Numerical investigation on the heterogeneous pulsed dielectric barrier discharge plasma catalysis for CO2 hydrogenation at atmospheric pressure: Effects of Ni and Cu catalysts on the selectivity conversions to CH4 and CH3OH

The simulation model of the pulsed dielectric barrier discharge plasma catalytic CO2 hydrogenation is established to numerically investigate the effects of Ni and Cu catalysts on the selectivity conversions to CH4 and CH3OH. Under plasma without catalyst, the electron impact CO2 and CO produce CO and C, and then stepwise hydrogenations of CO and C generate CH3OH and CH4. Under plasma with Ni catalyst, Langmuir-Hinshelwood (LH) reactions mainly form the CHx(s) and Eley-Rideal (ER) reaction CH3(s) + H -> CH4 are the key paths of CH4 synthesis. Under plasma with Cu catalyst, the intermediate CH3O(s) is principally produced by the LH reaction between CH2O(s) and H(s), followed by the ER reaction CH2O(s) + H -> CH3O(s). While CH3OH(s) is mainly produced by the ER reaction CH3O(s) + H -> CH3OH(s), CH3O(s) + H(s) -> CH3OH(s) + S is a rate-limiting step owing to the higher reaction energy barrier.