Kinetics of CO2 formation from the oxidation of phenols in supercritical water

Global power-law rate expressions were determined for the formation of carbon dioxide during the near critical and supercritical water oxidation of aqueous solutions of phenol and 2-chlorophenol in a plug-flow reactor at 300-420C and 185-278 atm. The phenolic compound was always the limiting reactant and the excess oxygen was between 180 and 1360 per cent. The kinetics of carbon dioxide formation and activation energies were determined. The rate of carbon dioxide formation was not dependent on the water concentration for either compound. The activation energies were low, suggesting that the major pathways leading to carbon dioxide did not include carbon monoxide or acetic acid as refractory intermediates. Yields of carbon dioxide from the oxidation of phenol and 2-chlorophenol were always less than the conversion of the corresponding phenol. Products of incomplete oxidation were present.