Synthesis of Tributyl Citrate Catalyzed by Compound Solid Superacid SO_4~(2-)/ZrO_2-TiO_2

Tributyl citrate(TBC)was synthesized using compound solid superacid SO2-4/ZrO2-TiO2 as catalyst.The effects of the dosage of catalyst SO2-4/ZrO2-TiO2,the molar ratio of raw materials and the terminal reaction temperature on the reaction were studied.The product structure was analyzed by means of IR spectroscopy.The optimum conditions for the synthesis of TBC over SO2-4/ZrO2-TiO2 were as follows: dosage of catalyst(based on the mass of total reactant) was 1.5%～2.0%;molar ratio of citric acid to n-butanol was 1∶(4.5～5.0);terminal reaction temperature was 140～145℃ and reaction time was 3.5 h.The yield reached over 98.5% under the optimum conditions and the product quality met or exceeded national quality product standard.The catalyst,which had no corrosion and little environmental pollution and was easy to regenerate,could be used repeatedly for 5 times with the yield still around 98.5%.