Selective Catalytic Reduction of NO in Diesel Exhaust over Anodic Alumina Catalyst

Abstract

A series of Cu-Mn-Ce/Al2O3 anodic alumina catalysts synthesized using the multi-impregnation method were employed to investigate the selective reduction of NO with C3H6 in the presence of excess O2. The presence of Cu additive greatly promoted the low-temperature de-NOx activity. A moderate loading of copper gave the most promising NOx conversion. In contrast, no promotional effect on low-temperature de-NOx activity was found when Mn was added to the alumina support. Although the Mn-supported catalyst exhibited a higher activity for the oxidation of NO to NO2, the addition of Mn to the Cu-Ce/Al2O3 catalyst had no positive effect on NOx reduction, due to the wasteful consumption of propene. The de-NOx activity of the Cu-Ce/Al2O3 catalyst was maintained at a relatively high level, even in the presence of excess SO2 (500 ppm) and H2O (10 vol%). Furthermore, the presence of SO2 was observed to greatly promote NOx reduction at 723 K.