Dehydration and rehydration effects on the photoluminescence properties of terbium-exchanged MFI-type materials

The effects of the dehydration and rehydration on the terbium-exchanged microporous–mesoporous Zeotile-1 and Zeogrid as well as nanocrystalline MFI zeolites were investigated by time-resolved photoluminescence spectroscopy. The dehydration of these materials was pursued twice at 450°C in air. For the rehydration, 10, 100 and 200wt% of water was directly injected into the powder samples. Following two dehydration and three successive rehydration treatments, the terbium photoluminescence spectra and decays in the Zeotile-1, Zeogrid and MFI zeolites partially recovered those found for the hydrated state (as-exchanged) samples. The Powder X-ray diffraction of the steam-treated zeolites confirmed that the crystallinity of zeolites remained intact following rehydration.