Auswahl der wissenschaftlichen Literatur zum Thema „Catalyseurs au molybdène – Synthèse (chimie)“
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Zeitschriftenartikel zum Thema "Catalyseurs au molybdène – Synthèse (chimie)":
Mazars, François. „Caffeine, a natural renewable resource for the synthesis of biobased catalysts“. Bulletin de la Société Royale des Sciences de Liège, 2023, 153–70. http://dx.doi.org/10.25518/0037-9565.11461.
Dissertationen zum Thema "Catalyseurs au molybdène – Synthèse (chimie)":
Porcher, Jean-Philippe. „Synthèse de complexes bioinspirés de Mo et W catalyseurs pour la réduction des protons“. Thesis, Paris 6, 2015. http://www.theses.fr/2015PA066301/document.
Enzymes containing molybdenum or tungsten within their active sites appear to be present in all form of life. Most of them are oxotransferase or hydroxylase. They contain one or two pyranopterin-dithiolene cofactor, also called Moco, in which the metal is coordinated by the dithiolene moiety. The molybdenum cofactor is highly unstable and mimicking the active site of these enzymes is challenging. A new strategy for the synthesis of a pyranopyrazine dithiolene ligand (qpdt) has been developed in our laboratory. The corresponding molybdenum complex (Bu4N)2[MoO(qpdt)2] was synthesized and characterized extensively. This unique Mo-enzyme biomimetic complex demonstrated its potential for H2 production. This complex was shown to be active for the photoreduction of protons in acidic conditions (pH = 4), in the presence of the catalyst, the photosensitizer Ru(bpy)32+, ascorbic acid in exces and gave excellent activities of 500 TON with a high stability in aqueous organic media. Moreover, the electroreduction of protons by this complex in acetonitrile showed a remarkable rate constant value of 1030 s-1 at 1.3 V. (vs Ag/AgCl). To valorize this very original ligand qpdt, (Et4N)[Ni(qpdt)2] and (Et4N)2[Co(qpdt)2]2 bisdithiolene complexes were synthesized and characterized. Preliminary studies of theses complexes have shown a potential for the photoreduction and the electroreduction of protons. These results open new directions for the search of proton reduction catalysts. This first biomimetic complex should also be exploited to understand the chemistry of this class of oxidoreductase that is still not well understood
Ghazi, Mohamed. „Conversion du gaz de synthèse en produits oxygénés en présence de catalyseurs nickel-molybdène supportés“. Poitiers, 1988. http://www.theses.fr/1988POIT2006.
Hoffmann, Pascal. „Synthèse de nouvelles métalloporphyrines halogénées : accès à de nouveaux catalyseurs biomimétiques d'oxydation“. Toulouse 3, 1991. http://www.theses.fr/1991TOU30207.
Thavornprasert, Kaew-arpha. „Production of acetals from bio-resourced alcohols over bifunctional catalysts“. Electronic Thesis or Diss., Lille 1, 2013. http://www.theses.fr/2013LIL10016.
The severe environmental issues caused by the fossil-based sources consumption have driven numerous studies to find alternative sustainable resources. Biomass is a renewable feedstock for a large spectrum of valuable chemicals especially for fuels applications. Acetals, dimethoxymethane (DMM) and diethoxythane (DEE), can be produced from biomass-derived methanol and ethanol, respectively. Herein, a concept of synthesizing acetals via a one-step alcohol conversion is applied instead of the currently used two-steps reactions of alcohol partial oxidation/acetalization. The DMM synthesis is studied on FeMo mixed oxide having needed redox/acidic functions. 50 % of DMM yield is achieved at 255 °C on the catalyst with a Mo/Fe ratio of 3.2. DMM selectivity is boosted when using a methanol-rich (40 mol.%) feed and a high selectivity is kept up to 60 % of methanol conversion. A synergistic effect between Mo and Fe species on the conversion is evident. The active sites incorporating Mo and Fe cations is suggested, involving lattice O2- and anionic vacancies generated by surface dehydroxylation. LEIS analysis confirms the presence of Mo and Fe species in the outermost atomic layer. XPS and in situ EPR studies show that Fe centers provide the redox property. The acidity is brought by anionic vacancies acting as Lewis acid. XPS results confirm the role of gas-phase O2 to reoxidize the surface and regenerate the active sites. FeMo-based catalysts were applied in the DEE synthesis due to analogous pathways of methanol/ethanol reactions. The catalyst is not selectively to acetal DEE as expected, probably due to the steric hindrance or to the inadequate acidic strength of the FeMo system
Bouchmella, Karim. „Synthèse par procédé sol-gel non-hydrolytique de catalyseurs oxydes mixtes pour la métathèse d'oléfines“. Thesis, Montpellier 2, 2013. http://www.theses.fr/2013MON20088.
The non-hydrolytic sol-gel synthesis (NHSG) of Re-Si-Al and Mo-Si-Al mixed oxides was proposed as an innovative one step route to heterogeneous olefin metathesis catalysts. Supported molybdenum oxide catalysts are receiving much attention as a result of their relatively low price, robustness and good activity at low temperature. Supported rhenium oxide catalysts are known to be highly active and selective even at room temperature. However, they are expensive and moderately stable because of the sublimation of the rhenium oxide. The NHSG synthesis used in this work is based on the one pot reaction of chloride precursors (ReCl5 or MoCl3, SiCl4, AlCl3) with diisopropylether (iPr2O) at 110 °C in dichloromethane. The simplicity of NHSG makes it attractive: multi-step procedures, expensive precursors, or reactivity modifiers are not needed. The mixed oxide catalysts exhibited well-controlled compositions and mesoporous textures, with high acid site densities. XRD, XPS and ToF-SIMS showed that the catalysts could be described as an amorphous silica-alumina matrix with well-dispersed Re or Mo surface species. In the case of Re-based catalysts, rhenium losses by sublimation during calcination were observed for the silica-rich formulations. The loss of rhenium could however be avoided by increasing the Al content. More importantly we demonstrate that Re sublimation during calcination of silica-rich formulations is suppressed when the whole preparation procedure (synthesis, washing, drying and calcination) is carried out in the absence of water. Particular attention was devoted to the study of the influence of the composition on texture, structure, acidity and surface properties, which were correlated with the catalytic performances. The performance of selected Re-Si-Al and Mo-Si-Al catalysts was evaluated in the metathesis of propene and in the cross-metathesis of ethene and trans-2-butene. The NHSG catalysts were compared to catalysts of similar compositions prepared by other more methods (impregnation, thermal spreading, flame spray pyrolysis). The catalysts prepared by NHSG have a high specific activity in the metathesis reaction
Oliveira, De Souza Danilo. „Quick-EXAFS and hydrotreating catalysts : chemometrics contribution“. Thesis, Lille 1, 2015. http://www.theses.fr/2015LIL10061/document.
Hydrodesulfurization (HDS) is catalytic process used to remove sulfur from petroleum feedstock. The world claim for clean fuel boosted scientists to get new insights on the catalytic reaction in order to understand the mechanisms of the process and, thus, produce catalysts that are more efficient. Such researches are based mainly in to lines: by one hand, in the formulation of new routes that lead to tailored catalysts and, by the other hand, in a better understanding of the catalytic process at the molecular and atomic level. Particularly, the later leads to an optimization of the formulation and better catalytic performance, for which is required further understanding of the molecular structure, its transformations during the reaction, the nature of active species and its genesis. In this picture, the goal of this work is twofold. First, to present a new route for produce HDS CoMo-based catalysts via one-pot sol-gel method, which revealed to have suitable macro- and microscopic properties making promising solids for further applications. Second, to adapt and use chemometrics method to treat in situ measurements, particularly, X-ray absorption spectra (XAS), to get new insights on the genesis of the catalytic active phase at the molecular level. XAS techniques is suitable to probe local atomic structure, and last generation synchrotron facilities provide conditions to perform such in situ experiments with very fast acquisition (Quick-EXAFS). Chemometrics provide a brand new scope on data analysis and interpretation for extract information on the kinetics of reaction and structure transformation that leads to the active phase of the catalysts
Herbin, Morgane. „Etude de l’influence de différents modes de synthèse sur la nature de la phase active de catalyseurs à base de molybdène : Caractérisation par couplage de spectroscopies XPS/LEIS/ToF-SIMS“. Electronic Thesis or Diss., Lille 1, 2014. http://www.theses.fr/2014LIL10069.
The coupling of surface analysis techniques (XPS, LEIS et ToF-SIMS) allowed to characterize the nature of the active phase on Mo-based catalysts according to different modes of synthesis. To imitate chemical means by impregnation mode, model catalysts we prepared by spin-coating. In addition, a new physical path, by magnetron sputtering, has been explored for the synthesis of catalysts. Correlations between spectroscopic data XPS and LEIS on model systems determine the recovery rate and the structure of the active phase : Mo low content monomeric and high content polymeric entities. Finally, the catalytic performances of the different catalytic systems for the controlled oxidation of methanol are discussed under spectroscopic characterizations. This work has been performed within INTERREG IV CATARR network (Materia Nova, Mons University and Lille1 University)
Fogeron, Thibault. „Synthèse de complexes inspirés des formiate déshydrogénases à Mo/W : application à la catalyse moléculaire de la réduction du CO2“. Thesis, Sorbonne université, 2018. http://www.theses.fr/2018SORUS132.
In the context of global warming, the development of new sources of energy, clean and sustainable, is a key challenge of our society. The reduction of CO2 could allow the storage of renewable energies and offer an answer to the dramatic increase of CO2 in the atmosphere. Development of molecular catalysts offers the possibility of studying the structure-reactivity relationships. However, the library of existing homogeneous catalysts in the literature is quite limited. In order to find new potential catalysts, we decided to take inspiration from the active site of formate dehydrogenases (FDH). The synthesis of molecules mimicking this active site is an interesting challenge. In this thesis, we described the synthesis of two ligands inspired from the molybdopterin (chapter I). The synthesis of CoCp(dithiolène) complexes allows us to better characterize these ligands (chapter II). Moreover, the observation of the reactivity of these ligands allows us to understand their behaviour during electrocatalysis. The [MoO(dithiolene)2]2- complexes obtained from the bio-inspired ligands are,so far, the best mimics of the active site of FDH in the literature (chapter III). In this chapter, the generalization of synthetic procedure was also explored. Finally, [Ni(dithiolene)2]- synthesize from the bio-inspired ligands are the first dithiolene complexes able to reduce CO2 (chapter IV). They are among the few non-nobles metal complexes catalyzing the reduction of CO2 into formate
Dias, Probst Luiz Fernando. „Etude de la conversion des oxydes de carbone en hydrocarbures et en alcools en présence de catalyseurs au Nickel et Molybdène supportés“. Poitiers, 1989. http://www.theses.fr/1989POIT2297.
Pang, Liuqing. „Multi-metal nano-materials as efficient electrocatalysts“. Thesis, Lille 1, 2020. http://www.theses.fr/2020LIL1I013.
Hydrogen (H2) has been considered as the most promising and renewable energy carrier. With the advantages of low cost and high efficiency, electrochemical water splitting is a promising approach to produce H2 with high purity. However, the practical application of water splitting for mass production of H2 is greatly hindered by a higher applied bias voltage and a lower electrode stability required in an electrolyzer arising from two half reactions in water splitting, namely, cathodic hydrogen evolution reaction (HER) and anodic oxygen evolution reaction (OER). Currently, Pt-group metals are the most effective catalysts for HER while the benchmark catalysts for OER are Ir/Ru-based compounds. However, high cost and scarcity of these metals limit their widespread use. Therefore, enormous efforts have been dedicated to the development of nano-scale non-noble metal catalysts with high dispersibility, large specific surface area, and electrocatalytic activity for water splitting. In this thesis, we have explored high-efficiency, high-stability, low-price electrocatalysts using a simple and environmentally friendly process. Firstly, we prepared new PtRu2 nanoparticles supported on sulphur- and nitrogen-co-doped crumbled graphene with trace amounts of iron (PtRu2/PF) electrocatalyst by one-step hydrothermal process. The PtRu2/PF catalyst achieved a current density of 10 mA·cm-2 at a low overpotential value of only 101 mV for HER at pH=1 and a current density of 10 mA cm-2 at an overpotential of only 238 mV for the OER in alkaline solution. Interestingly, this catalyst was also efficient for methanol oxidation reaction (MOR) in acidic solution and oxygen reduction reaction (ORR) in 0.1 M KOH solution. Secondly, we described the preparation of a hybrid material consisting of cobalt oxide decorated on nitrogen-doped MoS2 supported on carbon fibers (CoO/N-MoS2/CF) through a two-step process combining hydrothermal technique and electrochemical deposition. The CoO/N-MoS2/CF achieved a current density of 10 mA cm-2 at an overpotential of only 78 mV for the HER and a current density of 50 mA cm-2 at 458 mV for the OER in 1.0 M KOH. Additionally, the CoO/N-MoS2/CF delivered a maximum current density of 53 mA cm-2 at an applied cell voltage of 1.5 V for a two-electrode water splitting. Thirdly, we showed for the first time the extraordinarily capacity of perforated gold nanoholes (Au NHs) electrodes for electrochemical water splitting under illumination with light. The strong plasmonic electromagnetic enhancement, which occurs under illumination of the perforated Au NHs electrode, facilities the dissociation of water into H2. The overpotential for the HER occurs on such plasmonic electrodes at a current density of 100 mA cm-2 was 205 mV, largely improved compared to the reference material, Pt. The fast electrocatalytic behavior of the interface was attested by a low Tafel slope of 33 mV dec-1. All of these materials were characterized by a variety of different techniques, such as SEM, TEM, XRD, XPS, Raman and electrochemical measurements
Bücher zum Thema "Catalyseurs au molybdène – Synthèse (chimie)":
LIEBSKIND. Advances in Metal-Organic Chemistry, Volume 3 (Advances in Metal-Organic Chemistry). JAI Press, 1994.
Auge, J., B. Betzemeier, D. P. Curran, Paul Knochel und B. Cornils. Modern Solvents in Organic Synthesis. Springer London, Limited, 2003.
(Contributor), J. Auge, B. Betzemeier (Contributor), B. Cornils (Contributor), D. P. Curran (Contributor), P. Knochel (Contributor), W. Leitner (Contributor), B. Linclau (Contributor) et al., Hrsg. Modern Solvents in Organic Synthesis (Topics in Current Chemistry). Springer, 1999.
Knochel, Paul. Modern Solvents in Organic Synthesis. Springer, 2013.