Abstract :
Yb2+ and/or Yb3+ amide species fixed in potassium-exchanged zeolite were evacuated at various temperatures. The local structures of these Yb species were analyzed by Yb L3-edge EXAFS. For the mixture of Yb2+ and Yb3+ species, a subtraction technique was applied to the EXAFS spectrum on the basis of quantitative results of an XANES analysis. EXAFS spectra clearly showed that the dispersion of Yb species changed drastically at around 500 K; from the highly dispersed state to the aggregated state. Such a structural change was closely correlated with the change of the catalytic properties of the Yb species.
