多环芳烃在超临界环己烷中的溶解：分子动力学模拟研究

重油中大量存在的多环芳烃会经过缩合反应会形成稠环芳烃，而溶解扩散的限制会导致稠环芳烃之间的聚合从形成残焦，使得对重油的利用率大大降低，所以多环芳烃热解过程的溶解扩散是重油改质的关键因素之一.因此，基于环己烷对烃类良好的溶解性，本文采用分子动力学模拟的方法研究了多环芳烃及其混合物在超临界环己烷中的溶解行为，结果表明在不同温度与密度下超临界环己烷对于具有NAP均具有良好的溶解性，而温度对于Bghip溶解的影响较小.在多环芳烃混合物的油滴溶解过程中，NAP优先溶解到环己烷相中，而Bghip则集中在粒径减小的油滴中.通过计算体系中多环芳烃的径向分配函数与溶剂化自由能发现环己烷与多环芳烃间之间能相互吸引，环己烷在多环芳烃分子周围形成的溶剂壳能抑制多环芳烃分子间的聚合.温度升高以及密度的将降低会导致多环芳烃的内聚能密度降低，增加了多环芳烃与超临界环己烷之间的相互作用.环己烷密度越小以及温度的升高可以促进多环芳烃或多环芳烃混合物在超临界环己烷中的溶解.

Dissolution of polycyclic aromatic hydrocarbons in supercritical Cyclohexane: A molecular dynamics simulation study

There are large number of polycyclic aromatic hydrocarbons in heavy oil, which are widely distributed in gums, aromatics and asphaltenes. Polycyclic aromatic hydrocarbons with condensation properties will form coke precursors through condensation reaction, and the limitation of dissolution and diffusion will lead to further polymerization between coke precursors to form residual coke. This makes the utilization rate of heavy oil greatly reduced. Therefore, the dissolution of polycyclic aromatic hydrocarbons is one of the keys to heavy oil upgrading. Nowadays, molecular simulation technology has been successfully applied to supercritical fluids, which plays a good role in the study of high temperature and high pressure fluids. Therefore, in this paper, molecular dynamics simulations were used to study the dissolution behavior of PAHs and PAH mixtures, solvent-solute interactions and solute-solute interactions to reveal the dissolution mechanism in the presence supercritical cyclohexane.