Methane conversion with carbon dioxide in plasma-catalytic system

The hybrid plasma-catalytic system (HPCS) was used for the oxidative coupling of methane (OCM) with CO2. 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. Three kinds of packing were tested: Fe/Al2O3, NaY and Na-ZSM-5. The effects of both temperature (130–340°C) and gas flow rate on the conversion of methane and CO2 were studied. Hydrogen, carbon oxide, hydrocarbons C2–C4, and alcohols (methanol and ethanol) were identified in the outlet gas. Using the plasma +Fe/Al2O3 catalyst system led to obtaining hydrogen, carbon oxide, hydrocarbons and alcohols. The highest amount of methanol and ethanol was obtained in the system without packing and with a carrier (Al2O3). For the homogeneous system and the system with a carrier the increase of the residence time of gas in the reaction zone decreases the conversion of methane to methanol and ethanol. The conversion of methane to methanol at 240°C with Na-ZSM-5 was not observed. In the plasma – Na-ZSM-5 system, in the first hour of experiment, the aromatic hydrocarbons and a larger amount of iso-butane were observed in the outlet gas. After approximately 1h, liquid aromatic hydrocarbons in the gas mixture were not observed and the Na-ZSM-5 catalyst showed no change in selectivity in subsequent experiments. In HPCS with Na-ZSM-5 catalyst the amount of hydrocarbons, containing more than 4 carbon atoms was the highest. The overall methane conversion 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. [Display omitted] •The conversion of CH4 was conducted in a hybrid plasma-catalytic system.•Hydrogen, CO, hydrocarbons (C2–C4), and alcohols were found in the outlet gas.•With Na-ZSM-5 the CH4 conversion to C2–4 was higher than with others packings.•With Fe/Al2O3 the lowest amount of soot and non-volatile substances was observed. 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