Quantum Chemistry Research Of NO Heterogeneous Reduction Under O₂/CO₂Amosphere

Oxy-fuel combustion technology is considered as a clean coal combustion technologywith promising prospect. According latest research, the new combustion technology caneffectively reduce the NOxemission. The detailed reaction mechanism is still not quilt clearyet. Elemental reactions of NO heterogeneous reduction by char under Oxy-fuelcombustion were investigated in this paper.The geometry optimizations of reactants, transition states, intermediates and productsof the reactions were studied by using density functional theory （DFT）, B3LYP, at6-31G（d） basis function level. Based on the analysis of reaction pathways, molecule energies werecalculated by a higher level ab initio method, QCISD（T）/6-311G（d, p）, and corrected withzero point energy. The activation energies and the reaction rate constants were calculatedby transition state theory （TST）, and the Arrhenius formulas of each reaction were workedoutThe study of CO₂, O₂adsorption in coal surface was taken using the coal solid surfacemodel. Adsorption energy in coal surface was worked out. Heterogeneous mechanism ofNO and CO reaction in coal surface was studied by using density functional theory.Basedon the analysis of reaction pathways, molecule energies were calculated by ab initio method,B3PW91/6-31G（d）, and corrected with zero point energy. The activation energies and thereaction rate constants were calculated by transition state theory. Compare two reactionpath rate constants, we can found that due to the presence of CO, the process of NOreduction in the char surface was greatly accelerated. This reaction mechanism can wellexplain the important role of high concentration CO₂atmosphere in promoting the NOreduction process under O₂/CO₂atmosphere. The char-NO heterogeneous reductionmechanisms on Oxy-fuel combustion were investigated in this work, and the importantreaction pathways as well as kinetic parameters were analyzed, which provide a theoreticalbasis for the further study of char combustion mechanism under O₂/CO₂atmosphere.