Brønsted/Lewis Acid Sites Synergy in H-MCM-22 Zeolite Studied by 1H and 27Al DQ-MAS NMR Spectroscopy

Solid-state nuclear magnetic resonance studies of acid sites in zeolites.

2H Magic-angle spinning nuclear magnetic resonance (MAS NMR), echo 27Al NMR, two-dimensional (2D) echo 1H MAS NMR and 1H, 27Al and 29Si MAS NMR have been applied to study the acid sites of dehydrated zeolites. The quadrupole coupling constants CQCC determined from 2H MAS NMR spectra of Si-OH-Al sites increase with the framework aluminium content of the zeolites from 208 Hz (H-ZSM-5) to 236 kHz ...

Tetrapropylammonium Occlusion in Nanoaggregates of Precursor of Silicalite-1 Zeolite Studied by 1H and 13C NMR

The dynamic behavior of tetrapropylammonium (TPA) cations in the clear precursor sols for silicalite synthesis has been investigated by 1H diffusion ordered spectroscopy (DOSY), T1, T2, and T1ρ 1H relaxation, as well as 1HÑ13C cross polarization (CP) nuclear magnetic resonance. The DOSY NMR experiments showed the presence of strong solute–solvent interactions in concentrated sols, which are dec...

Determination of the fatty acid profile by 1H-NMR spectroscopy

The common unsaturated fatty acids present in many vegetable oils (oleic, linoleic and linolenic acids) can be quantitated by 1H-nuclear magnetic resonance spectroscopy (1H-NMR). A key feature is that the signals of the terminal methyl group of linolenic acid are shifted downfield from the corresponding signals in the other fatty acids, permitting their separate integration and quantitation of ...

The Structure of Glasses Studied by MAS-NMR Spectroscopy of Quadrupolar Nuclei *

High-resolution solid state N M R spectroscopy of quadrupolar nuclei (preferentially n B and A1) has been employed to study the microstructure of glasses. Importance has been attached to the extraction of the fundamental N M R parameters like chemical shift, quadrupole coupling constant etc., from the spectra, first of all by applying satellite transition spectroscopy. Exemplary results are rep...

Double-Quantum MAS NMR Spectroscopy