Activity enhancement of bimetallic Co-In/Al2O3 catalyst for the selective reduction of NO by propene

Effect of additives In, Sn and Ag, on the catalytic performance of Co/Al2O3 catalyst prepared by sol–gel method for the selective reduction of NO with propene in the presence of oxygen was studied. Some catalysts were also characterized by N2-adsoption, X-ray diffraction (XRD), XPS and NO-temperature programmed desorption (TPD). Compared with Co/Al2O3 and In/Al2O3 catalysts, Co-In/Al2O3 catalyst showed higher activity in a wide range of reaction temperatures. The addition of SO2 to the feed significantly inhibited the NO reduction over Co/Al2O3 and In/Al2O3 catalysts, while Co-In/Al2O3 catalyst showed high activity. It still had better catalytic performance even in the co-presence of SO2 and H2O. Furthermore, it was found that Co-In/Al2O3 catalyst remained fairly active under high GHSV. The enhanced performance of Co-In/Al2O3 catalyst can be explained by the cooperative effect of Co species, indium oxide species and Al2O3 sites, which improved the conversion of NO to NO2 and facilitated the activation of propene, and NO2 was reduced by the activated propene over Al2O3 sites. The presence of oxygen contributes to the oxidation of NO and shows a promoting effect.