Comparison of non-thermal plasma decomposition characteristics of organo-halide gases under oxidizing and reducing atmosphere

Halide gases used in various industrial processes significantly contribute to the greenhouse
effect owing to their high GWPs. In addition, the halide gases have high chemical stability and
thus remain in the atmosphere for a long period. Therefore, effective treatment techniques of
halide gases are required to achieve environmental protection. The present work is
concerned with the destruction of halide gases such as CF4, CHF3 and CHClF2 in a wire-intube
pulsed corona reactor. In details, the influence of coexisting gases of H2 and O2 on nonthermal
plasma (NTP) decomposition of CF4, CHF3 and CHClF2 was investigated. As a result,
decomposition ratios of CF4 and CHClF2 by NTP were found to be higher under H2-N2
atmosphere than under N2 atmosphere. By contrast, the decomposition ratio of CHF3 under
H2-N2 atmosphere was lower than that under N2 atmosphere. In the case of O2-N2
atmosphere, lower decomposition ratios of CF4, CHF3 and CHClF2 were obtained under O2-
N2 atmosphere than under N2 atmosphere. Additionally, CHClF2 decomposition by NTP in the
presence of O2 yielded the reaction products such as CCl2F2, COCl2, COF2 and CO2. Then,
as the O2 concentration increased, the formation of undesirable product of CCl2F2 decreased,
while the generation of CO2 increased.