Synergistic CO2 plasma catalysis: CO production pathways and effects of vibrationally excited species

Non-thermal plasmas provide a unique method of converting CO2 into CO and other fuels. However, how to improve the conversion rate and energy efficiency simultaneously still needs to be investigated. This paper proposes a novel plasma synergistic catalysis model developed by coupling the CO2 plasma and the reactions on the surface of Ni/gamma-Al2O3 catalysts. Our simulation results show that the conversion rate and energy efficiency are 32.3 % and 4.6 % under the plasma without catalysts, respectively. The direct electron impact dissociation consumes over 70 % energy cost of CO production and therefore is the key reason for the low energy efficiency. The plasma synergistic catalysis model suggests that Ni/gamma-Al2O3 catalysts can efficiently dissociate the vibrationally excited CO2v (especially high-level CO2v) molecules. The conversion rate and energy efficiency are increased to 39.2 % and 5.6 %, respectively. These results are in good agreement with the reported experimental and computational results, and indicate that improving the vibrational level of CO2v is a good way to improve the plasma catalytic efficiency. It is also shown that the effects of the CO2v vibrational level can be enhanced by increasing the pulsed power, repetition frequency, reducing the rising time, and controlling other process parameters.