COSMO-RS Aided Design of New, Natural Deep Eutectic Solvents for CO2 Capture

CO2 capture from power plants is regarded as an effective midterm solution to reduce anthropogenic greenhouse gas emissions. In the case of an integrated gasification combined cycle (IGCC) power plant with precombustion CO2 capture, the product out of the water–gas shift (WGS) reactors is sent for CO2 separation. Physical absorption using hydrophobic absorbents with low volatility, low viscosity, and high CO2 solubility is a promising technique.

In a recent paper, hydrophobic deep eutectic solvents (DESs) have been designed as effective physical solvents for CO2 capture by using the conductor-like screening model for real solvents (COSMO-RS). Researchers from the TU Eindhoven proved that the ADF-COSMO-RS calculations could reliably predict the CO2 solubilities in various pure compounds and binary solvents. Through this computational screening, 38 naturally hydrophobic compounds with a high CO2 affinity have been selected to prepare new DESs. The possibilities for any two components to form a DES are evaluated using their predicted individual activity coefficients through COSMO-RS calculations. The CO2 solubility in the theoretically feasible DESs is predicted, and the promising DESs like vanillin-4-oxoisophorone (1:3) and methyl salicylate-4-oxoisophorone (1:1) are screened out. The new DESs are experimentally identified to be very promising for precombustion capture, showing comparable CO2 solubility and viscosity to the well-known, conventionally used Selexol solvent.

The researchers also showed the quantitative structure–property relationship (QSPR) models could accurately predict the density of the non-ionic DESs, with average prediction error less than 10%. Moreover, the viscosity of DESs can also be predicted with QSPR models using COSMO-RS based descriptors.

These findings demonstrate that ADF-COSMO-RS is a strong tool to reduce the time and experimental resources to develop new solvents for gas separation applications.

COSMO-RS solvent selection deep eutectic solvents CO2 capture

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K. Xin, F. Gallucci, M. van Sint Annaland, Development of Natural Hydrophobic Deep Eutectic Solvents for Precombustion CO2 Capture, ACS Sustainable Chem. Eng. 10, 15284-15296 (2022)

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