Membrane processes in ScCO2 medium for economical supercritical processes – MemScCO2

Green chemistry principles lead to non-solvent or green solvent processes among which CO2 in sub or supercritical state (ScCO2) has been considered as an excellent choice for its modulable transport properties as density, viscosity diffusivity of compounds in ScCO2 and its good solvent power for non-polar compounds. However, even if use of ScCO2 as a solvent is promising from environmental and safety points of view, the energy costs of using high-pressure CO2 may discourage its use at industrial scale. As an example, the energy cost to recompress the CO2, from atmospheric pressure to 120 bars is around 160 kJ/kg of CO2: this energy is lost during the gas expansion to recover the products at atmospheric pressure. Research and development are thus needed in order to increase the arsenal of solutions to reduce energy and costs associated to the use of high-pressure CO2. The MemScCO2 project presents a strategy to decrease energy costs associated to the use of high pressure CO2 by using membrane processes.
Membrane processes are considered as energy-efficient technologies which allow a high selectivity for separation and allow the achievement of high levels of process intensification. Membrane processes can be used to concentrate the products before the recovery step from the ScCO2 using reverse osmosis or to extract the products from the ScCO2 without decreasing the CO2 pressure using membrane contactors. Purified ScCO2 is then recycled at high pressure allowing a reduction of the compression cost.
The aim of MemSCCO2 is to study the coupling of membrane processes with a ScCO2 extraction in order to evaluate energy gains by taking into account the specificities of both processes with a life cycle assessment approach. In the MemScCO2 project, we propose to extract carotene and lycopene as high added value products and vegetable oil as a low added value product from natural matrices and to couple this extraction to a membrane process in order to obtain a rentable extraction process by decreasing the environmental footprint and the energy consumption.