Kinetics of Acetic Acid Oxidation in Snpeicritical Water

Acetic acid was oxidized in supercritical water in batch microreactors at temperatures between 380 and 440 °C. The acetic acid concentrations ranged from 1.0 x 10^-4 to 5.2 x 10^-3 M, the oxygen concentrations ranged from 5.7 x 10^-3 to 7.1 x 10^-2 M, and the water density ranged from 6.7 to 25 M. Oxygen was always present in at least 3.5 times the stoichiometric amount required for complete oxidation. Analysis of the kinetics data showed that the global oxidation rate law was first order in acetic acid, 0.6 order in oxygen, and second order in water. The global rate constant has a pre-exponential factor of 10^19.8 M^-2.6 s^-1 and an activation energy of 73.6 kcal/mol. This rate law also satisfactorily describes other sets of experimental data in the literature for the oxidation of acetic acid in supercritical water.