Catalyst preparation and support effects for triglyceride hydrogenation over supported nickel

Nickel catalysts have been prepared by impregnation and precipitation methods on silica and charcoal. Metal loadings were in the range 1–40% w/w Ni on the support. The catalysts were investigated by temperature programmed reduction (TPR) and subsequently reduced in the temperature range 200–500°C. Metal surface areas were measured via H 2 and CO chemisorption and limited studies of the catalysts were carried out using X‐ray photon spectroscopy (XPS), X‐ray diffraction (XRD) and transmission electron microscopy (TEM) to determine the chemical and physical state of the nickel after reduction. Reduced catalysts were employed for triglyceride (soya bean oil) hydrogenation (1 atmos H 2 , 160°C) in a stirred reactor (1000 rpm) and reaction rates (catalyst activity) and product distributions were determined. Charcoal supported catalysts were active and zero valent nickel was detected after reduction. However, surface areas were variable, the performance of such catalysts being affected by pore effects, agglomeration and possibly nickel–charcoal interaction. Silica supported precipitated catalysts were of relatively high activity and metal surface if methanol washed before activation and inactive (irreducible) if only water washed. Although silica supported precipitated catalysts were more active per unit weight of metal than charcoal supported counterparts, they were less active per unit metal area and gave rise to greater trans‐acid production. This may be due to triglyceride molecules excluding hydrogen from small nickel crystallites.