页岩油中苯并噻吩及其衍生物的脱硫机制的理论研究

Benzothiophene and its derivatives are important constituents of the organosulfur compounds in shale oil, and they are difficult to be removed by traditional desulfurization method. The removal of thiophenic compounds has a great significance for effective use of shale oil and environment protection. The selection of effective desulfurization method and the chemical kinetic model for desulfurization is critical for the effective use of shale oil. This project is to investigate benzothiophene and dibenzothiophene as model compounds, with the focus on the oxidative desulfurization and CO2 supercritical extraction desulfurization. High-level quantum chemical methods will be employed to study the electronic structures of sulfur-containing compounds, predicting the possible position for desulfurization and the reactivity of oxidation. The relationship between the microstructure and reactivity will be built by comparing different substituent groups and oxidation reactivity. Meanwhile, the energetic reaction routes for the reactions of the thiophenic compounds with oxygen molecules will be calculated, the rate constants and rate-controlling step will be determined. Molecular simulation will be used to discuss the interaction in supercritical CO2 — thiophenic compounds mixed system. The phase behavior of these systems will be analyzed, and the effects of temperature and pressure will be studied. Finally, the effective desulfurization mechanisms will be established theoretically to shed new light on the good use of shale oil.

苯并噻吩及其衍生物是页岩油中有机硫的重要组成部分, 且脱除困难，其脱除对于高效利用页岩油和环境保护都具有重大意义。选择有效脱硫方法和建立脱硫的化学动力学模型是高效清洁利用页岩油的关键。本项目拟选取页岩油中以苯并噻吩、二苯并噻吩及其衍生物为含硫模型，重点考察氧化脱硫和超临界CO2萃取脱硫的微观反应机理。应用高水平的量子化学计算方法，通过含硫化合物电子结构计算预测弱键位置和脱硫的可能性，比较不同取代基对氧化活性的影响，获得此类含硫化合物的构效关系。同时，计算不同温度、压力下的反应速率和分支比，建立氧化脱硫的动力学模型。结合分子模拟，探讨苯并噻吩及其衍生物在超临界CO2中的溶解性及扩散性等，揭示超临界CO2与硫化物之间的复杂相互作用。通过分析各体系的相行为，考察温度和压力对流体微观结构的影响。最终建立有效脱硫的理论机制，为更好的开发利用页岩油奠定理论基础。

苯并噻吩及其衍生物是页岩油中有机硫的重要组成部分，且脱硫困难。为了研究这一类代表性较难脱除的有机硫的脱硫反应机理，我们采用量子化学方法系统地研究了苯并噻吩及其衍生物（二苯并噻吩、4,6-二甲基二苯并噻吩）与单三态氧气反应的电子结构、热力学稳定性以及反应活性等。我们的研究结果表明，基态（三重态）的氧气直接氧化苯并噻吩及其衍生物分子比较困难，而与激发态（单重态）氧气容易发生光化学环加成反应。单态氧分子可以直接进攻噻吩环上的两个碳原子，也可以选择进攻硫原子，不同体系中这两种反应进攻方式的难易程度也不同。氧化生成亚砜及砜类化合物, 最终降解生成联苯系列化合物和乙酰化产物。此外，我们还采用Monte Carlo方法探讨了苯并噻吩与超临界CO2之间的复杂相互作用。通过对苯并噻吩-超临界CO2混合体系的结构分析可知苯并噻吩在二氧化碳周围有明显的聚集。由于实验数据的缺乏，混合体系的力场参数及相互作用有待进一步优化和深入分析。