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

Plasma chemical reactions in CH4/Ar and C 2 H m /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 H 2 and formation of larger hydrocarbons such as C n H m with up to n = 12 is inferred. Hydrogen release is most pronounced for CH 4 and C 2 H 6 gas mixtures. Fourier Transform InfraRed (FTIR) spectroscopy reveals the formation of substituted alkane (sp 3 ), alkene (sp 2 ), and alkyne (sp) groups from the individual gases which are used in this work. Abundant formation of acetylene occurs from C 2 H 4 and to a lesser extent from C 2 H 6 and CH 4 precursor gases. The main reaction pathway of acetylene leads to the formation of large molecules via C 4 H 2 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)