Preparation of nickel nanoparticles with different sizes and structures and catalytic activity in the hydrogenation of p-nitrophenol

Spherical nickel nanoparticles with different sizes and different crystal structures were prepared by reducing nickel oxalate with hydrazine hydrate in the presence of PEG 200, PEG 6000, Tween 40, Tween 80, and sodium dodecyl sulfonate as organic modifiers. The organic modifiers with different functional groups play an important role in deciding the size and structure of the nickel nanoparticles. As compared to the conventional RANEY® Ni catalyst, all the as-prepared nickel nanoparticles showed high catalytic activity and selectivity in the hydrogenation of p-nitrophenol to p-aminophenol. The catalytic activities of the as-prepared nickel nanoparticles generally increased with decreasing the particle size. The crystal structure of nickel nanoparticles also had an important impact on the catalytic activity.