Comparative Plasma Chemical Reaction Studies of CH4/Ar and C2Hm/Ar (m = 2,4,6) Gas Mixtures in a Dielectric Barrier Discharge



Plasma chemical reactions in CH4/Ar and C2Hm/Ar (m = 2, 4, 6) gas mixtures in a dielectric barrier discharge at medium pressure (300 mbar) have been investigated. From mass spectrometry the production of H2 and formation of larger hydrocarbons such as CnHm with up to n = 12 is inferred. Hydrogen release is most pronounced for CH4 and C2H6 gas mixtures. Fourier Transform InfraRed (FTIR) spectroscopy reveals the formation of substituted alkane (sp3), alkene (sp2), and alkyne (sp) groups from the individual gases which are used in this work. Abundant formation of acetylene occurs from C2H4 and to a lesser extent from C2H6 and CH4 precursor gases. The main reaction pathway of acetylene leads to the formation of large molecules via C4H2 and, eventually, to nano-size particles. The experimental results are in reasonable agreement with simulations which predict a pronounced electron temperature and gas pressure dependency. (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)