This work focuses on methane and ethanol conversion to hydrogen in the presence of a catalyst in order to increase the selectivity of the desired product (H₂) and reduce carbon monoxide emission and coke formation. Two kinds of active phase were used (copper and ruthenium) and impregnated on calcined hydrotalcites CoₓMg₆₋ₓAl₂ in order to be evaluated in the methane and ethanol steam reforming reactions. For both reactions, the influence of several factors was evaluated in order to adjust the reaction parameters. It has been shown that catalysts performances for the reforming reactions depend on the content of cobalt and magnesium. High cobalt content enhanced the catalytic activity. 1Ru/Co₆Al₂ catalyst presented the highest activity and stability in the methane steam reforming reaction among the other industrial and prepared catalysts even under a low GHSV and with no hydrogen pretreatment. Reduced ruthenium and cobalt were detected after the reaction by XRD. EPR technique was able to detect negligible amount of two kinds of carbonaceous species formed during the reaction : coke and carbon. On the other hand, 5Cu/Co₆Al₂ catalyst revealed the highest hydrogen productivity in the ethanol steam reforming reaction. However, it suffers from coke formation that deactivated the catalysts after few hours. 5Cu/Co₂Mg₄Al₂ catalyst showed a much lower quantity of carbonaceous species with no deactivating during 50 hours due to the basic character of the magnesium oxide phase present in the support.

Ce travail étudie la récupération de la fraction fermentescible des déchets. En effet, la matière organique se décompose en absence d'oxygène et produit simultanément du biogaz. L'une des technologies émergentes consiste à utiliser le CH₄ et le CO₂, les deux principaux composants du biogaz. C'est la réactionde reformage à sec du méthane (CH₄ + CO₂ → 2 CO + 2 H₂), particulièrement intéressante, car elle se permet de produire un gaz de synthèse avec un rapport H₂/CO proche de 1, avantageux pour plusieurs applications industrielles, et de se débarrasser de deux gaz à effet de serre. Cependant, vu son caractère endothermique, le reformage à sec du méthane nécessite l'utilisation d'un catalyseur, pour éviter d'avoir à opérer à des températures très élevées pour obtenir des conversions suffisantes. De plus, le reformage à sec du méthane s'accompagne de réactions secondaires, dont certaines conduisent à la formation de carbone. Dans ce contexte, les efforts sont orientés vers le développement de systèmes catalytiques ayant une bonne activité et une bonne résistance aux dépôts de carbone. Dans ce travail, des échantillons réels de biogaz sont analysés dans deux centres de biométhanisation, l'un en France et l'autre au Liban. Nos résultats montrent que le vrai biogaz est composé, outre des composants majeurs CH₄ et CO₂, de NH₃, H₂S, de quelques terpènes et de certains COV. Ensuite, des oxydes mixtes de Co, Ni, Mg et Al sont préparés en utilisant la voie hydrotalcite, afin d'obtenir des propriétés catalytiques intéressantes dans le reformage à sec du méthane. L'évaluation des performances catalytiques en présence de certaines impuretés présentes dans le biogaz telles que les composés organiques volatils (toluène) fait également partie de ce travail. Enfin, la toxicité du biogaz issu des centres de biométhanisation est évaluée. Des cultures de cellules pulmonaires humaines (BEAS-2B) sont ainsi exposées à l'interface air/liquide en utilisant le système Vitrocell®. Après exposition des cellules, un ensemble de marqueurs de toxicité est déterminé. Par cette étude, l'impact du biogaz sur la santé humaine sera évalué. / This work studies the energy recovery of the fermentable fraction of waste. Indeed, organic matter decomposes in the absence of oxygen and simultaneously produces biogas. One of the emerging technologies is to upgrade CH₄ and CO₂, the two major components of biogas. This is the dry reforming of methane (CH₄ + CO₂ → 2 CO + 2 H₂) (DRM), which is particularly interesting, since it makes possible to produce a synthesis gas with a H₂/CO ratio close to 1, advantageous for several industrial applications, and to get rid of two greenhouse gases. However, due to its endothermic nature, the dry reforming of methane requires the use of a catalyst, to avoid operating at very high temperatures in order to obtain sufficient conversions. Moreover, the dry reforming of methane is accompanied by secondary reactions, some of which lead to the formation of carbon. In this context, efforts have been focused on the development of catalytic systems with good activity and good resistance against carbon deposition. In this work, real biogas samples were analyzed at two biomethanation centers, one in France and the other in Lebanon. Thus, knowing the identity and the quantity of the various compounds, a study of their effect on the efficiency of the catalyst is done. Our results show that the real biogas is composed, besides the major components, CH₄ and CO₂, of NH₃, H₂S, some terpenes ans some VOCs. In addition, mixed oxides of Co, Ni, Mg and Al were prepared using the hydrotalcite route, in order to obtain interesting catalytic properties. The prepared systems were characterized by different physicochemical techniques and tested in the dry reforming of methane. The Co-Ni based system seems to be the best system joining the high activity of nickel with the high resistance of cobalt towards carbon deposition. The evaluation of the catalytic performances in the presence of some impurities that exist in biogas quch as volatile organic compounds (toluene) is also a part of this work. Finally, the toxicity of biogas collected from biomethanation centers was evaluated. Human lung cell cultures (BEAS-2B) were thus exposed at the air / liquid interface using the Vitrocell® system. After exposure of the cells, a set of toxicity markers is determined. In this study, the impact of biogas on human health will be evaluated.

Devido a crescente preocupação com relação ao efeito estufa e com o objetivo de obter produtos de maior valor agregado a partir dos gases CH4 e CO2, este trabalho estudou catalisadores de níquel suportados em diferentes óxidos (Al2O3, CeO2, MgO e ZrO2) promovidos com ZnO aplicados na reação de reforma seca de metano para obter gás de síntese (H2 + CO). Primeiramente foram estudados catalisadores de níquel suportados em ZrO2 dopados com diferentes teores de zinco: 0%, 5%, 12,5% e 25% a fim de selecionar o catalisador mais promissor para estudos posteriores. Também foram utilizados dois métodos de preparo: impregnação e co-precipitação. Os resultados de DRX mostraram que a adição de zinco estabilizou a fase tetragonal da zircônia em todos os teores de zinco e em ambos os métodos de preparo. As análises de RTP mostraram que os catalisadores impregnados sofreram maior redução do que os co-precipitados e para maiores teores de zinco foram necessárias maiores temperaturas de redução. Os testes catalíticos mostraram que o aditivo zinco não exerceu efeito sobre os catalisadores impregnados, porém para as amostras co-precipitadas notou-se um teor ótimo com relação à conversão de reagentes na reação e o catalisador 5Ni12ZZc apresentou os melhores resultados. A deposição de carbono também foi menor nos catalisadores co-precipitados. No estudo dos diferentes suportes, as análises de DRX sugerem a dopagem de todos os óxidos com zinco, pois houve mudanças no parâmetro de rede em todas as amostras. As análises de RTP mostraram que a adição de zinco diminui a temperatura de redução do catalisador suportado em alumina e, no suporte CeO2 o efeito é o contrário. Nos testes catalíticos observaram-se efeitos distintos: nos catalisadores Ni-ZnO-CeO2 e Ni-ZnO-MgO o efeito da adição de zinco causou diminuição na conversão dos reagentes, por outro lado, causou diminuição na deposição de carbono e inibição da formação do carbono grafite; nos catalisadores Ni-ZnO-Al2O3 a conversão de reagentes não se alterou com a adição de zinco porém houve uma diminuição na deposição de carbono. Os melhores resultados, portanto, foram apresentados pelo catalisador 5NiZnAl que converteu acima de 80% dos reagentes e não sofreu desativação pela deposição de carbono. / Due to the increasing concern related to the greenhouse effect and aiming to obtain products with higher added-value from CH4 and CO2 gases, nickel catalysts supported on different oxides (Al2O3, CeO2, MgO and ZrO2) promoted with ZnO were studied and applied to the dry reforming of methane reaction to obtain syngas (H2+CO). Firstly, ZrO2 supported Nickel catalysts doped with different zinc content: 0, 5, 12,5 and 25% molar ratio were used to identify and select the best amount of zinc to further studies. Two preparation methods were investigated: impregnation and co-precipitation. The XRD results showed that the zinc addition stabilized the zircon tetrahedral phase of all catalysts from both preparation methods. The TPR analyses showed that the impregnated catalysts reduced more than the co-precipitated ones and higher reduction temperature was needed for the catalysts with higher zinc content. The catalytic tests indicated that the zinc content did not have any effect over the impregnated catalysts, whilst for the co-precipitated samples, a great content was noted and the 5Ni12ZZc catalyst showed the best results. The co-precipitated catalysts also had lower carbon deposition. In the study of different supports, the XRD analyses showed that the zinc interacts with all the used oxides, because there were changes of the cell parameter of all samples. The TPR analyses indicated that the zinc addition lowers the reduction temperature of the alumina supported catalyst and the effect is opposite for the CeO2 support. Different effects were observed during the catalytic tests: for the CeO2 and MgO supported catalysts the effect of zinc addition caused a decrease in the conversion of reactants, but it lowered the deposition of carbon and inhibited the formation of graffiti carbon; for the Al2O3 supported catalysts, the reactant conversion was the same with the addition of zinc, however there was a reduction on the carbon deposition. Therefore, the best results were obtained for the 5NiZnAl catalyst, which converted over 80% of the reactants and wasn\'t deactivated by carbon deposition.

Made available in DSpace on 2016-06-02T19:56:37Z (GMT). No. of bitstreams: 1 2931.pdf: 6814472 bytes, checksum: 46c69cfcaa07e8f2ab4e1d803b03916a (MD5) Previous issue date: 2010-03-05 / Universidade Federal de Minas Gerais / Colloidal Nanoparticles of Platinum (Pt-NPs) were obtained by reducing hexacloroplatinic acid with ethylene glycol in the presence of polyvinylpyrrolidone (PVP) as protective agent of the particles. Two methods of synthesis were performed which differed by the ratio PVP / Pt used. The synthesis of nanoparticles was accompanied by measures in the UV-visible from of which it was possible to determine the end of the reaction. The Pt-NPs were characterized by Transmission Electron Microscopy (TEM) that determined the average diameter of particles (~ 2.0 nm). After the synthesis, the Pt-NPs were incorporated into the supports of alumina and alumina promoted with cerium and cerium-zirconium which were prepared by sol-gel method. Supporters with nanoparticles incorporated were then subjected to heat treatment have sought the formation of stable catalysts and without the presence of protective polymer, as this could affect the activity of the catalyst by covering the active sites. Through X-ray diffraction and TEM images it was possible to monitor the stability of samples after heat treatment and the samples that were synthesized with higher PVP were more stable. Measures of X-ray absorption fine structure (XAFS) spectroscopy in situ allowed the characterization of the samples in the reaction atmosphere. Through the analysis of extended X-ray absorption fine structure (EXAFS) was observed morphological changes in the particles caused by the increase in temperature showing that there is an increase in the number of atoms of low coordination when samples are heated which favors the reaction of steam reforming of methane. Through studies of X-ray absorption near edge structure (XANES) in the edges L2 and L3 of Pt was possible to monitor how the electron density of the catalysts varies in reaction conditions. Moreover, the catalysts were also tested catalysts. Measures of dispersion were obtained by the reaction of dehydrogenation of cyclohexane and catalysts made of alumina promoted with cerium and cerium-zirconium displayed less dispersion due to the coating caused by the support. The catalysts in which the particles were synthesized with a higher amount of PVP, because of its stability, were subjected to the reaction of steam reforming of methane and proved active. This reaction was used to calculate the value of the apparent activation energy. The catalysts containing promoters were more active than the catalyst only alumina thus showing the role of support in this reaction. Therefore, this system has proved very interesting to study the catalytic properties in reactions sensitive to the structure since the nanoparticles present are monodispersed and the catalyst is stable under reaction conditions allowing the study of structural and electronic properties. / Nanopartículas coloidais de platina (NPs-Pt) foram obtidas por meio da redução do ácido hexacloroplatínico por etilenoglicol na presença de polivinilpirrolidona (PVP) como agente protetor das partículas. Dois métodos de síntese foram realizados os quais se diferiram pela razão PVP/Pt empregada. As sínteses das NPs-Pt foram acompanhadas por medidas no UVvisível através das quais foi possível determinar o fim da reação. As NPs-Pt foram caracterizadas por microscopia eletrônica de transmissão (TEM) que determinou o diâmetro médio das partículas (~2,0 nm). Após a síntese as NPs-Pt foram incorporadas à suportes de alumina e alumina promovida com cério e cério-zircônio os quais foram preparados pelo método sol-gel. Os suportes com as nanopartículas incorporadas foram então submetidos a tratamentos térmicos com o objetivo de levar à formação de catalisadores estáveis e sem a presença do polímero protetor. Através de difração de raios X e imagens de TEM foi possível acompanhar a estabilidade das amostras após o tratamento térmico tendo sido as amostras sintetizadas com maior quantidade de PVP mais estáveis. Medidas de espectroscopia de estrutura fina de absorção de raios X (XAFS) in situ permitiram a caracterização da amostra em atmosfera de reação. Através da análise da região estendida após a borda, EXAFS, foi possível observar mudanças morfológicas nas partículas ocasionadas pelo aumento da temperatura mostrando que há um aumento no número de átomos de baixa coordenação quando as amostras são aquecidas o que favorece a reação de reforma a vapor do metano. Através de estudos da região próxima às bordas L2 e L3 da Pt (XANES) foi possível acompanhar como a densidade eletrônica dos catalisadores variou em condições de reação. Por fim, os catalisadores foram submetidos a ensaios catalíticos. Medidas de dispersão foram obtidas através da reação de desidrogenação do ciclohexano tendo os catalisadores preparados com alumina promovida com Ce e Ce-Zr apresentado uma menor dispersão devido ao recobrimento ocasionado pelo suporte. Devido à sua estabilidade, os catalisadores obtidos a partir das nanopartículas sintetizadas com maior razão PVP/Pt, foram submetidos à reação de reforma a vapor do metano e se mostraram ativos. Essa reação foi utilizada para calcular o valor da energia de ativação aparente. Os catalisadores contendo promotores foram mais ativos, mostrando assim o papel do suporte nessa reação. Portanto, essa abordagem se mostrou bastante interessante para o estudo das propriedades catalíticas em reações sensíveis à estrutura devido à estreita distribuição de tamanhos das nanopartículas e sua estabilidade em condições de reação permitindo o estudo detalhado de suas propriedades estruturais e eletrônicas

Catalisadores ativos e estáveis, preparados a partir dos hidróxidos duplos lamelares (HDLs) contendo os cátions Ni2+, Zn2+, Al3+ e Zr4+(NiZn-Al, NiZn-AlZr e NiZn-Zr), foram avaliados na reação de reforma seca do metano. Os precursores foram caracterizados por difração de raios X, confirmando a formação das fases para as amostras de NiZn-Al e NiZn-AlZr. As espectroscopias no infravermelho/Raman elucidaram a ocorrência dos ânions (CO32-) e das moléculas de água na intercamada. A Fisissorção de nitrogênio ( método de BET) determinou a presença de poros e a área superficial específica. As formas das isotermas foram do tipo IV, de acordo com a IUPAC, e representa uma estrutura mesoporosa. A análise termogravimétrica foi utilizada para determinar a temperatura de calcinação dos precursores para obtenção dos catalisadores e as temperaturas utilizadas foram 550 °C, 650 °C e 750 °C. Os resultados de difração de raios X dos catalisadores apresentaram uma mistura de óxidos binários (NiO, ZnO, ZrO2 e Al2O3) e óxidos ternários (NiAl2O4 e ZnAl2O4). As fases de espinélios foram observadas nos catalisadores obtidos a 650°C (Ni/ZnAl-6 e Ni/ZnAlZr-6) e 750°C (Ni/ZnAl-7 e Ni/ZnAlZr-7). A redução a temperatura programada de hidrogênio (TPR-H2) forneceu informações sobre a redução do catalisador. Os resultados exibiram interações entre a fase ativa com as outras fases presentes no intervalo entre 350 - 800 °C, enquanto que a dessorção àtemperatura programada de CO2 (DTP-CO2) mostrou que os catalisadores possuem sítios básicos fracos. Ademais, os catalisadores foram caracterizados por fisissorção de nitrogênio, microscopia eletrônica de varredura (MEV), espectroscopia Raman e basicidade usando um indicador de Hammett. O desempenho dos catalisadores foi avaliado na reação de reforma seca do metano utilizando uma razão molar de alimentação de CH4: CO2 = 1,5:1,0; a fim de simular a composição do biogás. Os resultados mostraram uma maior conversão para o CO2 em todos os catalisadores investigados, o que pode ser atribuído ao maior teor de CH4 alimentado. Além disso, é importante ressaltar a contribuição dos sítios básicos presentes nas amostras, o que pode também contribuir para a conversão do CO2. A maior conversão de CH4 foi observada para os catalisadores tratados a 750 °C. Após as reações, foi observada a formação de carbono grafite sobre todos os catalisadores, com menor percentual para a amostra Ni/ZnAl, calcinadas a 550 °C e 650 °C, e Ni/ZnZr-7, calcinada a 750 °C. Finalmente, os catalisadores calcinados a 650 °C e 750 °C também foram ativados na temperatura de 750°C e os resultados reacionais mostraram que essa temperatura favoreceu o processo de aglomeração e, portanto, promoveu baixas conversões para o CH4 e CO2. / Active and stable catalysts, prepared from the lamellar double hydroxides (HDLs) containing the cations Ni2 +, Zn2 +, Al3 + and Zr4 + (NiZn-Al, NiZn-AlZr and NiZn-Zr) were evaluated in the dry reforming reaction of methane. The precursors were characterized by X-ray diffraction method, confirming the formation of phases for NiZn-Al and NiZn-AlZr samples. Infrared / Raman spectroscopies elucidated the occurrence of anions (CO32-) and water molecules in the interlayer. Nitrogen physisorption (BET method) determined the presence of pores and the specific surface area. The shape of the isotherms were type IV, according to the IUPAC, representing a mesoporous structure. The thermogravimetric analysis was used to determine the calcination temperature of the precursors to obtain the catalysts and the temperatures used were 550 ° C, 650 ° C and 750 ° C. The X-ray diffraction results of the catalysts showed a mixture of binary oxides (NiO, ZnO, ZrO2 and Al2O3) and ternary oxides (NiAl2O4 and ZnAl2O4). The spinel phases were observed in the catalysts obtained at 650 °C (Ni/ZnAl-6 and Ni/ZnAlZr-6) and 750°C (Ni/ZnAl-7 and Ni/ZnAlZr-7) Temperature- programmed reduction with hydrogen (H2-TPR) provided information on catalyst reduction. The results showed interactions between the active phase and the other phases present in the range of 350 - 800 ° C, while temperature- programmed desorption of CO2 (CO2-TPD) showed that the catalysts have weak basic sites. In addition, the catalysts were characterized by Nitrogen physisorption, scanning electron microscopy (SEM), Raman spectroscopy and basicity using a Hammett indicator. The performance of the catalysts was evaluated in the dry reforming reaction of the methane using a CH4: CO2 molar feed ratio = 1.5: 1.0; In order to simulate the biogas composition. The results showed a higher conversion to CO2 in all the catalysts investigated, which can be attributed to the higher content of CH4 fed. In addition, it is important to restate the contribution of the basic sites present in the samples, which may also contribute to the conversion of CO2.The higher conversion of CH4 was observed for the catalysts treated at 750 ° C. After the reactions, the formation of graphite carbon was observed on all the catalysts, with a lower percentage for Ni / ZnAl samples, calcined at 550 ° C and 650 ° C, and Ni / ZnZr-7, calcined at 750 ° C. Finally, the catalysts calcined at 650 ° C and 750 ° C were also activated at the temperature of 750 ° C. and the reaction results showed that this temperature favored the agglomeration process and, therefore, promoted low conversions for CH4 and CO2.

Purpose of this thesis is wisdom accumulation from current area of energetic use of hydrogen and future systems. In overview is presented possible processes where dominate steam methane reforming. In main part of thesis, steam methane reforming will be analyzed and electrolysis also. Actual results will be discussed. Next part is about energetic use of hydrogen based on thermochemical properties and safety. Used of hydrogen will be divided to areas thermal generation as burner‘s section, electric generation as fuel cell‘s section, mechanical energy as combustion engine’s section and finally chemical transportation of energy. At the end will be made a promising energy systems using hydrogen as fuel which can be applied in a large scale.

京都大学 / 新制・課程博士 / 博士(人間・環境学) / 甲第23265号 / 人博第980号 / 新制||人||232(附属図書館) / 2020||人博||980(吉田南総合図書館) / 京都大学大学院人間・環境学研究科相関環境学専攻 / (主査)教授 吉田 寿雄, 教授 田部 勢津久, 教授 中村 敏浩 / 学位規則第4条第1項該当 / Doctor of Human and Environmental Studies / Kyoto University / DFAM

京都大学 / 新制・課程博士 / 博士(人間・環境学) / 甲第24711号 / 人博第1084号 / 新制||人||254(附属図書館) / 2022||人博||1084(吉田南総合図書館) / 京都大学大学院人間・環境学研究科相関環境学専攻 / (主査)教授 吉田 寿雄, 教授 田部 勢津久, 教授 中村 敏浩, 教授 田中 庸裕 / 学位規則第4条第1項該当 / Doctor of Human and Environmental Studies / Kyoto University / DFAM

Ce travail a porté sur la conversion du méthane et de l'éthanol en hydrogène par le procédé du vaporeformage en utilisant de nouvelles formulations de catalyseurs afin d'augmenter la sélectivité en produit désiré (hydrogène), de réduire la production du monoxyde de carbone (Co) et défavoriser la formation de coke. Deux familles de phases actives, à base de cuivre et de ruthénium supportés par les hydrotalcites calcinées CoₓMg₆₋ₓAl₂, ont été évaluées dans ces réactions. Pour les deux réactions, l'influence de plusieurs facteurs a été évaluée afin d'ajuster les paramètres de la réaction. Il a été démontré que les performances des catalyseurs pour les réactions du vaporeformage dépendent de la teneur en cobalt et en magnésium.Une grande teneur en cobalt améliore la réactivité catalytique. Le catalyseur 1Ru/Co₆Al₂ a présenté la plus forte activité et stabilité dans la réaction du vaporeformage du méthane parmi les autres catalyseurs industriels et préparés. Les espèces réduites de ruthénium et du cobalt ont été détectées après la réaction par DRX. La technique RPE était capable de détecter des quantités négligeables de deux types d'espèces carbonées formées lors de la réaction : du coke et du carbone. D'autre part, le catalyseur 5Cu/Co₆Al₂ a révélé la productivité la plus élevée en hydrogène dans la réaction du vaporeformage de l'éthanol. Cependant, il se désactive après quelques heures à cause de la formation du coke. Le catalyseur 5Cu/Co₂Mg₄Al₂ a montré une quantité beaucoup plus faible d'espèces carbonées sans désactiver pendant 50 heures en raison du caractère basique de la phase de l'oxyde du magnésium présente dans le support. / This work focuses on methane and ethanol conversion to hydrogen in the presence of a catalyst in order to increase the selectivity of the desired product (H₂) and reduce carbon monoxide emission and coke formation. Two kinds of active phase were used (copper and ruthenium) and impregnated on calcined hydrotalcites CoₓMg₆₋ₓAl₂ in order to be evaluated in the methane and ethanol steam reforming reactions. For both reactions, the influence of several factors was evaluated in order to adjust the reaction parameters. It has been shown that catalysts performances for the reforming reactions depend on the content of cobalt and magnesium. High cobalt content enhanced the catalytic activity. 1Ru/Co₆Al₂ catalyst presented the highest activity and stability in the methane steam reforming reaction among the other industrial and prepared catalysts even under a low GHSV and with no hydrogen pretreatment. Reduced ruthenium and cobalt were detected after the reaction by XRD. EPR technique was able to detect negligible amount of two kinds of carbonaceous species formed during the reaction : coke and carbon. On the other hand, 5Cu/Co₆Al₂ catalyst revealed the highest hydrogen productivity in the ethanol steam reforming reaction. However, it suffers from coke formation that deactivated the catalysts after few hours. 5Cu/Co₂Mg₄Al₂ catalyst showed a much lower quantity of carbonaceous species with no deactivating during 50 hours due to the basic character of the magnesium oxide phase present in the support.

Parmi les produits issus de la biomasse ou de la transformation des déchets organiques, le CO2 et le CH4 sont des intermédiaires chimiques importants qui ont de forts impacts environnementaux. En effet, ils sont les principaux gaz responsables de l'effet de serre et leur atténuation est un enjeu majeur. Une voie intéressante pour la valorisation de ces gaz est le reformage à sec du méthane (DRM), qui convertit le CO2 et le CH4 en gaz de synthèse (mélange d'hydrogène et de monoxyde de carbone). Ce mélange peut être utilisé pour plusieurs applications telles que la production de méthanol, d'éther diméthylique, d'hydrogène et des hydrocarbures liquides. Malgré cet intérêt, l'exploitation du DRM à l'échelle industrielle n'a pas encore vu le jour. La raison principale est la désactivation rapide des catalyseurs en raison des conditions sévères de fonctionnement du procédé (température élevée, dépôt de carbone). Cette thèse porte sur le développement de nouveaux catalyseurs à base de phosphate de calcium (CaP) dopés avec des métaux de transition pour la valorisation du CO2 et du CH4 en gaz de synthèse par DRM. Les CaP sont utilisés car ils possèdent des propriétés avantageuses en catalyse hétérogène comme la présence simultanée de sites acides et basiques, bonne stabilité thermique, large gamme de surface spécifique ... Dans un premier temps, des études sur les méthodes de synthèse de catalyseurs et sur la performance de différents métaux de transition (Zn, Fe, Co, Cu, Ni) ont été effectuées dans le but de sélectionner le catalyseur et sa méthode de préparation. Un réacteur à lit fixe capable de fonctionner à hautes température et pression a ensuite été testé pour un long temps de réaction afin d'évaluer correctement la performance des catalyseurs préparés. Ensuite, une étude paramétrique détaillée a été menée. L'influence des paramètres tels que le prétraitement des catalyseurs, la température (T = 400-700°C) et la pression (P = 1-25bar) de la réaction et les différents supports (hydroxyapatite, alumine) ont été étudiés. Enfin, la stabilité thermique et catalytique a été étudiée durant 300h de réaction. Les catalyseurs à base de CaP ont montré des rendements plus élevés en gaz de synthèse en comparaison aux catalyseurs commerciaux. Ces catalyseurs sont donc compétitifs dans les mêmes conditions opératoires (T = 700°C, P = 1bar, WHSV = 12272mLh-1gcat-1, t = 300h). Ce travail a montré l'intérêt des catalyseurs à base de CaP pour des processus à haute température, tel que le reformage à sec du méthane. / Among the products resulting from biomass or organic waste transformation, CO2 and CH4 are important chemical intermediates. They also have a strong environmental impact since they are primarily responsible for the greenhouse effect and their mitigation is a key issue. An attractive way of valorization of such gases is the dry reforming of methane (DRM), which converts CO2 and CH4 into syngas (mixture of hydrogen and carbon monoxide). This mixture can be used for several applications, such as the production of methanol, dimethyl ether, hydrogen and liquid hydrocarbons. Despite such interest, the exploitation of DRM on industrial scale has not emerged yet. The main reason is the rapid deactivation of the catalysts due to the severe operating conditions of the process (high temperature, carbon deposition). This thesis focuses on the development of new catalysts based on calcium phosphate (CaP) doped with transition metals for the valorization of CO2 and CH4 through DRM. Actually,CaP has advantageous properties in heterogeneous catalysis, as the simultaneous presence of acid and basic sites, good thermal stability, and wide range of surface area... Initially, a study on the catalyst synthesis methods and an investigation of the performance of different transition metals (Zn, Fe, Co, Cu, Ni) were carried out in order to select the catalyst system and the preparation method. Secondly, a fixed-bed reactor capable of operating at high temperature and pressure and for log time on stream was built and implemented during this work in order to properly evaluate the performance of the preparedcatalysts. Then, a detailed parametric study was conducted. The influence of parameters such as catalyst pre-treatment, temperature (T = 400-700°C) and pressure (P = 1-25bar) of the reaction and support (hydroxyapatite, alumina-based supports) were investigated. Finally, the catalytic stability was studied for 300h of time on stream (TOS). The CaP catalysts showing higher yields on syngas were compared to commercial catalysts. Our catalysts showed to be competitive in the same operating conditions (T = 700°C, P = 1bar, WHSV = 12272mLh-1gcat-1,TOS = 300h). This work shows the interest of CaP catalysts for high temperature process, such as dry reforming of methane.