Simulation of toluene liquid-phase oxidation

Liquid-phase oxidation of toluene by air is an environmentally benign process to produce benzoic acid and benaldehyde. Based on the compositional analysis of the oxidation products and the experimental observations, a reasonable mechanism and reaction network were proposed, and a kinetic model was derived. The model well described the kinetics data which were obtained in a bubble column reactor under conditions close to commercial operations. Using this kinetic model, a commercial process of liquid-phase oxidation of toluene was simulated. The results showed that the reaction in the industrial reactor was limited by the feed amount of oxygen. Measures like increasing air flow rate, increasing both gas and liquid feed rates, or using oxygen-enriched air were proposed to enhance the oxidation reaction. Simulations revealed that such measures could significantly enhance the production. Using an enriched air with an oxygen mole ratio of 31.1%, the toluene conversion reached 22.24%. Increasing air flow by 1.59 times, the toluene conversion increased to 18.61% and the productivity increased to 1.31 times. If increasing both gas and liquid feed rates simultaneously, the productivity increased to 1.71 times.