无机化学学报

Ni²⁺在γ-Al₂O₃上的分散状态及负载型Ni/γ-Al₂O₃催化剂的α-蒎烯加氢活性(英文)

Dispersion State of Nickel Ions on γ-Al₂O₃ and Catalytic Activity of Derived Nickel Catalysts for Hydrogenation of α-Pinene

作者	单位
任世彪	南京大学化学化工学院，介观化学教育部重点实验室，江苏省纳米技术重点实验室，南京 210093
邱金恒	南京大学化学化工学院，介观化学教育部重点实验室，江苏省纳米技术重点实验室，南京 210093
王春燕	南京大学化学化工学院，介观化学教育部重点实验室，江苏省纳米技术重点实验室，南京 210093
许波连	南京大学化学化工学院，介观化学教育部重点实验室，江苏省纳米技术重点实验室，南京 210093
范以宁	南京大学化学化工学院，介观化学教育部重点实验室，江苏省纳米技术重点实验室，南京 210093
陈懿	南京大学化学化工学院，介观化学教育部重点实验室，江苏省纳米技术重点实验室，南京 210093

摘要: 用X-射线衍射(XRD)、紫外-可见漫散射光谱(UV-Vis DRS)、程序升温还原(TPR)、CO化学吸附和微反测试等方法研究了Ni²⁺在γ-Al₂O₃上的分散状态和负载型Ni/γ-Al₂O₃催化剂的α-蒎烯加氢催化活性。结果表明，当Ni²⁺负载量远低于其在γ-Al₂O₃载体表面分散容量时，Ni²⁺优先嵌入载体表面四面体空位，随着Ni²⁺负载量的增加，嵌入载体表面八面体空位Ni²⁺的比例增大。由于八面体Ni²⁺易被还原为金属态Ni⁰，NiO/γ-Al₂O₃样品的还原度随Ni²⁺负载量的增加而大幅度地增加，经氢还原所得Ni/γ-Al₂O₃催化剂的CO吸附量和α-蒎烯加氢催化活性大幅度增加。对La₂O₃助剂的作用进行了研究，结果表明分散在γ-Al₂O₃上的La³⁺物种可阻止Ni²⁺嵌入γ-Al₂O₃表面四面体空位，增大了八面体Ni²⁺物种所占比例，提高了催化剂的还原度，故Ni-La₂O₃/γ-Al₂O₃催化剂催化活性高于Ni/γ-Al₂O₃催化剂。

关键词: Ni/γ-Al₂O₃ NiO/γ-Al₂O₃；分散状态；催化加氢； α-蒎烯

基金项目:

Abstract: The dispersion state of nickel ions on γ-Al₂O₃ and the catalytic hydrogenation activity of supported Ni/γ-Al₂O₃ catalysts have been studied by means of X-ray diffraction (XRD), UV-Vis diffuse reflectance spectroscopy (DRS), H₂ temperature-programmed reduction (TPR), CO chemisorption and microreactor tests. It has been shown that the supported nickel ions preferentially incorporate into the tetrahedral vacancies of γ-Al₂O₃ when Ni²⁺ loading is far below its dispersion capacity on γ-Al₂O₃. Increasing Ni²⁺ loading, the ratio of Ni²⁺ ions incorporated into the octahedral vacancies of γ-Al₂O₃ increases. Since the octahedral Ni²⁺ ions are easier to be reduced to the metallic state, the reduction degree of supported NiO/γ-Al₂O₃ sample increases greatly with Ni²⁺ loading, thus resulting in a great increase in the CO uptake and catalytic activity of Ni/γ-Al₂O₃ catalyst for hydrogenation of α-pinene. The promotional effect of La₂O₃ on the catalytic activity of the supported Ni/γ-Al₂O₃ catalyst has been studied as well. It has been suggested that the dispersed La³⁺ species on γ-Al₂O₃ may inhibit incorporation of Ni²⁺ ions into the tetrahedral vacancies of γ-Al₂O₃ and increases the ratio of octahedral Ni²⁺ ions to tetrahedral Ni²⁺ ions, and thus increases the reduction degree of the catalyst precursor. As a result, the Ni-La₂O₃/γ-Al₂O₃ catalyst shows higher catalytic activity than the Ni/γ-Al₂O₃ catalyst with the same nickel loading.

Keywords: NiO/γ-Al₂O₃ Ni/γ-Al₂O₃ dispersion state α-pinene catalytic hydrogenation

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任世彪,邱金恒,王春燕,许波连,范以宁,陈懿.Ni²⁺在γ-Al₂O₃上的分散状态及负载型Ni/γ-Al₂O₃催化剂的α-蒎烯加氢活性(英文)[J].无机化学学报,2007,23(6):1021-1028.

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