The oxidation reaction mechanisms of p-xylene in the reactor are studied in detail. Based upon the reaction by-products of trimellitic acid, benzene carboxylic acid, m-phthalic acid and o-phthalic acid, etc, it is concluded that the trimellitic acid and part of benzene carboxylic acid, m-phthalic acid and o-phthal-ic acid are the products of disproportionation and isomerization reactions of terephthalic acid. It is pointed out that the m-xylene and o-xylene can also react like p-xylene to form m-phthalic acid and o-phthalic acid, while the other part of benzene carboxylic acid is the product from the oxidation reaction of toluene in PX feed. A p-xylene oxidation reactor simulation model is established by using PRO/ II simulation software. When the operating pressure of PX oxidation reactor is the same as the design pressure and reaction temperature is at 191 ℃, the temperature calculated by reactor simulation model is 192. 6℃, which is very close. The difference between simulation data and reference data is within acceptable range, which can be applied in the engineering design of PTA plant. The PX oxidation reactor simulation model has been successfully applied in the revamping of a PTA plant in a refinery.%对对二甲苯(PX)氧化反应器的反应机理作了深入的研究.认为偏苯三酸和一部分苯甲酸、间苯二甲酸和邻苯二甲酸等副产物是由对苯二甲酸分别发生歧化和异构化反应而生成的；PX原料中的杂质间二甲苯和邻二甲苯也会经历类似对二甲苯反应历程分别生成间苯二甲酸和邻苯二甲酸；另一部分苯甲酸则由PX原料中的杂质甲苯氧化生成.利用PRO/Ⅱ模拟软件建立了PX氧化反应器模拟模块,当PX氧化反应器操作压力与设计数据相同,反应温度为191℃,反应器模拟模块计算值为192.6℃,两者非常接近.经对比,模拟结果与参考数据的偏差在可接受的范围内,可以应用于PTA装置的工程设计.对二甲苯氧化反应器模拟模块已在PTA装置扩能改造设计中得到应用.
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