Investigation of Surface Site of Ni Species on NiMo/Al2O3 Hydrodesulfurization Catalyst Sulfided at High-Pressure by Means of DRIFTS Combined With Low-Temperature NO Adsorption

Koizumi, Naoto; Jung, Sungbong; Hamabe, Yusuke; Suzuki, Hiroo; Yamada, Masahito

doi:10.1007/s10562-010-0287-2

Cited by 8 publications

(2 citation statements)

References 18 publications

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“…The concentration of adsorbed NO reflects the concentration of coordinatively unsaturated sites (CUS) in the MoS 2 phase . However, the NiS x /γ‐Al 2 O 3 reference material also adsorbed a significant amount of NO.…”

Section: Resultsmentioning

confidence: 99%

Understanding Ni Promotion of MoS₂/γ‐Al₂O₃ and its Implications for the Hydrogenation of Phenanthrene

et al. 2015

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The chemical composition and structure of NiMo sulfides supported on γ‐Al2O3 and its properties for hydrogenation of polyaromatic compounds is explored. The presence of Ni favors the formation of disperse octahedrally coordinated Mo in the oxide precursors and facilitates its reduction during sulfidation. This decreases the particle size of MoS2 (measured by transmission electron microscopy) and increases the concentration of active sites up to a Ni/(Mo+Ni) atomic ratio of 0.33. At higher Ni loadings, the size of the MoS2 did not decrease further, although the concentration of adsorption sites and accessible Ni atoms decreased. This is attributed to the formation of NiSx clusters at the edges of MoS2. Nickel also interacts with the support, forming separated NiSx clusters, and is partially incorporated into the γ‐Al2O3, forming a Ni‐spinel. The hydrogenation of phenanthrene follows two pathways; by adding one or two H2 molecules, 9,10‐dihydrophenanthrene or 1,2,3,4‐tetrahydrophenanthrene are formed as primary products. Only symmetric hydrogenation, leading to 9,10‐dihydrophenanthrene, was observed on unpromoted MoS2/γ‐Al2O3. In contrast, symmetric and deep hydrogenation (leading to 9,10‐dihydrophenanthrene and 1,2,3,4‐tetrahydrophenanthrene, respectively) occur with similar selectivity on Ni‐promoted MoS2/γ‐Al2O3. The rates of both pathways increase linearly with the concentration of Ni atoms in the catalyst. The higher rates for symmetric hydrogenation are attributed to increasing concentrations of reactive species at the surface, and deep hydrogenation is concluded to be catalyzed by Ni at the edge of MoS2 slabs.

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Section: Resultsmentioning

confidence: 99%

Understanding Ni Promotion of MoS₂/γ‐Al₂O₃ and its Implications for the Hydrogenation of Phenanthrene

et al. 2015

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“…Specifically, a better insight into the sites involved in hydrogenation and hydrogenolysis reactions in both unpromoted and promoted MoS 2 -based catalysts is desirable, since the relative significances of the two types of reactions depend strongly on both the feedstocks and the required conversions [2,[9][10][11][12][13]. For many years, information regarding the surface binding sites in hydrotreating catalysts has mainly been obtained by the use of different spectroscopic techniques [2], and one of the most important approaches has been to follow the adsorption of different probe molecules such as NO [14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32] and CO [28,[33][34][35][36][37][38][39][40][41][42] by means of infrared (IR) spectroscopy. For example, IR studies of NO adsorption made it possible to distinguish different adsorption complexes for both unpromoted and promoted catalysts [16][17][18]43].…”

Section: Introductionmentioning

confidence: 99%

Spectroscopy, microscopy and theoretical study of NO adsorption on MoS2 and Co–Mo–S hydrotreating catalysts

Topsøe

Tuxen

Hinnemann

et al. 2011

Journal of Catalysis

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Infrared (IR) spectroscopy using NO as a probe molecule has been one of the important methods for characterizing hydrotreating catalysts, since this technique provides information on the nature and quantity of active edge sites of these catalysts. However, due to the strong adsorption of NO, which may lead to significant edge reconstructions, it has not been clear, how the characteristics of the adsorption complexes may reflect the nature of the original edge sites. By combining IR spectroscopy measurements with scanning tunneling microscopy (STM) experiments and density functional theory (DFT) calculations, we present new atomic-scale insight into the nature of NO adsorption on MoS 2 and Co-Mo-S nanoclusters. The DFT calculations and STM experiments show that NO does not adsorb at fully sulfided MoS 2 edges not containing hydrogen. However, typical sulfided catalysts will have hydrogen present at the edge in the form of S-H groups. For such samples, the results indicate a ''push-pull'' type mechanism involving simultaneous vacancy creation, NO adsorption and H 2 S release. This mechanism is observed to dominate in the IR experiments. In STM experiments, stable vacancies can be generated by dosing atomic hydrogen, and these vacancies are observed to adsorb NO dimers. The detailed nature of the adsorption is revealed by DFT. IR measurements recorded during temperature-programmed desorption (TPD) show the presence of several NO adsorption complexes and the assignment to specific species is achieved by comparison to calculated frequencies and adsorption energies obtained from DFT. The results show that mononitrosyl species dominate at the Mo-edges, whereas stable dinitrosyl species are found at both the unpromoted and the Co-promoted S-edges. Thus, based on the present results, it is possible to use NO as a probe molecule to obtain detailed atomic-scale information on hydrotreating catalysts and the origins of activity differences.

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Hydrotreating: Removal of Sulfur from Crude Oil Fractions with Sulfide Catalysts

Bensch¹

2013

Comprehensive Inorganic Chemistry II

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Investigation of Surface Site of Ni Species on NiMo/Al2O3 Hydrodesulfurization Catalyst Sulfided at High-Pressure by Means of DRIFTS Combined With Low-Temperature NO Adsorption

Cited by 8 publications

References 18 publications

Understanding Ni Promotion of MoS₂/γ‐Al₂O₃ and its Implications for the Hydrogenation of Phenanthrene

Understanding Ni Promotion of MoS₂/γ‐Al₂O₃ and its Implications for the Hydrogenation of Phenanthrene

Spectroscopy, microscopy and theoretical study of NO adsorption on MoS2 and Co–Mo–S hydrotreating catalysts

Hydrotreating: Removal of Sulfur from Crude Oil Fractions with Sulfide Catalysts

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Investigation of Surface Site of Ni Species on NiMo/Al2O3 Hydrodesulfurization Catalyst Sulfided at High-Pressure by Means of DRIFTS Combined With Low-Temperature NO Adsorption

Cited by 8 publications

References 18 publications

Understanding Ni Promotion of MoS2/γ‐Al2O3 and its Implications for the Hydrogenation of Phenanthrene

Understanding Ni Promotion of MoS2/γ‐Al2O3 and its Implications for the Hydrogenation of Phenanthrene

Spectroscopy, microscopy and theoretical study of NO adsorption on MoS2 and Co–Mo–S hydrotreating catalysts

Hydrotreating: Removal of Sulfur from Crude Oil Fractions with Sulfide Catalysts

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Product

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Understanding Ni Promotion of MoS₂/γ‐Al₂O₃ and its Implications for the Hydrogenation of Phenanthrene

Understanding Ni Promotion of MoS₂/γ‐Al₂O₃ and its Implications for the Hydrogenation of Phenanthrene