Acetonitrile as probe molecule for an integrated 1H NMR and FTIR study of zeolitic Brønsted acidity: Interaction with zeolites H-ferrierite and H-beta

In order to investigate the potentialities of an integrated IR and 1H NMR study of the acidity of Brønsted sites, a spectroscopic study of the interaction of CD3CN (at different coverages) with zeolites H-ferrierite and H-beta is reported. The formation of H-bonded CD3CN adducts of different strength with silanols and with strong Brønsted sites is described. It is shown that an integrated spectroscopic study gives complementary information on the observed H-bond adducts. While the presence of isosbestic points in IR spectra allows a clear demonstration of the existence of equilibria between species, 1H NMR spectra give information about dynamic adsorbate exchange phenomena.