漆原镍催化剂用于苯酚催化加氢

利用锌粉将NiCl₂液相还原制备漆原镍催化剂,考察了碱/酸活化方法、锌粉用量、还原温度、添加载体等条件下漆原镍催化苯酚加氢反应的性能。结果表明,锌粉还原的漆原镍催化剂可用NaOH或者乙酸活化处理,NaOH的效果优于乙酸。与不添加载体的催化剂相比,添加载体组分明显提高了金属镍的分散性和利用率。γ-Al₂O₃、CaCO₃、MgO均可作为漆原镍催化剂载体组分,而γ-Al₂O₃效果最好。还原剂锌粉用量、载体加入量过少或过多,都会造成催化剂活性降低,这与其影响金属镍的可接近性及分散性相关。无载体或加入载体的漆原镍催化剂均可在120~160 ℃催化苯酚加氢反应,主要产物为环己醇和环己酮,并以环己醇为主。

Hydrogenation of phenol over Urushibara Ni catalysts reduced by zinc powder

Urushibara nickel catalysts were prepared from aqueous NiCl₂ solution with zinc powder as a reducing agent and used in phenol hydrogenation. The effects of zinc powder amount, reduction temperature and pretreatment-activation method on the catalytic performance of Urushibara nickel in phenol hydrogenation was investigated. To inhibit the magnetic agglomeration of the pure nickel catalyst, γ-Al₂O₃, CaCO₃ and MgO were added as a support. The results indicated that the nickel catalysts obtained by zinc reduction can be pretreated and activated by NaOH or acetic acid solution, though the former is superior to the latter. The catalytic activity of Urushibara nickel is related to the amount of zinc used for the reduction. The nickel catalyst reduced at 100 ℃ with an n(Zn)/n(NiCl₂·6H₂O) ratio of 4.5 exhibits the highest hydrogenation activity. γ-Al₂O₃ as a support can promote the dispersion and sediment of the reduced nickel and alleviate the magnetic agglomeration. The Urushibara nickel catalysts are active for phenol hydrogenation at 120~160 ℃, with cyclohexanol and cyclohexanone as the main products; the conversion of phenol reaches 53%~66%, with the selectivity of 95.0%~96.0% to cyclohexanol.