Дисертації з теми "Catalyseurs au molybdène – Synthèse (chimie)"
Оформте джерело за APA, MLA, Chicago, Harvard та іншими стилями
Ознайомтеся з топ-50 дисертацій для дослідження на тему "Catalyseurs au molybdène – Synthèse (chimie)".
Біля кожної праці в переліку літератури доступна кнопка «Додати до бібліографії». Скористайтеся нею – і ми автоматично оформимо бібліографічне посилання на обрану працю в потрібному вам стилі цитування: APA, MLA, «Гарвард», «Чикаго», «Ванкувер» тощо.
Також ви можете завантажити повний текст наукової публікації у форматі «.pdf» та прочитати онлайн анотацію до роботи, якщо відповідні параметри наявні в метаданих.
Переглядайте дисертації для різних дисциплін та оформлюйте правильно вашу бібліографію.
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
Sarrazin, Patrick. "Chimie de l'interaction de molybdates avec l'alumine Yc pure et modifiée par le silicium." Lille 1, 1989. http://www.theses.fr/1989LIL10152.
Albano, E. Mpinzi Kanga. "Transformation du gaz de synthèse en méthanol sur des catalyseurs à base de platine promu au molybdène." Lyon 1, 1987. http://www.theses.fr/1987LYO10103.
Caron, Laurent. "Microémulsions oxydantes polyphasiques : synthèse et utilisation de catalyseurs amphiphiles optimaux." Lille 1, 2005. https://pepite-depot.univ-lille.fr/RESTREINT/Th_Num/2005/50376_2005_386.pdf.
Urresta, Aragon Julian Diel. "Conversion sélective de gaz carbonique en alcools et en hydrocarbures en présence de catalyseurs à base de molybdène." Poitiers, 1995. http://www.theses.fr/1995POIT2352.
Bakala, Pipi Massala Paul Célestin. "Synthèse et caractérisation de catalyseurs mésoporeux insérant du molybdène (VI) ou du rhénium (V/VII) : application à l'époxydation ou à la métathèse des oléfines, comparativement aux catalyseurs industriels." Paris 6, 2007. http://www.theses.fr/2007PA066005.
Sampieri-Croda, Alvaro. "Synthèse de catalyseurs à base de sulfures de molybdène et nickel-molybdène supportés sur oxydes mésoporeux MCM-41 et SBA-15 : Application en hydrodésulfuration." Paris 6, 2005. http://www.theses.fr/2005PA066071.
Chatron-Michaud, Pascal. "Synthèse de banques de catalyseurs pour la polymérisation d’oléfines." Rennes 1, 2009. http://www.theses.fr/2009REN1S196.
The first chapter deals with the design of a new ligands library for the ethylene polymerization. A high throughput synthesis and screening approach is developed during this chapter to test a library of 2-iminobenzimidazole complexed on various late transition metals. This makes possible to draw conclusion on this type of ligands as well as for general polymerization important factors (temperature, pressure…) The second and the third chapters deal with the modification of bis-imine ligands by introducing a pyridyle group. This pyridyle group makes the ligands potentially N-alkylable, which changes the ligands and catalysts behaviours. The influence of the N-alkylation on those catalysts has been studied through NMR, FTIR and polymerization experiments. The last chapter is to make a method for the synthesis and the heterogeneous screening of unbridged métallocènes. The method has been applied on 36 catalysts
Brunet, Lionel. "Synthèse et chimie de coordination de ligands phosphorés peu ou pas oxydables." Palaiseau, Ecole polytechnique, 1994. http://www.theses.fr/1994EPXX0007.
Dji, Gabriel. "Etude de composés mixtes nickel-molybdène et de quelques propriétés des catalyseurs issus de leur réduction." Lyon 1, 1985. http://www.theses.fr/1985LYO10030.
Guevara, Lara Alfredo. "Effets de support et de solvant dans l'évaluation de l'activité des catalyseurs d'hydrotraitement nickel-molybdène supportés sur oxydes mixtes." Lyon 1, 2003. http://www.theses.fr/2003LYO10017.
Thomas, Amélie. "La synthèse de nouveaux catalyseurs organométalliques à base d'hétéropolyacides supportés sur silice." Lyon 1, 2007. http://www.theses.fr/2007LYO10340.
Salembier, Hélori. "Développement de catalyseurs supportés pour la synthèse directe du méthylmercaptan à partir de CO/H2/H2S et CO2/H2/H2S." Thesis, Lille 1, 2017. http://www.theses.fr/2017LIL10207.
In the field of chemistry, industrial research is committed to the development of environmentally friendly synthesis strategies. Methyl mercaptan (CH3SH) is a precursor to methionine whose worldwide demand is steadily growing. It is currently produced by a catalytic reaction between H2S and methanol. Due to the production of methanol involving multiple reaction steps, the direct synthesis of methyl mercaptan from syngas (CO/H2) and H2S or from (CO2/H2) and H2S (assuming a CO2 recycling) appears as a financially attractive industrial process. This work focused on the development of new catalysts for this reaction, specifically on identifying and quantifying the active phase of different catalytic systems. Studies on the effects of molybdenum loading, calcination procedures and copper and/or zinc doping were carried out on an alumina-supported potassium-molybdenum catalyst. Others metal oxide carriers were also employed, remarkably improving catalytic performances. Catalytic tests were performed with a micro-pilot reactor operated in near-industrial conditions. Catalysts were characterized using X-ray photoelectron spectroscopy, transmission emission microscopy, X-ray diffraction and Raman spectroscopy, evidencing the presence of a significant lamellar 1T-MoS2 type phase, intercalated by potassium ions. Quantification of this intercalated phase was correlated with methyl mercaptan productivity, demonstrating its role as the catalytically active phase which drives methyl mercaptan direct synthesis
Riollet, Virginie. "Vers la synthèse d'une nouvelle classe de catalyseurs d'époxydation pour la chimie fine." Lyon 1, 2002. http://www.theses.fr/2002LYO10140.
Taban, Caliskan Gülnur. "Synthèse et caractérisation de polyoxométallates organométalliques de molybdène et de tungstène en milieu aqueux." Toulouse 3, 2012. http://thesesups.ups-tlse.fr/1908/.
In this thesis, the reaction of [Cp*2M2O5] complexes with Na2M'O4 (M, M' = Mo, W) in different stoichiometric ratios has been investigated in an acidic aqueous medium. It is a mild and selective entry into well-defined Lindqvist-type organometallic mixed-metal Polyoxometalates. Using a 1:4 ratio leads to the neutral compounds [Cp*2MoxW6-xO17] (for x = 6, 4, 2, 0), of which the two mixed-metal systems [Cp*2Mo2W4O17] and [Cp*2Mo4W2O17] were not previously reported. The identity of the complexes is demonstrated by elemental analysis, thermogravimetric analysis and infrared spectroscopy. The molecular identity and geometry of compound [Cp*2Mo4W2O17] is further confirmed by a fit of the powder X-ray diffraction pattern with a model obtained from previously reported single-crystal X-Ray structures of [Cp*2Mo6O17] and [Cp*2W6O17], with which [Cp*2Mo4W2O17] is isomorphous. The formula of these compounds may also be written as [(Cp*M)2(M'O)4(µ2-O)12(µ6-O)]. The relative position of the M and M' atoms is perfectly defined by the nature of the starting materials, the M element from the organometallic reagent ending up selectively in the (Cp*M) positions and the M' element from the inorganic reagent occupying selectively the (M'O) positions. Thermal decomposition of these compounds yields the mixed-metal oxides Mo2/3W1/3O3 and Mo1/3W2/3O3 with an expected homogeneous distribution of the two metals. When the same synthetic procedure is carried out with [Cp*2M2O5] and Na2M'O4 (M, M' = Mo, W) in a 1:10 ratio, the anionic organometallic mixed-metal polyoxometalates [Cp*MM'5O18]- (M, M' = Mo, W) are obtained. This family was previously represented only by the homometallic Mo member, obtained by two different and less efficient synthetic strategies. All these compounds have been isolated as salts of nBu4N+, nBu4P+ and Ph4P+ cations. The compounds have been characterized by elemental analysis, thermogravimetric analysis, electrospray mass spectrometry, and infrared spectroscopy. The molecular identity and geometry of compounds Ph4P[Cp*Mo6O18] and Ph4P[Cp*WMo5O18] have been confirmed by single crystal X-ray diffraction. The compounds show characteristic M=O and M-O-M vibrations in the IR spectrum. As found for all POM derivatives, the terminal M'=Ot and M''=Ot vibrations (950-1000 cm-1) have higher frequency, than the M-Ob-M vibrations (750-890 cm-1). The 1H NMR spectra of the isolated products for the new anionic POM's show the Cp* signal at d 2. 2 (when linked to Mo) or 2. 4 (when linked to W), plus the resonances of the cation with suitable intensity for the 1:1 Cp*/cation stoichiometry. The 31P NMR spectrum of the phosphonium salts shows the expected cation resonance at d 23. 4 for Ph4P+ and d 35. 1 for Bu4P+. All anionic compounds were also investigated in terms of their thermal behavior by thermogravimetric analysis (TGA) in air. The salts with N-based cation (Bu4N+) lead to complete loss of the organic part, with formation of the mixed-metal trioxides Mx/6M'1-x/6O3 (x = 0, 1, 5, 6), with a relatively good match between experimentally observed and theoretical mass losses upon warming up to 500 °C. TGA of the salts with phosphonium cations (Bu4P+ and Ph4P+) gave indication of phosphorus loss or not depending on the anion, without a clear rationalization. All anions were also investigated by mass spectrometry using an electrospray injection method. The spectrum in negative mode showed the expected molecular ion with an isotopic pattern in good agreement with the simulation. The fragmentation pattern is not identical for each type of anion, but as a general feature, we can observe a loss of the Cp* fragment to yield [MM'5O18]-, followed by the subsequent loss of both MO3 and M'O3
Le, Brazidec Jean-Yves. "Synthèse de bêta-C-glucosides catalysée par le palladium(0) et application à la synthèse de dérivés oxacycliques." Aix-Marseille 3, 1995. http://www.theses.fr/1995AIX30063.
Brunel, Jean-Michel. "Catalyseurs organophosphorés chiraux : synthèse et application dans les réactions de réduction énantiosélective par le borane." Aix-Marseille 3, 1994. http://www.theses.fr/1994AIX30043.
Moutou, Joseph-Marie. "Synthèse et caractérisation de quelques oxyfluorures de tungstène et de molybdène d'alcalins et de cuivre." Bordeaux 1, 1985. http://www.theses.fr/1985BOR10577.
Blanc, Alexandre. "Bases organiques fortes ancrées sur silices mésoporeuses. Applications en chimie organique fine." Montpellier 2, 2002. http://www.theses.fr/2002MON20188.
Sanz, Martial. "Ligands cyclopentadienyles et indenyles chiraux : application en chimie organométallique et en catalyse homogène." Aix-Marseille 3, 1998. http://www.theses.fr/1998AIX30075.
Senninger, Thierry. "Role de composés oxygénés en polymérisation de l'éthylène par des complexes du zirconium." Lyon 1, 1996. http://www.theses.fr/1996LYO10034.
Audic, Nicolas. "Immobilisation de catalyseurs organométalliques sur supports solubles. Applications en synthèse organique." Rennes 1, 2003. http://www.theses.fr/2003REN10082.
Duribreux, Isabelle. "Synthèse et étude structurale de nouveaux molybdates et vanadates d'uranyle et de cations monovalents." Lille 1, 1997. http://www.theses.fr/1997LIL10065.
Guerrero, Fajardo Carlos Alberto. "Oxidación selectiva de metano hasta formaldehído." Université Louis Pasteur (Strasbourg) (1971-2008), 2008. https://publication-theses.unistra.fr/public/theses_doctorat/2008/GUERRERO_FAJARDO_Carlos_Alberto_2008.pdf.
The formaldehyde synthesis has three stages: the methane is reformed into synthesis gas (CO/H2) then the syngas is converted into methanol which is then partially oxidized until formaldehyde. The methane direct catalytic oxidation into formaldehyde would avoid the methane reforming stage, very expensive in energy, approximately 60% of the current process total cost. The catalysts for the methane conversion to formaldehyde can be vanadium, tungsten and molybdenum oxides, supported on silica, alumina or zirconia. The selectivities are low when the conversions exceed 10%. This work was centered on the use of molybdenum and iron oxides catalysts supported on silica and titania. The catalytic tests were carried out to atmospheric pressure, temperature 400-800°C, flow ratio: CH4/O2/N2/He= 7,5/1/4/14 with a 65,5 mL. Mn-1 as total flow. The products are analyzed by gas chromatography. The optimal time volumetric speed was 60. 000 h-1. The metals integration in the silica matrix displays a positive effect on the formaldehyde selectivity. The molybdenum addition is synergistic with the formaldehyde production. The best catalyst for the formaldehyde production is the 0,5%wt Fe, beyond this content the formaldehyde selectivity decrease. The formaldehyde yield obtained is 0,45% (150,0 gHCHO. Kg-1cata h-1). For this same content of iron, the molybdenum addition with the content of 0,5% wt makes it possible to increase the yield until 0,54% (218,0 gHCHO. Kg-1cata. H-1)
Liu, Chang. "Effect of sulphur on Fischer-Tropsch synthesis : promoted molybdenum and cobalt catalysts." Thesis, Lille 1, 2015. http://www.theses.fr/2015LIL10134/document.
This thesis focuses on the study of promoted molybdenum catalysts supported on alumina or carbon nanotubes for the synthesis of olefins from synthesis gas obtained from biomass. The catalysts were studied at every stage of their preparation by different characterization techniques and tested in fixed bed reactor. The results showed that both types of sites are present on the K-MoS2 catalysts: MoS2, which leads to the production of methane and a mixed K-Mo-S phase which leads to the synthesis of olefins. The decrease in activity observed with catalysts supported on carbon nanotubes was attributed to the low rate of sulphidation. The basicity of the promoters and the size of the molybdenum sulphide crystallites are important parameters influencing the olefins synthesis. A moderate basicity as well as large size of molybdenum crystallites are favorable to the synthesis of light olefins
Martin, Sandrine. "Synthèse de ligands cyclopentadienyles et indenyles dérivés des sucres : applications en chimie organométallique." Aix-Marseille 3, 1999. http://www.theses.fr/1999AIX30025.
Pandarus, Valerica. "Une nouvelle classe de catalyseurs hétérogènes au palladium et au platine pour la chimie organique de synthèse." Doctoral thesis, Université Laval, 2019. http://hdl.handle.net/20.500.11794/36595.
Tout d’abord, le support organosilicique a été dopé avec des unités Al₂O₃. Les nouveaux catalyseurs à base de NPs de Pd/Pt sur un support organosilicique dopé avec des unités Al₂O₃, Pd⁰/MeSiO₁, ₅- Al₂O₃ et Pt⁰/MeSiO₁, ₅- Al₂O₃, se sont démarqués par une stabilité élevée à l'air et à l'humidité. L’ajout de 2 % massique d’Al₂O₃ a permis d’augmenter la teneur en Pd de 0,5 à 2,0 % massique et la teneur en Pt de 2,0 à 5,0 % massique tout en maintenant une très grande dispersion du métal (NPs de Pd/Pt d’environ 2-4 nm). L’ajout d’Al₂O₃ a également augmenté leur activité catalytique autant dans des conditions douces qu’à température et pression élevées, en raison de la présence des sites acides. Cependant, les deux catalyseurs de morphologie irrégulière, synthétisés par une méthode sol-gel in-situ, ont échoué dans les essais de réutilisation. Cela est expliqué par la faible résistance mécanique du support en favorisant le frittage des NPs métalliques Afin d’augmenter la résistance mécanique du support et d’améliorer l’activité catalytique des catalyseurs hétérogènes au Pd/Pt, le procédé de synthèse sol-gel in-situ générant des matériaux de morphologie incontrôlable a été remplacé par un procédé de précipitation dans lequel des NPs métalliques ont été séquestrées dans les cages mésoporeuses d’une matrice 100 % organosilicique de morphologie sphérique. La synthèse des particules sphériques a été réalisée par un procédé d’émulsion huile-dans-eau en utilisant seulement du MTES comme précurseur de silice. Ce type de synthèse a permis de faire une condensation à une température de 90 °C pendant 24 h, ce qui a fortement augmenté la robustesse du support. L’activité catalytique du catalyseur de morphologie sphérique Pd⁰/MeSiO₁, ₅ avec une teneur en Pd de 2,5 % massique (NPs de Pd de 2-3 nm), a été évaluée dans l’hydrogénation catalytique du squalène végétal en l’absence de solvant, dans des conditions douces mais également dans des conditions plus sévères de température et de pression. Le catalyseur s’est avéré actif à des températures supérieures à 70 °C et à des pressions d’H₂ de 3 à 20 atm, pour des pourcentages molaires de Pd par rapport au squalène de 0,50 à 0,05 mol %. Le catalyseur a été facilement récupéré et réutilisé dans huit réactions consécutives avec de très petites quantités de Pd lessivé dans le produit brut de réaction (inférieure à 1 mg kg⁻¹), ouvrant ainsi la voie à une hydrogénation écologique et moins coûteuse du squalène végétale. L’activité catalytique du catalyseur de morphologie sphérique Pt⁰/MeSiO₁, ₅ avec une teneur en Pt de 5 % massique (NPs de Pt de 4-7 nm) a été évaluée dans l’hydrosilylation des oléfines en l’absence de solvant et à l’air.
Le catalyseur s’est avéré actif pour des pourcentages molaires de Pt par rapport à l’oléfine de 0,100 à 0,005 mol %. Le catalyseur a été facilement récupéré et réutilisé dans trois réactions consécutives avec de très faibles quantités de Pt lessivé dans le produit brut de réaction (inférieures à 5 mg kg⁻¹). Ce type de synthèse a permis de développer des catalyseurs plus actifs (conversion et sélectivité supérieures à 90 %), stables et réutilisables, ouvrant la voie à des applications vertes et moins coûteuses, d’une importance primordiale pour la chimie fine et pour l’industrie pharmaceutique. Ce projet se démarque par son originalité dans le type unique des supports développés pour séquestrer les NPs de Pd/Pt. Le caractère hydrophobe des supports synthétisés exclusivement à partir du silane hybride protège les NPs métalliques de l'oxydation. Nous avons montré que le xérogel de silice modifiée organiquement (100 % MTES) de morphologie sphérique et fonctionnalisée avec des NPs de Pd ou de Pt, Pd⁰/MeSiO₁, ₅ et Pt⁰/MeSiO₁, ₅ , conduit à des catalyseurs robustes, stables à l’air et à l’humidité, hautement actifs et sélectifs. Des essais catalytiques réalisés sur une période de deux ans avec les deux catalyseurs, conservés dans des conditions innertes ou à l’air, à 4 °C et à 22 °C, ont montré une activité catalytique inchangée. Les analyses d’adsorption d’N₂ et les analyses de difusion de la lumière ont montré des caractéristiques physiques similaires, même après deux ans. Comparés à d’autres catalyseurs commerciaux utilisés dans l’industrie, les catalyseurs hydrophobes de morphologie sphérique Pd⁰/MeSiO₁, ₅ et Pt⁰/MeSiO₁, ₅, commercialisés par SiliCycle Inc comme SiliaCat Pd⁰ et SiliaCat Pt⁰, ont montré les meilleures performances catalytiques. Ils peuvent facilement être manipulés à l'air, ne montrant aucune tendance à s'enflammer. Les catalyseurs développés sont disponibles pour effectuer des réactions en présence ou en l’absence de solvant, dans des conditions douces, mais également à des températures et à des pressions élevées. Ceci permert d’offrir des méthodes économiques appropriées pour fabriquer des produits à moindre coût, en utilisant des procédés totalement écologiques.
The addition to 2 wt% of Al₂O₃ made it possible to increase the Pd content from 0.5 to 2.0 wt% and the Pt content from 2.0 to 5.0 wt% while keeping a very high metal dispersion (Pd/Pt NPs of size 2-4 nm). The addition of Al₂O₃ also made it possible to increase their catalytic activity under mild conditions as well as at high temperature and pressure, due to the presence of acidic sites. However, both catalysts, synthesized by an in-situ sol-gel method, failed in the reuse tests. This is explained by the low mechanical resistance of the support favoring the sintering of metal NPs. To increase the mechanical resistance of the support and to improve the catalytic activity of Pd/Pt heterogeneous catalysts, the in-situ sol-gel synthesis process was replaced by a precipitation process where the metal NPs were sequestered in the mesoporous cages of a 100% hydrophobic organosilica support of spherical morphology. The synthesis of the spherical particles was carried out by an oil-in-water emulsion process using only MTES as a source of silica. This type of synthesis allowed extensive condensation at 90 °C for 24 h, which greatly increased the robustness of the support. The catalytic activity of the Pd⁰/MeSiO₁, ₅ spherical morphology catalyst, with a Pd content of 2.5 wt% (Pd NPs of size 2-3 nm) was evaluated in the catalytic hydrogenation of vegetable squalene in the absence of solvent, in mild conditions but also under more severe conditions of temperature and pressure. The catalyst was found to be active at temperatures above 70 °C and at H₂ pressures of 3 to 20 atm, for molar percentage of Pd relative to squalene of 0.50 to 0.05 mol %. The catalyst was easily recovered and reused in eight consecutive reactions with very small amounts of leached Pd in the reaction crude product (less than 1 mg kg⁻¹) paving the way for environmentally friendly and less expensive vegetable squalene hydrogenation. The catalytic activity of the Pt⁰/MeSiO₁, ₅ spherical morphology catalyst with a Pt content of 5 wt% (Pt NPs of size 4-7 nm) was evaluated in the hydrosilylation of olefins in the absence of solvent and in the air. The catalyst was found to be active at molar percentage of Pt relative to the olefin of 0.100 to 0.005 mol%. The catalyst was easily recovered and reused in three consecutive reactions with very small amounts of leached Pt in the silylated reaction crude product (less than 5 mg kg⁻¹). This type of synthesis has made it possible to develop catalysts that are more active (conversion and selectivity greater than 90%), stable and reusable, paving the way for green and less expensive applications, of paramount importance for fine chemistry and for pharmaceutical industry.
The originality of this project consists of the unique type of supports developed to encapsulate Pd/Pt NPs. The hydrophobicity of the supports synthesized exclusively from the organosilanes protects the metal NPs against oxidation. We have shown that the organically modified (100% MTES) spherical silica xerogel functionalized with NPs of Pd or Pt, Pd⁰/MeSiO₁, ₅ and Pt⁰/MeSiO₁, ₅, leads to highly active and selective, stables to air and moisture, robust catalysts. The catalytic test, carried out during a periode of two years with the two Pd/Pt catalysts stored under inert conditions or in air at 4 °C and 22 °C, showed unchanged catalytic activity. N₂- adsorption and light scattering analyzes showed similar physical characteristics even after two years. Compared with other commercial catalysts used in industry, the spherical hydrophobic catalysts Pd⁰/MeSiO₁, ₅ and Pt⁰/MeSiO₁, ₅, marketed by Silicycle Inc. as SiliaCat Pd⁰ and SiliaCat Pt⁰, showed the best catalytic performance. They can be easily handled in the air showing no tendency to ignite. The catalysts developed are available for carrying out reactions in the presence or absence of solvent, under mild conditions, but also at high temperature and pressure, thus offering economical methods suitable for making low-cost products, using a completely ecological process.
The heterogeneous palladium/platinum (Pd/Pt) catalysts studied are part of a new range of heterogeneous catalysts developed at SiliCycle Inc for fine chemicals and pharmaceutical chemistry. These catalysts are synthesized from Pd/Pt nanoparticles (NPs) sequestered in the mesoporous cages of hydrophobic organosilicon support MeSiO₁, ₅. The hydrophobic nature of the catalysts is generated by the presence of the methyl groups of the methyltriethoxysilane silane (MTES) used as a monomer in the synthesis of the support. These heterogeneous catalysts, stable in air and moisture, have been found to be very reactive in many chemical reactions, especially under mild conditions of temperature and pressure, for example in carboncarbon coupling reactions, in hydrogenation reactions or in hydrosilylation reactions. The problem is that these catalysts proved to be reactive only for low metal contents (0.5 wt% Pd and 2.0 wt% Pt) and that their catalytic activity decreases considerably in the reusability test at high temperature and high pressure. Under these conditions the catalysts are no longer reusable. The main objective of this thesis is to make improvements to this class of hydrophobic catalysts in order to further increase their catalytic activity and their selectivity. Thus, novel heterogeneous catalytic materials stable to air and moisture have been developed. These catalysts are characterized by better mechanical resistence and stability of Pd/Pt NPs to sintering with high reuse capability under mild conditions, but also at high temperatures and pressures. Their catalytic activity has been evaluated in green applications with high industrial impact. The catalytic activity of Pd catalysts was evaluated in the hydrogenation of squalene to squalane, a fully saturated hydrocarbon, easily adopted by cosmetic formulators for its remarkable properties such as its high stability to oxidation, rancidity and heat. The catalytic activity of the Pt catalysts was evaluated in the hydrosilylation reaction, one of the most important methods for the synthesis of organosilicon compounds and particularly for the industrial scale production of organosilanes by addition of Si-H bonds to double bonds. First, the organosilicon support was doped with Al₂O₃ units. The new catalyst with Pd/Pt NPs encapsulated in the mesoporous cages of an organosilicic support doped with Al₂O₃ units, Pd⁰/MeSiO₁, ₅-Al₂O₃ and Pt⁰/MeSiO₁, ₅-Al₂O₃, have shown a high stability in air and humidity.
Miño, Andres. "Nouveaux supports mésostructurés pour la catalyse d’hydrotraitement." Thesis, Lille 1, 2012. http://www.theses.fr/2012LIL10151/document.
Hydrodesulfurization (HDS) catalysts are alumina supported (Ni) CoMo catalysts. HDS catalytic performance can be enhanced by the improvement of the properties of the industrial alumina carrier, Al2O3-γ. The synthesis of mesoporous alumina with templating agents used as carriers of HDS catalysts are studied. Two ways of alumina synthesis are presented: sol-gel (SG) and post synthesis modification (PSM). These alumina carriers exhibit improved textural properties compared to conventional alumina. These supports were impregnated with a solution of (Co2Mo10O38H4) Co3. The wetness impregnation step of these aluminas modifies their textural properties. A direct synthesis way (VD) of HDS catalysts, based on the synthesis of PSM aluminas but with the addition of the precursors of the active phase during the preparation of the support, is also developed. VD synthesis avoids textural modification properties of the alumina during the wetness impregnation step and also allows significant increase of the active phase content. The catalytic results in HDS of thiophene for solids of each family showed very interesting performance in comparison with that of conventional catalysts. The high performance SG and PSM catalysts as well as four VD catalysts (three with different pore diameters and one highly loaded) were shaped for straight run gas oil HDS (SRGO) test. The catalytic performances obtained are in most cases higher than those obtained for a reference catalyst and for the most efficient catalysts, were found unprecedented for HDS catalysts prepared without additives
Herry, Soazic. "Étude de l'activation de catalyseurs d'hydrodésulfuration des gazoles préparés par modification du précurseur oxyde." Lille 1, 2006. http://www.theses.fr/2006LIL10160.
The presence of heteroatoms such as sulphur is an atmospheric pollutant because of its combustion products. 2005 is important year with the application of Euro4 regulations, in the European Union, which allowed 50 ppm of sulphur in gasoline and diesel and in 2009 this will decrease to 10 ppm. This implies an optimization of HDS process as well as the improvement of HDS catalysts. One of way of study to improve HDS catalysts is to add organic compounds in the preparation of catalysts. The purpose of this work is to understand the role of these molecules on the oxidic precursors, on the activation step and on the active phase morphology. An activation study has thus been done, in both gas and liquid phases which completed by physico-chemical characterizations, and showed the main role of organic compounds. The characteristic evolution of metals during sulfidation induces an optimization of the active phase morphology which is in correlation with the improvement of the catalytics performances
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
Marrot, Sébastien. "Carbènes N-Hétérocycliques : Des catalyseurs en chimie des silicones. Carbodiphosphoranes cycliques : Synthèse, coordination et réactivité." Phd thesis, Toulouse 3, 2007. http://www.theses.fr/2007TOU30037.
In a first chapter, we are interested in the use of N-Heterocyclic Carbenes like nucleophilic organic catalysts for ring opening polymerization of octamethylcyclosiloxane and for reactions of polycondensation. In a second chapter, we carry out a bibliographical review on compounds presenting two cumulated ylides functions : carbodiphosphoranes. In a third chapter, we present the synthesis and the coordination of new cyclic carbodiphosphoranes. They are recognized to be strong s-donor ligands for transition metals. In a fourth chapter, we study the thermolysis of one of these compounds which leads by rearrangement to the formation of a 1,2l5-azaphosphète. A theoretical study highlights an inter-conversion between carbodiphosphoranes and disphosphinocarbenes
Haddad, Ryma. "Synthèse frugale de catalyseurs hétérogènes par procédé éco-responsable de chimie sol-gel sans solvants." Electronic Thesis or Diss., Sorbonne université, 2023. https://accesdistant.sorbonne-universite.fr/login?url=https://theses-intra.sorbonne-universite.fr/2023SORUS643.pdf.
Industry needs to move towards a sustainable economy, by reducing resources and energy consumptions and reducing waste production. Catalysis, especially through the use of catalysts, plays a key role in this transition. It significantly improves the energy efficiency of specific chemical reactions and selectively targeting their products. As a result, demand for catalysts has increased considerably due to environmental and energy concerns. To remain competitive, it is essential to optimise catalyst performance, catalytic processes and material properties, while reducing the energy and financial costs of their manufacture. This thesis aims to develop eco-responsible approaches for the large-scale manufacture of heterogeneous catalysts using solvent-free sol-gel chemistry coupled with mechanical mixing processes such as reactive extrusion. This strategy makes it possible to obtain high-performance catalytic materials while reducing their environmental impact. We will present a fundamental study that led to the description of the mechanisms involved in the synthesis of boehmite extrudates using solvent-free sol-gel chemistry coupled with the reactive extrusion process. The influence of material ageing parameters on the mechanical properties of the extrudates (necessary for a real industrial application) was also explored. Experiments were successfully carried out to create catalysts based on ruthenium and nickel supported on aluminium oxyhydoxide and alumina. The study shows that this "frugal" approach is competitive in terms of catalytic efficiency and much more sustainable than traditional methods
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
Bernardon, Claire. "Les zéolithes comme catalyseurs "verts" pour la synthèse organique : de leur synthèse à façon à leurs applications en chimie organique." Thesis, Strasbourg, 2016. http://www.theses.fr/2016STRAF017/document.
Zeolites are crystalline porous aluminosilicates and useful heterogeneous catalysts in chemical industries. They represent one of the significant solutions to main environmental concerns. Thanks to their particular properties like shape selectivity and intrinsic acidities of Lewis and Brønsted, zeolites offer unbeatable abilities in organic synthesis. More than 230 structures have already been discovered, which afford thousands discovery and offer a lot of possibilities.This work was focused on (i) a better understanding of zeolite crystallisation in the presence of an additional component from sugar industry, sugarcane bagasse; (ii) several characterization techniques have been used for a precise structure – properties understanding, mainly for their acidity; (iii) tailored-made catalysts have been tested in model reactions like Diels-Alder and Friedel-Crafts acylation. Hence, optimal catalysts exhibiting required properties could be prepared. This Thesis also aimed to explain zeolite crystallization thanks to sacrificial additional template.BEA, MFI, FAU and LTA zeolites have been prepared then optimized for catalytic testing in different reactions, while keeping in mind the Green Chemistry concept
Richard, Vincent. "Etudes des cycloadditions [2+2+2] ET [2+2+2+2] des yne-ynamides et leur application dans la synthèse de produits naturels." Caen, 2012. http://www.theses.fr/2013CAEN2003.
Catalysis by transition metals is a key element for the development of Green Chemistry, in particular for the decrease of waste, energy consumption, for its efficiency in atoms economy and its interest of an economic point of view. The efficiency of a process can be defined in terms of complexity, selectivity and economy of atom. Catalytic reactions can respect all these criteria simultaneously. So, the association of catalysis and organic chemistry allows to envisage new more economic and more ecological organic syntheses. An important aspect of this approach is the development of new ligands and/or catalysts, which allow to realize effective and selective reactions and the creation of original catalytic processes. During this work, we were interested in the cycloaddition reactions catalyzed by several organometallic complexes and involving in particular ynes-ynamides motives First of all, after a short presentation of this motive in organic synthesis, we developed a straightforward approach to - and -carbolines, tricyclic alkaloids possessing an indol framework, via a ruthenium- or rhodium-catalyzed [2+2+2] cycloaddition between an yne-ynamide and a nitrile derivative. Afterward we reported the synthesis of pyridine compounds via an iron-catalyzed [2+2+2] cycloaddition. Finally, in the last chapter, we started a program dedicated to nickel-catalyzed [2+2+2+2] cycloaddition and applied this methodology to the skeleton of Caulerpin
Souchon-Kammerer, Françoise. "Cyclisations induites par le palladium à partir de monoépoxydes de Cyclodiènes : une approche de la synthèse de la phyllanthocine." Aix-Marseille 3, 1997. http://www.theses.fr/1997AIX30032.
Wang, Weili. "De la catalyse homogène vers la catalyse hétérogène pour l'époxydation sans solvant à partir de (pré)catalyseurs du molybdène." Thesis, Toulouse 3, 2015. http://www.theses.fr/2015TOU30189/document.
The work of this PhD thesis deals with the study of molybdenum complexes of general formula [MoO2L]n (L being a tridentate Schiff base ligand with an ONO or ONS coordination sphere around the molybdenum) as catalysts for the organic solvent-free epoxidation of olefins. Within the spirit of Green Chemistry, the work has focused on four of the twelve Green Chemistry principles: the use of catalysis rather than stoichiometric transformations, the use of organic solvent-free procedures rather than operating in solution of organic solvents, the use of renewable substrates and the grafting of catalysts for their recovery. The first part of the manuscript presents a concise state of the art on the chemistry of molybdenum complexes with ligands similar to those used within the thesis. Specific aspects such as the effect of ligand substituents and the different activities - mainly catalytic - observed in organic media are reviewed. A section of this chapter is dedicated to the different strategies employed for the grafting of molybdenum complexes to solid supports as well as to the use of the resulting supported complexes in heterogenized homogeneous catalysis. The next chapter details the synthesis and characterization of all the molecular complexes used as catalysts. This chapter shows the different substitutions operated on the ligands, i.e. changing the ONO coordination sphere to ONS and adding different substituents on the ligands, i.e. OH free functions or additional donor (diethylamino) and/or withdrawing (nitro) substituents at different positions on the tridentate ligand in order to modify the catalytic activity. Six of the synthesized complexes could be characterized by X-ray crystallography. The third chapter reports the results obtained for the catalyzed organic solvent-free epoxidation of cyclooctene as a model substrate using all the molybdenum complexes presented in the previous chapter. It is shown that the nature of the coordination sphere around the molybdenum (ONO vs ONS) is in favour of the latter in terms of catalytic activity towards the formation of the desired epoxide. The catalyzed reactions with complexes containing an OH substituent at different positions on the aromatic ring have shown more significant effects in the case of the ONO coordination sphere than in the corresponding ONS case. The epoxidation performed in the presence of a dimethylamino and/or a nitro substituent on the ONO ligand revealed that the catalytic activity is enhanced by the electron withdrawing group. The catalytic investigations were pursued by the epoxidation of cyclohexene and of one natural substrate, limonene. This study has shown that limonene oxides and/or limonene diols are generated, depending on the nature of the catalyst. The ONS complexes are very reactive and quickly lead to the limonene diols. The effect of different parameters has been studied with particular attention to the reaction temperature. Finally, one stable molybdenum complex with an ONO coordination sphere has been grafted onto a commercial Merrifield resin. Different grafting strategies are presented. The isolated objects have been tested as catalysts under organic solvent-free conditions for the epoxidation of cyclooctene. The catalytic results are promising in terms of activity and the recovery/recycling tests have shown that the catalysts could be used three times without significant decrease of conversion and selectivity, but some metal leaching was observed
Kuhn, Philippe. "Zéolithes et chimie organique : Elaboration de nouvelles voies de synthèses vertes." Strasbourg, 2011. https://publication-theses.unistra.fr/public/theses_doctorat/2011/KUHN_Philippe_2011.pdf.
The work presented in this manuscript relates the application of zeolites in organic chemistry. Used in their acidic form or doped with copper(I) cations, to exhibit coupling properties, they exhibit a high efficiency and flexibility. Those acids, are easy to handle and well indicated in green chemistry. The development of a new chlorination system, using zeolites and trichloroisocyanuric acid (TCCA), has been studied. A variety of aromatics, activated or not, has been chlorinated with this system. The first method, in liquid/solid phase, allows chlorination of activated or weakly activated aromatics. The second, in solid/gas and in continuous flow, in a plug-flow reactor, allows to avoid temperature limitation due to the use of solvents. This method is able to chlorinate strong deactivated aromatics such as nitrobenzene. Doping zeolites with copper(I) creates a heterogeneous catalyst which exhibits functionality provided by zeolites themselves and copper(I) cations. Those functionalities are useful in Glaser coupling reaction (alkyne homocoupling). Preparation followed by multiple characterizations allow us to target more efficiently properties of copper(I) doped zeolites. The elaborated synthesis provides extraction and manipulation facilities and also good to excellent yields in homocoupling products
Gergely, Bernadett. "Synthèse et caractérisation de catalyseurs à base d'oxyde d'étain et de gallium." Lyon 1, 2001. http://www.theses.fr/2001LYO10166.
Gaval, Pooja. "Catalyseurs pour la synthèse du butadiène via le procédé Ostromyslensky développés par Chimie organométallique de surface." Thesis, Lyon, 2018. http://www.theses.fr/2018LYSE1315/document.
In the recent years on-purpose synthesis of butadiene using bioethanol has gained unprecedented attention owing to rise in interest for bio-based feedstock along with the steeply increasing demand for butadiene (BD). In this regard a relevant process is the Ostromyslensky’s two-step process, involving dehydrogenation of ethanol to acetaldehyde in a separate step, followed by butadiene production in the second stage by co-feeding ethanol and acetaldehyde. Although the economic viability and feasibility of this ethanol to butadiene (ETB) process is well established, there is a room for better catalytic performances and selectivity. In this endeavour our aim was to develop a family of well-defined Ta-based silica-supported catalysts through Surface Organometallic Chemistry (SOMC) and test them in the conversion of EtOH/AA to BD. The first set of pre-catalysts was synthesized by treating the previously known [(=SiO)2TaHx] with N2O as mild oxidant. The second family of catalysts was prepared by calcination of the tantalum alkyl species at 500°C. The pre-catalysts were characterized by FTIR, SS NMR, UV-vis-DRS, XRD, EXAFS and HR-STEM. The N2O oxidized SOMC pre-catalysts were found to have mostly isolated [(=SiO)2Ta(OH)x] species populating the surface whereas the family of pre-catalysts synthesized via calcination evidenced a mixture of surface species, including string-like aggregations.Catalytic tests over these catalysts generated promising results exhibiting superior catalysis in the transformation of EtOH/AA to BD in terms of both BD selectivity and yield compared to the state of the art. In addition to the excellent selectivity a narrow range of product distribution and negligible coke formation was observed. Isolated TaOx species on the N2O oxidized pre-catalyst showed markedly better activity and were found to be the active sites in this conversion compared to the string-like aggregation of tantalum centres on the calcined material. Based on this and in-situ DRIFT studies over the catalysts a preliminary mechanism for this conversion was proposed
Mistico, Laëtitia. "Synthèse de nouveaux hétérocycles silylés par réarrangement anionique ou par activation C-H." Rouen, 2014. http://www.theses.fr/2014ROUES047.