Formation and reaction of surface acetate on Al2O3 during NO reduction by C3H6

In situ IR spectra were recorded during the selective reduction of NO by C3 H6 on Al2O3 at 573 K, and strong bands due to the adsorbed acetate were obs erved, accompanying weak bands due to formate and nitrate. The acetate was also formed in C3H6+O-2, while nitrate was formed in NO+O-2. The reactivity of acetate with NB,species was examined by exposing it to He, NO, O-2 or N O+O-2 while monitoring its rate of disappearance, and the results showed th at the acetate reacts preferentially in NO+O-2. A complementary set of expe riments by GC showed that N-2, CO and CO2 are produced by the reaction of a cetate with NO+O-2. The results demonstrate that acetate and nitrate signif icantly contribute to the formation of N-2 during the present reaction. A p ossible reaction mechanism is proposed, which explains the role of O-2 in f acilitating the reduction of NO by C3H6. (C) 1998 Elsevier Science B.V. All rights reserved.