Effect of alkali leaching on the surface structure of Ni3Al catalyst

Abstract The surface structure of the alkali-leached single-phase Ni 3 Al powder was investigated by X-ray diffraction, BET (Brunauer–Emmett–Teller) surface area analysis, electron microscopy, X-ray photoelectron spectroscopy, and temperature-programmed reduction. It was found that fine Ni particles of several nm in diameter were formed on the outer surface layer of the Ni 3 Al powder after the alkali leaching process. The surface of the Ni particles was covered with a thin layer of Ni oxides and hydroxide, Ni 2 O 3 , NiO and Ni(OH) 2 , and these Ni oxides and hydroxide can be easily reduced by hydrogen to the metallic nickel that is catalytically active. The inside of the Ni 3 Al powder remained as the original Ni 3 Al ordered structure after alkali leaching. Having heat resistant properties, the Ni 3 Al phase can serve as a support of the fine Ni particles and provide the structural and thermal stabilities to the fine Ni particles.