Dissertations / Theses on the topic 'Cu-Ni catalysts'

CuNi nanoparticles were synthesized using a new polyol synthesis method. Three different CuxNi1-x catalysts were synthesized where x = 20, 50 and 80. The nanoparticles were deposited on carbon, C, gamma-alumina, γ-Al2O3, yttria-stabilized zirconia, YSZ, and samariumdoped ceria, SDC. Each set of catalysts was tested using the Reverse Water Gas Shift, RWGS, reaction under atmospheric pressure and at temperatures ranging from 400°C-700°C. The experiments were repeated 3 times to ensure stability and reproducibility. Platinum nanoparticles were also deposited on the same supports and tested for the RWGS reaction at the same conditions. The CuNi nanoparticles were characterized using a variety of different techniques. Xray diffraction, XRD, measurements demonstrate the resence of two CuNi solid solutions: one Cu rich solid solution, and the other a Ni rich solid solution. X-ray photo electron spectroscopy, XPS, measurements show Cu enrichment on all catalytic surfaces. Scanning electron microscopy, SEM, measurements show CuNi nanoparticles ranging in size from 4 nm to 100 nm. Some agglomeration was observed. SDC showed the best yield with all catalysts. Furthermore, high oxygen vacancy content was shown to increase yield of CO for the RWGS reaction. Cu50Ni50/SDC shows the combination of highest yield of CO and the best stability among CuNi catalysts. It also has similar yields (39.8%) as Pt/SDC at 700°C, which achieved the equilibrium yield at that temperature (43.9%). The catalyst was stable for 48 hours when exposed to high temperatures (600-700°C). There was no CH4 observed during any of the experiments when the partial pressure of the reactant gases was fed stoichiometrically. Partial pressure variation experiments demonstrated the presence of CH4 when the partial pressure of hydrogen was increased to twice the value of the partial pressure of CO2.

Dissertation (Ph. D.)--University of Akron, Dept. of Chemical Engineering, 2007.<br>"December, 2007." Title from electronic dissertation title page (viewed 03/12/2008) Advisor, Steven S. C. Chuang; Committee members, Lu-Kwang Ju, Edward Evans, W. B. Arbuckle, Stephen Z. D. Cheng; Department Chair, Lu-Kwang Ju; Dean of the College, George K. Haritos; Dean of the Graduate School, George R. Newkome. Includes bibliographical references.

Ce travail porte sur la préparation et la caractérisation de catalyseurs bimétalliques Cu-Zn, Ni-Zn et Fe-Zn supportés sur TiO2 avec des rapports atomiques variables et sur l'étude de leurs propriétés catalytiques pour l'hydrogénation sélective d'hydrocarbures polyinsaturés. Les méthodes de co-dépôt-précipitation à l'urée (DPu) et co-dépôt-précipitation à pH fixe (DP8) ont été utilisées pour la préparation des matériaux. Les ions métalliques se déposent séquentiellement sur la surface de TiO2 (selon la séquence CuII &lt; ZnII ?FeII <br>This work investigates the preparation and characterization of titania-supported non-noble bimetallic Cu-Zn, Ni-Zn and Fe-Zn catalysts with various atomic ratios and their catalytic properties for the selective hydrogenation of polyunsaturated hydrocarbons. Co-deposition-precipitation with urea (DPu) and co-deposition-precipitation at fixed pH (DP8) methods were employed for the samples preparation. The metal ions were sequentially deposited onto the TiO2 surface (the sequence of pH for ions deposition being CuII &lt; ZnII ≈FeII &lt; NiII) during the DPu, while they were simultaneously deposited using DP8 method. After sample reduction at proper temperature (350 °C for Cu-Zn, 450 °C for Ni-Zn and 500 °C for Fe-Zn), XRD and STEM-HAADF coupled with EDS showed that bimetallic nanoparticles were formed in Cu-Zn/TiO2 (Cu3Zn1 or Cu0.9Zn0.1 alloy) and Ni-Zn systems (Ni1Zn1 or Ni4Zn1 alloy) with average particle size smaller than 5 nm. Only metallic Fe was detected by XRD in Fe-Zn/TiO2. Zn is inactive for butadiene selective hydrogenation, and acts as a modifier of the monometallic catalysts whose activity follows the sequence: Cu &lt; Fe &lt; Ni. The addition of Zn slightly decreases the activity and influences the selectivity to butenes, but provides much more stable catalysts. The higher stability of the bimetallic catalysts was ascribed to the formation of lower amount of carbonaceous species during the reaction, resulting from the change in the size of the active metal surface ensembles by alloying with Zn

La production d'additifs pour les carburants, d’indices d'octane élevés, à partir des molécules biosourcées telles que le 5-hydroxyméthylfurfural (HMF) est le sujet de nombreuses études. Les catalyseurs à base de Pt, de Pd et de Ru sont décrits comme particulièrement actifs dans la réaction de conversion du HMF en 2,5-diméthylfurane (DMF) et en 2,5-diméthyltétrahydrofurane (DMTHF). Cependant leur substitution dans les formulations catalytiques est souhaitable compte tenu de leur coût élevé et de leur faible disponibilité. Les éléments de substitution peuvent être certains métaux de transition (par exemple Cu ou Ni), plus abondants, mais généralement moins actifs. Mes travaux de recherche ont donc portés sur la préparation de catalyseurs, à base de métaux de transition, actifs et sélectifs pour l'hydrogénation du HMF en des molécules pouvant être incorporées dans les carburants. Les phases actives étudiées au cours de mon doctorat reposent sur les métaux de transition Ni et Cu. Ces phases actives ont été supportées sur des silices mésoporeuses de type SBA-15. L'étude est divisée en deux parties distinctes, en fonction du métal étudié. La première partie du doctorat présente les résultats obtenus avec des catalyseurs monométalliques Ni supportés. Dans un premier temps, l'optimisation des paramètres de réaction pour l'hydroconversion sélective du HMF en DMF et en DMTHF a été réalisée en utilisant un catalyseur préparé par la méthode d'imprégnation à humidité naissante d’une solution du précurseur nitrate (Chapitre 3). Les paramètres de réaction optimisés incluent la température de réaction, la pression de dihydrogène, le rapport molaire HMF/Ni et le temps de réaction. Une étude cinétique préliminaire a également été réalisée. L’effet de la dispersion et de la taille des particules métalliques de Ni sur les performances catalytiques des catalyseurs Ni/SBA-15 a été étudié sur des matériaux préparés par la méthode d’infiltration à l'état fondu des précurseurs nitrates (Chapitre 4). Le niveau de dispersion du nickel a été modifié en utilisant des supports SBA-15 contenant des porosités d’interconnexion différentes et obtenues à différentes températures de synthèse. Les résultats montent que le catalyseur Ni/SBA-15, préparé par la méthode simple IWI, permet d’atteindre des rendements élevés en DMF et DMTHF dans des conditions réactionnelles optimales. Le niveau de dispersion du Ni, tel qu’observé à partir des matériaux obtenus par infiltration des sels fondus, a quant à lui un effet significatif sur l'activité catalytique du catalyseur. La deuxième partie de mes travaux de recherche porte sur les propriétés catalytiques des catalyseurs monométalliques à base de Cu/SBA-15 préparés par différentes méthodes, et présentant des états de division de la phase Cu différents (Chapitre 5). Les modes de synthèse appliqués incluent la méthode d’imprégnation à humidité naissante (IWI), la méthode d'autocombustion in situ (ISAC) et la méthode de déposition par précipitation (DP). La première partie de l’étude a donc portée sur l'optimisation des conditions de réaction pour l'hydroconversion sélective du HMF en DMF (avec le catalyseur Cu/SBA-15 préparé par la méthode ISAC). Les paramètres de réaction optimisés, comme dans le cadre de l’étude avec Ni/SBA-15, ont été la température de réaction, la pression de dihydrogène, le rapport molaire HMF/Cu et le temps de réaction. La réutilisation du catalyseur a également été étudiée, et une étude cinétique de la transformation du HMF sur Cu menée. Cette partie démontre que l’activité du Cu pour la conversion sélective du HMF en DMF dépend principalement de l’état de dispersion du Cu. L'utilisation de la méthode DP a conduit à un catalyseur Cu/SBA-15 hautement divisé, ce qui a permis d’atteindre des rendements élevs en DMF<br>The production of fuel additives, having high octane numbers, from biosourced molecules such as 5-hydroxymethylfurfural (HMF), is the subject of many studies. The Pt, Pd and Ru-based catalysts are described as particularly active in the conversion reaction of HMF to 2,5-dimethylfuran (DMF) and to 2,5-dimethyltetrahydrofuran (DMTHF). However, their substitutions in the catalytic formulations are desirable in view of their high cost and low availability. The substitution elements can be transition metals (for example Cu or Ni), which are more abundant, but generally less active. My research has focused on the preparation of catalysts, based on transition metals, active and selective for the hydrogenation of HMF into molecules that can be incorporated into fuels. The active phases studied during my Ph.D. are based on Ni and Cu transition metals. These active phases were supported on mesoporous silica of SBA-15 type. The study is divided into two distinct parts, depending on the metal studied.The first part of the Ph.D. presents the results obtained with Ni supported monometallic catalysts. In a first step, the optimization of the reaction parameters for the selective hydroconversion of HMF to DMF and DMTHF was carried out using a catalyst prepared by the incipient wetness impregnation (IWI) of the nitrate precursor solution (Chapter 3). Optimized reaction parameters include reaction temperature, dihydrogen pressure, HMF/Ni molar ratio, and reaction time. A preliminary kinetic study was also performed. The effect of the dispersion and size of Ni metal particles on the catalytic performance of Ni/SBA-15 catalysts was studied on materials prepared by the melt infiltration (MI) method of nitrate precursors (Chapter 4). The level of dispersion of the nickel was modified using SBA-15 supports containing different interconnection porosities, obtained at different synthesis temperatures. The results show that the Ni/SBA-15 catalyst, prepared by the simple IWI method, achieves high yields of DMF and DMTHF under optimal reaction conditions. The level of Ni dispersion, as observed from the materials obtained by infiltration of molten salts, has a significant effect on the catalytic activity of the catalyst.The second part of my research focuses on the catalytic properties of Cu/SBA-15 monometallic catalysts prepared by different methods, and having different Cu phase division degree (Chapter 5). The methods of preparation applied include the IWI method, the in situ autocombustion method (ISAC) and the deposition-precipitation method (DP). The first part of the study therefore focused on the optimization of the reaction conditions for the selective hydroconversion of HMF to DMF (over the Cu/SBA-15 catalyst prepared by the ISAC method). Optimized reaction parameters, as for Ni/SBA-15, were reaction temperature, hydrogen pressure, HMF/Cu molar ratio, and reaction time. The reuse of the catalyst was also studied, and a kinetic study of the transformation of HMF on Cu/SBA-15 conducted. This part demonstrates that the activity of Cu for the selective conversion of HMF to DMF depends mainly on the state of dispersion of Cu. The use of the DP method led to a highly divided Cu/SBA-15 catalyst, which made it possible to achieve high yields of DMF

Ce travail porte sur la préparation et la caractérisation de catalyseurs bimétalliques Cu-Zn, Ni-Zn et Fe-Zn supportés sur TiO2 avec des rapports atomiques variables et sur l'étude de leurs propriétés catalytiques pour l'hydrogénation sélective d'hydrocarbures polyinsaturés. Les méthodes de co-dépôt-précipitation à l'urée (DPu) et co-dépôt-précipitation à pH fixe (DP8) ont été utilisées pour la préparation des matériaux. Les ions métalliques se déposent séquentiellement sur la surface de TiO2 (selon la séquence CuII &lt; ZnII ?FeII <br>This work investigates the preparation and characterization of titania-supported non-noble bimetallic Cu-Zn, Ni-Zn and Fe-Zn catalysts with various atomic ratios and their catalytic properties for the selective hydrogenation of polyunsaturated hydrocarbons. Co-deposition-precipitation with urea (DPu) and co-deposition-precipitation at fixed pH (DP8) methods were employed for the samples preparation. The metal ions were sequentially deposited onto the TiO2 surface (the sequence of pH for ions deposition being CuII &lt; ZnII ≈FeII &lt; NiII) during the DPu, while they were simultaneously deposited using DP8 method. After sample reduction at proper temperature (350 °C for Cu-Zn, 450 °C for Ni-Zn and 500 °C for Fe-Zn), XRD and STEM-HAADF coupled with EDS showed that bimetallic nanoparticles were formed in Cu-Zn/TiO2 (Cu3Zn1 or Cu0.9Zn0.1 alloy) and Ni-Zn systems (Ni1Zn1 or Ni4Zn1 alloy) with average particle size smaller than 5 nm. Only metallic Fe was detected by XRD in Fe-Zn/TiO2. Zn is inactive for butadiene selective hydrogenation, and acts as a modifier of the monometallic catalysts whose activity follows the sequence: Cu &lt; Fe &lt; Ni. The addition of Zn slightly decreases the activity and influences the selectivity to butenes, but provides much more stable catalysts. The higher stability of the bimetallic catalysts was ascribed to the formation of lower amount of carbonaceous species during the reaction, resulting from the change in the size of the active metal surface ensembles by alloying with Zn

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No. of bitstreams: 2 Dissertação - Jarbas Almeida de Melo - 2018.pdf: 7287109 bytes, checksum: 8e33ba1a3ef2d679e03ecdb4e368b53c (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2018-09-28<br>Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES<br>In this work the synthesis of catalysts was carried out with the objective of H2 production from gasification of ethanol in medium containing water under supercritical conditions. Based on reports from the literature, Cu, Ni and Mg were selected as components for the active phase, alumina (Al2O3) as catalysts support. The catalysts were prepared from aqueous solutions of nitrate salts precursors of Cu, Ni and Mg. The catalysts were characterized by X-ray fluorescence (FRX), scanning electron microscopy, thermogravimetric and thermal differential analysis (TG/ATD), X-ray diffraction (DRX) and textural analysis by N2 adsorption / desorption isotherms at -196 ° C. The TG/ATD analysis indicated that the calcination of the catalytic precursors was sufficient for the removal of water and decomposition of the nitrates of the metal salts precursors of the active phase. In the FRX analysis, the increase in the concentration of the metals in relation to the nominal values after the synthesis of the catalysts was characterized, with an increase of 20 to 40% depending on the metal due to the loss of water from the alumina support. The FRX analysis of the catalysts used in the catalytic tests shows that there was no significant leaching during the gasification process. DRX analysis have characteristic results that the metals are in amorphous form or dispersed in the form of small crystallites. Textural analysis of N2 adsorption / desorption isotherms indicated a reduction of approximately 60% in the specific surface area between the alumina and the calcined alumina and the specific area values between the alumina and the metal catalysts were kept close. The catalytic tests were performed at a pressure of 25 MPa and at temperatures of 400 to 650 ° C. A 10/1 molar water / ethanol solution was fed. In the catalytic tests H2, CH4, CO, CO2, C2H4, C2H6, C2H4O were obtained. The highest ethanol conversions were obtained at the temperature of 650 ° C for the catalysts NiO/Al2O3 and NiO-MgO/Al2O3, both 81%. The highest yield was 0.41 mol H2 / mol ethanol fed to the NiO / Al2O3 catalyst, at a temperature of 600 ° C. The highest selectivity at the temperature of 600 ° C was 39%, obtained by the NiO/Al2O3 catalyst.<br>Neste trabalho foi realizada a síntese de catalisadores com o objetivo da produção de H2 a partir da gaseificação de etanol em meio contendo água em condições supercríticas. A partir de relatos da literatura, foram selecionados Cu, Ni e Mg como componentes para a fase ativa e a alumina (Al2O3) como suporte dos catalisadores. Os catalisadores foram preparados a partir de soluções aquosas de sais de nitrato precursores de Cu, Ni e Mg. Os catalisadores foram caracterizados por fluorescência de raios X (FRX), microscopia eletrônica de varredura (MEV), análises termogravimétrica e térmica diferencial simultânea (TG/ATD), difração de raios X (DRX) e análise textural por isotermas de adsorção/dessorção de N2 a -196°C. As análises de TG/ATD indicaram que a calcinação dos precursores catalíticos foi suficiente para a remoção da água e decomposição dos nitratos dos sais metálicos precursores da fase ativa. Nas análises de FRX ficou caracterizado o aumento da concentração dos metais em relação aos valores nominais, após a síntese dos catalisadores, com acréscimo de 20 a 40 % dependendo do metal, devido à perda de água do suporte de alumina. As análises FRX dos catalisadores utiilzados nos testes catalíticos mostraram que não houve lixiviação considerável durante o processo de gaseificação. Análises de DRX apresentaram resultados característicos de que os metais se encontram na forma amorfa ou dispersos na forma de pequenos cristalitos. Os resultados foram coerentes com as imagens de microscopia eletrônica de varredura. Análises textural por isotermas de adsorção/dessorção de N2 indicaram uma redução de aproximadamente 60% na área superficial específica entre a alumina e a alumina calcinada e mantiveram-se próximos os valores de área específica entre a alumina e os catalisadores metálicos. Os testes catalíticos foram realizados a uma pressão de 25 MPa e nas temperaturas de 400 a 650 °C. Foi alimentada uma solução de água/etanol na razão de 10/1 molar. Nos testes catalíticos foram obtidos H2, CH4, CO, CO2, C2H4, C2H6, C2H4O. As maiores conversões de etanol foram obtidas na temperatura de 650 °C para os catalisadores de NiO/Al2O3 e NiO-MgO/Al2O3, ambas 81 %. O maior rendimento obtido foi de 0,41 mol H2/mol etanol alimentado para o catalisador de NiO/ Al2O3, na temperatura de 600 °C. A maior seletividade na temperatura de 600 °C foi de 39 %, obtida pelo catalisador de NiO/Al2O3.

Le graphène est une couche de carbone d’une épaisseur atomique pour laquelle les atomes de carbone sont hybridés sp². Il possède diverses propriétés remarquables supérieures à celles des autres matériaux connus. Le dépôt chimique en phase vapeur (CVD) est une méthode prometteuse pour produire du graphène monocouche. Dans cette étude, du graphène monocouche a pu être synthétisé directement sur une feuille de Ni polycristallin par CVD sous pression atmosphérique à l'aide d'un refroidissement rapide. Par ailleurs, nous proposons une technique simple pour préparer du graphène monocouche homogène dont la croissance est réalisée simultanément sur deux feuilles de Cu et de Ni assemblés en bicouche métallique. L’application du refroidissement rapide induit la formation de Ni3C, qui permet de réutiliser la feuille de Ni jusqu'à 6 fois sans causer d’écart significatif de la qualité et l'uniformité du graphène produit. Ce travail a donc démontré avec succès que le coût moyen pour synthétiser une monocouche de graphène de haute qualité pouvait être réduit avec des procédés simples à mettre en œuvre<br>Graphene is a layer of sp2 hybridized carbon atoms with a thickness of only one atom. It possesses various magnificent properties that are not shared by other materials. To date, Chemical Vapor Deposition (CVD) is a promising method to produce wafer-scale graphene. From our study, monolayer graphene was grown directly on polycrystalline Ni foil under simple atmospheric pressure CVD with the assist of fast cooling. On the other hand, another facile technique was successful to grow uniform monolayer graphene simultaneously on both polycrystalline Ni and Cu foils using a Ni-Cu bilayer catalyst. The application of post-CVD fast cooling encourages the formation of Ni3C within the Ni foil, which subsequently enables the Ni foil to be reused again up to 6 cycles without causing a huge deviation. This work has successfully demonstrated a simple, novel and cost effective route to synthesize monolayer graphene with high quality

This thesis describes the synthesis, characterisation and application of artificial metalloenzymes as catalysts. The focus was on two mutants of SCP-2L (SCP-2L A100C and SCP-2L V83C) both of which possess a hydrophobic tunnel in which apolar substrates can accumulate. The crystal structure of SCP-2L A100C was determined and discussed with a special emphasis on its hydrophobic tunnel. The SCP-2L mutants were covalently modified at their unique cysteine with two different N-ligands (phenanthroline or dipicolylamine based) or three different phosphine ligands (all based on triphenylphosphine) in order to increase their binding capabilities towards metals. The metal binding capabilities of these artificial proteins towards different transition metals was determined. Phenanthroline modified SCP-2L was found to be a promising scaffold for Pd(II)-, Cu(II)-, Ni(II)- and Co(II)-enzymes while dipicolylamine-modified SCP-2L was found to be a promising scaffold for Pd(II)-enzymes. The rhodium binding capacity of two additional phosphine modified protein scaffolds was also investigated. Promising scaffolds for Rh(I)- and Ir(I)-enzymes were identified. Rh-enzymes of the phosphine modified proteins were tested in the aqueous-organic biphasic hydroformylation of linear long chain 1-alkenes and compared to the Rh/TPPTS reference system. Some Rh-enzymes were found to be several orders of magnitude more active than the model system while yielding comparable selectivities. The reason for this remarkable reactivity increase could not be fully elucidated but several potential modes of action could be excluded. Cu-, Co-, and Ni-enzymes of N-ligand modified SCP-2L A100C were tested in the asymmetric Diels-Alder reaction between cyclopentadiene and trans-azachalcone. A promising 29% ee for the exo-product was found for the phenanthroline modified protein in the presence of nickel. Further improvement of these catalyst systems by chemical means (e.g. optimisation of ligand structure) and bio-molecular tools (e.g. optimisation of protein environment) can lead to even more active and (enantio)selective catalysts in the future.

Orientador: Oswaldo Luiz Alves<br>Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Quimica<br>Made available in DSpace on 2018-08-13T13:21:45Z (GMT). No. of bitstreams: 1 Oliveira_FlavioHenrique_M.pdf: 1865644 bytes, checksum: f0716bfd25ded49ec69dd8796c111a00 (MD5) Previous issue date: 2009<br>Resumo: Sistemas ternários tipo hidrotalcita contendo metais de transição Ni, Fe e Cu tendo o ânion interlamelar o carbonato foram preparados através de um estudo sistemático de composição e parâmetros de síntese. Diferentes quantidades de Cu foram introduzidas na camada tipo brucita da hidrotalcita, sendo estas quantidades de 10, 20, 30, 40 e 50 % em relação a quantidade de Níquel. De acordo com difratogramas para baixas quantidades de cobre (10 e 20 %) a fase hidrotalcita apresentou-se pura, para maiores quantidades de cobre ocorreu segregação de fase a qual foi identificada como CuO. A preparação dos compostos ternários foi feita tendo como razão de metal II para metal III 2:1, essa razão entre os metais foi confirmada através de análises de ICP a qual demonstrou exata proporção entre os metais nas amostras. Análise térmica apresentaram um comportamento típico para hidrotalcitas, apresentando duas transições características a 170 °C e a 280 ºC. Devido à ocorrência de alta segregação de fases que ocorre na precipitação com estes metais, foram realizados experimentos com diferentes temperaturas de precipitação e os resultados preliminares indicam a formação de uma fase pura em baixas temperaturas. Compostos preparados com 30 % de Cu a temperatura ambiente apresenta segregação de fase o que não ocorre a temperaturas próximas a 0 ºC, temperaturas elevadas (60 °C) favorecem a formação de óxidos durante a precipitação. Portanto baixas temperaturas de precipitação resultam em fases puras de hidrotalcitas para concentrações de cobre intermediarias, como conseqüência é possível preparar amostras com altas concentrações de cobre na estrutura lamelar com a fase da hidrotalcita pura. Com estes metais de transição na estrutura lamelar este sistema pode vir a ser um bom precursor na formação de óxidos dos respectivos metais que constituem o composto, com a finalidade de ser utilizada em catálise<br>Abstract: Ternary systems of hydrotalcite-like compouds containing transition metals Ni, Fe and Cu and the interlayer anion the carbonate were prepared through a systematic study of composition and synthesis parameters. Different amounts of Cu were introduced into the layer hydrotalcite, and the figure of 10, 20, 30, 40 and 50% on the amount of Nickel. According to difratograms, for low quantities of copper (10 and 20%) the phase is pure hydrotalcite and for larger quantities of copper segregation occurred, which was identified as CuO. The preparation of ternary compound was made with the ratio of metal II to metal III 2:1, the ratio between the metals was confirmed through analysis of ICP which showed exact proportion between the metals in the samples. Thermal analysis showed a typical behavior for hydrotalcite, presenting features two transitions to 170 ° C and 280 C. Due to the high occurrence of segregation of phases in the precipitation that occurs with these metals, experiments were performed with different temperatures and precipitation and the preliminary results indicate the formation of a pure phase at low temperatures. Compounds prepared with 30% of Cu at room temperature shows segregation of the stage that does not occur at temperatures close to 0 º C, high temperature (60 C) favor the formation of oxides during the precipitation. In conclusion, low temperatures of precipitation result in phases of pure hydrotalcite for an intermediary concentration of copper, as a result, is possible to prepare samples with high concentrations of copper in the lamellar structure with pure phase of hydrotalcite. With these transitions metals in the lamellar structure this systems might be a good precursor in the formation of oxides of the metals that constitute the compound in order to be used in catalysis<br>Mestrado<br>Quimica Inorganica<br>Mestre em Química

Developing a catalyst that accepts a wide range of fuels for hydrogen production is an important design aspect for the successful multi-fuel reformer. This thesis aims to synthesize and evaluate Ni-Cu/Al\(_2\)O\(_3\) catalysts for methanol and methane steam reforming. Detailed characterizations of catalysts, as well as the role of the bimetallic nature of Ni-Cu metals on the catalytic reaction are presented and discussed. A series of Ni\(_x\)-Cu\(_y\)/Al\(_2\)O\(_3\) catalysts with various metals loadings (x= 10, 7, 5, 3 and 0% weight and y= 0, 3, 5, 7 and 10%, respectively) were prepared. The temperature programed reduction revealed that bimetallic catalysts displayed a new hydrogen uptake peak compared with monometallic metal catalyst and this was attributed to NiCuO reduction. The X-ray diffraction patterns indicated Ni\(_x\)Cu\(_1\)\(_-\)\(_x\)O phase formation. The methanol steam reforming was evaluated over the prepared catalysts over the range of temperatures 225-325°C in a fixed bed reactor. It was found that bimetallic Ni-Cu had a strong influence on the amount of CO\(_2\) and CO by controlling the water gas shift reaction and decomposition reaction. The highest amount of hydrogen produced among the other prepared catalysts was 2.2 mol/mol-CH3OH for 5%Cu-5%Ni at 325°C. Low temperature methane steam reforming at 500-700°C was investigated. The synergetic effect between Cu and Ni metals was also investigated, showing that Cu provides a stabilizing effect by forming Ni-Cu alloy and controlling the catalyst structure. The 7%Ni-3%Cu revealed the highest conversion of 71.1% methane and produced the maximum amount of hydrogen at 2.4 mol/mol-CH4 among the other prepared catalysts at 600°C and S/C of 3. The bimetallic reacted Ni-Cu catalysts revealed less carbon selectivity (0.9% for 5%Ni-5%Cu) compared to 10%Ni (4.6%) catalyst at 600°C.

Nous avons etudies diverses reactions de substitution d'halogenures aliphatiques, vinyliques et aromatiques par des composes organomanganeux et organozinciques, en presence de sels de cuivre, de fer ou de nickel. L'alkylation des composes organomanganeux est realisee a la temperature ambiante dans un melange thf/nmp en presence de 3% de sels de cuivre (cucl#4li#2). Il est possible d'obtenir d'excellents rendements en utilisant des bromures, des iodures et des sulfonates d'alkyles primaires. La reaction est tres chimioselective en presence de nombreux groupes fonctionnels (halogenures, esters, cetones). Nous avons aussi etudie la substitution d'halogenures aromatiques par des composes organomanganeux. Cette reaction est catalysee par des sels de nickel (ni(dppe)cl#2 ou ni(dppp)cl#2). Elle est effectuee dans le thf, a la temperature ambiante et permet d'obtenir de bons rendements. Nous avons egalement montre que l'alcenylation des derives organomanganeux est catalysee par des sels de fer. La reaction est conduite a la temperature ambiante en presence de 3% de fe(acac)#3 dans un melange thf/nmp. Dans de nombreux cas (iodures, bromures et meme chlorures vinyliques) la reaction donne de tres bons rendements et la stereoselectivite est excellente. Les organocuprozinciques mixtes substituent des iodures vinyliques avec de bons rendements lorsque la reaction est conduite dans le dmpu ou la nmp a 60c. Ce sont des composes tres chimioselectifs. Ils permettent ainsi d'acceder stereospecifiquement a des alcenes polyfonctionnalises tres varies

O hidrogênio é considerado uma fonte ideal de energia, pois sua combustão não gera contaminantes, apenas água. Dentre os processos disponíveis para produção de hidrogênio, destaca-se a decomposição catalítica do metano, pois, ao contrário do que ocorre na reforma a vapor e na oxidação parcial, nesta rota não há produção de CO. O objetivo deste trabalho é o estudo cinético e a determinação da taxa da reação de decomposição do metano sobre catalisador tipo óxido misto (Cu-Ni-Al) para obtenção de hidrogênio de alta pureza. O catalisador foi separado em quatro faixas de granulometria a fim de se determinar a influência da difusão interna à partícula na velocidade da reação, e o critério de Mears foi utilizado para avaliar o efeito da difusão externa. Os resultados obtidos mostram que, nas condições estudadas, os efeitos difusivos não influenciam significativamente a velocidade da reação. A seguir, a reação foi realizada sob diferentes temperaturas (500 a 600°C) e concentrações de metano (0,5 a 1,2 mol m-3), para determinação da equação da taxa. Observou-se que a reação é de primeira ordem, com uma energia de ativação de 50655 J mol-1. Além do hidrogênio, a reação forma carbono que se deposita na superfície do catalisador causando sua desativação. Os efeitos da regeneração do catalisador por oxidação deste carbono também foram investigados. Repetidos ciclos de reaçãoregeneração foram executados, sendo a regeneração realizada por oxidação do carbono com ar sintético ou por oxidação e redução. A oxidação foi conduzida a diferentes temperaturas (500 a 600°C) e intervalos de duração (20 a 75 min), com a reação ocorrendo em condições severas (600°C e 1,2 mol m-3 de metano). A melhor condição de regeneração, ou seja, aquela que permite um maior número de ciclos com baixa perda de atividade, foi determinada. Observou-se, também, que o carbono depositado apresenta a forma de nanotubos, os quais têm se tornado um dos campos mais ativos da nanociência e da nanotecnologia, devido a suas propriedades excepcionais. Os nanotubos de carbono formados durante a reação foram analisados, quanto a sua estrutura, por Microscopia Eletrônica de Varredura (MEV).<br>Hydrogen is considered the ideal source of energy, because its combustion doesn't generate pollutants, just water. The catalytic decomposition of methane stands out among the available processes for hydrogen production because, unlike steam reform and partial oxidation, in this route there is not production of CO. The objective of this work is the kinetic study and the reaction rate determination of methane catalytic decomposition over Cu-Ni-Al catalyst for pure hydrogen production. In order to determinate the limiting step, reaction was conducted using four catalyst particle size ranges and the Mears criterion was applied. The external diffusion effects and diffusion in porous catalysts step do not influence significantly the reaction rate in the studied conditions. The reaction was carried out in a thermobalance with different temperatures (500 to 600°C) and methane concentrations (0.5 to 1.2 mol m-3) to determining the reaction rate. It was observed that the reaction is of first order, with activation energy of 50655 J mol-1. The reaction also forms carbon, which is deposited on the catalyst surface causing deactivation. The carbon oxidation for catalyst regeneration was also investigated. Repeated reaction-regeneration cycles were carried out, being the regeneration composed by oxidation or by oxidation and reduction. The oxidation was carried out at different temperatures (500 to 600°C) and times (20 to 75min), with the reaction happening in severe conditions (600°C and methane concentration of 1.2 mol m-3). The best regeneration condition, that is, the condition that allows a larger number of cycles with low activity loss, it was determined. It was also observed that the deposited carbon is in the nanotubes form, which has exceptional properties. The structure of carbon nanotubes formed during the reaction was analyzed by Scanning Electron Microscopy (SEM).

L'application d'une procédure cyclique d'exposition au méthane puis d'hydrogénation du film hydrocarboné formé conduit, sur le Ni-Cu 50/50, à la désorption d'hydrocarbures saturés de C1 à C10 avec une forte sélectivité en faveur des dérivés du cyclohexane. L'analyse thermodynamique montre que la barrière thermodynamique de la transformation du méthane en hydrocarbures supérieurs est franchie grâce au retrait de l'hydrogène libéré à une faible pression partielle lors de l'étape d'exposition. L'augmentation des pressions de méthane et d'hydrogène est bénéfique dans la procédure cyclique utilisée. En effet, l'envoi de méthane à pression élevée (30 bars) permet de ramener à quelques secondes les durées d'exposition en accélérant la formation du film hydrocarboné. L'élévation de la pression d'hydrogène jusqu'à 30 bars fait croître les quantités de C2+ recueillies et la sélectivité en C5+. Il est ainsi possible, dans certaines conditions, d'atteindre des sélectivités de 90% en C5+. Cependant, le retour au méthane reste important puisque, typiquement, environ le quart du méthane adsorbé est converti.

Des dépôts minces de palladium (taux de couverture 0 = 0-8 monocouches) ont été vapodéposés sur la face (110) de monocristaux de nickel, cuivre et or, avec l'objectif de réaliser des couches sous différents états de contrainte (-9. 5%, -7% et +7% respectivement). L'activité catalytique de ces dépôts de palladium, mesurée pour la réaction test d'hydrogénation du butadiène est extrêmement variable, avec des rendements pouvant dépasser de plus d'un facteur dix le rendement de la surface de référence Pd(110). Les dépôts caractérisés par les techniques de microscopie à effet tunnel, de diffraction d'électrons de basse énergie et de spectroscopie d'électrons Auger, montrent des restructurations importantes. Ce travail constitue une tentative pour établir un lien entre état de contrainte, restructuration et réactivité, la finalité étant la réalisation de structures superficielles intéressantes pour les processus catalytiques. L'étude des dépôts de Pd sur Ni(110) montre une croissance bidimensionnelle du Pd pour laquelle la relaxation de la contrainte épitaxique génère deux types de surstructures. Avec les dépôts de 1 -1. 5 MC, la relaxation dans la direction [1-10] engendre une structure (N x 1); N=5-11. Puis pour 0 = 4 MC, la relaxation opère dans la direction perpendiculaire [001] et une structure (N x 2) apparaît avec N=9-11. A l'échelle atomique ces reconstructions de surface sont très différentes de la surface (110) de départ. La topographie des dépôts de Pd sur Cu(l10) est plus complexe que précédemment car elle est influencée par la formation d'un composé défini. Le premier stade (0 < 0 < 0. 75 MC) de la croissance est bidimensionnel avec la formation probable d'un composé de type PdCu3, puis à partir d'un taux de couverture de 1 MC, la croissance devient tridimensionnelle. Les îlots, allongés selon la direction [1-10], permettent une relaxation partielle de la contrainte par les bords de marches dans la direction [001]. La relaxation de la contrainte dans la direction [1-10] ne s'opère qu'à partir de 0 = 1. 5 MC avec l'apparition d'une surstructure (N x -) (N=20-30) qui paraît similaire à celle obtenue pour les dépôts de Pd surNi(11O). La croissance de Pd/Au(110) suit un mode couche par couche en site avec la formation d'un alliage de surface jusqu'à un taux de couverture de 4 MC, puis le film de surface devient tridimensionnel avec l'apparition d'îlots allongés selon la direction [1-10]. Il faut noter qu'aucune ondulation de surface n'a été détectée pour ces dépôts de Pd sur Au( 110). La comparaison entre les propriétés catalytiques et les topographies des surfaces des dépôts permet d'établir un lien entre la contrainte épitaxique, la structure et la réactivité. On observe que lorsque la reconstruction (N x -) est présente, i. E. Pour les dépôts de Pd sur Ni(110) et Cu(110), les surfaces sont beaucoup plus actives (x 15-35) que la surface de référence Pd(110), pour la réaction test d'hydrogénation du butadiène. Il semble donc que cette structuration (N x -), générée par la relaxation de la contrainte épitaxique, est directement reliée à l'augmentation d'activité. Une contrainte d'épitaxie est bien susceptible de modifier la réactivité, d'une surface, via la modification du paramètre de maille et de la densité d'états locale. Cependant nos résultats ne militent pas en faveur d'une telle relation directe entre contrainte et réactivité. La conclusion est plutôt que les processus de relaxation, engendrés par la contrainte, peuvent générer de nouvelles structures superficielles favorables à l'accroissement des réactivités catalytiques.

Ce travail de thèse a porté sur l'élaboration de nanoparticules et de couches minces d'oxydes spinelles mixtes de MxCo2-xMnO4 (M = Ni, Cu, Zn ; x = 0, 0,15, 0,30, 0,60) semi-conducteurs, absorbants de lumière avec d'intéressantes applications potentielles pour la photo-catalyse et le photovoltaïque. Le premier chapitre présente tout d'abord une vue globale du contexte énergétique à l'échelle mondiale et des ressources d'énergie renouvelables, alternatives aux énergies fossiles les plus répandues. Une revue détaillée est ensuite faite des différents matériaux et systèmes employés dans la fabrication de cellules solaires, en portant une attention plus particulière à un nouveau type de cellules photovoltaïques en couches minces, dites " Tout-oxyde ", basées notamment sur l'utilisation d'oxydes de type spinelle utilisés comme absorbeurs solaires. Le deuxième chapitre présente les techniques expérimentales de synthèse et de caractérisation utilisées lors de ce travail de thèse. Le procédé de polycondensation inorganique, optimisé au laboratoire, utilisé pour synthétiser les poudres d'oxydes à basse température (T &lt; 120 °C) sans agent organique complexe est décrit. Ensuite, les méthodes de préparation de dispersions colloïdales à l'ambiante dans l'éthanol et de films minces homogènes d'oxydes par trempage-retrait sont explicitées. Le troisième chapitre présente les résultats détaillés des structures atomiques et électroniques des matériaux de base à l'étude, issus de calculs par la méthode Density Functional Theory (DFT), réalisés en collaboration avec le laboratoire CEMES de Toulouse. Les résultats des calculs de densités électroniques et détermination de structures de bandes, réalisés pour la première fois à notre connaissance, sur l'ensemble de la solution solide MnxCo3-xO4 (0 = x = 3), sont comparés à nos données expérimentales, obtenues notamment sur les largeurs de bande interdite (gap) à partir de mesures optiques faites sur couches minces. Un gap de 0,8 eV est calculé, qui serait dû à des transitions inter-métalliques en sites B. Deux gaps à 1,5 et 2,2 eV, obtenus expérimentalement dans l'UV-VIS, qui augmentent avec la quantité de manganèse, correspondraient à des transitions respectives B-A et O-B, respectivement. Les propriétés magnétiques de ces matériaux sont également discutées. Le quatrième chapitre présente l'élaboration et la caractérisation (micro-)structurale des poudres et des couches minces d'oxydes de type spinelle. Toutes les compositions (Co2MnO4 dopé au Ni, Cu ou Zn) cristallisent dans une phase cubique. Les nanoparticules sont sphériques avec la taille variant entre 20 et 50 nm. Les couches minces homogènes ont été déposées sur quartz, alumine, nitrure de titane et platine afin de mesurer leurs propriétés électriques et optiques. Une température de frittage environ de 1000 °C sous air a été déterminée par dilatométrie et les couches sont stables jusqu'à 900 °C quel que soit le substrat. En revanche, seules les couches déposées sur platine permettent d'atteindre la température de frittage sous air (et d'accroitre la compacité donc la conductivité des couches) sans réaction avec le substrat. Le chapitre cinq présente les variations des propriétés optiques et électriques des couches minces avec le frittage. Les propriétés d'absorbance de lumière des couches minces ainsi préparées, mesurées sur une gamme de longueurs d'ondes du domaine spectral UV-visible, montrent deux bandes d'absorbance, correspondantes à deux valeurs de gap pour chaque composition. La propriété d'absorbance des couches minces augmente dans la gamme du visible après frittage et les gaps diminuent. Les couches minces sont plus compactées. La résistivité des couches minces diminue de 105 à 102 Omega.cm avec l'augmentation de la température de 20 à 300 ºC. Une étude parallèle, basée sur la préparation de films minces absorbants de lumière de Co2MnO4 et Cu2O par la technique de Pulsed Laser Deposition (PLD) est également présentée<br>The present thesis deals with the synthesis and structural characterization of transition metals doped cobalt and manganese based spinel oxides MxCo2-xMnO4 (with M = Ni, Cu, Zn and x = 0, 0.15, 0.30, 0.60), in relationships with their conduction and optical properties. These materials are good p-type semiconductors and light absorbers in the UV and visible regions, therefore interesting for photo-catalysis and photovoltaics. The first chapter is a brief overview of the energy context and nature of global warming, renewable energy resources and a literature review of materials used for solar cells including the newly studied system type based on all-oxide photovoltaics. Chapter two presents all the experimental methods and characterization techniques used for this research work. The inorganic polycondensation method optimized in our laboratory and used for synthesizing spinel oxide powders at low temperature (T &lt; 120 °C) without complex organic agents is described. Then, the preparation of colloidal dispersions stabilized at room temperature using an azeotrope solution based on absolute ethanol and water only is described, in order to obtain homogenous oxide thin films by the dip-coating technique. The third chapter presents detailed results on the atomic and electronic structures of the materials under study performed by using a full density functional theory investigation thanks to a collaboration with the CEMES. First principles electronic structure calculations were performed for the first time to our knowledge over the whole spinel oxide solid solution range MnxCo3-xO4 (0 = x = 3), and compared with our experimental data. A small band gap of ~ 0.8 eV is calculated, due to metal-metal transitions in B sites. The experimental band gaps observed at 1.5 and 2.2 eV, which increase with the amount of manganese, would correspond to B-A and O-B transitions, respectively. The magnetic properties of these materials are also discussed. Chapter four shows the experimental details of the preparation and characterization of the spinel oxide powders, colloidal dispersions and thin films. All samples (Ni, Cu or Zn-doped Co2MnO4) are well crystallized with a single cubic spinel oxide phase. Nanoparticles are spherical and their diameters vary from 20 to 50 nm, doping with Zn, Ni to Cu, mainly due to steric effects. Homogenous oxide thin films were deposited on quartz, alumina, titanium nitride and platinum in order to measure their optical and electrical properties, and to increase the film compactness (thus electrical conductivity and light absorbance) after thermal treatment. Thin films are well preserved up to 900 °C in air and can handle higher temperatures (up to 1000 ºC) on platinum without reaction with the substrate. Chapter five deals with the optical and electrical properties of thin films before and after sintering. The optical properties were measured over a wide range of wavelengths (UV-VIS). The optical properties of spinel oxide thin films show two strong absorption band gaps for each composition at the UV front and close to 700 nm in wavelength. These band gaps are direct and mostly lower than 2 eV for the first band. Both band gaps increase with further doping and decrease after annealing. Thin film resistivity is about 105 .cm at room temperature and decreases with increasing temperature (a few tens of 20cm at 300 ºC). In parallel to the soft chemistry method and dip-coating technique used to prepare our spinel oxide thin layers, Pulsed Laser Deposition technique was used to prepare pure Co2MnO4 and Cu2O dense thin films. Their structural and optical main features are discussed

En los últimos años los ligando hemilábiles P,X (X= S,O), han sido de gran interés en el ámbito de la catálisis homogénea debido a que posee diversos heteroátomos en su estructura, con distinta capacidad coordinante. El objetivo de la presente tesis doctoral ha sido en el estudio de la reactividad de una serie de ligandos hemilábiles mono y difosfina con diferentes metales de transición y la evaluación de los correspondientes complejos en diversos procesos catalíticos. Se han obtenido diversos ligandos hemilábiles, siguiendo los procedimientos de síntesis desarrollados en nuestro grupo de investigación con anterioridad. Los ligandos obtenidos han sido el ligando bis-(2-difelnilfosfino)feniltioéter (DPTphos) y sus derivados monosulfurado P=S (DPTS) y disulfurado P=S,P=S (DPTS2),el compuesto bis(2-((difenilfosfino)metil)feniltioeter (DPTm) y la (2-fenilfosfino)-difeniltioéter (MPT). En el caso del ligando DPTm se han hecho ciertas mejoras en la síntesis ya descrita, y para la MPT se ha encontrado una ruta sintética alternativa, lo cual ha mejorado considerablemente los rendimientos de dichas reacciones. Se ha estudiado la reactividad de los ligandos DPTphos, DPTS1, DPTS2, DPTm y MPT con Ni(II) y los ligandos DPTm y MPT con Cu(I), Ag (I), obteniéndose diversos compuestos de coordinación. Dichos compuestos de coordinación han podido ser aíslados y caracterizados por las técnicas habituales de espectroscopía IR, RMN de 1H, 13C{1H} y 31P {1H}, microanálisis elemental, espectrometría de masas de alta resolución, y en los casos en que ha podido obtener cristales de cálidad adecuada, se ha hecho la resolución de la estructura cristalina mediante difracción de rayos X. Los compuestos de Cu(I) y Ni(II) obtenidos se han evaluado como agentes catalíticos para la formación de diariltioéteres por medio de reacciones de condensación de Ullmann. En el estudio de los blancos correspondientes a los ensayos anteriores, se ha podido observar la elevada efectividad catalítica de los sistemas consistentes en sales de Ni(II) y en ausencia de ligando, en el medio NaOH-DMF. En este caso, es posible obtener rendimientos de más del 99% en media hora de reacción. Estos estudios se han extendido a sales de Cu(I) con muy resultados. Se ha desarrollado nuevos métodos de obtención de diariltioéteres a partir de los correspondientes ariltiolatos y yodoarilos, utilizando NiCl2 como catalizador. La principal ventaja de estos procesos, es la ausencia de ligandos añadidos en el sistema catalítico. También podemos destacar, la obtención de altos rendimientos en cortos tiempos de reacción, a temperaturas no muy elevadas y con proporciones de catalizador inferiores a muchos de los procesos descritos en la bibliografía.

Les Hydroxydes Doubles Lamellaires (HDL) présentent de nombreux domaines d'application en rapport avec leur structure lamellaire et la diversité de leur de composition. Ce travail souligne les potentialités des HDL lorsqu'ils sont utilisés comme précurseurs d'oxydes mixtes pouvant intervenir en catalyse hétérogène acido-basique ou d'oxydo-réduction.<br />La première partie du mémoire concerne l'étude d'une série d'oxydes à base de nickel, cuivre, magnésium et aluminium, obtenus par calcination des HDL précurseurs à 450°C. La caractérisation structurale et l'étude de l'acido-basicité des oxydes mixtes en fonction de leur composition ont été réalisées. Elles s'appuient sur l'utilisation complémentaire de différentes méthodes analytiques physico-chimiques donnant accès à des informations concernant à la fois la structure, la composition et la morphologie des cristaux obtenus(DRX, ATG, analyse chimique, SPX...), ou permettant la caractérisation de leurs propriétés acido-basiques (adsorption de molécules sondes suivie par microcalorimétrie et SPX).<br />La seconde partie du travail est consacrée à l'utilisation des oxydes mixtes obtenus après calcination à 800°C pour la synthèse de nanofilaments de carbone à partir de la décomposition catalytique du méthane. Après une étude détaillée des oxydes mixtes, les nanofilaments produits ont été caractérisés à l'aide de différentes techniques, notamment la microscopie électronique à transmission. Les données physico-chimiques obtenues ont mis en évidence les relations entre les caractéristiques du catalyseur (composition, mode de synthèse, propriétés...) et le type des nanofilaments (tubes, fibres) obtenus.

碩士<br>國立臺北科技大學<br>化學工程研究所<br>102<br>In this study, methane steam reforming reaction over Ni-SSZ and Cu/Ni-SSZ catalysts was investigated. The activity of Cu/Ni-SSZ prepared at reduced atmosphere under various temperatures shows the higher H2 production rate than that of the Ni-SSZ catalyst. The addition of Cu not only reduces the production and selectivity of CO, but also affects methane decomposition rate. The morphology of the catalysts after the reaction was analyzed by SEM. Results show that filamentous carbon was deposited on the surface. The XRD results show that the addition of Cu atoms can prevent the Ni from sintering during the reduction pretreatments and the reforming reaction. The amount of carbon deposition on the catalyst measured by TGA indicates that the addition of Cu can minimize the carbon formation during the reaction. Furthermore, Raman analysis showed that the high intensity of G bond was noticed in Ni-SSZ catalyst and D-bond in Cu/Ni-SSZ catalyst. The addition of Cu would also affect the catalytic properties. For the Cu/Ni-SSZ catalyst thermally treated at 300℃ for two hours under reduction atmosphere shows the best catalytic performance.

碩士<br>大同大學<br>材料工程研究所<br>93<br>We synthesized carbon nanofibers(CNFs) by catalytic chemical vapor deposition(CVD) using an Al-Ni-Cu composite catalyst. Two different mixture gases (CH4/H2 and CH4/N2) were introduced as the reactants. The deposition processes were carried out at temperatures in the range of 650℃-750℃ with a 50℃ interval. We found that 700℃ is the most suitable synthetic temperature to produce high yield and thinner CNFs with Al-Ni-Cu catalysts. HRTEM showed that the as-grown CNFs have a bamboo-like structure. A 3M HCl acid solution was used to remove the catalysts from the as-grown CNFs. TGA results showed that this process could remove 30wt% catalysts from 0.5g CNFs(700℃, CH4/H2). SEM images showed CNFs lost the catalysts from the tips and leave cavity at the tip position. Heat treatments were also performed on CNFs which were produced using both CH4/H2 and CH4/N2 atmospheres at 700℃. At the annealing temperature of 2400℃, the loop structure was observed in HRTEM for CNFs produced by a CH4/H2 mixture gas. With the heat treatments, the Raman spectrums of CNFs showed clearly 2D band that have a stronger intensity in comparison with the G band. No obvious loop structure has been seen on the surface of CNFs which were produced by a CH4/N2 atmosphere and were heat-treated at 2400℃. And the intensity of 2D band is also weaker than that of G band. Metal particles were evaporated after a 2400℃ heat treatment. XRD data showed that the composite catalyst transformed into AlNi3 and AlNi phases during 1600℃-2000℃.

碩士<br>長庚大學<br>化工與材料工程研究所<br>94<br>The goal of this thesis is anticipated to develop some high performance catalysts for recycle of carbon dioxide and chemical conversion of CO2 to CO by means of catalytic reaction. This study contains: (1) the reverse water gas shift (RWGS) reaction on Ni/Al2O3 with and without；(2) the new Cu catalysts prepared by atomic layer epitaxy (ALE) technique applied in CO2 conversion to CO. One can see that CO and CH4 are the major products during RWGS reaction on Ni/Al2O3 and K-Ni/Al2O3 catalysts. The catalystic activity of Ni catalysts will slightly decrease with increasing amount of K additives, but the K promoter can effectively boost the reaction selectivity of CO. The CO2-TPD method is used to realize the adsorption sites of CO2 on Ni surface. It is found that K can promote to generate new adsorption sites on Ni, leading to increase activity if Ni catalysts. Interstingly, large amount of carbon deposition are found on Ni/Al2O3 contating K catalysts during reaction. The material of carbon deposition is analyzed by SEM, TEM and Raman spectrometer to find that there are some carbon fiber and disorder carbon structure formed on K-Ni catalysts surface. The formation carbon deposition is associated with K adding, tempersture (only for 500℃) and H2/CO2 ratio (H2 rich). The ALE Cu catalysts including: Cu/SiO2 and Cu/TiO2 are also applied to the RWGS reaction. Comparing to the typical impregnating Cu catalysts, these ALE Cu materials with low metal content and high dispersion can provide surprisightly highly catalytic activity.

碩士<br>國立臺灣科技大學<br>化學工程系<br>94<br>Abstract The major purpose of this study is to investigate the effect of Co, Ni, Sn addition on CuO-CeO2 catalysts for CO oxidation under rich hydrogen. The catalysts were prepared by sol-gel method and citric acid was used as chelating agent. The calcination temperature varied from 500℃ to 700℃. All the catalysts were characterized by BET, TPR and XRD. BET analyses showed that small amount addition of promoter can increase the BET surface area of CuO-CeO2 catalysts. The BET surface area decreased with increasing calcination temperature for all the catalysts. The XRD patterns showed that only CeO2 peaks were found for all the catalysts when calcined at 500℃. However, when the calcined temperature rose to 600℃, a small Cu peak was detected. The TPR profiles showed adding less promoter into CuO-CeO2 catalysts could cause the reduction peak shift toward lower temperature. With higher calcination temperature, the β peak would shift toward higher temperature. For CO oxidation under rich hydrogen, the addition of Ni、Sn would increase the Cu/Ce catalyst activity but Co decreases the catalyst activity. The experimental data showed that the optimal calcination temperature for the catalyst activity depends on the promoter added. For Sn addition, the optimal calcination temperature is 600℃, while for the other promoters, the optimal calcination temperature is 500℃. Expermental also found that all the catalysts would be deactivated by water vapor.

博士<br>元智大學<br>化學工程與材料科學學系<br>106<br>In this study, catalytic nickel-gallium (Ni5Ga3) and Cu-based catalysts (CuO-ZnO-Al2O3, CZA) have been prepared with co-precipitation methods. Supported nickel-gallium and Cu-based catalysts have also been obtained by ultrasonic-stirring with supports including silica gel (SiO2), protonated Y-type zeolite (HYZ) and protonated Beta-type zeolite (HBZ) in a slurry form. Crystal structures and morphologies of catalysts have been investigated and observed by X-ray diffraction (XRD) and field-emission scanning electronic microscopy (FE-SEM), confirming that nickel-gallium and Cu-based catalysts were Ni5Ga3 and CuO-ZnO-Al2O3 structure. FE-SEM microphotos have shown that supports could maintain the particle size being uniform in the durations of MeOH and DME formations. X-ray photon spectroscopy (XPS) spectra indicated that the effective component in Ni-Ga and Cu-based catalysts were respectively gallium and copper species. Oxidation state and bond distances of metal and its neighbour atoms were analyzed by X-ray absorption near-edge structure (XANES)/Extended X-ray absorption fine structure (EXAFS). It displayed that the oxidation states of gallium were Ga(0) and Ga(III) before and after MeOH formation, but nickel remained Ni(0). For Cu-based catalyst, the oxidation states of copper and zinc were Cu(II) and Zn(II), respectively. The inverse relationship of bond distances of metal (Ni5Ga3: Ni and Ga; CZA: Cu and Zn) and its neighbour atoms during the reaction were exhibited in EXAFS excluding Ni5Ga3/SiO2, CZA/HYZ, and CZA/HBZ. It demonstrated that structure, morphology, chemical composition, and fine structure of catalyst could be remained during MeOH/DME formation by dispersing nickel-gallium and Cu-based catalysts onto supports. In addition, the produced species sorts and their concentrations have been respectively analyzed using a dual fixed-bed catalyst-filled column reactor with an online FTIR (Fourier transformed infrared spectrum) and GC (gas chromatograph) spectra at the terminal to obtain the conversion of feedstock and the selectivity/yield of products. Online FTIR and GC spectra show that catalytic performances of catalysts at a constant pressure and variable temperatures (P=50 bar, T=150, 250, and 350 oC) of Ni-Ga and Cu-based catalysts have been enhanced after nickel-gallium and Cu-based catalyst dispersed onto supports. The highest MeOH yield could reach to 62.1 (150 oC), 84.7 (250 oC), and 82.5% (350 oC) by using Ni5Ga3/SiO2. The highest DME yield of CZA was 60.2%; it could be raised to 71.5% (CZA/HYZ) by loading onto HYZ, but lowered to 31.8% by supporting onto HBZ (CZA/HBZ). Rate equilibrium constants of MeOH formation were 0.150 (150oC), 0.473 (250 oC), and 0.477 h-1 (350 oC) that were much higher than theoretical values of 4.67×10-4 (150 oC), 2.22×10-5 (250 oC), and 2.47×10-6 (350 oC) h-1 by using Ni5Ga3 catalyst. Activation energies of MeOH formation using Ni5Ga3 and Ni5Ga3/SiO2 were 3.21 and 2.72 kJ/mol, respectively. In terms of DME formation, the highest rate equilibrium constant using CZA was 1.65×103 L/mol-h. It could be raised to 2.26×103 L/mol-h L/mol-h after supporting onto HYZ (CZA/HYZ), but lowered to 0.70×103 L/mol-h using CZA/HBZ. Activation energies of DME formation using CZA, CZA/HBZ, and CZA/HYZ were respectively 2.04, 2.26, and 1.16 kJ/mol. In addition, Gibbs energies of MeOH formation were 6.67 (150 oC), 3.26 (250 oC), and 3.83 (350 oC) kJ/mol that were much lower than theoretical values including 26.97 (150 oC), 46.59 (250 oC), and 66.87 (350oC) kJ/mol. The Gibbs energies of DME formation by using CZA, CZA/HBZ, and CZA/HYZ were respectively -40.07, -40.00, and -40.67 kJ/mol that were much lower than theoretical values of -12.64, -9.96, and -7.28 kJ/mol. Eventually, the cost assessment for a 10-TPD (ton per day) off-gas utility process of a petrochemical refinery plant showed that the daily income was USD$ 5,002,359/d with 3.49 years of payback.

碩士<br>國立臺灣科技大學<br>化學工程系<br>102<br>Methane utilization and hydrogen as a new energy carrier are among the more pursued energy research subjects, wherein methane reforming (SRM) is an important reaction. Industrial SRM operates at high temperature, e.g., 700oC and above. However, mid-temperature (300-500oC) SRM can have an advantage in reducing the energy consumption. This study develops highly efficient Cu-Ni catalysts for mid-temperature SRM based on our previous experience in ethanol steam reforming. NiO is used as an active support to provide active oxygen species that can significantly reduce the selectivity of methane in SRE, and therefore, it may activate methane for SRM. However, the Cu-Ni catalyst deactivated when tested for SRM up to 500 oC when NiO became completely reduced. Therefore, we modified Cu-Ni catalyst by doping with La, Li, or Gd. Experimental results show that Gd doping in Cu-Ni catalyst can effectively catalyze SRM with high CH4 conversion, and increase H2 yield in the temperature range of 375-500oC. Gd doping also decreased the degree of deactivation of the catalyst. From the characterization, Cu-Ni catalyst with Gd doping had higher metal dispersion and higher TOF (turnover frequency) than the undoped catalyst.

Title: Electronics and adsorption properties of model catalytic systems contains cerium Author: Miloš Cabala Department: Department of Surface and Plasma Science, Supervisor: RNDr. Kateřina Veltruská, Department of Surface and Plasma Science, Abstract: The doctoral thesis contains the study of model catalyst systems based on cerium and ceria. The thesis deals with model systems of CeAg, CeO2/Cu(111), Ni- CeO2/Cu(111) a Ni-Sn-CeO2/Cu(111). We have studied these systems using photoelectron spectroscopy, ion scattering spectroscopy and low energy electron diffraction. Model systems were prepared under strictly defined conditions. The strong bimetallic interaction was observed on the CeAg layers. Molecular adsorption of carbon monoxide on CeAg was demonstrated. We also observed intensive reaction of these layers with oxygen. By measurements in different directions of surface Brillouin zone, we managed to reconstruct the band structure of the prepared CeO2/Cu(111) layer. We have shown that the Cu substrate interacts weakly with deposited CeO2 layer. This interaction results in a charge transfer from Cu into CeO2. Overall, in the valence spectrum we have identified three main electron bands corresponding to O 2p state bound in CeO2. It has been proven that the deposition of Ni on CeO2 layers leads to partial...

碩士<br>中原大學<br>化學研究所<br>102<br>Several novel metal complexes incorporated by salen type which bearing BTP ligands (BTP = N,O-bidentate benzotriazole phenoxide), [(C83CBiIBTP)Cu] (1) , [(C83CBiIBTP)Pd] (2) , [(C83CBiIBTP)Zn2(OAc)2] (3) , [(C83CBiIBTP)Ni2(OAc)2] (4) , [(C83CBiIBTP)Co2(OAc)2] (5) were synthesized and structurally characterized. Their catalytic activities of carbon dioxide/cyclohexene oxide copolymerization were systematic studied. [(C83CBiIBTP)Ni2(OAc)2] (4) was active for the copolymerization of carbon dioxide/cyclohexene oxide in controlled manner, yielding poly(cyclohexene carbonate) with the highly molecular weights and narrow PDIs (Mn: 62300/28900 , PDI:1.06/1.05). Additionally, There were no evidence of cyclic carbonate being formed only when complex (4) as catalyst, and it showed good productivity (TON:2784) and activity (TOF:80). Although complex (5) and (3) were also a active catalyst for the copolymerization of carbon dioxide/cyclohexene oxide, its can not compared with the well defined (4). Therefore, the copolymerization activity is (4) > (5) > (3).