Effects ofCO2/NO/SO2in flue gas on selenium adsorption on carbonaceous surface

Abstract

AbstractThe effects of different flue gas compositions (CO2, NO, and SO2) on selenium (Se) adsorption mechanism over carbonaceous surface (CS) were explored using density functional theory (DFT). Considering weak interaction in the adsorption process, B3LYP‐D3/6‐31G(d) was employed to conduct geometry optimization and frequency calculations, and B3LYP‐D3/6‐311+G(d, p) was used to obtain more accurate single point energy. Results show that when the Se atom was absorbed on CS, the adsorption energies were −588.86 kJ/mol and −646.56 kJ/mol, respectively. It suggests that the adsorption process between Se atom and CS belongs to chemical adsorption. CO2and NO have negative effect on Se adsorption on CS, while SO2can promote the adsorption capacity of CS for Se atom. In order to further explain how SO2enhances the adsorption capacity of CS for Se, the atomic dipole moment corrected Hirshfeld (ADCH) charges were calculated. Calculation results show that SO2enhanced the electronegativity of the active site, contributing to the Se adsorption. Mayer bond order and ADCH charge are reliable tools to analyze adsorption process. Calculation results reveal the influencing mechanism of different flue gas compositions on Se adsorption, which can lay the theoretical basis for the control of Se during coal combustion.