Behavior of NiMo/SBA-15 catalysts prepared with citric acid in simultaneous hydrodesulfurization of dibenzothiophene and 4,6-dimethyldibenzothiophene

Hydrodesulfurization of Dibenzothiophene: A Machine Learning Approach

The hydrodesulfurization (HDS) process is widely used in the industry to eliminate sulfur compounds from fuels. However, removing dibenzothiophene (DBT) and its derivatives is a challenge. Here, the key aspects that affect the efficiency of catalysts in the HDS of DBT were investigated using machine learning (ML) algorithms. The conversion of DBT and selectivity was estimated by applying Lasso, Ridge, and Random Forest regression techniques. For the estimation of conversion of DBT, Random Forest and Lasso offer adequate predictions. At the same time, regularized regressions have similar outcomes, which are suitable for selectivity estimations. According to the regression coefficient, the structural parameters are essential predictors for selectivity, highlighting the pore size, and slab length. These properties can connect with aspects like the availability of active sites. The insights gained through ML techniques about the HDS catalysts agree with the interpretations of previous experimental reports.

Constructing superior Co-Mo HDS catalyst from a crystalline precursor separated from the impregnating solution

In this paper, a Co tetra-capped Keggin crystalline Co4Mo12 was separated from the impregnating solution through the self-assembly strategy. The crystalline Co4Mo12 was structurally characterized and used as a molecular...

Ni-modified MoS2 nanoflake arrays with stepped sites on carbon nanotubes for efficient hydrodesulfurization of coal-to-liquid fuel

Carbon nanotube (CNT)-supported Ni-modified MoS₂ catalysts with ultra-high loading were synthesized with the assistance of citric acid. The morphology of the nanoflake arrays could be controlled to give abundant stepped sites, which favored the hydrogenation desulfurization pathway of dibenzothiophene. The catalyst exhibited excellent performance and stability for hydrodesulfurization of model oil and coal-to-liquid fuel.

Effect of Mono-, Di-, and Triethylene Glycol on the Activity of Phosphate-Doped NiMo/Al2O3 Hydrotreating Catalysts

The effect of glycols on the catalytic properties of phosphate-doped NiMo/Al2O3 catalysts in the hydrotreating of straight-run gas oil (SRGO) was studied. The NiMo(P)/Al2O3 catalysts were prepared using ethylene glycol (EG), diethylene glycol (DEG), and triethylene glycol (TEG) as additives. The organic agent was introduced into the aqueous impregnation solution obtained by the dissolving of MoO3 in H3PO4 solution, followed by Ni(OH)2 addition. The Raman and UV–Vis studies show that the impregnation solution contains diphosphopentamolybdate HxP2Mo5O23(6−x)− and Ni(H2O)62+, and that these ions are not affected by the presence of glycols. When the impregnation solution comes in contact with the γ-Al2O3 surface, HxP2Mo5O23(6−x)− is decomposed completely. The catalysts were characterized by Raman spectroscopy, low-temperature N2 adsorption, X-ray photoelectron spectroscopy, and transmission electron microscopy. It is shown that the sulfide catalysts prepared with glycols display higher activity in the hydrotreating of straight-run gas oil than the NiMoP/Al2O3 catalyst prepared without the additive. The hydrodesulfurization and hydrodenitrogenation activities depend on the glycol type and are decreased in the following order: NiMoP-DEG/Al2O3 > NiMoP-EG/Al2O3 > NiMoP-TEG/Al2O3 > NiMoP/Al2O3. The higher activity of NiMoP-DEG/Al2O3 can be explained with the higher dispersion of molybdenum on the surface of the catalyst in the sulfide state.

Recent Insights in Transition Metal Sulfide Hydrodesulfurization Catalysts for the Production of Ultra Low Sulfur Diesel: A Short Review

The literature from the past few years dealing with hydrodesulfurization catalysts to deeply remove the sulfur-containing compounds in fuels is reviewed in this communication. We focus on the typical transition metal sulfides (TMS) Ni/Co-promoted Mo, W-based bi- and tri-metallic catalysts for selective removal of sulfur from typical refractory compounds. This review is separated into three very specific topics of the catalysts to produce ultra-low sulfur diesel. The first issue is the supported catalysts; the second, the self-supported or unsupported catalysts and finally, a brief discussion about the theoretical studies. We also inspect some details about the effect of support, the use of organic and inorganic additives and aspects related to the preparation of unsupported catalysts. We discuss some hot topics and details of the unsupported catalyst preparation that could influence the sulfur removal capacity of specific systems. Parameters such as surface acidity, dispersion, morphological changes of the active phases, and the promotion effect are the common factors discussed in the vast majority of present-day research. We conclude from this review that hydrodesulfurization performance of TMS catalysts supported or unsupported may be improved by using new methodologies, both experimental and theoretical, to fulfill the societal needs of ultra-low sulfur fuels, which more stringent future regulations will require.

Intrinsic role of pH in altering catalyst properties of NiMoP over alumino-silicate for the vapour phase hydrodeoxygenation of methyl heptanoate

Ni₂P, MoP, and NiMoP supported on MAS (10) were successfully prepared using acid and base regulators. The intrinsic role of pH and synergic factors has altered the physicochemical properties of the catalysts, which are responsible for HDO activity.

A new approach to construct a hydrodesulfurization catalyst from a crystalline precursor: ligand-induced self-assembly, sulfidation and hydrodesulfurization

This paper proposes a new approach for investigating the mechanism of the formation of the active phase of a hydrodesulfurization (HDS) catalyst via crystalline polyoxometalate (POM) precursors.

Synthesis of ZSM-5/KIT-6 with a tunable pore structure and its catalytic application in the hydrodesulfurization of dibenzothiophene and diesel oil

Porous support materials were prepared by assembling primary and secondary ZSM-5 structural units into a well-ordered mesoporous framework. The materials possessed both ZSM-5 microporous building units and mesoporous structure were used as supports for the preparation of hydrodesulfurization (HDS) catalysts. The materials and their corresponding catalysts were characterized by XRD, FTIR, ²⁷Al MAS NMR, TEM, N₂ adsorption–desorption, Py-FTIR, H₂-TPR, Raman, and HRTEM techniques. The pore structures of the composite materials were modulated by adjusting the molar ratio of butanol/P123 (BuOH/P123) and then, the influences of BuOH/P123 on the catalytic performance in the HDS of dibenzothiophene (DBT) and diesel oil were systematically studied. The results showed that butanol has a big influence on the structure of the micro–mesoporous material, whereby different micro–mesoporous structures, such as the p6mm hexagonal structure or Ia3̄d cubic structure, were formed with different butanol addition amounts. The composite ZK-3 (BuOH/P123 = 100) possessed the best surface area and pore structure. Therefore, the NiMo/ZK-3 catalyst showed the highest catalytic activity in the HDS of DBT with a BP selectivity of 72.1% due to its excellent textural property, moderate MSI, relatively high B/L ratios, and highly dispersed NiMoS active phases. Moreover, the NiMo/AZK-3 catalyst exhibited excellent catalytic performance in the HDS of diesel oil.

Porous material with tunable pore structure ZSM-5/KIT-6 was prepared by adjusting the addition amount of n-butanol. NiMo/ZK-3 and NiMo/AZK-3 catalysts exhibit good catalytic performances in the HDS of DBT and diesel oil, respectively.

Effect of 2,6-Bis-(1-hydroxy-1,1-diphenyl-methyl) Pyridine as Organic Additive in Sulfide NiMoP/γ-Al₂O₃ Catalyst for Hydrodesulfurization of Straight-Run Gas Oil

The effect of 2,6-bis-(1-hydroxy-1,1-diphenyl-methyl) pyridine (BDPHP) in the preparation of NiMoP/γ-Al₂O₃ catalysts have been investigated in the hydrodesulfurization (HDS) of straight-run gas oil. The γ-Al₂O₃ support was modified by surface impregnation of a solution of BDPHP to afford BDPHP/Ni molar ratios (0.5 and 1.0) in the final composition. The highest activity for NiMoP materials was found when the molar ratio of BDPHP/Ni was of 0.5. X-ray diffraction (XRD) results revealed that NiMoP (0.5) showed better dispersion of MoO₃ than the NiMoP (1.0). Fourier transform infrared spectroscopy (FT-IR) results indicated that the organic additive interacts with the γ-Al₂O₃ surface and therefore discards the presence of Mo or Ni complexes. Raman spectroscopy suggested a high Raman ratio for the NiMoP (0.5) sample. The increment of the Mo=O species is related to a major availability of Mo species in the formation of MoS₂. The temperature programmed reduction (TPR) results showed that the NiMoP (0.5) displayed moderate metal–support interaction. Likewise, X-ray photoelectron spectroscopy (XPS) exhibited higher sulfurization degree for NiMoP (0.5) compared with NiMoP (1.0). The increment of the MoO₃ dispersion, the moderate metal–support interaction, the increase of sulfurization degree and the increment of Mo=O species provoked by the BDPHP incorporation resulted in a higher gas oil HDS activity.

One pot synthesis of NiMo–Al2O3 catalysts by solvent-free solid-state method for hydrodesulfurization

A simple and solvent-free solid-state method was used to prepare NiMo–Al₂O₃ hydrodesulfurization (HDS) catalysts using Ni(NO₃)₂·6H₂O, (NH₄)₆Mo₇O₂₄·4H₂O, and AlCl₃·6H₂O as the solid raw materials and polyethylene glycol (PEG) as an additive.

Synthesis of micro-mesoporous materials ZSM-5/FDU-12 and the performance of dibenzothiophene hydrodesulfurization

The micro-mesoporous materials ZF-x (ZSM-5-FDU-12, x = SiO₂/Al₂O₃) with different molar ratios of SiO₂/Al₂O₃ were synthesized by an in situ nano-assembly method with the ZSM-5 precursor serving as the silica source.