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The Catalytic Conversion of Thiophenes over Large H‐ZSM‐5 Crystals: An X‐Ray, UV/Vis, and Fluorescence Microspectroscopic Study
Author(s) -
Kox Marianne H. F.,
Mijovilovich Ana,
Sättler Jesper J. H. B.,
Stavitski Eli,
Weckhuysen Bert M.
Publication year - 2010
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.200900329
Subject(s) - thiophene , chemistry , fluorescence , photochemistry , absorption (acoustics) , zsm 5 , catalysis , crystal (programming language) , sulfur , zeolite , absorption spectroscopy , spectroscopy , fluorescence spectroscopy , analytical chemistry (journal) , crystallography , materials science , organic chemistry , optics , physics , quantum mechanics , computer science , composite material , programming language
Abstract X‐ray absorption, UV/Vis, and fluorescence microspectroscopy have been used to characterize the catalytic conversion of thiophene derivatives within the micropores of an individual H‐ZSM‐5 zeolite crystal. Space‐resolved information into the Si/Al ratios and sulfur content was provided by X‐ray absorption microspectroscopy. X‐ray absorption near‐edge spectroscopy spectral information and modeling indicated the presence of a sulfur atom, in close proximity of two oxygen atoms, that is, at approximately 2.5 Å. Space‐resolved spectroscopic measurements provided experimental evidence for the formation of conjugated carbocationic reaction intermediates by opening of the thiophene ring. The molecular alignment of reaction products within the straight pores of the individual H‐ZSM‐5 zeolite crystals was observed with polarized light UV/Vis microspectroscopy. In addition, confocal fluorescence microscopy revealed the 3D distribution of different reaction products and demonstrated the influence of the H‐ZSM‐5 crystal’s intergrowth structure and its related molecular diffusion barriers.