Decomposition of benzene as a tar analogue in CO2 and H2 carrier gases, using a non-thermal plasma

Abstract

Cracking of benzene in a non-thermal plasma (NTP) dielectric barrier discharge reactor (DBD) was investigated in CO2 and H2 carrier gases. Benzene was acting as an analogue for gasification tar, and CO2 and H2 are abundant in gasifier product gas. A parametric study in terms of specific input energy (SIE), residence time, concentration and temperature was performed to determine the optimal conditions for tar conversion. It was found that almost complete removal of benzene (36 g/Nm3) was observed in each carrier gas above 30 kJ/L and at 4.23 s. Lower hydrocarbons (<C6) (LHC) and solid residue were common products in both carrier gases. The selectivity to LHC in H2 carrier gas was higher (12%) than CO2 (2%) carrier gas, and CO was the major gaseous product in CO2 carrier gas. However, the problem of solid formation in the reactor was completely eradicated by operating at elevated temperatures in H2 carrier gas. The selectivity to lower hydrocarbons increased with increasing temperature. At 400 °C in H2 carrier gas, the selectivity to LHC reached 91% with no formation of solid residue. The major lower hydrocarbons at these conditions were CH4 (82%) and C2 (C2H6 + C2H4) 6.6%.