Study of nickel catalysts supported on Al2O3, SiO2 or Nb2O5 oxides
Study of nickel catalysts supported on Al2O3, SiO2 or Nb2O5 oxides
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DOI：
10.1016/j.molcata.2005.07.013
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发表时间：
2005-12
影响因子：
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通讯作者：
A. Jasik;R. Wojcieszak;S. Monteverdi;M. Ziolek;M. Bettahar
中科院分区：
文献类型：
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作者：
A. Jasik;R. Wojcieszak;S. Monteverdi;M. Ziolek;M. Bettahar
我们使用简单 (SIM) 或 EDTA 双浸渍 (DIM) 方法研究了负载在 Al2O3、SiO2 和 Nb2O5 氧化物上的镍经典催化剂。非经典催化剂是通过在 353K 的肼水溶液中预处理 SIM 或 DIM 镍前体而获得的。通过 H2 吸附、H2-TPR、异丙醇分解和 FTIR 测量对催化剂进行了表征。它们已在苯的气相加氢中进行了测试。结果表明，载体表面酸度顺序为：SiO2<Al2O3<Nb2O5。由于存在不同的金属-载体相互作用强度，催化剂表现出不同的镍形态。因此，还原性、表面或氢化性质随着载体的性质或制备方法而变化。使用似乎与镍相互作用较少的二氧化硅载体获得了最佳性能。当使用氧化铌作为基质时，金属-载体相互作用最高。由于非常强的金属-载体相互作用，浸渍在氧化铌上的镍根本没有活性。研究了还原条件下肼水溶液与催化剂的相互作用。结果表明，肼与镍形成稳定的络合物，而其吸附在载体上的强度取决于氧化物的性质。
We have studied nickel classical catalysts supported on Al2O3, SiO2and Nb2O5oxides, using simple (SIM) or EDTA-double impregnation (DIM) methods. Non-classical catalysts were obtained by pretreatment of the SIM or DIM nickel precursors in aqueous hydrazine at 353K. The catalysts were characterized by H2-adsorption, H2-TPR, isopropanol decomposition and FTIR measurements. They have been tested in the gas phase hydrogenation of benzene. The results obtained show that the support surface acidity order was: SiO2<Al2O3<Nb2O5. The catalysts exhibited various nickel species due to the existence of various metal–support interaction strengths. As a consequence, the reducibility, surface or hydrogenating properties changed as a function of the nature of the support or method of preparation. The best performances were obtained with the silica support which seemed to interact less with the nickel. The metal–support interactions are highest when niobium oxide is used as the matrix. Ni impregnated on niobia was not active at all, due to very strong metal–support interactions. The interaction of aqueous hydrazine with the catalyst in the reduction conditions was examined. It was shown that hydrazine formed stable complexes with nickel, whereas it adsorbed on the support with a strength depending on the nature of the oxide.