Abstract:

To decrease the usage of ionic liquid and facilitate the separation of catalyst from the product, a novel Brønsted acidic ionic liquid catalyst of 1-(3-sulfopropyl)caprolactam hydrogen sulfate ([C₃SO₃HCP]HSO₄) supported on SBA-15 was prepared through covalent bond grafting method. In order to achieve structural information and stability of catalysts, the samples were characterized by FT-IR, TG, XRD, BET and TEM techniques. The catalytic activities of the immobilized ionic liquid for the esterification of succinic anhydride with ethanol were investigated. It showed that [C₃SO₃HCP]HSO₄ has been successfully immobilized onto the SBA-15 with relatively good thermal stability and catalytic activity, which overcomes the drawbacks of low activity of heterogeneous catalyst, and difficult separation of homogeneous catalyst from the reaction system. Under the optimized conditions of 5%(mass) of catalyst dosage, n(C₄H₄O₃):n(C₂H₅OH)=1:3, 80℃ of reaction temperature, 4 h of reaction time, and 30%(mass) of water carrying agent dosage, the yield of diethyl succinate was up to 93.7%. The SBA-15 immobilized ionic liquids remained satisfactory catalytic activity for the synthesis of diethyl succinate after 8 cycles. Moreover, the IL/SBA-15 exhibited relatively high yield of diethyl succinate for a series of esterification and the product could be separated easily from the reaction system.

Key words: SBA-15, immobilization, ionic liquid, esterification, catalyst

摘要：

为了减少离子液体用量及解决催化剂分离问题,采用键合法制备了以SBA-15为载体的固载化离子液体催化剂[C₃SO₃HCP]HSO₄/SBA-15,通过FT-IR、TG、XRD、BET和TEM分析了催化剂的结构和稳定性。并将其应用于催化丁二酸酐和乙醇的酯化反应。结果表明:[C₃SO₃HCP]HSO₄被成功固定在SBA-15上,且具有较高的热稳定性和催化活性,克服了非均相催化剂活性不高与均相催化剂难以分离的不足。在催化剂用量为反应物总质量的5%、n(C₄H₄O₃):n(C₂H₅OH)=1:3,反应温度80℃;反应时间4 h、带水剂用量为反应物总质量的30%的条件下,酯收率达93.7%,且该催化剂循环使用8次后,仍具有较高的催化活性。此外,还考察了以[C₃SO₃HCP]HSO₄/SBA-15为催化剂催化合成系列酯也获得了较高的酯收率,且易于与产物酯分离。

关键词: SBA-15, 固定化, 离子液体, 酯化反应, 催化剂