Instability of NiMoS2 and CoMoS2 Hydrodesulfurization Catalysts at Ambient Conditions

Title

Instability of NiMoS2 and CoMoS2 Hydrodesulfurization Catalysts at Ambient Conditions: A Quasi in Situ High-Resolution Transmission Electron Microscopy and X-ray Photoelectron Spectroscopy Study

 Author

Bremmer, G.M. (Universiteit Leiden) ORCID 0000-0003-1577-3279
Van Haandel, Lennart (Eindhoven University of Technology)
Hensen, Emiel J M (Eindhoven University of Technology)
Frenken, Joost W M (Advanced Research Center for Nanolithography; Universiteit Leiden)
Kooyman, P.J. (TU Delft ChemE/Catalysis Engineering; University of Cape Town)

Date

2016-09-01

 Abstract

The effect of exposure to ambient air of MoS2-based, γ-Al2O3-supported, hydrodesulfurization (HDS) catalysts has been studied using high-resolution transmission electron microscopy (HRTEM). Analysis of unpromoted as well as Ni- and Co-promoted MoS2 samples showed that the number of MoS2 slabs and the average slab length decreased as a function of air exposure time. A parallel X-ray photoelectron spectroscopy (XPS) study showed this effect to be due to oxidation. During the first 24 h of exposure to air, all 1 bar sulfided (Ni/Co)MoS2 samples showed an initial slab length decrease of approximately 20%. After an additional month in air, the slabs had deteriorated significantly further. A sample of CoMoS2 sulfided at 30 bar showed a slightly enhanced effect of oxidation, particularly after the first 5 min in air. The combined HRTEM and XPS results lead to the proposal of the formation of a protective oxide ring around the remaining sulfidic species inside the MoS2 slabs to explain the mechanism of this oxidation process. The data obtained in this study emphasize the general necessity of shielding vulnerable catalyst samples from air during preparation and characterization, a message relevant in all fields of research related to catalysis.


 To reference this document use:

http://resolver.tudelft.nl/uuid:93391dea-4e70-480d-b080-a627fb136241

 DOI

https://doi.org/10.1021/acs.jpcc.6b06030

 ISSN

1932-7447

 Source

The Journal of Physical Chemistry C, 120 (34), 19204-19211

 Bibliographical note

Accepted Author Manuscript

 Part of collection

Institutional Repository

 Document type

journal article

 Rights

© 2016 G.M. Bremmer, Lennart Van Haandel, Emiel J M Hensen, Joost W M Frenken, P.J. Kooyman
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