WorldCat Identities

Unité de catalyse et chimie du solide (UCCS)

Overview
Works: 220 works in 247 publications in 2 languages and 247 library holdings
Roles: Other, Degree grantor
Publication Timeline
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Most widely held works by Unité de catalyse et chimie du solide (UCCS)
Valorisation de l'hydrogène pour la réduction des NOx en moteur diesel by N'Guessan Anita Kouakou( Book )

2 editions published in 2011 in French and held by 2 WorldCat member libraries worldwide

This thesis aims to investigate the feasibility of coupling a NOxTrap with a SCR catalyst. The efficiency of such a system running in sequential conditions depends on the extent of NH3 formed during the purge of the NOxTrap. The impact of Rh for further optimization has been investigated. An evaluation in real exhaust conditions on a driving bench showed that it is only possible to form NH3 during the purge of a NOxTrap by injecting extra reducing agent via a reformate mainly composed of CO and H2. Once formed NH3 can be stored on the SCR catalyst placed downstream and then react with NOx when the catalyst is exposed in lean conditions during the storage phase. The efficiency of this system depends not only on the purge duration and but also on the temperature. In fact, the performance of this system is linked to the quantity of NH3 formed during the purge of a NOxTrap and the NH3 storage capacity of the SCR catalyst. Similar trends were observed on a micro-reactor at the lab-scale. Further IR operando study showed that nitrates and nitrites are stored on alumina and mostly on barium oxide during the storage phase. Their ability to react during the purge follows a process in two stages when the purge duration is long enough. The selectivity in N2, N2O and NH3 depends on the quantity and on the nature of the reducing agents. H2 is probably the best one with a high efficiency in NOx reduction even at low temperature providing selectivity enhancement in NH3. However, the presence of CO was found to inhibit the storage and the reduction of NOx at low temperature. Above 250°C the formation of isocyanates on Al2O3 and BaO takes place and would produce NH3 via hydrolysis
Catalyseurs à base d'or pour la réduction catalytique sélective des oxydes d'azote par les hydrocarbures provenant de sources mobiles by Duy Luan Nguyen( Book )

2 editions published in 2012 in French and held by 2 WorldCat member libraries worldwide

Nowadays, emissions of atmospheric pollutants from mobile sources such as nitric oxides (NOx) are submitted to more stringent regulations especially within the next Euro 6 which will be implemented in Europe at the beginning of 2014. Up to now commercialized technologies available for the abatement of NOx from lean burn engine (running with a large excess of oxygen) are not capable to remove simultaneously NOx and particulates in lean atmosphere. This study is essentially focused on the NOx conversion to nitrogen via the Selective Catalytic Reduction by using hydrocarbons (HC-SCR) in representative Diesel exhaust gas conditions. This technology is more feasible than the Lean-NOx trap and Urea-SCR systems. Supported gold catalysts on alumina have been developped for the replacement of Pt and Pd less selective. Particular attention was paid to the thermal stability under reaction conditions at 500°C. Among the different synthesis protocols investigated (Deposition-precipitation, Anionic exchange), it was found that the anionic exchange method leads to the best compromise with a larger operating window after ageing. In addition, the reduction of NOx to nitrogen seems structure sensitive, the largest particles being more active than the smallest ones usually thermodynamically instable at high temperature. In this context, such behavior should be profitably used for further practical developments since post-combustion catalysts essentially run at rather high temperature. The second part of this study was dedicated to the modification of Au/Al2O3 catalysts after silver incorporation. Different strategies implemented for Ag incorporation have been examined. Coprecipitation and grafting lead to the formation of bimetallic particles with homogeneous distribution of gold and silver especially via the coprecipitation method. Strong interaction between Au and Ag with further modification of their electronic and adsorptive properties leads to strong deactivation. On the other hand, the segregation of both metals on alumina preserving their intrinsic properties improves the catalytic performances especially after ageing. The influence of different operating condition has been examined showing the best compromise when gold is successively impregnated on Ag/Al2O3
Oxydation de COV catalysée par des matériaux à porosité hiérarchisée (Nb-TiO2) et de type tamis moléculaire octaédrique (cryptomelane) : effet des métaux nobles Pt et Pd by Manuel Dario Franco Finol( Book )

2 editions published in 2012 in French and held by 2 WorldCat member libraries worldwide

Volatil Organic Compounds are primary pollutants whose concentration in air must be reduced due to their harmful effects in the environment and human health. Catalytic oxidation of VOCs is a promising way of treating these pollutants. In this context, the oxidation of n-butanol and / or toluene were studied in the presence of two families catalytic materials. The first material was a new material with a hierarchical porosity (micro-, meso- and macroporous) based on niobium doped TiO2. In particular, it was found that Nb and Pt addition has an effect on the structural, textural, and redox properties of the Nb-TiO2 mixed oxide. The tuning of all these properties has led to an optimal formulation for catalytic removal of n-butanol at low temperatures. The second materialemployed was a manganese oxide type mesoporous cryptomelane. These fibrous materials, doped with noble metals in very small quantities, were very active in the n-butanol and toluene oxidation due to the improvement of their redox properties at low temperatures. The most remarkable results were obtained in the study of the oxidation of a VOC mixture. This is caused by a synergistic effect obtained from the oxidation of toluene which could be oxidized at very low temperatures never reported before
Indirect ammoxidation of glycerol into acrylonitrile via the intermediate acrolein by Carsten Liebig( Book )

2 editions published in 2012 in English and held by 2 WorldCat member libraries worldwide

Suite au caractère fini des réserves de charbon, pétrole et gaz, nous sommes obligés de trouver des alternatives renouvelables pour substituer les ressources fossiles comme source d'énergie et matière première pour l'industrie chimique. Parmi les nombreuses exemples ou la biomasse est déjà utilisé comme alternative aux ressources fossiles, on peut notamment citer le biodiésel. Ce dernier est produit à grande échelle par la transesterification de l'huile végétale. Cependant, le glycérol est formé comme sous-produit inévitable qui doit être valorisé pour augmenter la compétitivité du procédé. Parmi les différentes possibilités de valorisation, la déshydratation pour donner l'acroléine est le plus prometteur. Ce dernier peut ensuite être converti en acrylonitrile par ammoxidation catalytique. Dans ce projet, les deux réactions - déshydratation et ammoxidation - ont d'abord été étudiés séparément puis ensuite combinés en utilisant un réacteur de type tandem. Pour l'étape de déshydratation, un catalyseur à base de WO3/TiO2 été utilisé. Pour l'ammoxidation, les catalyseurs ont été choisis parmi les oxydes métalliques à base d'antimoine, de fer, de vanadium et de molybdène. Notamment le catalyseur à base de Sb-Fe-O montre des bonnes performances, c'est pourquoi le ratio Sb/Fe été étudié plus en détail. La présence de la phase FeSbO4 est directement corrélée à la sélectivité en acrylonitrile. De plus, on constate une augmentation de la sélectivité en cours de la réaction, ce qui s'explique avec la formation de FeSbO4 in operando. Après l'optimisation des paramètres clefs à l'aide d'un plan d'expérience, les deux réactions ont été combinées. Le rendement maximal obtenu est de 40%
Nouveaux supports mésostructurés pour la catalyse d'hydrotraitement by Andres Miño( Book )

2 editions published in 2012 in French and held by 2 WorldCat member libraries worldwide

Les catalyseurs d'hydrodésulfuration (HDS) sont de type CoMo/Al2O3. L'amélioration de leurs performances catalytiques peut être envisagée par l'amélioration des propriétés du support industriellement utilisé, Al2O3-[gamma]. La synthèse d'alumines mésoporeuses en présence de structurants utilisées comme supports de catalyseurs d'HDS a été étudiée. Deux voies de synthèses des alumines sont présentées : sol-gel (SG) et modification post synthèse (PSM). Ces voies de synthèses ont permis d'obtenir des alumines avec des propriétés texturales améliorées par rapport aux alumines conventionnelles. Ces supports ont été imprégnés par une solution de (Co2Mo10O38H4)Co3. L'étape d'imprégnation des alumines SG et PSM entraîne une modification plus ou moins importante des propriétés texturales. Une voie de synthèse directe (VD) de catalyseurs HDS, basée sur la synthèse des alumines PSM mais avec l'ajout des précurseurs de la phase active pendant la préparation de l'alumine, a également été développée. La synthèse VD permet de contourner le problème d'effondrement de la texture du support lors de l'imprégnation et permet aussi d'augmenter considérablement la teneur en phase active. Les résultats catalytiques en HDS du thiophène des catalyseurs de chaque famille ont mis en évidence des performances très intéressantes en comparaison avec des catalyseurs classiques. Une série de catalyseurs de chaque famille ont été testés en HDS du gazole. Les performances catalytiques obtenues sont dans la plupart des cas supérieures à celle obtenue pour un catalyseur référence et pour les catalyseurs les plus performants se sont avérées inédites pour des catalyseurs HDS préparés sans ajout ni modifiant
Synthèse d'oxydes d'actinides en milieu chlorure fondu : études structurales et mécanismes réactionnels by Jean-François Vigier( Book )

2 editions published in 2012 in French and held by 2 WorldCat member libraries worldwide

The study developed in this thesis concerns actinide oxides synthesis for nuclear fuel refabrication, and more specifically, the actinide (III) precipitation in molten salt LiCl-CaCl2 (30-70%mol) salt at 700°C using wet argon sparging. First, this conversion method is described for neodymium (III) and cerium (III) coconversion. The conversion rates are around 99.9%, and the obtained powders contain mixed oxychloride Ce1-xNdxOCl as main component, with a small amount of mixed oxide Ce1-xNdxO2-0.5x for the high cerium ratio. A second oxychloride CeIV(Nd0.7Ce0.3)IIIO3Cl is obtained in specific conditions and in very low quantity. The structure of this oxychloride is described in this study. The partially oxidative property of the conversion method induces the oxidation of a part of cerium (III) to oxidation state (IV). In the case of uranium (III) conversion by wet argon sparging, all the uranium is oxidized and give the oxide UO2 as single compound. The conversion rate for this element is over 99.9% in the molten chloride, but significant amount of uranium is lost by volatilization during the conversion. Finally, the U(III) and Pu(III) coconversion study shows the highest precipitation sensitivity of uranium (III) in comparison with plutonium (III), responsible of a successive conversion of the two elements, giving an oxide mixture of UO2 et PuO2 with quantitative conversion rate. Surprisingly, the conversion of Pu(III) in the same conditions led to a mixture of PuO2 and PuOCl, characteristic of a partial oxidation from Pu (III) to Pu (IV), in contrast with coconversion of U(III)-Pu(III)
Synthèse des carbures d'U-Pu : influence des précurseurs et mécanismes réactionnels de la carbothermie de systèmes lanthanides et actinides by Alan Handschuh( Book )

2 editions published in 2010 in French and held by 2 WorldCat member libraries worldwide

Dans le cadre des réacteurs de génération IV, et plus particulièrement pour les réacteurs à neutrons rapides à caloporteur gaz (RNR-G) ou sodium (RNR-Na), les combustibles carbures mixtes d'uranium et de plutonium (U,Pu)C1+x sont envisagés du fait de leurs bonnes propriétés thermiques (conductivité thermique et température de fusion) et de leur densité en atomes lourds élevée. La réduction carbothermique d'oxydes simples d'uranium, UO2, et de plutonium, PuO2, sous vide primaire ou sous argon selon la réaction UO2 + PuO2 + (3+x)C --Vide primaire/Argon→ (U,Pu)C1+x + 2CO est la voie de référence pour la synthèse de ces carbures mixtes.Afin de répondre au jalon fixé en 2012 sur la faisabilité de fabrication des carbures, l'étude du mécanisme de carbothermie est une des voies de R&D, pour (i) mieux comprendre la formation des différentes phases carbures (monocarbure MC, sesquicarbure M2C3 (avec M = (U,Pu)) et dicarbure UC2), (ii) limiter la volatilisation d'espèces plutonifères.Le présent mémoire décrit (i) une méthode qualitative, basée majoritairement sur des analyses DRX, appliquée à la résolution du mécanisme de carbothermie d'oxydes co-broyés à base de lanthanides (CeO2 et Nd2O3) et (ii) une méthode quantitative, basée sur la résolution des équations de conservation de la matière, pour déterminer le mécanisme détaillé de la synthèse de carbures mixtes (AnC - An2C3) par réduction carbothermique d'oxydes co-broyés (UO2 et PuO2). De plus, afin de limiter la volatilisation du plutonium lors de la carbothermie, l'utilisation d'oxydes mixtes (U,Pu)O2 obtenus par co-précipitation oxalique a été envisagée. Par ailleurs, des précurseurs ont été synthétisés par un procédé similaire de la co-précipitation oxalique pour (i) simplifier la synthèse des carbures mixtes et (ii) améliorer l'homogénéité des poudres de carbone et d'oxydes mixtes dans le but d'augmenter la cinétique et/ou de diminuer la température de la carbothermie
Innovative Keggin-type polyoxometalate-based catalysts for selective oxidation of isobutane into methacrylic acid by Fangli Jing( Book )

2 editions published in 2012 in English and held by 2 WorldCat member libraries worldwide

Selective oxidation of isobutane supplies a simply and friendly to environment way to produce methacrylic acid. The Keggin-type polyoxometalates-based catalysts (NH4)3HPMo11VO40 (APMV) are used to catalyze the reaction as their controllable acidity and redox properties. But the low surface area restricts the catalytic performances. In this work, we tried to prepare the catalyst with high surface and study the effects of physochemical properties on catalytic performance.APMV were firstly supported on commercial SiO2, SBA-15 and ZrO2/SBA-15 and Cs3PMo12O40 (CPM). The surface area of catalysts increased after supporting, while the thermal stability were strongly depended on the support. Acidity played a significant role in activating the C-H bonds. The sample APMV/CPM showed the strongest acidic strength and further gave the best conversion of isobutane (15.3%) and maximum yield (8.0%) of the desired products. The content of APMV on CPM was then optimized. The partial degradation of catalyst was still observed. The V was expelled from Keggin unit under reaction conditions by surface analysis and reduced by isobutane. The Cs species were enriched on the surface. The sample 40APMV/CPM contained the maximum amount of acidic sites and gave the best catalytic performances. It also displayed good stability in 132 h run. The mixed salts Csx(NH4)3-xHPMo11VO40 were prepared to study the effects of surface Cs species. The porosity showed obvious difference as Cs content changed, as well as the acidity and redox properties. Cs element is favor to prevent V expelling from primary structure. Finally the optimization experiments in the range of Cs number from 1.7 to 2.5 was suggested
Crystal chemistry of coordination polymers based on uranyl and mixed uranyl - lanthanide carboxylates by Ionut Mihalcea( Book )

2 editions published in 2012 in English and held by 2 WorldCat member libraries worldwide

This thesis work concerns the synthesis, crystal structural study and thermal behavior of coordination polymers type uranyl and mixed uranyl-lanthanide aromatic carboxylates. Using a series of 7 aromatic carboxylate ligands, more than 25 new uranyl (so-called Uranyl-Organic Framework or UOF) and mixed uranyl-lanthanide coordination polymers have been synthesized and described in this manuscript. Some of the ligands have proven to be very prolific such as the isophthalic acid, which is present in 10 coordination polymers and with others (such as terephthalic acid) only one complex could be isolated. Some of the obtained phases contain typical monomeric or tetrameric SBUs and others possess unique features such as octanuclear SBU with an edge sharing CCI (U=O-U), linear trinuclear SBU or polymeric SBU delimiting large tunnel systems. The synthesis of all these phases conducted to a better understanding of the hydrothermal reactions and the influence of different parameters over the final reaction product. For each of the phases obtained pure the thermal behavior and thermal stability have been studied. These experiments offer a better understanding of the relation between the structure of the initial complex, the thermal degradation conditions and the nature of final oxide. Also for these phases the fluorescence emission spectra were recorded, offering information about the influence of different ligands or different type of SBUs over the typical uranyl spectrum
Optimisation de catalyseurs pour la synthèse Fischer-Tropsch à partir de biosyngaz by Aurore Butel( Book )

2 editions published in 2012 in French and held by 2 WorldCat member libraries worldwide

The work exposed in this manuscript concerns the preparation of monometallic and bimetallic catalysts containing cobalt and iron supported on alumina and silica for the synthesis Fischer-Tropsch. The catalysts denoted xCoyFe/Al2O3 or SiO2 have a total mass content of 10% for various values of the Co/Fe ratio (x and y = 0; 2.5; 5; 7.5; 10 and x+y = 10%). Thus, these catalysts were prepared by wetness impregnation and were characterized at different stages of their preparations by various physicochemical and spectroscopic techniques of characterization. The major part of this study concerns the germination of the oxides phases and the genesis of the active phases of mixed materials. The samples monometallic represent the solid references for this study. From decompositions of XANES and XPS spectra, we proposed the presence of a CoFe alloy on mixed catalysts after calcination for the low cobalt contents. A better dispersion is observed for iron compared with cobalt whatever the support used. Moreover, on the alumina support, iron and cobalt are better dispersed with lower crystallite sizes. The originality of this work consists with the Operando study, which allowed to confirm the characteristic of our mixed materials CoFe. Indeed, the latter, have a low sensitivity of sintering of the cobalt metal particles, contrary to materials monometallic. These mixed materials present an intermediate activity compared with those of monometallic materials for the Fischer-Tropsch reaction
Deactivation modeling of cobalt Fischer-Tropsch catalysts in different reactor configurations by Majid Sadeqzadeh( Book )

2 editions published in 2012 in English and held by 2 WorldCat member libraries worldwide

La désactivation reste un enjeu important lors de la synthèse Fischer-Tropsch, car il limite la vie des catalyseurs, ainsi que leurs productivités catalytiques. Elle peut être liée à certains mécanismes selon la littérature. Le frittage a été proposé comme la source principale de désactivation initiale, et avec le cokage comme phénomène responsable de la désactivation à long-terme dans ce travail. Le but de cette thèse est de développer les modèles mécanistiques capables de prédire le changement d'activité catalytique des catalyseurs FT à base de cobalt avec le temps. Dans la première étape, le changement des propriétés physico-chimiques des particules avec le temps est considéré. Un modèle de frittage est développé, qui inclut l'effet d'accélération de l'eau par formation d'une couche d'oxyde de cobalt à la surface. Ce mécanisme nous permet de lier l'agglomération des particules à certaines conditions opératoires, notamment le rapport molaire de H2O/H2. Nous avons aussi développé un mécanisme pour l'empoisonnement des sites catalytiques par dépôt de carbone pour la désactivation à long-terme. Ce mécanisme permet d'évaluer le changement de fraction des sites libres avec le temps, ainsi que les fractions molaires de CO, H2, et H2O.Ces deux modèles microscopiques sont ensuite intégrés dans les modèles des réacteurs à lit fixe et slurry pour coupler les propriétés des catalyseurs et l'activité catalytique. L'effet des conditions opératoires sur la taille des cristallites, la fraction des sites actifs et la conversion sont considérés. Les modèles sont ensuite employés dans les réacteurs de laboratoire pour s'accorder avec les résultats expérimentaux
Design of efficient catalysts for hydrogenation of carbon oxides to alcohols and olefins by Jingjuan Wang( Book )

2 editions published in 2012 in English and held by 2 WorldCat member libraries worldwide

Développement de perovskites stables pour la décomposition catalytique de N2O à haute température : application aux traitements d'effluents provenant d'ateliers de production d'acide nitrique by Yihao Wu( Book )

2 editions published in 2012 in French and held by 2 WorldCat member libraries worldwide

This manuscript is dedicated to the development of thermally stable perovskites (ABO3) for the abatement of N2O from nitric acid plants. N2O is currently formed from the incomplete combustion of ammonia to NOx on deactivated Pt-Rh gauzes at high temperature (T = 900°C). In this temperature range, the use of reducing agents is not required but thermally stable and selective catalysts must be developed for the decomposition of N2O. Catalytic performances were evaluated in real exhaust gas composition from ammonia burner. Improved structural properties and catalytic activities were achieved by partial substitution of cobalt by iron in the B sites. Tuning the surface composition was also realized from the synthesis of non-stoichiometric materials. It was found that slight La-deficient perovskites can significantly minimize the deactivation under operating conditions usually due to the surface La enrichment. Different strategies were further implemented to develop the density of active sites and enhance the intrinsic activity. It was found that the structural properties of LaCo0.8Fe0.2O3 previously optimized are destabilized after dispersion as nano-sized crystallites on CexZr1-xO2 probably due to a strong interaction. Subsequent decomposition into segregated single oxides and intercalation of La3+ cations into the framework of CexZr1-xO2 leads to a loss of activity. On the other hand, Pd incorporation into the framework of LaCoO3 and subsequent steam-induced structural reconstructions lead to Pd redispersion with significant improvements in terms of activity and stability
Formaldehyde catalytic oxidation over mesoporous manganese based materials by Jhon Jhon Quiroz Torres( Book )

2 editions published in 2012 in English and held by 2 WorldCat member libraries worldwide

La qualité de l'air intérieur est une préoccupation majeure de notre société. Le formaldéhyde (HCHO) est un polluant atmosphérique important et présent dans divers environnements intérieurs comme la maison, le bureau et l'industrie. L'oxydation catalytique complète du formaldéhyde est une voie prometteuse pour convertir ce polluant en produits inoffensifs. Les catalyseurs à base d'oxydes de métaux de transition sont décrits comme les plus prometteurs. Parmi ces oxydes, ceux à base d'oxydes de manganèse sont peu coûteux, non toxiques et peuvent être efficaces pour convertir le formaldéhyde à basse température. Ce travail vise à développer des catalyseurs mésoporeux à base d'oxydes de manganèse pour l'élimination catalytique à basse température du formaldéhyde. Des oxydes de manganèse mésoporeux contenant des teneurs variables en cérium ont tout d'abord été obtenus par activation chimique (traitement acide). L'optimisation de la synthèse du matériau mésoporeux sous atmosphère contrôlée a ensuite conduit à l'obtention d'une mésostructure lamellaire d'oxyde de manganèse. Le délaminage de cet oxyde, après calcination, a produit un oxyde de manganèse ayant des propriétés texturales très intéressantes et redox grandement améliorées. Le catalyseur le plus actif a pu oxyder complètement HCOH en CO2 et H2O à 110 °C. Finalement, des hydrotalcites à base de Mg, Mn et Al, activées par ultrasons, ont été synthétisées pour être employées en tant que précurseurs d'oxydes mixtes de manganèse de grandes surfaces spécifiques. L'effet de l'apport des ultrasons et de la composition en éléments du matériau (Mg/Mn) sur les propriétés structurales, texturales, basiques et catalytiques des oxydes mixtes a plus particulièrement été étudié
Etude de l'activité catalytique de nanoparticules métalliques supportées en réacteur microfluidique de taille caractéristique micronique : application en oxydation sélective by Jamal Ftouni( Book )

2 editions published in 2012 in French and held by 2 WorldCat member libraries worldwide

In this manuscript, the potential of microfluidics, the science of fluids through micrometric channels, are exposed in the field of catalysis as well as for the synthesis of catalytic materials and for the development of microreactors. The first part of this work consisted in transposing on the microfluidic scale the synthesis of Turkevich gold nanoparticles produced classically in standard laboratory glassware. Owing to the fine control on the experimental conditions in the micrometric scale (temperature, flow rates and reactant concentration), it was possible, by the introduction of a simple microfluidic system to obtain particles with an average diameter well below (1.8 nm) with a low size distribution compare to those obtained in conventional glassware synthesis (15 nm). To characterize the formation of this new type of nanoparticles, various characterization methods have been employed, the most common (UV-Vis spectroscopy, TEM), and the most modern such as dynamic light scattering (DLS) or X-ray Absorption Near Edge Structure (XANES) at the SOLEIL synchrotron. In the second part, we introduce the development of a catalytic microreactor functionalized with gold particles starting from silica micrometric capillaries. After characterizing the nature and quantification of the active phase on the inner surface of the capillary, the microreactor is tested on a model reaction: the benzyl alcohol oxidation in liquid phase. Its reactivity, compared to a conventional reactor, allowed highlighting the contribution of this microfluidic technology compared to existing technologies
Réacteurs structurés pour réactions exothermiques : application à l'oxydation déshydrogénante du propane sur catalyseurs VOx/TiO2 déposés sur plaques et mousses en acier inox by Adil Essakhi( Book )

2 editions published in 2012 in French and held by 2 WorldCat member libraries worldwide

The heterogeneous catalyst V2O5/TiO2 is used industrially for the oxidation of o-xylene to phtalic anhydride. It has been the object of numerous works since more than thirty years and constitutes an interesting model solid/solid interface. It has also been studied for the exothermic reaction of oxidative dehydrogenation of propane. However, combustion reaction being favored, the selectivity to propylene decreases as conversion increases and is strongly dependent on temperature. Traditional fixed packed bed reactors do not allow a good dissipation of heat thus generating hot spots producing CO2 and rapid catalyst deactivation. We have tried to better control the heat transfer of this reaction by using a coated structured reactor. Stainless steel was chosen as structuring material due to its common use in industrial reactors and for its heat conductivity. The steps leading to mechanically, thermally and chemically stable coatings of V2O5/TiO2 on metallic substrates have been studied. To avoid poisoning of the active VOx phase by elements migrating from the substrate, a protective amorphous silica layer was deposited by Remote Plasma Enhanced Chemical Vapor Deposition. Coating parameters have first been determined for plane plates representative of reactor walls and then adapted to macroporous foam inserts. At all steps of preparation, the coatings have been characterized by several techniques (XRD, Raman Spectroscopy, Electron Probe Micro Analysis ...). The catalytic properties have then been compared to V2O5/TiO2 powder catalysts in similar operating conditions. Using the structured reactor, yield in propylene could be increased by 50% at 10% conversion
Réactivation des oxydes d'uranium en vue de leur hydrofluoration : influence des additifs et mécanismes by Rudy Thomas( Book )

2 editions published in 2011 in French and held by 2 WorldCat member libraries worldwide

In France, the various steps of the nuclear fuel treatment are said to form a closed cycle. The front end of the cycle consists in the uranium treatments from its extraction out of mines until its use in reactor. In the current process, a series of chemical treatments purify the uranium ore and lead to the formation of uranium fluorides (UF4, UF6). This transformation is a preliminary step before the uranium enrichment by means of using gaseous diffusion or ultracentrifugation. For economical and environmental reasons, the current process is going to be modified. The modifications imply to reactivate the uranium oxides coming from the mines in order to increase their reactivity in hydrofluorination. A process which permits to increase the reactivity of uranium oxide in hydrofluorination was set up. The reaction mechanism and the influence of various parameters of this new process have been identified and the thermal decomposition of the formed products were studied
Immobilisation of metathesis catalysts on mesoporous materials for the conversion of bio sourced fatty compounds by Anna Matzen-Fredel( Book )

2 editions published in 2012 in English and held by 2 WorldCat member libraries worldwide

As fossil resources constantly decrease, the concept of bio-refinery is a most attractive approach to generate chemicals from renewable resources. In this context, unsaturated fatty acids derived from the hydrolysis of crops extracted-triglycerides are a major class of substrates. These must be converted to high added-value derivatives: catalytic transformations can play a key role in this, by converting such compounds into other functionalized derivatives. A most attractive reaction to meet this challenge is olefin metathesis. Based on product/catalyst separation and catalyst recycling issues, use of heterogeneous catalysts is of high interest.We thus prepared heterogenized commercial ruthenium catalysts. The hybrid materials were prepared in a two-step procedure: after silver salt-mediated cationization, the organometallic species were immobilized by ion exchange on mesoporous aluminosilicates of the MCM-41 family. The novel catalysts were characterized by solid-state NMR, IR, XRD, BET, elemental analysis and TGA. They were successfully applied in several metathesis reactions involving the archetypic methyl oleate, a C18 unsaturated ester, with different grades of purity. The probed reactions were self-metathesis, ethenolysis and cross-metathesis with functionalized olefins derived from acrylic and crotonic acids. Though recycling was not completely successful, the supported catalysts were able to efficiently catalyze all these transformations, providing in some instances the first heterogeneously examples of such reactions with high activity and selectivity
« Design » et approche prédictive de nouveaux oxyphosphates de bismuth by Diana Endara( Book )

2 editions published in 2012 in French and held by 2 WorldCat member libraries worldwide

This work consisted in applying an original predictive approach, to predict and develop new inorganic compounds in the ternary system Bi2O3-P2O5-MOx (where M is a cation or a mixture of cations of different types). The systematic rationalization of already existing structures permits to infer from a structural point of view that these phases were the result of the organization of building units (Bus) based on tetrahedrons O(Bi,M)4 connected to form ribbons or columns. This work deals with the diversification of the building units, their size and their arrangement to expand the possibilities of assemblies. Empiric rules have been established for a real and rational prediction of new complex inorganic structures. Non-centro-symmetric materials (NCS) were obtained. The presence of Bi3 + lone pair in these compounds induced strong linear optical properties that have been tested. This work includes the description, validation, development, structure and properties of new bismuth oxo-phoshates
Synthèse de couches minces de Cu(In,Ga)Se2 pour cellules solaires par électrodépôt d'oxydes mixtes de cuivre-indium-gallium by Aurélien Duchatelet( Book )

2 editions published in 2012 in French and held by 2 WorldCat member libraries worldwide

Thin film solar cells based on Cu(In,Ga)Se2 can reach conversion efficiency higher than 20 % by vacuum deposition techniques. In order to decrease the production costs, other techniques are considered. One of them, already developed at the industrial level, consists in the electrodeposition of Cu, In and Ga by stacks on a molybdenum substrate, and then to selenize the layer by reactive thermal treatment. The alternative way developed in this work consists in taking advantage of the strong affinity of indium and gallium for oxygen by electrodeposition of the three elements as oxides, then to reduce the layer by reactive annealing. The electrodeposition mechanism is studied by voltamperometry and chronoamperometry. It is based on a local pH increase at the electrode surface by nitrate reduction that enables copper, indium and gallium oxides/hydroxides precipitation. Electrodeposition conditions are optimized and deposits are characterized. The reduction of the oxide layer by annealing is then studied under hydrogen atmosphere diluted in an inert gas. The reduction kinetic of gallium oxide is very slow and the optimized annealing conditions lead to the formation of GaMo3 phase in addition to the expected Cu-In-Ga alloys. The selenization at 550°C leads to the formation of CuInSe2 and the segregation of Ga near the cell back contact. First cell results obtained by this process show conversion efficiency up to 9.4%. A multi-step selenization process is developed and enables a better Ga homogeneity in the layer
 
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Audience Level
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  General Special  
Audience level: 0.93 (from 0.92 for Indirect a ... to 0.94 for Synthèse ...)

Alternative Names
École nationale supérieure de chimie de Lille. Unité de catalyse et chimie du solide (UCCS) (Villeneuve d'Ascq (Nord))

UCCS - Unité de catalyse et de chimie du solide de Lille

Université d'Artois. Unité de catalyse et chimie du solide (UCCS)

Université Lille 1 - Sciences et technologies. Unité de catalyse et chimie du solide (UCCS) (Villeneuve d'Ascq(Nord))

Languages
French (26)

English (14)