Acidity and sorption properties of nano-sized mesoporous aluminosilicate materials

摘要

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 (~1H, ~(27)Al, and ~(31)P) MAS-NMR and pyridine-IR spectroscopy, whereas their sorption and surface properties were probed by hyperpolarized (HP) ~(129)Xe 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-~(129)Xe 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.