Solvent-free oxidation of p-tert-butyl toluene catalyzed with cobalt 4-tert-butylbenzoate in an internal circulation bubbling bed reactor

P-tert-butyl benzoic acid (PTBA) was synthesized by solvent-free oxidation of p-tert-butyl toluene (PTBT) at atmospheric pressure using cobalt 4-tert-butylbenzoate as catalyst and oxygen as an oxidant in a self-made internal circulation bubbling bed reactor (ICBBR). The effects of different catalysts and reactors on the reaction were investigated. The results show that the catalytic performance of cobalt 4-tert-butylbenzoate is superior, and the performance of the ICBBR is distinctly better than that of the batch stirred tank reactor (BSTR). The effects of reaction conditions such as flow rate, reaction temperature, and catalyst concentration on the oxidation of PTBT were studied. According to the distribution and kinetics of oxidation products, the oxidation mechanism of PTBT was analyzed. The results show that under the conditions of the oxygen flow rate of 2.5 L/min, reaction temperature of 150 °C and Co mass fraction of 250 ppm, the conversion rate of PTBT is 45.63% and the selectivity of PTBA is 97.8% after 4 h reaction without solvent. The reaction kinetics model of oxidation of PTBT to PTBA was established, and the reaction kinetics equation was obtained. The experimental values were close to the predicted values of the model.