Conversion of dilute nitrous oxide (NO) in N and N-O mixtures by plasma and plasma-catalytic processes.

A coaxial dielectric barrier discharge (DBD) reactor has been developed for plasma and plasma-catalytic conversion of dilute NO in N and N-O mixtures at both room and high temperature (300 °C). The effects of catalyst introduction, O content and inlet NO concentration on NO conversion and the mechanism involved in the conversion of NO have been investigated. The results show that NO in N could be effectively decomposed to N and O by plasma and plasma-catalytic processes at both room and high temperature, with much higher decomposition efficiency at 300 °C than at room temperature for the same discharge power. Under an N-O atmosphere, however, NO could be removed only at high temperature, producing not only N and O but also NO and NO. Production and conversion of NO occur simultaneously during the plasma and plasma-catalytic processing of NO in a N-O mixture, with production and conversion being the dominant processes at room and high temperature, respectively. NO conversion increases with the increase of discharge power and decreases with the increase of O content. Increasing the inlet NO concentration from 100 to 400 ppm decreases the conversion of NO under an N atmosphere but increases that under an N-O atmosphere. Concentrating NO in the N-O mixture could alleviate the negative influence of O by increasing the involvement of plasma reactive species (, N(AΣ ) and O(D)) in NO conversion. Packing the discharge zone with a RuO/AlO catalyst significantly enhances the conversion of NO and improves the selectivity of NO decomposition under an N-O atmosphere, revealing the synergy of plasma and catalyst in promoting NO conversion, especially its decomposition to N and O.