Study of the Properties of CuO/VOx/Ti0.5Sn0.5O2 Catalysts and Their Activities in NO + CO Reaction

Abstract

CuO/VOx/Ti0.5Sn0.5O2 catalysts were prepared by an impregnation method and were tested on a NO + CO model reaction. Both copper oxide and vanadium oxide can be highly dispersed on Ti0.5Sn0.5O2 (denoted as TS, hereafter) support. The dispersed oxides form V−O−Cu species when coexisting in the catalyst system. The formation of V−O−Cu species renders the dispersed vanadium oxide aggregated and easier to be reduced; in contrast, the reduction temperature of dispersed copper oxide species is evidently higher than that without vanadium oxide (CuO/TS samples). The surface dispersed V−O−Cu species are mainly the active component for the NO + CO reaction. The activities of CuO/VOx/TS catalysts are highly dependent on the operating temperature and the amount of V−O−Cu species. In the reaction atmosphere, NO molecules are adsorbed onto Cu2+ sites, reduced Vx+ (V4+ or V3+) sites, and even TS support, forming −NO and NO3− species. Adsorption of CO molecules proceeds only on Cu+ sites. The active species change with varying reaction temperature; hence, the NO + CO reaction goes through different mechanisms at low and high temperatures over these catalysts.