Synthesis of dioctyl maleate by solid acid S_2O_8~(2-)/ZrO_2-SiO_2 catalyst

The solid acid catalyst S2O2-8/ ZrO2 SiO2 was prepared by impregnating zirconiumsilicon composite oxide with peroxodisulfate. The catalytic activity was studied in the esterfication of maleic anhydride to noctyl alcohol, and compared with sulfuric acid and ptoluene sulfonic acid. The results showed that the promotion role of S2O2-8 was higher than of SO2-4.The catalyst S2O2-8/ ZrO2 SiO2 prepared under the optimal conditions,such as molar ratio of zirconia to silicon was 1∶6, concentration of (NH4)2S2O8 0.7 mol/L, impregnation 12 h,calcination at 550 ℃ for 3 h,had splendid catalytic activity for the synthesis of dioctyl maleate,and the product was colorless and transparent.The yield of dioctyl meleate was over 98.4% in reaction time 3 h,18% over than that with catalyst SO2-4/ZrO2SiO2 under the same conditions.