Esta dissertação mostra um estudo preliminar da preparação de precursores catalíticos a base de níquel (II) e de sua conversão em catalisadores de xerogéis contendo níquel (NS), bem como o estudo da sua atividade catalítica na reação de deslocamento gás-água. Esta reação foi escolhida como reação modelo para avaliar a atividade catalítica, em especial frente a adição do ácido fosfotungstico (HPW) como promotor catalítico e de organosilanos como agentes promotores da dispersão do Ni. Foram preparados catalisadores NS e NS-x (x = 0,5; 1; 2; 3; 5 e 10% em massa de HPW) via processo sol-gel. A caracterização estrutural foi realizada utilizando-se as técnicas de Energia Dispersiva de Raios X, Difratometria de Raios X, Redução a Temperatura Programada, Fisissorção de Nitrogênio, Espectroscopia de Absorção de Raios X e Espectroscopia de Absorção na Região do Infravermelho. Os testes catalíticos foram realizados no Laboratório de Catálise Heterogênea do IQSC/USP numa temperatura de 250-425 °C, em uma lin ha de reação acoplada a um cromatógrafo a gás para análises in situ dos produtos reacionais gasosos. Os resultados obtidos da primeira parte mostraram que a adição do HPW até 2% em massa de precursor catalítico leva a uma melhora gradual na atividade catalítica de 10 a 31 % medido pela taxa de conversão do CO. Contudo acima de 2% ocorre uma queda de atividade catalítica resultando num comportamento global da conversão de CO do tipo gaussiano com o máximo em 2%. Para explicar este comportamento um modelo qualitativo é proposto baseado na formação de fosfotungstato de níquel amorfo acima de 2%. Na segunda parte do trabalho, a concentração de HPW foi fixada em 2% e a temperatura de reação em 425 °C e foram adicionados organosilanos nitrogenados (amino e nitrila) para avaliar a sua capacidade de funcionar como agentes de dispersão do cátion metálico no precursor híbrido (Ormosil) e do metal no catalisador. O catalisador proveniente do precursor contendo grupo amina possui maior atividade catalítica que aquele contendo nitrila, porém ambos possuem menor atividade que o xerogel catalítico obtido de precursores sem grupos nitrogenados. Contudo, os catalisadores preparados a partir de Ormosils mostravam-se estáveis ao longo do tempo da reação estudada quando comparados com os xerogeis NS-x. / This dissertation describes the preparation of Ni (II)-based catalyst precursor material and its subsequent conversion to Ni-based xerogels catalyst as well as the catalytic activity of the resultant catalyst in water-gas shift reaction. The water-gas shift reaction was selected as a model reaction for the evaluation of catalytic activity of the prepared catalysts. The effect of addition of phosphotungstic acid (HPW) as an activity promoting agent and organosilane as dispersing agents of Ni was also studied. For this purpose, Ni-based catalyst (NS-x) containing various amounts (x) of HPW (x= 0, 0.5, 1, 2, 3, 5, 10 wt. %) were prepared using the sol-gel process. These catalysts were characterized by x-ray diffraction (XRD), energy dispersive x-ray spectroscopy (EDX), temperature-programmed reduction (TPR), nitrogen adsorption measurements (BET method) and Fourier transform infrared spectroscopy (FTIR). The catalytic tests were performed at a temperature of 250-425 °C in a reactor coupled with gas chromatograph (GC) for direct in situ analysis of the reaction products. The results obtained showed that addition of HPW up to 2 wt % leads to an increase in the efficiency of the catalyst from 10% to 31%, as measured by the rate of conversion of CO. However, further increase in the amount of HPW above 2 wt. % leads to a decrease in activity of the catalyst. A qualitative model based on the formation of amorphous Ni-phosphotungstate salt is proposed to explain this behaviour of the catalyst. In a second part of this study, the amount of HPW (2 wt. %) and temperature (425 °C) were fixed and nitrogenate d silanes with amine and nitrile functional groups were added to the catalyst to evaluate the role of these ormosils as dispersing agents for metallic cations in the hybrid precursor material as well as metallic nickel in the final catalyst. The catalyst derived from precursor containing ormosils with ammine functional groups (3-Aminopropyltriethoxysilane) showed better catalytic activity than those containing nitrile functional groups (4-(Triethoxysilyl)butyronitrile). However, the catalytic activity of the catalysts obtained using ormosils bearing nitrogenated silanes was lower than xerogels catalyst prepared without addition of these silanes. Although, the catalysts prepared using the ormosils bearing nitrogenated silanes showed higher stability than NS-x catalyst.

Hydrogen is a by-product of the gasification process and it is environmentally friendly with respect to pollution and emission issues when it is derived from a CO2-neutral resource such as biomass. It is an energy carrier fuel and has flexibility to convert efficiently to other energy forms to be used in different energy applications like fuel cells. The proposed research presents literature on previous gasification studies regarding hydrogen production from biomass and updates the obtained results. The main objectives of the thesis are: a) to study hydrogen production via steam biomass (sawdust) gasification; b) to evaluate the produced hydrogen by performing comprehensive analysis by using thermodynamic, exergoeconomic and optimization analyses. Despite details specific to the gasifier, in general, there is a special need to theoretically address the gasifier that gasifies biomass to produce hydrogen. This further study of gasification aspects presents a comprehensive performance assessment through energy and exergy analyses, provides results of the optimization studies on minimizing hydrogen production costs, and provides a thermo-economic analysis for the proposed systems (Systems I, II and III). This thesis also includes the results from the performed study that aims to investigate theoretical hydrogen production from biomass (sawdust) via gasification technology. Results from the performed parametric study show that the gasification ratio increases from 70 to 107 gH2 per kg of sawdust. In the gasification temperature studied, system II has the highest energy efficiency that considers electricity production where it increases from 72 % to 82 % and has the lowest energy efficiency that considers hydrogen yield where it increases from 45 % to 55 %. Also, it has the lowest hydrogen cost of 0.103 $/kW-h. The optimization results show that the optimum gasification temperatures for System I, System II and System III are 1139 K, 1245 K and 1205 K, respectively. / UOIT

Aqueous-phase reforming (APR) is reported for the first time for the production of H2 from actual biomass. The experiments are carried out in batch using a 100mL Parr microreactor heated to 225C. In this one-pot, two-step process, acid hydrolysis is used to break down the polymeric constituents of biomass to smaller soluble molecules and these species are reformed using a Pt/Al2O3 catalyst. The experiments show that increasing the acid concentration from 1% to 5% causes more than a twelve-fold increase in H2 concentration, with hydrogen a minor product accounting for 18% of the non-condensable gas phase and CO2 as the major product. In the presence of the Pt/Al2O3 reforming catalyst, both the selectivity and yield of hydrogen in the gas phase increase. This is accompanied by a noticeable decrease in carbon monoxide production. Comparison with other feeds such as glucose, wastepaper and ethylene glycol showed that the amount of hydrogen produced from biomass is of a comparable magnitude per gram of feed, although biomass yields more hydrogen per gram of carbohydrate than either glucose or wastepaper. Baseline experiments with only the catalysts in the absence of any biomass show no increase in the reactor system pressure when only water and helium are present, indicating that the observed hydrogen produced is sourced form the biomass.

La production de l'hydrogène à partir de biomasse est actuellement à l'étude mais la méthode de valorisation du biogaz (mélange H2/CO2) par réactions catalytiques, autres que la simple combustion, n'a pas encore été retenue. Par conséquent, le principal objectif de ce travail est d'explorer les autres voies. L'effet du CO2 sur le système catalytique est mal connu et seulement un effet négatif sur la dissociation de l'hydrogène a été mentionné. L'hydrogénation du toluène sur un catalyseur Pt a d'abord été étudiée sans CO2 pour suivre son comportement et éventuellement sa perte d'activité. En présence de CO2, l'inactivité complète du catalyseur pour l'hydrogénation du toluène a été mis en évidence. La modification de la surface du catalyseur par le CO2 est quantifiée par DRIFT et un mécanisme à deux sites a été montré. La réaction de Reverse Water Gas Shift produisant du CO se trouve être la principale cause de la désactivation de la surface de catalyseur avec le CO2. Donc la compétition d'adsorption entre le CO et des acides carboxyliques a été mise à profit pour favoriser sélectivement la conversion des acides. Pour l'alumine, elle est polluée par des carbonates complexes venant du CO2. La silice étant aussi connue pour promouvoir la décomposition, ces supports ont été rejetés. L'oxyde de titane a été utilisé pour catalyser une autre gamme de produits. Sur ce catalyseur, le changement de sélectivité entre le RWGS et la conversion de l'acide a été observé. Quant à l'oxyde de fer (catalyseur moins actif), il n'est pas capable de produire du CO à partir du CO2. La chimie de surface de l'oxyde de fer joue un rôle important sur la sélectivité du produit parmi les cétones et les aldéhydes. Un mécanisme à deux sites peut réutiliser pour l'oxyde de fer, montrant qu'un fonctionnement stable peut être trouvé si la réduction par l'hydrogène est continue. Si l'oxyde de fer est totalement oxydé par le CO2, produit de réaction, la production des cétones cesse. Énergiquement, le procédé de production d'acétone peut être autosuffisant et l'acétone peut être utilisée comme une molécule de stockage d'énergie. Le procédé va aussi compenser le nouveau procédé de production de phénol qui ne produit pas l'acétone.

An investigation was undertaken to determine the feasibility of increasing the hydrogen production rate by coupling the water gas shift (WGS) process to the hybrid sulphur process (HyS). This investigation also involved the technical and economical analysis of the water gas shift and the H2 separation by means of Pressure swing adsorption (PSA) process. A technical analysis of the water gas shift reaction was determined under the operating conditions selected on the basis of some information available in the literature. The high temperature system (HTS) and low temperature system (LTS) reactors were assumed to be operated at temperatures of 350ºC and 200ºC, respectively. The operating pressure for both reactors was assumed to be 30 atmospheres. The H2 production rate of the partial oxidation (POX) and the WGS processes was 242T/D, which is approximately two times the amount produced by the HyS process alone. The PSA was used for the purification process leading to a hydrogen product with a purity of 99.99%. From the total H2 produced by the POX and the WGS processes only 90 percent of H2 is recovered in the PSA. The unrecovered H2 leaves the PSA as a purge gas together with CO2 and traces of CH4, CO, and saturated H2O. The estimated capital cost of the WGS plant with PSA is about US$50 million. The production cost is highly dependent on the cost of all of the required raw materials and utilities involved. The production cost obtained was US $1.41/kg H2 based on the input cost of synthesis gas as produced by the POX process. In this case the production cost of synthesis gas based on US $6/GJ for natural gas and US $0/Ton for oxygen was estimated to be US $0.154/kg. By increasing the oxygen and natural gas cost, the corresponding increase in synthesis gas has resulted in an increase in H2 production cost of US $1.84/kg. / Thesis (M.Sc. (Chemical Engineering))--North-West University, Potchefstroom Campus, 2006.

An investigation was undertaken to determine the feasibility of increasing the hydrogen production rate by coupling the water gas shift (WGS) process to the hybrid sulphur process (HyS). This investigation also involved the technical and economical analysis of the water gas shift and the H2 separation by means of Pressure swing adsorption (PSA) process. A technical analysis of the water gas shift reaction was determined under the operating conditions selected on the basis of some information available in the literature. The high temperature system (HTS) and low temperature system (LTS) reactors were assumed to be operated at temperatures of 350°C and 200°C, respectively. The operating pressure for both reactors was assumed to be 30 atmospheres. The H2 production rate of the partial oxidation (POX) and the WGS processes was 242T/D, which is approximately two times the amount produced by the HyS process alone. The PSA was used for the purification process leading to a hydrogen product with a purity of 99.99%. From the total H2 produced by the POX and the WGS processes only 90 percent of H2 is recovered in the PSA. The unrecovered H2 leaves the PSA as a purge gas together with C02 and traces of CH4, CO, and saturated H20. The estimated capital cost of the WGS plant with PSA is about US$50 million. The production cost is highly dependent on the cost of all of the required raw materials and utilities involved. The production cost obtained was US $1.41/kg H2 based on the input cost of synthesis gas as produced by the POX process. In this case the production cost of synthesis gas based on US $6/GJ for natural gas and US $0/Ton for oxygen was estimated to be US $0.154/kg. By increasing the oxygen and natural gas cost, the corresponding increase in synthesis gas has resulted in an increase in H2 production cost of US $1.84/kg. / Thesis (M.Sc. (Nuclear Engineering))--North-West University, Potchefstroom Campus, 2009.

An investigation was undertaken to determine the feasibility of increasing the hydrogen production rate by coupling the water gas shift (WGS) process to the hybrid sulphur process (HyS). This investigation also involved the technical and economical analysis of the water gas shift and the H2 separation by means of Pressure swing adsorption (PSA) process. A technical analysis of the water gas shift reaction was determined under the operating conditions selected on the basis of some information available in the literature. The high temperature system (HTS) and low temperature system (LTS) reactors were assumed to be operated at temperatures of 350°C and 200°C, respectively. The operating pressure for both reactors was assumed to be 30 atmospheres. The H2 production rate of the partial oxidation (POX) and the WGS processes was 242T/D, which is approximately two times the amount produced by the HyS process alone. The PSA was used for the purification process leading to a hydrogen product with a purity of 99.99%. From the total H2 produced by the POX and the WGS processes only 90 percent of H2 is recovered in the PSA. The unrecovered H2 leaves the PSA as a purge gas together with C02 and traces of CH4, CO, and saturated H20. The estimated capital cost of the WGS plant with PSA is about US$50 million. The production cost is highly dependent on the cost of all of the required raw materials and utilities involved. The production cost obtained was US $1.41/kg H2 based on the input cost of synthesis gas as produced by the POX process. In this case the production cost of synthesis gas based on US $6/GJ for natural gas and US $0/Ton for oxygen was estimated to be US $0.154/kg. By increasing the oxygen and natural gas cost, the corresponding increase in synthesis gas has resulted in an increase in H2 production cost of US $1.84/kg. / Thesis (M.Sc. (Nuclear Engineering))--North-West University, Potchefstroom Campus, 2009.

Esta dissertação mostra um estudo preliminar da preparação de precursores catalíticos a base de níquel (II) e de sua conversão em catalisadores de xerogéis contendo níquel (NS), bem como o estudo da sua atividade catalítica na reação de deslocamento gás-água. Esta reação foi escolhida como reação modelo para avaliar a atividade catalítica, em especial frente a adição do ácido fosfotungstico (HPW) como promotor catalítico e de organosilanos como agentes promotores da dispersão do Ni. Foram preparados catalisadores NS e NS-x (x = 0,5; 1; 2; 3; 5 e 10% em massa de HPW) via processo sol-gel. A caracterização estrutural foi realizada utilizando-se as técnicas de Energia Dispersiva de Raios X, Difratometria de Raios X, Redução a Temperatura Programada, Fisissorção de Nitrogênio, Espectroscopia de Absorção de Raios X e Espectroscopia de Absorção na Região do Infravermelho. Os testes catalíticos foram realizados no Laboratório de Catálise Heterogênea do IQSC/USP numa temperatura de 250-425 °C, em uma lin ha de reação acoplada a um cromatógrafo a gás para análises in situ dos produtos reacionais gasosos. Os resultados obtidos da primeira parte mostraram que a adição do HPW até 2% em massa de precursor catalítico leva a uma melhora gradual na atividade catalítica de 10 a 31 % medido pela taxa de conversão do CO. Contudo acima de 2% ocorre uma queda de atividade catalítica resultando num comportamento global da conversão de CO do tipo gaussiano com o máximo em 2%. Para explicar este comportamento um modelo qualitativo é proposto baseado na formação de fosfotungstato de níquel amorfo acima de 2%. Na segunda parte do trabalho, a concentração de HPW foi fixada em 2% e a temperatura de reação em 425 °C e foram adicionados organosilanos nitrogenados (amino e nitrila) para avaliar a sua capacidade de funcionar como agentes de dispersão do cátion metálico no precursor híbrido (Ormosil) e do metal no catalisador. O catalisador proveniente do precursor contendo grupo amina possui maior atividade catalítica que aquele contendo nitrila, porém ambos possuem menor atividade que o xerogel catalítico obtido de precursores sem grupos nitrogenados. Contudo, os catalisadores preparados a partir de Ormosils mostravam-se estáveis ao longo do tempo da reação estudada quando comparados com os xerogeis NS-x. / This dissertation describes the preparation of Ni (II)-based catalyst precursor material and its subsequent conversion to Ni-based xerogels catalyst as well as the catalytic activity of the resultant catalyst in water-gas shift reaction. The water-gas shift reaction was selected as a model reaction for the evaluation of catalytic activity of the prepared catalysts. The effect of addition of phosphotungstic acid (HPW) as an activity promoting agent and organosilane as dispersing agents of Ni was also studied. For this purpose, Ni-based catalyst (NS-x) containing various amounts (x) of HPW (x= 0, 0.5, 1, 2, 3, 5, 10 wt. %) were prepared using the sol-gel process. These catalysts were characterized by x-ray diffraction (XRD), energy dispersive x-ray spectroscopy (EDX), temperature-programmed reduction (TPR), nitrogen adsorption measurements (BET method) and Fourier transform infrared spectroscopy (FTIR). The catalytic tests were performed at a temperature of 250-425 °C in a reactor coupled with gas chromatograph (GC) for direct in situ analysis of the reaction products. The results obtained showed that addition of HPW up to 2 wt % leads to an increase in the efficiency of the catalyst from 10% to 31%, as measured by the rate of conversion of CO. However, further increase in the amount of HPW above 2 wt. % leads to a decrease in activity of the catalyst. A qualitative model based on the formation of amorphous Ni-phosphotungstate salt is proposed to explain this behaviour of the catalyst. In a second part of this study, the amount of HPW (2 wt. %) and temperature (425 °C) were fixed and nitrogenate d silanes with amine and nitrile functional groups were added to the catalyst to evaluate the role of these ormosils as dispersing agents for metallic cations in the hybrid precursor material as well as metallic nickel in the final catalyst. The catalyst derived from precursor containing ormosils with ammine functional groups (3-Aminopropyltriethoxysilane) showed better catalytic activity than those containing nitrile functional groups (4-(Triethoxysilyl)butyronitrile). However, the catalytic activity of the catalysts obtained using ormosils bearing nitrogenated silanes was lower than xerogels catalyst prepared without addition of these silanes. Although, the catalysts prepared using the ormosils bearing nitrogenated silanes showed higher stability than NS-x catalyst.

Orientador: Daniela Zanchet / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Química / Made available in DSpace on 2018-08-26T07:36:24Z (GMT). No. of bitstreams: 1 Kokumai_TathianaMidori_M.pdf: 2185484 bytes, checksum: f809cfde78398806bc98554749cf01c8 (MD5) Previous issue date: 2014 / Resumo: Nanobastões de céria (CeO2) funcionalizados com grupos amino foram utilizados como suporte em catalisadores de cobre para a reação de deslocamento gás-água (WGS). A funcionalização da superfície do óxido foi realizada visando uma melhor dispersão da fase metálica no suporte, através da interação entre o grupo amino e o precursor Cu2+, com a posterior correlação entre esta modificação e a atividade do catalisador. Utilizou-se o método hidrotérmico para a síntese dos nanobastões, que foram posteriormente funcionalizados com 3-(aminopropil)trimetoxisilano. A adição do precursor Cu2+ ao suporte foi feita via impregnação, seguida de calcinação e redução (ativação do catalisador), etapa na qual se formaram as nanopartículas metálicas (Cu0) suportadas. Comparando os catalisadores com suporte de céria pura e de céria funcionalizada, observou-se que de fato a funcionalização resultou na maior dispersão do Cu2+ na superfície. No entanto, ela causou a menor dispersão do metal (Cu0) após a redução, a diminuição da redutibilidade da céria superficial, a fragmentação dos bastões e o menor desempenho catalítico frente à reação de WGS. Visando a compreensão destes sistemas, verificou-se que a calcinação após a adição de Cu2+ na amostra funcionalizada formou uma camada de SiO2 na superfície da céria, o que diminui a atividade por reduzir as interações Cu-CeO2 (formação de Cu-O-Si), corroborando a grande influência desta interface no desempenho destes catalisadores. Além disso, a menor dispersão de Cu0 na superfície funcionalizada após a redução demonstrou a importância da céria também na estabilização da fase metálica. Desta maneira, a funcionalização da superfície se mostrou uma abordagem interessante no que se refere à dispersão do precursor metálico no suporte / Abstract: Amino functionalized ceria nanorods were explored as support on copper catalysts for the water-gas shift (WGS) reaction. The purpose of the design of a functionalized oxide surface was to obtain a better metal phase dispersion on the support provided by amino-Cu2+ interaction, in addition to further correlation between this modification and the catalyst activity. The hydrothermal method was used to synthetize the nanorods, which were subsequently functionalized with 3-(aminopropyl)trimethoxysilane. The Cu2+ precursor was added to the support by impregnation, followed by calcination and reduction (catalyst activation), when the supported metallic (Cu0) nanoparticles were formed. By comparison of the catalysts obtained with pure ceria and functionalized ceria supports it was observed that the functionalization indeed caused a greater Cu2+ dispersion on the oxide surface. However, it gave rise to a lower metal dispersion (Cu0) after reduction step, along with the decrease of surface ceria reducibility, nanorods fragmentation and inferior catalytic performance towards WGS reaction. In order to understand these systems, it was confirmed that the calcination step (after Cu2+ addition) on functionalized sample created a SiO2 layer above ceria surface, therefore lowering the activity due to the decrease of Cu-CeO2 interactions (formation of Cu-O-Si), which corroborated the great influence of Cu-CeO2 interface on the activity. Also, the lower Cu0 dispersion on the functionalized surface after reduction showed the importance of ceria on the metallic phase stabilization. Hence, the surface functionalization demonstrated to be an interesting approach to the dispersion of metal precursor on the catalyst support / Mestrado / Quimica Inorganica / Mestra em Química

Le projet Européen UNIfHY a vu le jour dans une optique de production d’hydrogène à partir de biomasse pour le remplacement des énergies fossiles. La purification des gaz produits par la gazéification de la biomasse permet l’obtention d’hydrogène pur pour une utilisation dans les piles à combustible. Cette thèse s’inscrit dans ce projet avec pour but le développement de catalyseurs Fe/CeO2 et Cu/CeO2 déposés sur des supports de mousse céramique pour la réaction de conversion du gaz à l’eau à haute et basse températures, de manière à augmenter la production d’hydrogène et diminuer la perte de charge dans le système. Les principaux objectifs de la thèse sont la synthèse et les caractérisations des catalyseurs à base de fer et de cuivre, l’optimisation des conditions réactionnelles dans la limite du cadre fixé par le projet, la modélisation cinétique en présence des catalyseurs Fe/CeO2 et Cu/CeO2 et la transposition à grande échelle des catalyseurs pour une utilisation en réacteur pilote. / The UNIfHY European project was launched in an optic of producing hydrogen from biomass to replace fossil fuels. Purification of gases produced by biomass gasification allows obtaining pure hydrogen which can be used in fuel cells. This thesis takes part in this project with the development of Fe/CeO2 and Cu/CeO2 catalysts deposited on ceramic foam supports for high temperature and low temperature water gas shift reaction to increase the production of hydrogen and decrease the pressure drop in the system. The main objectives of this thesis are the synthesis and characterizations of iron and copper based catalysts, the optimization of reaction conditions within the limits of the framework set by the project, the kinetic modeling of the reaction in the presence of Fe/CeO2 and Cu/CeO2 catalysts and the scale-up of catalysts to use them in a pilot reactor.