Reduction of NO over TiO2-supported Cu catalysts

Abstract

TiO₂-supported Cu catalyst pretreated with H₂ at 473 K exhibits higher activity for the conversion of NO at low temperatures than Cu on other supports. The NO is converted to N₂via N₂O as an intermediate. In the reaction at 303 K, NO is reduced to N₂O. For the reaction above 323 K, the conversion of N₂O to N₂ is accelerated. The samples were characterized by X-ray absorption near-edge structure (XANES), UV–VIS and EPR spectroscopies. Treatment of the sample with hydrogen at 473 K leads to formation of Cu metal particles and promotes the reduction of Ti ions. The extent of the reduction of TiO₂ supporting Cu is much higher than that of TiO₂ itself. NO has a role in the oxidation of both Cu and Ti ion, even at room temperature and H₂ reduces both ions. The active Cu-species is a CuO particle with a Cu metal core.