Simultaneous Catalytic Reductions of NO and SO2 by H2 over Nickel-Tungsten Catalysts

The simultaneous reductions of SO 2 and NO by H 2 on sulfided nickel-tungsten catalysts are investigated for the first time . Virtually 100% conversions of NO and SO 2 with 100% and 90% selectivity toward nitrogen and sulfur, respectively, over sulfided NiW/Al 2 O 3 have been revealed at 550 °C. As a result, this highly active and selective catalyst has been characterized extensively by X-ray diffraction, X-ray photoelectron spectroscopy, and Raman spectroscopy. It has been found that the oxidative leakage of lattice sulfur by NO results in a rapid deactivation of this sulfided catalyst in both NO decomposition and the NO reduction reaction. The sulfur produced from the hydrogen reduction of SO 2 can, however, replenish the lost sulfur while maintaining the essential sulfide structure necessary for steady catalytic activity. Thus, a tentative reaction mechanism for the simultaneous reductions of SO 2 and NO with H 2 over this new sulfided NiW/Al 2 O 3 catalyst is proposed.