Density Functional Theory Study on the Cholinium Dihydrogenphosphate Ionic Liquid for Acid Gas Removal

Cholinium dihydrogenphosphate is proposed as a new ionic liquid for acid gas removal from flue gases. A theoretical study using density functional theory and COSMO-RS approaches was carried out to get a nanoscopic picture of the interaction between the involved ions and CO2 and SO2 molcules. This computational approach allowed us to infer the main molecular features controlling gas absorption, such as preferential interaction sites, chemical potentials, binding energies, and topological properties of ion-gas interactions through the Atoms-in-a-Molecule approach. The results reported herein show that the theoretical approach allowed us to infer the most remarkable features of acid gas capture by ionic liquids, and thus it could be used for improving the ability of ionic liquids for acid gas capture purposes through molecular engineering of the ions' properties.