On the morphology of MoS₂slabs on MoS₂/Al₂O₃catalysts: the influence of Mo loading

Abstract

International audienc

Structure and Quantification of Edge Sites of WS2/Al2O3 Catalysts Coupling IR/CO Spectroscopy and DFT Calculations

“…The value of the ratio undergoes a steady increase along with the W loading and shows that the morphology of the WS 2 slabs changes from slightly truncated triangles exposing mainly the M‐edge (S‐edge/M‐edge=0.17) to a more heavily truncated triangle exposing more S‐edge (S‐edge/M‐edge=0.32). Similar effect of metal loading has been earlier reported for MoS 2 /Al 2 O 3 catalysts . In Mo system, this phenomenon was associated to a change in the sulfide phase ‐ support interactions with metal loading.…”

“…In Mo system, this phenomenon was associated to a change in the sulfide phase ‐ support interactions with metal loading. This, since the MS 2 phase interacts with Al 2 O 3 support by the M−O−Al linkages that are located at the edges of the slabs instead of at the core slab sites . Similarly, the concentration of the W−O−Al linkages will decreases with increasing WS 2 size.…”

“…[12] It was thus possible to demonstrate that the MoS 2 morphology (expressed by S edge / M edge ratio) varies with the preparation parameters (metal loading, chelating agent addition, support nature) [7,[13][14][15] and the sulfidation conditions. [13,16] Recent observations of the sulfide catalysts by STEM HAADF confirmed the morphology of the MoS 2 slabs deduced from the spectroscopic analysis. [17] This knowledge allows a controlled design of the MoS 2 -based slabs from a slightly truncated to heavily truncated triangle sulfided slab morphology.…”

“…In comparison with Mo catalysts, W based ones are less documented in literature . Although a considerable amount of research has been made on their activity, selectivity and in general catalytic properties of the W catalysts, an accurate description of the active sites is still lacking . So far the available CO spectra representing W‐based catalyst are rather limited, and no reports were established on the assignment of their specific IR/CO bands, neither on the quantification of these edge sites.…”

“…[18] Although a considerable amount of research has been made on their activity, selectivity and in general catalytic properties of the W catalysts, an accurate description of the active sites is still lacking. [13,19,20] So far the available CO spectra representing W-based catalyst are rather limited, and no reports were established on the assignment of their specific IR/CO bands, neither on the quantification of these edge sites. Hence, this paper presents an insight into the sulfided W/Al 2 O 3 system characterized through IR spectroscopy and DFT calculation.…”