STPI: Supercritical CO₂ processes

Leader: Séverine Camy

Supercritical CO₂ as a substitute for organic solvents

The activities of this theme are centered around the substitution of organic solvents by supercritical CO₂ for the development of clean reaction and separation processes. The experimental and theoretical study of the thermodynamic behavior of high pressure mixtures is the generic tool to optimally  implement these processes.

Extraction pilot 25 L -70 MPa (CRITT GPE).

A scientific approach where  modeling is coupled with experimentation

A mature activity

The problems posed by the use of supercritical CO₂ as a separation or purification solvent continue to be the subject of research taking the form of participation in ANR projects or supervision of theses. A significant fact over the past period is the extension of the field of investigation of this group, which today goes from modeling the operation (with a view to its extrapolation on an industrial scale) to characterizing the properties of products obtained. In particular, collaboration with the Faculty of Pharmaceutical Sciences in Toulouse now makes it possible to study the influence of process conditions on the biological activities of the CO2 extracts (antioxidants, anti-cancer…). The approach was applied both to the extraction of essential oils and to the recovery of lipids contained in yeasts (ANR-PNRB Lipicaero 2007-2010) or micro-algae (BQR Algoval project). The level of maturity in the field of extraction combined with our know-how on experimental devices is sufficiently high now  to allow a significant number of technology transfer operations to SMEs / SMIs through a collaboration with the specific transfer tool present in  the laboratory, the CRITT Process Engineering.

New fields of applications

The use of supercritical CO₂ as a reaction solvent for the development of clean chemistry is now  a strong activity of the group’s research. In particular, the current period saw the completion of a thesis and then a research contract with the company SANOFI Aventis concerning the implementation of a synthesis of pharmaceutical intermediary using the  Friedel-Crafts reaction in a continuous mode. In this project, the aim was to meet a triple challenge: substitution of the organic solvent with CO₂, transition from discontinuous mode to continuous mode and change in the nature of the catalyst (homogeneous to heterogeneous). In addition, the team is continuing its research in the field of chemistry in / with CO₂ through work on organic carbonation (synthesis of dimethyl carbonate) and mineral (concrete aggregates).

Directly linked to the other themes of the department

New interactions: The 2009-2014 period was marked by the start of an activity concerning the implementation of the fractionation of liquid mixtures by supercritical CO₂ in the continuous mode in a counter current packed contactor. Unlike the treatment of solids with supercritical CO₂, liquid fractionation is currently the subject of little industrial development due in part to a greater complexity of operability. The study was approached as part of an intra-departmental collaboration with the theme “Reactive Separations” for aspects relating to fluid-liquid flows on packings. The study now relates to the evaluation of the performance of these contactors by experimental study and by simulation of the mass transfer in the case of model mixtures. Understanding and mastering this type of process has been the subject of several projects submitted to the ANR and to participation in congresses.