Modeling of the Co-Mn-Br catalyzed liquid phase oxidation of p-xylene to terephthalic acid and m-xylene to isophthalic acid

The current kinetics of PX or MX oxidation in liquid phase failed to incorporate the effect of the proposition and concentration of Co-Mn-Br ternary catalyst, although they play a significant role in the oxidation rate and selectivity. In this work, based on the catalytic mechanism of hydrocarbon oxidation and collision theory, a three-parameter model containing the catalyst proposition and concentration was developed. The reliability of this model was confirmed by comparing experimental data at different catalyst concentrations and ratios. The parameters a and b are related to the reactivity of Co and Mn ions respectively, and they are transferrable between PX and MX oxidation. However, the parameter c is only related to the methyl reactivity of PX or MX with Br?. The predicted relative reactivity of PX to MX is close to the famous Hammett structure-reactivity relationship. (C) 2020 Elsevier Ltd. All rights reserved.