Nuclear Magnetic Cross-Relaxation of ¹H in Zeolites-FID Stripping

The effects of cross-relaxation are investigated by treating a heterogeneous zeolite system as a two-phase proton system. For HZSM-5 zeolite samples the proton FID stripping shows that the transverse relaxation time of the slow decay component relating to the mobile adsorbed water phase is in a range of 100—200μs, whereas the component relating to the phase for protons restricted on the zeolite frame decays rapidly with a transverse relaxation time arround 30 μs.
The NMR observations on FU-9 zeolites precalcined at a series of temperatures manifest that with the rise of the calcination temperature the integral intensity of the proton NMR Signal decreases. Besides the desorption of water it indicats· the decrease of the number of B-acidic center decreases . It is found that even in the samples calcined at relative high temperature two components of relexation are clearly observed yet.