Catalytic Effect of Carbon Dioxide on Reaction OH + CO → H + CO 2 in Supercritical Environment: Master Equation Study

We investigated the reaction rates of OH + CO → H + CO 2 in supercritical CO 2 environment with and without additional CO 2 molecule included in reactive complex. Ab initio potential energy surfaces previously reported a lower activation barrier and hence a catalytic effect of additional CO 2 molecule. Here we solve the steady-state unimolecular master equations based on the Rice–Ramsperger–Kassel–Marcus theory (RRKM) and compare the rates for the two mechanisms. We found that the alternative reaction mechanism becomes faster at high pressure and low temperature, when the concentration of prereactive complex with additional CO 2 molecule becomes appreciable. Therefore, this catalytic effect may be important for the chemical processes in CO 2 solvent but is unlikely to play a role during combustion.