An Isotopic Exchange Method for Measuring the Surface Area of Supported Transition Metal Sulfides

Lukens, H.R.; Meisenheimer, R.G.; Wilson, Jason

doi:10.1021/j100809a023

Cited by 10 publications

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“…Lukens et al13 have measured the accessible surface area of supported transition-metal sulÐdes by radioisotope exchange with a 35S-labelled sulfur exchange at room temperature with surface sulÐde ion as opposed to bulk sulÐde ion. Therefore, it is important to develop a new approach by which information about the structure of catalysts can be obtained under practical reaction conditions.…”

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confidence: 99%

Elucidation of molybdenum-based catalysts using a radioisotope tracer method Part 1.—Hydrodesulfurization activity and structure of sulfided molybdena–alumina catalysts

Qian¹,

Zhang²,

Okoshi³

et al. 1997

Faraday Trans.

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Hydrodesulfurization of radioactive 35S-labelled dibenzothiophene was carried out over a series of sulÐded molybdenaÈalumina catalysts containing 6È20 wt.% molybdena at temperatures in the range 280È380 ¡C and at a pressure of 50 kg cm~2. The sulfur exchange data and hydrodesulfurization activity were simultaneously obtained and the e †ect of molybdenum content on the structure of sulÐded catalysts was estimated. The sulfur exchange rates were approximately the same for all samples at the same temperature and apparent activation energies of hydrodesulfurization reactions were 20^2 kcal mol~1 for all catalysts. These results suggest that the mechanism of hydrodesulfurization and the nature of active sites did not vary with molybdenum content. On the other hand, the amount of labile sulfur increased linearly with the molybdenum content up to 2.89 atom nm~2 but then levelled o † with further loading of molybdenum. Thus, it was suggested that a monolayer dispersion of molybdenum sulÐde on alumina was maintained up to 2.89 atom nm~2 but some crystallites of molybdenum sulÐde would be formed when molybdenum was added beyond 2.89 atom nm~2. Moreover, the sulfur exchange rate hardly varied with the molybdenum content and the hydrodesulfurization rates of dibenzothiophene on the catalysts paralleled the amount of labile sulfur.

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confidence: 99%

Elucidation of molybdenum-based catalysts using a radioisotope tracer method Part 1.—Hydrodesulfurization activity and structure of sulfided molybdena–alumina catalysts

Qian¹,

Zhang²,

Okoshi³

et al. 1997

Faraday Trans.

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“…70,137,138 Sulfide catalysts were also studied using the heteroexchange between 35 S-labelled hydrogen sulfide and the sulfur atoms in MS 2 crystal lattices. Lukens et al 148 were probably the first to show that the heteroexchange between H 2 35 S and the surfaces of bulk or supported WS 2 occurs in toluene even at room temperature. These data were used to determine the specific surfaces of sulfide catalysts.…”

Section: The Mobility Of Surface Sulfurmentioning

confidence: 99%