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

Selective catalytic reduction of NOx by hydrogen (H-2-SCR) in the presence of oxygen has received much attention as a potential technology for reducing NOx emissions. A lot of research has been done in order to understand the reaction mechanism of H-2-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 H-2 and O-2, water, sulfur, CO and CO2) on the catalytic performance of some H-2-SCR catalysts has been discussed. Finally, future research directions in the area of H-2-SCR have been proposed.