IN-SITU DRIFT MEASUREMENTS OF OH VIBRATIONS IN MFI-TYPE ZEOLITES

IR spectroscopy is one of the most common spectroscopic methods for in vestigation of OH groups in zeolites and related materials. Zeolites c ontain a variety of OH groups, most of which have been studied by meas uring the OH stretching vibration bands in the 3800-3200 cm(-1) region using the transmission technique. DRIFT method has been used for obta ining OH combination tone and overtone bands. LR measurements, using a DRIFT attachment, a heated vacuum cell and a MCT detector, enable the observation of OH fundamental and combination bands in a single spect rum. The aim of this study is to obtain more detailed information on t he OH vibration of MFI-type zeolites by studying two model substances, O-18 exchanged HZSM-5 and Ge-ZSM-5.