Sunflower oil hydrogenation on Pt catalysts: Comparison between conventional process and homogeneous phase operation using supercritical propane

Abstract

The hydrogenation of sunflower oil on TiO 2 supported by Pt catalysts was studied. The Pt/TiO 2 catalyst was modified: (a) with K and (b) by high temperature reduction treatment, in order to observe its influence on the activity and the cis-isomers selectivity. The catalysts were characterized by atomic absorption, H 2 chemisorption, TPR and XRD. The hydrogenation of edible oils at conventional conditions is diffusion controlled. The addition of propane as supercritical (SC) solvent allows to perform the reaction in a homogeneous phase in contact with the solid catalyst. A significant increase in the reaction rate of the homogeneous system was observed. Regarding selectivity, the formation of trans-isomers was higher in the reaction under conventional conditions, whereas the production of saturated compound was favored in the homogeneous operation. Pt-K/TiO 2 and Pt/TiO 2 catalyst presented a similar TON, although the cis-isomer selectivity increased with the alkali addition. This behavior is explained in terms of a chemical modification of the noble metal.