微气泡分散对间甲基苯甲酸合成过程的强化作用

Strengthening effect of dispersive air microbubbles on synthesis process of m-toluic acid

传统的鼓泡塔间二甲苯(MX)氧化生产间甲基苯甲酸(MTA)工业过程中存在反应时间长、转化率低、选择性差等问题。在对物料平衡及反应速率控制步骤分析的基础上,研究了MTA的气相氧化及其微气泡强化分散合成过程。结果表明,采用微孔曝气可以得到平均直径30~100μm的微气泡,相界面面积较单管曝气增加了约300倍。当反应压力大于300 kPa时,高沸点酯类及MTA深度氧化副产物增多。在优化反应条件下(130℃、300 kPa、曝气100 L/(m^(3)·s)、钴催化剂摩尔分数为0.5‰)氧化反应5 h时,MX的转化率和MTA的生成率分别可达60.0%和45.0%,提高了氧化反应的效率和MTA的生成率,并且较同等条件下单管曝气的反应时间缩短了约1半。

In traditional industrial production process of m-toluic acid by the oxidation of m-xylene in a bubbling-tower,there have many problems such as long reaction time,low conversion rate and poor selectivity.On the basis of analyzing mass balance and control steps of the reaction,the gas-phase oxidation and strengthening dispersive microbubbles process for synthesizing m-toluic acid is studied experimentally.Results show that microbubbles with an average diameter of 30-100μm can be obtained by using microporous aeration,and the phase interface area is about 300 times that of single tube.As the reaction pressure is higher than 300 KPa,the production of high boiling point esters and by-products of m-toluic acid deep oxidation increase.Under optimal reaction conditions(130℃,300 kPa,100 L·m^(3)·s^(-1),0.5‰mol of cobalt catalyst),the conversion rate of m-xylene and the yield of m-toluic acid can reach 60.0%and 45.0%,respectively in 5 h.Both the efficiency of oxidation reaction and the yield of m-toluic acid can be significantly improved.Furthermore,under the same conditions,the reaction time is only about half that by single tube aeration.