Improvement of carbon dioxide absorption technology using conductor-like screening model for real solvents (COSMO-RS) method

Abstract

Solvents with better properties than the ones presently in use for carbon dioxide (CO2) absorption processes would make absorption technology more attractive for large scale reduction of CO2 emissions. In this work, more than 2000 solvents comprising of four groups were considered for screening. The groups are: amine solvents (primary, secondary, tertiary, sterically hindered, multiple amines and physical solvents), neutral solvents, mixed solvents and ionic liquids (ILs). Conductor-like screening model for real solvents (COSMO-RS) model was used in predicting thermodynamic properties, such as Henry’s constant, octanol-water partition coefficient, solubility in water and vapour pressure of all the solvents. The best two solvents from each of the four groups were selected based on the criteria of high capacity and high selectivity of the solvent in comparison to a benchmark solvent (BS), that is, [methyl-diethanolamine (MDEA) + Piperazine]. All the eight selected solvents were found to be environmental friendly having very low octanol-water partition coefficient KOW, which is far less than the hazard limit of 10,000. Out of the eight selected solvents, sulfolane (S), (NMP + S), and ([N,N,N,N,N-Pentamethyl-N-IsopropylGuanidinium][Br]) were recommended for having better properties than the BS. Key words: Henry’s constant, conductor-like screening model for real solvents (COSMO-RS), carbon dioxide absorption, capacity, selectivity.