Application of Phosphotungstic Acid-Zn/Al Hydrotalcite-like Hybrid Catalyst in the Preparation of Phthalic Acid Di(2-ethylhexyl) Ester

A phosphotungstic acid-Zn/Al hydrotalcite-like hybrid catalyst was prepared with terephthalic acid anions as support body and applied in the catalytic synthesis of phthalic acid di(2-ethylhexyl) ester(DOP).The effect of reaction conditions such as raw material ratio,amount of catalyst,reaction temperature,reaction time on the conversion of phthalic anhydride was investigated.Moreover,the reusability of this catalyst was also discussed under the optimum reaction conditions.It was found that the synthesized phosphorus acid-Zn/Al hydrotalcite-like hybrid catalyst is a good catalyst in the synthesis of DOP.When 0.76% catalyst amount,2.5 anhydride/alcohol molar ratio,180 ℃ reaction temperature,4.5 h reaction time were employed,the conversion of phthalic anhydride was 92.8%,then could be up to 97.9% for 10 h.The catalytic activity of the reusable catalyst decreased slightly,however,it can be basically recovered via washing the catalyst with ethanol to regenerate.