CO2-Enhanced Aqueous Extraction for Benign Separation of Reaction Products

Georgia Tech Research Corporation, Atlanta GA

Investigators

Abstract

Eckert, Charles A., et al. GA Tech Res Corp - GIT "CO2 Enhanced Aqueous Extraction for Benign Separation of Reaction Products" Separation and product purification are crucial for environmentally benign and economically attractive chemical processes. In this project, it will be shown that the thermodynamic properties of CO2 can modify phase boundaries and distribution coefficients to provide benign and efficient separation of reaction products and recycle of homogeneous catalysts. These processes will prevent pollution both by making fewer undesirable side products as well as by reducing water and energy needed for catalyst recycle. CO2 is miscible with most organics but virtually immiscible with water; also it is a powerful antisolvent in the organics. It has often been used in this manner for particle production or for fractional crystallization, but these applications require a saturated solution. The PIs propose to use it in conjunction with aqueous extraction to enhance recovery from more dilute organic solutions. The system proposed here can operate effectively even in dilute solutions. The PIs will show that systems containing water plus an organic where the addition of CO2 will result in significant absorption of CO2 into the organic only. This can achieve phase separation of a miscible organic/water mixture, or change drastically distribution coefficients in a two-phase organic/water system. As such this makes possible reactions between hydrophobic and hydrophilic moieties, with facile separation and purification after reaction. In addition it provide for benign recycle of catalysts which may be expensive and/or toxic. This research will show the advantages of novel solvent systems and will develop the thermodynamic data and phase equilibrium correlations needed to implement these systems. Broader Impact: The group proposing this work is a diverse joint Chemical Engineering - Chemistry team with extensive industrial partners. This format is especially advantageous for both multidisciplinary education and for technology transfer. The results will be both the education of superior chemical/environmental scientists and engineers, as well as amelioration of substantial pollution by current and future solvent-based processes.