Plasma assisted heterogeneous catalytic oxidation of carbon monoxide and unburned hydrocarbons: Laboratory-scale investigations

Abstract

The use of upstream plasma treatment and ozone injection for the amelioration of the performance of diesel oxidation catalysis was investigated. Experiments presented here were performed in preparation for full scale tests on diesel engines. A significant augmentation of the oxidation rate of carbon monoxide was observed when plasma was applied upstream of a diesel oxidation catalyst and was attributed to a heterogeneous reaction of ozone with carbon monoxide. This observation led to ozone injection being investigated as an alternative to the direct application of dielectric barrier discharge type plasma to the gas upstream of the diesel oxidation catalyst. Results are presented about the two modes of the combination of the non-thermal plasma with the catalyst when they were applied during the catalyst light off, and are compared in terms of pollutant removal and energy cost for carbon monoxide and hydrocarbons. Mechanisms for these effects are proposed and the performances of the two approaches are discussed.