Abstract:

The intensification of the Brønsted acidic ionic liquids (BILs) with different alkyl chain lengths with or without the sulfonic acid groups on the interfacial behaviors of H₂SO₄/C₄ hydrocarbons were studied by molecular dynamic (MD) simulation. The results indicated that the introduction of BILs into the H₂SO₄ can contribute to a better dissolution and diffusion of C₄ hydrocarbons at the interface compared to the pure H₂SO₄, which is helpful to the quality of alkylate. The stronger density enrichment at interface can be found for the cations with longer alkyl chains with their alkyl chains protruding more deeply into the C₄ hydrocarbons phase, which is beneficial to the enhancement of the interfacial properties. The longer alkyl chains can facilitate the dissolution of C₄ hydrocarbons, but increase the survival probability at the interface and limits their interfacial diffusion. Compared to the non-SFILs, the sulfonic-acid-functionalized ILs (SFILs) can facilitate a higher dissolution of isobutane but inhibit its diffusion at the interface. In this work, the intensification on the interfacial behaviors of C₄ alkylation provide deeper understanding of the C₄ alkylation process. The related results are expected to help the alkylation process strengthening and optimization and design of new catalysts.

Key words: MD simulations, Brønsted ionic liquids, liquid/liquid interface, alkylation, SFILs

摘要：

利用分子动力学（MD）模拟研究了不同支链长度以及官能团的Brønsted酸性离子液体（BILs）对H₂SO₄/C₄烷烯界面特性的调控。结果表明，BILs的加入可以明显增强C₄烷烯在两相界面处的溶解和扩散，有利于烷基化油品的提升。烷基链较长的阳离子表现出较强的界面密度富集现象，并且其支链倾向于伸入C₄烷烯相，有利于界面性质的增强。阳离子支链的增长能够促进C₄烷烯的溶解，同时增大了C₄烷烯的界面存留率，不利于其界面扩散。另外，相比于非磺酸功能化离子液体（non-SFILs），磺酸功能化离子液体（SFILs）促进了C₄烷烯的溶解，但抑制了C₄烷烯的扩散。本文在C₄烷基化界面性质方面的研究有利于深入理解C₄烷基化过程，相关结果有望为烷基化过程强化和新型催化剂的优化和设计提供帮助。

关键词: MD模拟, Brønsted离子液体, 液液界面, 烷基化, SFILs