Zirconia-loaded sulfuric acid (SO24- /ZrO2) catalysts were prepared by impregnation method, molded by punch tablet machine and characterized by X-ray diffraction. SO42- /ZrO2 catalyst was used to obtain glycerol triacetate (GTA) directly from glycerin. The effect of some factors, such as different temperatures of calcination and catalysts molded or not, on the reusable times of catalysts and the yield of GTA were investigated. The optimum reaction conditions were shown as follows: the reaction temperature was 403 K; the reaction time continued for 8 h; the amount of molded catalysts was 5 wt% of glycerin and the molar ratio of glycerin to acetic acid was 1 : 8. The yield of GTA was 97.93% under the optimum condition.
采用先酯化后共聚的方法合成聚羧酸系减水剂,考察以甲基丙烯酸(MMA)和甲氧基聚乙二醇(MPEG)为原料酯化合成大单体甲氧基聚乙二醇甲基丙烯酸酯(MPEGMA)过程中阻聚剂对苯二酚用量、酸醇摩尔比、反应温度等对酯化率的影响.以大单体MPEGMA与马来酸酐、MMA和2-丙烯酰胺基-2-甲基丙烷磺酸共聚合成聚羧酸类减水剂,考察减水剂合成过程中MPEG相对分子质量和引发剂过硫酸铵用量以及减水剂掺量对减水剂性能的影响.结果表明:阻聚剂质量分数为0.4%、酸醇摩尔比为1.5∶1、反应温度为120℃时,酯化率可达到92.3%.当MPEG相对分子质量为1 000、引发剂的质量分数为5%,合成的减水剂掺量质量分数为0.3%时,水泥的净浆流动度可达281 mm.
