Reduction of nitrogen oxides from simulated exhaust gas by using plasma–catalytic process

Abstract

Removal of nitrogen oxides (NO x ) using a nonthermal plasma reactor (dielectric-packed bed reactor) combined with monolith V 2O 5/TiO 2 catalyst was investigated. The effect of initial NO x concentration, feed gas flow rate (space velocity), humidity, and reaction temperature on the removal of NO x was examined. The plasma reactor used can be energized by either ac or pulse voltage. An attempt was made to utilize the electrical ignition system of an internal combustion engine as a high-voltage pulse generator for the plasma reactor. When the plasma reactor was energized by the electrical ignition system, NO was readily oxidized to NO 2. Performance was as good as with ac energization. Increasing the fraction of NO 2 in NO x , which is the main role of the plasma reactor, largely enhanced the NO x removal efficiency. In the plasma–catalytic reactor, the increases in initial NO x concentration, space velocity (feed gas flow rate) and humidity lowered the NO x removal efficiency. However, the reaction temperature in the range up to 473 K did not significantly affect the NO x removal efficiency in the presence of plasma discharge.