Реферат: Silver catalysts show a relatively high selectivity in the hydrogenation of alpha,​beta-​unsatd. aldehydes to produce unsatd. alcs., but many aspects of the reaction mechanism remain to be clarified. Hydrogen activation on silver-​based catalysts presents the first problem because on clean silver, in contrast to metals of the Pt group, dissocn. of H2 is a highly activated, endothermic process. On the basis of high-​level d. functional (DF) results for periodic slab models, we suggest oxygen impurities to be involved as active sites for hydrogen activation. Furthermore, with acrolein as representative reactant, we studied pathways for the hydrogenation of C=O and C=C bonds on clean silver and various types of oxygenated surfaces. While hydrogen dissocn. is favored on oxygen species, the hydrogenation reaction is likely to proceed on clean metal terraces. The calcd. energetics and activation barriers indicate similar rates for the prodn. of unsatd. alc., propenol, and satd. aldehyde, propanal. Indeed, a selectivity of up to 42​% for propenol was obtained exptl. on silica-​supported silver catalysts by P. Claus et. al. The different behavior of Ag and Pt catalysts (on the latter, mainly aldehydes are produced) is discussed by comparing our DF results to those of Sautet et. al. calcd. for Pt(111)​.

Библиографическая ссылка: Rösch N. , Mohammad A. , Lim K. , Yudanov I.V. , Neyman K.M.
Acrolein Hydrogenation on Silver Catalysts: A Density Functional Study of Mechanism
234th ACS National Meeting 19-23 Aug 2007