Nonthermal plasma-enhanced catalytic removal of nitrogen oxides over V2O5/TiO2 and Cr2O3/TiO2

A nonthermal plasma process (dielectric-packed bed reactor) was combined with catalyst to remove nitrogen oxides (NOx). Two different honeycomb catalysts such as V2O5/TiO2 and Cr2O3/TiO2 were compared with respect to the removal characteristic of NOx. The effect of oxygen content, water vapor, feed gas flow rate, reaction temperature, and initial concentration on the removal of NOx was examined. The plasma discharge was found to largely enhance the removal of NOx on the catalyst. Without plasma discharge, V2O5/TiO2 was superior to Cr2O3/TiO2 in terms of NOx removal activity. However, the degree of enhancement in NOx removal as a result of plasma discharge was similar for each system. Cr2O3/TiO2 catalyst reduced NO2 to both NO and N-2 while the reduction of NO2 back to NO was not significant on V2O5/TiO2 catalyst. The combined system of the nonthermal plasma with V2O5/TiO2 catalyst removed nearly 90% of NOx at 150 degreesC that is a relatively low temperature, compared to the typical temperature window of NOx reduction catalyst.