Organometallic Preparation of Ni, Pd, and NiPd Nanoparticles for the Design of Supported Nanocatalysts

The preparation of bimetallic nanoparticles with controlled size, shape, and composition remains a difficult task, and reproducible methods are highly desired. Here, we report the codecomposition of Ni(cod)(2) and Pd-2(dba)(3) organometallic precursors in the presence of hexadecylamine (HDA) and hydrogen as an efficient approach to get size-controlled bimetallic nickel palladium nanoparticles. Presynthesized nickel palladium nanoparticles of different Ni/Pd ratios were further used for the preparation of supported catalysts by the sol-immobilization method onto a magnetic silica. The obtained supported catalysts were investigated in the hydrogenation of cyclohexene and compared to Ni and Pd monometallic catalysts. The catalysts prepared with a 1:9 Ni/Pd molar ratio achieved the highest initial turnover frequency > 50000 h(-1), providing higher activity than the pure Pd monometallic counterpart. This represents an important saving of noble metal. Moreover, the magnetic separation allows excellent separation of the catalyst from the liquid products without metal leaching and exposure to air, leading to an efficient recycling.