Low pressure RF plasma reactions in light hydrocarbons: Methane

Abstract

The plasma decomposition of methane in an inductively coupled radiofrequency glow discharge was studied by using a static system at pressures of 0.25, 0.5 and 1 torr. The effect of input power (between 25 and 100W) and specific energy E s (up to 3×10 6 J/g) was investigated. The gaseous products were identified and measured by gas chromatography. The total pressure of the system increased with delivered energy, E s . The main products were H 2, C 2H 6, C 2H 2, C 3H 8, C 2H 4 (in decreasing order of importance). The concentration of H 2 increased with E s and reached a constant value depending on initial pressure and input power. During the initial stage of the discharge, the concentration of other gaseous products reached a maximum, and a regular decrease took place then, asimptotically approaching a small constant value, different from zero. The formation of unsaturated compounds increases with input power and by decreasing the initial pressure. The experimental results were compared with previously reported literature data obtained by M.S. analysis. The yield of polymer and its hydrogeń/carbon ratio were calculated and correlated with the variation of discharge parameter.