Influence of alumina fluoridation on the dispersion and hydrotreating activity of WAl2O3 catalysis

Benitez, A.; Ramirez, Jorge; Espinoza-Vázquez, Araceli; Acosta, D.; Agudo, Antonio

doi:10.1016/0926-860x(95)00177-8

Cited by 37 publications

(11 citation statements)

References 37 publications

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“…The low temperature peak at about 595 C corresponds to the reduction of octahedrally coordinated polymeric tungsten species. 51,52 The high temperature peak at about 768 C can be attributed to the reduction of tetrahedrally coordinated monomeric tungsten species, which are mostly stabilized on the alumina support. 53,54 Because the peak temperatures in H 2 -TPR profiles reflect the metal-support interaction over supported catalysts, 55,56 the similar high and low peak temperatures of catalyst NWF-CFHD to those of catalyst NWF-IM in Fig.…”

Section: Nh 3 -Tpd H 2 -Tpr and Xps Characterizationsmentioning

confidence: 99%

A novel approach for modulating the morphology of supported metal nanoparticles in hydrodesulfurization catalysts

Fan

Xiao

Shi

et al. 2011

Energy Environ. Sci.

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This article proposes a novel cetyltrimethylammonium bromide-and fluorine-assisted hydrothermal deposition method for modulating the morphology of supported metal nanoparticles in NiWF/Al 2 O 3 hydrodesulfurization (HDS) catalysts. The proposed approach significantly promotes the dispersion of supported W species by bridging and anchoring the precursor of W species onto the surface of fluorinated Al 2 O 3 as well as restraining the subsequent aggregation of W species in calcination. The dual effects of the improved dispersion and F-enhanced stacking endow the corresponding catalyst with superior morphology featured by sufficient and accessible Ni-W-S active phases and thereby with a remarkably promoted HDS performance as compared to its counterpart prepared by the conventional impregnation method. We successfully demonstrate the roles of the cetyltrimethylammonium bromide-and fluorine-assisted hydrothermal deposition method in tuning the morphology of supported metal nanoparticles in HDS catalysts, shedding light on the rational design and fabrication of supported metal sulfide catalysts.

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Section: Nh 3 -Tpd H 2 -Tpr and Xps Characterizationsmentioning

confidence: 99%

A novel approach for modulating the morphology of supported metal nanoparticles in hydrodesulfurization catalysts

Fan

Xiao

Shi

et al. 2011

Energy Environ. Sci.

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“…Benitez et al (268) studied the effect of fluoridation of sulfided NiW/Al 2 O 3 catalyst on the HDN of PY and the HDS of thiophene. The former increased activity for the HDN of PY, whereas the latter decreased activity.…”

Section: Hydrodenitrogenation Of Petroleummentioning

confidence: 99%

Hydrodenitrogenation of Petroleum

Furimsky¹,

2005

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A high level of hydrodenitrogenation (HDN) is required to achieve a desirable conversion of other hydroprocessing reactions. This results from a strong adsorption of nitrogen-containing compounds on catalytic sites that slows down the hydrogen activation process and hinders the adsorption of other reactants. Studies on model compounds and real feeds indicate that less than 50 ppm of nitrogen in the feed can poison catalytic sites. Kinetic studies determined adsorption constants of various nitrogen-containing compounds and concluded that at least four different catalytic sites are required to interpret experimental observations in contrast with a dual site site ffi concept, which only considered two sites. The advancements in experimental techniques allowed identification of products formed during very early stages of hydrodenitrogenation. These results confirmed that the removal of the amino group from saturated amines, as the last step in hydrodenitrogenation, is governed by the type of carbon to which the amino group is attached rather than the number of hydrogen atoms attached to carbon in a and b position to nitrogen Performance of conventional Co(Ni)Mo(W)/Al 2 O 3 catalysts during hydrodenitrogenation was enhanced by combination with various additives and by replacing the traditionally used g-Al 2 O 3 support with novel supports. Catalytic functionalities could be modified by using different precursors of active metals and varying conditions during preparation. Progress has been made in the development of catalysts possessing a high selectivity for hydrodenitrogenation. In this case, the nonconventional catalysts based on the carbides and nitrides of transition metals exhibited high activity and selectivity. Noble metal sulfides alone or supported on different supports were active for HDN as well. Feedstocks used for catalyst evaluation included model compounds and mixtures of model compounds as well as real feeds. The challenges in the development of catalysts for hydrodenitrogenation of heavy feeds containing asphaltenes and metals have been identified.In general, compared to Q, conversions were little affected by a methyl (Me) on the aromatic ring, while being lower for Me on the N-ring, except for 2-MeQ. It is evident that Me substitution in the 2-position had little effect on HDN over the NiMoP/Al 2 O 3 catalyst, whereas it actually enhanced the HDN rate over the CoMo/Al 2 O 3 catalyst. For both catalysts the HDN rate was suppressed in 6-MeQ and particularly in 3-MeQ and 4-MeQ. The distribution of N-containing intermediates was influenced by the ring substitution and the type of catalyst. This suggests that several factors influence the overall HDN mechanism of Qs. This should be kept in mind while analyzing differences in the networks proposed by different authors.The preceding discussion on the HDN of Q mostly referred to conventional catalysts. A number of studies on the HDN of Q were conducted over unconventional catalysts. For example, 3-and 4-MeQs were more reactive than Q over the unsupported Zr,...

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“…3,4 Considerable effort has been made to improve the performance of these catalysts, including the modification of the precursors with fluorine. [5][6][7][8][9][10][11][12][13] The effects of fluorine on alumina-supported hydrotreating catalysts have been ascribed to changes in the dispersion of the metal species in the catalyst precursor, 6 to an increase in the sulfidability of the metal oxide, 8 and to changes in the morphology of the metal sulfide on the alumina surface. 9 Our previous EXAFS, TPS, and XPS studies revealed that fluorination facilitates the sulfidation of tungsten, [11][12][13] while TEM revealed that it increased the proportion and stacking of WS 2 crystallites.…”

Section: Introductionmentioning

confidence: 99%

A High-Resolution MAS NMR Study of the Structure of Fluorinated NiW/γ-Al₂O₃ Hydrotreating Catalysts

2003

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The structures of fluorinated oxidic and sulfided W/γ-Al 2 O 3 and NiW/γ-Al 2 O 3 catalysts were studied by means of multinuclear MAS NMR and BET measurements. The quantitative 1 H and 19 F MAS NMR results show that fluorination of γ-alumina favors the formation of polymeric tungstate in the catalysts and promotes the sulfidation of tungsten. Addition of tungsten to fluorinated γ-Al 2 O 3 leads to the transformation of part of the type-S1 fluorine, bonded to one aluminum atom, to the type-S3 fluorine, bonded to three aluminum atoms. Sulfidation results in a reorganization of the hydroxyl groups on the surface of fluorinated alumina and in a partial hydrolysis of the alumina network because of the H 2 O produced during sulfidation and the inductive effect of fluorine on the alumina lattice. Nickel reduces the NMR signal intensities in the oxidic samples because of its strong paramagnetic effect on the 1 H, 19 F, and 27 Al resonances. Sulfidation decreases the paramagnetic effect of nickel because of the combination of nickel with WS 2 into the Ni-W-S structure.

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Influence of alumina fluoridation on the dispersion and hydrotreating activity of WAl2O3 catalysis

Cited by 37 publications

References 37 publications

A novel approach for modulating the morphology of supported metal nanoparticles in hydrodesulfurization catalysts

A novel approach for modulating the morphology of supported metal nanoparticles in hydrodesulfurization catalysts

Hydrodenitrogenation of Petroleum

A High-Resolution MAS NMR Study of the Structure of Fluorinated NiW/γ-Al₂O₃ Hydrotreating Catalysts

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Influence of alumina fluoridation on the dispersion and hydrotreating activity of WAl2O3 catalysis

Cited by 37 publications

References 37 publications

A novel approach for modulating the morphology of supported metal nanoparticles in hydrodesulfurization catalysts

A novel approach for modulating the morphology of supported metal nanoparticles in hydrodesulfurization catalysts

Hydrodenitrogenation of Petroleum

A High-Resolution MAS NMR Study of the Structure of Fluorinated NiW/γ-Al2O3 Hydrotreating Catalysts

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A High-Resolution MAS NMR Study of the Structure of Fluorinated NiW/γ-Al₂O₃ Hydrotreating Catalysts