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Rh promoted perovskites for exceptional “low temperature” methane conversion to syngas
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Ethylene production by direct conversion of methane over isolated single active centers
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Hydrokinetic power conversion using Flow Induced Vibrations with nonlinear (adaptive piecewise-linear) springs
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Hydrokinetic power conversion using Flow Induced Vibrations with cubic restoring force
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Tandem Lewis acid/Brønsted acid-catalyzed conversion of carbohydrates to 5-hydroxymethylfurfural using zeolite beta
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The origin of selectivity in the conversion of glucose to fructose and mannose in Sn-BEA and Na-exchanged Sn-BEA zeolites
We investigate the isomerization and epimerization of glucose to fructose and mannose in Sn-BEA andNa-exchanged Sn-BEA using density-functional theory calculations on periodic BEA crystals. We comparereaction pathways both in the absence and presence of water molecules in the vicinity of the active siteand find that water effectively determines the selectivity in Na-Sn-BEA. We identify two competingepimerization pathways, one involving direct 1,2-carbon shift and the other involving 1,2-hydride shiftvia fructose. In Sn-BEA, the isomerization to fructose is the kinetically dominant pathway, while mannoseis formed via the indirect 1,2-hydride shift epimerization pathway. In Na-Sn-BEA, the kinetically domi-nant pathway is epimerization to mannose via the direct 1,2-carbon shift pathway (Bilik mechanism)only in the presence of water solvent in the vicinity of the active site, whereas isomerization is preferredin the absence of water. We argue that polar water molecules that coordinate around the Na cation screenstrong electrostatic interactions between Na+and the glucose backbone that are responsible for thestrong inhibition of the 1,2-carbon shift mechanism in the absence of water. In Sn-BEA, the presenceof water does not influence the selectivity. Our calculations resolve for the first time the role of waterand Na cations in the catalytic activity of Sn-BEA, and rationalize the experimental data.
Electrochemical conversion of CO2 to formic acid utilizing Sustainion™ membranes
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Evolution of chromium, manganese and iron oxidation state during conversion of nuclear waste melter feed to molten glass
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Conversion of nuclear waste to molten glass: Formation of porous amorphous alumina in a high-Al melter feed
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