What are the connections and differences among PTA, PX and PET?

PTA stands for purified terephthalic acid \x0d\PX stands for para-xylene \x0d\PET stands for polyethylene terephthalate \x0d\PTA is widely used. More than 90% of PTA in the world is used to produce polyethylene terephthalate (PET), and the rest is used to produce polypropylene terephthalate (PTT). PTA production process can be divided into two parts: oxidation unit and hydrofining unit. The raw material PX is oxidized into crude terephthalic acid by air with acetic acid as solvent under the action of catalyst, and then the crude product is obtained by crystallization, filtration and drying in turn. Crude terephthalic acid is hydrogenated to remove impurities, then crystallized, centrifugally separated and dried to obtain PTA products.