Abstract
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.
Highlights
Nowadays, the demand of low-sulfur, high-quality transportation fuels is growing rapidly by reason of the necessity to solve pollution problems induced by S Ox emissionsHandling Editor: Jian LiuEdited by Xiu-Qiu PengElectronic supplementary material The online version of this article contains supplementary material, which is available to authorized users.Support is one of the most important parts for HDS catalyst, which plays a vital role in bearing active components, improving their dispersion as well as providing a space for the catalytic reactions
26.0 17.6 39.2 a BET surface area b Pore volume c Pore size obtained by adsorption branch d Entrance size obtained by desorption branch e Unit cell parameter, the value is calculated by a0 = d111
The results indicate that the supports (F-100 and F-130) obtained at lower hydrothermal temperature have relatively independent cage-type holes with small connection in between, while the shape of cavity is relatively regular
Summary
The demand of low-sulfur, high-quality transportation fuels is growing rapidly by reason of the necessity to solve pollution problems induced by S Ox emissions. The results showed that such supports favored the formation of type II active phases with good dispersion which exhibited higher HDS activity than γ-Al2O3 supported catalysts Both the pore diameter and structure of catalyst supports showed important effects on the HDS activity (Zhou et al 2020; Meng et al 2020; Zhang et al 2019). Soni et al (2010) reported that, compared to SBA-15 supported catalyst with a 2D hexagonal structure, NiMo/KIT-6 with a 3D bicontinuous structure exhibited a much higher HDS performance since the 3D mesostructured KIT-6 could afford a better dispersion of active species and faster diffusion of reactants and products. The properties of corresponding NiMo supported catalysts are comprehensively characterized, and the effects of the pore size, mesostructure and aluminum modification on the MoS2 morphology and their catalytic performance for HDS are systematically explored. It is found that the morphology of the M oS2 active site changes with the change of the support structure, further affecting the HDS performance
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