摘要
通过离子交换法制备了一系列季铵盐(苄基三乙基氯化铵、四丁基溴化铵和十六烷基三甲基溴化铵)和锆盐(ZrCl4)共掺杂磷钨酸催化剂.利用SEM、FTIR、XRD、XPS、TGA-DTG及正丁胺电位滴定法对催化剂进行了表征,并对其催化乙二醇与苯甲醛的缩醛反应性能进行了考察.采用单因素和响应面实验考察了催化剂用量(以苯甲醛质量为基准,下同)、n(乙二醇)∶n(苯甲醛)、带水剂(环己烷)用量和反应时间对苯甲醛乙二醇缩醛(BEGA)产率的影响,并考察了催化剂的重复使用性能.结果表明,四丁基溴化铵(TB)和ZrCl4共掺杂的磷钨酸催化剂TB0.5Zr0.5H0.5PW具有最优异的催化性能,催化剂强的Brønsted与Lewis酸中心间的协同效应及"假液相"特性是其具有高活性的原因;以TB0.5Zr0.5H0.5PW为催化剂,经响应面优化制备BEGA最佳工艺条件为n(乙二醇)∶n(苯甲醛)=1.5∶1、催化剂用量为1.9%、反应温度110℃、反应时间3 h、带水剂用量12.6 mL,在该条件下BEGA产率为94.6%;TB0.5Zr0.5H0.5PW使用6次后,BEGA产率为91.9%.
Abstract
A series of quaternary ammonium salts(benzyl triethyl ammonium chloride,tetrabutylammonium bromide and hexadecyl trimethyl ammonium bromide)and zirconium salt(ZrCl4)co-doped phosphotungstic acid catalysts were prepared by ion exchange method,characterized by SEM,FTIR,XRD,XPS,TGA-DTG,as well as n-butylamine potentiometric titration method,and evaluated on their catalytic performance for acetalization of benzaldehyde and glycol.The effects of catalyst amount(based on the mass of benzaldehyde,the same below),n(ethylene glycol)∶n(benzaldehyde),water carrying agent(cyclohexane)amount and reaction time on the yield of benzaldehyde glycol acetal(BEGA)were investigated through single factor and response surface experiments,the reusability of the catalyst was also explored.The results showed that the phosphotungstic acid catalyst TB0.5Zr0.5H0.5PW co-doped with tetrabutylammonium bromide(TB)and ZrCl4 exhibited the best catalytic performance,with its high catalytic activity attributed to the fact that the strong synergistic effect between Brønsted and Lewis acid centers,and"pseudo liquid phase"characteristics.Under the catalysis of TB0.5Zr0.5H0.5PW,the yield of BEGA could reach 94.6%under the optimized conditions via response surface experiments with n(glycol)∶n(benzaldehyde)of 1.5∶1,catalyst amount of 1.9%,reaction temperature of 110℃,reaction time of 3 h,and cyclohexane amount of 12.6 mL.The yield of BEGA was maintained at 91.9%with TB0.5Zr0.5H0.5PW recycled 6 times.
基金项目
国家级大学生创新创业训练计划(202310353083)
NETL
NSTL
万方数据