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A series of NiMo/FDU-12 catalysts with tunable pore diameters and mesostructures have been controllably synthesized by adjusting the synthetic hydrothermal temperature and applied for the hydrodesulfurization of dibenzothiophene and its derivative. The state-of-the-art electron tomography revealed that the pore sizes of FDU-12 supports were enlarged with the increase in the hydrothermal temperature and the mesostructures were transformed from ordered cage-type pores to locally disordered channels. Meanwhile, the MoS2 morphology altered from small straight bar to semibending arc to spherical shape and finally to larger straight bar with the change of support structures. Among them, FDU-12 hydrothermally treated at 150 °C possessed appropriate pore diameter and connected pore structure and was favorable for the formation of highly active MoS2 with curved morphology; thus, its corresponding catalyst exhibited the best HDS activity. Furthermore, it was indicated that the isomerization pathway could be significantly improved for HDS of 4,6-dimethyldibenzothiophene after the addition of aluminum, which was expected to be applied to the removal of the macromolecular sulfur compounds. Our study sheds lights on the relationship between support effect, active sites morphology and HDS performance, and also provides a guidance for the development of highly active HDS catalysts. [ABSTRACT FROM AUTHOR]

Abstract: A series of mesoporous sieves with different pore diameters and structures have been controllably synthesized by adding variable amounts of swelling agent 1,3,5-trimethylbenzene in the preparation process for SBA-15. NiMo catalysts supported by mesoporous sieves are prepared by using the newly proposed Mo-based organic–inorganic hybrid nanocrystals as precursors to load Mo and subsequently using wetness impregnation to load Ni. The hydrodesulfurization (HDS) activity of these obtained catalysts is evaluated in a continuously flowing tubular fixed-bed microreactor using 1wt% dibenzothiophene (DBT) in heptane as a model compound. The results show that HDS ratio has gradually increased as the pore diameter of supports is enlarged from 7 to 11nm with the mesostructure keeping an ordered two-dimensional hexagonal symmetry. When the structure is in the intermediate stage of structural transition from ordered hexagonal mesostructure to mesocecullar structure, HDS ratio is decreased dramatically due to the disordered and collapsed structure to block the pore channels. After the mesocecullar structure with three-dimensional open pore channels is formed which is more convenient for the molecular diffusion, HDS ratio has increased again as a result. It is concluded that both the pore size and window size connecting the adjacent pores play an important role in the HDS activity but the window size is of more significant importance, which is the key point for the enhanced catalytic performance. [Copyright &y& Elsevier]