Kinetics of MnO₂-catalyzed acetic acid oxidation in supercritical water

Acetic acid was oxidized in supercritical water over a bulk MnO₂ catalyst. CO₂, the complete oxidation product, was produced almost quantitatively. The rate of acetic acid disappearance exhibited saturation kinetics with respect to acetic acid, a maximum with respect to the oxygen concentration, and an independence from the water concentration. We identified a global rate law that was both qualitatively and quantitatively consistent with these experimental results. Using this catalytic rate law and literature rate laws for noncatalytic oxidation of acetic acid in supercritical water, we found that the use of MnO₂ as an oxidation catalyst can reduce the reactor volume required for treatment of aqueous solutions of acetic acid by more than 2 orders of magnitude.