SELECTIVE CATALYTIC REDUCTION OF NITRIC-OXIDE BY N-DECANE ON CU SULFATED-ZIRCONIA CATALYSTS IN OXYGEN-RICH ATMOSPHERE/

The effect of sulfur and copper contents on the activity of Cu/sulfate d-zirconia (SZ) catalysts, in the selective reduction of NO by n-decan e, were investigated in the 298-723 K temperature range. ZrO2 and SZ s olids exhibited no activity below 773 K, Cu/ZrO2 is active and selecti ve at low temperature (<600 K) but oxidises selectively NO to NO2 at h igher temperatures. By contrast, whatever the temperature, a 100% sele ctivity to N-2 is obtained with Cu/SZ catalysts. The highest activity is reached with the catalyst containing the highest number of acid sit es which corresponds to a sulfur content close to the amount required to form a sulfate monolayer. Acidity plays a significant role only at temperatures above 600 K, where it is concluded that a bifunctional me chanism governs the reduction of NO to N-2. (C) 1998 academic Press.