Abstract In the liquid/liquid reaction of isobutane alkylation with C4 olefins, the solubility and diffusion properties of isobutane in catalyst phase exert substantial effect on the quality of alkylate. The solubility, diffusion, and permeability of isobutane and 2-butene in the 1-alkyl-3-methylimidazolium ionic liquids (ILs) with various anions including [BMIm][PF6], [BMIm][BF4], [BMIm][Tf2N] and [BMIm][Al2Cl7], and other ILs with different alkyl chains length including [BMIm][AlCl4], [HMIm][AlCl4] and [OMIm][AlCl4], as well as the H2SO4, were investigated using molecular dynamic simulation. Compared to H2SO4, the ILs were more favorable for the dissolution and diffusion of isobutane. The predicted isobutane solubility in ILs follows the order of [BMIm][Al2Cl7] > [BMIm][AlCl4] > [BMIm][Tf2N] > [BMIm][PF6] > [BMIm][BF4] for ILs with different anions, and [OMIm][AlCl4] > [HMIm][AlCl4] > [BMIm][AlCl4] for ILs with different alkyl chain length. The higher solubility of isobutane can be ascribed to the weaker cation-anion interaction, lower solubility parameter, and larger free volume. The isobutane diffusion follows the same trend as solubility for ILs with different anions, but opposite trend for ILs with various alkyl chain length. 2-butene shares the similar trend as isobutane, but shows a higher solubility and diffusion. In addition, isobutane and 2-butene permeability in ILs was estimated based on the solvation-diffusion mechanism. This work may help us better understand the structure-property of ILs for isobutane solubility and diffusion, and further provides new insights into the screening and design of novel ILs for the isobutane alkylation.

中文翻译：

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基于分子动力学模拟的异丁烷烷基化咪唑鎓离子液体的筛选

摘要 在异丁烷与C4烯烃的液/液烷基化反应中，异丁烷在催化剂相中的溶解性和扩散性对烷基化产物的质量有很大影响。异丁烷和 2-丁烯在 1-烷基-3-甲基咪唑鎓离子液体 (IL) 中的溶解度、扩散和渗透性，包括 [BMIm][PF6]、[BMIm][BF4]、[BMIm][Tf2N] ] 和 [BMIm][Al2Cl7]，以及其他具有不同烷基链长度的离子液体，包括 [BMIm][AlCl4]、[HMIm][AlCl4] 和 [OMIm][AlCl4]，以及 H2SO4，使用分子动力学进行了研究模拟。与 H2SO4 相比，离子液体更有利于异丁烷的溶解和扩散。ILs 中预测的异丁烷溶解度遵循以下顺序 [BMIm][Al2Cl7] > [BMIm][AlCl4] > [BMIm][Tf2N] > [BMIm][PF6] > [BMIm][BF4] 用于具有不同阴离子的离子液体，[OMIm][AlCl4] > [HMIm][AlCl4] > [BMIm][AlCl4] 用于具有不同烷基链长度的离子液体。异丁烷较高的溶解度可归因于较弱的阳离子-阴离子相互作用、较低的溶解度参数和较大的自由体积。异丁烷扩散的趋势与具有不同阴离子的离子液体的溶解度相同，但具有不同烷基链长度的离子液体的趋势相反。2-丁烯与异丁烷具有相似的趋势，但显示出更高的溶解度和扩散性。此外，ILs 中的异丁烷和 2-丁烯渗透率是根据溶剂化扩散机制估算的。这项工作可能有助于我们更好地了解异丁烷溶解度和扩散的离子液体的结构特性，