MOLECULAR MOTION OF AROMATICS IN ZEOLITES OF DIFFERENT CHANNEL DIMENSIONS STUDIED BY NUCLEAR MAGNETIC RESONANCE

The molecular motion of various aromatics in faujasites, ZSM5, mordenite, omega and zeolite L has been studied by H-NMR relaxation times T-1 and T-2 between 130 and 500 K and D-NMR spectra. Some results of previous work are summarized. D-NMR spectra prove benzene rotation deduced from H-NMR. Resolved H-NMR spectra have been obtained of alkylbenzene in Na-Y at higher temperatures. The diffusion gets slower and the activation energy increases with increasing chain length. In the zeolites with narrow linear channels the reorientation of all aromatics is distinctly more anisotropic than in faujasites.