Search results for "dehydrogenation"

Nickel oxide supported on porous clay heterostructures as selective catalysts for the oxidative dehydrogenation of ethane

2016

[EN] Porous clay heterostructures (PCH) have shown to be highly efficient supports for nickel oxide in the oxidative dehydrogenation of ethane. Thus NiO supported on silica with a PCH structure shows productivity towards ethylene three times higher than if NiO is supported on a conventional silica. This enhanced productivity is due to the increase in the catalytic activity and especially to the drastic increase in the selectivity to ethylene. Additionally, PCH silica partially modified with titanium in the columns (PCH-Ti) have also been synthesized and used as supports for NiO. An enhanced activity and selectivity to ethylene was found over NiO supported over PCH-Ti compared to the corresp…

DFT study on complete ethylene decomposition on flat and stepped Pd

2010

Abstract We applied density functional theory (DFT) calculations to study ethylidyne (CCH 3 ) adsorption and decomposition to C and H over flat and stepped Pd surfaces. Our calculations show that ethylidyne is the most stable molecule among all the possible dehydrogenation or decomposition residues of ethylene. We discuss various possible reaction pathways for ethylidyne decomposition and point out that the most probable one is via ethynyl (CCH) species suggested also by experimental observations. Our calculations indicate that the presence of steps modify the potential energy surface by increasing the binding of most of the species, and also lowering the activation barrier for several reac…

Effect of silver deposits on the photocatalytic activity of titanium dioxide samples for the dehydrogenation or oxidation of 2-propanol

1991

Abstract Until now, the effect of the deposition of metal particles onto a powdered semiconductor oxide on its photocatalytic activity has been determined for group VIII transition metals only. In this study, AGTiO2 samples were prepared by photodeposition, characterized by transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) and tested, under band-gap illumination, using the oxidation of 2-propanol (neat liquid phase or mixed with water) in the absence or presence of molecular oxygen. The silver deposits were found to be metallic both before and after use, but the size of the particles and their distribution on the support were markedly influenced by the type …

Synthesis of 2,3‐Dihydro‐4‐pyridones, 4‐Quinolones, and 2,3‐Dihydro‐4‐azocinones by Visible‐Light Photocatalytic Aerobic Dehydrogenation

2019

Optimal hydrogen storage in sodium substituted lithium fullerides

2017

Through the substitution of Li with Na in Li6C60, we synthesized a series of mixed alkali cluster intercalated fullerides, NaxLi6−xC60. These compounds share lattices of Na6C60 and Li6C60 with a cubic parameter linearly dependent on x. H2 absorption and desorption were studied by means of charge/discharge kinetic measurements and coupled calorimetric–manometric evaluation. By varying the stoichiometry, we found the best compromise among the absorption rate, temperature and amount of hydrogen for x = 0.5 and 1. Small concentrations of Na substituted to Li significantly lower the absorption temperature of Li6C60, improving the hydrogenation capacity, the kinetics, and the dehydrogenation enth…

Experimental investigation on lithium borohydride hydrolysis

2010

Abstract Lithium borohydride, one of the highest energy density chemical energy carriers, is considered as an attractive potential hydrogen storage material due to its high gravimetric hydrogen density (19.6%). Belonging to borohydride compounds, it presents a real issue to overcome aims fixed by the U.S. Department of Energy in the field of energy, and so crystallizes currently attention and effort to use this material for large scale civil and military applications. However, due to its important hygroscopicity, lithium borohydride is a hazardous material which requires specific handling conditions for industrial aspects. In order to understand much more the reaction mechanism involved bet…

Arylated phenols, aroxyl radicals and aryloxenium ions syntheses and properties

1985

ChemInform Abstract: Cross-Dehydrogenative Couplings Between Indoles and β-Keto Esters: Ligand-Assisted Ligand Tautomerization and Dehydrogenation vi…

2014

Cross-dehydrogenative coupling reactions between β-ketoesters and electron-rich arenes, such as indoles, proceed with high regiochemical fidelity with a range of β-ketoesters and indoles. The mechanism of the reaction between a prototypical β-ketoester, ethyl 2-oxocyclopentanonecarboxylate, and N-methylindole has been studied experimentally by monitoring the temporal course of the reaction by (1)H NMR, kinetic isotope effect studies, and control experiments. DFT calculations have been carried out using a dispersion-corrected range-separated hybrid functional (ωB97X-D) to explore the basic elementary steps of the catalytic cycle. The experimental results indicate that the reaction proceeds v…

Cross-Dehydrogenative Couplings between Indoles and beta-Keto Esters: Ligand-Assisted Ligand Tautomerization and Dehydrogenation via a Proton-Assiste…

2014

Cross-dehydrogenative coupling reactions between β-ketoesters and electron-rich arenes, such as indoles, proceed with high regiochemical fidelity with a range of β-ketoesters and indoles. The mechanism of the reaction between a prototypical β-ketoester, ethyl 2-oxocyclopentanonecarboxylate, and N-methylindole has been studied experimentally by monitoring the temporal course of the reaction by (1)H NMR, kinetic isotope effect studies, and control experiments. DFT calculations have been carried out using a dispersion-corrected range-separated hybrid functional (ωB97X-D) to explore the basic elementary steps of the catalytic cycle. The experimental results indicate that the reaction proceeds v…

Selectivity in Propene Dehydrogenation on Pt and Pt3Sn Surfaces from First Principles

2013

Propene can be produced via dehydrogenation of propane on Pt-based catalysts; however, the catalysts are plagued by low selectivity toward propene and high coke formation. The selectivity can be improved and the coke formation reduced by alloying Pt with Sn. The alloying is known to weaken the binding of propene, which in part explains the improved performance. We conducted density functional theory calculations to study the dehydrogenation of propene on flat and stepped Pt and Pt3Sn surfaces. The steps on Pt dehydrogenate propene readily, whereas, on Pt3Sn, the steps are inert because they are decorated with Sn. Our results indicate that the high selectivity and low coking on the Pt–Sn cat…