Preparation method of dioctyl terephthalate

The invention provides a method for preparing dioctyl terephthalate through catalyzing the waste PET (polyester) isooctanol alcoholysis reaction. The method is characterized in that heptamul ferrocene 1-(3-sulfoacid propyl)-3-methylimidazole is used as a catalyst for catalyzing the PET isooctanol alcoholysis reaction; under the conditions that the mass ratio of PET structure units to isooctanol substances being 1:5 to 1:8, the mass ratio of the PET to the catalyst being 1000:1 to 100:3, the reaction temperature being 180 to 245 DEG C and the reaction time being 2 to 8h, the dioctyl terephthalate is prepared; ethylene glycol is recovered. Compared with the prior art, the method has the advantages that the ingredients are more economic; 2, the product is not dissolved in the dioctyl phthalate and the catalyst, and can realize automatic layer separation, so that the separation process is easier; 3, the consumption of the catalyst is low, and the catalyst can be cyclically used; 4, the reaction time is short.