Dielectric Barrier Discharge Processing of trans-CF3CH=CHF and CF3C(O)CF(CF3)2, Their Mixtures with Air, N2, CO2 and Analysis of Their Decomposition Products

Abstract

The experimental study of the degradation of gaseous dielectrics after processing in the dielectric barrier discharge (DBD) is presented. Two pure gases trans-CF3CH=CHF (HFO-1234ze(E)), perfluoroketone CF3C(O)CF(CF3)2 (C5K), and also the following mixtures 75 %HFO-1234ze(E):25 %N2, 12 %C5K:88 %N2, 18.5 %C5K:81.5 %dry air, 9 %C5K:57.5 %HFO-1234ze(E):33.5 %N2, 9 %C5K:56 %HFO-1234ze(E):35 %CO2 have been used as test-gases. A content of the decomposition products of the gases before and after a 5-h workout in the barrier discharge has been determined by means of the chromatography-mass spectrometry and gas chromatography methods. Dilution of C5K with dry air greatly increases the degree of conversion of the source gas in the barrier discharge. Dilution of HFO-1234ze(E) and C5K with nitrogen, and the use of ternary mixtures 9 %C5K:57.5 %HFO-1234ze(E):33.5 %N2 and 9 %C5K:56 %HFO-1234ze(E):35 %CO2 significantly reduces the degree of conversion of the mixture compared with the source gases in the barrier discharge. After the DBD processing of two test-gases a large quantity of toxic C3F6 was found in pure C5K, and also a large number of highly toxic CF3CCH was found in pure HFO-1234ze(E). The least amount of toxic products after the DBD processing was detected in mixtures HFO-1234ze(E):N2 and C5K:HFO-1234ze(E):N2. The mixture C5K:HFO-1234ze(E):N2 has the best features among studied mixtures.