Unraveling Temperature-Dependent Plasma-Catalyzed CO₂ Hydrogenation

Hydrogenation of carbon dioxide to value-added chemicals and fuels has recently gained increasing attention as a promising route for utilizing carbon dioxide to achieve a sustainable society. In this study, we investigated the hydrogenation of CO₂ over M/SiO₂ and M/Al₂O₃ (M = Co, Ni) catalysts in a dielectric barrier discharge system at different temperatures. We compared three different reaction modes: plasma alone, thermal catalysis, and plasma catalysis. The coupling of catalysts with plasma demonstrated synergy at different reaction temperatures, surpassing the thermal catalysis and plasma alone modes. The highest CO₂ conversions under plasma-catalytic conditions at reaction temperatures of 350 and 500 °C were achieved with a Co/SiO₂ catalyst (66%) and a Ni/Al₂O₃ catalyst (68%), respectively. Extensive characterizations were used to analyze the physiochemical characteristics of the catalysts. The results show that plasma power was more efficient than heating power at the same temperature for the CO₂ hydrogenation. This demonstrates that the performance of CO₂ hydrogenation can be significantly improved in the presence of plasma at lower temperatures.