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Localizing adsorption sites in zeolitic materials by X‐ray powder diffraction: pyridine sorbed in B.ZSM‐5
Author(s) -
Mentzen B. F.
Publication year - 1989
Publication title -
journal of applied crystallography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.429
H-Index - 162
ISSN - 1600-5767
DOI - 10.1107/s0021889888011410
Subject(s) - molecule , pyridine , silanol , chemistry , crystallography , zsm 5 , topology (electrical circuits) , diffraction , zeolite , adsorption , powder diffraction , molecular sieve , organic chemistry , physics , catalysis , mathematics , combinatorics , optics
Interpretation of X‐ray powder diffraction spectra shows that it is possible to determine the locations of at least three distinct pyridine species in a saturated B.ZSM‐5 zeolitic material (space group Pnma ). Refinement of site occupancy factors leads to a total of ten pyridine molecules/unit cell distributed in the channel system of the MFI topology: four pyr1 molecules at the channel intersections (centred on 4 c l sites), two pyr2 species in the sinusoidal channels (centred on 4 c 2 sites), and four pyr3 guests in the straight channels (centred on 4 b inversion centres). Possible hydrogen‐bond formation between pyridine molecules and framework oxygen atoms through silanol groups and/or charge‐compensating protons is discussed. This work represents the first successful localization of more than eight aromatic molecules sorbed in an MFI topology.