氢气高温还原制备的负载型镍基催化剂用于苯酚加氢的性能

通过等体积浸渍法分别将Ni(NO₃)₂、NiCl₂、NiSO₄ 3种镍前体浸渍于A1₂O₃或SiO₂载体上,然后通过H₂高温还原法制备了负载型镍基催化剂,考察了镍前体、载体种类、镍负载量、反应条件等对镍基催化剂苯酚加氢性能的影响。结果表明,对比3种镍前体,在H₂高温还原体系中Ni(NO₃)₂最容易被还原,制备的镍基催化剂苯酚加氢活性最高。SiO₂负载的镍基催化剂活性远高于γ-Al₂O₃催化剂。适宜的Ni负载量有助于活性组分的分散和催化活性的提高。镍基催化剂的苯酚加氢产物以环己醇为主,相对缓和的反应条件更容易生成环己酮。在非极性溶剂正庚烷或环己烷存在下,苯酚加氢反应速率远远高于极性溶剂水或乙醇存在下的结果,而且环己酮的选择性更高。

Performance of nickel supported catalysts on phenol hydrogenation

Nickel-based catalysts supported on γ-A1₂O₃ or SiO₂ from Ni(NO₃)₂, NiCl₂ or NiSO₄ as precursors were prepared with incipient technique and further reduced by H₂ at high temperature. Influence of nickel precursors, catalyst supports, nickel loadings and reaction conditions on the catalytic performance of phenol hydrogenation was investigated. Among three nickel precursors studied, Ni(NO₃)₂ was the most easily reduced by H₂ and the catalyst prepared displayed the best catalytic performance. It was shown that the nickel catalyst on SiO₂ exhibited higher performance than that on γ-Al₂O₃. The reasonable nickel loading was helpful to active component dispersion and good catalytic performance. The main product on the nickel supported catalysts was not the cyclohexanone but the cyclohexanol, and yet, the selectivity of cyclohexanone could be increased under the modest reaction conditions. The reaction rate or the cyclohexanone selectivity could be improved in nonpolar solvents like heptane or cyclohexane compared to that in polar solvents, like alcohol or H₂O.