Diesel engine exhaust treatment with a pulsed streamer corona reactor equipped with reticulated vitreous carbon electrodes

Reticulated vitreous carbon (RVC) has recently been shown to be useful for high-voltage and ground electrodes in gas-phase pulsed streamer corona reac tors. RVC disks with large macroscopic porosity are placed perpendicular to the gas flow and the main axis of a cylindrical corona reactor This electr ode geometry produces streamers that propagate in the direction of the gas flow and are uniformly distributed in the cross section of the reactor. Thi s highly electrically conductive material has large macroscopic porosity, t hus allowing for gas flow through the electrodes with low pressure drop. Pr evious work has considered the effects of PVC electrodes on NO/NOx removal from various test gases containing air, water vapor, and ethylene, The pres ent studies show removal of NO/NOx from the exhaust of a 5-kW diesel engine . Under cold reactor operating conditions (12 degreesC) 81% NO and 53% NOx could be removed at an energy yield of 4.8 g/kWh (based on NO). Furthermore , experiments with the combination of TiO2 or gamma -Al2O3 catalyst particl es placed in the region between the high-voltage and ground electrode disks gave NO removal at energy yields of 29 g/kWh and 9 g/kWh, respectively, at about 100 degreesC, and significant fractions of the nitrogen were recover ed as NO3- deposited on the catalyst surface, The RVC electrode system with out catalysts was found to lead to efficient ozone production (55-70 glkWh) in dry air at room temperature.