Group 2, 3, and 13
element-doped
zirconium oxide catalysts M-ZrO2 (M = Mg, Sr, Y, La, Ce, Sm, Er, Yb, B, Al, Ga, In, and Tl; 5 mol%) were prepared by impregnation of each
metal salt aqueous
solution on amorphous
zirconium hydroxide, followed by calcination at 773 K. The M-ZrO2 samples were characterized by the catalytic performance of
2-butanol decomposition at 573 K, XRD, XANES and EXAFS spectroscopic techniques. Detailed analyses were performed herein for a series of Ga-ZrO2 with various doping amounts in the range of 1 - 60 mol%. The addition of Group 2 and 3 elements little influenced the catalytic performance of ZrO2 itself to promote
dehydration to produce
1-butene with 90% selectivity. Ga-ZrO2 and In-ZrO2 gave
methyl ethyl ketone as the main product via dehydrogenation. The doped Ga ion mainly existed inside the bulk of
zirconia by forming the GaxZr1-xO2 solid
solution up to 5 mol%. Highly doped species more than 10 mol% aggregated to form ε-Ga2O3. Each fraction forming the solid
solution and Ga2O3-like species was evaluated by XANES analysis.