Synthesis of diethylene glycol dibenzoate over immobilized acidic ionic liquid

Acid ionic liquid 1-butylsulfonate-3-methyl imidazole p-tosylate ([(CH₂)₄SO₃HMIm]TS) is immobilized on the chromatography SiO₂ by sol-gel, impregnation and grafting methods respectively.Its catalytic performance in the synthesis of diethylene glycol dibenzoate (DEBD) is investigated.The results indicate that the catalyst NJ-4.0 prepared by sol-gel method shows the best catalytic efficiency.The optimized synthetic conditions for DEDB are gained through experiments as follows: reaction temperature is at 165℃, reaction time lasts for 4 h, n(benzoic acid):n(diethylene glycol)=2.2:1, the mass ratio of catalyst NJ-4.0 to diethylene glycol is 8wt%.Under the optimal conditions, the yield of DEDB can reach 86.2%.