Esterification of Diethylene Glycol Benzoate to Diethylene Glycol Dibenzoate Catalyzed by Sulfonated Carbon
Study on recovery of benzoic acid(BA)from the oxidation residue of pure terephthalic acid(PTA)to prepare the environmentally friendly plasticizer diethylene glycol dibenzoate(DEDB),which is used as a substitute for phthalate plasticizers,is of great importance.In this paper,the sulfonated activated carbon(SAC)catalyst was successfully prepared by loading—SO3H groups onto the surface of activated carbon(AC)through sulfonation.And the effects of catalyst concentration,reaction temperature,acid-alcohol molar ratio and the water-carrying agent toluene dosage on the direct esterification synthesis of DEDB were investigated using BA and diethylene glycol(DEG)as raw materials and SAC as catalyst.The optimal reaction conditions were as followed:the acid-alcohol molar ratio of BA to DEG was 2.2,the mass ratio of catalyst to BA was 2%,the mass ratio of water-carrying agent toluene to BA was 14%and the reaction temperature was 210℃.The conversion of BA was 90.1%and the yield of DEDB was 82.6%under the optimal reaction conditions.
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