The Experts below are selected from a list of 15534 Experts worldwide ranked by ideXlab platform
Veronique Van Speybroeck - One of the best experts on this subject based on the ideXlab platform.
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insight into the formation and reactivity of framework bound Methoxide species in h zsm 5 from static and dynamic molecular simulations
Chemcatchem, 2014Co-Authors: Jeroen Van Der Mynsbrugge, Samuel L. C. Moors, Kristof De Wispelaere, Veronique Van SpeybroeckAbstract:Framework-bound Methoxides occur as intermediates in the stepwise mechanism for zeolite-catalyzed methylation reactions. Herein, the formation of Methoxides from methanol or dimethyl ether in H-ZSM-5 is investigated by a combination of static and dynamic simulations, with particular focus on the effect of additional water and methanol molecules on the mechanism and kinetics. Metadynamics simulations allow partitioning the reaction path into distinct phases. Proton transfer from the zeolite to the reactants is found to be the rate-limiting phase in the Methoxide formation. Additional methanol molecules only assist the proton transfer in the Methoxide formation from methanol, whereas the reaction from dimethyl ether does not benefit from methanol assistance. Once formed, Methoxides are found to be as reactive toward alkene methylation as methanol and dimethyl ether.
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Insight into the Formation and Reactivity of Framework‐Bound Methoxide Species in H‐ZSM‐5 from Static and Dynamic Molecular Simulations
ChemCatChem, 2014Co-Authors: Jeroen Van Der Mynsbrugge, Samuel L. C. Moors, Kristof De Wispelaere, Veronique Van SpeybroeckAbstract:Framework-bound Methoxides occur as intermediates in the stepwise mechanism for zeolite-catalyzed methylation reactions. Herein, the formation of Methoxides from methanol or dimethyl ether in H-ZSM-5 is investigated by a combination of static and dynamic simulations, with particular focus on the effect of additional water and methanol molecules on the mechanism and kinetics. Metadynamics simulations allow partitioning the reaction path into distinct phases. Proton transfer from the zeolite to the reactants is found to be the rate-limiting phase in the Methoxide formation. Additional methanol molecules only assist the proton transfer in the Methoxide formation from methanol, whereas the reaction from dimethyl ether does not benefit from methanol assistance. Once formed, Methoxides are found to be as reactive toward alkene methylation as methanol and dimethyl ether.
Irving Wender - One of the best experts on this subject based on the ideXlab platform.
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slurry phase synthesis of methanol with a potassium Methoxide copper chromite catalytic system
Applied Catalysis A-general, 1993Co-Authors: Vishwesh M. Palekar, Heon Jung, John W. Tiemey, Irving WenderAbstract:Abstract The use of methanol as a fuel additive and in methyl t-butyl ether (MTBE) production has renewed interest in the search for improved methanol processes. A slurry phase concurrent synthesis of methanol using a potassium Methoxide/copper chromite mixed catalyst which operates under relatively mild conditions (100–180°C, 30–65 atm) is described. The reaction pathway likely involves a homogeneous carbonylation of methanol to methyl formate followed by the heterogeneous hydrogenolysis of methyl formate to two molecules of methanol - the net result being the reaction of hydrogen with carbon monoxide to give methanol via methyl formate. The copper chromite also catalyzes the regeneration of the potassium Methoxide catalyst in solution from potassium formate and potassium methyl carbonate resulting in tolerance to small amounts of water and carbon dioxide. A synergistic effect between the potassium Methoxide and copper chromite results in high rates of methanol formation in the concurrent synthesis.
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Slurry phase synthesis of methanol with a potassium Methoxide/copper chromite catalytic system
Applied Catalysis A: General, 1993Co-Authors: Vishwesh M. Palekar, Heon Jung, John W. Tiemey, Irving WenderAbstract:Abstract The use of methanol as a fuel additive and in methyl t-butyl ether (MTBE) production has renewed interest in the search for improved methanol processes. A slurry phase concurrent synthesis of methanol using a potassium Methoxide/copper chromite mixed catalyst which operates under relatively mild conditions (100–180°C, 30–65 atm) is described. The reaction pathway likely involves a homogeneous carbonylation of methanol to methyl formate followed by the heterogeneous hydrogenolysis of methyl formate to two molecules of methanol - the net result being the reaction of hydrogen with carbon monoxide to give methanol via methyl formate. The copper chromite also catalyzes the regeneration of the potassium Methoxide catalyst in solution from potassium formate and potassium methyl carbonate resulting in tolerance to small amounts of water and carbon dioxide. A synergistic effect between the potassium Methoxide and copper chromite results in high rates of methanol formation in the concurrent synthesis.
Jeroen Van Der Mynsbrugge - One of the best experts on this subject based on the ideXlab platform.
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insight into the formation and reactivity of framework bound Methoxide species in h zsm 5 from static and dynamic molecular simulations
Chemcatchem, 2014Co-Authors: Jeroen Van Der Mynsbrugge, Samuel L. C. Moors, Kristof De Wispelaere, Veronique Van SpeybroeckAbstract:Framework-bound Methoxides occur as intermediates in the stepwise mechanism for zeolite-catalyzed methylation reactions. Herein, the formation of Methoxides from methanol or dimethyl ether in H-ZSM-5 is investigated by a combination of static and dynamic simulations, with particular focus on the effect of additional water and methanol molecules on the mechanism and kinetics. Metadynamics simulations allow partitioning the reaction path into distinct phases. Proton transfer from the zeolite to the reactants is found to be the rate-limiting phase in the Methoxide formation. Additional methanol molecules only assist the proton transfer in the Methoxide formation from methanol, whereas the reaction from dimethyl ether does not benefit from methanol assistance. Once formed, Methoxides are found to be as reactive toward alkene methylation as methanol and dimethyl ether.
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Insight into the Formation and Reactivity of Framework‐Bound Methoxide Species in H‐ZSM‐5 from Static and Dynamic Molecular Simulations
ChemCatChem, 2014Co-Authors: Jeroen Van Der Mynsbrugge, Samuel L. C. Moors, Kristof De Wispelaere, Veronique Van SpeybroeckAbstract:Framework-bound Methoxides occur as intermediates in the stepwise mechanism for zeolite-catalyzed methylation reactions. Herein, the formation of Methoxides from methanol or dimethyl ether in H-ZSM-5 is investigated by a combination of static and dynamic simulations, with particular focus on the effect of additional water and methanol molecules on the mechanism and kinetics. Metadynamics simulations allow partitioning the reaction path into distinct phases. Proton transfer from the zeolite to the reactants is found to be the rate-limiting phase in the Methoxide formation. Additional methanol molecules only assist the proton transfer in the Methoxide formation from methanol, whereas the reaction from dimethyl ether does not benefit from methanol assistance. Once formed, Methoxides are found to be as reactive toward alkene methylation as methanol and dimethyl ether.
Alan L Balch - One of the best experts on this subject based on the ideXlab platform.
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models for verdoheme hydrolysis paramagnetic products from the ring opening of verdohemes 5 oxaporphyrin complexes of iron ii with Methoxide ion
Journal of the American Chemical Society, 1998Co-Authors: Richard Koerner, And Lechosolaw Latosgrazynski, Alan L BalchAbstract:Studies of the reaction of 5-oxaporphyrin iron complexes (verdohemes) with Methoxide ion have been undertaken to provide models for the initial step in hydrolysis of verdohemes. Treatment of both low-spin [(py)2FeII(OEOP)]Cl and high-spin {ClFeII(OEOP)} (OEOP is the monoanion of octaethyl-5-oxaporphyrin) with Methoxide ion in either pyridine or methanol solution is shown to cause ring opening and addition of Methoxide to one end of the tetrapyrrole. Black {FeII(OEBOMe)}2 has been isolated in crystalline form from the reaction of {ClFeII(OEOP)} with Methoxide in methanol and studied by single-crystal X-ray diffraction. The molecule has a centrosymmetric dimeric structure composed of two helical Fe(OEBOMe) units with FeN4 coordination which are connected by a pair of Fe−O bonds. Each iron ion has approximately trigonal bipyramidal geometry. Evidence is presented which suggests that {FeII(OEBOMe)}2 dissolves in dichloromethane in the presence of methanol or pyridine to form high-spin {(MeOH)nFeII(OEBOMe)} or...
Kok Hwa Lim - One of the best experts on this subject based on the ideXlab platform.
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Effects of strain on PdZn(1 0 0) for Methoxide decomposition: A DFT study
Journal of Molecular Catalysis A: Chemical, 2014Co-Authors: Rern Jern Lim, Jong-min Lee, Xin Wang, Kok Hwa LimAbstract:Abstract Density functional theory has been used to systematically investigate the adsorption of Methoxide and its decomposed intermediates (i.e. H, O, CH3 and CH2O) as well as Methoxide decomposition reaction on strained PdZn(1 0 0) surfaces. The reaction and activation energies of Methoxide C H and C O bond breaking process showed that expansive strain increased the activity of the PdZn(1 0 0) surface toward Methoxide decomposition, but reduced its selectivity.
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Density Functional Study of the Effects of Strains on the Adsorption of Methoxide and its Decomposed Intermediates on Cu(100) Surface
Catalysis Letters, 2008Co-Authors: Agnes S. Y. Foo, Kok Hwa LimAbstract:Periodic density functional slab models were used to investigate adsorption of Methoxide and its decomposed intermediates on optimized and strained (−5% to +5%) Cu(100) surfaces. Surface relaxation energies and adsorption energies of Methoxide and its decomposed intermediates were systematically studied and quantified. Reaction energetics of Methoxide C–H and C–O bond breaking were quantified on the strained Cu(100) surfaces.
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Density functional study of Methoxide decomposition on PdZn(100)
Phys. Chem. Chem. Phys., 2004Co-Authors: Zhao-xu Chen, Kok Hwa Lim, Konstantin M. Neyman, Notker RöschAbstract:Reactants, products and transition state species involved in the decomposition of Methoxide, CH3O to CH2O + H and CH3 + O fragments on the PdZn(100) surface have been studied theoretically. We used periodic slab models and a density functional method and compared our results to those for the corresponding complexes on the more compact PdZn(111) surface investigated earlier. On PdZn(100), both C–H and C–O bond scission reactions of CH3O were found to be somewhat more endothermic than on the (111) surface. Transition state structures for both cleavage reactions are similar to their PdZn(111) analogues. Similarly to PdZn(111), C–H bond scission of Methoxide is kinetically favored on PdZn(100) over C–O bond breaking. However, even the activation barrier for C–H bond breaking on PdZn(100) surface is rather high. Thus, defects most probably are responsible for Methoxide decomposition on PdZn catalysts.
