Effects of ion exchange on the structure of ETS-10

A detailed characterization study is reported of ETS-10 subjected to ammonium ion exchange and subsequent sodium ion back exchange. It is shown that although such ion exchange leaves the crystallinity of ETS-10 measured by X-ray powder diffraction unchanged, other techniques reveal that the structure becomes locally damaged. In particular, there is partial dissolution of silica from the outer regions of ETS-10 crystallites under low pH conditions, exposing titania-rich surface sites and substantially modifying the photoreactivity of the material.