The Experts below are selected from a list of 300 Experts worldwide ranked by ideXlab platform
Raymond J Gorte - One of the best experts on this subject based on the ideXlab platform.
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influence of bronsted acid and cation exchange sites on ethene adsorption in zsm 5
Microporous and Mesoporous Materials, 2019Co-Authors: Christopher Rzepa, Srinivas Rangarajan, Raymond J GorteAbstract:Abstract Differential heats of adsorption were measured for Ethane and ethene on a siliceous ZSM-5, H-[Al]ZSM-5, H-[Fe]ZSM-5, Li-[Al]ZSM-5, H(Zn)-[Al]ZSM-5, and H(Zn)-[Fe]ZSM-5 at 195 K in order to characterize the nature of interactions between the olefin functional group and both Bronsted sites and exchanged metal cations. On siliceous ZSM-5, the differential heats for Ethane and ethene were both 31 ± 1 kJ/mol, independent of coverage. While the additional interaction of Ethane with Li and Zn-cation sites was negligible and only about 2 kJ/mol with Bronsted sites, the additional heats of adsorption for ethene were negligible on Li sites, 8 kJ/mol on Bronsted sites, and 14 kJ/mol Zn sites. Results were similar for exchanged [Al]ZSM-5 and [Fe]ZSM-5. Density functional theory calculations with different dispersion-corrected generalized gradient approximation functionals correctly predict the increased interaction of ethene with acid sites but overestimate the strength of interaction of proton and Li with C C double bonds.
David Willock - One of the best experts on this subject based on the ideXlab platform.
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Partial oxidation of Ethane to oxygenates using Fe- and Cu-containing ZSM-5
Journal of the American Chemical Society, 2013Co-Authors: Michael M. Forde, Robert D. Armstrong, Ceri Hammond, Robert L. Jenkins, Stuart H. Taylor, Sergeevich Aleksandr Kondrat'ev, Nikolaos Dimitratos, Jose Antonio Lopez-sanchez, Qian He, David WillockAbstract:Iron and copper containing ZSM-5 catalysts are effective for the partial oxidation of Ethane with hydrogen peroxide giving combined oxygenate selectivities and productivities of up to 95.2% and 65 mol kgcat(-1) h(-1), respectively. High conversion of Ethane (ca. 56%) to acetic acid (ca. 70% selectivity) can be observed. Detailed studies of this catalytic system reveal a complex reaction network in which the oxidation of Ethane gives a range of C2 oxygenates, with sequential C-C bond cleavage generating C1 products. We demonstrate that ethene is also formed and can be subsequently oxidized. Ethanol can be directly produced from Ethane, and does not originate from the decomposition of its corresponding alkylperoxy species, ethyl hydroperoxide. In contrast to our previously proposed mechanism for mEthane oxidation over similar zeolite catalysts, the mechanism of Ethane oxidation involves carbon-based radicals, which lead to the high conversions we observe.
Stefan Reimann - One of the best experts on this subject based on the ideXlab platform.
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Discrepancy between simulated and observed Ethane and propane levels explained by underestimated fossil emissions
Nature Geoscience, 2018Co-Authors: Stig B. Dalsøren, Detlev Helmig, Gunnar Myhre, Øivind Hodnebrog, Cathrine Lund Myhre, Andreas Stohl, Ignacio Pisso, Stefan Schwietzke, Lena Höglund-isaksson, Stefan ReimannAbstract:Observations of Ethane and propane distributions in the atmosphere are reproduced in simulations with an atmospheric chemistry transport model, if fossil emissions are a factor of two to three higher than previously assumed. Ethane and propane are the most abundant non-mEthane hydrocarbons in the atmosphere. However, their emissions, atmospheric distribution, and trends in their atmospheric concentrations are insufficiently understood. Atmospheric model simulations using standard community emission inventories do not reproduce available measurements in the Northern Hemisphere. Here, we show that observations of pre-industrial and present-day Ethane and propane can be reproduced in simulations with a detailed atmospheric chemistry transport model, provided that natural geologic emissions are taken into account and anthropogenic fossil fuel emissions are assumed to be two to three times higher than is indicated in current inventories. Accounting for these enhanced Ethane and propane emissions results in simulated surface ozone concentrations that are 5–13% higher than previously assumed in some polluted regions in Asia. The improved correspondence with observed Ethane and propane in model simulations with greater emissions suggests that the level of fossil (geologic + fossil fuel) mEthane emissions in current inventories may need re-evaluation.
Christopher Rzepa - One of the best experts on this subject based on the ideXlab platform.
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influence of bronsted acid and cation exchange sites on ethene adsorption in zsm 5
Microporous and Mesoporous Materials, 2019Co-Authors: Christopher Rzepa, Srinivas Rangarajan, Raymond J GorteAbstract:Abstract Differential heats of adsorption were measured for Ethane and ethene on a siliceous ZSM-5, H-[Al]ZSM-5, H-[Fe]ZSM-5, Li-[Al]ZSM-5, H(Zn)-[Al]ZSM-5, and H(Zn)-[Fe]ZSM-5 at 195 K in order to characterize the nature of interactions between the olefin functional group and both Bronsted sites and exchanged metal cations. On siliceous ZSM-5, the differential heats for Ethane and ethene were both 31 ± 1 kJ/mol, independent of coverage. While the additional interaction of Ethane with Li and Zn-cation sites was negligible and only about 2 kJ/mol with Bronsted sites, the additional heats of adsorption for ethene were negligible on Li sites, 8 kJ/mol on Bronsted sites, and 14 kJ/mol Zn sites. Results were similar for exchanged [Al]ZSM-5 and [Fe]ZSM-5. Density functional theory calculations with different dispersion-corrected generalized gradient approximation functionals correctly predict the increased interaction of ethene with acid sites but overestimate the strength of interaction of proton and Li with C C double bonds.
Kamil Klier - One of the best experts on this subject based on the ideXlab platform.
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Selective oxidation of mEthane with air over silica catalysts
Catalysis Letters, 1992Co-Authors: Richard G. Herman, Kamil KlierAbstract:Partial oxidation of mEthane by oxygen to form formaldehyde, carbon oxides, and C_2 products (Ethane and ethene) has been studied over silica catalyst supports (fumed Cabosil and Grace 636 silica gel) in the 630–780 °C temperature range under ambient pressure. The silica catalysts exhibit high space time yields (at low conversions) for mEthane partial oxidation to formaldehyde, and the C_2 hydrocarbons were found to be parallel products with formaldehyde. Short residence times enhanced both the C_2 hydrocarbons and formaldehyde selectivities over the carbon oxides even within the differential reactor regime at 780 °C. This suggests that the formaldehyde did not originate from methyl radicals, but rather from methoxy complexes formed upon the direct chemisorption of mEthane at the silica surface at high temperature. Very high formaldehyde space time yields (e.g., 812 g/kg cat h at the gas hourly space velocity = 560 000 ℓ(NTP)/kg cat h) could be obtained over the silica gel catalyst at 780 °C with a mEthane/air mixture of 1.5/1. These yields greatly surpass those reported for silicas earlier, as well as those over many other catalysts. Low CO_2 yields were observed under these reaction conditions, and the selectivities to formaldehyde and C_2 hydrocarbons were 28.0 and 38.8%, respectively, at a mEthane conversion of 0.7%. A reaction mechanism was proposed for the mEthane activation over the silica surface based on the present studies, which can explain the product distribution patterns (specifically the parallel formation of formaldehyde and C_2 hydrocarbons).