Theoretical research on heterogeneous reduction of N2O by char

In order to investigate heterogeneous reduction of N2O by char, quantum chemistry theoretical calculation based on zigzag and armchair char edge model was conducted. Thermodynamics and kinetics calculation were carried out combined with density functional theory (DFT) and conventional transition state theory (TST). Theoretical calculation results indicate that heterogeneous reduction of N2O by char undergoes two stages: N2O decomposition on char edge and residual oxygen desorption from char edge. N2O decomposition process is an exothermic reaction and takes place spontaneously and irreversibly. Char acts as an important catalyst which not only provides free sites for the heterogeneous reduction but also reduces the reaction energy barrier. The participation of CO can significantly reduce reaction activation energy of residual oxygen desorption. The char edge structure has notable influence on activation energy of N2O decomposition on char edge. Activation energy values of N2O decomposition on zigzag and armchair char edge are 33.91 kJ/mol and 163.58 kj/mol, respectively. The calculation results can not only deepen understanding of the reaction mechanism but also provide theoretical guidance for operation optimization of low N2O emission. (C) 2017 Elsevier Ltd. All rights reserved.