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PET often uses the following two synthetic methods: direct esterification of terephthalic acid (PTA) with ethylene glycol (EG) (PTA) and transesterification of dimethyl terephthalate (DMT) with ethylene glycol. Law (DMT method). The direct esterification method is a direct condensation of PTA and EG into an oligomer of terephthalic acid and ethylene glycol (bishydroxyethyl terephthalate BHET), followed by polycondensation. The transesterification process is to first convert the terephthalate to dimethyl terephthalate, and then to synthesize the polyester by transesterification. Compared with the transesterification method, the direct esterification method has the advantages of short process, low consumption and safe production. Direct esterification has been the main production process and preferred technical route for polyester since the 1980s.

The main raw materials for synthetic PET are: terephthalic acid (TPA), dimethyl terephthalate (DMT), and ethylene glycol (EG). The catalyst is mainly a metal compound such as a ruthenium catalyst, a ruthenium catalyst, or a titanium catalyst. Among them, the ruthenium catalyst has the highest activity and low side reaction, and the thermal degradation reaction to the polyester is low and the price is low, and the manufactured product has high quality, so it is most widely used. Commonly used lanthanide catalysts are ethylene glycol oxime, cerium acetate and antimony trioxide. However, the toxicity of bismuth compounds may adversely affect human health and the environment. In recent years, some countries in the world have put forward some new requirements for the use of earthworms. For example, the EU requires that less than 0.01 mg/kg of 锑 per kilogram of packaged materials transferred to food.