分级多孔HPW/TiO_2催化剂的合成及其氧化脱硫性能

Synthesis of HPW/TiO_2 catalyst and its oxidative desulfurization performance

以阳离子表面活性剂(CTAB)为介孔模板,单分散聚苯乙烯微球(PS)为大孔模板,合成了一系列分级孔磷钨酸(HPW)/TiO_2复合材料,并将其用于燃油深度氧化脱硫。采用X-射线衍射、氮气吸脱附、扫描电镜、红外光谱及紫外光谱等技术对催化剂的结构及形貌进行表征。结果表明,该催化剂具有无序大孔、有序介孔的结构,Keggin型结构HPW高度分散在TiO_2基质中。在优化的反应条件下,该催化剂对苯并噻吩(BT)、二苯并噻吩(DBT)、4,6-二甲基二苯并噻吩(4,6-DMDBT)的脱除率分别达到100%、82%和86%。由于该催化剂的分级孔结构缩短了介孔的传输距离,同时催化剂的高比表面积使得更多的活性中心位点暴露,因此提高了催化剂的催化氧化脱硫性能。此外催化剂循环使用5次后性能仅稍微降低。

A series of hierarchical porous phosphotungstic acid/TiO2（ HPW/TiO2） composite materials are synthesized successfully by dual template method using cationic surfactant（ CATB） as mesoporous template and monodisperse polystyrene microsphere（ PS） as macroporous template.The as-synthesized HPW/TiO2 composite materials are used in the deep oxidative desulfurization for fuel oil. The structure and morphology of HPW/TiO2 catalysts are characterized by X-ray diffraction,nitrogen adsorption-desorption isotherms,scanning electron microscope,Fourier transform infrared spectra and diffuse reflectance UV-Vis spectra. The results indicate that the HPW/TiO2 catalysts possess a structure of disordered macropores and ordered mesopores,with Keggin type HPW highly dispersing in the TiO2 matrix.Under the optimized reaction conditions,the removal rates of benzothiophene（ BT）,dibenzothiophene（ DBT） and 4,6-dimethyldibenzothiophene（ 4,6-DMDBT） over the prepared catalyst are 100%,82% and 86%,respectively.Because the hierarchical porous structure of the catalyst reduces the transmission distance of mesoporous and the high specific surface area of catalyst provides more accessible active central sites,the catalytic performance of hierarchical porous catalyst is therefore improved.In addition,the catalyst has excellent cycle performance,there is no obvious performance reduce even after 5 cycles.