Bifunctional Mn-Cu-CeOx/γ-Al2O3 catalysts for low-temperature simultaneous removal of NOx and CO

Abstract

Nitrogen oxides (NOx) and carbon monoxide (CO) coexist in many industrial exhaust gases. The key to achieve selective catalytic reduction (SCR) of NOx by NH3 and catalytic oxidation of CO simultaneously is the desire to search for an efficient bifunctional catalyst. Herein, we developed MnCuCeOx/γ-Al2O3 catalysts with dual-active-sites through MnOx modification for simultaneous removal of NOx and CO. Mn(9)CuCeOx/γ-Al2O3 catalyst exhibited the optimal low-temperature activity, achieving 98% NOx conversion and 96% CO conversion at 200 ℃ with a gas hourly space velocity of 25000 h−1. The characterization results show that the strong interactions among manganese, copper and cerium oxides lead to well dispersed metal oxides with smaller particle size on the surface of Al2O3 support and generate abundant coordinated unsaturated ions (e.g., Mn3+ and Ce3+). These structural and chemical effects further enhance the low-temperature reducibility, the concentration of acid sites, the mobility of oxygen species, and the adsorption capacity for NO and CO of catalysts, leading to the excellent low-temperature activity. Moreover, dual-active-sites (i.e., separated SCR and CO oxidation active sites) are formed on the Mn(9)CuCeOx/γ-Al2O3 catalyst, which reduce the negative interaction between NH3-SCR and CO oxidation and enhance the simultaneous removal of NOx and CO. This work provides a novel idea for simultaneous abatement of NOx and CO emitted from industrial flue gas.