新型高选择性光催化吸附耦合技术及其燃油吸附脱硫机理

Ultra-deep desulfurization has attract widespread attention from both petroleum industry and scientific community due to its environmental concerns, and ultra-clean fuel required applications, i.e. fuel cells. The major challenges for ultra-deep desulfurization of diesel fuel include: (a) the steric hindrance effect of alkylated organosulfur compounds；(b) the competitive adsorption between the trace amount of organosulfur compounds and relatively large amount of polyaromatics and others in diesel. To overcome the above barriers, we propose a novel approach of photocatalysis-assisted selective adsorption for ultra-deep desulfurization of diesel fuel, which essentially requires a photocatalyst to chemically transform the organosulfur compounds to the corresponding polar sulfones induced by the light-sensitive alkylated polycyclic aromatic hydrocarbons in fuels, and the sulfones can subsequently be removed by selective adsorption over functional adsorbents.The proposed work will focus on (a) fundamentally understanding of the structure-performance relationships between the composition, textural peoperties,light wavelength and intensity of the doped TiO2 photocatalyst structure and peroxide generation kinetics, between the textural peoperties and surface chemistry of the functional adsorbents and adsorption capacity and selectivity of sulfoxides or sulfones, and further build the mechanistic photocatalysis-assisted adsorption models；(b)mechanistic design of doped TiO2 metal oxides photocatalysts with high peroxide generation rate in fuel, and functional adsorbents with high adsorption capacity and selectivity of sulfoxides and sulfones. Develop a highly efficient separation process based on the new photocatalysis-assisted adsorption for ultra-deep desulfurization to achieve ultra-clean fuels (<1 ppmw-S) with high desulfurization capacity. The development of the proposed photocatalysis-assisted selective adsorption will open a new window for the practical applications of ultra-deep desulfurization for ultra-clean fuels. Meanwhile, it will enrich the adsorption theories and generate new interdiciplinary adsorption-based science for liquid-phase desulfurization.

针对吸附法柴油深度脱硫中，由于部分硫化物存在空间位阻效应和燃油其它组份的竞争吸附导致难于深度脱硫这两大关键难题，本项目提出研究新型高选择性光催化吸附耦合技术及脱硫机理。主要研究利用光催化诱导燃油中烷基多环芳烃生成芳烃过氧化物，其选择性地将柴油中有机硫氧化为较强极性的砜类化合物，研制高效极性吸附剂从柴油中选择性地将其脱除而制得超清洁柴油。本项目将从理论层面上，研究掺杂型TiO2光催化剂的组成、孔隙结构以及光的波长和强度对芳烃过氧化物产生速率的影响规律；研究多孔吸附材料的孔隙结构和表面化学对砜类化合物吸附的影响规律；研究光催化/吸附耦合技术深度脱硫机理和模型；从技术层面上，研制出高芳烃过氧化物产生速率的掺杂型TiO2光催化剂和高脱砜容量吸附剂，建立基于高选择性的光催化吸附耦合技术的低能耗高效燃油深度脱硫过程。该研究成果将为超清洁燃油生产提供新思路、新理论和技术基础，具有重要科学意义和应用前景。

针对吸附法柴油深度脱硫中，由于部分硫化物存在空间位阻效应和燃油其它组份的竞争吸附导致难于深度脱硫这两大关键难题，研究了新型高选择性光催化吸附耦合技术及脱硫机理。主要研究利用光催化诱导燃油中烷基多环芳烃生成芳烃过氧化物，其选择性地将柴油中有机硫氧化为较强极性的砜类化合物，研制高效极性吸附剂从柴油中选择性地将其脱除而制得超清洁柴油。主要研究进展包括：（1）开发了基于TiO2-CeO2/MCM-48催化吸附材料的柴油光催化吸附耦合深度脱硫过程。制备了新型的TiO2-CeO2/MCM-48催化吸附材料，其可将真实柴油中的有机硫脱除到<1ppm获得超清洁柴油，且吸附量可高达95-ml柴油/g-材料；揭示了TiO2-CeO2/MCM-48催化吸附材料的载体孔隙结构和载体表面化学对其脱硫容量的影响规律，建立了光催化氧化脱硫机理和模型；提出两步法光催化氧化吸附脱硫新工艺，可在常温常压无氢气消耗的条件下，将燃油中的硫含量脱除至<1 ppm获超清洁柴油。（2）开发了基于TiO2/SiO2的新型一步法紫外光催化氧化和吸附耦合深度脱硫过程。以空气为氧化剂和紫外光辐射下，通过TiO2/SiO2双功能催化吸附材料实现了一步法光催化氧化吸附耦合深度脱硫，在低硫浓度（15ppm）下的硫容高达5.12 mg/g，脱硫选择性达325.5；在该耦合体系中，高度分散的TiO2作为氧化催化位，SiO2作为主要的硫砜吸附位，通过两种活性位的协同作用来实现高选择性深度脱硫；建立了基于光催化吸附耦合技术的低能耗高效燃油深度脱硫过程。（3）开发了基于BiVO4/C3N4@SiO2的新型一步法可见光光催化氧化吸附耦合深度脱硫过程。以过氧化氢二丙苯为氧化剂和可见光辐射下，通过BiVO4/C3N4@SiO2实现可见光光催化氧化吸附耦合深度脱硫，硫容高达7.2 mg/g；BiVO4/C3N4@SiO2的高可见光光催化活性主要是因为BiVO4/C3N4的有效电荷分离作用和小颗粒BiVO4的高光催化活性；同时发现有趣的是：在体系中同步通入空气大幅促进了耦合脱硫的动力学，这主要是因为空气和过氧化氢二丙苯的共同作用加速了ROO活性氧的生成。（4）采用实验/模拟结合的方法研究阐明了基于金属有机骨架材料和碳材料吸附剂的燃油吸附脱硫脱氮机理。该研究成果为超清洁燃油生产提供新思路、新理论和技术基础，具有重要科学意义和应用前景。