A quantum chemistry study of heterogeneous reduction mechanisms of NO on the surface of char during pulverized coal reburning

作者：Zhang Xiu Xia; Zhou Zhi Jun^*; Zhou Jun Hu; Liu Jian Zhong; Cen Ke Fa

来源：Journal of Combustion Science and Technology, 2011, 17(2): 155-159.

• Arrhenius expressions
• B3LYP/6-31G
• Char
• Density functional theory (DFT)
• Density functional theory calculations
• Different mechanisms
• Heterogeneous reactions
• Heterogeneous reduction
• Intermediate reactions
• NO molecule
• Overall reactions
• Pulverized coal reburning
• Rate determining step
• Reaction pathways
• Single-point energy
• Stable species
• Surface nitrogen
• Transition state geometry
• Transition state theories

Density functional theory calculations were carried out to investigate heterogeneous reduction mechanisms of NO on the surface of char by using a simplified char model with armchair configuration. Both intermediate stable species and transition state geometries were optimized at B3LYP/3-21G*calculation level, and their single-point energies were calculated at B3LYP/6-31G(d) level. Two different reaction pathways were obtained for heterogeneous reactions between NO molecules and char model with armchair configuration, which corresponded to the two different mechanisms proposed. The highest energy barriers were 128.8 kJ/mol for the reaction of surface nitrogen species with one NO molecule, and 141.1 kJ/mol for the recombination of two surface nitrogen species. The overall reactions are exothermic reactions, which are in agreement with the experiment results. Rate constants for intermediate reactions were calculated by transition state theory and fitted to 2-parameter Arrhenius expressions. The rate constants of rate-determining steps for pathway 1 and pathway 2 are 6.12×109and 1.50×1011at 1473 K respectively.

• 出版日期2011
• 单位浙江大学