Modeling of the Solvent-Free Selective Oxidation of O-Xylene to O-Toluic Acid under Various Mass Transfer Conditions

O-Toluic acid (O-TA) serves as a crucial raw material in the synthesis of pesticides, pharmaceuticals, and various organic chemical products. Limited in-depth research has been conducted on the development of a kinetic model for the oxidation of OX to O-TA. In this work, a novel reaction pathway for this process was developed, without the use of acetic acid as a solvent, achieving a high yield and selectivity of O-TA (38.97 and 85.05%, respectively). A kinetic model that incorporates oxygen concentration and mass transfer effects was established to describe the oxidation behavior of OX accurately. The validity of the model was further confirmed through semicontinuous experiments conducted in a stirred-tank reactor (STR), demonstrating its ability to predict concentration variations under complex mass transfer conditions (ρ2 is 0.998, F-value is 1.46 × 106). This work offers new insights into the kinetic modeling of liquid-phase aromatic oxidation processes under challenging reaction conditions.