Preparation of nano-sized nickel and effect of preparing conditions on catalytic hydrogenation of p-nitrophenol

A series of nano-sized nickel catalysts were prepared by an improved chemical reduction method. The effects of the preparation conditions on the catalytic activity of the nano-sized nickel were examined in the hydrogenation of p-nitrophenol to p-aminophenol. The results showed that the catalytic activity of the nano-sized nickel first increased and then changed slightly with the increase of the amount of N₂ H₄ · H₂O, with the optimum at n (N₂H₄ · H₂O) : n (Ni²⁺) = 1.5 : 1; the catalytic activity first increased and then decreased with the increase of the amount of NaOH, with the optimum at n(NaOH) : n(Ni²⁺) = 1.5 : 1; the catalytic activity first increased and then decreased with the increase of the reaction temperature, with the optimum at 76 °C; the optimum reaction time was 2 min and the catalytic activity decreased gradually with the increase of the reaction time. The particle sizes of the nano-sized nickel prepared under the optimum conditions were about 25 nm and the corresponding hydrogenation rate was about 19.4 mmol/(min · g).