984 resultados para Methanol dehydrogenation


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The molecule of title compound, C11H10ClNO, is close to being planar (r.m.s deviation for the non-H atoms = 0.017 angstrom). In the crystal, molecules interact by way of O-H center dot center dot center dot O hydrogen bonds, generating C(2) chains propagating in [010]. The crystal structure is consolidated by C-H center dot center dot center dot pi interactions and aromatic pi-pi stacking interactions [centroid-centroid distance = 3.661 (2) angstrom].

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The title compound, C11H10ClNO, is close to being planar (r.m.s deviation for the non-H atoms = 0.026 angstrom). In the crystal,molecules are linked by O-H center dot center dot center dot O hydrogen bonds, generating C(2) chains, and weak C-H center dot center dot center dot pi interactions and aromatic pi-pi stacking interactions [centroid-centroid distance = 3.713 (3) angstrom] help to consolidate the sturcture.

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Dehydrogenation of ammonia borane was carried out in fluor alcohol solvent in order to obtain compounds that are more likely candidates suitable for regeneration. Even though ammonia borane undergoes self-dissociation in 2,2,2-trifluoroethanol to liberate H-2, decent hydrogen release rates were obtained by using Co-Co2B, Ni-Ni3B, and Co-Ni-B nanocomposites as catalysts. These catalysts are magnetic in nature and hence can be separated from the reaction mixture using a magnet for re-use. The final by-product NH4+ B(OCH2CF3)(4)(-) obtained after the catalytic dehydrogenation of ammonia borane was thoroughly characterized using H-1, B-11, and C-13 NMR and IR spectroscopies. The FTIR data showed that the B-O bond in NH4+ B(OCH2CF3)(4)(-) is slightly weaker compared to boric acid. Preliminary investigations on the regenerative routes for ammonia borane from the by-product NH4+ B(OCH2CF3)(4)(-) showed indications of the formation of BNHx species. (C) 2010 Professor T. Nejat Veziroglu. Published by Elsevier Ltd. All rights reserved.

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In the present study, titanium nitride which shows exceptional stability, extreme corrosion resistance, good electronic conductivity and adhesion behaviour is used to support platinum particles and then used for methanol oxidation in an alkaline medium. The catalyst shows very good CO tolerance for the electrochemical oxidation of methanol. In situ infrared spectroelectrochemical data show the remarkable ability of TiN to decompose water at low over potentials leading to -OH type functional groups on its surface which in turn help in alleviating the carbon monoxide poisoning associated with methanol oxidation. TiN supported catalysts are found to be very good in terms of long term stability, exchange current density and stable currents at low over voltages. Supporting evidence from X-ray photoelectron spectroscopic data and cyclic voltammetry clearly demonstrates the usefulness of TiN supported Pt catalysts for efficient methanol oxidation in alkaline media.

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A fully automated, versatile Temperature Programmed Desorption (TDP), Temperature Programmed Reaction (TPR) and Evolved Gas Analysis (EGA) system has been designed and fabricated. The system consists of a micro-reactor which can be evacuated to 10−6 torr and can be heated from 30 to 750°C at a rate of 5 to 30°C per minute. The gas evolved from the reactor is analysed by a quadrupole mass spectrometer (1–300 amu). Data on each of the mass scans and the temperature at a given time are acquired by a PC/AT system to generate thermograms. The functioning of the system is exemplified by the temperature programmed desorption (TPD) of oxygen from YBa2Cu3−xCoxO7 ± δ, catalytic ammonia oxidation to NO over YBa2Cu3O7−δ and anaerobic oxidation of methanol to CO2, CO and H2O over YBa2Cu3O7−δ (Y123) and PrBa2Cu3O7−δ (Pr123) systems.

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A recently developed microscopic theory of solvation dynamics in real dipolar liquids is used to calculate, for the first time, the solvation time correlation function in liquid acetonitrile, water and methanol. The calculated results are in excellent agreement with known experimental and computer simulation studies.

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Electrooxidation of methanol in sulphuric acid on carbon-supported electrodes containing Pt-Sn bimetal catalysts prepared by an in-situ route is reported, The catalysts have been characterized employing chemical analyses, XRD, and XANES data in conjunction with electrochemistry. This study suggests that the Sn content in Pt-Sn bimetals produces: (i) a charge transfer from Sn to Pt and (ii) an increase in the coverage of adsorbed methanolic residues with the Sn content. From the electrode-kinetics data, it is inferred that while the electrodes of (3:3) Pt-Sn/C catalyst involve a 2-electron rate-limiting step akin to Pt/C electrodes, it is shifted to only 1-electron on (3:2) Pt-Sn/C, (3:3) Pt-Sn/C, and (3:4) Pt-Sn/C electrodes.

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The polyvinylidene fluoride (PVDF) membrane is modified by the chemical etchant-route employing a sodium naphthalene charge-transfer complex followed by impregnation with Nafion ionomer or polyvinyl alcohol (PVA)-polystyrene sulfonic acid (PSSA) polymeric blend solutions by a dip-coating technique to form pore-filled-membrane electrolytes for application in direct methanol fuel cells (DMFCs). The number of coatings on the surface-modified PVDF membrane is varied between 5 and 15 and is found to be optimum at 10 layers both for Nafion and PVA-PSSA impregnations for effective DMFC performance. Hydrophilicity of the modified-membrane electrolytes is studied by determining average contact angle and surface-wetting energy. Morphology of the membranes is analyzed by a cross-sectional scanning electron microscope. The modified PVDF membrane electrolytes are characterized for their water-methanol sorption in conjunction with their mechanical properties, proton conductivity, and DMFC performance. Air permeability for the modified membranes is studied by a capillary-flow porometer. Methanol crossover flux across modified-PVDF-membrane electrolytes is studied by measuring the mass balance of methanol using a density meter. DMFCs employing membrane electrode assemblies with the modified PVDF membranes exhibit a peak power-density of 83 mW/cm(2) with Nafion impregnation and 59 mW/cm(2) for PVA-PSSA impregnation, respectively. Among the membranes studied here, stabilities of modified-pore-filled PVDF-Nafion and PVDF-PVA-PSSA membranes with 10-layers coat are promising for application in DMFCs. (C) 2010 The Electrochemical Society. DOI: 10.1149/1.3518774] All rights reserved.

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The oxidative dehydrogenation of ethylbenzene is gaining considerable importance in recent years as a promising alternative for styrene production. This vapour phase reaction has been studied over Pd-NaBr/Al2O3 catalyst in the temperature range 623-793 K in a fixed bed reactor. Kinetic analysis of this reaction has been done using a recursion procedure developed in this work from first principles. The advantage of this method is the absence of any restriction on the conversion level as it uses an integrated rate equation. The rate of styrene formation was found to follow a linear relationship with concentration of ethylbenzene and shows a Langmuir type dependence on the concentration of oxygen.

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The effect of acid/base functional-groups associated with platinized-carbon electrodes on their catalytic activity toward electro-oxidation of methanol in sulfuric acid electrolyte at 60-degrees-C is studied. Platinized-carbon electrodes with sm amounts of functional groups exhibit higher catalytic activity compared to those with large concentrations of acidic/basic surface functionalities. The overpotential for methanol oxidation is minimum on electrodes of platinized carbons with pHzpc values between 6 and 7. An x-ray photoelectron spectroscopic study of various platinized carbons suggests that the acid/base surface functional-groups produce ample amounts of surface Pt-oxides and a consequent decrease in activity toward methanol oxidation.