PW/MCM-41催化剂的合成及对合成柠檬酸三丁酯反应的研究

制备了负载H₃PW₁₂O₄₀(PW)杂多酸的PW/MCM-41催化剂，用XRD和BET等方法表征了催化剂的结构。在负载质量分数达40%的催化剂上，XRD未检测到PW杂多酸的晶相峰。考察了不同负载质量分数的 PW/MCM-41催化剂对反应的影响。重点讨论了催化剂的活化温度、酸醇摩尔比和反应温度等因素对酯化反应的影响。最佳操作条件：PW/MCM-41负载杂多酸催化剂的磷钨酸最佳负载质量分数 40%，催化剂焙烧温度300 ℃，酸醇摩尔比1∶4，反应温度140 ℃，反应时间6～7 h。实验结果表明，负载质量分数为40%的PW/MCM-41催化剂是替代硫酸合成柠檬酸三丁酯的理想催化剂，且稳定性良好。

Synthesis of PW/MCM-41 catalyst and its performance in synthesis of tri-n-butyl-citrate

PW/MCM-41 catalysts consisting of H₃PW₁₂O₄₀ heteropoly acid (PW) supported on MCM-41，a mesoporous molecular sieve， was prepared and the pore structure characterized by XRD and BET. PW crystal phase was not observed in XRD patterns at PW loading of as high as 40%. The effects of PW loadings on the reaction was investigated. The influences of calcination temperature, citric acid /butanol molar ratio and reaction temperature on the esterification reaction were investigated, too. The optimum reaction condition was obtained as follows: PW loading = 40%, calcination temperature =130 ℃, citric acid /butanol molar ratio = 1∶4, reaction temperature =140 ℃, and reaction time = 6～7 h.The experimental results showed that PW(40)/MCM-41 is an ideal substitute for sulfuric acid as the catalyst for synthesis of tri-n-butyl-citrate with high and stable activity.