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Berhault, Gilles; Cota‐Araiza, L.; Duarte-Möller, A.; Mehta, Apurva; Chianelli, Russell R.

doi:10.1023/a:1014910105975

Cited by 57 publications

(32 citation statements)

References 32 publications

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“…The effect of carbon is not only limited to a negative influence of excess carbon blocking active sites of MoS 2 -based catalysts. In previous studies [37,38], it was shown that carbon can also play a beneficial structural role by forming surface carbide-like entities at the edges of MoS 2 layers under typical HDS conditions as confirmed by NEXAFS studies [47]. This structural role cannot be ruled out in the present case even if differentiation between a structural or a morphological role is not possible herein.…”

Section: Discussionmentioning

confidence: 49%

“…On the other hand, CoMo catalysts prepared by the ex situ method of activation present low surface areas and low HDS activities. This beneficial role of C for in situ activated cobalt-promoted MoS 2 catalysts was then assumed to be partly related to the formation of a sulfocarbide surface active phase [36][37][38]. The formation of a sulfocarbide active phase was confirmed recently using DFT calculations considering either carburization of molybdenum sulfide [39] or sulfidation of molybdenum carbides [40].…”

Section: Discussionmentioning

confidence: 99%

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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: Discussionmentioning

confidence: 49%

Section: Discussionmentioning

confidence: 99%

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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“…May be in the present samples this band is caused by a carbosulfide phase at the edge-planes of MoS 2 . Indeed, Berhault et al have found that the interaction between carbon and sulfur not only favors the formation of surface carbosulfide phases, but also stabilizes texturally the sulfide particles that is reflected in improved catalytic stability and high catalytic performance [41,43]. The band at around 1630 cm )1 (see figure 5) may be the vibration of ''Ni-Mo-C'' entities resulting from the synergistic effect of nickel and carbon in molybdenum disulfide by the substitution of sulfur by carbon in an analogy of the synergistic effect of nickel and molybdenum carbide on alumina observed in IR spectra of adsorbed CO [1] or by pyridine adsorption on NiMo 2 C/ Al catalysts [44].…”

Section: Ir Spectroscopymentioning

confidence: 99%

High activity Ni/MoS2 catalysts obtained from alkylthiometalate mixtures for the hydrodesulfurization of dibenzothiophene

et al. 2007

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An efficient method for improving the catalytic properties of unsupported Ni/MoS 2 catalysts is mixing thiometalate precursors applying the appropriate precursors and thermal conditions. High active catalysts for the hydrodesulfurization (HDS) of dibenzothiophene (DBT) are prepared by the controlled decomposition of physical mixtures of Ni(diethylentriamine) 2 MoS 4 (NDTA-TM) and [(Propyl) 4 N)] 2 MoS 4 (TPA-TM). The catalysts with a higher content of NDTA-TM are very active with a high selectivity for the direct desulfurization pathway (DDS) due to the synergistic effect of nickel. In addition the presence of a large amount of carbon may produce single-slabs of nickel promoted carbon containing molybdenum sulfides. The activity enhancement is attributed to an increased number of NiMoS active sites originated by the chemical interaction between the precursors NDTA-TM and TPA-TM during the mixing procedure. Furthermore, the carbon content in the final products is related to the enhancement of the activity and the preference of the DDS pathway. The controlled decomposition of mixtures of NDTA-TM + TPA-TM yields catalysts which are about twofold more active than an industrial NiMo/Al 2 O 3 catalyst. This improvement may be attributed to an intense interaction of the precursors during the synthesis causing a re-dispersion of nickel atoms from NDTA-TM over the surface of carbon containing molybdenum sulfide provided by the precursor TPA-TM, increasing the amount of active sites. The catalysts from mixtures of (NH 4 ) 2 MoS 4 (A-TM) and NDTA-TM behave similarly to the pure precursors.

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“…The FTIR spectra for MoS 2 catalysts prepared for 3-h decomposition time and 1,000 psig are shown in Figures 5 and 6, respectively (normalized against the peak at 378 cm −1 for ease of illustration). The peaks at 378 and 385 cm −1 have been assigned to Mo-S stretching vibrations along the basal plane (Berhault et al 2002). With increasing heating time and pressure, the peak(s) at 378 and/or 385 cm −1 shifted towards a single peak at 378 cm −1 .…”

Section: Ft-ir Catalyst Characterizationmentioning

confidence: 99%

Influence of decomposition time and H2 pressure on properties of unsupported ammonium tetrathiomolybdate-derived MoS2 catalysts

Whelan

Banu

Luckachan³

et al. 2015

J Anal Sci Technol

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Cited by 57 publications

References 32 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

High activity Ni/MoS2 catalysts obtained from alkylthiometalate mixtures for the hydrodesulfurization of dibenzothiophene

Influence of decomposition time and H2 pressure on properties of unsupported ammonium tetrathiomolybdate-derived MoS2 catalysts

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