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

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• 作者：Xiao Chen ; Anqi Zhao ; Zhengfeng Shao ; Chuang Li ; Christopher T. Williams ; Changhai Liang
• 刊名：Journal of Physical Chemistry C
• 出版年：2010
• 出版时间：October 7, 2010
• 年：2010
• 卷：114
• 期：39
• 页码：16525-16533
• 全文大小：574K
• 年卷期：v.114,no.39(October 7, 2010)
• ISSN：1932-7455

文摘

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 temperature, and saturation magnetization values drastically decreased when Si is present. Silicide-modified nickel develops a thin silicon oxide layer during exposure to air, which can be removed by H₂-temperature programmed reduction. The as-prepared bulk silicide-modified nickel showed above 92% styrene selectivity in the hydrogenation of phenylacetylene under 0.41 MPa H₂ and at 50 °C for 5 h. In addition, only low conversions were obtained for styrene hydrogenation under the same hydrogen pressure and temperature for 50 min. These results indicate that these novel silicide-modified nickels are promising catalysts for the selective hydrogenation of unsaturated hydrocarbons.