Effect of Methane as an Additive in the Product Gas toward the Formation of Lower Hydrocarbons during the Decomposition of a Tar Analogue

Nonthermal plasma is being considered as an alternative technique to reduce gasification tars. In this study, a dielectric barrier discharge reactor was used to decompose toluene (tar representative) in a synthetic product gas (CH4, CO, CO2, and H-2). It was observed that the presence of methane in a model product gas significantly increased the selectivity of C-2 (C2H6 + C2H4) hydrocarbons when increasing the temperature up to 400 degrees C at constant power (40 W). The effect of specific input energy (SIE) (2.05-16.4 kW h/m(3)) and temperature (20-400 degrees C) was investigated. The conversion of a tar model compound (toluene) increased at higher SIE. Solid residues and lower hydrocarbons (LHC) formed at ambient temperature. Solid residues create operational problems, but here we observe that the effect can be substantially reduced by operating at high temperatures. Solid formation was significantly decreased at 400 degrees C and 40 W. Furthermore, the selectivity of LHC (C-2-C-6) increased to 77%. However, CH4 decomposition decreased at high temperature because of the formation of methane at elevated temperatures.