Nanocrystalline a-Al 2 O 3 and Ni-modified a-Al 2 O 3 have been prepared by sol-gel and solvothermal methods and employed as supports for Pd catalysts. Regardless of the preparation method used, NiAl 2 O 4 spinel was formed on the Ni-modified a-Al 2 O 3 after calcination at 1150 8C. However, an addition of NiO peaks was also observed by X-ray diffraction for the solvothermal-made Ni-modified a-Al 2 O 3 powder. Catalytic performances of the Pd catalysts supported on these nanocrystalline a-Al 2 O 3 and Ni-modified a-Al 2 O 3 in selective hydrogenation of acetylene were found to be superior to those of the commercial a-Al 2 O 3 supported one. Ethylene selectivities were improved in the order: Pd/Ni-modified a-
As revealed by NH 3 temperature program desorption studies, incorporation of Ni atoms in a-Al 2 O 3 resulted in a significant decrease of acid sites on the alumina supports. Moreover, XPS revealed a shift of Pd 3d binding energy for Pd catalyst supported on Ni-modified a-Al 2 O 3 -sol-gel where only NiAl 2 O 4 was formed, suggesting that the electronic properties of Pd may be modified.