Phase Equilibrium Engineering of supercritical extraction, fractionation and reactive processes

N. GAÑAN; P. HEGEL; S. PEREDA; E. A.BRIGNOLE

Marsella

Simposio; 14th European Meeting on Supercritical Fluids; 2014

The chemical and pharmaceutical industries have a key role in global economic development. However, the environmental impact of this industrial sector could impair its future development. Green Chemistry principles are calling for the use of renewable resources, less waste and environmentally friendly solvents (EFS). Among EFS supercritical fluids (SCF) have proved their important role. A field that has numerous SCF applications is that related to natural products processing, which is growing driven by the fact that biomass is renewable and nature can produce many complex molecules in a highly efficient way. The design of the phase conditions in supercritical processes is directly tied to the process goal. In the case of fractionation or extraction, an heterogeneous phase behavior is required over the whole range of process compositions; the opposite may be required in the case of reactive processes where homogeneous conditions are favored to avoid mass transfer limitation that hinders the reaction rate. In both cases, the nature of the mixture to deal with and the process goal are critical in the selection of SCF solvent and in the selection of the process operating variables (pressure, temperature and composition). In this work Phase Equilibirum Engineering principles are applied to the design of the phase conditions in extraction, fractionation and reacting systems for a wide range of natural products. For this purpose thermodynamic models, tuned to the particular systems of interest, are used to predict the general diagrams of univariant lines for mixtures of key binary components, to predict the mixtures critical points and phase envelopes. On this basis a strategy for the design of optimum operating conditions for supercritical processes is developed. This approach is illustrated with a case study of fractionation of monoglycerides obtained as by products of supercritical transesterification of vegetable oils.