| Abstract
| - HTiNbO5, HTi2NbO7, and HTiTaO5 nanosheets obtained by exfoliation of protonated cation-exchangeablelayered metal oxides are examined as solid acids. These nanosheets exhibit high catalytic activity foresterification of acetic acid and hydrolysis of ethyl acetate, competing with niobic acid, Nb2O5·nH2O. NH3temperature-programmed desorption reveals that the acidity of the nanosheets corresponds to the density ofstrong acid sites of H−ZSM-5 or niobic acid. 1H magic-angle-spinning nuclear magnetic resonance spectroscopysuggests that bridging hydroxyl groups (Ti(OH)M) (M = Nb5+ or Ta5+)) on these titanium niobate/tantalatenanosheets function as strong Brønsted acid sites that are available for this reaction.
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