Copper-impregnated Al–Ce-pillared clay for selective catalytic reduction of NO by C 3H 6

Abstract

The selective catalytic reduction (SCR) of NO by hydrocarbon is an efficient way to remove NO emission from lean-burn gasoline and diesel exhaust. In this paper, a thermally and hydrothermally stable Al–Ce-pillared clay (Al–Ce-PILC) was synthesized and then modified by SO 4 2−, whose surface area and average pore diameter calcined at 773 K were 161 m 2/g and 12.15 nm, respectively. Copper-impregnated Al–Ce-pillared clay catalyst (Cu/SO 4 2−/Al–Ce-PILC) was applied for the SCR of NO by C 3H 6 in the presence of oxygen. The catalyst 2 wt% Cu/SO 4 2−/Al–Ce-PILC showed good performance over a broad range of temperature, its maximum conversion of NO was 56% at 623 K and remained as high as 22% at 973 K. Furthermore, the presence of 10% water slightly decreased its activity, and this effect was reversible following the removal of water from the feed. Py-IR results showed SO 4 2− modification greatly enhanced the number and strength of Brönsted acidity on the surface of Cu/SO 4 2−/Al–Ce-PILC, which played a vital role in the improvement of NO conversion. TPR and XPS results indicated that both Cu + and isolated Cu 2+ species existed on the optimal catalyst, mainly Cu +, as Cu content increased to 5 wt%, another species CuO aggregates which facilitated the combustion of C 3H 6 were formed.