Kinetics of the Reaction between CO2—CO and Liquid Copper

Direct determination of the rate of the reaction between CO₂—CO and pure liquid copper in the interfacial reaction regime and an examination of the effect of oxygen has been made by using the ¹⁴C isotope exchange technique. The first order rate constant for the dissociation of CO₂ on clean, oxygen-‘free’ surfaces is found to be described by the equation:

log K⁰(mol/cm².s.atm) = ? 3510/T ? 2.36

between 1150 and 1400°C, to within an uncertainty of +60%. The first order rate constant for the dissociation (k₂) and that for the formation (k₁) of CO₂ on oxygen-doped surfaces are related through the equation:

k1 = k²a⁰

where a_o the oxygen activity in liquid copper with the standard state defined by pCO₂Sol;pCO = 1. Full consistency is found between experiments with ¹⁴C-labelled C0₂ and CO. The effect of a₀ on the rate of dissociation of CO₂ is in agreement with the site-blocking model and the rate constant (k₂) is found to be consistent with the equation:

with a₀ between 0.015 and 50 at 1200°C. In comparison, the magnitude of the reaction rate is significantly greater than those suggested by earlier studies. Possible causes for the discrepancy are discussed.