具有π-π吸附功能阳离子交换树脂的烷基化催化精馏脱硫新工艺

Based the characteristics of large π bond with a double-sided three-dimensional for graphene,the one side can form π- interact with catio ion exchange resin to get a stable complex with a cationic structure and enhance its ion exchange capacity; the other side can form π-π binding by adsorption with sulfur components of gasoline. This kind of new catalyst can increase the exchange capacity of resin, to improve the catalytic activity and selectivity of alkylation. And fothermore, by introducing the operation of alkylation catalytic distillation, the polymerization side reaction of olefin can be limtted, thus bringing about energy conservation and high efficiency in alkylation desulfurization of gasoline..The change in the electron structure of graphene before and after adsorption of thionphenic sulfur will be analyzed with quantum chemistry method. In addition, experiments will be carried out to investigate the relationship between the protonation of alkene to carbonium ion and the acidity of catalysts. The validity of catalytic distillation will also be testified. The key science problems of kinetic controlling mechanisms for the alkylation and olefin polymerization in the complex reaction systems with modified cation exchange resin by graphene will be solved; the thermodynamic nature of bifurcation and multi-stability in the catalytic distillation will also be revealed by the investigation of excess entropy production derived from entropy flow and entropy production..Accordingly, high desulfurization efficiencies and a low decrease in octane number of gasoline can be achieved with a complete novel desulfurization process, if this project would be put into effect. It will also lay theoretical and technological foundations of the treatment of mobile pollutant source, and offer new ideas of investigating complex reaction systems in chemical engineering.

基于石墨烯大π键具有立体双面性的特点，使其中一面与阳离子交换树脂通过π-离子相互作用形成结构稳定的复合体并增强其离子交换容量；另一面与油品中含硫组分通过π-π吸附结合，从而强化树脂催化剂对含硫组分的选择性吸附，提高烷基化反应的活性与选择性。进而通过催化精馏操作，进一步抑制烯烃聚合副反应，实现整个烷基化脱硫过程的节能与高效。.通过量子化学计算、实验探讨、系统分析等手段，研究石墨烯吸附噻吩前后的电子结构变化；分析烯烃质子化生成正碳离子的能力与催化剂酸强度的关系；证实催化精馏过程的有效性。着重解决石墨烯改性离子交换树脂上，烷基化与烯烃聚合共存的复杂反应体系的动力学调控机制，以及如何根据烷基化催化精馏过程的熵流、熵产及超熵产生特点，揭示系统的分岔与多稳态现象的热力学本质等关键科学问题。.本项目将开发特色鲜明的油品脱硫新工艺，为移动源污染源治理及化学工程领域复杂系统的研究提供新的思路。

我国汽油中催化裂化汽油约占80%，其中噻吩类含硫组分含量约占总硫含量的60%以上。因此，对于油品中噻吩类含硫组分的脱除，已成为我国生产清洁燃油的关键。烷基化脱硫工艺因具有脱硫效率高、操作条件温和及辛烷值损失小等优点，备受研究者关注。在联合基金的支持下，本项目主要进行了新型烷基化脱硫催化剂的设计制备以及反应精馏的操作的引入研究，探讨了反应产物的调控和整个过程的强化科学策略。.首先使用理论计算和吸附实验结合的方法研究石墨烯和噻吩类含硫物π-π相互作用的本质。结果表明，还原程度越高的石墨烯对二苯并噻吩（DBT）的饱和吸附容量越大。色散力在DBT和石墨烯之间π-π相互作用占主导地位，从而为石墨烯改性固体酸催化剂提供理论支持。然后制备石墨烯改性介孔SiO2，浸渍负载杂多酸，得到石墨烯改性SiO2负载杂多酸催化剂，用于烷基化脱硫研究。石墨烯改性SiO2负载杂多酸催化剂具有比未改性催化剂更高的烷基化脱硫活性。3-甲基噻吩吸附实验结果显示石墨烯改性SiO2具有更高的硫吸附容量，同时DFT计算表明噻吩和烯烃在石墨烯表面具有更高的吸附能。因此使用石墨烯改性后可以有效吸附噻吩类含硫化合物，从而提高噻吩硫在催化剂活性位点附近的浓度，提高催化剂的烷基化脱硫效率。此外，石墨烯改性强酸性阳离子交换树脂，也可达到同样功效。.为了进一步有效抑制烯烃聚合副反应发生，采用反应精馏进行烷基化脱硫反应动力学的调控。首先建立FCC汽油烷基化脱硫反应精馏的严格计算模型，通过与实验数据的对比证实平衡级模型可以较好地描述该过程。然后对反应精馏塔的设计变量和操作变量进行灵敏度分析，研究各变量对脱硫效率及烯烃自聚转化率的影响，得到优化的反应精馏塔参数。同时利用灵敏度分析对催化精馏装置内多稳态行为进行研究，结果显示，反应精馏塔均能保持稳定运行，无分叉现象出现。主要因为硫含量和烯烃自聚量较小，同时热效应较低，烷基化反应对反应精馏塔的运行影响有限。