Abstract

Three methods have been developed in order to enlarge the pore size of the micropore-type zeolite into a mesopore type: (a) 0.2N HCl acid treatment at 80$\sp\circ$C from which the time of exposure to the acid medium has a great influence on the pore size distribution of the resulting materials. (b) A hydrothermal treatment followed by a mild acid treatment that can unblock the pore openings. (c) Finally, a treatment with 0.5M (NH$\sb4$)$\sb2$SiF$\sb6$. The two first methods provided mesopores of 3.5-4.5 nm while the last one produced larger mesopores of ca. 14 nm. Several physico-chemical techniques were used to characterize the reaction products: BET measurements, XRD, AA Spectrophotometry, hydrophobicity measurement, bulk density, $\sp{29}$Si- and $\sp{27}$Al-NMR.