Acid-base properties of alumina-supported rare-earth oxides (Ln/Al2O3; Ln =
La, Ce, Eu, Tb, and Yb) were investigated with alpha -pinene isomerization
, 2-butanol decomposition, and temperature-programmed desorption and FTIR t
echniques. The structural characterization was carried out by means of XRD,
Raman, and XAFS spectroscopies. Differences in the catalyses, acid-base pr
operties, and structures of Ln/Al2O3 catalysts because of loaded elements a
nd the amounts were discussed. The addition of a lanthanoid atom (Ln) to ga
mma -Al2O3 poisons both the original base and acid sites of gamma -Al2O3 an
d generates new-type Lewis acid site. In a series of Ln/Al2O3 catalysts, 0.
2-0.5 mmol of Yb/Al2O3 exhibited the highest activity for alpha -pinene iso
merization. The supported Yb species form Yb-O-Al linkage which acts as a L
ewis acid. The local structure around Yb and a generation mechanism of acid
ic property are analogous with Yb/Al2O3 and Yb/SiO2.