H2 dissociation over Ag/Al2O3: the first step in hydrogen assisted selective catalytic reduction of NOx

Abstract

Hydrogen assisted selective catalytic reduction of NO_x over Ag/Al₂O₃ with either hydrocarbons or ammonia as reducing agents is an emerging technology for lean NO_x reduction. Herein, we present a density functional theory study of H₂ dissociation over a representative set of sites present on the Ag/Al₂O₃ catalyst. Whereas H₂ dissociation over supported Ag ions and oxidized Ag surfaces is found to be facile, dissociation over metallic Ag, defect free Al₂O₃ and alumina-supported Ag is associated with high barriers. The results are rationalized by analysis of the electronic structure.