Co-regulation of dispersion, exposure and defect sites on CeO2 (111) surface for catalytic oxidation of Hg0

Abstract

The additional cost of Hg0 capture in coal-fired power plants has facilitated the demand for environmental pollutants mitigation material for Hg0 oxidation to Hg2+ for an ultra-low Hg emission technology. Herein, a suite of CeO2-based catalysts were investigated aiming at ultra-low gaseous Hg0 emission at coal-fired power stations. Gaseous elemental mercury is feasible to be catalytically oxidized to Hg2+. The co-regulated dispersion, exposure and defect sites on CeO2 (111) surface with 2 wt% Ce and 8 wt% Mo compositions on γ-Al2O3 was found to be the most promising catalyst demonstrating a high catalytic oxidation efficiency, a broad operating temperature range and a low activation energy. Specifically, it is shown that the oxidation of Hg0 on the Ce-based catalysts can be enhanced by the addition of Mo (up to 8 wt%) via promoting the CeO2 (111) surface dispersion and exposure. Moreover, insights into the Ce and Mo synergistic interactions showed that it facilitated the formation of defect-containing surface sites. Besides, the co-regulation of dispersion, exposure and defect sites on CeO2 (111) surface was further studied by DFT calculations. This study provides a feasible approach in optimization of CeO2-based catalysts for catalytic oxidation of Hg0 to achieve efficient removal of environmental pollutants.