Promotional effect of CuO loading on the catalytic activity and SO₂resistance of MnO_x/TiO₂catalyst for simultaneous NO reduction and Hg⁰oxidation

CuO loaded MnO _x/TiO ₂ 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 (Hg ⁰) oxidation under selective catalytic reduction (SCR) atmosphere with the presence of NH ₃. The CuMnTi catalyst exhibited a wide temperature window from 150 to 250 °C for both NO reduction and Hg ⁰ oxidation. At the optimal temperature of 175 °C, CuMnTi reduced 96.4% of the inlet NO and oxidized 100% of the inlet Hg ⁰ at a very high gas hourly space velocity (GHSV) of 40,000 h ⁻¹. O ₂, HCl and NO significantly promoted Hg ⁰ oxidation and offset the adverse effect of detrimental flue gas components such as water vapor, SO ₂ and NH ₃. The protection effect of CuO over MnO _x reserved enough active sites of CuMnTi for Hg ⁰ oxidation in the presence of NH ₃ or SO ₂. Compared with MnO _x/TiO ₂ (MnTi), the superior redox property, enlarged Hg ⁰ adsorption capacity and decent SO ₂ 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 Hg ⁰ oxidation in low-temperature (150–250 °C) and low-rank (sub-bituminous and lignite) coal combustion flue gases.