Recent advances in the selective catalytic reduction of NOx by hydrogen in the presence of oxygen

Abstract

Selective catalytic reduction of NO_x by hydrogen (H₂-SCR) in the presence of oxygen has received much attention as a potential technology for reducing NO_x emissions. A lot of research has been done in order to understand the reaction mechanism of H₂-SCR and some possible mechanisms have been proposed. These mechanisms can be classified into two categories: NO adsorption/dissociation mechanisms and oxidation–reduction mechanisms. Based on the discussion of the reaction mechanism, the influence of the nature of the noble metal, catalyst support, catalyst preparation method, promoters and reaction conditions (including the presence of H₂ and O₂, water, sulfur, CO and CO₂) on the catalytic performance of some H₂-SCR catalysts has been discussed. Finally, future research directions in the area of H₂-SCR have been proposed.