Influence of preparation methods on selective catalytic reduction of nitric oxides by propene over silver–alumina catalyst

Ag–Al2O3 catalysts prepared by impregnation, co-precipitation and single sol–gel methods were used for selective catalytic reduction of NOx by propene in the presence of oxygen. Ag(5)–Al2O3(SG) catalyst was found to be the most active catalyst for selective reduction of NOx, especially the activity in the low-temperature range, which may be ascribed to synergistic effect of BET surface area, pore size distribution, Ag species dispersion, the valence and morphology of the Ag species of the catalyst. The conversion of NOx increased with the oxygen concentration in the low-temperature region, whereas the NOx conversion decreased with the oxygen concentration in the high-temperature region. The differences of oxygen concentration on the catalyst from the previous report on impregnation Ag/Al2O3 catalyst with 2 wt.% Ag loading were discussed in detail.