Simultaneous catalytic oxidation mechanism of NO and Hg0 over single-atom iron catalyst

Among the many pollutants emitted from coal-fired power plants, elemental mercury (Hg0) and nitrogen oxides (NOx) are widely concerned and regarded as a global environmental problem. Catalytic oxidation is an effective method to remove the above power plant pollutants. Although the recent pioneering experiment found that single-atom catalysts (SACs) exhibit excellent performance for the oxidation of NO and Hg0, the reaction mechanism for the simultaneous removal of NO and Hg0 has not been thoroughly revealed. In this work, a singleatom iron catalyst supported by a double vacancy doped graphene substrate with four N atoms (Fe1N4) was used to explore the reaction mechanism of O2 simultaneous catalytic of NO and Hg0. By using DFT method and energy span model, all possible paths of simultaneous catalytic oxidation of NO and Hg0 are enumerated. Among the ten paths we found, Termolecular Eley-Rideal (TER) mechanism has the lowest energy barrier. The rate determining reaction barrier is 1.59 eV. Disregarding the contribution of molecular collisions, TER path is more kinetically favorable for the integrated removal of NO and Hg0. Comprehensive consideration of intermolecular collisions, the catalytic oxidation reaction follows the E-R mechanism. The study deepened the understanding of the reaction mechanism of simultaneous removal of NO and Hg0.

Automated summary

This study investigates the reaction mechanism of simultaneous catalytic oxidation of nitrogen oxides (NOx) and mercury (Hg0) using a new catalyst. Calculations and modeling reveal the mechanism with the lowest energy barrier and analyze the kinetics of this catalytic reaction. The study deepens our understanding of the reaction mechanism for the simultaneous removal of NOx and Hg0.