Effect Of Alkali Leaching On The Surface Structure Of Ni_3al Catalyst

摘要

The surface structure of the alkali-leached single-phase Ni_3Al powder was investigated by X-ray diffraction, BET (Brunauer-Emmett-Teller) surface area analysis, electron microscopy, X-ray photo-electron 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_3Al powder after the alkali leaching process. The surface of the Ni particles was covered with a thin layer of Ni oxides and hydroxide, Ni_2O_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_3Al powder remained as the original Ni_3Al ordered structure after alkali leaching. Having heat resistant properties, the Ni_3Al phase can serve as a support of the fine Ni particles and provide the structural and thermal stabilities to the fine Ni particles.