Abstract:

Propane sulfonate (PS) functionalized organic cations were combined with Keggin heteropolyanions to synthesize a series of sulfonated organic heteropolyacid salts (HPA-ILs). Their structures were characterized by FT-IR and elemental analyses (C, H, N). These catalysts were applied to directly catalyze the esterification of ammonium succinate with 1-butanol in aqueous solution. Compared with HPAs, H₂SO₄, [MIMPS]HSO₄ and Nafion^®NR-50 resins, HPA-ILs exhibited excellent catalytic activities. Finally, the excellent catalyst [MIMPS]₃PMo₁₂O₄₀ was selected to investigate systemically the reaction conditions. The optimization of the reaction conditions was ammonium succinate concentration 50% (mass), catalyst dosage 1.0% (based on ammonium succinate), n(1-butanol):n(ammonium succinate)=5:1, reaction time 12 h, reaction temperature 130℃ and vacuum degree 0.02 MPa. The highest yield of esters could reach 89.7%. After reusing 6 times the catalyst still showed the superior catalytic performance with yield of above 85%.

Key words: ionic liquids, heteropolyacid salts, functionalized, catalysis, ammonium succinate aqueous solution, esterification

摘要：

将磺酸功能化离子液体有机阳离子与Keggin结构的杂多酸(HPAs)阴离子结合,合成一系列磺酸功能化离子液体杂多酸盐(HPA-ILs),并对其结构进行了表征。将合成的杂多酸盐作为催化剂应用于丁二酸铵水溶液与正丁醇的直接酯化。与HPAs、H₂SO₄、[MIMPS]HSO₄和Nafion^®NR-50 resins等传统催化剂相比,HPA-ILs表现出更好的催化性能,并以 [MIMPS]₃PMo₁₂O₄₀作催化剂,详细探讨并确定了本反应的最佳工艺条件。在丁二酸铵质量分数为50%,催化剂质量分数为1.0%(以丁二酸铵计),醇铵摩尔比为5:1,反应时间为12 h,反应温度为130℃,真空度为0.02 MPa时,最佳酯收率达89.7%。催化剂重复使用6次后,酯收率仍保持在85%以上。

关键词: 离子液体, 杂多酸盐, 功能化, 催化, 丁二酸铵水溶液, 酯化