Transition metal-aluminate catalysts for NO reduction by C3H6

Transition metal-aluminum mixed oxide catalysts (Cu, Ni and Co-Al2O3), with spinel-type structure, were prepared by coprecipitation method. These catalysts showed high activity and selectivity for the selective reduction of NO by C3H6 in excess oxygen, and showed moderate activity even in the presence of 10% water. Among the catalysts tested, Cu-Al2O3 with 16 wt.% Cu content exhibited the highest activity at low temperature, though a bend over of NO conversion was significant at high level of O-2 concentration. At low level of O-2 concentration, Cu-Al2O3 exhibited higher activity than Cu-ZSM-5 below 623 K. In addition, Cu-Al2O3 showed higher hydrothermal stability than Cu-ZSM-5. The high activity and selectivity of M-Al2O3 were attributed to the surface aluminate phase, containing highly dispersed transition metal cations in Al2O3 matrix. (C) 1998 Elsevier Science B.V. All rights reserved.