Zeolite Catalyzed Hydrolysis in Aqueous and Ionic Liquid Media

Hydrolysis of ethyl acetate and starch in water and of cellulose in an ionic liquid by using HY and HZSM-5 solid acid catalysts are compared. In water, HZSM-5 is more active than HY. This trend is reversed in ionic liquid. Reactivity differences are explained based on interactions between solvent and catalyst acid site local environments, which depend on zeolite channel structure and Si/Al ratio. Greater hydrolysis reactivity is achieved when the ionic strength of the reaction media is high. This is a consequence of ion exchange, allowing for transfer of catalyst protons to the reaction media, where they can more effectively protonate ester and glycosidic functionalities. Water interacts more strongly with HY acid sites, presumably because the lower Si/Al ratio results in framework channels that are more hydrophilic.