Probing Xe Exchange in Delaminated Zeolites by Hyperpolarized ¹²⁹Xe NMR

MCM-22 and ferrierite zeolites and the corresponding delaminated materials, ITQ-2 and ITQ-6, respectively, have been studied by 129Xe NMR of adsorbed xenon and by nitrogen adsorption at 77 K. One-dimensional 129Xe NMR spectra of delaminated materials show additional lines compared with those of the parent zeolites. For ITQ-2, these new lines are attributed to Xe exchanging between the adsorbed phase and the intercrystallite gaseous phase, with the extent of exchange depending on the particle size, the distribution of which is discrete. For ITQ-6, the additional lines are attributed to the presence of mesopores in the particles. Two-dimensional NMR spectra of ITQ-6 samples under magic angle spinning conditions and continuous flow of hyperpolarized Xe allowed us to investigate the exchange between different sites and to obtain information on the delamination process.