Hydrogenation of sunflower oil over different palladium supported catalysts: Activity and selectivity

Six palladium catalysts were prepared using different precursors (palladium acetylacetonate, palladium nitrate and tetraamminepalladium nitrate) and supports (α-Al2O3, γ-Al2O3, ZSM-5, and MCM-22). The samples were characterized by atomic absorption spectroscopy, N2 adsorption isotherms, XRD, H2 chemisorption, transmission electron microscopy and temperature programmed reduction. The activity and selectivity of the catalysts were investigated in the hydrogenation of sunflower oil and compared to a commercial Ni catalyst.Pd catalysts showed a higher activity, similar trans-isomer formation, and were more selective towards monoene formation than Ni catalysts. On the other hand, under the studied operating conditions, the different supports did not improve significantly the selectivity or the activity of the reaction.The γ-alumina supported Pd catalyst, with a metal loading of 0.78 wt% and a 60% dispersion, showed a specific activity higher than the other Pd catalysts. For the same double bond conversion, this sample originated a slightly lower amount of total trans-isomers than the Ni catalyst, but it produced less saturated compound and was more selective towards monounsaturated fatty acid formation.