Preparation of alumite support and preliminary activity investigation for NO removal in SCR-HC over alumite catalyst

Abstract

A novel metallic monolith support was prepared by anodization, HWT (hot water treatment) and calcination. A commercial aluminum plate was anodized to form porous alumina films in the outer surfaces of the aluminum plate. In contrast to the anhydrous and amorphous alumina formed after anodization, the alumina in the anodized film with HWT was boehmite. The calcination after HWT made the boehmite film lose its hydrate water and rearrange into γ-alumina. The HWT and calcination significantly enhanced the surface area of the support due to the formation of numerous micropores (radius <25 Å). These new micropores were superimposed on the original skeleton structure to make up a binary-pore structure. The activities of Cu-Mn-CeOx/Al2O3/Al and Pt/Al2O3/Al alumite catalysts for the SCR-HC of NO by propene were investigated under oxygen-rich conditions. At low temperatures, Pt/Al2O3/Al exhibited a higher activity for NOx removal than Cu-Mn-CeOx/Al2O3/Al. However, a higher temperature (>623 K) made the activity of Pt/Al2O3/Al inferior to that of Cu-Mn-CeOx/Al2O3/Al. In comparison with Pt/Al2O3/Al, Cu-Mn-CeOx/Al2O3/Al had a lower N2O selectivity throughout the whole temperature range. The addition of SO2 inhibited the activity of Pt/Al2O3/Al, and this activity decay was reversible. On the other hand, a dramatic promotional effect of SO2 on reducing NOk was observed over Cu-Mn-CeOx/Al2O3/Al, but this influence of SO2 on the activity was irreversible. © 2003 The Society of Chemical Engineers, Japan.