A Laboratory Study of Low-Temperature CO Removal from Mobile Exhaust Gas Using In-Plasma Catalysis

Abstract

The combination of nonthermal plasma (NTP) with catalytic methods has been shown to improve catalyst light-off temperature via reactions among plasma discharge products and by-products. Thus, NTP may improve selectivity, process, and removal efficiency. In this study, NTP was combined with a catalytic film of mixed metal oxides (ceria-zirconia-gamma alumina layer) in the discharge zone to investigate low-temperature CO removal. Three different reactors having identical geometries were used: a plasma reactor, a catalytic reactor, and a hybrid plasma-catalytic reactor. The CO removal efficiency of 36.5% was achieved using hybrid plasma-catalytic reactor at 80 °C with 860 J/lit. The temperature and flow rate were found to have significant impacts (P-value ≤ 0.05), which is unexpected due to the key role of hydroxyl and active radicals induced by plasma discharge. Calculated synergy factor of about 2 signals call for further study on the hybrid properties of catalytic efficiency and plasma physics for optimal CO removal.