Abstract
FDU-12 silica with highly ordered face-centered cubic mesoporous structure is developed as support to prepare Mo/FDU-12 catalysts for hydrodesulfurization (HDS) of dibenzothiophene (DBT). A series of Mo/FDU-12 catalysts are synthesized by using incipient wetness impregnation method with different MoO3loadings (6, 8, 10, 12, and 15 wt.%). The objective of this work is to explore the pore confinement effect of FDU-12 mesochannels on the MoS2morphology with various metal loadings. It is found that, as increasing MoO3loadings from 6 to 15 wt.%, the MoS2nanocrystallites transform from monolayer to multilayer and the morphology changes from straight layered to curved and then to ring-like and finally to spherical-like morphology due to the restriction of cage-like pore channels of FDU-12 support. The HDS results show that the catalytic activity increases first and then decreases with the best HDS performance at the MoO3loading of 10 wt.%. In addition, we compared the HDS activity of Mo catalyst supported on FDU-12 with that on the commercialγ-Al2O3and SBA-15; the result exhibits that FDU-12 is superior to the other two supports due to its large pore size and ordered three-dimensional open pore channels.
Highlights
Ordered mesoporous materials with high surface area, large pore volume, ordered pore structure, and good thermal and mechanical stabilities have a broad range of applications in catalysis, adsorption, energy storage, and nanodevices due to their unique physical and chemical properties [1,2,3,4]
When the active phase precursor is incorporated into the pores of the support, it can be inevitably restricted by the pore size and pore structure and, it is interesting to explore the pore confinement effect on the active phases
The results show that the morphology of MoS2 changes from straight layered to curved and to ring-like and spherical-like morphology as increasing MoO3 contents (Scheme 1) owing to the restriction of cage-like pore channels of FDU-12 support and the best HDS activity is found at MoO3 loading of 10 wt.% with curved active phases
Summary
Ordered mesoporous materials with high surface area, large pore volume, ordered pore structure, and good thermal and mechanical stabilities have a broad range of applications in catalysis, adsorption, energy storage, and nanodevices due to their unique physical and chemical properties [1,2,3,4]. The typical 2D mesoporous materials are SBA-15, MCM-41, and so forth [5, 6] and the 3D mesoporous materials usually include MCM-48, SBA-16, KIT-6, and FDU-12 [7, 8], whose property is considered to be superior to the former because the 3D channel is favorable for the mass transfer and diffusion of guest molecules. Among different materials recently as supports for HDS catalysts, the mesoporous silica materials with ordered pore structures such as SBA-15, MCM41, and KIT-6 have attracted widespread attention [11,12,13,14,15]. FDU-12 is a kind of 3D material with a face-centered cubic (Fm-3m) symmetry and its particular property of highly open channel networks makes it possible for faster diffusion of reactants and products during the reaction without pore blockage as happened in MCM-41 and SBA-15 with linear pore channel structure [13]. To the best of our knowledge, there is no report to investigate the pore confinement effect of the cage-like pore structure of FDU-12 on the active phases with the increase of metal loadings and further on the variation of HDS activity
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