Density Functional Theory Study on the Effect of Sodium on the Adsorption of NO on a Char Surface

In order to clarify the effect of sodium on the heterogeneous adsorption of NO on a char surface, several reasonably simplified saturated and unsaturated char models were selected as research objects, and Na atoms were decorated on the char models. Each char model and NO adsorption product were optimized by using density functional theory at the GGA-PBE (generalized gradient approximation-Perdew-Burke-Ernzerhof) level to obtain the adsorption energy of NO on different models. The results indicate that the addition of Na atoms catalyzes the adsorption of NO molecules by an saturated char structure, the adsorption form is changed from physisorption to chemisorption, and the adsorption energy is increased from -15.6 to -98.2 kJ/mol. The adsorption energy of NO molecules with an unsaturated armchair-type char structure containing edge active sites is affected by sodium atoms, increasing from -211.7 to -303.6 kJ/mol, while the adsorption capacity of the zigzag-type char structure for NO molecules is hardly affected by Na atoms. This study provides a theoretical basis for the development of clean utilization technology of high-alkali coal.