催化裂化柴油馏分在离子液体中扩散行为的分子动力学模拟

MOLECULAR DYNAMICS SIMULATION ON THE DIFFUSION BEHAVIOR OF FCC DIESEL FRACTIONS IN IONIC LIQUIDS

为了研究催化裂化柴油馏分烃分子在离子液体1-己基-3-甲基咪唑四氟硼酸盐([C_(6)mim][BF_(4)])中的扩散行为,采用分子模拟方法,以烃分子[C_(6)mim][BF_(4)]共混模型体系为研究对象,计算不同烃分子在[C_(6)mim][BF_(4)]体系中的均方位移,分析烃分子与[C_(6)mim][BF_(4)]的相互作用,并讨论烃分子尺寸对共混体系自由体积分数的影响。结果表明:饱和烃分子比芳烃分子更容易在[C_(6)mim][BF_(4)]体系中进行扩散;饱和烃分子与[C_(6)mim][BF_(4)]的相互作用以范德华作用为主;随着芳烃环数增多,芳烃分子与[C_(6)mim][BF_(4)]的静电作用逐渐增强,对于三环芳烃,静电作用是其与[C_(6)mim][BF_(4)]间的主要相互作用。分子体积越小、与离子液体相互作用越强的烃分子对应的共混体系自由体积分数越小。

In order to study the diffusion behavior of hydrocarbon molecules from FCC diesel fractions in ionic liquid 1-hexyl-3-methylimidazolium tetrafluoroborate([C_(6)mim][BF_(4)]),a molecular simulation method was used to study the diffusion behavior of hydrocarbon molecules in the blend model system of the hydrocarbons molecules and[C_(6)mim][BF_(4)].The mean square displacement of different hydrocarbon molecules in the[C_(6)mim][BF_(4)]system were calculated,and the interactions between hydrocarbon molecules and[C_(6)mim][BF_(4)]were analyzed.The results show that saturated hydrocarbon molecules diffuse more easily in the[C_(6)mim][BF_(4)]system than aromatic hydrocarbon molecules,and the interaction between saturated hydrocarbons and[C_(6)mim][BF_(4)]is dominated by van der Waals interaction.As the number of aromatic rings increases,the electrostatic interaction between aromatic molecules and[C_(6)mim][BF_(4)]is gradually enhanced.For tricyclic aromatic hydrocarbons,the electrostatic interaction is the main interaction between[C_(6)mim][BF_(4)]and aromatic hydrocarbons.The smaller the molecular volume is,the stronger the interaction with the ionic liquid is,and the smaller the free volume fraction of the blends is.