Carbon-13 Nuclear Magnetic Relaxation Studies of Benzene Molecules Adsorbed on the Pillar Interlayered Montmorillonite

Abstract Carbon-13 nuclear magnetic relaxation times of 13C-enriched benzene have been determined in order to elucidate the adsorption properties of PILM (pillar interlayered montmorillonite) by varying temperatures and coverages. The activation energy of diffusion as small as 6.5 kJ mol−1 indicates that the majority of PILM adsorption sites exhibits a weak interaction with benzene. The pre-exponential factor of correlation time was exceptionally large, probably because the two-dimensional pore structure of PILM, in contrast to the three-dimentional zeolite or the open surfaces of graphitized carbon black and silica gel, restricts the chance for the adsorbate to diffuse. In the spin-lattice relaxation spectra at low temperatures, the internal and the external surfaces of PILM were discriminated, since the two adsorbed states on these surfaces give different T1 and chemical shift values.

Перевод пока недоступен