ANIR SPECTROSCOPIC STUDY OF THE REACTION KINETICS OF SURFACE CARBONYL AND FORMATE SPECIES ON SUPPORTED O_s CATLYST

Chromium-containing Y zeolite has been prepared by ion exchange in the solution of Cr(NO₃)₃. After dehydration and oxidation EPR spectra show that there are two different coordination structures around chromium cations:one is located in β cage with elongated tetrahedral symmetry and another in supercage with pyramidal symmetry. The combined results of XPS and EPR reveal that the chromium cations migrated from the locations near external surface into the internal cages under the induction of NH₃, while the pyridine and water have the opposite effect on the migration or chromium cations in Y zeolite.