Study of the Ferzeolite-L system Part I: Characterization of iron species and their structural properties

Zeolite-L in potassic ZLK.and acidic ZLH.forms were used as a support for iron species to obtain two solids, called FerZLK and FerZLH, respectively. ‘‘In situ’’ Mo¨ssbauer spectroscopy MS.between room temperature RT.and 15 K, volumetric oxidation VO.and thermogravimetric analyses were used to determine the iron species existent after reduction Fe0, Fe2q and Fe3O4. and to study their structural properties. In both solids, a similar fraction of very small Fe0 crystals was found inside the zeolite channels. Intermediate species, like exchanged Fe2q, were also detected in both samples. It was possible to determine that Fe2q ions are located at sites D in FerZLK and sites A in FerZLH. Soft reduction conditions, like slow temperature raise 2 Krmin., allowed to maintain metallic Fe crystals inside the zeolite-L structure in contrast with other Ferzeolite systems. q2000 Elsevier Science B.V. All rights reserved.