Synthesis and Catalytic Properties for Phenylacetylene Hydrogenation of Silicide Modified Nickel Catalysts

Interstitial silicide-modified nickel, with high selectivity in some hydrogenation reactions, had been produced by dissolving silicon atoms into the nickel lattices. The metallic nickel was obtained by reducing the as-prepared high surface area NiO, followed by modification of the bulk nickel through silification of silane/H2 at relatively low temperature and atmospheric pressure. The as-prepared materials were characterized by X-ray diffraction, magnetic measurements, X-ray photoelectron spectroscopy, transmission electron microscopy, energy dispersive X-ray spectroscopy, and temperature-programmed reduction. The results show nickel silicide formation involves the following sequence as a function of increasing temperature: Ni (cubic) → Ni2Si (orthorhombic) → NiSi (orthorhombic) → NiSi2 (cubic). The insertion of Si atoms into the interstitial sites between Ni atoms resulted in a significant change in the unit cell lattice of nickel. All of the silicide-modified nickel materials were ferromagnetic at room ...