DFT Study on the C–NO Coupling Reaction with Different Active Sites

Abstract

ABSTRACT The heterogeneous interaction between NO and char with two to four active sites (R1–R3) has been studied using density functional theory (DFT). The thermodynamic parameters which can be used as an important foundation for distinguishing the differences in reaction mechanism are calculated. The calculations show that active sites play an important role in NO adsorption. R3 provides more sites for NO adsorption, which is more favorable for NO chemisorption. The energy barrier for NO reduction to N2O or N2 on R1, R2, and R3 surface is 122.25, 81.5, and 38.4 kJ/mol, respectively, signifying that the more active sites on char surface are more conducive to NO reduction. On the other hand, the difference in energy barrier values of N2 desorption on R2 and R3 surface reveal that oxygen-containing groups on different char surface have different effects on N2 desorption. Thermodynamic parameters of char-NO reaction at different active sites are further analyzed, and the strong dependence of the reaction process on the active sites is clarified through thermodynamics. The calculation results deepen the mechanism of NO reduction and lay a foundation for further research.