Methane conversion with carbon dioxide in plasma-catalytic system

Abstract

The hybrid plasma-catalytic system (HPCS) was used for the conversion of methane with CO2 to higher hydrocarbons and alcohols. The investigation was carried out at the pressure of 1.2bar. A dielectric barrier discharge (DBD) reactor was powered at the frequency of about 6kHz. Molar ratio [CO2]:[CH4] in the inlet gas mixtures (CH4+CO2+Ar) was 1. The investigation was carried out for specific energy 1000–3500kJ/mol CH4. Three kinds of packing were tested: Fe/Al2O3, NaY and Na-ZSM-5. Ethane was the main component among the organic products. In the HPCS with Na-ZSM-5, in the first hour the formation of liquid products was observed.In HPCS with Na-ZSM-5 catalyst the amount of hydrocarbons, containing more than 4 carbon atoms was the highest. The overall methane conversion in HPCS with Na-ZSM-5 was 47.5% and 65% and the methane conversion to C2–C4 hydrocarbons reached 19.5% and 14.5% for gas flow rate 2 and 1Nl/h respectively.The highest share of hydrogen in H2 and C2–4 hydrocarbons was obtained in a homogeneous system. It was 75–92%. The highest methane conversion to alcohols (methanol and ethanol) was obtained in the homogeneous system and with Al2O3 it was 4.4% and 2.5% respectively. The increase of the residence time of gas in the reaction zone decreases the conversion of methane to methanol and ethanol in homogenous and with Al2O3.The temperature did not affect the methane conversion of methane to C2–C4 hydrocarbons in HPCS with Fe/Al2O3 and NaY. With Na-ZSM-5 conversion of methane to C3 and C4 at 340°C was 3 and 5times higher than that at 130°C respectively.