In situ DRIFTS study of surface species formed over sodium promoted Pt/Al2O3 catalysts during the reduction of NO by C3H6”

Summarization: The nature and the relative population of adsorbed species formed on the surface of un-promoted and sodium promoted Pt catalysts supported on γ-Al2O3 was investigated by using in situ DRIFT Spectroscopy, during the NO reduction by propene. Under steady-state reaction conditions, the surface of the un-promoted Pt/γ-Al2O3 catalyst is mainly covered by adsorbed hydrocarbon fragments, formates, acetates and cyanide species. In contrast, the surface of Na-promoted Pt(Na)/γ- Al2O3 catalysts is predominantly covered by NOx ad-species, carbonyls, cyanides and isocyanates, whereas no hydrocarbons fragments were detected under reaction conditions. The present results demonstrate that the strongly enhanced catalytic performance of Na-modified Pt(Na)/Al2O3 catalysts, can be attributed to the pronounced effect of alkalis on the hydrocarbon and NO chemisorption bonds, which in turn prevents self-poisoning of catalyst surface by strongly bonded hydrocarbon fragments and carboxylates.Παρουσιάστηκε στο: Protection and Restoration of the Environment I