强酸介质中离子簇的形成机理及调控机制

The mixtures of ionic liquid/strong acid are shown to be efficient catalytic systems which can enhance the alkylation of isobutane/butene, an important process producing ideal gasoline blending components with high octane numbers. The unique performance of ionic liquids in this process is closely related to the microstructures of the ionic liquids in the systems. In this proposal, molecular simulation and spectroscopic characterizations, including Nuclear Magnetic Resonance, Infrared Spectroscopy, Raman Spectroscopy, Fourier Transform Ion Cyclotron Resonance Mass Spectroscopy, High Resolution Transmission Electron Microscope, X-Ray Scattering, Neutron Diffraction, etc., will be combined to study the specific mixtures of ionic liquid/strong acid, which could enhance the alkylation of isobutane and butene. The microstructure and aggregation behaviors in the ionic liquid solutions will be investigated, and the formation mechanism of the ionic clusters will be proposed. Also, the influence of external conditions on the microstructure changes in the systems will be investigated. Moreover, the essential relationship between the structures of the ionic clusters and the catalytic activity of ionic liquid/strong acid in the isobutane/butene alkylation process will be set up. This study will give some academic evidence for the high catalytic activity of this kind of catalytic system, and could also provide theoretical guidance for the development of more economic and efficient alkylation catalysts.

离子液体/强酸为强化异丁烷/丁烯烷基化反应的有效催化剂，该反应是生产高辛烷值汽油调和组分的重要工艺。离子液体优异的性能与其在体系中的微观结构密切相关。本项目拟采用分子模拟和光谱表征相结合的方法，包括核磁共振、红外光谱、拉曼光谱、傅里叶变换离子回旋共振质谱、高分辨率透射电镜、X-射线散射、中子衍射等，对能强化异丁烷/丁烯烷基化反应的特定离子液体/强酸混合体系进行综合研究，分析溶液中的微观结构和团簇行为，揭示离子簇形成机理，探索外界条件变化对离子簇结构的调控机制，并建立离子簇结构与其在异丁烷/丁烯烷基化反应中催化活性之间的本质关系。本研究的开展将为离子液体/强酸体系的高催化活性提供理论依据，同时为研发更经济有效的烷基化反应催化剂提供理论指导。

异丁烷/丁烯烷基化反应是生产高辛烷值汽油调和组分的重要工艺，离子液体可显著改善硫酸催化烷基化反应的产物分布，离子液体（IL）优异性能与其在体系中的微观结构密切相关。本项目采用分子模拟和光谱表征相结合的方法，研究了特定IL/H2SO4体系的微观结构和团簇行为，揭示了离子簇形成规律及机制。发现离子液体的阴离子可与硫酸形成离子簇，如：[HSO4∙∙∙(H2SO4)n]-，从而减弱离子液体中阴阳离子相互作用，进而使得反应体系中阳离子更易与烷烃/烯烃作用（主要通过烷基链），提高催化剂与碳氢化合物的互溶性。研究中，结合IL/H2SO4体系微观结构、酸性、表面张力、异丁烷在催化体系的溶解性，阐明了具有表面活性作用的离子液体强化硫酸催化异丁烷/丁烯烷基化反应的机理，即催化体系离子簇的形成可以稳定酸强度，离子液体的存在大幅度提高了反应原料在催化剂中的溶解性，从而可促进烷基化反应决速步中氢负离子由异丁烷向C8正离子的转移，更有利于目标产物三甲基戊烷的生成，抑制副反应的发生及酸溶油的生成，进而提高烷基化油品质、减少体系废酸排放。该研究获得了可提高油品品质、大幅降低烷基化过程酸耗、缓解环境压力的催化体系，并为开发催化活性更优异的催化剂提供了理论依据。