Synthesis Of Mixed Plasticizer With Terephthalic Acid Residue

Terephthalic acid(TA) residue is a byproduct composed of inorginatic and organic impurities from the unit of PX oxidation to synthesize terephthalic acid, and the main components of TA residue are benzoic acid, p-methyl benzoic acid, m-phthalic acid, terephthalic acid and other impurities. Because of the complexity in components of TA residue, it is difficult to treat, and combustion and burying are two general methods, but which leads to environmental pollution. For us, TA residue has been the tie-in product with PTA residue for a long time, so PTA residue can not be returned to PX oxidation unit, and be only sold at a lower price than its own value, therefore, the economic benefit of PTA uint is decreased.This paper has analysed the synthetical utilization of TA residue, which were reported in some articles, and studied on the process of synthesizing mixed plasticizer with TA residue. The results show that the esterify reaction between TA residue and butanol has practicability and economic benefit. The esterify reaction also has several merits, such as low material cost, being apt to deal with product, producing high-boiling point solvent, butylether plasticizer, diglycol benzoic ether plasticizer,and the remnant solvent acted as low-end plasticizer or fuel of heater.After the studies, a valuable synthsis process was exploited to utilize TA residue, and the pilot experiment of some units were studied, a better research achievement was obtained in batch production. This technique will enable corporation to solve the problem of TA residue, which worries PTA unit for a long time, and enable PTA to return to PX oxidation unit. So PTA unit can increase productivity more than 1400 t/a, and biggish benefit will be got also. At mean time, the environmental pollution, brought by burying TA residue, will be avoided.