金属掺杂类离子液体的双酸位构建及催化环己烯直接酯化研究

The highly efficient esterification of cyclohexene is the key and difficult problem of indirect synthesis of cyclohexene to cyclohexanol. The reaction mechanism shows that the selectivity of the reaction is difficult to control with Brønsted acid catalysts, and slow reaction ratio with Lewis acid catalysts, which lead to slow yield of cyclohexyl acetate. On the basis of the results obtained from the pre-research in our group, it is proposed in the project to design Brønsted-Lewis double acidic metal-doped ionic liquids to obtain highly efficient conversion of cyclohexene. Keeping this idea in mind, it is suggested to investigate the design and preparation of double acidic metal-doped ionic liquids, property characterization and catalytic performance evaluation. The structure-activity relationship between the structures and catalytic activities of ionic liquids will be studied in detail. The direct esterification reaction kinetic of cyclohexene will also be investigated. Several innovative achievements, including the design rule and preparation method of Brønsted-Lewis double acidic metal-doped ionic liquids, synergism of Brønsted and Lewis acid sites of ionic liquids, and the preliminary clean production technology of direct esterification of cyclohexene will be obtained after implementation. It is believed that this project may push the application and development of ionic liquids in the field of heterogeneous catalysis.

直接高效酯化环己烯是间接合成环己醇工艺的关键，反应机理表明其难点在于Brønsted酸催化剂的反应选择性难以控制，Lewis酸催化剂的反应速率慢，最终均导致产物环己酯收率较低。针对此关键问题，本项目在已有工作的基础上，创新性构建出具有Brønsted-Lewis双酸位的金属掺杂类离子液体催化体系，以期实现环己烯的直接高效酯化。围绕该思路，展开金属掺杂类离子液体的双酸位点结构设计、合成制备与性质表征，金属掺杂类离子液体的双酸位点结构与催化活性之间的构效关系，环己烯直接酯化反应非均相动力学过程等研究，最终获得高活性双酸位金属掺杂类离子液体的设计规律和制备方法，揭示金属掺杂类离子液体的Brønsted-Lewis酸性位点的协同作用机制，初步建立具有潜在工业应用前景的环己烯直接酯化新工艺。本项目的实施也将有助于拓宽离子液体催化材料在多相催化领域的应用。

环己烯与乙酸高效酯化是环己烯间接生产环己醇工艺的关键。针对酯化反应速率低、反应过程伴随副产物产生及乙酸环己酯收率偏低等问题， 本项目在离子液体上引入了双磺酸基官能团的Brønsted酸性位点，通过掺入不同的金属离子，将Lewis酸中心引入到多酸类离子液体，形成具有Brønsted-Lewis双酸位功能化化金属掺杂多酸类离子液体催化材料，并用于环己烯直接酯化合成乙酸环己酯过程中。与传统的酸性催化剂H2SO4、H3PMo12O40、H3PW12O40、H4SiW12O40及单一Brønsted功能化的多酸类离子液体相比，双酸位功能化金属掺杂多酸类离子液体呈现出良好的催化活性。实验还详细考察了催化剂用量、反应温度、反应物配比等因素对反应的影响，得出较佳的反应条件。建立了拟均相反应动力学模型，估算出相应的动力学参数，使计算值与实验值吻合良好。实验还考察了催化剂的重复使用性，催化剂重复使用6次，其催化活性无明显下降，显示出良好的重复利用性。在该项目的支持下，将功能化多酸类离子液体拓宽到其他酯化、水解、酯交换反应中，均显示出良好的催化活性及稳定性，显示出良好的应用前景。本项目的研究为乙酸环己酯的清洁合成工艺提供重要的基础理论依据，同时也拓宽离子液体在多相催化反应领域的应用。