S_2O_8^(2-)/ZrO_2-Al_2O_3的制备、表征及其催化合成富马酸二甲酯

PREPARATION,CHARACTERIZATION AND PERFORMANCE OF NANOSOLID SUPERACID S_2O_8^(2-)/ZrO_2-Al_2O_3 FOR SYNTHESIS OF DIMETHYL FUMARATE

采用浸渍-沉淀法制备出纳米固体超强酸催化剂S_2O_8^(2-)/ZrO_2-Al_2O_3,通过正交实验得到最佳制备条件:Al_2O_3质量分数2.0%,-15℃陈化24 h,浸渍液(NH_4)_2 S_2O_8浓度0.8 mol/L,焙烧温度650℃,焙烧时间3 h。用XRD、TEM、BET、TG-DTG和化学分析手段分析了S_2O_8^(2-)/ZrO_2～Al_2O_3的晶化过程、比表面积、含硫量和热稳定性。结果表明,在焙烧温度为500～650℃时制备的催化剂属纳米材料(粒径<41 nm),有较大比表面积和较好的热稳定性;富马酸二甲酯的最佳合成条件为:n(甲醇):n(富马酸)=6.0:1.0,S_2O_8^(2-)/ZrO_2- Al_2O_3用量1.5%,带水剂苯用量10 mL,反应时间4.0 h,催化剂重复使用6次,酯化率大于90%。

Nanometer composite solid superacid catalyst S2O8^2-/ZrO2-Al2O3 was prepared by an impregnation - precipitation method. The optimum preparation conditions were found as follows： 2.0% Al2O3, ageing temperature -15 ℃, ageing time 24 h, 0.8 mol/L （NH4）2S208, activation tempereature 650 ℃, and activation time 3 h. The crystallization process, specific surface area, sulphur content and thermal stability of S2O8^2-/ZrO2-Al2O3 were studied by XRD, TEM, BET, TG-DTG and chemical analysis. Based on the orthogonally-designed experiments, the optimum conditions for the synthesis of dimethyl fumarate were found as follows： molar ratio of carbinol to fumaric acid 6.0 ： 1.0, mass of the catalyst 1.5% （relative to the total mass ratio ）, 10 mL benzene as water carrying reagent, and reaction time 4.0 h. The catalyst exhibited good stability with the conversion of acetic acid still up to 90% after 6 runs.