Preparation and catalysis of polymer-stabilized NiB catalysts on hydrogenation of carbonyl and olefinic groups

PVP-stabilized NiB catalysts were prepared using the chemical reduction method with NaBH4, dissolving the water-soluble polymer of polyvinylpyrrolidone (PVP) in the precursor salt solution as a protective reagent. The PVP-NiB catalysts were characterized and examined for their catalysis on the hydrogenation of furfural, crotonaldehyde and citral. PVP polymer could adsorb on the nano-particles of NiB via a weak coordination bonding and stabilize it; a molecular weight of PVP of about 10,000 was suitable, and the optimal quantity of PVP (PVP/Ni) in the salt solution for preparing catalysts was around 20. The PVP-NiB samples were characterized by XRD as an amorphous structure and by TEM with a particle size distribution in the range of 3-5 nm. On catalysis, the PVP-NiB catalyst was significantly more active and slightly more selective than NiB for hydrogenating furfural to furfuryl alcohol and crotonaldehyde to butyraldehyde. A good yield of citronellal, about 90%, could be obtained by reducing citral in cyclohexane at a low reaction temperature of 50 °C over the PVP-NiB catalyst.