Effect of precursors on the structure and activity of CuO-CoOx/γ-Al2O3 catalysts for NO reduction by CO

Abstract

Catalytic reduction of NO by CO was studied over a series of CuO-CoOx/γ-Al2O3 catalysts prepared by co-impregnation with different copper and cobalt precursors (acetate and nitrate) to evaluate the structure–activity relationship. The obtained samples were characterized in detail by means of XRD, LRS, XPS, H2-TPR and in situ FT-IR technologies. Results indicate that copper oxide is agglomerated while cobalt oxide is dispersed on γ-Al2O3 for the catalyst prepared from copper acetate and cobalt acetate precursors (CuACoA); CuxCo3-xO4 spinel is formed and agglomerated on the catalyst prepared from copper nitrate and cobalt nitrate precursors (CuNCoN); while both copper oxide and cobalt oxide could be homogeneously dispersed for the catalyst prepared from copper nitrate and cobalt acetate precursors (CuNCoA), which exhibits the best activity for NO reduction by CO. Probably the synergistic effect between dispersed copper oxide and cobalt oxide is propitious to the oxygen transfer, which could be the reason for its high activities. Finally, a possible reaction mechanism was tentatively proposed to explore the different catalytic performances in NO reduction by CO model reaction.