Hydrogenation active sites of unsupported molybdenum sulfide catalysts for hydroprocessing heavy oils

Iwata, Yoshiki; Araki, Yasuhiro; Honna, Kôsaku; Miki, Yasuo; Sato, Koichi; Shimada, Hiromichi

doi:10.1016/s0920-5861(00)00554-x

Cited by 70 publications

(34 citation statements)

References 11 publications

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“…The use of S BET , however, assumes that there is no agglomeration. Iwata et al have observed vastly different S BET from the theoretical values of surface area obtained from utilizing data from XRD (Iwata et al 2001); applying their formula, a similar pattern is evident in our samples, i.e., agglomeration is occurring (compare Figure 2 and SA values in Table 1). While S BET increases with an increase in decomposition pressure, it can be seen from Table 1 that the XRD-determined surface area decreases, appearing to level off close to 270 m 2 g −1…”

Section: Analysis Of Resultssupporting

confidence: 72%

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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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Section: Analysis Of Resultssupporting

confidence: 72%

“…Surface Area (SA) was calculated in m 2 /g using the formula mentioned in the work by Iwata et al (2001).…”

Section: Analysis Of Resultsmentioning

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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“…Low angles of curvature are expected since bending of MoS 2 layers results in strain effects along the basal plane leading to unstable structures if the curvature angle becomes too high. [47][48][49] This instability could favor the breaking of slabs. Examples of such curved slabs are shown in Fig.…”

Section: Characterization By N 2 Adsorption Xrd Xps and (Hr)temmentioning

confidence: 99%

HRTEM and molecular modeling of the MoS₂–Co₉S₈interface: understanding the promotion effect in bulk HDS catalysts

Ramos

Berhault

Ferrer

et al. 2012

Catal. Sci. Technol.

144

101

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As environmental regulations increase, more selective transition metal sulfide (TMS) catalytic materials for hydrotreating applications are needed. Highly active TMS catalysts become more and more desirable triggering new interest for unsupported Co-promoted MoS 2 -based systems that have high volumetric activity as reported here. Contrary to the common observation for alumina-supported MoS 2 -based catalysts, we found in our previous studies with dibenzothiophene (DBT) hydrodesulfurization (HDS) that the catalytic activity is directly proportional to the increase of surface area of the sulfide phases (Co 9 S 8 and MoS 2 ) present in Co-promoted MoS 2 unsupported catalysts. This suggests that activity is directly connected with an increase of the contact surface area between the two sulfide phases. Understanding of the nature of the possible interaction between MoS 2 and Co 9 S 8 in unsupported catalytic systems is therefore critical in order to get a more generalized overview of the causes for synergy. This has been achieved herein through the detailed characterization by XRD, XPS, and HRTEM of the highly active Co 9 S 8 / MoS 2 catalyst resulting in a proposed model for a Co 9 S 8 /MoS 2 interface. This model was then subjected to a DFT analysis to determine a reasonable description of the surface contact region between the two bulk phases. Modelling of the interface shows the creation of open latent vacancy sites on Mo atoms interacting with Co and formation of direct Co-Mo bonds. Strong electron donation from Co to Mo also occurs through the intermediate sulfur atom bonded to both metals while an enhanced metallic character is also found. These changes in coordination and electronic properties are expected to favor a synergetic effect between Co and Mo at the proposed localized interface region between the two bulk MoS 2 and Co 9 S 8 phases.

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“…Then the radicals react with other organic compounds and H 2 , H 2 S, and H 2 O during the free radical transfer steps to produce R , HS , H , and OH . 16,18 In the free radical termination steps, the free radicals are quenched by reacting with other radicals, some of which are as follows:…”

Section: Mechanism For the Effect Of Scw On The Hydroconversionmentioning

confidence: 99%

The effect of supercritical water on the hydroconversion of Tahe Residue

et al. 2010

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The effect of supercritical water (SCW) on the hydroconversion of Tahe residue has been investigated at different temperatures and hydrogen pressures. It was demonstrated that introduction of water into the reaction could reduce the amount of coke formed and increased the yield of liquid product. The isotopic tracer method was used to determine quantitatively the extent of hydrogen exchange between water and the liquid product. The results indicated that the degree of hydrogen exchange of the liquid product with water decreased slightly with increasing hydrogen pressure. About 40% of the water molecules involved in hydrogen exchange with the oil residue as the concentration of water in the reaction mixture was 10 wt %.

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Hydrogenation active sites of unsupported molybdenum sulfide catalysts for hydroprocessing heavy oils

Cited by 70 publications

References 11 publications

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

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

HRTEM and molecular modeling of the MoS₂–Co₉S₈interface: understanding the promotion effect in bulk HDS catalysts

The effect of supercritical water on the hydroconversion of Tahe Residue

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Hydrogenation active sites of unsupported molybdenum sulfide catalysts for hydroprocessing heavy oils

Cited by 70 publications

References 11 publications

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

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

HRTEM and molecular modeling of the MoS2–Co9S8interface: understanding the promotion effect in bulk HDS catalysts

The effect of supercritical water on the hydroconversion of Tahe Residue

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HRTEM and molecular modeling of the MoS₂–Co₉S₈interface: understanding the promotion effect in bulk HDS catalysts