SO_4^(2-)/TiO_2-La_2O_3固体超强酸催化合成乳酸乙酯

Synthesis of Ethyl Lactate with SO_4^(2-)/TiO_2-La_2O_3 Solid Acid as Catalyst

采用TiCl4和La(NO3)3.6H2O共沉淀法制备固体超强酸SO42-/TiO2-La2O3催化剂。制备条件为nTi/nLa比为8:1-,15℃陈化24h,120℃干燥12h,浸渍液硫酸浓度为0.5mol.L-1,浸渍4h,120℃干燥1h,400℃焙烧4h的催化剂对乳酸与乙醇的酯化反应有较高的活性。将此催化剂用于乳酸和乙醇合成乳酸乙酯的酯化反应,考察了催化剂用量、乙醇和乳酸的物质的量的比、反应时间、带水剂环己烷的用量对酯化反应的影响。实验结果表明,醇酸物质的量的为2.0:1,催化剂用量为所用乳酸质量的1.4%,环己烷为乙醇体积的78%,反应时间4h条件下酯化产率达82%。催化剂易回收,使用寿命长的优点。

A solid acid catalyst was prepared by coprecipitation in ammonia with La（NO3）3·6H2O and TiCh. Preparing conditions of the catalyst were molar ratio of TICl4 and La （NO3）3·6H2O 8：1, -15℃ aging time 24 h,drying at 120 ℃ for 12h, concentration of sulfuric acid 0.5 mol/L, impregnation time 4 h, drying at 120℃ for lh, calcination at 400 ℃ for 4h. As concerning synthesis of ethyl lactate, effects of catalyst dosage, molar ratio of ethanol to lactic acid, reaction time, dosage of water entrainer on esterification rate were studied. Under the optimal conditions of mole ratio of ethanol to lactic acid 2.0：1, reaction time 4 h, eyelohexane of 78% ethanol volume as water entrainer and mass of catalyst for 1.0% of lactic acid, esterification yield was 82 %. The solid superacid catalyst had the advantages of recycle and reusability.