Prediction of binding bond energy between phosphorous-based ionic liquids and CO2. Assessment of the CO2-anion interactions

The absorption of carbon dioxide (CO2) in phosphorous-based ionic liquids was studied theoretically by the molecular modeling ab initio density functional theory (dispersion-corrected B3LYP) and second-order Moller-Plesset perturbation methods. Several types of phosphate-and phosphite-based anions were employed and the calculation results were compared with recent published papers. The interaction energy between CO2 and anion, following the result of Bhargava and Balasubramanian, was calculated in order to have a better understanding on the effect of different functional groups on the interaction between CO2 and anion. The computational results indicated that the molar volume of the anion molecules played an important role on the absorption mechanism of CO2 due to the CO2-philicity of carbonyl and alkyl groups.