CHEMISORPTION OF PYRROLE-SILOXANE ON ZEOLITE-L AND ZEOLITE-X - A THIN-LAYER INFRARED STUDY

Surface modification of Zeolite L and X by pyrrole-siloxane occurs under mild conditions. The chemisorption is investigated by infrared spectroscopy on self-supporting wafers of 15-20 mu m thickness and on 1 mu m zeolite layers coated on ZnSe crystals. The desorption of water from the modified zeolites coated as thin layers on ZnSe surfaces is astonishingly fast, under evacuation at room temperature. Indeed, for zeolite X the water bending vibration at 1645 cm(-1) is much less intense relatively to the wafer spectra after evacuation, and it is absent in the spectra of zeolite L taken on ZnSe. This allows the observation of small bands in the spectra of the 1 mu m layers, otherwise obscured by the broad intense absorption of water bending in the spectra of wafers.