High yield methane production from the hydrogenation of CO₂ using non-thermal plasma/catalysis

In this work, a dielectric barrier discharge (DBD) non-thermal plasma/catalytic reactor was used under a range of process conditions, designed to maximise the hydrogenation of CO₂ to methane. A Ni/Al₂O₃ catalyst was used in the plasma/catalysis reactor and the process parameters investigated were the effect of input plasma power, catalyst temperature, catalyst weight hourly space velocity (WHSV), and H₂/CO₂ ratio in relation to the methanation of CO₂. In addition, the effect of the catalyst active metal type (ruthenium, cobalt, and lanthanum) supported on Al₂O₃ under the optimum reaction conditions was investigated. The optimised system, using Ni/Al2O3, achieved a CO₂ conversion of 82.2 % with an energy efficiency of 22.5 gCO₂kWh−1, CH₄ selectivity of 90.2 % and energy efficiency of 7.4 gCH₄kWh−1 at the plasma input power of 70 W, catalyst temperature of 280 °C, catalyst WHSV of 768 ml/gcath, and H₂/CO₂ ratio of 4. The performance of the active catalyst metals in relation to CO₂ conversion to methane was Ru > Ni > Co > La.