Catalizadores estructurados en la hidrogenación de aceites vegetales

SANCHEZ J.; TONETTO G.; DAMIANI D.

Valle Hermoso Córdoba Argentina

Jornada; I Reunión Interdisciplinaria de Tecnología y Procesos Químicos; 2008

The hydrogenation of vegetable oils is an important process in the food industry to produce fats and oils with desirable melting properties and improved stability against oxidation. A new trend is to use palladium instead of nickel in the traditional processes. The purpose is to reduce the formation of trans-isomers during hydrogenation. The much higher price of the noble-metal catalyst has to be compensated by the repeated use of the catalyst. This can be achieved by using monolithic catalysts. The use of a monolithic catalyst also avoids the filtration step. This would represent a substantial reduction in the hydrogenation process cost, even if Pd is more expensive than Ni. Monolithic catalysts were prepared using Fecralloy and cordierite (350 and 400 cpsi, respectively) as substrate. An aqueous slurry of a Pd/Al2O3 catalyst with a 34 wt.% solids content was used for washcoating the monoliths. The resulting surfaces were characterized by X-ray diffraction, N2 sorption and scanning electron microscopy. The samples were studied in the partial hydrogenation reaction of sunflower oil at 373K and 413kPa. In comparative tests, at equal conversion and operation conditions, the structured catalysts displayed minor trans-isomer formation compared with the powder Pd/Al2O3 slurry catalyst. This is explained in terms of differences in the liquid/solid mass transfer. The monolithic catalyst was used in three subsequent hydrogenation batches (without in-between treatment). The ceramic monolith did not show changes in activity or selectivity. For the metallic monolith, a partial deactivation was observed (10%) and it was attributed to a loss of catalytic material. The present work demonstrates that the use of monolithic catalysts in the hydrogenation of vegetable oils is a viable and economically attractive alternative to the slurry process currently used at industrial level.