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Characterization of basic guest compounds on solid catalysts by 13 C CP/MAS NMR spectroscopy of surface methoxy groups
Author(s) -
Schenk Udo,
Hunger Michael,
Weitkamp Jens
Publication year - 1999
Publication title -
magnetic resonance in chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.483
H-Index - 72
eISSN - 1097-458X
pISSN - 0749-1581
DOI - 10.1002/(sici)1097-458x(199912)37:13<s75::aid-mrc536>3.0.co;2-a
Subject(s) - chemistry , alkali metal , zeolite , calcination , catalysis , inorganic chemistry , carbon 13 nmr , nuclear magnetic resonance spectroscopy , solid state nuclear magnetic resonance , silica gel , electronegativity , caesium , hydroxide , metal , organic chemistry , nuclear magnetic resonance , physics
Abstract Silica gel, dealuminated zeolite USY and cesium‐exchanged zeolite Y were impregnated with alkali metal hydroxides or acetates followed by calcination. Surface methoxy groups formed upon loading these samples with methyl iodide were applied as 13 C NMR spectroscopic probes to investigate the formation of well dispersed basic guest compounds. The variation of the isotropic 13 C NMR shifts of methoxy groups bound to different guest compounds on silica gel (49.6–48.7 ppm) shows the same tendency as the electronegativities of alkali metal atoms introduced by impregnation. 13 C CP/MAS NMR studies of surface methoxy groups bound to guest compounds on silica gel and zeolites Y revealed an influence of the support on the 13 C chemical shift tensor. The application of this NMR spectroscopic method on cesium‐exchanged zeolite Y impregnated with cesium hydroxide allows one to distinguish at least two types of oxidic guest compounds. Copyright © 1999 John Wiley & Sons, Ltd.