Lanthanum effect on the textural and structural properties of γ-Al2O3 obtained from Boehmite

gamma-Al2O3-lanthanum supports (1, 10 and 20 wt.% La) were prepared by the impregnation of Boehmite with La(NO3)3*6H2O. According to the lanthanum content, the BET area diminishes from 220 to 122 m2/g. X-ray diffraction spectra showed gamma-Al2O3 in the 1 wt.% La sample, while in the 10 and 20 wt.% La specimens, amorphous alumina was detected; the formation of lanthanum-aluminate or lanthanum oxide was not observed. RMN (Al27RMN-MAS) spectra showed that the relative abundance of aluminum in tetrahedral symmetry stabilizes the gammaAl2O3 phase. FTIR-pyridine spectra show a diminution of Lewis acidity with the lanthanum content.