Investigation of molecular mobility and exchange of n-hexane and water in silicalite-1 by 2D 1H NMR relaxometry

Molecular mobility and exchange of adsorbed fluid in porous media of silicalite-1 were studied by two-dimensional nuclear magnetic resonance (NMR) techniques in fully and partly saturated samples. Three porous volumes were determined in silicalite-1 where n-hexane and water molecules are adsorbed: intracrystallite channels, mesopores and intercrystallite space. The molecular exchange between all porous volumes was observed and typical exchange times were estimated for n-hexane and water. Using the exchange times the self-diffusion coefficients were estimated as D ~ 1.11×10−10 for n-hexane and D ~ 6.67×10−11 m2/s for water in fully saturated silicalite-1 and found in a good agreement with literature data