离子液体模板构筑钒氧化物/三维多孔氮化碳催化氧气氧化柴油脱硫的研究

Deep desulfurization of diesel oil has been turned to be a crucial issue in petroleum refining industry. In this project, we aim to construct VOx /3D porous g-C3N4 catalysts and employ oxygen in air as oxidant for deep removal of 4,6-DMDBT and its derivatives from diesel oil. The 3D porous g-C3N4 is obtained by a supramolecular assembly method, and the vanadium-based ionic liquids are employed as the in-situ templates to load vanadium oxides with different oxidation states on to 3D porous g-C3N4. In this way, an adsorption coupled with oxidative desulfurization system is obtained. In addition, we study the effects of oxidation state of VOx, dispersity, oxygen vacancies, as well as porous structures and specific surface areas of 3D porous g-C3N4 on aerobic catalytic oxidative desulfurization performance, and also carried out to obtain a structure-activity relationship. The recycling performance of the catalyst is also performed to determine the stability, and the catalytic activity over real diesel fuel is also studied. Aerobic oxidative desulfurization mechanism is determined by in situ spectrum characterizations, electron paramagnetic resonance characterization and free radical capture experiments. The catalytic material can combine the catalytic activity of VOx with the adsorption of 3D porous g-C3N4, and the O2 can be readily activated by the synergistic effect. With the development of the project, a novel catalytic oxidative desulfurization system can be developed, and provides experimental and theoretical foundations of deep desulfurization of diesel oil.

柴油深度脱硫是当今炼油工业的重大课题。本项目旨在以钒氧化物/三维多孔氮化碳为催化剂，空气中的O2为氧化剂，深度脱除柴油中4,6-二甲基二苯并噻吩类硫化物。通过超分子组装法构建三维多孔氮化碳，利用钒基离子液体为模板将不同钒氧化态的钒氧化物原位负载到三维多孔氮化碳上，构筑吸附耦合催化氧化脱硫体系。研究钒氧化物的氧化态、分散度、氧缺陷位浓度以及三维多孔氮化碳的孔结构和比表面积等因素对活化O2脱硫效果的影响，关联构效关系。通过对反应后催化剂的再生，考察催化剂的循环使用性能，进一步研究其对真实柴油的脱硫效果。利用原位谱学表征、电子顺磁共振表征结合自由基消除实验，研究本催化体系活化O2脱硫机理。该催化材料将钒氧化物催化氧化脱硫性能与三维多孔氮化碳对硫化物的吸附性能相结合，且两者可以协同活化O2，达到柴油深度脱硫目的。本课题的开展，将开发出一种新型催化氧化脱硫体系，为实现柴油深度脱硫提供实验和理论依据。

柴油中的含硫化合物燃烧后生成的硫氧化物，会造成严重的大气污染，对柴油进行深度脱硫具有重要的研究意义。本课题通过超分子组装法制备了具有三维多孔结构的氮化碳（3D g-C3N4）作载体，用于负载钒基功能化离子液体和不同钒氧化态的钒氧化物（VOx），制备了一系列负载型催化剂，构筑吸附耦合催化氧化脱硫体系。通过FT-IR、XRD、N2吸附-脱附、XPS、SEM和TEM等技术对所合成的材料进行了结构组成和形貌分析，并考察了VOx的负载量和分散度、钒的氧化态、载体的孔结构和比表面积等对负载型催化剂催化氧化脱硫性能的影响。结果表明，所合成的不同氧化态的钒氧化物均具有优异的催化氧化脱硫活性，在适宜的条件下能将模型油中的硫化物降低至10 ppm以下。实验中考察了复合材料催化剂的循环使用性能及对不同含硫底物的脱除效果，通过GC-MS表征、ESR表征和自由基消除实验等对催化氧化脱硫机理进行了探讨。此外，研究中发现，所合成的负载型钒基功能化离子液体也具有良好的催化氧化脱硫活性，通过调控离子液体负载量和反应条件，能够实现深度脱硫目标，且载体的比表面积对复合材料催化性能有较大影响。因此，本课题研究过程中还采用多次热缩聚法制备了具有大比表面积的少层氮化碳作载体，构建能高效催化氧化脱硫的负载型催化材料，实现深度脱硫目的。本课题的开展，开发出了一种新型吸附耦合催化氧化脱硫体系，实现柴油深度脱硫，具有较大的工业应用前景。