Reaction mechanism of plasma chemistry in CO2 hydrogenation: The effect of CO2/H2 ratio

CO₂ hydrogenation reaction was conducted in dielectric barrier discharge plasma at ambient condition. A comprehensive investigation was studied on the effect of the CO₂/H₂ molar ratio. The CO₂ conversion showed a decreasing trend with increasing CO₂/H₂ molar ratio, whereas CO₂ conversion rate exhibited an opposite tendency. The conversion of CO₂ was predominantly governed by vibrational excitations induced through electron collisions. The energy loss fractions for CO₂ reactions were identified as the primary contributor to energy consumption in higher CO₂/H₂ ratio range. This phenomenon can be attributed to increase in both E/N and electron energy corresponding to elevated CO₂/H₂ molar ratio. Furthermore, electron energy, E/N, and gas composition played crucial roles in the plasma chemistry for the CO₂ hydrogenation reaction. An increased concentration of CO₂ significantly enhanced both E/N and electron energy, thereby facilitating electron excitation reactions and subsequently elevating the CO₂ conversion rate.