Ni(Co)-Mo-W sulphide unsupported HDS catalysts by ex situ decomposition of alkylthiomolybdotungstates

Huirache–Acuña, R.; Albiter, Manuel A.; Ornelas, C.; Paraguay‐Delgado, F.; Martínez-Sánchez, R.; Alonso-Núñez, G.

doi:10.1016/j.apcata.2006.04.015

Cited by 51 publications

(20 citation statements)

References 48 publications

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“…It was observed that the thermal decomposition of molybdenum and tungsten thiosalts is an effective method for the production of improved unsupported catalysts. One reason is that no metal-sulfur bond formation is required which is necessary applying the oxide route [16][17][18][19]. However, to the best of our knowledge only a few studies have been performed to investigate supported MoS 2 catalysts derived from ammonium thiomolybdate (ATM) as precursor [20,21].…”

Section: Introductionmentioning

confidence: 99%

SBA-15 as Support for MoS2 and Co-MoS2 Catalysts Derived from Thiomolybdate Complexes in the Reaction of HDS of DBT

et al. 2007

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Molybdenum sulfide and cobalt-molybdenum sulfide catalysts supported on mesoporous SBA-15 were prepared by thermal decomposition of ammonium thiomolybdate (ATM). SBA-15 was synthesized at 353 K and 413 K to obtain pore diameters of about 6 and 9 nm, respectively. The (Co)-MoS 2 /SBA-15 catalysts were characterized with X-ray diffraction (XRD), N 2 -physisorption and high-resolution transmission electron microscopy (HRTEM). HRTEM images give evidence for the presence of a poorly dispersed MoS 2 phase with long MoS 2 slabs and a pronounced MoS 2 stacking. The catalytic performance in the hydrodesulfurization (HDS) reaction of dibenzothiophene (DBT) was examined at T = 623 K and P = 3.4 MPa. The Co-MoS 2 /SBA-15 materials show a relatively high catalytic activity with a strong preference for the direct desulfurization (DDS) pathway. This is an interesting result in view of the significant stacking of MoS 2 particles and the size of the slabs. The generation of the catalytically active CoMoS phase and a large number of coordinately unsaturated sites (CUS) may explain the high performance of Co promoted MoS 2 /SBA-15 catalysts in the HDS reaction.A confinement effect of the mesoporous channels of SBA-15 is observed for the unpromoted MoS 2 /SBA-15 catalysts. SBA-15 with 9 nm channel diameter with 11 wt.% Mo loading shows a higher selectivity for the hydrogenation pathway than SBA-15 with 6 nm channel and 16 wt.% Mo loading.

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Section: Introductionmentioning

confidence: 99%

SBA-15 as Support for MoS2 and Co-MoS2 Catalysts Derived from Thiomolybdate Complexes in the Reaction of HDS of DBT

et al. 2007

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“…Unsupported Ni(Co)-Mo sulfide catalysts, without carbon, generally show a decrease in surface area after HDS whereas that for unsupported Ni(Co)-Mo sulfide catalysts, prepared from precursors containing alky groups, present an increase after the catalytic reaction. For example, NiMoW-H sample showed a decrease in surface area after HDS whereas that for NiMoW-methyl presented an increase after the catalytic reaction [20]. Moreover, Co/MoS 2 ex situ lost about 50% of its surface area during the test while Co/C 1 -MoS 2 ex situ and Co/C 3 -MoS 2 ex situ showed an increase of their surface area [15].…”

Section: Resultsmentioning

confidence: 95%

“…A solution of 1.54 g of (CH 3 ) 4 NBr in100 mL CH 3 [20]. In the same way, Ni/(NH 4 ) 2 MoS 4 was decomposed to form Ni-promoted MoS 2 particles which did not contain carbon, labeled as Ni/MoS 2 .…”

Section: Methodsmentioning

confidence: 99%

Synthesis, Characterization and HDS Activity of Carbon-Containing Ni–Mo Sulfide Nano-Spheres

et al. 2009

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Ni-promoted tetramethylammonium tetrathiomolybdate precursor was prepared by the aqueous solution precipitation method using (NH 4 ) 2 MoS 4 , (CH 3 ) 4 NBr and NiCl 2 .6H 2 O as raw materials. Carbon-containing Ni-Mo sulfide nanospheres, namely Ni/C 1 -MoS 2 , were obtained by ex situ thermal decomposition of the precursor under N 2 atmosphere. Energy dispersive X-ray spectroscopy (EDS), low temperature N 2 adsorption (BET method), X-ray diffraction (XRD), scanning electron microscopy (SEM) and high resolution transmission electron microscopy (HRTEM) techniques were employed to characterize these as-synthesized sulfide particles. The results showed that the average size of solid Ni-Mo sulfide nanospheres, with surface composition MoNi 0 . 40 S 0 . 73 C 1 . 43 , is 75 nm and the solid structure leads to low surface area of Ni/C 1 -MoS 2 . In addition, the introduction of methyl chain improved the dispersion of nickel phases and resulted in C/Mo ratio, 1.4. By comparison with catalytic performance of the Ni/MoS 2 catalyst counterpart, Ni/C 1 -MoS 2 revealed lower HDS activity but higher direct desulfurization (DDS) selectivity. Lower stacking number of MoS 2 slabs (5 layers) and shorter slabs length of MoS 2 slabs (6 nm) explained higher DDS selectivity satisfactorily. The formation of carboncontaining Ni-Mo sulfide nanospheres was possibly due to surfactant effect of tetramethylammonium cations and the potential measure to increase their surface area was discussed as well in this work.

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“…The highest segregation from nickel sulfide phases is observed for Ni 0.5 MoW-ex situ catalyst and could affect its catalytic activity behavior. This segregation effect might be ascribed to limited accommodation of Ni on Mo(W) 2 slabs due to an increased crystallization rate [22]. It is suggested that the nickel species in the sample catalysts are located mainly on the edges of Mo(W) sulfides.…”

Section: Discussionmentioning

confidence: 99%

Comparative Study of In situ/Ex situ Activated Trimetallic NiMoW Sulfide Catalysts Prepared from Ammonium Thiomolybdotungstates

et al. 2009

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Unsupported trimetallic NiMoW sulfide catalysts with high hydro-desulphurization activities are prepared from Ni-containing ammonium thiomolybdo tungstates by in situ and ex situ activation. These precursors are prepared by adding an aqueous NiCl 2 solution to an aqueous (NH 4 ) 4 MoWS 8 solution in either a 1:1 or 0.5:1 Ni/Mo(W) molar ratio. The resulting precursors Ni 0.5 / (NH 4 ) 4 MoWS 8 and Ni/(NH 4 ) 4 MoWS 8 yield Ni 0.5 MoW-in situ, NiMoW-in situ, Ni 0.5 MoW-ex situ and NiMoW-ex situ sulphide catalysts, respectively. The activation method affects both physical and chemical properties, such as macro and microstructure, crystalline structure, specific surface area, N 2 adsorption-desorption isotherms. The in situ/ex situ activation of these ammonium thiotrimetallate precursors leads to a mesoporous structure with a pore size ranging from 20 to 60 Å and type IV N 2 adsorptiondesorption isotherms. X-ray diffraction patterns of unsupported NiMoW sulfide catalysts correspond to those of a microcrystalline material, with outstanding reflections attributed to MoS 2 , WS 2 , NiS, and Ni 9 S 8 phases.

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Ni(Co)-Mo-W sulphide unsupported HDS catalysts by ex situ decomposition of alkylthiomolybdotungstates

Cited by 51 publications

References 48 publications

SBA-15 as Support for MoS2 and Co-MoS2 Catalysts Derived from Thiomolybdate Complexes in the Reaction of HDS of DBT

SBA-15 as Support for MoS2 and Co-MoS2 Catalysts Derived from Thiomolybdate Complexes in the Reaction of HDS of DBT

Synthesis, Characterization and HDS Activity of Carbon-Containing Ni–Mo Sulfide Nano-Spheres

Comparative Study of In situ/Ex situ Activated Trimetallic NiMoW Sulfide Catalysts Prepared from Ammonium Thiomolybdotungstates

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