The catalytic activity of CuO_x/ZrO_2 for the abatement of NO with propene or ammonia in the presence of O_2

摘要

Samples CuO_x/ZrO_2 (0.1-8.4 Cu atoms nm~(-2)) were prepared by adsorption or impregnation methods. The characterisation of samples by means of XPS, XRD, DRS, ESR, IR and volumetric adsorption of CO, showed copper dispersion up to 2.5 atoms nm~(-2), and the presence of CuO in samples with higher Cu content. The selective catalytic reduction of NO with propene or ammonia in the presence of excess oxygen, was studied in a flow apparatus with reactant mixtures of various composition (NO:C_3H_6:O_2=0-4000 ppm:100-2000 ppm: 0-3.5%; and NO:NH_3:O_2=0-700 ppm:700 ppm:3.6%). With both propene and ammonia, CuO_x/ZrO_2 catalysts containing up to 2.5 Cu atoms nm~(-2) were active, selective and stable as a function of the time on stream. On all catalysts, with ammonia as reducing agents, up to 523 K, NO conversion equalled NH_3 conversion leading to 100% selectivity. With both propene and ammonia, NO molecules that were converted to N_2 per Cu atom and per second were nearly independent of the Cu content up to 2.5 Cu atoms nm~(-2)