HYDROGENATION OF SUNFLOWER OIL UNDER SUPERCRITICAL CONDITIONS

M. PIQUERAS; M. FERNÁNDEZ; S. BOTTINI; D. DAMIANI

Rio de Janeiro, Brasil

Congreso; 2nd Mercosur Congress on Chemical Engineering, 4th Mercosur Congress on Process Systems Engineering; 2005

  Abstract. The good solvent, heat and mass transfer properties of supercritical fluids make them an excellent reaction medium for hydrogenation processes. The present work presents a comparative study of the hydrogenation of sunflower oil at homogeneous and heterogeneous supercritical state and under conventional gas-liquid conditions, in the search of improved cis/trans selectivity.  For each operating condition, the pressure-temperature phase envelope of the ternary system hydrogen + propane + sunflower oil was determined using a group contribution equation of state (GC-EOS). To assure homogeneous operation, the working temperature and pressure should lie outside the phase envelope of the reactive mixture. Compared to the conventional gas-liquid hydrogenation, two-liquid and homogeneous supercritical runs showed a greater progress of the reaction, velocities two orders of magnitude higher and a 70% increase in selectivity towards the cis isomers. Besides, it should be emphasized that at supercritical conditions the reaction occurs at lower temperatures, where the catalyst is not active in the conventional gas-liquid operation. The conditions that ensure supercritical operation and removal of mass transfer limitations affect reaction rates and selectivity to mono-unsaturated and saturated triglycerides.