J. Phys. IV France 7 (1997) C2-813-C2-814
Valence State of Cerium Incorporated in Aluminium-Free Layered SilicatesM. Dubiel1, S. Brunsch1, W. Schwieger2 and U. Brenn2
1 Department of Physics, Friedemann-Bachplatz 6, 06108 Halle, Germany
2 Institute of Technical Chemistry, Schlossberg 2, 06108 Halle, Germany
Due to their catalytic, adsorptive and exchange properties aluminium-free layered silicate hydrates are interesting supplements to the well-known crystalline porous zeolites and alumophosphates. To create active sites Cerium ions were introduced into the interlayer space of metal silicate hydrates by an ion exchange process. A Ce/Na ion exchange was carried out with a 0.1N Ce(NO3)3-solution at room temperature. Two types of air dried Ce-containing layered silicates, ilerite and magadiite, were analysed by XANES and EXAFS spectroscopy at the Ce LIII-edge. Both valence states Ce3+ and Ce4+ have been detected but Ce3+ dominated at all. The ratio of Ce4+ /Ce3+ at ilerite was larger than that for magadiite. This result leads to the conclusion, that the local order must be higher around cerium in the ilerite.
© EDP Sciences 1997