465263 Study of Reactivity of CO+NO Reaction on Supported Pd Catalyst

Wednesday, November 16, 2016
Grand Ballroom B (Hilton San Francisco Union Square)
Yimeng Lyu, Uzoma Nwabara, Xiaoyin Chen and Johannes W. Schwank, Chemical Engineering, University of Michigan, Ann Arbor, MI

Palladium (Pd) is the primary component in most automotive three-way catalysts (TWCs). Under slightly lean conditions, CO in the exhaust emissions can be oxidized to CO2. The light-off of CO oxidation by O2 follows an S-shaped curve. Under stoichiometric conditions, where there is a lack of molecular O2 in the exhaust emissions, the conversion of CO to CO2 can be accomplished by the CO+NO reaction, where NO is reduced by CO to N2, to achieve the simultaneous removal of CO and NO. However, we found that when CO is oxidized by NO, instead of O2, the CO light-off curve has a concave shape. This phenomenon has been further investigated by comparing Al2O3 and Ce-Zr-O supported Pd catalysts with focus on the effects of different catalyst pre-treatment methods, catalyst aging, reactant feed (CO/NO) ratio, as well as the operating conditions such as heating and cooling on the reactivity of CO+NO reaction. DRIFTs experiments were carried out to study the CO+NO conversion to CO2+N2O, instead of the target products CO2+N2.

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