双助剂修饰铋基复合氧化物选择性光催化氧化FCC汽油深度脱硫

Air pollution, caused by the emission of SOx via the burning of catalytic cracking gasoline (FCC gasoline), is one of the most serious environmental problems in the world. How to remove sulfur has become a technical problems for the relational field. Semiconductor photocatalytic oxidation desulfurization (Photo-Cat-ODS) is one of the newly-developed green-envitonmentally deep desulfurization techniques. However, due to low selectivity of the desulfurization catalysts used the unsaturated hydrocarbons in FCC gasoline can be readily oxidized and result in octane value loss of FCC gasoline thereby decrease the quality of petroleum products. Hence, it has become a research bottleneck for the Photo-Cat-ODS. Therefore, design and construct the efficient photocatalyst with high selectivity become one of the key scientific problems of Photo-Cat-ODS technique. In the present project, based on a series of mesoporous Bi-based composite oxides, some advanced strategies that can change physical-chemical property of Bi-based composite materials such as element doping, narrow-band-gap semiconductor and noble metal quantum quantum dots(QDs) deposition and surface modification, as well as coupling with semiconductor nanojunctions, will be employed to modulate the band structure, and improve the selectivity of Photo-Cat-ODS. Thus, Bi-based di-cocatalysts decorated ternary photocatalysts will be obtained and used in application of visible and near infrared (Vis-NIR) light driven Photo-Cat-ODS with high selectivity. Also, based on the systematic characterization and investigation of desulfurization reaction, the project will further explore the pattern of adsorption and conversion for the reactants on the surface of catalyst. At the same time, the intermediates will be also studied in detail. Meanwhile, the structure-activity relationship between catalytic performance, selectivity and composition, structure will be established for the photocatalytic desulfurization. Furthermore, this project will also provide the scientific basis for the applications of photocatlytic oxidative desulfurization technology in the production process of clean fuel oil.

催化裂化(FCC)汽油燃烧释放的硫氧化物对大气造成严重污染，如何除去硫元素是相关学科面临的难题。半导体光催化氧化是一种绿色环保的脱硫技术，但存在催化剂的选择性低、FCC汽油中不饱和烃易被氧化而致辛烷值损失的技术瓶颈。因此，构建高选择性光催化剂成为光催化氧化脱硫工艺的关键科学问题之一。本项目拟在多孔Bi基复合氧化物的基础上，通过元素掺杂、窄带隙半导体耦合和贵金属量子点表面组装等调控能带结构，在拓宽催化剂的光响应范围的同时提高光催化反应的选择性，获得具有氧化与还原助剂修饰的三元催化剂，用于实现FCC汽油在可见-近红外光激发下的选择性深度脱硫。通过对Bi基复合氧化物的系统表征和对脱硫反应的深入研究，探索含FCC汽油中的含硫化合物在催化剂表面的吸附转化和中间物种耦合反应的机制，揭示三元催化剂的组成、结构和选择性之间的“构效关系”，为光催化氧化脱硫技术在清洁燃油生产过程中的实际应用提供科学依据。

光催化氧化是一种绿色环保的脱硫技术，但存在催化剂的选择性低、FCC汽油中不饱和烃易被氧化而致辛烷值损失的技术瓶颈。因此，构建高选择性光催化剂成为光催化氧化脱硫工艺的关键科学问题之一。本项目通过Bi基复合光催化材料的组成、形貌、结构和能带设计，实现对其光催化脱硫性能的精准调控。提出了构筑形貌规整、孔结构丰富的二维、三维Bi基催化材料的新思路；建立了基于电子结构调控（掺杂）、表/界面改性（贵金属沉积、氧空位锚定）、异质结构建（p-n型、Z-型、S-型）等策略，设计Bi基催化剂能带结构、优化其光能利用率和载流子的分离/迁移效率，实现催化剂的性能精准调控，在拓宽催化剂的光响应范围的同时提高光催化反应的选择性，成功获得具有氧化、还原助剂修饰的Bi基催化剂催化剂，用于实现FCC汽油在可见光激发下的选择性深度脱硫，明晰了其光催化活性和结构之间的“构效关系”；所得三元CdS/Ag/Bi2MoO6光催化剂对氧化DBT脱硫活性是纯Bi2MoO6的6倍；La、F共掺Bi2MoO6对DBT的光催化氧化脱硫率是纯Bi2MoO6的6.5倍；构筑了系列“核-壳”结构的磁性Bi基催化剂并设计了配套的回收装置，为该类催化材料的实际应用奠定了基础；可见光下开发的磁性Fe3O4@ SiO2/Bi2S3/Bi2WO6催化剂，具有优越的模拟FCC汽油脱硫活性，可见光照射2h，可使用硫含量从500μg/g降低至1μg/g，且催化剂的重复使用性能良好。上述工作对推动Bi基半导体催化材料的实际应用具有重要意义。