Catalytic performance of Ag-Al2O3 catalyst for the selective catalytic reduction of NO by higher hydrocarbons

Silver-aluminum mixed oxide catalyst (Ag-Al2O3) prepared by the sol-gel met hod was studied for the selective reduction of NO by various alkanes in the presence of water vapor. As the carbon number of alkanes increases, the de -NOx activity and water tolerance were markedly increased. In the case of n -octane as a reductant, the presence of water vapor markedly promoted NO re duction. The results of reaction studies and in situ IR experiment showed t hat the possible reasons for the promoting effect by water vapor are the in hibition of the n-octane oxidation by O-2 and the suppression of the poison ing effect caused by carboxylate and carbonate species. Among various alumi na-supported transition metal catalysts, Ag-Al2O3 showed the highest activi ty for SCR by n-octane. Ag-Al2O3 showed higher NO conversion to N-2 and sel ectivity than alumina-supported Pt and Cu-ZSM-5 catalysts for the selective reduction of NO by n-octane and i-octane. (C) 2000 Elsevier Science B.V. A ll rights reserved.