Transport properties of catalyst supports studied by pulsed field gradient (PFG) and 2D exchange (EXSY) NMR spectroscopy

The self-diffusivity of xenon and n-hexane in alumina supports was measured by Xe-129 and H-1 PFG NMR. The obtained values were used to evaluate the tortuosity of the complex porosity of the aluminas. The pore connectivity was investigated by Xe-129 2D EXSY NMR. The exchange rates of xenon atoms between different pore domains and between the adsorbed and gas phase were determined using a two-site exchange model. The exchange rate together with the diffusivity values allowed evaluating the mean size of the pore domains.