Structural characteristics of a Ni-Ag magnetic catalyst and its properties in soybean oil hydrogenation

Ni-Agx/PVP-DB-171/SiO2/Fe3O4 magnetic nanoparticle (NP) catalysts were prepared using PVP-DB-171/SiO2/Fe3O4 magnetic NPs as a support. The prepared catalysts were characterized via X-ray powder diffraction, scanning electron microscopy/energy dispersive X-ray spectroscopy, vibrating sample magnetometer, inductively coupled plasma-optical emission spectroscopy and N2 adsorption-desorption isotherm. The results indicate that the dispersion of nickel on the PVP-DB-171/SiO2/Fe3O4NP support was improved by incorporating Ag as a promoter. The optimal Ni-Ag molar ratio was 0.15. Soybean oil hydrogenation was carried out with Raney nickel, Ni/PVP-DB-171/SiO2/Fe3O4 and Ni-Ag0.15/PVP-DB-171/SiO2/Fe3O4 catalysts. The results show that the Ni-Ag0.15/PVP-DB-171/SiO2/Fe3O4 magnetic NP catalyst has the highest activity and stability. The use efficiency of the catalyst decreased to 60% after 8 cycles. The content of trans fatty acids in hydrogenated soybean oil decreased to 10.4% after 90 min of hydrogenation. Compared with filtration or centrifugation, the magnetic NP catalyst can be quickly and cost-efficiently separated by applying an external magnetic field.