5177-70-8Relevant academic research and scientific papers
Local reaction environments and their properties for ethene deuterogenation on the surfaces of SMSI catalysts
Yoshitake, Hideaki,Asakura, Kiyotaka,Iwasawa, Yasuhiro
, p. 4337 - 4346 (1988)
Ethene deuterogenation and H2-D2 exchange reaction over Nb2O5-supported Rh and Ir catalysts have been investigated in relation to strong metal-support interaction (SMSI) phenomena.The activation energies for these reactions were considerably changed by high-temperature reduction of the catalyst in the case of Ir/Nb2O5, but were not modified in the case of Rh/Nb2O5.The change is ascribed to a reduction in the energy barrier for deuterium dissociation.The deuterium distribution in ethane formed during ethene deuterogenation was also investigated at various reaction temperatures and as a function of the reduction time of the catalyst.By studying the catalysts in their working state instead of by static adsorption measurements two kinds of active sites in different environments are suggested to exist on the surface of these catalysts in the SMSI states.One of the sites (site I) is on the bare metal surface and the other (site II) is on the perimeter of a migrating NbOx island.The surface isotropic ratio of hydrogen during ethene deuterogenation is different at sites I and II.Site I, on which D2 dissociates, acts as a deuterium supply for site II.A model for the deuterogenation of ethene on the SMSI catalysts is proposed.
Hydrogenation of Ethylene over Platinum (111) Single-Crystal Surfaces
Zaera, F.,Somorjai, G. A.
, p. 2288 - 2293 (2007/10/02)
The hydrogenation of ethylene with both hydrogen and deuterium was studied(111) platinum single-crystal surfaces under a total pressure of 110 torr and a temperature range of 300-370 K.An activation energy (Ea) of 10.8 +/- 0.1 kcal/mol and kinetic orders with respect to hydrogen and ethylene partial pressure of 1.31 +/- 0.05 and -0.60 +/- 0.05, respectively, were observed.The deuterium atom distribution in the product from the reaction with D2 peaks at 1-2 deuterium atoms per ethane molecule produced, similar to what has been reported for supported catalysts.The reaction takes place on a partially ordered carbon covered surface, where the carbonaceous deposits have a morphology similar to that of ethylidyne.However, this ethylidine does not directly participate in the hydrogenation of ethylene, since both its hydrogenation and its deuterium exchange are much slower than the ethane production.A mechanism is proposed to explain the experimental results.
REACTIONS OF 2-METHYLPROPENE AND OTHER ALKENES ON ZINC OXIDE
Brown, Ronald,Kemball, Charles,Taylor, Duncan
, p. 2899 - 2914 (2007/10/02)
Studies have been made on the hydrogenation, deuteration and exchange with deuterium of ethene, propene and 2-methylpropene on zinc oxide and Arrhenius parameters for the reactions have been determined.Some general conclusions are reached about the catalytic behaviour of alkenes on zinc oxide from these and earlier results.Exchange occurs readily with alkenes which can dissociate to allyl intermediates but can also take place via the formation of vinyl intermediates with other alkenes, particularly at higher temperatures.Similar rates of alkane formation are found with different alkenes at temperatures at which the strengths of adsorption of the alkene are equivalent.The mechanism of alkane formation does not contribute to exchange of the alkene nor give rise to double-bond movement and the probable rate-determining step is the formation of adsorbed alkyl species which are then rapidly converted to alkane.
