Mn-TiO2 catalyst collaborates with trace O3 to enhance the removal of mercury in ESP environment

Abstract

Ozone, known for its strong oxidizing properties, is commonly utilized in water pollution control. However, the catalytic ozonation of gaseous pollutants also shows potential as an emission reduction technology. The challenge lies in the high concentrations of ozone required in the catalytic process, which increases costs and complexity, hindering widespread adoption. Industrial electrostatic precipitators (ESPs) powered by high-voltage sources can produce ozone during operation, potentially causing environmental pollution if not managed. This study suggests utilizing a catalyst in the low-concentration ozone environment generated by an ESP for the catalytic oxidation of Hg0 in flue gas. The removal efficiency of Hg0 by either the catalyst alone or ozone alone (O3: 10 ppm) is modest at 43 % and 8 % respectively. However, when combined, the catalyst and ozone demonstrate a remarkable removal efficiency of over 98 %, significantly outperforming their individual capabilities. Furthermore, this process exhibits consistent high efficiency in a wide temperature range of 50–150 ℃. The study reveals that in the absence of O3, adsorbed oxygen acts as the primary oxidant, limiting the oxidation of Hg0. The introduction of O3 enhances electron transfer within the Mn-Ti catalyst, optimizing the electronic structure of oxygen and enhancing the oxidizing capacity of lattice oxygen, resulting in superior Hg0 removal efficiency. These findings offer valuable insights for the catalytic ozonation of Hg0.