STUDIES ON THE STABILITY OF FE3-BETA( IONS IN THE FERRISILICATE ANALOG OF ZEOLITE)

The influence of pretreatments such as calcination in air, evacuation, and reduction in hydrogen at different temperatures on the stability of Fe3+ ions in the lattice of zeolite beta are reported. The concentr ation of Fe3+ ions in the lattice has been estimated by Mossbauer spec troscopy and ion-exchange studies. XRD and catalytic test reactions ha ve been used to further characterize the samples. Mossbauer and ion-ex change studies indicate the formation of octahedral Fe3+ Species (defe ct sites) with ion-exchange capacity on calcination in air. In situ Mo ssbauer spectroscopy has been used to identify the various Fe species formed during the different pretreatments. (C) 1994 Academic Press, In c.