Conversion of dilute nitrous oxide (N2O) in N2 and N2-O2 mixtures by plasma and plasma-catalytic processesElectronic supplementary information (ESI) available. See DOI: 10.1039/c8ra05607b

A coaxial dielectric barrier discharge (DBD) reactor has been developed for plasma and plasma-catalytic conversion of dilute N 2 O in N 2 and N 2 -O 2 mixtures at both room and high temperature (300 °C). The effects of catalyst introduction, O 2 content and inlet N 2 O concentration on N 2 O conversion and the mechanism involved in the conversion of N 2 O have been investigated. The results show that N 2 O in N 2 could be effectively decomposed to N 2 and O 2 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 2 -O 2 atmosphere, however, N 2 O could be removed only at high temperature, producing not only N 2 and O 2 but also NO and NO 2 . Production and conversion of N 2 O occur simultaneously during the plasma and plasma-catalytic processing of N 2 O in a N 2 -O 2 mixture, with production and conversion being the dominant processes at room and high temperature, respectively. N 2 O conversion increases with the increase of discharge power and decreases with the increase of O 2 content. Increasing the inlet N 2 O concentration from 100 to 400 ppm decreases the conversion of N 2 O under an N 2 atmosphere but increases that under an N 2 -O 2 atmosphere. Concentrating N 2 O in the N 2 -O 2 mixture could alleviate the negative influence of O 2 by increasing the involvement of plasma reactive species ( e.g. , N 2 (A 3 Σ u + ) and O( 1 D)) in N 2 O conversion. Packing the discharge zone with a RuO 2 /Al 2 O 3 catalyst significantly enhances the conversion of N 2 O and improves the selectivity of N 2 O decomposition under an N 2 -O 2 atmosphere, revealing the synergy of plasma and catalyst in promoting N 2 O conversion, especially its decomposition to N 2 and O 2 . Production and conversion of N 2 O occur simultaneously, with production and conversion being dominant at room and high temperature, respectively.