Dissertations / Theses on the topic 'Solid Catalysts'
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Fakiha, Samir Amin A. "Preparation and properties of solid catalysts." Thesis, Queen's University Belfast, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.335497.
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PERRA, DANIO. "Solid acid catalysts for biorefinery processes." Doctoral thesis, Università degli Studi di Cagliari, 2016. http://hdl.handle.net/11584/266767.
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The present work regards the study of alternative synthetic routes for biofuels and biochemicals. Biofuels and biochemicals constitute the two main classes of biorefinery products. Biofuels are obtained from biomass and have many environmental advantages over the traditional fuels. In this work particular attention has been given to biodiesel, one of the most widely used biofuels. Biodiesel is a safe, non-toxic, and biodegradable alternative diesel fuel. The development of active acid catalysts for biodiesel synthesis could reduce the production costs, in particular because the acid catalysts permit the use of low value feedstocks such as waste and non-edible oils. Biodiesel production occurs with co-production of glycerol, which is co-product also in other industrial productions such as the production of fatty acids and soaps. Because of its large production the market demand is largely less than the supply. For this reason glycerol is considered a problematic product. Possible solution to its disposal is the use as platform chemical in the production of high value bioproducts. Among them are particularly interesting the trioses dihydroxyacetone and glyceraldehyde. They could be feedstocks for an alternative synthetic way for lactic acid and its esters. Lactic acid and lactates are, nowadays, considerably important because they are used as building blocks in the production of biodegradable polymers (the polylactic acids), which are potential substitute for petroleum derived polymers. Lactic acid is also one of the most promising bio-based platform molecules. The high costs of the conventional production process hinder the use of lactic acid and lactates in many applications. So it is essential to develop cheaper and greener synthetic routes.
In this work catalysts synthesis, characterization of the materials, and catalytic testing have been carried out mainly at the Laboratory of Industrial Chemistry in the Department of Chemical and Geological Sciences of the University of Cagliari.
The study involved the use of several techniques for the characterization of the materials. All the catalytic results have been related to the acid properties of the tested materials. For this reason the measurements of adsorption microcalorimetry and adsorption FTIR using basic probe molecules have been the most important used techniques in this work.
The measurements of adsorption microcalorimetry were carried out at the Laboratory of Industrial Chemistry in Cagliari while the measurements of adsorption FTIR were carried out under the supervision of Prof. Konstantin Hadjiivanov at the Institute of General and Inorganic Chemistry of the Bulgarian Academy of Sciences.
This work is divided in five chapters. The first chapter is an introduction of the fundamentals of sustainable chemistry, biorefinery and acid-base heterogeneous catalysis. The
second chapter is a description of the most important techniques for the characterization of acid-base properties of solid materials. In the third chapter are listed the used materials, the experimental procedures and apparatus. The chapter four is the study of the acid catalyzed transesterification of tryglicerides for the production of biodiesel and glycerol. In chapter five is described the work on the conversion of dihydroxyacetone to methyl lactate
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Yamamoto, Takashi. "Studies on the Catalysis by New Solid Acid Catalysts and the Characterization." Kyoto University, 1999. http://hdl.handle.net/2433/77922.
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Wang, Qiyan. "Design of solid micellar catalysts for sustainable chemistry." Electronic Thesis or Diss., Université de Lille (2018-2021), 2021. http://www.theses.fr/2021LILUR029.
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L'épuisement des ressources fossiles et les préoccupations environnementales croissantes encouragent la production de produits chimiques et de carburants durables à partir des ressources de la biomasse et du CO2. L'objectif fondamental de ce projet de recherche concerne la conception d'un nouveau système de catalyseur micellaire à un seul atome. Les catalyseurs sont classiquement classés en homogènes et hétérogènes. Les catalyseurs homogènes offrent une efficacité élevée, liée à une utilisation maximale des métaux et des sites actifs hautement accessibles, et une sélectivité élevée, en raison de la structure similaire du site actif. Cependant, les catalyseurs homogènes souffrent souvent d'une faible stabilité et d'une mauvaise recyclabilité. Au contraire, les catalyseurs hétérogènes présentent une stabilité et une recyclabilité excellentes, mais leur utilisation et sélectivités en métal actif sont généralement faibles. Les catalyseurs mono-atomes (SAC) sont une famille émergente de matériaux qui combinent les meilleurs avantages des catalyseurs homogènes et hétérogènes. Les SAC affichent une utilisation atomique d'environ 100%, une stabilité relativement élevée et une séparation facile du milieu réactionnel. Cependant, il existe plusieurs inconvénients associés à l'utilisation / la synthèse de catalyseurs à un seul atome: la plupart des procédures de synthèse pour les SAC nécessitent l'utilisation de ligands jetables coûteux et d'équipements et de techniques hautement spécialisés qui entravent leur production et leur applicabilité à grande échelle. Un SAC micellaire solide a été développé dans le cadre de ce projet par l'incorporation d'atomes métalliques dans les parois du MCM-41, stabilisé par un tensioactif cétyltriméthylammonium (CTA +). Le procédé est très simple et peu coûteux à synthétiser car il ne nécessite pas l'ajout de ligands coûteux ou de techniques d'atmosphère inerteThe depletion of fossil resources and increasing environmental concerns encourage the production of sustainable chemicals and fuels from biomass resources and CO2. The fundamental target of this research project deals with the design of a novel single atom micellar catalyst system. Catalysts are conventionally classified into homogeneous and heterogeneous. Homogeneous catalysts offer high efficiency, related to maximal metal utilization and highly accessible active sites, and high selectivity, due to the similar active site's structure. However, homogeneous catalysts often suffer from low stability and poor recyclability. On the contrary, heterogeneous catalysts exhibit excellent stability and recyclability, yet their active metal utilization and selectivities are typically low. Single-atom catalysts (SACs) are an emerging family of materials that combine the best advantages of homogeneous and heterogeneous catalysts. SACs display approximately 100% atomic utilization, relatively high stability, and easy separation from the reaction media. However, there are several drawbacks associated with the use/synthesis of single-atom catalysts: most synthetic procedures for SACs require the use of expensive throw-away ligands and highly specialized equipment and techniques that hinder their scale-up production and applicability. A solid micellar SAC has been developed in the framework of this project by the incorporation of metal atoms into the walls of MCM-41, stabilized by a Cetyltrimethylammonium (CTA+) surfactant. The method is very simple and cheap to synthesize since it does not require the addition of expensive ligands or inert atmosphere techniques
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Li, Zhijian. "Novel solid base catalysts for Michael additions." Doctoral thesis, [S.l.] : [s.n.], 2005. http://deposit.ddb.de/cgi-bin/dokserv?idn=976576759.
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Hart, Mark Peter. "Solid acid catalysts for liquid phase reactions." Thesis, University of Huddersfield, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.270434.
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Schimming, Sarah McNew. "Design of solid catalysts for biomass upgrading." Diss., Georgia Institute of Technology, 2014. http://hdl.handle.net/1853/54265.
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The two main requirements for ceria-zirconia hydrodeoxygenation (HDO) catalysts are the presence of defect sites to bind oxygenates and the ability to adsorb and dissociate hydrogen. Two types of sites were identified for exchange of hydrogen and deuterium. The activation energy for one type of site was associated with H2-D2 exchange through oxygen defect sites. The activation energy for the second type of site was associated with H2-D2 exchange through hydroxyl groups and correlated with crystallite size. Ceria-zirconia can convert guaiacol, a model pyrolysis oil compound, with a high selectivity to phenol, an HDO product. Ceria-zirconia catalysts had a higher conversion of guaiacol to deoxygenated products as well as a higher selectivity towards phenol than pure ceria. They did not deactivate over the course of 72 hours on stream, whereas coking or the presence of water in the feed can cause serious decay of common HDO catalysts HDO. Therefore, ceria-zirconia catalysts are promising HDO catalysts for the first step of deoxygenation.
The stability of supported Ru on ZrO2 in acidic or basic environments at reaction temperature is examined. In this study, the ruthenium dispersion is greatly increased by hydrothermal treatment in acidic and basic pH without alterations to the surface area, pore volume, pore size or crystal structure. An increase in Ru dispersion showed an increase in the selectivity to propylene glycol relative to ethylene glycol. A decrease in total Lewis acid site concentration was correlated with a decrease in the ethylene glycol yield. The conclusions of this study indicate that stability of catalysts in realistic industrial environments is crucial to the design of catalysts for a reaction.
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Mordacque, Olivier Michel André. "Selective alkylation of phenols using solid catalysts." Thesis, University of York, 2003. http://etheses.whiterose.ac.uk/14186/.
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Alkylphenols are important industrial chemicals used in a wide range of applications. In particular, 2,6-ditertbutylphenol is an indispensable building block for anti-oxidants and light protective agents. A new solid catalyst was prepared, characterised and tested for the alkylation of phenols with alkenes in an attempt to reduce the environmental hazards associated with the aqueous wastes generated by the homogeneously catalysed alkylation reactions. The new silica gel supported aluminium phenolate catalyst was prepared by a two steps procedure, first grafting of an aluminium precursor such as aluminium trichloride or triethyl aluminium onto silica mainly through reaction with the support silanol groups, then exchange of the aluminium ligand with phenol. Catalysts exhibited mainly Lewis acidity and two types of active sites were detected. The new catalyst was successfully applied in the phenol - isobutene alkylation system. Catalysts exhibited an ortho- selectivity for the introduction of the first tertbutyl group. The selectivity of the second alkylation could be tuned by varying reaction conditions (reaction temperature, catalyst amount, alkene addition methods) and catalyst characteristics (support surface pre-treatment temperature, aluminium precursor and loading). Hence high yields of 2,4-ditertbutylphenol or moderated yields of 2,6-ditertbutylphenol were obtained. Alkylation of phenol with other alkenes and cresols alkylations were successfully catalysed by the new silica gel supported aluminium phenolate catalyst with the same selectivity. However, the diorthopropylphenol was the main dialkyl products when using propene as alkylating agent. "Greening" of the catalyst preparation by reducing the amount of solvent used was carried out without changing the selectivity and the activity of the catalyst. Reusability of the catalyst was investigated and a decrease of activity was observed. Storage of the catalyst was possible for a long time but activity and selectivity were affected.
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Cholerton, Mary. "Dehydration of alcohols using solid acid catalysts." Thesis, University of Southampton, 2014. https://eprints.soton.ac.uk/362638/.
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Solid acid catalysts were prepared through silicon substitution into aluminophosphate frameworks. Silicon incorporation was confirmed using solid state nuclear magnetic resonance spectroscopy. The nature of the acid sites generated was determined using Fourier Transform infrared spectroscopy. These materials were tested as catalysts for the dehydration of ethanol to ethylene at low operating temperatures. The materials were active for dehydration of ethanol to ethylene with significant differences observed between aluminophosphate frameworks both in terms of selectivity to the desired product but also in terms of the nature of the silicon substitution and the active sites. Links have been made between these properties and the observed catalytic behaviour. The effect of the catalytic framework is further explored though the testing of cobalt substituted aluminophosphates for ethanol dehydration. Silicon substituted aluminophosphates have been tested for the dehydration of 1-phenylethanol to styrene as an example of catalysis in the liquid phase. Here the influence of framework was particularly significant due to the large substrate. The effect of redox metals in the aluminophosphate framework has been investigated through the use of calcined and pre-reduced cobalt substituted aluminophosphates for the dehydration of ethanol to ethylene. Analysis of the catalytic product stream was combined with UV-Visible measurements to investigate potential redox processes occurring during the reaction time on stream and the influence of the oxidation state of the redox metal on the catalytic products of the reaction.
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Rennison, A. J. "CO hydrogenation on reduced solid solution catalysts." Thesis, University of Bath, 1987. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.378000.
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Patil, Pratap Tukaram. "Nanoscopic metal fluoride based novel solid catalysts." Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät I, 2009. http://dx.doi.org/10.18452/16021.
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Metallfluoride sind dank ihrer hohen chemischen und thermischen Stabilität, insbesondere bei Reaktionen unter Beteiligung von hoch korrosiven Gasen (HF, HCl, Cl2, F2) den entsprechenden Oxiden überlegen. Über den Sol-Gel Prozess synthetisierte Produkte weisen oft spezifische, zum Teil sehr unterschiedliche Eigenschaften im Vergleich zu klassisch hergestellten Verbindungen auf. In dieser Arbeit wurde der Sol-Gel Prozess zur Herstellung von binären Fluoriden (AlF3, MgF2, CaF2, CuF2 und FeF3) genutzt und zum Teil weiter entwickelt sowie das Synthesepotential dieser Methode als Zugang für komplexe Fluoride (KMgF3, K3AlF6), für Metallfluorid-geträgerte „nano Edelmetall-Systeme (Pd/AlF3, Pt/AlF3, Pd/CaF2, Pd/MgF2) und für Gast–Wirt–Metallfluorid-Systeme (CuF2/AlF3, FeF3/AlF3) untersucht. Die Eigenschaften der als kompakte Materialien hergestellten Metallfluorid Systeme wurden mit Hilfe spektroskopischer Methoden untersucht und dabei insbesondere deren Oberflächeneigenschaften bestimmt. Die neuen Materialien wurden für die Nutzung akademisch und industriell bedeutsamer Katalysereaktionen evaluiert und mit klassischen Katalysatoren verglichen. Es konnte gezeigt werden, dass der Sol-Gel Prozess für Fluoride zu neuartigen Materialien mit außergewöhnlichen Eigenschaften führt. Insbesondere infolge der Synthese-bedingten Vergrößerung der spezifischen Oberflächen um einen bis zu 20-fachen Faktor im Vergleich zu klassisch hergestellten Fluoriden konnten auch eine Reihe von katalytisch interessanten Metallen (Pd, Pt) in die nanoskopischen Festkörperfluoride eingebracht werden. Die TEM Aufnahmen zeigen, dass z. B. 2-5 nm große Palladiumpartikel sehr homogen in ca. 80 nm große CaF2- bzw. 20 nm große AlF3-Matrices in nur einem einzigen Reaktionsschritt eingeführt werden können. Die neuen Materialien wurden in verschiedenen katalytischen Reaktionen getestet und zeigten sich in mehreren Fällen den „Standard Katalysatoren“ überlegen.Because of their high chemical and thermal stabilities, metal fluorides have found to be advantageous over metal oxides in such cases where reactions involving generation of corrosive acids like HCl and HF are concerned. The Sol-gel method is known for the synthesis of materials with considerably different properties to those prepared by classical routes. In this work, sol-gel route has been employed for the synthesis of binary fluorides (AlF3, MgF2, CaF2, CuF2 and FeF3), hydroxyfluorides [AlF3-x(OH)x, MgF2-x(OH)x] complex fluorides (KMgF3, K3AlF6), metal fluoride supported nanoscopic noble metals (Pd, Pt) and host-guest fluoride systems (CuF2/AlF3, FeF3/AlF3). Besides the successful synthesis of metal fluorides described above, the present thesis deals with investigation of their bulk and surface properties using various analytical and spectroscopic methods (XRD, BET, NH3-TPD FTIR-pyridine adsorption, XPS, microscopic studies) as well as with their catalytic properties for the reactions of academic and industrial interest. Metal fluorides prepared via sol-gel method have shown to possess extraordinary surface properties in terms of surface area, particle size, porosity, Lewis acidity and distortion in their structures as compared to those of classical methods like aqueous synthesis or impregnations. A homogeneous dispersion of Pd nanoparticles supported on high surface area metal fluoride prepared by this method was confirmed by XRD, XPS and TEM imaging. Catalytic properties of these materials have been investigated for dehydrofluorination of hydrofluorocarbons, isomerization of citronellal, hydrodehalogenation of chlorodifluoromethane, Suzuki cross coupling and oxidative fluorination of benzene.
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Abdoullah, Mohamad. "Supported transition metal oxides as solid base catalysts." Thesis, University of Huddersfield, 2016. http://eprints.hud.ac.uk/id/eprint/28325/.
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The initial objective of the work studied here was to investigate the effects of isomorphously-substituted transition metals in lattice sites in Layered Double Hydroxides (LDHs) in terms of basicity and catalytic activity in base-catalysed reactions and oxidation reactions. Experiments in which copper(II), nickel(II), cobalt(II), zinc(II) and iron(III) were substituted in the lattice of synthetic hydrotalcites showed that, on calcination, the resultant mixed oxides arising from hydrotalcites containing copper(II) exhibited the greatest enhancement of catalytic activity. Test reactions were the conversion of 4-methylpentan-2-ol to methylisobutylketone, the oxidation of benzyl alcohol and the Henry reaction between benzaldehyde and nitromethane. Results showed conclusively that copper(II) imparted base catalytic activity to the mixed metal oxides formed on calcination of the LDHs. This was confirmed through an extension to the study in which the copper(II) content in the LDHs was varied. It was shown that there is an optimum copper(II) loading, above which additional copper(II) is not effectively incorporated in the LDH lattice. Other supports for copper(II) as an oxide were investigated, on the basis that activity was linked to effective dispersion of copper(II) oxide. A series of copper(II) dispersions on zirconia, on silica and on magnesium oxide were prepared and tested. The zirconia-supported catalysts were the most active so work was concentrated on these. Two methods for preparing copper(II) oxide/zirconia were investigated, using a solid state reaction and using a sol-gel process. Catalysts were prepared with molar copper contents of from 2 to 60 mol%. It was possible to see from powder X-ray diffraction that copper(II) was dispersed in the zirconia matrix at levels up to about 20% depending on the synthetic method. And it was shown that base-catalytic activity of these materials correlated with the amount of fully incorporated copper(II). Activities of these were generally higher than the mixed metal oxides made from the LDHs. For comparison, another, different, approach to incorporating basicity in oxide supports was examined, in which alkylamino groups were tethered to silica supports, specifically a mesoporous molecular sieve form of silica, SBA-15. The activity of these materials were compared with those of the copper(II) based catalysts in the Henry reaction between nitromethane and benzaldehyde. An advantage of these catalysts was exploited by coordinating palladium(II) to the amine groups at different levels to impart oxidation catalytic activity. The resultant materials, in which only part of the amine functionality was coordinated by palladium(II), were tested as bifunctional catalysts, for combined oxidation and base catalytic activity, in the two step reaction between benzyl alcohol and nitromethane, which proceeds via an oxidation step to benzaldehyde followed by a base-catalysed step. The overall conclusion was that copper(II) is effective at imparting base catalytic activity to a range of support oxides, and that it does not have significant activity towards oxidation reactions., contrary to some claims in the literature. Oxidation activity can be obtained alongside base activity by preparing bifunctional catalysts but only through a different approach.
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Woodford, Julia Jane. "Hierarchical nanoporous solid base catalysts for biodiesel synthesis." Thesis, Cardiff University, 2013. http://orca.cf.ac.uk/51927/.
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The discovery of alternative solid base catalysts to replace homogeneous catalysts currently used in the industrial synthesis of biodiesel could remove the need for atom and energy inefficient routes to the desired biofuel product, and allow for the possibility of a continuous production process. Hydrotalcites have shown promise as catalysts in the transesterification of triglycerides with methanol to form biodiesel; however their activity is hampered by slow diffusion of the bulky triglycerides through the microporous hydrotalcite structure and poor accessibility of the active sites. This thesis has examined the synthesis of hydrotalcites via novel routes in an attempt to improve base site accessibility to triglycerides feedstocks in order to enhance catalytic performance. Macropore introduction into MgAl hydrotalcites helps to overcome mass transport limitations and increase their activity 10-fold for the transesterification of olive oil. Hydrotalcites prepared on an alumina support through a novel grafting and hydrothermal protocol form well-ordered crystallites on the high surface area oxide support. The resulting hydrotalcite-coated aluminas exhibit activities comparable to macroporous hydrotalcites of similar Mg:Al stoichiometries. Hydrotalcites prepared on alumina-grafted SBA-15 and macroporous-mesoporous SBA-15 employing the same grafting and hydrothermal synthesis are also extremely active in triglyceride transesterification, with the hierarchical macroporous-mesoporous outperforming the purely mesoporous SBA-15 support. Comparative studies on non-porous solid bases derived from nanocrystalline MgO reveal that Cs doping via co-precipitation confers superior activity for tributyrin transesterification. X-ray absorption spectroscopy has been applied to probe the local chemical environment of Cs atoms within such Cs-doped MgO, and the catalytically active phase identified as Cs2Mg(CO3)2(H2O)4. Cs-MgO is an order of magnitude more active for the transesterification of bulky triglycerides and olive oil than the undoped, parent MgO nanocrystals.
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Zhang, Honglei. "Solid acid catalysts for sustainable production of biodiesel." Thesis, University of Nottingham, 2016. http://eprints.nottingham.ac.uk/33697/.
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Homogeneous acid catalysts, such as H2SO4, are playing significant roles in catalytic processes for the manufacture of a wide range of important chemicals such as pharmaceuticals, petrochemicals, and fragrances. However, the use of liquid acid catalysts is normally associated with engineering problems, such as the difficulty in its separation from products, the formation of large quantity of wastewater and corrosion to the equipment. Consequently, it is desirable to develop highly active, inexpensive, green and reusable heterogeneous acid catalysts for various applications. To date, the R&D of heterogeneous solid acid catalysts has become a forefront of scientific research and attracted worldwide attentions. The aim of this work is to develop novel heterogeneous catalysts that can be used to replace homogeneous catalysts in the esterification of free fatty acid with methanol for biodiesel production. Three types of heterogeneous solid acid catalysts, i.e., sulfonated cation-ion exchange resin (s-CER)/polyvinyl alcohol (PVA) catalytic membranes, sulfur-rich graphene oxide catalysts, and sulfonated hydrothermal carbon microspheres (S-HTC), were prepared in this study. These solid acid catalysts were systematically characterized by using techniques, such as Field Emission Scanning Electron Microscope (FESEM), Transmission Electron Microscope (TEM), X-Ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Raman, X-Ray Photoelectron Spectroscopy (XPS), Elemental analyzer (EA), Energy Dispersive X-Ray Spectroscopy (EDX), nitrogen adsorption, acid-base titration, and Thermogravimetric Analyzer - Differential Scanning Calorimeter (TGA-DSC), to show chemical and physical properties of the catalysts. Results of these characterisations were then used to study the relationship between the catalytic activities of the solid acidic catalysts and their physical and chemical properties. Sulfonated-cation exchange resin (S-CER)/Polyvinyl alcohol (PVA) catalytic membrane has been studied in the esterification under a free fatty acids of 20 g, methanol/FFAs mass ratio of 2.5:1 (equivalent to molar ratio 29:1); a catalytic membrane loading of 4 g; a mechanical stirring rate of 360 rpm; reaction temperature of 338 K; and a reaction time of 8 h. Sulfonated cation exchange resins (s-CER) have been widely studied for the catalysis of esterification of FFAs to produce biodiesel with water as the only by-product. However, the water produced has strong affinity to sulfonate groups in s-CER, which blocks the reactive sites for esterification and thus reduces the activity of the s-CER. PVA has much stronger absorption preference of water than s-CER and has very low selectivity for the reactants (FFAs and methanol), which enables the continuous removal of the produced water and liberation of the reactive sulfonate sites in s-CER for catalysis. The catalytic activity of the membrane was compared with that of sulfuric acid and s-CER alone. With s-CER/PVA as the catalyst, the FFAs conversion increased from 80.1 % to 97.5 % after 8 hours’ reaction. The turnover frequency (TOF) increased by more than 3.3 times. The TOF of s-CER/ PVA were also 2.6 times higher than that of sulfuric acid. The reusability of the s-CER/PVA was also enhanced because the water yielded was largely removed by the PVA. Moreover, this catalyst has high reusability at moderate reaction temperatures with no need of catalyst re-treatment during the reuse process. The reaction mechanism for the esterification catalyzed by the s-CER/PVA was also studied. It was found that the PVA played two major roles in the esterification process, supporting the catalyst for separation and reutilization; liberating the –SO3H sites for esterification by adsorbing the water yielded and promoting the forward reaction. Different types of sulfur-rich graphene oxide (GO-S) catalysts were prepared and tested in the esterification of oleic acid with methanol. Catalytic activity of the GO-S was compared with sulfuric acid, two other GO samples and nine carbon-based solid acid catalysts prepared using other methods. The GO-S showed the highest catalytic activity and reusability. The TOF of the GO-S was about 3 times higher than that of the sulfuric acid. There are two key properties leading to the high catalytic performance: 1) the 2-D layered structure which allows reactants enter the internal space of the GO-S and access the catalytic active sites easily; and 2) the synergic effect between the surface –SO3H and –COOH groups. A GO/PES catalytic membrane was also prepared by immersion phase inversion method and employed in the esterification of oleic acid with methanol for biodiesel production. The reaction conditions were studied and determined to be: GO/ PES mass ratio 1:5, membrane annealing temperature 150 °C, membrane thickness 0.1 mm, membrane dimension 0.5 cm ×0.5 cm, catalytic membrane 4 g, reaction temperature of 65 °C, and the methanol/oleic acid mass ratio 2.0:1. The sulfonated hydrothermal carbon microspheric (S-HTC) material was also employed in the esterification of oleic acid with methanol. The reaction conditions were studied comprehensively to achieve the optimal yield of biodiesel under minimized production cost. The catalyst showed fairly high catalytic performance with a high yield of 92 % under the optimal reaction conditions: a methanol/oleic acid molar ratio of 12:1, a catalyst loading of 0.25 g, a reaction temperature of 65 °C, a reaction time of 8 hours and a mechanical stirring rate of 360 rpm. The S-HTC also showed very good catalytic recyclability with a yield of approximate 84 % after five runs. Future work will be done to test the catalytic performance in commercial large-scale production of biodiesel. Several works are needed to solve the problem that GO-S and S-HTC are hard to be recycled from the reaction mixtures.
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Frattini, Lucia. "Polyoxometalates as solid acid catalysts for sustainable chemistry." Thesis, Aston University, 2017. http://publications.aston.ac.uk/33384/.
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Polyoxometalates, also known as heteropolyacids (HPA), are solid acids widely utilised in heterogeneous catalysis. The physicochemical properties of HPAs facilitate surface-type or bulk-type reactions, dependent on substrate polarity. For the latter, the gas-phase dehydration of ethanol was investigated representing an environmentally friendly solution to produce bio-ethylene, a key compound to the chemical industry; while for the former, the solventless liquid-phase isomerisation of α-pinene was studied due to the widespread applications of its derivates. Supported HPAs, exhibiting the Keggin structure, were prepared on commercial low surface area fumed silica and mesoporous high surface area SBA-15 via wet impregnation technique to elucidate structure-activity behaviours in both catalytic systems relative to their bulk equivalents. In addition, different types of HPAs, phosphotungstic acid (HPW), silicotungstic acid (HSiW) and phosphomolybdic acid (HPMo), were studied to observe the role of acid strength on product distribution. The successful synthesis of supported HPAs was confirmed by multiple characterisation techniques, revealing an inverse relationship between loading and dispersion which is further promoted through the use of mesoporous SBA-15 as the support, whereas non-porous fumed silica induced agglomeration which in turn increases the degree of crystalline water present in the HPAs. n-Propylamine TPD evaluated acid strength decreases in the order of HPW > HSiW > HPMo, which is independent of support. Support choice did not influence selectivity in either reaction, but did impact greatly on catalytic activity, imparting significant reaction rate and turnover frequency enhancement. For surface-type reaction, SBA-15 showed to be the optimal support due to greater active sites accessibility, whereas in the case of the bulk-type reaction, the fumed silica based materials, with larger 3D HPAs structures, even at low loadings, showed superior performance. Product distributions were affected through the choice of HPA, with higher selectivity towards camphene, for α-pinene isomerisation, and ethylene, for ethanol dehydration, observed over the HPW catalysts.
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Dagade, S. P. "Nitration of aromatic compounds over solid acid catalysts." Thesis(Ph.D.), CSIR-National Chemical Laboratory, Pune, 2002. http://dspace.ncl.res.in:8080/xmlui/handle/20.500.12252/2855.
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Harris, Gari Stuart. "Surface profile imaging of spinel catalysts." Thesis, University of Oxford, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.258433.
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Platon, Alexandru. "Characterization of solid acid catalysts for isobutane/butene alkylation." Online access for everyone, 2004. http://www.dissertations.wsu.edu/Dissertations/Fall2004/a%5Fplaton%5F100104.pdf.
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Davison, Andrea Dianne. "Synthesised sulfonic solid acid catalysts for liquid phase reactions." Thesis, University of Huddersfield, 2008. http://eprints.hud.ac.uk/id/eprint/5014/.
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The move to use heterogeneous solid acid catalysts as new, cleaner, renewable catalysts for liquid phase reactions is at the forefront of scientific research, with the focus on the ability to tailor and improve the physical and chemical properties of the catalysts in order to tailor their acidity to catalytic activity for specific liquid phase reactions. The aim of this project was to determine the role of the support in imparting acidity and catalytic activity in liquid phase reactions to three different types of supported solid acid catalyst; polystyrene, silica and a fluorinated hydrocarbon polymer. For the sulfonic acids supported on silica, two main synthesis routes (grafted and co-condensed) with the use of two alternative tethers (propyl, phenyl and also an additional non acidic tether) were compared. Of the synthesised materials, structural properties were characterised and compared using several techniques. Nitrogen adsorption was used in order to ascertain the pore size and distribution, X-ray diffraction to determine the long range order, elemental analysis to determine the relative sulfur content and X-ray phototelectron spectroscopy to analyse the environment of the sulfur in order to establish successful acidification. Surface acidities of all three supported sulfonic acids were better characterised and compared using ammonia adsorption calorimetry. The extent of the adsorption and molar enthalpies of ammonia adsorption (ΔHadsn) were interpreted in terms of abundance, accessibility and strength of surface acid sites. Catalytic activities were measured and compared using the isomerization of α-pinene liquid phase reaction. In brief, the main findings of this project indicate that the commercially available fluorinated polymer Nafion® resin demonstrated the highest acid strength and much higher specific catalytic activities compared to the other supported sulfonic acids. The acid strengths on polymeric and silica supports were similar, with poor catalytic activities. The routes used in order to synthesise, characterise and acidify the supported sulfonic acids were successful.
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Mort, Catherine Julia. "Synthesis of 2,6-dimethylnaphthalene and analogues over solid catalysts." Thesis, Swansea University, 2005. https://cronfa.swan.ac.uk/Record/cronfa42925.
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The first part of Chapter 1 highlights the advantages and uses of heterogeneous inorganic solids as catalysts. A brief review of various microporous and mesoporous solids that have been employed as catalysts is given. Chapter 2 describes the attempted three stage synthesis of 2,6-dimethylnaphthalene from p-xylene and crotonic acid using zeolite catalysis. It was found that the zeolite catalysts were not sufficiently active to facilitate the reaction. Chapter 3 describes the alkoxyalkylation of naphthalene over zeolite catalysts to obtain an intermediate for use in the production of polyethylenenaphthalate. The main body of work focuses on the optimisation of the methoxymethylation of naphthalene. When HM zeolite was employed under optimised conditions, a 45% yield of mono(methoxymethyl)naphthalene with a 2/1 of 3.0 and a 45% yield of bis(methoxymethyl)naphthalene with a 2,6/2,7-ratio of 17.0 were observed. The major isomer was found to 2,6-bis(MM)N. Chapter 4 describes the methoxymethylation of naphthalene over HM zeolite. Under optimised conditions, a 57% yield of bis(MM)N with a 2,6/2,7-ratio of 9.7 were observed. 2,6-bis(MM)N was the major isomer observed. Part 1 of Chapter 5 focuses on the ethoxymethylation of naphthalene over HM zeolite. Under optimised conditions, (ethoxymethyl)naphthalene was observed in a 19% yield with a 2/1 ratio of 9.9. In Part 2, the ethoxymethylation of 2-(ethoxymethyl)naphthalene is discussed. A 26% yield of bis(EM)N was observed under optimised conditions. Only one bis(EM)N isomer, which was thought to be the desired 2,6-isomer, was observed.
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Kalita, P. "Carbon-carbon bond formation reactions using solid porous catalysts." Thesis(Ph.D.), CSIR-National Chemical Laboratory, Pune, 2007. http://dspace.ncl.res.in:8080/xmlui/handle/20.500.12252/2609.
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Mayadevi, S. "Adsorption and mass transfer in solid catalysts and adsorbents." Thesis(Ph.D.), CSIR-National Chemical Laboratory, Pune, 1991. http://dspace.ncl.res.in:8080/xmlui/handle/20.500.12252/5827.
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Di, Jiexun. "Development of highly active internal steam methane reforming catalysts for intermediate temperature solid oxide fuel cells." Thesis, University of Oxford, 2013. http://ora.ox.ac.uk/objects/uuid:a36ce531-e7b2-48fb-a59b-dbca6b435643.
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Fuel processing is one of the essential parts for development of intermediate solid oxide fuel cells (IT-SOFC). Natural gas (methane) is considered as the most abundant and cost effective fuel for the production of hydrogen for IT-SOFC. The primary aim of this thesis is to use a novel precursor material—layered double hydroxide (LDH) – for developing a new type of cost effective, highly active and long lasting catalyst which can reform natural gas in IT-SOFC anode environment. Small amount of noble metals Pd, Rh and Pt are used as promoters to enhance the catalyst’s performance as while maintaining the cost relatively low. The research objectives are achieved by a series of studies including catalysts synthesis, characterisation and the catalytic activities. The thesis initially gives a comprehensive review on fuel cell and SOFC technology, steam methane reforming and reforming catalyst to provide better understanding of the research. Experimental studies include the effects of the synthetic conditions of the LDH precursors and thermal treatments on the physical, chemical behaviours and catalytic activities of the catalysts and promotional effects by noble metals. The LDH derived catalysts compositions, promoter quantities and operating conditions are optimised for the best performance in the IT-SOFC anode environment. A new method for the development of precursor sol for easy coating of the anode is developed and studied. The sol preparation is achieved by acid attack. The sol developed is found to produce better coating and has very high catalytic properties after activation. The catalysts developed were tested for their stability and self-activation ability to ensure its use in the commercial cells. The findings of the present study indicate that the catalysts developed show excellent catalytic performance and these catalysts have very high potential for further commercialisation in IT-SOFC.
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Anderson, Bruce Gordon. "Methane-olefin coupling using supported-nickel and solid superacid catalysts." Thesis, University of Ottawa (Canada), 1993. http://hdl.handle.net/10393/7900.
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In this thesis, we have investigated the coupling of methane with olefins, such as ethylene and propylene using silica-supported nickel and sulphate-promoted zirconia-silica catalysts. Control experiments over hydrogen-reduced Ni/SiO$\sb2$ in which propylene was co-fed with helium rather than with methane resulted in increased propylene conversions and in an increase of the yields of propane, C$\sb2$'s and C$\sb4$'s. It was concluded that the production of C$\sb4$'s was due to homologation or metathesis reactions, rather than to methane coupling. Variation of the temperature of the methane preactivation treatment from 350$\sp\circ$C to 600$\sp\circ$C revealed an increased CH$\sb4$ conversion from approximately 1% at 350$\sp\circ$C to 60% at 600$\sp\circ$C. Subsequent reaction of $\rm C\sb3H\sb6/CH\sb4$ mixtures over these catalysts at 350$\sp\circ$C revealed that there was virtually no activity over the former catalyst and very little over the latter. However, catalysts activated between 400$\sp\circ$C and 500$\sp\circ$C showed very similar activities. Experiments in which helium was co-fed with propylene rather than methane over CH$\sb4$-preactivated catalysts suggested that the same processes were responsible for C$\sb4$ production over CH$\sb4$-reduced NiO/SiO$\sb2$ and hydrogen-reduced NiO/SiO$\sb2$ i.e. propylene homologation and/or metathesis. Dissociatively adsorbed methane only served to block metal sites at which reactions could otherwise occur. Zirconia-silica, like many binary oxide mixtures, possesses enhanced surface acidity relative to its parent components. TPD experiments using NH$\sb3$ found that samples of 5, 10, and 20 wt.% ZrO$\sb2$/SiO$\sb2$, previously activated by evacuation at 450$\sp\circ$C, contained a similar amount of surface acid sites, 260 $\mu$mole/g sample. XRD analysis revealed no peaks due to crystalline phases following calcination at 450$\sp\circ$C, suggesting that these materials were amorphous, even with zirconia loadings as high as 20 wt.%. Infrared analysis of 10 wt.% ZrO$\sb2$/SiO$\sb2$ with sulphate loadings ranging from 100 to 1000 $\mu$mole/g revealed that the nature of the surface sulphate species was dependent on the temperature of activation. IR analysis using NH$\sb4$ as a probe revealed that both Lewis and Bronsted acid sites existed after 500$\sp\circ$C activation. The amount of each type of acid site appeared to increase with increased sulphate loading. The acidity of 10 wt.% ZrO$\sb2$/SiO$\sb2$ with various loadings of sulphate was measured by gravimetric ammonia adsorption following evacuation at various temperatures. The amounts of irreversibly adsorbed ammonia were found to increase with increased sulphate loading at 25, 100, and 200$\sp\circ$C. Attempts to measure the amount of irreversible adsorption at temperatures greater than 200$\sp\circ$C were hampered by weight loss due to sulphate. Thus, precise measurement of the number of acid sites at high temperature was not possible. Sulphate-promoted ZrO$\sb2$/SiO$\sb2$, previously activated by evacuation at 500$\sp\circ$C, was tested as a catalyst for the coupling of methane and ethylene (or propylene) in a fixed-bed reactor at atmospheric pressure and at temperatures ranging from 225 to 275$\sp\circ$C. All experiments were hampered by rapid deactivation of the catalyst (within 35 minutes on stream) due to oligomerization. Only minute quantities of propane were detected. Reactions of methane alone showed that it also interacted strongly with the catalyst, leading to deactivation. (Abstract shortened by UMI.)
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Yang, Yong. "Preparation, characterization and catalytic properties of strong solid acid catalysts." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape3/PQDD_0024/NQ52268.pdf.
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Kemp, Thomas F. "Solid state NMR studies of inorganic pigment materials and catalysts." Thesis, University of Warwick, 2008. http://wrap.warwick.ac.uk/55820/.
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The research conducted can be split into three major regions; pigment material, a simulation program called QuadFit and mesoporous oxides. There has also been some extra work conducted on a catalyst for partial hydrogenation of vegetable oils. Various techniques have been used on the different systems including XPS, STEM and 77Se, 17O, 93Nb, 15N, 119Sn, 27Al, 115In and 63,65Cu static and MAS NMR. The pigment materials consist of a series of materials which are grouped under the F-Colours project. The pigments consist of sulphur doped tin niobates, copper indium sulphur selenide doped zinc selenides, sulphur doped tin tungstates and colloidal gold and silver enamels. The sulphur doped tin niobate study shows a conversion from foordite to pyrochlore and also where the sulphur sits in the structure. The copper indium sulphur selenide doped zinc selenide study shows the indium and copper moving into the zinc selenide as copper indium pairs. However, how the pairs sit in the structure remains undetermined. The sulphur doped tin tungstate study shows that the sulphur acts as a promoter for the beta phase rather than the desired alpha phase. The enamels based on gold and silver show that the tin site does not determine the colour of the enamel and the silver-gold association is likely to be the dominant factor. Mesoporous oxides show a link between the amount of mesoporous structure and their temperature stability. The nitrogen spectra of the template in the material shows that in the mesoporous silicate (which has the largest surface area) there is a breakdown of the amine into NH groups which does not appear in the other mesoporous materials. This could lead to a method of increasing the surface area of the other mesoporous oxides. QuadFit has the ability to simulate quadrupolar and CSA interactions with distributions of interactions whilst static and the quadrupolar interaction with distributions under MAS. The program is written in Java so will run on most platforms and also has near perfect stability.
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Kosinski, Marcin Robert. "Nanomaterials for solid oxide fuel cell electrolytes and reforming catalysts." Thesis, University of St Andrews, 2011. http://hdl.handle.net/10023/2588.
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In this work, a broad range of analytical methods was applied to the study of the following three materials systems: yttria-stabilised zirconia (YSZ), samarium-doped ceria (SDC) and SDC-supported metal catalysts. YSZ and SDC were studied in the light of their application as solid electrolytes in Solid Oxide Fuel Cells. The SDC-supported metal catalysts were evaluated for application in the reforming of methanol. The conductive properties of YSZ pellets derived from powders of different Y contents and particle size ranges were investigated using Impedance Spectroscopy (IS). Comparative studies of the crystallography (by X-ray Powder Diffraction (XRD)), morphology (by Scanning and Transmission Electron Microscopy (SEM, TEM)), chemical composition (by Energy Dispersive X-ray Spectroscopy (EDX) and Inductively Coupled Plasma Mass Spectroscopy (ICP-MS)) and sintering behaviour (dilatometry) were employed in the overall assessment of the conductivity results collected. Detailed studies of three SDC compositions were performed on nanopowders prepared by a low temperature method developed in the Baker group. Modifications led to a simple and reliable method for producing high quality materials with crystallites of ~10 nm diameter. The products were confirmed by XRD and TEM to be single-phase materials. Thermogravimetric analysis, dilatometry, specific surface area determination, elemental analysis and IS were carried out on these SDC powders. The relationships between particle size, chemical composition, sintering conditions and conductivity were studied in detail allowing optimum sintering conditions to be identified and ionic migration and defect association enthalpies to be calculated. Finally, the interesting results obtained for the SDC nanopowders were a driving force for the preparation of SDC-supported metal catalysts. These were prepared by three different methods and characterised in terms of crystallographic phase, specific surface area and bulk and surface chemical composition. Isothermal catalytic tests showed that all catalysts had some activity for the reforming of methanol and that some compositions showed both very high conversions and high selectivities to hydrogen. These catalysts are of interest for further study and possibly for commercial application.
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Holland, David Richard. "Allylation of glycine equivalents during solid phase peptide synthesis." Thesis, University of Bath, 2000. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.311452.
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Gardy, Jabbar Lashkeri Ismail Agha. "Biodiesel production from used cooking oil using novel solid acid catalysts." Thesis, University of Leeds, 2017. http://etheses.whiterose.ac.uk/18086/.
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Damage to the environment as a consequence of exploration, production, imminent depletion, use of fossil fuels and concerns over climate change (increasing lifecycle greenhouse gas emissions), has increased the need for a more eco-friendly, renewable and sustainable source of energy. The level of biodiesel production has been increasing over the last twenty years, reflecting a rapid rise in demand due to its availability, renewability, lower gas emissions, non-toxicity, and its biodegradability. The impact of CO2 emissions on climate change, worldwide industrialisation, countries not having oilfields and need for a strategic and alternative source of energy have also driven an ever increasing demand. Biodiesel is mainly produced in industry by the transesterification process of triglycerides with low molecular weight alcohols using homogenous acid or base catalysts. However, the biodiesel industry faces some significant challenges; (i) high cost of biodiesel feedstock and (ii) the cost of biodiesel processing, including separation, purification and the neutralisation of by-products. These issues can be resolved with catalysts that are highly tolerant to moisture and free fatty acid (FFA) in feedstock oils. Solid acid catalysts have shown promise as catalysts in the simultaneous esterification and transesterification to overcome these issues. Here, lab-scale biodiesel production from simultaneous esterification and transesterification of used cooking oil (UCO) over different developed novel solid acid catalysts has been investigated. The synthesised catalysts, including TiO2/PrSO3H, Ti(SO4)O and SO_4^(2-)/Fe-Al-TiO2, were characterised via XRD, SEM, TEM, TEM-EDS, EDS-mapping, FT-IR, DRIFT-pyridine, TPD-MS with n-propylamine, TGA/FT-IR, CHNS analysis, DSC, TGA, N2 porosimetry, VSM and XPS. The effect of different process parameters on the fatty acid methyl ester (FAME) yield over different catalysts was also studied, including the effect of reaction temperature, mole ratio of methanol to UCO, time of esterification/transesterification, and amount of catalyst to UCO loading in order to achieve the optimum process conditions to obtain the highest FAME yield. Furthermore, a significant aim was to design a highly active, low cost, stable, easy recoverable, FFA tolerant and highly re-usable solid acid catalyst for biodiesel fuel production. It was found that SO_4^(2-)/Fe-Al-TiO2 performs well under optimum conditions of 2.5 h of reaction time, 3 wt% of synthesised magnetic catalyst to UCO ratio, 10:1 methanol to UCO mole ratio and 90 oC reaction temperature for simulations esterification and transesterification processes. A massive improvement in catalytic stability, easy recovery (using external magnetic field), high tolerance to FFA and water have been achieved via the introduction of alumina and iron oxides to the catalyst support. The synthesised biodiesels from UCO over different solid acid catalyst processes were analysed in accordance to ASTM D6475 and EN14214 standard methods to determine characteristic fuel properties such as kinematic viscosity, density, flash point, FAME content, LAME content, and acid number.
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Stewart, Iain Hunter. "Supercritical alkylation of isobutane with 1-butene using solid acid catalysts." Thesis, University of Liverpool, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.367029.
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Lakshminarayanan, Nandita. "Investigation and development of electro catalysts for Solid Oxide Fuel Cells." The Ohio State University, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=osu1291134392.
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Kearney, Jonathan. "Cu/CeₓZr(₁₋ₓ)O₂ catalysts for solid oxide fuel cell anodes." Thesis, University of St Andrews, 2010. http://hdl.handle.net/10023/1845.
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Ce[subscript(x)]Zr[subscript(1-x)]O₂ mixed oxides of varying compositions were prepared by a sol-gel citrate complexion technique. In order to improve the catalytic activity of the oxides they were impregnated with copper using two different impregnation techniques. The bare oxides and copper impregnated samples were investigated using a range of Temperature Programmed (TP) techniques, in an attempt to establish their effectiveness as anode materials for solid oxide fuel cells (SOFCs) run on hydrocarbon fuels. In order to conduct the TP experiments a novel system was designed and constructed. The high Ce containing mixed oxides were shown to be reduced at lower temperature than high Zr content samples. TPRx experiments were employed to investigate which of the oxides was most prone to carbon deposition when reacted in methane, with the high ceria sample displaying the lowest level of carbon deposition. Lightoff experiments were undertaken to establish which oxide composition was the most active for methane oxidation. The activity of the oxides increased with ceria content up to 75 mole% (ZCe75), before decreasing for ZCe90. All the mixed oxides were shown to be more active for methane oxidation than CeO₂.
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Valancogne, Ingrid. "Synthesis of unnatural amino acids and dipeptides for potential catalysts." Thesis, University of Newcastle Upon Tyne, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.300361.
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Hemming, Beverley Faith. "Metal (IV) compounds as heterogeneous catalysts for the Baeyer-Villiger oxidation of ketones with hydrogen peroxide." Thesis, University of Liverpool, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.367275.
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Kaur, Jaspalne. "Friedel-Crafts acylation catalysed by heteropoly acids." Thesis, University of Liverpool, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.272747.
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Hissam, Jason C. "Characterization of nickel-substituted hexaaluminate catalysts." Morgantown, W. Va. : [West Virginia University Libraries], 2008. https://eidr.wvu.edu/etd/documentdata.eTD?documentid=5999.
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Thesis (M.S.)--West Virginia University, 2008.Title from document title page. Document formatted into pages; contains vii, 78 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 74-76).
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Al-Haq, Nazli. "Novel organo-bridged polysilsesquioxanes towards environmentally friendly solid acid and base catalysts." Thesis, Queen Mary, University of London, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.420569.
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Ramirez-Cabrera, Elvia. "Oxide catalysts for steam reforming of methane in solid oxide fuel cells." Thesis, Imperial College London, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.271143.
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Zhang, Yue, and 张悦. "Synthesis and characterization of zirconia based solid acid catalysts for biodiesel production." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2012. http://hub.hku.hk/bib/B49858828.
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Biodiesel is a promising renewable alternative fuel to fossil energy. For the biodiesel production from low-cost feedstock, a pretreatment step is essential, which is the esterification of free fatty acids (e.g. oleic acid) in the feedstock in order to avoid soap formation and minimize catalyst deactivation. Sulfuric acid modified zirconia (H2SO4-ZrO2) is known as an effective heterogeneous catalyst for esterification. However, due to rapid 〖SO〗_4^(2-) leaching, its reusability is low and its practical use is thus largely hindered.
Zirconia supported on silica (ZrO2-SiO2) serves as a kind of non-sulfated zirconia catalyst against the leaching of the active species. Moreover, the silica support offers a large surface area and excellent thermal stability, which can accommodate a number of active zirconia species. Furthermore, there are Zr-O-Si bondings at the contact area between ZrO2 and SiO2, which might result in the formation of a new strong acid species and induce an increase of the zirconia acidity accordingly. Herein, two types of ZrO2-SiO2 catalysts were prepared, by using the reverse microemulsion method and sol-gel-hydrothermal method, denoted as ZrO2-SiO2-ME and ZrO2-SiO2-SG, respectively. The as synthesized ZrO2-SiO2 were characterized by TEM, SEM, EDX, XRD, BET and IR. ZrO2-SiO2-ME demonstrated a good dispersion of ZrO2 nanoparticles, encapsulating in the monodispersed SiO2 host matrix, while ZrO2-SiO2-SG possessed the SiO2 support with a mesoporous structure, with an average pore size of ~7 nm and a surface area of 418 m2/g. The catalysts both exhibited excellent catalytic activity and stable performance in the esterification of oleic acid.
Besides non-sulfated zirconia, sulfated zirconia catalysts other than traditional H2SO4-ZrO2 were also developed as solid acid catalysts for biodiesel production. Two sulfur-containing strong acids, chlorosulfonic acid (HClSO3) and (NH4)2SO4, were employed to acidify ZrO2, and two sulfated zirconia catalysts were prepared accordingly, namely HClSO3-ZrO2 and S-ZrO2. They were characterized by SEM, EDX, XRD, BET, IR, TGA and NH3-TPD. Comparing with H2SO4-ZrO2, HClSO3-ZrO2 and S-ZrO2 contained higher sulfur content and more acid sites. More importantly, both HClSO3-ZrO2 and S-ZrO2 demonstrated high catalytic activity and excellent durability in the esterification of oleic acid.
It is known that consecutive esterification and transesterification reactions are suitable for direct biodiesel production and acetylation of glycerol enables the conversion of this biodiesel byproduct to a biofuel additive. Therefore, all the above mentioned catalysts were examined to compare their catalytic abilities in these reactions. Among the four catalysts, HClSO3-ZrO2 exhibited the highest catalytic activity in both reactions under optimal conditions.
The thesis work here described the preparation and characterization of four types of ZrO2-based solid acid catalysts. Their catalytic activities were thoroughly investigated upon the several essential steps in biodiesel production. In addition, the synthesis condition-activity relation was studied and the synthesis and reaction conditions were delicately tuned.published_or_final_version
Chemistry
Doctoral
Doctor of Philosophy
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Alsalme, Ali Mohammed. "Solid acid catalysts based on heteropoly acids for conversion of renewable feedstocks." Thesis, University of Liverpool, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.539488.
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The aim of this work is to investigate homogeneous and heterogeneous catalysis by HPAs for the conversion of renewable feedstocks. This includes the preparation, characterisation and testing of a range of acidic solid materials such as bulk HPAs, CS2.sHo.sPW12040and the acidic composites comprising H3PW12040 (HPW) supported on Nb20s, Zr02 and Ti02. The HPW supported on Ti02, Zr02 and Nb20s were prepared by impregnation method and then characterised regarding their acid properties and the chemical structure of HPA on the catalyst surface, compared to "standard" HPA catalysts such as bulk and silica-supported H3PW12040 and CS2.5HO.SPW12040In. contrast to the parent acid H3PW12040 and CS2.sHo.sPWI2040, possessing strong Brensted acid sites, the catalysts supported on Ti02, Zr02 and Nb20s possess both Brensted and Lewis acid sites, with the latter mainly originating from the oxide support. These catalysts possess weaker acid sites than H3PW 12040and CS2.sHo.sPW12040,with their acid strength being similar to that of acidic zeolites. The catalytic activity (turnover frequency) in gasphase isopropanol dehydration decreases in the order: H3PW12040> CS2.sHo.sPW12040> 15%H3PW12040/Si02 > 15%H3PW120401Ti02 » 15%H3PW120401Nb20S > 15%H3PWI2040/Zr02, which is in line with the acid strength determined by NH3 adsorption calorimetry. 31p MAS NMR and FTIR indicate an increasing interaction between support and HPA in the following order: Si02 < Ti02 < Nb20s, Zr02, whilst the strength of acid sites decreases in that order. Esterification of hexanoic acid and transesterification of ethyl propanoate and ethyl hexanoate with excess methanol (1:20 molar ratio) were tested at 60 QC and ambient pressure with a range of HPA catalysts in homogeneous and heterogeneous systems in comparison with conventional homogeneous and solid acid catalysts such as H2S04, Amberlyst-15 and zeolites HY and H-Beta. In these reactions, the intrinsic catalytic activity (turnover frequency, TOF) of HPA catalysts is significantly higher than that of the conventional acid catalysts. The TOF values decrease with decreasing catalyst acid strength in the order: H3PW12040~ CS2.sHo.5PW12040> ~SiW 12040> 15%H3PW12040INb205, 15%H3PWI2040/Zr02, 15%H3PWI2040/Ti02> H2S04> HY, H-Beta> Amberlyst-15. Supported HPA catalysts suffer from leaching and exhibit significant contribution of homogeneous catalysis by the leached HPA. The isomerisation of a-pinene is studied in the gas phase over solid HPA catalysts in a fixed bed continuous flow reactor at 200°C and ambient pressure. The reaction yields camphene as the main product in a mixture with monoterpene byproducts such as limonene, terpinolenes, terpinenes, p-pinene, p-cymene and others. The strong Brensted solid acids exhibit high initial activities, but suffer from catalyst deactivation, resulting in low camphene yields. Conversely, the HPA catalysts supported on Nb20S, Zr02 and Ti02, although weaker acids, show more stable performance in a-pinene isomerisation.
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Elbakush, Mohamed Mostafa. "Structure and function relationship in novel solid organic-inorganic hybrid base catalysts." Thesis, University of Huddersfield, 2016. http://eprints.hud.ac.uk/id/eprint/30285/.
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The overall objective of this study was to prepare and optimise solid base catalysts for liquid phase reactions, based on silica support materials functionalised with alkyl amine groups. The study included an investigation of the effect of the pore volume, surface area and the surface chemical characteristics of the silica support on the catalyst performance. The role of surface silanol groups remaining on the silica surface after functionalisation working cooperatively with basic amine groups was also studied. A series of silica gel supports, together with a commercially-available ordered mesoporous silica, SBA-15, were functionalized with tethered aminopropyl groups. Activities were measured in the nitroaldol reaction between nitromethane and benzaldehyde to afford nitrostyrene, and the Knoevenagel condensation reaction between benzaldehyde and ethyl cyanoacetate to form ethyl-2-cyano-3-phenylacrylate. The results showed large variations in optimum activity depending on the support material, and its porosity in particular. All support materials exhibited an optimum catalyst loading which depended on support surface area, generally coinciding with complete coverage of the surface with a single layer of catalytic groups, based on a nominal surface area occupied by the three tethering groups linking each propylamine group to the surface. Further experiments were performed with catalytic groups tethered by one and by two (rather than three) groups, which occupy less space on the support surface. In addition, the possible role of silanol groups was investigated by capping free silanols with non-polar methyl groups using trialkoxymethylsilane. This was found to invariably reduce the activity of the supported amine groups. Whether the role of free silanol groups was through an acid-base cooperative catalytic process or whether it was due to the hydrophilicity they impart to the catalyst surface was investigated by altering the polarity of the reaction solvent/solution. The conclusion was that the role of free silanol groups is to provide mildly acidic groups in a cooperative mechanism rather than simply through control of surface hydrophilicity/hydrophobicity.
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Choi, Hyunkyu. "Perovskite-type oxide material as electro-catalysts for solid oxide fuel cells." The Ohio State University, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=osu1354652812.
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Lu, Mengnan. "New technology development for advanced "Clean" solid catalysts for Fischer-Tropsch synthesis." Thesis, Lille 1, 2015. http://www.theses.fr/2015LIL10108.
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La synthèse Fischer-Tropsch (FT) convertit le gaz de synthèse en hydrocarbures liquides avec le catalyseur au cobalt pour les nouveaux carburants alternatifs ultrapropres. Les catalyseurs pour la synthèse FT sont actuellement préparés par des moyens chimiques comme l'imprégnation etc. Toutes ces voies impliquent des solvants toxiques et retraitement à haute température. En raison du coût plus faible, d’une réduction des besoins en énergie et de la pollution de l'environnement, la mécano-chimique a un certain nombre d'avantages pour la synthèse de la catalyse hétérogène par rapport à des techniques classiques. Dans cette thèse, la méthode mécano-chimique a été utilisé pour préparer des catalyseurs au cobalt supportés par l’alumine, pour la synthèse FT. Contrairement à la préparation de catalyseur classique, le dépôt de phase active ne comportait aucun solvant. Le but de ce travail est d'obtenir des catalyseurs efficaces FT et de simplifier la synthèse de catalyseur en réduisant le nombre d'étapes de préparation. Le projet consiste par une méthode innovante de synthèse de catalyseurs en trois processus de travail mécaniques différents dans le contexte sec. Le processus mécano-chimique pour synthétiser le catalyseur pour la réaction FT a été développé. Les conditions de la technique de revêtement ont été identifiés par l'étude des conditions optimales. En outre, les caractérisations ont été étudiées pour comprendre les mécanismes derrière le dépôt de particules sur l’interface. Les tests de performances catalytiques ont été estimés dans un réacteur à lit mili-fixé; un algorithme d'optimisation des paramètres dans un processus mécanique a été réalisé par l'intermédiaire dérivant la formule cible sur l'énergieFischer–Tropsch (FT) synthesis converts syngas into liquid hydrocarbons over cobalt catalyst for new ultraclean alternative fuels. The syngas can be produced from both fossil and renewable resources. The catalysts for FT synthesis are currently prepared by chemical ways like impregnation etc. All these routes involve toxic solvents and high temperature retreatment. Because of lower cost, reduced energy requirements and environmental pollution, the mechano-chemistry has a number of advantages for the synthesis of heterogeneous catalysis compared to conventional techniques. In this study, the mechano-chemical method was used to prepare alumina supported cobalt catalysts for FT synthesis. Differently to the conventional catalyst preparation, the deposition of active phase did not involve any solvent in the proposed method. The goal of this work is to obtain efficient FT catalysts and to simplify catalyst synthesis by reducing the number of preparation steps. The project involves innovative method of synthesis of catalysts in three different mechanical working processes in dry context. The process of mechano-chemistry to synthesize the catalyst for FT reaction was developed. The operating conditions for the control of the coating technique were identified through optimal conditions study by statistical analysis. Moreover, characterizations were studied to understand the basic mechanisms behind deposition of particles on the interface. Catalytic performance tests were estimated in a mili-fixed bed reactor; Optimization algorithm of parameters in a mechanical process was carried out via deriving target formula about energy and material size
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Hager, Veit [Verfasser]. "Stability and Deactivation Behavior of Supported Ionic Liquid Phase (SILP) Catalysts and Solid Catalyst with Ionic Liquid Layer (SCILL) Catalysts in Transformation Reactions of Alkenes and Alkynes / Veit Hager." München : Verlag Dr. Hut, 2020. http://d-nb.info/1222351870/34.
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Rankin, Andrew Gordon McLaughlin. "Applications of multinuclear solid-state NMR spectroscopy to the characterisation of industrial catalysts." Thesis, University of St Andrews, 2018. http://hdl.handle.net/10023/12793.
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This thesis describes applications of advanced multinuclear solid-state nuclear magnetic resonance (NMR) experiments to the characterisation of industrially-relevant catalyst materials. Experiments on γ-Al₂O₃ introduce the use of solid-state NMR spectroscopy for the investigation of disordered solids. The existence of Al(V) sites on the surface of this material is demonstrated, showing that removal of adsorbed H₂O may facilitate a rearrangement effect in γ-Al₂O₃ that promotes the formation of these Al environments. A range of aluminium oxide-based supported metal catalysts has been investigated. Studies of these systems by ¹H and ²⁷Al solid-state NMR spectroscopy indicate that a metal-support interaction (MSI) exists between surface cobalt oxide crystallites and the γ-Al₂O₃ support, and is strongest for materials containing small, well dispersed Co oxide crystallites. It is shown that the hygroscopic nature of γ-Al₂O₃ allows the extent of the MSI to be visualised by ¹H MAS NMR, by observing the extent of the proton-metal oxide interaction resulting from the presence of adventitious adsorbed H₂O. The surface/bulk chemistry of Co spinel aluminate materials is also investigated. ¹H, ²⁹Si, ²⁷Al and ¹⁷O solid-state NMR techniques are used to gain insight into the structural nature of silicated alumina catalysts. The combination of isotopic enrichment and dynamic nuclear polarisation (DNP) surface-enhanced NMR spectroscopy can provide a definitive and fully quantitative description of the surface structure of Si-γ-Al₂O₃ (1.5 wt% Si), and the role of adventitious surface water is highlighted. Analysis of silicated aluminas prepared by “sequential grafting” and “single shot” approaches shows that silica growth on γ-Al₂O₃ follows two distinct morphologies. ¹⁷O gas exchange enrichment is also shown to be successful in facilitating ¹⁷O solid-state NMR studies of these materials. It is demonstrated that double (²⁹Si and ¹⁷O) enrichment of Si-γ-Al₂O₃ (1.5 wt% Si) can facilitate access to ²⁹Si-¹⁷O 2D correlation experiments, even at low silica loading. An exploratory investigation of Ti-alumina model catalysts has also been carried out using ¹H, ²⁷Al and ¹⁷O solid-state NMR spectroscopy. These studies indicate that Ti-γ-Al₂O₃ and Ti-Al M50 may be structurally distinct materials.
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Stranix, Brent R. "Functional polymers from (vinyl)polystyrene : solid-phase reagents, catalysts, supports and fluorescent sensors." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape16/PQDD_0006/NQ37028.pdf.
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Savill-Jowitt, Claire. "Catalytic and adsorbent properties of solid acid catalysts studied by ammonia adsorption microcalorimetry." Thesis, University of Huddersfield, 2007. http://eprints.hud.ac.uk/id/eprint/420/.
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Solid acid catalysts are becoming of great importance within the chemical industry and their acidity is of great interest, as this determines their application, plus many of their catalytic properties can also be directly related with their acidity. There has been a drive towards heterogeneous solid acid catalysts because of the environmental concerns with safe handling and disposal of mineral acid homogeneous catalysts such as H2SO4, and their separation from the product. Objectives of this work have been to study a range of solid acid catalysts and establish a relationship between catalyst strength, activity, and structure, and then identify the influence of solvent and type of reaction on the catalytic properties of the catalysts to be studied. Acid catalysts have been chosen to represent a cross-section of the various types of catalysts in use. The solid acid catalysts being investigated include sulfonated polystyrene ion exchange resins, acid activated clays, zeolites, and heteropoly acid (H3PW12O40) supported on carbon and mesoporous silica. Supported heteropoly acids have been prepared by Dr A Lapkin, University of Bath in the collaborative part of the project. Catalysts have been characterised in terms of their surface areas, pore diameters, pore volumes, and crystallinity from nitrogen adsorption, powder x-ray diffraction, cation exchange capacity, and elemental analysis. The acidity of these catalysts has been studied by NH3 adsorption microcalorimetry. NH3 is assumed to adsorb stoichiometrically on surface acid sites and the molar enthalpy of ammonia adsorption is assumed to reflect the strength of the acid sites. The catalytic activities of the catalysts have been measured using two Brønsted acid catalysed test reactions (rearrangement of α-pinene and the hydrolysis of ethyl acetate). The correlation between characterisation results and catalytic data has been examined with emphasis being placed on the relationship between acidity measurements and the reaction medium or solvent. Conclusions that can be drawn from this work are that NH3 adsorption microcalorimetry is a useful technique for studying surface acidity of solid acids and that it does allow for some correlation to be drawn between catalytic activity and acidity, with the aid of additional catalyst characterisation techniques.
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Ahmad, Husan. "Synthesis of Diazonium Perfluoroalkyl(Aryl) Sufonimide (PFSI) Zwitterions for Solid Acid Alkylation Catalysts." Digital Commons @ East Tennessee State University, 2015. https://dc.etsu.edu/honors/314.
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The final objective of this project is to create an environmentally friendly solid alkylation catalyst to replace the commercially available liquid acid catalysts, such as hydrofluoric acid and sulfuric acid, which are used in the petroleum industry. My research target is to synthesize the diazonium PFSI zwitterions, which can be chemically grafted on the silica as the solid alkylation catalyst. A 4-steps synthesis is designed to prepare the diazonium PFSI zwitterions. The first two steps were successfully completed in the lab. The first one is to prepare the starting material of 4-nitrobenzenesulfonamide from an ammonolysis reaction between 4-nitrobenzene sulfonyl chloride and ammonium hydroxide. And next, a base catalyzed coupling reaction was carried out with 4-nitrobenzenesulfonamide and commercially available perfluorobutane sulfonyl fluoride with nitrogen gas (N2) protection. The coupling product (I in Figure 1) was then purified by extraction and recrystallization. All chemicals in the synthesis procedure were characterized with proton NMR, fluorine NMR, Infrared (IR) spectroscopy and melting points.
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Mate, V. R. "Solid catalysts with modified REDOX properties for developing green processes for Fragrance chemicals." Thesis(Ph.D.), CSIR-National Chemical Laboratory, Pune, 2013. http://dspace.ncl.res.in:8080/xmlui/handle/20.500.12252/2182.
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Lemoine, Gaetan. "Comparison of different types of Zeolites used as Solid Acid Catalysts in the Transesterification reaction of Jatropha-type oil for Biodiesel production." Digital WPI, 2013. https://digitalcommons.wpi.edu/etd-theses/268.
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Sustainable energy management has become a high priority for many countries. A great majority of our energy stocks comes from non-renewable fossil fuels, which are currently dwindling. Biofuels are one of the most promising solutions being researched to address this urgent problem. In particular, using transesterified Jatropha curcas L. oil appears to be a promising method of producing biofuels due to several properties of the plant, such as the high oil yield of its seeds and the fact that it does not compete with food crops. The literature mentions many attempts of using zeolites as solid acid catalysts in transesterification reactions of vegetable oils with high free fatty acid (FFA) content. The acid catalysis prevents soap formation and emulsification, which can be observed in the basic process. The use of a solid catalyst makes the separation and purification of the final products steps easier to implement in comparison to catalysis in homogeneous conditions. However, the efficiency of the zeolite in the heterogeneous transesterification reaction of vegetable oil is not well-known yet and varies on the structure of the catalyst used. This project aims at better understanding the relationship between the type of zeolite used and the yield of this particular reaction using reconstituted Jatropha oil from Sesame seed oil, which has a similar composition. Five different types of zeolites were compared: Y, X, Beta, Mordenite & ZSM-5. Non-catalyzed reactions as well as homogeneously catalyzed - with H2SO4 - reactions were also implemented. Since we take advantage of the catalytic properties of different zeolites, the one that were not already in hydrogen form were ion-exchanged and the ion-exchanged species were then analyzed by Energy-Dispersive X-Ray spectroscopy (EDX). Three alcohol-to-oil ratios were tested at atmospheric pressure and at T=115°C for each catalyst in order to determine the influence of this ratio. All experiments were conducted in an airtight autoclave with butan-1-ol in order to obtain a biofuel whose cetane index is higher than regular petroleum-based diesels.