New trends in the rate behavior of rhodium-catalyzed carbonylation of methanol

The kinetics of the carbonylation of methanol to acetic acid using homogeneous rhodium complex catalysts was studied in aqueous and acetic acid media. In aqueous media, the rate was found to be dependent on carbon monoxide and methanol concentrations. The rate was 0.64th order with respect to methanol concentration. However, with respect to carbon monoxide concentration, the rate was first order at low partial pressures of CO and zero order at higher partial pressures. In acetic acid media, the rate showed a zero-order dependence with respect to methanol concentration, while the rate dependence with respect to carbon monoxide partial pressure was similar to that in aqueous medium. A rate equation is proposed.