硅烷偶联剂改性SBA-15固载Keggin型杂多酸催化合成柠檬酸三丁酯

以3-(甲基丙烯酰氧)丙基三甲氧基硅烷(MEMO)表面改性的介孔分子筛SBA-15为载体,制备了一系列介孔分子筛/硅烷偶联剂@杂多酸复合催化剂SBA-15/MEMO@HnXW12O40(X=P⁵+,Si⁴⁺,B³⁺;n=3,4,5),并利用FTIR、P-XRD、TEM、N2吸附-脱附对其结构进行表征。以SBA-15/MEMO@HnXW12O40(X=P⁵⁺,Si⁴⁺,B³⁺;n=3,4,5)为负载型杂多酸催化剂对柠檬酸三丁酯的催化合成进行研究,分别考察了酸醇摩尔比、催化剂用量、反应温度、反应时间对催化合成柠檬酸三丁酯酯化率的影响,并获得合成柠檬酸三丁酯的最佳工艺条件。结果表明:当负载型硅钨酸催化剂的负载量为50%、催化剂用量为3.8%、酸醇摩尔比为1∶4、反应温度为140℃、反应时间为6 h、环己烷用量为5 mL时酯化率可达97.56%,重复使用7次后酯化率仍可达62.67%。

Synthesis of tributyl citrate catalyzed by silane coupling agent modified SBA-15 supported Keggin type heteropoly acid

A series of mesoporous molecular sieve/silane coupling agent@heteropoly acid composite catalysts SBA-15/MEMO@HnXW12O40(X=P⁵⁺,Si⁴⁺,B³⁺;n=3,4,5)were prepared,employing mesoporous molecular sieve SBA-15 modified by 3-(methacryloyloxy)propyltrimethoxysilane(MEMO) as supporter.And the structure was characterized by FTIR,P-XRD,TEM and N2 adsorptiondesorption.The catalytic synthesis of tributyl citrate was studied using the SBA-15/MEMO@HnXW12O40(X=P⁵⁺,Si⁴⁺,B³⁺;n=3,4,5) as supported heteropoly acid catalysts.The effects of molar ratio of acid to alcohol,catalyst dosage,reaction temperature and reaction time on the esterification rate of tributyl citrate were investigated respectively,and the optimum conditions for the synthesis of tributyl citrate were obtained.The results showed that the esterification rate could reach 97.56% when the supported silicotungstic acid catalyst loading was 50%,the catalyst dosage was 3.8%,the molar ratio of acid to alcohol was 1:4,the reaction temperature was 140 ℃,the reaction time was 6 h and the amount of cyclohexane was 5 mL.And the esterification rate could still reach 62.67%after 7 times of recycling.