Atmospheric Environmental Protection Department, National Institute for Resources and Environment, 16-3 Onogawa, Tsukuba, Ibaraki 305, Japan
Abstract:
Performances of Pt and Rh catalysts for the selective reduction of NO were investigated using various reducing agents under high gas hourly space velocity (GHSV). Higher activities were attained when olefins were used for both Pt and Rh catalysts, and when oxygen containing substances such as methyl tert.-butyl ether (MTBE) were used in the case of Rh catalysts. Selectivity toward N2 for the NO converted was from 7% to 38% for Pt catalysts and from 45% to 67% for Rh catalysts. A comparison of N2O decomposition rates on these catalysts has shown that gaseous N2O is not a principal intermediate in the pathway for N2 formation. The high selectivity toward N2 for Rh/Al2O3 at low GHSV conditions is attributed to an additional catalytic effect of A12O3, which can reduce NO2 with propylene at temperatures as low as 350°C.