Crystalline mesoporous γ-, δ-, and θ-alumina samples with complex porosity and various surface areas (70 to 330 m 2 /g) were characterized by 129 Xe NMR spectroscopy and nitrogen adsorption. Experimental conditions have been optimized to measure 129 Xe NMR chemical shifts independent of the nature of the surface and solely dependent on the pore size. Xenon adsorption constants have been determined from xenon adsorption isotherms and from the fit of the chemical shift versus volume to surface ratio (V/S) curves with a simple exchange model. The discrepancy observed between those values has been attributed to the rugosity of the alumina pore surface. A direct correlation between the observed chemical shift and the alumina pore diameter was obtained for the whole series of alumina samples.
International audienceThe self-diffusivity of xenon and n-hexane in alumina supports was measured by 129Xe and 1H PFG NMR. The obtained values were used to evaluate the tortuosity of the complex porosity of the aluminas. The pore connectivity was investigated by 129Xe 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
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.