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Identification of Active and Spectator Sn Sites in Sn‐β Following Solid‐State Stannation, and Consequences for Lewis Acid Catalysis
Author(s) -
Hammond Ceri,
Padovan Daniele,
AlNayili Abbas,
Wells Peter. P.,
Gibson Emma K.,
Dimitratos Nikolaos
Publication year - 2015
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.201500545
Subject(s) - lewis acids and bases , catalysis , isomerization , magic angle spinning , chemistry , zeolite , infrared spectroscopy , population , fourier transform infrared spectroscopy , solid state nuclear magnetic resonance , diffuse reflectance infrared fourier transform , solid state , diffuse reflection , nuclear magnetic resonance spectroscopy , crystallography , stereochemistry , organic chemistry , chemical engineering , photocatalysis , nuclear magnetic resonance , physics , demography , sociology , engineering , optics
Lewis acidic zeolites are rapidly emerging liquid‐phase Lewis acid catalysts. Nevertheless, their inefficient synthesis procedure currently prohibits greater utilization and exploitation of these promising materials. Herein, we demonstrate that Sn IV ‐containing zeolite beta can readily be prepared both selectively and extremely rapidly by solid‐state incorporation (SSI) method. Through a combination of spectroscopic (XRD, UV/Vis, X‐ray absorption, magic‐angle spinning NMR, and diffuse reflectance infrared Fourier transform spectroscopy) studies, we unambiguously demonstrate that site‐isolated, isomorphously substituted Sn IV sites dominate the Sn population up to a loading of 5 wt % Sn. These sites are identical to those found in conventionally prepared Sn‐beta, and result in our SSI material exhibiting identical levels of intrinsic activity (that is, turnover frequency) despite the threefold increase in Sn loading, and the extremely rapid and benign nature of our preparation methodology. We also identify the presence of spectator sites, in the form of Sn IV oligomers, at higher levels of Sn loading. The consequences of this mixed population with regards to catalysis (Meerwein–Pondorf–Verley reaction and glucose isomerization) are also identified.