Promotional effect of CuO loading on the catalytic activity and SO2 resistance of MnOx/TiO2 catalyst for simultaneous NO reduction and Hg0 oxidation

Abstract

CuO loaded MnOx/TiO2 mixed oxide (CuMnTi) synthesized by an ultrasonic-assisted impregnation method was for the first time employed for simultaneous nitrogen monoxide (NO) reduction and elemental mercury (Hg0) oxidation under selective catalytic reduction (SCR) atmosphere with the presence of NH3. The CuMnTi catalyst exhibited a wide temperature window from 150 to 250 °C for both NO reduction and Hg0 oxidation. At the optimal temperature of 175 °C, CuMnTi reduced 96.4% of the inlet NO and oxidized 100% of the inlet Hg0 at a very high gas hourly space velocity (GHSV) of 40,000 h−1. O2, HCl and NO significantly promoted Hg0 oxidation and offset the adverse effect of detrimental flue gas components such as water vapor, SO2 and NH3. The protection effect of CuO over MnOx reserved enough active sites of CuMnTi for Hg0 oxidation in the presence of NH3 or SO2. Compared with MnOx/TiO2 (MnTi), the superior redox property, enlarged Hg0 adsorption capacity and decent SO2 resistance of CuMnTi ternary system were evidenced to account for its improved catalytic activity. This study indicated future potential for applying CuMnTi catalyst in simultaneous NO reduction and Hg0 oxidation in low-temperature (150–250 °C) and low-rank (sub-bituminous and lignite) coal combustion flue gases.