Alumina-supported rare-earth oxides characterized by acid-catalyzed reactions and spectroscopic methods

Yamamoto, T Tanaka, T Matsuyama, T Funabiki, T Yoshida, S

T. Yamamoto et al., Alumina-supported rare-earth oxides characterized by acid-catalyzed reactions and spectroscopic methods, J PHYS CH B, 105(9), 2001, pp. 1908-1916

44

INGLESE

Article

Physical Chemistry/Chemical Physics

JOURNAL OF PHYSICAL CHEMISTRY B

1520-6106 → ACNP

105

9

2001

1908 - 1916

ISI

1520-6106(20010308)105:9<1908:AROCBA>2.0.ZU;2-N

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.