Tesi sul tema "Méthane – Reformage à sec"
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Rakib, Abdelmajid. "Valorisation du méthane en hydrogène par reformage catalytique". Phd thesis, Université du Littoral Côte d'Opale, 2012. http://tel.archives-ouvertes.fr/tel-00828240.
Wei, Yaqian. "Production d'hydrogène à basse température par reformage à sec et reformage oxydant du méthane sur divers catalyseurs à base de nickel". Thesis, Ecole centrale de Lille, 2017. http://www.theses.fr/2017ECLI0033/document.
In order to develop a sustainable hydrogen economy, it is desirable to produce hydrogen from biogas (CH4 and CO2) or greenhouses gases (GHG). Dry reforming (DRM) and oxidative dry reforming of methane (ODRM) are promising routes to produce H2 and CO from GHG and have received much attention due environment concerns. Herein, these reactions were studied at low temperatures (600 -700 °C) over CeNiX(AlZ)OY, NiXMg2AlOY mixed oxides and Ni/SBA-15 supported catalysts. Various physico-chemical techniques were employed to characterize the catalysts, such as XRD, XPS, H2-TPR and Raman. The influences of different parameters were examined, such as reaction temperature, pretreatment in H2, Ni content, mass of catalyst and reactants concentration, in particular, at 600°C in harsh conditions (feed gases without dilution) on low mass of catalyst (10 mg). The best catalytic activity and selectivity are obtained on partially reduced catalysts at appropriate temperature. The addition of O2 increases CH4 conversion but decreases CO2 conversion, and O2/CH4 = 0.3 could be the optimized condition due to high activity, selectivity and low carbon formation. Finally, an active site involving Ni species in close interactions with other cations is proposed. It is related to a partially reduced catalyst involving anionic vacancies, O2- species, and cations, which is formed during the in situ H2 treatment or CH4 flow
Gaillard, Marine. "Reformage à sec du méthane à l’aide de catalyseurs à base de molybdène : vers la valorisation catalytique du biogaz". Thesis, Lille 1, 2016. http://www.theses.fr/2016LIL10163/document.
In the worldwide current energy situation, new pathways for renewable energy production are developed. In Europe, methanisation is an alternate way widely implemented since it produces biogas that contains CH4 and CO2. The reforming of this biogas could lead to the consumption of the two main greenhouse gases for the production of syngas (H2, CO), which could be industrially attractive for the Fischer-Tropsch process, eventually setting up a promising waste-to-liquids technology. Yet, the main hurdle regarding this reaction is the presence of sulfur in the biogas which poisons the catalysts.Thus, a set of molybdenum-based catalysts has been synthesized and tested for the dry reforming of methane. The influence of several parameters has been evaluated, such as (i) molybdenum loading, (ii) the addition of promoters (Ni, Co, CeO2 and MgO) or (iii) the use of different supports (Al2O3, ZrO2, Carbone, SiO2, MgO). The catalysts have been analyzed via several characterization techniques to establish structure/activity relationships, identify the main deactivation phenomena and conclude on the most stable and active composition in presence of H2S during the catalytic runs
Guerrero, Jesús. "Valorisation du méthane par reformage sec en régimes stationnaire et non-stationnaire sur catalyseurs à base de nickel : mise en œuvre d'un réacteur à alimentation périodique". Thesis, Lille 1, 2015. http://www.theses.fr/2015LIL10162/document.
Nowadays the society is concerned about the greenhouse effect, and the necessity to find alternative procedures and more sustainable and durable processes to obtain the products made from petroleum. The valorization of CH4 with CO2 (dry reforming) brings the advantage of consuming gases which contribute strongly to the greenhouse effect. This reaction produces H2 and CO, which jointly or separately, are the raw materials for different processes producing energy and chemicals.Ni-Ce-O and Ni-Mg-Al-O based catalysts were successfully prepared. The influence of different parameters was studied, such as the Ni loading and the reaction temperature (600°C-800°C). The main difficulties are the formation of coke leading to rapid catalyst deactivation due to the high operating temperatures and the simultaneous presence of CO2 (reactant) and hydrogen (product) which leads, by the reverse water gas shift (RWGS), to a loss in selectivity. A process which can avoid this kind of problematics consists in exposing alternately each of the reactants. Initially the solid acts as oxygen carrier reacting with methane to form carbon monoxide (1 mole) and hydrogen (2 moles). As the solid is regenerated at each cycle, the deactivation by carbon deposition is avoided. The activity and selectivity of the solid is provided by the presence of a reducible oxide (CeO2) and a metal (Ni, Co), which cannot be reoxidized under the experimental conditions ensuring the activation of methane. Different physicochemical characterizations were performed on catalysts to find correlations between the catalytic activity and properties of the solids
Li, Tong. "Etude de catalyseurs à base de carbure de molybdène pour le reformage à sec du méthane et la synthèse Fischer-Tropsch". Thesis, Lille 1, 2016. http://www.theses.fr/2016LIL10213/document.
Molybdenum carbide catalysts have been studied in dry methane reforming (DMR) and in Fischer-Tropsch synthesis (FTS). For the DMR reaction, For the DMR, different contents of Ni promoted Mo2C/Al2O3 catalysts were investigated. The results indicated nickel increased the activity and stability of Mo2C/Al2O3 catalysts. The addition of nickel promoted the re-carburization of Mo species from oxycarbide to carbides species and led to the rapid increase of activity during reaction. The different preparation methods also had a significant influence on the nickel promoted Mo2C/Al2O3 catalysts. For FTS, different supports and different promoters have been investigated for the Mo2C based catalysts. The results suggested that alumina supported catalyst exhibited higher light olefins selectivity. Increasing the potassium contents lead to a decreased in t CO hydrogenation activities and also inhibited the water gas shift reaction. However, it obviously increased the olefins selectivity and carbon chain growth properties. At last, DMR under pressure and FTS in the presence of CH4 or CO2 were investigated. The results showed that an increase in pressure led to high carbon deposition over the catalyst surface and the addition of CH4 and CO2 in the syngas decreased the CO hydrogenation activity and affect the products distribution
Barros, Braulio Silva. "Vaporeformage et reformage à sec du méthane sur les précurseurs catalytiques LaNiO3/α-Al2O3 et La2NiO4/α-Al2O3 préparé par combustion assistée par microondes". Strasbourg, 2009. http://www.theses.fr/2009STRA6028.
Nickel catalysts have been used in steam or dry reforming of methane to obtain syngas. Usually, high conversion levels are obtained by these catalysts; however, the deactivation by carbon deposition is still a problem to be solved. Several approaches have been used to minimize this problem, outstanding in the last years the use of oxides with perovskite-type structures and/or related structures. The catalytic precursors LaNiO3/-Al2O3 and La2NiO4/-Al2O3 were prepared by microwaves-assisted self-combustion using urea or glycine as fuel. Additionally, the same systems were prepared using nitrates impregnation and Sol-gel method. Obtained powders were characterized before and after catalytic tests by XRD, BET, TPO, TPR, SEM and TEM. The catalytic precursors prepared by self-combustion with glycine presented conversion results in agreement with the thermodynamic data for both reforming reactions. In the other side, the prepared catalysts with urea and by impregnation showed high conversion levels in lower temperatures, indicating the occurrence of the reaction of methane cracking. The accomplished analyses by Temperature-programmed oxidation profiles and transmission electronic microscopy confirmed in these catalysts the formation of carbon nanotubos. Deposits of carbon were not detected in the prepared samples with glycine. X-ray diffraction of the tested catalysts suggests that the partial of the oxides La-Ni is responsible for the good aging and resistance to the carbon deposition. The partial reduction promotes the control of the size and a better dispersion of the metallic nickel particles
Catalisadores a base de níquel suportado em óxidos não-redutíveis, como alumina, têm sido amplamente empregados nas reações de reforma a vapor ou a seco (CO2) do metano para obtenção de H2 ou gás de síntese (H2 + CO). Normalmente, altos níveis de conversão são obtidos por estes catalisadores, entretanto, a desativação por deposição de carbono ainda é um problema a ser solucionado. Diversas abordagens têm sido empregadas no intuito de minimizar este problema, dentre as quais tem se destacado nos últimos anos a utilização de óxidos com estrutura perovskita e/ou estruturas relacionadas. Paralelamente,o uso de metodologias de síntese mais rápidas, fáceis, aplicáveis em escala industrial e que permitam o controle das características microestruturais destes catalisadores, pode em conjunto, prover a solução para este problema. Os precursores catalíticos LaNiO3/-Al2O3 e La2NiO4/-Al2O3 foram preparados pelo método de autocombustão assistida por microondas usando uréia ou glicina como combustível. Adicionalmente, os mesmos sistemas foram preparados pelos métodos de impregnação úmida de nitratos e sol-gel para efeito de comparação. As amostras preparadas foram testadas nas reformas a seco e a vapor do metano, sendo avaliados os respectivos níveis de conversão, rendimento e/ou seletividade, como também a resistência à deposição de carbono, durante o tempo sob fluxo de reagentes na temperatura de reação. As amostras foram calcinadas a 800 oC (LaNiO3/-Al2O3) e 1000 oC (La2NiO4/-Al2O3), para obtenção das fases desejadas. Os pós-obtidos foram caracterizados antes e após os testes catalíticos por difração de raios-X, medidas de área superficial especifica, oxidação e redução à temperatura programada, microscopia eletrônica de varredura e de transmissão. A cristalização da fase LaNiO3 foi confirmada em todas as amostras de composição LaNiO3/ - Al2O3, calcinadas a 800 oC. Para as amostras de composição La2NiO4/ - Al2O3 a fase La2NiO4 foi obtida por autocombustão com glicina sem calcinação posterior. Para todos os outros casos a calcinação a 1000 oC foi necessária. Os perfis de redução à temperatura programada das amostras preparadas por combustão com glicina apresentaram picos de redução a elevada temperatura (900 oC), sugerindo a dissolução do alumínio sobre os óxidos redutíveis contendo níquel. O mesmo foi observado em menor proporção para as amostras preparadas por combustão com uréia e sol-gel. Os precursores preparados por autocombustão com glicina apresentaram resultados de conversão em acordo com a termodinâmica de ambas as reações de reforma. Por outro lado, os catalisadores preparados com uréia e por impregnação mostraram altos níveis de conversão em temperaturas mais baixas (> 90 % a partir de 600 oC), indicando a ocorrência da reação de quebra do metano (CH4 ® C + 2H2). Por sua vez, as analises realizadas por oxidação a temperatura programada e microscopia eletrônica de transmissão, confirmaram a formação de depósitos carbonáceos em significativa quantidade e na forma de nanotubos de carbono de paredes múltiplas. Depósitos de carbono não foram detectados nas amostras preparadas com glicina. Analises de DRX dos catalisadores testados sugerem que a redução parcial e não total dos óxidos La-Ni é responsável pelo bom desempenho e resistência à deposição de carbono. A redução parcial, neste caso relacionada a metodologia de preparação, promove o controle do tamanho e uma melhor dispersão das partículas de níquel metálico, além de permitir uma interação mais forte entre a espécie ativa e a superfície do suporte que contém átomos de níquel
Jabbour, Karam. "Combined and dry reforming of methane on new Ni0/diatoms and mesoporous Ni0/alumina catalysts". Thesis, Paris 6, 2016. http://www.theses.fr/2016PA066345.
Dry and combined (steam and dry) reforming of methane are two processes for the conversion of CH4 and CO2 gases emitted from the decomposition of biomass into gaseous mixtures with controllable H2:CO (syngas) molar ratios: value of 1 in the case of dry or around 2 for combined reforming. Nickel based catalysts are found as promising candidates for these reactions displaying high intrinsic activity, lower cost and wider availability than noble metal based materials but deactivating by sintering and/or coke deposition. Stabilization and confinement (occlusion) of small metallic Ni0 nanoparticles within structured (i.e. Al2O3 and SiO2) porous oxide frameworks is one of the recent methods to overcome the deactivation in dry reforming but has not yet been considered under harsh combined reforming (high T and steam) conditions. The main objective of this work was to synthetize, characterize and test new stable catalysts for reforming reactions: (i) based on natural, cheap and widely available macroporous silica diatom oxide as support for Ni- and (ii) synthetized by various methods for control of dispersion and stability inside mesoporous alumina and silica. One-pot mesoporous alumina being the most stable catalysts in combined reforming, some modifiers (MgO or CaO) were added in order not only to get stable catalysts but also to minimize coke formation during long-term (40h) combined reforming reaction
Jabbour, Karam. "Combined and dry reforming of methane on new Ni0/diatoms and mesoporous Ni0/alumina catalysts". Electronic Thesis or Diss., Paris 6, 2016. http://www.theses.fr/2016PA066345.
Dry and combined (steam and dry) reforming of methane are two processes for the conversion of CH4 and CO2 gases emitted from the decomposition of biomass into gaseous mixtures with controllable H2:CO (syngas) molar ratios: value of 1 in the case of dry or around 2 for combined reforming. Nickel based catalysts are found as promising candidates for these reactions displaying high intrinsic activity, lower cost and wider availability than noble metal based materials but deactivating by sintering and/or coke deposition. Stabilization and confinement (occlusion) of small metallic Ni0 nanoparticles within structured (i.e. Al2O3 and SiO2) porous oxide frameworks is one of the recent methods to overcome the deactivation in dry reforming but has not yet been considered under harsh combined reforming (high T and steam) conditions. The main objective of this work was to synthetize, characterize and test new stable catalysts for reforming reactions: (i) based on natural, cheap and widely available macroporous silica diatom oxide as support for Ni- and (ii) synthetized by various methods for control of dispersion and stability inside mesoporous alumina and silica. One-pot mesoporous alumina being the most stable catalysts in combined reforming, some modifiers (MgO or CaO) were added in order not only to get stable catalysts but also to minimize coke formation during long-term (40h) combined reforming reaction
Izquierdo, Colorado Armando. "Reforming of model biogas mixtures at moderate temperatures over Ni-containing catalysts". Electronic Thesis or Diss., Sorbonne université, 2019. http://www.theses.fr/2019SORUS147.
The increasing concern about the possible dramatic effects of greenhouse gases emissions to our atmosphere, is leading to propose sustainable alternatives, aiming either capture/storage or capture/utilization of CO2. Among the different technologies, dry reforming of methane has attracted much attention in the past decades because it consumes two of main greenhouse gases (CO2 and CH4) and convert them into useful chemical building blocks. In this context, biogas is another CH4-rich source, containing also non-negligible amounts of CO2, therefore, it can be upgraded into hydrogen and/or synthesis gas, as a renewable carbon source for the synthesis of alternative and carbon-neutral liquid fuels. Nickel-containing catalysts have been considered for methane reforming and its partial oxidation. This is due to its high activity and low cost. However, the sintering and carbon formation, producing catalyst deactivation. Thus, this PhD research focuses on proposing new strategies towards increasing the activity, selectivity and stability of Nickel-containing catalysts for their application in the reforming of biogas model mixtures. These strategies include the use of different supports aiming at increasing their interaction with the active nickel-phase and improving its dispersion and stability. Moreover, different approaches for the deposition of this Ni-phase and its activation have been investigated. The results were correlated with multiple characterizations, such as Brunauer-Emmett-Teller (BET), X-ray diffraction (XRD), H2-temperature programmed reduction (H2-TPR), NH3 and CO2-temperature programmed desorption (CO2-TPD, NH3-TPD) and Transmission electron microscopy (TEM)
Chamoumi, Mostafa. "Nouvelle génération de catalyseurs supportés par valorisation d'un résidu d'enrichissement (procédé UGS) d'une scorie de TiO2 : le catalyseur Ni-UGSO appliqué au reformage de méthane". Thèse, Université de Sherbrooke, 2017. http://hdl.handle.net/11143/10379.
Liu, Xiu. "Production d'hydrogène par reformage à sec de méthane sur catalyseurs au Ni à base de CeO2, CeO2 modifiée avec Zr ou Al, et nano-matériaux Mg-Al-O". Electronic Thesis or Diss., Centrale Lille Institut, 2021. http://www.theses.fr/2021CLIL0032.
The demand for hydrogen, as a chemical product and as energy is increasing, but the main hydrogen production methods are unsustainable and not environmentally friendly. Hydrogen production from renewable resources (such as biogas mainly composed of CH4 and CO2) is required. Dry reforming of methane (DRM) is a promising method to produce H2 and CO from greenhouse gases. In this thesis, Ni-based CeNiXOY, CeZr0.5NiXOY, CeAl0.5NiXOY, and AlMg2NiXOY catalysts are studied in dry reforming of methane reaction. The effect of reaction temperature, Ni content, in situ H2 pretreatment, mass of catalyst, calcination, and CO2/CH4 ratio are studied. Moreover, long duration stability tests are reported on some chosen samples. The optimized catalytic performance associated with resistance to carbon formation is obtained on partially reduced catalysts. Various physicochemical characterizations are used to analyze the properties of the catalysts, such as XRD, Raman, XPS, and H2-TPR. Some chosen catalysts are also characterized after DRM reaction to analyze their evolution. Finally, an active site involving Ni species in close interactions with other cations is proposed. It is related to a partially reduced catalyst involving anionic vacancies, O2- species, and cations
Tanios, Carole. "Caractérisation, évaluation de la toxicité du biogaz issu de déchets ménagers et valorisation par reformage catalytique". Thesis, Littoral, 2017. http://www.theses.fr/2017DUNK0474/document.
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
Hallassi, Manel. "Elaboration, caractérisation et mesure d'activité catalytique et/ou photocatalytique sur des matériaux oxydes binaires et/ou ternaires". Electronic Thesis or Diss., Université de Lille (2022-....), 2023. http://www.theses.fr/2023ULILR032.
Bimetallic (NiM (M=Cr, Fe), ZnM (M=Cr, Fe)) and trimetallic (NiZnM (M=Cr, Fe)) double lamellar oxide (DLO) catalysts with nominal compositions of Ni/M = 2 or 3 and Ni+Zn/Fe and Ni+Zn/Cr = 3, respectively, were prepared from the double lamellar hydroxides (DLH) using the co-precipitation method. The structure, texture and reducibility of the obtained catalysts were monitored by several physicochemical techniques: XRD, Raman, BET, XPS, TPR and SEM-EDX. The catalytic properties were evaluated for the dry reforming of methane reaction (CH4 + CO2 à 2H2 + 2CO). The structural study by XRD and Raman shows that the hydrotalcite structure was present at room temperature and stable up to 250 °C. The interspaces decreased as the temperature increased, with a lattice parameter and interspaces of 3.018 Å and 7.017 Å, respectively. The solids decompose completely into oxide after calcination at 500 °C. NiO, ZnO and spinel phases (NiM2O4 and ZnM2O4 M = Cr or Fe) were observed in NiM, Zn (M = Cr, Fe) and Cr2O3 were detected for chromium formulations. The NiFe and ZnFe catalysts show low activity in the DRM reaction over the entire temperature range studied. In contrast, the Cr-containing systems showed interesting CH4 and CO2 conversions and excellent H2 selectivity at low reaction temperatures. CH4 and CO2 conversions of 18-20% with H2/CO of about 0.7 at temperatures as low as 500°C, but transient behavior and deactivation were observed at higher temperatures or at long reaction times. The sequence was attributed to the stabilization of Ni metal particles formed during the reduction of the NiO phase due to the presence of NiCr2O4, paving the way for the use of these materials in periodic or looping processes for low temperature methane reforming
Liu, Hongrui. "CO2 Chemical Utilization through Dry Reforming of Methane : Development of Non-Noble Metals Catalysts Supported on Natural and Synthetic Clays". Thesis, Sorbonne université, 2018. http://www.theses.fr/2018SORUS480.
The development strategy of “growth-at-any-cost” has not been applied to the current development with the increased attention of various countries to environmental issues. But the dependence on fossil fuels such as petroleum will be still high in a short period of time based on the consideration of economic and social development. Thus, the focus on the production of hydrogen, syngas or other products using CO2 and/or CH4 that has attracted more attention in chemical products is the process of dry reforming of methane. Thus, this research focuses on proposing new supports loaded with different promoters to enhance the catalytic selectivity and stability of nickel-based catalysts for dry reforming of methane, and analyze the catalytic performance of prepared catalysts by associating temperature effects with multiple characterizations such as Brunauer-Emmett-Teller, X-ray diffraction, and CO2-temperature programmed desorption. First, different promoters with nickel are impregnated on natural clay or Fe/Cu-modified clay from Tunisia. Second, the synthetic clay derived catalysts are prepared by co-precipitation method to research the influences of structure on the DRM. In the end, the catalysts having the same composition as excellent Ni-hydrotalcite derived catalysts are further synthesized by ball milling to compare the effect of rotational speed and preparation
Caudal, Jean. "Simulation numérique du reformage autothermique du méthane". Phd thesis, Ecole Centrale Paris, 2013. http://tel.archives-ouvertes.fr/tel-00862538.
Rêgo, de Vasconcelos Bruna. "Phosphates-based catalysts for synthetic gas (syngas) production using CO2 and CH4". Thesis, Ecole nationale des Mines d'Albi-Carmaux, 2016. http://www.theses.fr/2016EMAC0004/document.
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
Rijo, Gomes Sérgio. "Production d'hydrogène par reformage dans la boucle EGR". Poitiers, 2010. http://theses.edel.univ-poitiers.fr/theses/2010/Rijo-Gomes-Sergio/2010-Rijo-Gomes-Sergio-These.pdf.
This research work is devoted to the study of catalytic reforming of exhaust gas recirculation (REGR) for gasoline engines. The aim of this technology is to improve fuel economy and to reduce pollutant emissions, keeping practically the same engine. A lot of catalysts, containing 1wt% of Rh, supported on alumina doped by ceria, Al(Cex) and/or baryum, AlBa(Cex) or on zirconia doped by rare earth oxides ZLNY(Cex), were characterized and evaluated in REGR conditions for high (580°C) and l ow (450°C) temperatures. The Rh(1wt%)/ZLNY(Cex) catalysts present the best activity and/or stability, the Rh(1wt%)/ZLNY catalyst being the most selective for hydrogen production. From the best catalytic formulation, two fundamental studies were carried out in REGR conditions in order to understand the role of the co-reactants and the surface species on the catalyst performance and deactivation, and to determine the reaction scheme for the main reactions (steam reforming, dry reforming and methane formation)
Alvarenga, Marinho Andre Luiz. "Development of catalytic process for biogas upgrading : study of structure and oxygen mobility on Ni and Pt nanoparticles encapsulated catalysts". Thesis, Poitiers, 2020. http://www.theses.fr/2020POIT2272.
Dry reforming of methane (DRM) is a catalytic process able to convert the biogas generated from biomass degradation into syngas, which has many industrial applications. However, coke formation and metal sintering are the main drawbacks to upgrade this technology to an industrial scale. This work evaluates the effect of Ni encapsulation in two different structures: embedded nanoparticles and distributed nanoparticles over mesoporous support. Results showed that Ni embedded in ceria improved the resistance to sintering along the reduction at high temperature (800 °C) and led to a higher metal-support interaction compared to impregnated catalyst. Doping ceria with Zr inhibited the growth of CeO2 and Ni clusters in embedded catalysts and increased the oxygen mobility as revealed by oxygen isotopic exchange experiments. The doping with Gd and Sm did not enhance thermal stability on the material and the sintering is still observed. The nature of metal exchanging Ni by Pt did not affect the promotional effects of encapsulation in embedded structures. Ni-based mesoporous mixed CeO2-Al2O3 oxide catalysts prepared by one pot Evaporation Induced Self Assembly (EISA) presented small metallic Ni particles (< 5 nm). Different behavior occurs with CeO2-Al2O3 oxide prepared by EISA method when Ni is post-impregnated because of the presence of isolated larger Ni particles which promotes the decomposition of CH4. Finally carbon deposits were not detected over embedded Ni@CeZrO2 after 24 h of reaction and meosoporous 10Ni- CeO2-Al2O3 after 72 h of reaction and, therefore, these catalysts presented promising results in this work for biogas upgrading process by dry reforming of methane reaction
Vernoux, Philippe. "Reformage interne progressif du méthane dans les piles à combustible à oxyde électrolyte solide". Grenoble INPG, 1998. http://www.theses.fr/1998INPG0155.
Hafsaoui, Julien. "Membrane duale de reformage et de filtration pour la production d'hydrogène par réaction de craquage de méthane". Phd thesis, Paris, ENMP, 2009. http://tel.archives-ouvertes.fr/tel-00425050.
In a context of rarefaction and increasing of prices of fossil energetic resources, it is necessary to diversify the energetic offer. Hydrogen seems to be one of the most promising vectors, although technological matters associated to its production slow down its development. In this context, the present work aims at elaborating a system able to produce pure hydrogen from hydrocarbon, and in particularly from methane. It is constituted of three membranes, which specific roles are reforming, separation and retitution of molecular hydrogen. The first membrane is porous and is made of a cermet BaCe0. 85Y0. 15O3-α / nickel. The second one is dense and is elaborated either simply from BaCe0. 85Y0. 15O3-α, or from the same cermet as the first membrane, depending whether the system operates in a galvanic or in a non-galvanic mode. The last one is of the same nature and morphology as the first one. The three membranes are fabricated and coupled one with the others by the process called co-tape-casting in organic solvent followed by a step of co-sintering. More precisely, on the free surface of the first membrane a layer of a mixture of powders Xj / Ni, where Xj and Ni are respectively the support and the catalyst for methane cracking reaction (Xj = CeO2, Silica, Nanodiamonds, zeolithes,…), is deposited via a humid route. Then, by feeding with methane this system, with for example the presence of the highly efficient couple CeO2/Ni, the production of hydrogen is made possible and deposited carbon atoms form nanotubes with Ni particles at their tops, which are then always in the methane flux, and which then do not suffer from deactivation. Hydrogen enters then in the porosity of the first membrane where it is oxidized when meeting with triple phases boundaries. In a non-galvanic system, protons and electrons can go through the second membrane, following the percolating proton and ion conducting paths, to reach the third membrane. In a galvanic system, electrons are transported toward the third membrane via an external circuit, which imposes a voltage. At the third membrane triple phase boundaries, electrons and protons recombine to form pure molecular hydrogen. These two systems galvanic and non galvanic have been designed and fabricated, and the motivation that has led to the choice of the materials used was given at each step of the process. Thanks to the comprehension of the different phenomena taking place during operating conditions, a rather optimized process leading to a system of production and purification of hydrogen was realized. Finally, a numeric model was developed, in order to tailor the influence of all the different parameters that may influence the performances of the object
Leroi, Pascaline. "Etude du reformage du méthane en gaz de synthèse sur catalyseurs à base de carbure de silicium". Université Louis Pasteur (Strasbourg) (1971-2008), 2003. http://www.theses.fr/2003STR13080.
The work which was carried out for this PhD thesis was based on the use of nickel supported on silicon carbide (SiC) catalysts for methane steam reforming (SR) and methane partial oxidation (POx). Concerning the SR process, the effect of several reaction parameters (temperature, pressure, oxidizing/reducing agent) and that of the parameters which are specific to catalysts were optimized. The post-catalytic characterizations showed that the catalysts present an increased resistance towards coke deactivation and almost no deactivation has been observed as a function of time on stream. Regarding the POx process, comparison tests demonstrated the advantage of SiC, a conductive material, over alumina, which is an insulating material. At the start of the reaction, the conversion of methane observed on alumina-based catalyst largely exceeds the thermodynamic value which means that temperature runaway has occured in the catalyst bed. This is not the case with SiC catalysts due to its high thermal conductivity which allows the rapid heat evacuation from the catalyst bed. The hot spot formation significantly alters the alumina-based catalyst morphology whereas the morphology of the SiC-based catalyst was completely retained. Post-reaction characterizations showed a great difference not only in the nature but also in the amount of carbon formed on both supports, i. E. Filamentous carbon on the alumina-based catalyst and amorphous carbon on the SiC-based catalyst
Kroll, Vincent. "Reformage du méthane en gaz de synthèse par le dioxyde de carbone : développement de catalyseurs, mécanisme et cinétique". Lyon 1, 1996. http://www.theses.fr/1996LYO10230.
Daoura, Oscar. "Towards anti-coking and anti-sintering Ni@Silica based catalysts for the dry reforming of methane". Electronic Thesis or Diss., Sorbonne université, 2019. http://www.theses.fr/2019SORUS679.
Dry reforming of methane is a process for the conversion of CH4 and CO2 into “syngas”, a gaseous mixture of H2 and CO (with a molar ratio value of 1) that can serve as feedstock for the production of liquid fuel by the mean of Fischer-Tropsch procedure. Nickel-based catalysts are promising candidates for this reaction displaying high activity, lower cost and wider availability than noble metal-based materials but deactivating by sintering and/or coke deposition. Stabilization of Ni0 nanoparticles within siliceous supports either by confinement and/or by improving their dispersion and interaction with the support are among the best and the less expensive methods to overcome the deactivation in dry reforming which represents the main objective for this work. Here, new stable nickel-based catalysts were synthesized, characterized and tested in dry reforming. Three main issues were examined: (i) Testing the efficiency of new mesoporous supports (mesocellular silica foams) using different nickel precursors (salt or colloidal form) incorporated by impregnations or pH adjustment assisted one-pot methods, (ii) designing highly dispersed nickel-based mesoporous monoliths through an original sol-gel method (iii) controlling the nickel size, dispersion and therefore its interaction with the support onto non-porous silica carriers by the mean of phyllosilicates. Monoliths of the SBA-15 type incorporating Ni0 by a one-pot method, and Ni0 obtained through the reduction of nickel phyllosilicates turned out to be the most stable and efficient catalysts
Safariamin, Maryam. "Valorisation catalytique du biogaz (CH4 +CO2) par reformage à sec : étude des propriétés physico-chimiques et catalytiques de solides à base de Tuthénium et Cuivre". Littoral, 2010. http://www.theses.fr/2010DUNK0281.
In this study, the reaction of methan reforming with CO2 was investigated in the presence of catalysts based on ruthenium and copper deposited on Al2O3, CeO2-Al2O3 binary oxides and mixed oxides from hydrotalcite precursors. The aim of this work is reduction of greenhouse gases (CH4 + CO2) to obtain the synthesis gas (H2 + CO) to be used for various applications including clean energy. The catalysts were prepared by dry impregnation and characterized by various physico-chemical methods (BET, XRD, FT-IR, UV-VIS, TPR, DTA/TG and EPR) to identify correlations between their physico-chemical properties and their catalytic performance. Influence of different conditions and solids pretreatment on the catalytic activity have been studied. Hydrogen production is strongly influenced by the nature of the metal phase and the support used. It is noteworthy that both types of catalysts (Ru and Cu/support) were not similar activities for the reaction studied. The ruthenium-based catalysts are much more active than those based on copper. Hydrotalcites have proved effective for the reforming reaction, but they produce a large amount of coke which deactivates the catalyst easily. Among all catalysts are studied, the solid containing 5% RuO2 on the support of CeO2-Al2O3 binary oxides was the most active and most stable. The high reactivity of this catalyst is associated to good dispersion of ruthenium species and to the very low amount of coke on the catalyst observed after 14 days of aging
Haag, Stéphane. "De la synthèse d'une membrane composite nikel/céramique permsélective à l'hydrogène au réacteur membranaire : Application au reformage du méthane". Université Louis Pasteur (Strasbourg) (1971-2008), 2003. http://www.theses.fr/2003STR13203.
The objective of this work was to develop composite inorganic membranes based on nickel or palladium supported on a porous ceramic for high temperature hydrogen separation. These membranes were used in a membrane reactor for the dry reforming of methane in order to shift the chemical equilibrium towards the production of hydrogen and carbon monoxide. The metal layers were deposited on a tubular alumina support by electroless plating. The Ni and the Pd layers are 1 micron thick. The hydrogen permeation tests were done for high temperatures. The Pd/ceramic membrane is permselective to hydrogen and the H2/N2 separation factor (single gas) is 60 at 400ʿC with a transmembrane pressure difference of 1 bar. With a gas mixture, the H2/N2 separation factor is 13. This membrane is not completely dense and the transport mechanism of hydrogen through the Pd layer is mixed : solution-diffusion through the metal bulk and surface diffusion through the defects of the film. However, an embrittlement of the palladium layer under hydrogen atmosphere was observed at 500ʿC. The Ni/ceramic membrane is stable until 600ʿC, its permselectivity to hydrogen increases with the temperature. The use of a sweep gas can provide a H2/N2 separation factor (mixture) of about 25. The main diffusion mechanism is surface diffusion through the pores. Both membranes are not catalytic. Thus, some catalysts composed of nickel and cobalt supported on MgO, SiO2 or Al2O3 were prepared. These systems allow to reach theoretical limits of conversion calculated for a conventional fixed bed reactor. In the membrane reactor, an enhancement of the methane conversion (15-20%) is observed with both membranes due the selective removal of hydrogen during the reaction. The Ni/ceramic membrane more stable, more permeable and as selective as the palladium one is a brand new material for high temperature hydrogen separation
Baudouin, David. "Design, préparation et caractérisation de catalyseurs pour le reformage du méthane par le dioxyde de carbone à basse température". Thesis, Lyon 1, 2011. http://www.theses.fr/2011LYO10234.
Low temperature dry reforming (LT-DR), < 600 °C, coupled with membrane technology to overcome thermodynamically low conversion, has drawn attention as an alternative approach to industrial 850-950°C operating conditions. The aim of this work has then been to design and develop nickel-based catalysts that are active and stable under LT-DR. In that context, we developed methods to prepare well-dispersed Ni nanoparticles on silica and to modify silica support, addressing detailed characterization at each step with various techniques (H2 & CO2 chemisorption, TPX, TEM, XRD, EXAFS, IR and NMR spectroscopy). We studied the effect of particle size, preparation methods (organometallic, colloidal… approaches), metal dopants and poisons for the support and the nanoparticles on the activity, selectivity and stability of the catalyst in LT-DR. Overall, we showed that supported Ni particles are indeed good candidate in LT-DR by comparison with noble metals, which are the reference catalysts for the corresponding High-Temperature DR. In particular, small Ni particles supported on lanthanum doped silica surface provided the best performances, while the use of pure lanthanide oxide or mixed oxide supports led to limited activity in Low-temperature DR. Finally, using a colloidal approach to synthesize Ni nanoparticles has proven to be very efficient and versatile, allowing one to deposit nickel particles with remarkable properties on any supports
Bailly, Nicolas. "Mise au point d'une cellule de SOFC haute performance alimentée en méthane pur sans dépôt de carbone". Phd thesis, Université de Grenoble, 2012. http://tel.archives-ouvertes.fr/tel-00825651.
Bassil, Siréna. "Procédé propre de production de chaleur et d'électricité à partir d'un biogaz produit à l'échelle domestique : exemples de matériaux catalytiques de reformage du méthane". Thesis, Lyon 1, 2014. http://www.theses.fr/2014LYO10055.
The catalytic reforming of methane into hydrogen, for direct operation of Solid Oxide Fuel Cells (SOFCs) on methane, was studied on anode materials such as NiO/CeO2, NiO-Y2O3-ZrO2 and La0.8Sr0.2TiO3+δ. The first group of catalysts was synthesized by two methods: the impregnation technique both in aqueous and organic media (commercial and laboratory made CeO2 and Y2O3-ZrO2), and also using sol-gel process. Lanthanumtitanium oxide host structure doped with strontium was prepared both by co-precipitation and sol-gel process. The method of preparation has an important effect on the physico-chemical properties of the synthesized catalysts and affects consequently both their catalytic performances in methane reforming and their resistance to poisoning by carbon deposition. In order to limit carbon formation on the catalytic surface and to increase the lifetime of catalysts during the catalytic reforming of methane, ceria supported nickel based-catalysts were doped with magnesium oxide (forming MgO-NiO solid solution) as well as with lanthanum oxide (La2O3-NiO). The obtained results show that the effect of promotion of NiO active phase by MgO and La2O3 decreases carbon deposition but also the catalytic performances. Physico-chemical properties and catalytic performances of NiO-Y2O3-ZrO2 (Ni-YSZ) prepared by the sol-gel process were compared with those of commercial (Aldrich and Jülich) materials having the same composition. The experimental results showed that materials synthesized by the sol gel method are more active in methane steam reforming than commercial catalysts while sol gel and commercial samples show similar performances in methane dry reforming. Amounts of graphitic carbon, although being higher for sol gel samples compared to commercial ones, remain low (< 2%). This carbon deposit provokes only a slight decrease of catalytic performances of sol gel prepared materials in methane dry reforming, probably by decreasing the number of active sites
Sauvet, Anne-Laure. "Etude de nouveaux matériaux d'anode pour pile à combustible à oxyde solide (SOFC) fonctionnant sous méthane". Université Joseph Fourier (Grenoble), 2001. http://www.theses.fr/2001GRE10096.
Kaydouh, Marie-Nour. "Confinement effect of Nickel in mesoporous silica-based catalysts for syngas production by reforming of methane with CO2". Thesis, Paris 6, 2016. http://www.theses.fr/2016PA066425/document.
Although economically and environmentally advantageous, the methane dry reforming process using supported nickel based catalysts still faces problems of active phase (a transition metal) sintering and of carbon deposition, which result in catalytic activity loss. This thesis is focused on the study of the confinement effect of nickel in mesoporous silica-based catalysts for syngas production by reforming of methane with CO2. In this study, the samples were characterized by N2 sorption, XRD, TEM/SEM, TPR, in addition to Raman, XPS, TPH/MS, TGA/MS for the spent catalysts. The results indicate that a well-structured mesoporous support with high surface area and large pore volume is important for better dispersion and stabilization of the active phase inside the porosity. The mesoporous SBA-15 silica support (prepared in large quantity), composed of elongated grains, appear to be suitable for the purpose. Moreover, it is demonstrated that the formation of small nickel particles well-confined inside the pores favors carbon resistance. This can be achieved by applying hydrothermal treatment to the support, using two solvents method for Ni deposition, using direct reduction of uncalcined samples, adding Rh in small quantities or promoting with Ce, provided that Ni and Ce are in interaction
Tabet, Aoul-Benyoucef Amel. "Élaboration et caractérisation de nouveaux cermets d'anodes pour piles à combustible de type SOFC". Besançon, 2008. http://www.theses.fr/2008BESA2032.
This thesis deals with the development of new anode cermets for SOFC type fuel cell, operating directly under methane. Two major aspects are taken into account: the chemical composition of the anode material and its microstructure. To do so, cermets based metals such as nickel, copper and cobalt and a fully yttria stabilized zirconia as ceramic matrix were prepared by atmospheric plasma spraying (APS), under optimizated conditions. The choice of used materials became so as to meet the requirements for an anodic application, namely an enough porosity to enable gases permeability, good ionic and electronic conductive properties and good chemical and mechanical compatibilities with the electrolyte. The anode materials must also have a fine thermal stability at high temperatures and good electrochemical and electrocatalytic properties toward oxidation and fuel internal reforming reactions. The different morphological and structural characterisations revealed porous deposits, formed by the succession of metallic and ceramic lamellas, with safeguarding the initially identified crystalline phases for feedstock powders. The expressed electrical conductivity measurements versus the temperature for different cermets seemed to be like that of pure metals despite the presence of the ceramic matrix. Moreover some cermets unveiled a good thermal stability at a temperature of 800°C. Thus, anode cermets prepared under optimized APS conditions, with the accurate chemical composition, present the appropriate morphology and microstructure for an anodic application, in SOFCs operating directly under methane at temperatures around 800°C without risk of major damage
Mbodji, Mamadou. "Conception et dimensionnement de réacteurs-échangeurs microstructurés pour la production de gaz de synthèse par vaporeformage du méthane". Thesis, Université de Lorraine, 2013. http://www.theses.fr/2013LORR0256/document.
Steam Methane Reforming (SMR) of natural gas is characterized by generation of an excess of steam and their low thermal efficiency resulting in a very large device with important heat losses. One of the possible keys to make this process more profitable is to optimize heat transfer by changing the reactor design. A microstructured heat exchanger reactor has been retained. It enables to have fast heat and mass transfers and therefore allow increasing catalytic activity. However, this change in production technology must be accompanied by the development of highly active catalysts (MgAl2O4) that enable to reach high methane conversion (80%, 20 bar, 850°C) at low residence time (150 ms). The concept feasibility and catalysts performance have been validated on one channel in industrial process conditions. Then, a detailed model for acquisition of reaction kinetics has been developed and validated from experimental catalytic tests. For heat exchanger reactor design, two modeling approaches have been developed: by considering that the catalyst is highly active and enables to reach instantaneous equilibrium conversion on the coated catalytic walls of the reactor and by tacking the measured kinetics. Simulation of these models by considering technical constraints on the design enabled to find channel characteristic dimensions, heat power needed and the optimum number of channel which determine the heat exchanger reactor volume. Two fast methods for preliminary design of heat-exchanger reactors have been developed. By using heat exchanger reactor, it is possible to suppress steam excess generation and to reduce syngas production cost
Fedotov, Alexey. "Conversion of methane and carbon dioxide on porous catalytic membranes". Thesis, Vandoeuvre-les-Nancy, INPL, 2009. http://www.theses.fr/2009INPL099N/document.
This study reports the development of a new process to convert methane and carbon dioxide (dry methane reforming - DMR) into valuable products such as syngas from non-oil resources. The practical interest is to produce syngas from carbon containing exhaust industrial gases. This process uses membrane catalytic systems (MCS) that support heterogeneous catalytic reactions in gaseous phase in ceramic micro-channels. The active surface of the catalysts formed inside the micro-channels is low in term of area, but it is characterized by a high value of the catalyst surface/volume ratio, which induces a high efficiency of heterogeneous catalysis. The SMC are formed from alkoxy derivatives and precursor metal complex containing between 0.008 and 0.055% by weight of nano-components mono-and bimetallic active distributed evenly in the channels. For systems [La-Ce] -MgO-Ti02/Ni-Al and Pd-Mn-Ti02/Ni-Al, productivities of 10500 and 7500 l/h · dm3 membr. were respectively obtained by RSM at 450°C with a composition of syngas H2/?? ranging from 0.63 to 1.25 and a conversion rate of 50% with a CH4/CO2 (1/1) feed. Thus the CMS is an order of magnitude more efficient than a fixed bed reactor of the same catalyst. The MDR is initiated by the oxidation of CH4 by structural oxygen of metal oxides available on the surface, and the CO2 reacts with the finely divided carbon arising from the dissociation of CH4. A catalytic synergy has been demonstrated for the system Pd-Mn. This CMS, having 108 pores per cm² of surface, can be considered as a set of nano reactors. Thus this new approach is very promising for industry (synthesis of olefins, uses of biomass)
Karam, Leila. "New routes of preparation of active and stable mesoporous Ni-alumina based catalysts for methane dry reforming and CO2 methanation". Electronic Thesis or Diss., Sorbonne université, 2019. https://accesdistant.sorbonne-universite.fr/login?url=https://theses-intra.sorbonne-universite.fr/2019SORUS163.pdf.
Dry reforming of methane (DRM) is a process that converts CH4 and CO2 gases into syngas, a gaseous mixture of H2 and CO. Ni based catalysts proved to be suitable for the reaction due to their good activity, wider availability and lower cost than noble-based materials. However, these catalysts are not stable due to Ni sintering and coke deposition. In this thesis we developed two different synthesis routes of mesoporous Ni-Al2O3 based catalysts that can occlude Ni inside the pores achieving high activity and stability in DRM. A set of complimentary physicochemical techniques was systematically applied to thoroughly investigate the materials properties at all steps of preparation and activation. The first approach embraces synthesis of mesoporous Ni-Mg-Al2O3 materials by one-pot EISA strategy. Results demonstrate that 15 wt% Mg (optimum loading) based sample contribute to high and homogenous dispersion of both Ni and Mg, preserving ordered mesoporous Al2O3 walls. The good structural and textural characteristics in addition to the enhanced basicity reinforce activity and stability. The second method involves synthesizing new mesoporous Ni-Al2O3 materials using metal-organic framework as sacrificial template. This procedure results in small Ni nanoparticles homogeneously dispersed and stabilized within the high surface area support resisting sintering and inhibiting carbon nanotubes formation during reforming reaction. Based on catalytic tests completed by thermodynamics calculations, the synthesized materials proved to be eficient not only for dry reforming of methane, but also for CO2 methanation reaction and dry reforming of waste pyrolysis products
Périllat-Merceroz, Cédric. "Titanates de structures pérovskite et dérivées : influence des éléments constitutifs et de la dimensionnalité sur les propriétés d’anode SOFC". Thesis, Lille 1, 2009. http://www.theses.fr/2009LIL10130/document.
SOFC anode materials working under methane have to display excellent catalytic properties for fuel oxidation without coke formation. The influence of the structure dimensionnality on catalytic and electrochemical properties was studied. After synthesis of the materials by a Pechini-type method and structural characterization by means of X-ray, neutron and electronic diffraction, the catalytic activation of samples toward methane steam reforming was pursued in slightly humidified methane (CH4:H2O=10:1). Electrical conductivity measurements were carried out in temperature and at low oxygen partial pressure. Then, the electrochemical response of these materials was evaluated by impedance spectroscopy using symmetrical and complete cell under humidified H2, under or without a current bias. Among all tested compounds, the best candidate is the x=0.80-member of the LaxSr1-xTiO3+d family, which displays a lamellar structure exhibiting long range ordered over-stoichiometric oxygen. Low electrical performance when compared to 3D compounds (about 10-2 S.cm-1 at 1073K in Ar/H2(2%)), is compensated by very high catalytic and electrochemical activity
Hajjaji, Noureddine. "Analyse de cycle de vie exergétique de systèmes de production d’hydrogène". Thesis, Vandoeuvre-les-Nancy, INPL, 2011. http://www.theses.fr/2011INPL002N/document.
Considered as the future energy carrier, hydrogen appears to be the miracle solution to overcome the current energy crisis and environmental problems. This can be possible only by solving all the problems associated with its life cycle (production, distribution, storage and final use).Due to the large number of environmental impacts generated during hydrogen production, the complexity of their evaluation and the possible interactions among them the use of environmental assessment methods is necessary. The Exergetic Life Cycle Assessment (ELCA) approach was chosen as the most useful tool for hydrogen production scenarios investigation. It compares hydrogen production systems in order to identify which one is more eco-efficient and recognizes their opportunities for environmental improvement. Eight scenarios for hydrogen production were studied by the ELCA approach. These scenarios are essentially based on reforming techniques of fossil methane, biomethane and bioethanol. The results show that the hydrogen produced by fossil methane scenarios, a mature and widely used technique, are the largest consumers of abiotic resources and emitters of greenhouse gases (GHG). The use of biomethane as hydrogen source presents an interesting solution. The environmental profile of a hydrogen ex-bio-methane can be made even more attractive solution by improving anaerobic digestion system with on-site reforming process. The use of bio-ethanol produced from wheat as a hydrogen source has large environmental impacts. In fact, these processes are characterized by large eutrophication and acidification potentials in addition to their emissions of large amount of greenhouse gases (GHG). However, bio-ethanol can be a sustainable and renewable source for hydrogen production on condition that it is produced by environmentally friendly manners
Kaydouh, Marie-Nour. "Confinement effect of Nickel in mesoporous silica-based catalysts for syngas production by reforming of methane with CO2". Electronic Thesis or Diss., Paris 6, 2016. https://accesdistant.sorbonne-universite.fr/login?url=https://theses-intra.sorbonne-universite.fr/2016PA066425.pdf.
Although economically and environmentally advantageous, the methane dry reforming process using supported nickel based catalysts still faces problems of active phase (a transition metal) sintering and of carbon deposition, which result in catalytic activity loss. This thesis is focused on the study of the confinement effect of nickel in mesoporous silica-based catalysts for syngas production by reforming of methane with CO2. In this study, the samples were characterized by N2 sorption, XRD, TEM/SEM, TPR, in addition to Raman, XPS, TPH/MS, TGA/MS for the spent catalysts. The results indicate that a well-structured mesoporous support with high surface area and large pore volume is important for better dispersion and stabilization of the active phase inside the porosity. The mesoporous SBA-15 silica support (prepared in large quantity), composed of elongated grains, appear to be suitable for the purpose. Moreover, it is demonstrated that the formation of small nickel particles well-confined inside the pores favors carbon resistance. This can be achieved by applying hydrothermal treatment to the support, using two solvents method for Ni deposition, using direct reduction of uncalcined samples, adding Rh in small quantities or promoting with Ce, provided that Ni and Ce are in interaction
Swirk, Katarzyna. "Design of new catalysts for chemical CO2 utilization". Thesis, Sorbonne université, 2019. http://www.theses.fr/2019SORUS367.
Reforming of methane, belonging to the Carbon Capture and Utilization technologies, is considered an attractive route for syngas production. Double-layered hydroxides (DLHs) with Ni, Al2O3, MgO components were reported to have promising properties. Promotion with yttrium, zirconium or cerium also positively influence the catalytic performance. Thus, the goal of this PhD thesis was to evaluate the catalytic behavior of Ni/Mg/Al DLHs promoted with Y, and Zr or Ce in dry reforming of methane (DRM), partial oxidation of methane (POM), partial oxidation combined with methane reforming (CRPOM), and tri-reforming of methane (TRM). The catalysts were characterized by XRD, XRF, N2 sorption, TPR-H2, TPD-CO2, H2 chemisorption, TEM, HRTEM, TGA and Raman spectroscopy and tested in TPSR from 600 to 850°C, and at 700°C for 5h. In DRM, the Y promotion increased Ni dispersion and SBET, especially with 2 wt.%. Zr and Y co-impregnation resulted in the YSZ phase formation leading to better stability. The Zr and Y introduction during co-precipitation step increased the Ni dispersion and the total basicity, similarly as for Ce and Y promoted materials. In the oxidative reforming, HTNi and HTNi-Y2.0 were tested. In POM, both were active and stable with H2/CO≈2.0. CRPOM tests showed higher CH4 conversion, but lower for CO2 as compared to DRM. Addition of O2 in the gas feed greatly contributed to the C removal. The carbon formation was inhibited when CO2/H2O=1 during TRM tests. However, with CO2/H2O=0.5, a high amount of C was formed, and the structural stability of Y-catalyst was negatively influenced as periclase was transformed into hydroxides
Phan, Thanh Son. "Élaboration, caractérisation et mise en œuvre d’un catalyseur dans le reformage du biogaz en vue de la production d’hydrogène vert". Thesis, Ecole nationale des Mines d'Albi-Carmaux, 2020. http://www.theses.fr/2020EMAC0007.
Biogas production worldwide is increasing steadily. The combustion to generate heat and electricity, and the biomethane production for injection into the city gas grid are currently the two major industrial applications of biogas. Current research on biogas valorization targets the production of high-value products such as hydrogen for transportation. This is the main objective of the VABHYOGAZ3 project funded by ADEME, which aims at deploying the production of H2 from biogas in the Tarn department, France. Biogas steam reforming, adopted by the industrial partners of the VABHYOGAZ3 project, is a commonly used process in the industry to reform natural gas, but it is a highly energy-consuming process. This PhD thesis aims to develop efficient catalysts for the Dry Reforming of Methane (DRM: conversion of CH4 and CO2 into syngas - mixture of CO and H2) and for the Tri-Reforming of Biogas (Tri-RB: conversion of CH4, CO2, H2O and O2 into syngas). The ultimate goal was to optimize the energy efficiency of the overall process of H2 production through the reforming of biogas, which is essential to make the process economically viable. In fact, DRM and Tri-RB catalysts usually have the problem of catalytic deactivation due to coke deposition and thermal sintering at high temperature (> 700 °C). Obtaining an efficient catalyst under severe conditions of DRM and Tri-RM is crucial for the deployment of these processes at large industrial scale. First, a study on the thermodynamics of the overall processes for H2 production via the reforming of biogas was carried out. Mass and energy balances of these processes were also obtained by ASPEN simulation. Then, various nickel-based catalysts supported on hydroxyapatite (HAP) and on hydroxyapatite substituted with Mg (Mg_HAP) were prepared and characterized. HAP-based supports are considered to be new catalytic materials which have suitable properties for heterogeneous catalysis, in particular for high temperature processes such as DRM and Tri-RM. In this study, HAP supports having the Ca/P molar ratio of 1.55, 1.67 and 1.75, and Mg_HAP (substitution of 2.2, 5.8 and 8.5 % of Ca with Mg) have been synthesized. These supports were doped with 5 wt.% of Ni by incipient wetness impregnation method. These catalysts were evaluated for both DRB and Tri-RB reactions in a fixed bed reactor. A parametric study on the influence of operating conditions including temperature, total pressure, biogas feeding rate, and molar ratio of steam to methane (S/C) and oxygen to methane (O/C), has been performed. The objective was to compare and identify the best catalysts and the best operating conditions. Mass balances have been established experimentally. Catalytic deactivation has been discussed and evidenced. Finally, the stability of the best catalysts was studied for a long reaction time of 150-300 h, and catalyst regeneration was also performed. This work shows that Ni-based catalysts supported on HAP or on Mg_HAP are competitive to the best catalysts identified in the literature. This work also confirms the interest of the use of new HAP-based supports in heterogeneous catalysis and particularly in high temperature processes
Cesário, Moisés Rômolos. "Vaporeformage catalytique du méthane : amélioration de la production et de la sélectivité en hydrogène par absorption in situ du CO2 produit". Phd thesis, Université de Strasbourg, 2013. http://tel.archives-ouvertes.fr/tel-00999401.
Bobin, Alexey. "Methane reforming by carbon dioxide over metal supported on nanocrystalline mixed oxides : mechanism and transient kinetics for relating catalysts structure and performance". Thesis, Lyon 1, 2014. http://www.theses.fr/2014LYO10164/document.
Oxygen bonding strength, mobility and reactivity in nanocrystalline Ln-doped ceria-zirconia (Ln=La, Gd, Pr, Sm) with supported Pt, Ni, Ru were studied by state-of-the-art techniques such as isotopic exchange in static and flow reactors with 18O2 and C18O2, O2 TPD, H2 and CH4 TPR, pulse microcalorimetry and TAP reactor. Bulk oxygen mobility is found controlled by a rearrangement of Ce and Zr cations coordination sphere with doping as well as by fast oxygen migration along Pr3+/Pr4+ cationic chains. Surface and near-surface oxygen mobility appears controlled by a strong metal-support interaction with incorporation of metallic ions into surface layers and domain boundaries. In realistic feeds, the catalytic activity in dry reforming of methane correlates with oxygen mobility, required to prevent coking and metal sintering.Transient kinetic studies (non steady-state and SSITKA) allowed us to propose a bi-functional reaction mechanism corresponding to independent redox steps of CH4 and CO2 activation. The rate- limiting step is shown to be the irreversible activation of CH4 on metal sites, while CO2 dissociation on reduced sites of oxide supports proceeds much faster (being reversible for the steady-state surface) followed by a fast oxygen transfer along the surface/domain boundaries to metal sites where CH4 molecules are transformed to CO and H2. The CH4 selective conversion into syngas would involve strongly bound bridging oxygen species with heat of desorption ::600-650 kJ/mol O2. For optimized formulations, Ni+Ru clusters could be involved in CO2 activation via facilitating C-O bond breaking in the transition state, thus increasing the rate constant of the surface reoxidation by CO2, while strongly bound carbonates behave as spectators. For Pt/PrCeZrO, an additional fast route to syngas would occur on Pt ions with participation of weakly bound carbonates stabilized by neighboring Pr4+ ions. Such specificity makes this system highly promising for methane oxi-dry reforming, especially on structured corundum supports for short contact time compact reactors, well adapted to stranded and limited gas resources
Di, Giuliano Andrea. "Synthesis, characterization and industrial applicability of combined sorbent-catalyst materials for sorption enhanced steam methane reforming". Thesis, Strasbourg, 2017. http://www.theses.fr/2017STRAF065/document.
Sorption enhanced steam methane reforming (SESMR), steam methane reforming (SMR) with in situ CO2 sorption by a solid sorbent, can lead to a sustainable exploitation of natural gas to produce H2. (CSCM). This thesis, as a part of ASCENT (Advanced Solid Cycles with Efficient Novel Technologies) project, deals with Ni-CaO-mayenite combined sorbent-catalyst material for SESMR, to study the effect of Ni fraction, its precursor salt (Ni nitrate or Ni acetate), and free CaO fraction. ICP AES, XRD, BET and BJH methods, SEM EDS, TEM EDS, TPR and TGA were used to characterize synthesized materials. Their reactivity was evaluated by tests in a packed bed microreactor, which served also as a screening tool to choose the most promising materials. Their industrial applicability was assessed by multicycle SESMR/regeneration tests in an automated packed bed bench scale rig
Croissant, Baptiste. "Intensification du procédé de vaporeformage du gaz naturel : fonctionnalisation catalytique d'échangeurs-réacteurs". Thesis, Limoges, 2018. http://www.theses.fr/2018LIMO0115.
The Steam Methane Reforming (SMR) process is still today the most profitable industrial synthesis process of hydrogen. The efficiency of this technique is however facing intrinsically technical limitations due to the design of production units. In order to intensify the global process, exchangers-reactors are under investigation at AIR LIQUIDE. Thanks to recent progresses in metallic additive manufacturing, new compact equipment can be designed. Structures made of millimetric channels allow optimizing heat and mass transfers. New catalyst architecture design needs to be developed to reach high conversion rates despite extreme low contact times in such devices. Stable and highly active rhodium-based catalysts supported on spinel MgAl2O4 have been prepared in this aim. The impact of rhodium loading, properties of supports, as well as thermal treatments have allowed us understanding active phase and support interactions. Catalyst properties under SMR conditions have been linked to active phase morphologies. Functionalization of exchangers-reactors channels through a dip-coating technique has been detailed in this thesis. The formulations of suspensions of washcoat have been optimized thanks to rheological behavior characterizations to achieve very low viscosities. A procedure to deposit homogeneous coatings with controlled thicknesses on the internal channels has been validated on a pilot structure. These new intensified exchangers-reactors have been successfully tested for methane conversion during several hundred of hours
Homsi, Doris. "Steam reforming of methane ans ethanol over CoₓMg₆₋ₓAl₂, Ru/CoₓMg₆₋ₓAl₂ and Cu/CoₓMg₆₋ₓAl₂ catalysts". Phd thesis, Université du Littoral Côte d'Opale, 2012. http://tel.archives-ouvertes.fr/tel-00920778.