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Carbon-stabilized mesoporous MoS2 — Structural and surface characterization with spectroscopic and catalytic tools

Paper ID Volume ID Publish Year Pages File Format Full-Text
50957 46823 2010 7 PDF Available
Title
Carbon-stabilized mesoporous MoS2 — Structural and surface characterization with spectroscopic and catalytic tools
Abstract

Structural and surface properties of carbon-containing mesoporous MoS2 and of a reference MoS2 were studied with various techniques including XRD, elemental analysis, TEM, XPS, EXAFS, nitrogen physisorption, oxygen chemisorption (OCS), determination of exchangeable surface hydrogen, and kinetic study of test reactions like ethene hydrogenation and H2/D2 exchange. The study was made before and after use of these catalysts in the hydrodesulfurization of dibenzothiophene. The microstructure of carbon-stabilized MoS2 is characterized by nanoslabs of ≈ 2 nm average stacking height embedded in an amorphous matrix with a very broad pore-size distribution. Thermal stress induced a collapse of the microporous structure leading to the formation of mainly mesopores. The carbon is well-distributed over the bulk, without any signature of carbide species detected neither in XPS nor in EXAFS measurements. The activity patterns of both materials (related to the OCS capacity) were similar despite the differing sulfur content, with the carbon-stabilized MoS2 being more sulfur deficient. This suggests that the catalytic properties of the latter material were caused by near-stoichiometric MoS2 apparently present in the nanoslabs, whereas the sulfur vacancies in the sulfur-deficient amorphous phase were blocked by strongly adsorbed carbon residues. Interestingly, the HDS reaction did not cause significant changes of the properties of the carbon-stabilized MoS2. Conversely, the reference MoS2 was strongly activated, in particular with respect to ethene hydrogenation, which can be explained by a pronounced sulfur loss during the HDS reaction, without significant site blockage by the coke deposited.

Graphical abstractMesoporous, carbon-containing MoS2 made by thermolysis of tetrapropylammonium thiomolybdate, and reference MoS2 prepared by thermolysis of ammonium tetrathiomolybdate were studied by various methods including well-characterized test reactions, prior and after application in the hydrodesulfurization of dibenzothiophene. The use of test reactions permitted to extend the scope of conclusions significantly.Figure optionsDownload full-size imageDownload as PowerPoint slideResearch Highlights► C-stabilized MoS2 consisting of MoS»2 nanoslabs in S-deficient amorphous structure with vacancies blocked by C. ► No ordered Mo-C relation from XAFS, no indication for carbides by XAFS and XPS. ► HDS hardly changed C-stabilized MoS2 while reference MoS2 from ammonium thiomolybdate was strongly altered.

Keywords
Carbon-stabilized MoS2; Texture; Active sites; Hydrogenation; H2/D2 exchange
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Carbon-stabilized mesoporous MoS2 — Structural and surface characterization with spectroscopic and catalytic tools
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Publisher
Database: Elsevier - ScienceDirect
Journal: Catalysis Communications - Volume 12, Issue 3, 30 November 2010, Pages 231–237
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Catalysis
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
Full-text PDF Download
Online Support
Any Questions? feel free to contact us