Effect of Surface Acidic and Basic Properties of the Supported Nickel Catalysts on the Hydrogenation of Pyridine to Piperidine
Effect of Surface Acidic and Basic Properties of the Supported Nickel Catalysts on the Hydrogenation of Pyridine to Piperidine
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DOI：
10.1021/jp402238q
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发表时间：
2013-05
影响因子：
3.7
通讯作者：
Jie Zhao;Hui Chen;Jun Xu;Jianyi Shen
中科院分区：
文献类型：
--
作者：
Jie Zhao;Hui Chen;Jun Xu;Jianyi Shen
研究了Ni/Al2O3、Ni/MgAlO和Ni/MgO催化剂对吡啶加氢制哌替啶的催化作用。采用微量热吸附法和红外光谱法研究了催化剂对CO、H2、吡啶和哌啶的吸附。结果表明，碱性载体（MgO）增加了Ni的表面电子密度，增加了CO在Ni上的吸附热，同时减弱了H-Ni的强度，这可能是导致Ni/MgO对吡啶加氢活性降低的原因。相反，酸性载体（Al2O3）导致表面金属Ni缺乏电子，增强了对H2和吡啶的吸附，从而有利于吡啶的加氢。此外，虽然哌啶是比吡啶更强的碱，但吡啶对Ni的吸附比哌啶更强，这表明吡啶的富电子芳环可能参与了吡啶在Ni上的吸附，有利于在缺电子表面进行吸附。
Ni/Al2O3, Ni/MgAlO, and Ni/MgO catalysts were studied for the hydrogenation of pyridine to piperidine. Microcalorimetric adsorption and infrared spectroscopy were used to study the adsorption of CO, H2, pyridine, and piperidine on the catalysts. It was found that the basic support (MgO) increased the heat of adsorption of CO on Ni, due to the increased surface electron density of Ni, while weakened the strength of H–Ni, which might be a reason for the decreased activity of Ni/MgO for the hydrogenation of pyridine. In contrast, the acidic support (Al2O3) caused the electron-deficient surface metallic Ni that enhanced the adsorption of H2 and pyridine and thus favored the hydrogenation of pyridine. In addition, it was found that pyridine was more strongly adsorbed on Ni than piperidine although piperidine is a stronger base than pyridine, indicating that the electron-enriched aromatic ring of pyridine might be involved in the adsorption of pyridine on Ni, which was favored on the electron-deficient surface ...