Detailed Mechanism for Reduction of N2O over Rhodium by CO in Automotive Exhaust

作者：Su, Qingyun^*; Li, Yanbin; Wang, Sheng; Gao, Changming

来源：Topics in Catalysis, 2013, 56(1-8): 345-351.

DOI：10.1007/s11244-013-9978-4

• Automotive exhaust
• Nitrous oxide
• Carbon monoxide
• Rhodium
• Detailed mechanism
• Sensitivity analysis

Elementary-steps based mechanisms of CO-O-2 and CO-N2O over rhodium catalyst were proposed and utilized to simulate experimental data from literature. The results showed that the mechanisms possess good prediction capability. It was found that the dissociation of adsorbed N2O is the rate limiting step of N2O reduction under conditions characterized by high CO coverages. The rather high light-off temperature (50 % conversion) of CO-N2O (638 K) compared to that of CO-O-2 (453 K) is explained by the high temperature to initiate N2O dissociation to offer surface oxygen needed for CO oxidation. Removing CO out of the reaction system, the oxygen generated via the dissociation of adsorbed N2O accumulates on the surface of Rh, and finally leads to a poisoned catalyst and termination of the N2O reduction process. However, increasing the inlet CO concentration inhibits the adsorption of N2O to some extent, thus the reduction rate of N2O is lowered on the contrary. Analysis of kinetic parameters showed that facilitating CO desorption or the decomposition of adsorbed N2O leads to higher conversion of N2O, with the latter having larger influence.

• 出版日期2013-5
• 单位大连理工大学