The Effect of Oxygen Played in Nitrous Oxide Heterogeneous Reduction and the Behavior of Oxygen on Char Surface: Quantum Chemical and Kinetics Calculations

Oxygen plays an important role in heterogeneous reduction of N2O by char in coal-fired power plants. In this study, we use quantum chemistry to investigate the most probable transition states, intermediates and products in the process of heterogeneous reduction between char and N2O and to study the behavior of oxygen remaining on the surface of char. The oxygen-containing char surface, both the armchair and zigzag char, are beneficial to the adsorption of N2O, but inhibits the reduction of N2O. The mechanism and reaction rate between N2O and two char models are different, which allowed us to study the different effects of oxygen on the heterogeneous reduction of N2O by two char models. The results show that the adsorption rate constant of N2O in the zigzag model is always greater than that of the armchair model and oxygen has a significant effect on the desorption of N-2 on the surface of armchair char. The behavior of oxygen remaining on char surface will take place CO2 desorption, and it markedly occurs when the rate constants are higher than 10 degrees s(-1) (>1000 K). The values of activation energy required for CO2 desorption and the temperature of desorption are all consistent with available experimental results