Electron spin resonance studies of copper-exchanged Y zeolites. Part 2.—Interactions with CeIII ions inside the zeolite framework

Abstract

E.s.r. spectra are measured for Y zeolites exchanged with cerium and copper ions after several dehydration treatments. Comparison of the results with those obtained for Cu-exchanged zeolites shows differences in the intensity and stability of some of the copper (II) species. A scheme is proposed for interpretation of these results, based on the formation of oxygen-bridged structures with Ce^III and Cu^II ions in neighbouring S I′ positions. On the basis of this model, an explanation is given for the changes in Brönsted acidity and catalytic activity reported previously for the same samples.