Formation of fluorine for abating sulfur hexafluoride in an atmospheric-pressure plasma environment

摘要

In this study, a large amount of toxic and reactive fluorine (F_2) was produced in the atmospheric-pressure microwave discharge environment by adding additives to abate sulfur hexafluoride (SF_6). When H_2 was added, the selectivity of F_2 was as high as 89.7% at inlet H_2/SF_6 molar ratio (R_(H_2)) = 1. Moreover, the conversion of SF_6, significantly increased from 33.7% (without additive) to 97.7% (R_(H_2) = 5) at [SF_6]= 1%, and 0.8 kW because the addition of H_2 inhibited the recombination of SF_6. With the addition of O_2, H_2 +O_2 or H_2O, the selectivity of F_2 was still greater than 81.2%, though toxic byproducts, including SO_2F_2, SOF_2, SOF_4, SO_2, NO, and HF, were detected. From optical emission spectra, SF_2 was identified, revealing the SF_6 dissociation process might be carried out rapidly through an electron impaction reaction: SF_6 → SF_2 +4F. Subsequently, F_2 was formed via the recombination of F atoms.