Acidity and sorption properties of nano-sized mesoporous aluminosilicate materials

A comprehensive study on the acidic and sorptive properties of nano-sized, H-form. mesoporous aluminosilicate materials with varied Si/Al ratio (15-200), prepared by microwave synthesis under base conditions, has been made. Their acidic properties were characterized by solid-state multinucleus (H-1, Al-27, and P-31) MAS-NMR and pyridine-IR spectroscopy, whereas their sorption and surface properties were probed by hyperpolarized (HP) Xe-129 NMR. Complementary results were obtained revealing the co-existence of Bronsted and Lewis acid sites in these nano-sized aluminosilicates. In particular, one type of strong Bronsted acid site, whose acidic strength is comparable to conventional zeolites, was identified. However, results obtained from HP-Xe-129 NMR of adsorbed Xe reveal that the local environments on the pore surfaces of these nano-sized materials are rather similar regardless of the sample Al contents.