稠环芳烃直接加氢的分子模拟研究

Molecular modelling of direct radical hydrogenation on different PAHs molecules

为提高重质油轻质化效率,抑制生焦,需对其中稠环芳烃加氢的具体过程详细探讨。本论文构建了一系列不同芳环数组成的稠环芳烃,以分子模拟为手段从反应机理层面研究稠环芳烃(PAHs)加氢反应过程。采用基于密度泛函理论的DMol^3模块对反应过程进行模拟计算,得到不同稠环芳烃加氢过程的反应热和能垒,通过数据比较探索稠环芳烃按照自由基热反应机理加氢时反应的难易程度。数据分析的结果显示,在自由基足量存在且能与模型化合物有效接触的理想状态下,稠环芳烃分子芳环数、分子饱和度对加氢难易程度影响不大,芳环极易与氢自由基结合,重质油加氢困难并非是因为稠环芳烃与氢自由基直接反应困难造成。

Polyaromatic hydrocarbons （PAHs） in heavy oil limit the efficiency of conversion, and act as coke precursors during hydroprocessing, so it is necessary to investigate the hydrogenation process of PAHs. In this paper, a series of PAHs was constructed as model compounds to investigate their hydrogenation through molecular modeling approach. Through comparison both thermodynamic and dynamic data obtained from modeling calculation, we draw to the conclusion that, with sufficient hydrogen radical to contact with model compounds, the reaction of PAils hydrogenation is neither affected by molecule size, nor their degree of saturation. Hydrogen radical is very easy to react with PAils, and thus the difficulty of heavy oil hydrogenation is not caused by PAHs hydrogenation reaction. Work in this context is in progress.