Kinetic Investigations of p-Xylene Oxidation to Terephthalic Acid with a Co/Mn/Br Catalyst in a Homogeneous Liquid Phase

Kinetic investigations of the liquid phase oxidation of p-xylene (pX) to terephthalic acid (TPA) with Co/Mn/Br catalyst were performed in a stirred 50 mL Parr reactor at 200 °C and 15 bar pressure under conditions wherein product precipitation is avoided. The oxidant (O2) was introduced by sparging into the liquid phase at constant gas-phase O2 partial pressure. Apparent kinetic rate constants, estimated by regressing experimental conversion data to a pseudo-first order lumped kinetic model, are at least an order of magnitude greater than those reported in the literature for similar catalytic reactions. We attribute this difference to the presence of gas–solid and liquid–solid mass transfer resistances in the previous studies wherein the TPA product precipitates as it forms, trapping intermediate products and slowing down their oxidation rates. Our results also indicate that it is not possible to completely eliminate the gas–liquid mass transfer limitations associated with the fast intermediate oxidation ...