甲苯液相氧化反应过程的模拟

Simulation of toluene liquid-phase oxidation

甲苯液相空气氧化是环境友好的苯甲酸和苯甲醛生产工艺。根据在模拟工业条件下测定的动力学数据和观察到的实验现象,提出了该反应的反应机理和反应网络,建立了相应的动力学模型。根据该动力学方程,对现有工业生产过程进行了模拟,发现现有工业过程处于严重供氧不足的情况。提出了3种强化方案并分别对其进行了模拟计算和比较。模拟结果表明,通过增大空气供给量和采用富氧空气氧化均可有效强化现有工业生产过程。采用富氧空气氧化,其甲苯转化率可提高到22.24%,甲苯反应量可增大57%。采用增大空气量的方法,可提高甲苯反应量31%,甲苯转化率可提高到18.61%。若同时增大甲苯和空气负荷,甲苯反应量可提高71%。

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.