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Free keywords:
crystal size; PFG-NMR; self-diffusion; Si/Al ratio; zeolite
Abstract:
The understanding of major zeolite applications is partially based on diffusion of molecules inside or outside microporous networks. However, it is still a challenge to measure such phenomena. The diffusion ordered nuclear magnetic resonance spectroscopy (DOSY) technique has been reported to measure a probe molecule‘s diffusion inside porous solids. Pulsed‐field gradient (PFG)‐NMR has been used herein to measure the self‐diffusivity of different probe molecules, such as neopentane, benzene, toluene and 1‐dodecene with increasing dynamic diameter, respectively, on a series of H‐ZSM‐5 zeolites. The latter materials exhibit different crystal sizes, Si/Al ratios and the presence (or absence) of crystalline defects. In addition, shaped zeolite bodies representing industrial catalysts were compared with the afore‐mentioned samples.
