PROCESS OF DESTRUCTION OF TEREPHTHALIC ACID IN SUPERCRITICAL WATER

摘要

Terephthalic acid (TA) is one of the important technical compounds. It is used in large quantities in the synthesis of polyetheleneterephthate (PET) and different other organic productions such as the preparation of polyester resins. World production of TA reached millions of tons/year, and the tendency here is towards the growth. In many cases using of TA is determined by its properties, and in particular, the dimensions and form of its crystals, degree of its purity, etc. These properties are considerably modified by autoclave treatment of TA. It is interesting, in this occasion, to study the behavior of TA in contact with water fluid or vapor under critical or supercritical conditions. Previously [1] we show that TA can be obtained from autoclave treatment of PET items. In many cases TA with extremely small particles is formed. The increasing of the size of these crystals is a separate problem which has to be solved. Re-crystallization using autoclave treatment was identified in paper [2]. In this study, a detailed investigation of the growth crystal process of TA in under- and supercritical intervals of water vapor pressure is carried out.