The effect of Na/K on the NO adsorption behavior and heterogeneous reduction of internal nitrogen-containing char: A DFT study

Sodium and potassium in high alkali coal have an effect on the heterogeneous reduction of NO with char. The microscopic mechanisms of the effect of Na and K on the adsorption behavior and heterogeneous reduction roads of NO on the surface of internal nitrogen-containing char were investigated at the GGA-PBE level using DFT. The adsorption energy of NO on the surface of nitrogen-containing char doped with Na and K was calculated using zigzag, armchair and saturated structures, and the reaction path of Z-N-2 with NO was also calculated. The results showed that the adsorption effects of the three types of nitrogen-containing char on NO ranked from strong to weak were: Z-N > A-N > G-N. The addition of Na and K both promoted the adsorption of NO with char structure. The highest energy barrier for the reaction of the Z-N-2 structure with NO was 232.80 kJ/mol, which decreased to 180.52 kJ/mol when Na doped and 176.04 kJ/mol when K doped. The exotherm of the reaction increases from 378.59 to 1245.26 kJ/mol, it appears that the addition of sodium and potassium facilitates the reaction. The study will provide a theoretical pavement for the continued study of the heterogeneous reduction process, which is of great significance for the clean use of high alkali coals.