Nature of molecular hydrogen adsorbed on zinc oxide

Abstract

Publication costs assisted by the Petroleum Research FundThe reversibly adsorbed hydrogen and deuterium on zinc oxide at -195 and -183°( type III) has been examined by adsorption and ir techniques. The isotherms show a significant isotope effect and yield isosteric heats at low coverage of 2.2-2.5 kcal. Infrared studies and the temperature and pressure dependence show this hydrogen is present in molecular form and is limited to 5 to 10% of the surface. Poisoning studies with water suggest it occurs on the same sites as the dissociative type I hydrogen. Interpretation of the spectral results and the isotope effect suggest that there is a considerable barrier to rotation on the surface. The possible role of such a species in the ortho-para hydrogen conversion is discussed.

The surface chemistry of ZnO nanoparticles applied as heterogeneous catalysts in methanol synthesis

“…The hydrogen atoms were assumed to be bridge-bound between neighboring oxygen and zinc atoms. Molecularly adsorbed hydrogen is present on ZnO only at low temperatures (90 K) (type III) [66,67]. When CO was offered additionally to hydrogen, both bands of type I hydrogen adsorption, that is, m OH and m ZnH , were found to be shifted.…”

Nature and Estimation of Functional Groups on Solid Surfaces

“…Toluene is slowly chemisorbed on dehydroxylated zint oxide, giving rise to O-H and Zn-CH 2 Ph groups [794]. Hydroxyl groups are also formed in the irreversible adsorption of acetylene on zinc oxide [210,795]. This is also the case, when the surface is contacted with propene.…”

“…Ethylene is weakly adsorbed by n-bonding to surface sites [210,798]. Studies of the adsorption of propyne (methylacetylene) indicated that the reaction is analogous to that of propene, and that the adsorbed species is in equilibrium with the allene anion [210,795,799] 9CH2 -C=CH ~CH2=C=CH9…”

A DRIFT spectroscopic study of acetylene adsorbed on metal oxides

“…[9][10][11][12] However, the scarce data on adsorption of acetylene derivatives were presented for the oxides. Only data on the properties of the basic sites of alumina, [13][14][15] zinc oxide, 16,17 and also modified MgO systems [18][19][20] were published.…”