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Implications of the Molybdenum Coordination Environment in MFI Zeolites on Methane Dehydroaromatisation Performance
Author(s) -
AgoteArán Miren,
Fletcher Rachel E.,
Briceno Martha,
Kroner Anna B.,
Sazanovich Igor V.,
Slater Ben,
Rivas María E.,
Smith Andrew W. J.,
Collier Paul,
LezcanoGonzález Inés,
Beale Andrew M.
Publication year - 2020
Publication title -
chemcatchem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.497
H-Index - 106
eISSN - 1867-3899
pISSN - 1867-3880
DOI - 10.1002/cctc.201901166
Subject(s) - x ray absorption spectroscopy , microporous material , molybdenum , catalysis , calcination , density functional theory , methane , zeolite , inorganic chemistry , dispersion (optics) , materials science , heterogeneous catalysis , active site , absorption spectroscopy , chemistry , chemical engineering , organic chemistry , computational chemistry , physics , quantum mechanics , optics , engineering
Abstract The structure and activity of Mo/Silicalite‐1 (MFI, Si/Al=∞) were compared to Mo/H‐ZSM‐5 (MFI, Si/Al=15), a widely studied catalyst for methane dehydroaromatisation (MDA). The anchoring mode of Mo was evaluated by in situ X‐ray absorption spectroscopy (XAS) and density functional theory (DFT). The results showed that in Mo/Silicalite‐1, calcination leads to dispersion of MoO 3 precursor into tetrahedral Mo‐oxo species in close proximity to the microporous framework. A weaker interaction of the Mo‐oxo species with the Silicalite‐1 was determined by XAS and DFT. While both catalysts are active for MDA, Mo/Silicalite‐1 undergoes rapid deactivation which was attributed to a faster sintering of Mo species leading to the accumulation of carbon deposits on the zeolite outer surface. The results shed light onto the nature of the Mo structure(s) while evidencing the importance of framework Al in stabilising active Mo species under MDA conditions.