientiae - MSc
Spinel lithium manganese oxide (LiMn2O4), for its low cost, easy preparation and nontoxicity, is regarded as a promising cathode material for lithium-ion batteries. However, a key problem prohibiting it from large scale commercialization is its severe capacity fading during cycling. The improvement of electrochemical cycling stability is greatly attributed to the suppression of Jahn-Teller distortion (Robertson et al., 1997) at the surface of the spinel LiMn2O4 particles. These side reactions result in Mn2+ dissolution mainly at the surface of the cathode during cycling, therefore surface modification of the cathode is deemed an effective way to reduce side reactions. The utilization of a nanocomposite which comprises of metallic Cu and Au were of interest because their oxidation gives rise to a variety of catalytically active configurations which advances the electrochemical property of Li-ion battery. In this research study, an experimental strategy based on doping the LiMn2O4 with small amounts of Cu-Au nanocomposite cations for substituting the Mn3+ ions, responsible for disproportionation, was employed in order to increase conductivity, improve structural stability and cycle life during successive charge and discharge cycles. The spinel cathode material was synthesized by coprecipitation method from a reaction of lithium hydroxide and manganese acetate using 1:2 ratio. The Cu-Au nanocomposite was synthesized via a chemical reduction method using copper acetate and gold acetate in a 1:3 ratio. Powder samples of LiMxMn2O4 (M = Cu-Au nanocomposite) was prepared from a mixture of stoichiometric amounts of Cu-Au nanocomposite and LiMn2O4 precursor. The novel LiMxMn2O4 material has a larger surface area which increases the Li+ diffusion coefficient and reduces the volumetric changes and lattice stresses caused by repeated Li+ insertion and expulsion. Structural and morphological sample analysis revealed that the modified cathode material have good crystallinity and well dispersed particles. These results corroborated the electrochemical behaviour of LiMxMn2O4 examined by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The diffusion coefficients for LiMn2O4 and LiMxMn2-xO4 obtained are 1.90 x10-3 cm2 / s and 6.09 x10-3 cm2 / s respectively which proved that the Cu-Au nanocomposite with energy band gap of 2.28 eV, effectively improved the electrochemical property. The charge / discharge value obtained from integrating the area under the curve of the oxidation peak and reduction peak for LiMxMn2-xO4 was 263.16 and 153.61 mAh / g compared to 239.16 mAh / g and 120 mAh / g for LiMn2O4. It is demonstrated that the presence of Cu-Au nanocomposite reduced side reactions and effectively improved the electrochemical performance of LiMn2O4.

A sediment toxicity test using the freshwater oligochaetes Lumbriculus variegatus and Tubifex tubifex was performed. We evaluated acute and chronic toxicity affects of copper and cadmium on reproduction in both species and the bioaccumulation of both metals by L. variegatus using artificial sediment. L. variegatus bioconcentrated copper 22‐fold and cadmium 16‐fold after a 14‐day exposure to spiked artificial sediments with 0.02% organic content. The EC50 for T. tubifex varied depending upon endpoint from 2.7 to 2.8 mg/L for cadmium and from 8.4 to 8.9 mg/L for copper. The EC50 for L. variegatus was 2.2 mg/L for cadmium and 3.9 mg/L for copper. Based on these results, L. variegatus appears to be more sensitive to metal toxicity in artificial sediments than T. tubifex.

Роботу виконано на кафедрі конструювання верстатів, інструментів та машин Тернопільського національного технічного університету імені Івана Пулюя Міністерства освіти і науки України
В дипломній роботі здійснено розрахунок та конструювання основних виконавчих вузлів спеціального токарно-копіювального напівавтомата, моделювання динамічних характеристик шпиндельного вузла.
In the thesis the calculation and design of the main executive units of a special turning-copier semiautomatic lathe, modeling of dynamic characteristics of the spindle node is carried out.
Вступ; Перший розділ "загальний розділ "; Другий розділ "Оптимізація схеми формоутворення на проектованому верстаті"; Третій розділ "Оптимізація компоновочної схеми проектованого верстата" ; Четвертий розділ "Вибір та обґрунтування вихідних даних на розробку проектуверстатного обладнання"; П’ятий розділ "Проектування конструкції верстатного обладнання (науково-дослідна частина)"; Шостий розділ "Обґрунтування економічної ефектив-ності"; Сьомий розділ "Охорона праці та безпека в надзвичайних ситуаціях"; Восьмий розділ "Екологія" ; Дев’ятий розділ «спеціальний розділ. САПР» ; Висновки

Fundação de Amparo à Pesquisa do Estado do Rio de Janeiro
Os óxidos de enxofre (SOx) são um dos maiores poluentes atmosféricos e um dos precursores da chuva ácida. Um levantamento feito na Petrobrás mostrou que cerca de 17% dos SOx emitidos numa refinaria são oriundos do processo de FCC. Com o avanço dos controles ambientais, traduzido numa legislação mais restritiva, a técnica de incorporação de aditivos para remoção de SOx em UFCCs apresenta-se como a alternativa de menor custo frente outras tecnologias de abate das emissões de SOx. No presente trabalho, foram estudados aditivos constituídos por compostos derivados de hidrotalcitas com a substituição parcial do magnésio e do alumínio por cobre e/ou manganês, sendo estes impregnados ou não por dióxido de cério. Estes aditivos foram submetidos a testes de desempenho em uma unidade multi-propósito acoplada a um micro-GC/TCD. Em todos os testes, a corrente gasosa para a etapa de adsorção oxidativa foi de 1700 ppm de SO2 e 1,5% O2 em He e, para a etapa de regeneração, 30% H2/He. No primeiro conjunto de testes, realizou-se uma adsorção a 720C de 10 min e regeneração com um patamar a 530C, seguido de um TPR até 800C. Observou-se que as amostras impregnadas com cério apresentaram o melhor desempenho na remoção de SO2, indicando que o cério pode ter um papel de promotor da oxidação de SO2 a SO3. Os resultados do TPR mostram que as amostras com cério e com manganês parecem apresentar menores temperaturas de redução dos sulfatos, apesar das maiores liberações de H2S serem identificadas nas amostras com cobre. No segundo conjunto de testes, a adsorção foi a 720C durante 35 min e a regeneração a 650C por 5 minutos em um patamar de 5 minutos, seguida de um TPR até 800C. Para os tempos de sulfatação curtos (5 e 10 min), os resultados confirmaram o efeito positivo que a incorporação de CeO2 apresenta sobre a adsorção oxidativa do SO2. Todavia, para tempos de reação maiores (35 min), não se observou uma correlação clara entre a composição química do catalisador e a quantidade total de SOx removida. Os aditivos foram ainda testados em ciclos de reação-regeneração em condições equivalentes ao segundo conjunto de testes descrito. De um modo geral, os aditivos que contêm cobre têm uma vida útil superior aos demais, possivelmente, pelo fato do cobre ter importante papel na regeneração do aditivo
The sulfur dioxide emissions are one of the most atmospheric pollutant and precursor of acid rain. A survey carried out by Petrobras shows that around 17% of the SOx emissions of its refineries derive from the FCC process. In recent years, the strengthening of environmental controls with more restrictive legislation turns the incorporation of additives for SOx removal into a low-cost alternative technique compared with other technologies of SOx abatement. The purpose of this work is to study additives composed by derivated hydrotalcite compounds with partial substitution of magnesium and aluminium for copper and/or manganese, and with or without dioxide cerium impregnation. The performance of these additives has been tested in a multi-proposal unit coupled with a micro-GC/TCD. In all the tests it was used a gas stream of 1700 ppm of SO2 and 1,5% O2 in He for the oxidative adsorption step and for the regeneration step a 30% H2 in He stream. In the first test, it was carried out an adsoprtion step at 720C for 10 minutes and a regeneration step at a 530C level, flollowed by an TPR until 800C. The cerium dioxide impregnated samples showed a better result for SO2 removal, which implies cerium may play a role as catalyst for SO2 to SO3 oxidation. The TPR results show cerium and manganese may diminish the temperature of sulfates reduction, besides copper samples releases more H2S gases. In the second test, the adsorption step was carry out at 720C for 35 minutes and the regeneration step at 650C for 5 minutes folloewd by a TPR until 800C. In short times reaction (5 or 10 min) the results confirm the positive effect of cerium in the SO2 oxidantion adsorption. However, for longer time reaction (35 min), it cant be observed a relationship between chemical composition of the aditive and the total amount of SOx removed. Additives were still tested in reaction-regeneration cycles in the same conditions of the second test described above. In general, the additives without copper in their composition has a life time minor than that with copper; possibly, because copper plays an important role in the additive regeneration

Nature develops several materials with remarkable functional properties composed of comparatively simple base substances. Biological materials are often composites, which optime the conformation to their function. On the other hand, synthetic materials are designed a priori, structuring them according to the performance to be achieved. 3D printing manufacturing is the most direct method for specific component production and earmarks the sample with material and geometry designed ad-hoc for a defined purpose, starting from a biomimetic approach to functional structures. The technique has the advantage of being quick, accurate, and with a limited waste of materials. The sample printing occurs through the deposition of material layer by layer. Furthermore, the material is often a composite, which matches the characteristics of components with different geometry and properties, achieving better mechanical and physical performances. This thesis analyses the mechanics of natural and custom-made composites: the spider body and the manufacturing of metallic and non-metallic graphene composites. The spider body is investigated in different sections of the exoskeleton and specifically the fangs. The study involves the mechanical characterization of the single components by the nanoindentation technique, with a special focus on the hardness and Young's modulus. The experimental results were mapped, purposing to present an accurate comparison of the mechanical properties of the spider body. The different stiffness of components is due to the tuning of the same basic material (the cuticle, i.e. mainly composed of chitin) for achieving different mechanical functions, which have improved the animal adaptation to specific evolutive requirements. The synthetic composites, suitable for 3D printing fabrication, are metallic and non-metallic matrices combined with carbon-based fillers. Non-metallic graphene composites are multiscale compounds. Specifically, the material is a blend of acrylonitrile-butadiene-styrene (ABS) matrix and different percentages of micro-carbon fibers (MCF). In the second step, nanoscale filler of carbon nanotubes (CNT) or graphene nanoplatelets (GNP) are added to the base mixture. The production process of composite materials followed a specific protocol for the optimal procedure and the machine parameters, as also foreseen in the literature. This method allowed the control over the percentages of the different materials to be adopted and ensured a homogeneous distribution of fillers in the plastic matrix. Multiscale compounds provide the basic materials for the extrusion of fused filaments, suitable for 3D printing of the samples. The composites were tested in the configuration of compression moulded sheets, as reference tests, and also in the corresponding 3D printed specimens. The addition of the micro-filler inside the ABS matrix caused a notable increment in stiffness and a slight increase in strength, with a significant reduction in deformation at the break. Concurrently, the addition of nanofillers was very effective in improving electrical conductivity compared to pure ABS and micro-composites, even at the lowest filler content. Composites with GNP as a nano-filler had a good impact on the stiffness of the materials, while the electrical conductivity of the composites is favoured by the presence of CNTs. Moreover, the extrusion of the filament and the print of fused filament fabrication led to the creation of voids within the structure, causing a significant loss of mechanical properties and a slight improvement in the electrical conductivity of the multiscale moulded composites. The final aim of this work is the identification of 3D-printed multiscale composites capable of the best matching of mechanical and electrical properties among the different compounds proposed. Since structures with metallic matrix and high mechanical performances are suitable for aerospace and automotive industry applications, metallic graphene composites are studied in the additive manufacturing sector. A comprehensive study of the mechanical and electrical properties of an innovative copper-graphene oxide composite (Cu-GO) was developed in collaboration with Fondazione E. Amaldi, in Rome. An extensive survey campaign on the working conditions was developed, leading to the definition of an optimal protocol of printing parameters for obtaining the samples with the highest density. The composite powders were prepared following two different routes to disperse the nanofiller into Cu matrix and, afterward, were processed by selective laser melting (SLM) technique. Analyses of the morphology, macroscopic and microscopic structure, and degree of oxidation of the printed samples were performed. Samples prepared followed the mechanical mixing procedure showed a better response to the 3D printing process in all tests. The mechanical characterization has instead provided a clear increase in the resistance of the material prepared with the ultrasonicated bath method, despite the greater porosity of specimens. The interesting comparison obtained between samples from different routes highlights the influence of powder preparation and working conditions on the printing results. We hope that the research could be useful to investigate in detail the potential applications suitable for composites in different technological fields and stimulate further comparative analysis.

碩士
國立臺灣科技大學
電子工程系
105
Cobalt oxide and copper-cobalt oxide thin films have been successfully deposited by reactive ion beam sputter deposition utilizing an anode layer ion source sputtering module. Samples were deposited at 150 and 300℃ at various oxygen flow rates on both Si and quartz substrates. Experimental results show that samples deposited at 150℃ are all amorphous, while both cobalt and copper-cobalt oxide deposited at 300℃ exhibit a spinel structure. Increasing oxygen partial flow rates results in deteriorated crystalline quality and reduced resistivity, while the introduction of copper also results in deteriorated crystalline quality and reduced resistivity. Transmission spectra indicate that copper results in the formation of inter-band defect states. Photoelectrochemical measurements show that both cobalt and copper-cobalt oxide are of p-type, while copper-cobalt oxide shows the highest photocurrent density. This improved photocurrent density is attributed due to the presence of inter-band states that results in improved absorption of photons.

Metallic interconnects in intermediate temperature solid oxide fuel cells (IT-SOFC) stacks form Cr2O3 scales on their surface. Such oxide scales can be further oxidized to Cr6+ containing gaseous species that migrate and deposit at the cathode triple phase boundaries, causing significant degradation in the performance of the SOFCs. This phenomenon is termed as ‘Cr-poisoning’. A solution to this problem is the application of coatings on the interconnects that act as a diffusion barrier to Cr migration. Two different Cu/Mn spinel compositions, Cu1.3Mn1.7O4 and CuMn1.8O4, were studied as coating materials. Dense coatings were deposited on both flat plates and meshes by electrophoretic deposition (EPD) followed by subsequent thermo-mechanical or thermal densification steps. At room temperature, Cu1.3Mn1.7O4 coatings were found to have a mixture of CuO and spinel phases, while CuMn1.8O4 coatings were found to have a mixture of Mn3O4 and spinel phases. However, CuMn1.8O4 is a pure spinel phase between 750 °C and 850 °C. After densification processing and high temperature oxidation, a Cr2O3 layer was formed at the coating/alloy interface, which partially reacted with the spinel coatings to form a dense cubic spinel layer of the general composition (Cu,Mn,Cr)3-xO4. In addition, Cr-rich precipitates, formed in the dense layer close to coating/alloy interface. It is believed that these are Cr2O3 precipitates, formed when the solubility of Cr in the spinel phase is reached. Solubility experiments using powders showed that 1 mole of CuMn1.8O4 can effectively getter 1.83 moles of Cr2O3 at 800°C. Electrical conductivity of (Cu,Mn,Cr)3-xO4 was found to be at least two orders of magnitude higher than that of Cr2O3. The coatings acted as an effective Cr getter whose lifetime depends on the oxidation temperature, coating thickness, and the overall porosity in the coating. In-cell electrochemical testing showed that the CuMn1.8O4 coatings on Crofer 22 APU meshes performed significantly better than commercial Cu/Mn spinel coatings. The CuMn1.8O4 coatings gettered Cr effectively for 12 days at 800 ºC, leading to no performance loss of the cell due to Cr-poisoning. Significantly longer lifetime can be achieved at 750 ºC or lower, which is the target operational temperature regime of IT-SOFCs.

Solid oxide fuel cells (SOFCs) have gained renewed interest due to their high energy-conversion efficiency, new discovery of fossil fuel sources, and low greenhouse gas emission. However, performance degradation during long-term operation is one of the greatest challenges to overcome for commercialization of SOFCs. At intermediate temperatures, chromium (Cr) vapor species that form over chromia-forming alloy interconnect, can transport and deposit in the cathode, and poison the cathode performance. Although extensive studies have been conducted on the Cr-poisoning phenomena, the mechanism of cathode performance degradation still needs to be clarified. Therefore, there is an urgent need to understand the degradation mechanisms and develop corresponding mitigation strategies. In this research, anode-supported cells with (La,Sr)MnO3-based cathode were fabricated. The cells were electrochemically tested with and without the presence of chromia-forming alloy interconnect, and operating conditions including cathode atmosphere, current condition, and interconnect contact were varied independently. It was found that both humidity and cathodic current promote chromium poisoning. Microstructural characterizations also confirmed that larger amounts of chromium-containing deposits are present at the cathode/electrolyte interfaces of the cell tested with cathodic current and/or humidity. With the help of free energy minimization calculations, the equilibrium cell potentials for Cr vapor species reductions are estimated and found to be very close to the open-circuit potential of the cell. Combining the experimental and computational results, the roles of humidity and cathodic current in Cr-poisoning are evaluated, and a mechanism associated to Cr vapor species dissociation at the triple-phase-boundaries is proposed. To evaluate the Cr-poisoning effects on cell performance, an analytical polarization model is used for quantitatively separating the contribution of various cell polarizations. By curve-fitting the current-voltage traces to this model, the changes of cathode polarizations due to Cr-poisoning are quantified. Under normal operating conditions, the cathodic activation polarization is determined to be most negatively impacted by Cr-poisoning. Mitigation of the Cr-poisoning effects using a dense lab-developed CuMn1.8O4 spinel interconnect coating was demonstrated. Employing the spinel coated interconnect mesh in on-cell tests, it was found that both the degradation in cell performance and Cr deposition in the cathode are significantly mitigated.

Σκοπός της παρούσας διδακτορικής διατριβής ήταν η ανάπτυξη ενός αποτελεσματικού καταλυτικού συστήματος με βάση το χαλκό, για την αναμόρφωση της μεθανόλης. Για το σκοπό αυτό εξετάστηκαν οι καταλυτικές ιδιότητες τριών συστημάτων βασιζόμενων σε καταλύτες χαλκού και παρασκευασμένων με τη μη συμβατική μέθοδο της καύσης: CuO-CeO2, τροποποιημένων καταλυτών CuO-CeO2 και Cu-Mn-O για την προαναφερθείσα διεργασία, καθώς και τα βέλτιστα δείγματα των καταλυτών CuO-CeO2 και Cu-Mn-O υποστηριγμένων σε μεταλλικούς αφρούς Al. Τα φυσικοχημικά χαρακτηριστικά των καταλυτών CuO-CeO2, βρέθηκαν να εξαρτώνται από τις παραμέτρους σύνθεσης. Ο βέλτιστος καταλύτης παρασκευάστηκε με λόγο Cu/(Cu+Ce)= 0.15. Στους τροποποιημένους καταλύτες CuO-CeO2, ένα μέρος του τροποποιητή εισχωρεί στο πλέγμα της δημήτριας, οδηγώντας στο σχηματισμό στερεού διαλύματος. Αυτό είχε ως αποτέλεσμα να επηρεαστούν τα φυσικοχημικά χαρακτηριστικά των δειγμάτων, αλλά και η καταλυτική συμπεριφορά τους. Οι σπινελικοί καταλύτες Cu-Mn-O είναι πολύ ενεργοί παρά τη μικρή ειδική επιφάνειά τους. Η ενεργότητά τους είναι συγκρίσιμη με αυτή των εμπορικών καταλυτών Cu-Zn-Al. Ο βέλτιστος καταλύτης ήταν αυτός με λόγο Cu/(Cu+Mn)= 0.30. Εξίσου αποδοτικοί για την παραγωγή υδρογόνου μέσω αναμόρφωσης της μεθανόλης, μονολιθικοί καταλύτες Cu-Ce/Al foam και Cu-Mn/Al foam παρασκευάστηκαν με τη μέθοδο της καύσης. Με βάση τα ευρήματα της ισοτοπικής μελέτης, προτείνεται για τον καταλύτη Cu-Mn-O ότι η αναμόρφωση πραγματοποιείται αποκλειστικά μέσω μηχανισμού που περιλαμβάνει τον ενδιάμεσο σχηματισμό μυρμηκικού μεθυλεστέρα. Για τους καταλύτες Cu-Ce-O και Cu-Zn-Al πραγματοποιείται ταυτόχρονα και μηχανισμός που περιλαμβάνει ως ενδιάμεσο είδος το διοξομεθυλένιο.
The scope of the present thesis was the development of an effective catalytic copper-based system for methanol reforming. The catalytic properties of three different copper-based systems prepared via the non conventional combustion method, were investigated for the aforementioned process: CuO-CeO2, modified CuO-CeO2 and Cu-Mn-O, as well as the optimal CuO-CeO2 and Cu-Mn-O oxide cata¬lysts supported on Al metal foam. The physicochemical characteristics of CuO-CeO2 catalysts were found to be influenced by the parameters of the synthesis. The optimal catalyst was prepared with Cu/(Cu+Ce) ratio equal to 0.15. In the case of modified CuO-CeO2 catalysts, at least part of dopant cations gets incorporated into the CeO2 lattice leading to solid solution formation. As a result, the physicochemical characteris¬tics of the samples were influenced, as well as their catalytic performance. Cu-Mn spinel oxide catalysts were found to be highly active despite their low surface area. Their activity is comparable to that of commercial Cu-Zn-Al catalysts. The optimal catalyst was prepared with a Cu/(Cu+Mn) ratio equal to 0.30. Structured Cu-Ce/Al foam and Cu-Mn/Al foam catalysts prepared via in situ combustion method were equally effective for hydrogen production via methanol reforming. Based on the findings of an isotopic study, a mechanism has been proposed for the reforming reaction over Cu-Mn-O, where methyl formate is formed as a reaction intermediate. An additional reaction mechanism is taking place over Cu-Ce-O and commercial Cu/ZnO/Al2O3 catalysts, resulting in the intermediate dioxomethylene.

Due serie di catalizzatori a base di ossidi misti con composizione nominale M13-xM2xO4 sono stati sintetizzati con metalli non nobili, in cui M1=Co e M2=Fe o M1=Cu e M2=Mn, con il metodo della co-precipitazione. Ogni serie è composta da 5 catalizzatori con rapporti tra i cationi pari a M2/(M1+M2) 0.00, 0.33, 0.50, 0.67, 1.00. I catalizzatori sono stati caratterizzati attraverso tecniche XRD, EDX, fisisorbimento di N2, FT-IR, UV-VIS, TEM e TPR, e successivamente testati nelle reazioni di ossidazione del 5-idrossimetilfurfurale (HMF) derivante da biomasse a diversi intermedi ad elevato valore aggiunto, che hanno importanti applicazioni in vari settori dell’industria chimica, tra cui l'anidride maleica (MA), la 2,5-furandicarboxaldeide (DFF), l'acido 5-idrossimetil-2-furancarbossilico (HMFCA), e l’acido 5-formil-2-furancarbossilico (FFCA) e l’acido 2,5-furandicarbossilico (FDCA), che è importante come un sostituto alternativo all’acido tereftalico derivato da materie prime fossili per la produzione di polietilenetereftalato (PET). I prodotti di reazione derivanti dall’ossidazione del HMF sono stati analizzati mediante HPLC ed è stato eseguito un approfondito studio cinetico. L'obiettivo finale è stato non solo quello di trovare una correlazione tra proprietà fisico-chimiche ed attività catalitica dei catalizzatori presi in esame per la complessa trasformazione dell’HMF a FDCA, ma anche quello di dare un contributo consistente ai processi chimici industriali alla base di uno sviluppo sostenibile della società.
Two series of mixed oxide catalysts with nominal composition M13-xM2xO4 have been synthesized with non-noble metals, wherein M1=Co and M2=Fe or M1=Cu and M2=Mn, by cost effective co-precipitation method. Each serie consists of 5 catalysts with the cation fractions M2/(M1+M2) of 0.00, 0.33, 0.50, 0.67, 1.00. The catalysts have been characterised using XRD, EDX, N2 physisorption, FT-IR, UV-VIS, TEM and TPR techniques, then employed in the successive oxidation reactions of biomass derived 5-hydroxymethylfurfural (HMF) to several value added chemicals, which have a diverse portfolio of applications in various industries, including maleic anhydride (MA), 2,5-furandicarboxaldehyde (DFF), 5-Hydroxymethyl-2-furancarboxylic acid (HMFCA), 5-formyl-2-furancarboxylic acid (FFCA) and 2,5-furandicarboxylic acid (FDCA), which can serve as an alternative substitute for fossil fuel derived terephthalic acid in the production of polyethylene terephthalate (PET) plastics. The oxidation reaction products of HMF were analyzed by HPLC then kinetics study has been performed. The ultimate goal is not only to investigate the correlations between physicochemical properties and catalytic performances of the aformentioned catalysts on the complex cascade HMF to FDCA oxidation process but also to make a humble contribution to the scientific literature for a sustainable, renewable and greener world.
On a synthétisé deux séries de catalyseurs d'oxydes mixtes de composition nominale M13-xM2xO4 avec des métaux non nobles, dans laquelle M1=Co et M2=Fe ou M1=Cu et M2=Mn, par un procédé de co-précipitation rentable. Chaque série se compose de 5 catalyseurs avec les fractions cationiques M2/(M1+M2) de 0,00, 0,33, 0,50, 0,67, 1,00. Les catalyseurs ont été caractérisés en utilisant les techniques de XRD, EDX, physisorption de N2, FT-IR, UV-VIS, TEM et TPR, puis utilisés dans les réactions d'oxydation successives de la 5-hydroxyméthylfurfural dérivée de la biomasse (HMF) vers plusieurs produits chimiques à valeur ajoutée qui ont Un large éventail d'applications dans diverses industries. Ces produits comprennent l'anhydride maléique (MA), le 2,5-furandicarboxaldéhyde (DFF), l'acide 5-hydroxyméthyl-2-furancarboxylique (HMFCA), l'acide 5 formyl-2 furancarboxylique (FFCA) , L'acide 5-furandicarboxylique (FDCA), qui peut servir de substitut alternatif à l'acide téréphtalique dérivé du combustible fossile dans la production de plastiques de poly (éthylène téréphtalate) (PET). Les produits de réaction d'oxydation de HMF ont été analysés par CLHP puis une étude cinétique a été réalisée. Le but ultime est non seulement d'étudier les corrélations entre les propriétés physico-chimiques et les performances catalytiques des catalyseurs mentionnés sur le processus d'oxydation en cascade complexe de HMF à FDCA, mais aussi d'apporter une contribution modeste à la littérature scientifique pour un monde durable, renouvelable et plus vert.