Polyethylene terephthalate PET is synthesized through a two-step process: esterification and polycondensation. The optimum reaction conditions for each step are as follows:1. Esterification:In the esterification step, terephthalic acid TPA reacts with ethylene glycol EG to form bis 2-hydroxyethyl terephthalate BHET .Temperature: The esterification reaction is typically carried out at temperatures between 220-260C.Pressure: The reaction is performed under atmospheric pressure.Catalyst: Esterification is an acid-catalyzed reaction. Common catalysts used in this step include antimony trioxide Sb2O3 , titanium IV isopropoxide Ti OiPr 4 , and zinc acetate Zn OAc 2 .2. Polycondensation:In the polycondensation step, BHET undergoes polymerization to form PET.Temperature: The polycondensation reaction is typically carried out at temperatures between 270-290C.Pressure: The reaction is performed under reduced pressure 0.1-1.0 mmHg to facilitate the removal of ethylene glycol, which is a byproduct of the reaction.Catalyst: Polycondensation is also an acid-catalyzed reaction. The same catalysts used in the esterification step can be used here, with antimony trioxide Sb2O3 being the most common.It is important to note that the optimum reaction conditions may vary depending on the specific process and equipment used. Additionally, the desired product properties, such as molecular weight and crystallinity, can be influenced by factors such as reaction time, catalyst concentration, and the presence of additives or co-monomers. Therefore, it is crucial to carefully control and optimize these parameters to achieve the highest yield and desired product properties.