Extensive efforts have been devoted to developing desulfurization catalysts to effectively remove sulfur from fuel. Active phase metals including cobalt, nickel, molybdenum, and tungsten have been extensively used in industry for hydrotreating/hydrodesulfurization catalysts for over 50 years. However, while it is desirable to use inexpensive materials to do the same job, it is a grand challenge. Herein, we report a Fe-based sulfide catalyst that is tuned by zinc with high activity for HDS, which shows an industrial application potential to replace industrial Mo-based catalysts. With an optimal configuration that has a Fe:Zn ratio close to 1:1, the reaction rate constants of the dibenzothiophene (DBT) and 4,6-dimethydibenzothiophene (4,6-DMDBT) HDS are increased by 9.2 and 17.4 times, respectively, in comparison with the sums of those on the monoiron and zinc sulfides. HDS activity for the sterically hindered 4,6-DMDBT on the FeZn sulfide catalyst is even close to that of Co-MoS2. The experimental results indicate that the addition of Zn greatly modifies the electronic properties of iron sulfide by transferring electrons from Zn to Fe, which tunes the d band center to modulate the adsorption behavior of DBT and 4,6-DMDBT. In combination with theoretical calculations, our experiments show that the addition of Zn dramatically tunes the formation of sulfur vacancies. We propose that the formation of sulfur vacancies is the critical factor for designing highly efficient Fe-based sulfide catalysts. This study provides the design principle of low-cost desulfurization catalysts for industrial refinery applications.

Appropriate electronic structure is vital to promote the catalytic performance of active species. In this work, TiO2–x was employed to regulate active Fe species to the electron-rich state, causing remarkable synergetic effects in which the sulfur removal rates of Fe-based catalysts were increased by 10–40% and reaction rate constants were also increased by around 100% (pure Fe-based catalysts) and 30% (Fe-Zn bimetallic catalysts). The results of characterization and DFT calculations show that the strong electron-donating effect of TiO2–x on Fe species can promote the dispersion of Fe species and weaken the Fe–O and Fe–S/FeZn–S bonds, resulting in the increases in sulfidation degrees by around 3.5% and enrichments of coordinatively unsaturated sites or sulfur vacancies. In addition, weaker Al–OH peaks caused by TiO2 can also facilitate the increase in sulfidation degrees of Fe-based catalysts. Furthermore, hydrodesulfurization/direct desulfurization ratios are decreased by adding TiO2–x , attributed to the electron-rich Fe species that makes C–S bonds and α/β-H more vulnerable to attacks. Slight changes in acidity caused by TiO2–x have little effect on the catalytic performances of Fe-based catalysts. This work lays a solid foundation for industrial application of eco-friendly and economical Fe-based catalysts in the HDS field.

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A novel organic template-free strategy for generating mesoporosity in Y zeolites is reported. It is revealed that Fe(3+) functioned as unstable sites in the Fe-NaY zeolite, which promotes deferrization-dealumination, leading to enhanced formation of intra-crystalline mesopores as well as desirable interconnectivity. The mesopore-enriched zeolite exhibits a remarkable ability in conversion of the bulky substrate.

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In this study mesoporous zeolite Y (USY-F-AT) was prepared by fluorine−alkaline combined treatment method. The properties of USY-F-AT were characterized by XRD, N 2 physisorption, NH 3 -TPD, XPS, and TEM. USY-F-AT provided greater mesopore volume and surface area than conventional USY. NH 3 -TPD showed the USY-F-AT has many more acid sites and stronger acid strength compared with USY. Ni and Mo were impregnated into USY and USY-F-AT to form catalysts NiMo/(Al 2 O 3 + USY) and NiMo/(Al 2 O 3 + USY-F-AT), respectively. The hydrogenation activity and cracking ability of catalysts NiMo/ (Al 2 O 3 + USY) and NiMo/(Al 2 O 3 + USY-F-AT) were studied by hydrocracking reaction using naphthalene as model compound. The results showed that catalyst NiMo/(Al 2 O 3 + USY-F-AT) exhibited similar hydrogenation activity but much higher ring-opening ability in comparison with catalyst NiMo/(Al 2 O 3 + USY).

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