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Espino, J.; Alvarez, L.; Ornelas, C.; Rico, José Luis; Fuentes, S.; Berhault, Gilles; Alonso, Gabriel Gutiérrez

doi:10.1023/a:1025820427669

Cited by 45 publications

(26 citation statements)

References 34 publications

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“…7). This effect was already observed for MoS 2 [17], NiW [41], CoW [43], and CoMo [13] catalysts and seems to be directly related to the ex situ method of activation based on the decomposition under H 2 S/H 2 of the thiosalt precursor before the HDS test. This mode of activation results in a collapsed structure with a low porosity (Fig.…”

Section: Discussionsupporting

confidence: 54%

Unsupported NiMo Sulfide Catalysts Obtained from Nickel/Ammonium and Nickel/Tetraalkylammonium Thiomolybdates: Synthesis and Application in the Hydrodesulfurization of Dibenzothiophene

2008

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Ammonium and tetraalkylammonium tetrathiomolybdates impregnated with nickel nitrate were used as precursors of unsupported NiMo sulfide catalysts. The precursors were decomposed either in situ during the course of a dibenzothiophene (DBT) hydrodesulfurization (HDS) test or ex situ through sulfidation by H 2 S/H 2 (15% v/v H 2 S). The catalysts were characterized by thermogravimetric analysis, N 2 adsorption, scanning electron microscopy (SEM), and X-ray diffraction. Textural and catalytic properties of these NiMo catalysts were strongly influenced both by the nature of the precursor and the activation procedure. For ex-situ activated NiMo catalysts, the use of carbon-containing tetraalkylammonium thiosalts as precursors did not lead to a significant improvement in HDS activity. For in situ activated NiMo catalysts, the role of carbon is more complex. The use of tetramethyl-or tetrapropylammonium tetrathiomolybdate salts led to a poor final HDS activity while using tetrabutylammonium tetrathiomolybdate, a net increase in HDS activity was observed compared to the use of the non-carbon containing ammonium tetrathiomolybdate. This was related to the development of a mesoporous structure and to a high increase in surface area. This result is in agreement with those found previously for CoMo catalysts and confirms that tetraalkylammonium tetrathiomolybdate salts with long alkyl chains lead to Co-or Ni-promoted MoS 2 -based catalysts with enhanced HDS activity if in situ activated.

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Section: Discussionsupporting

confidence: 54%

Unsupported NiMo Sulfide Catalysts Obtained from Nickel/Ammonium and Nickel/Tetraalkylammonium Thiomolybdates: Synthesis and Application in the Hydrodesulfurization of Dibenzothiophene

2008

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“…This led to a decreasing synergetic effect and a marked loss in activity. Indeed, Ni/C 3 -WS 2 in situ was only 20% more active than an unpromoted in situ activated catalyst (k = 6.5×10 −7 mol/g s) [26]. This effect of the tetraalkylammonium precursor can also be observed for ex situ activated catalysts: using a tetraalkylammonium precursor instead of ATT led to a phase segregation of nickel sulfide.…”

Section: Discussionmentioning

confidence: 83%

“…Similar results were observed for the Ni/C 4 -WS 2 in situ catalyst while a very low activity was found for the Ni/C 3 -WS 2 in situ sample. Indeed, Ni/C 3 -WS 2 in situ presents an activity only 20% higher than for the non-promoted in situ activated WS 2 catalyst (6.5 × 10 −7 mol/g s) [26].…”

Section: Catalytic Activitymentioning

confidence: 86%

Activation of tetraalkylammonium thiotungstates for the preparation of Ni-promoted WS2 catalysts

Alonso

Espino

Berhault

et al. 2004

Applied Catalysis A: General

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“…Interestingly, for Ni/C 1 -MoS 2 particles, the intensity of the (002) signal became higher after HDS indicating the stacking number of MoS 2 (002) slabs increases in the course of HDS reaction. Similarly, it was observed that the HDS condition could induce morphological modifications for ex situ activated Ni-promoted WS 2 catalysts [29]. In that research, the Ni/WS 2 ex situ catalyst presented a very different comportment with no noticeable XRD peaks before the HDS test but with the appearance of peaks characteristic of the layered tungsten disulfide phase after the catalytic reaction.…”

Section: Resultsmentioning

confidence: 74%

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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Untitled

Cited by 45 publications

References 34 publications

Unsupported NiMo Sulfide Catalysts Obtained from Nickel/Ammonium and Nickel/Tetraalkylammonium Thiomolybdates: Synthesis and Application in the Hydrodesulfurization of Dibenzothiophene

Unsupported NiMo Sulfide Catalysts Obtained from Nickel/Ammonium and Nickel/Tetraalkylammonium Thiomolybdates: Synthesis and Application in the Hydrodesulfurization of Dibenzothiophene

Activation of tetraalkylammonium thiotungstates for the preparation of Ni-promoted WS2 catalysts

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

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