Simultaneous reduction of SO2 and NO by H2 over sulfided NiW/Al2O3 catalyst I.: Decomposition and reduction of NO

To investigate the possibility of simultaneous catalytic elimination of sulfur dioxide and nitric oxide by hydrogen, the reactions of NO decomposition and reduction by H-2 were performed over sulfided NiW/Al2O3 catalyst, which was prepared by impregnation method and then presulfided with a gas mixture of 0.5% SO2 2.7% H-2-Ar balance. The results showed that NO was decomposed completely over the sulfided catalyst accompanied with the formation of SO2, which resulted from the oxidation of the catalyst lattice sulfur. This oxidation led to complete loss of lattice sulfur and deactivation of the catalyst. After addition of equivalent H2 to NO stream, O-ad produced by NO decomposition was consumed by H-2 and lattice sulfur competitively, which suppressed the oxidation of lattice sulfur to a certain extent. Furthermore, part of the oxidized lattice sulfur could return to lattice sulfur to decrease its loss after a series redox reactions. The catalyst could maintain high activity for the reduction of NO by H-2 for a long time compared with the NO decomposition.