Molecular Simulations of the Thermophysical Properties of Polyethylene Glycol Siloxane (PEGS) Solvent for Precombustion CO2 Capture

The thermophysical properties for neat polyethylene glycol siloxane solvent (PEGS) along with CO2, H2, H2O, and H2S gas absorption in PEGS at 298–373 K were investigated via molecular simulations. The predicted neat PEGS density, heat capacity, surface tension, and CO2 and H2 solubilities in PEGS solvent agree reasonably well with the experimental data, with typical differences of 0.8–20%, while the predicted PEGS solvent viscosity is 1.7–2.5 times larger than the experimental data. Gas solubility in PEGS at 298 K decreases in the following order, H2O (31000) > H2S (230) > CO2 (33) > H2 (1), which follows the same order as the gas–PEGS interaction. In contrast, gas diffusivity in PEGS at 298 K decreases in an opposite way, H2 (1) > CO2 (0.22) ≈ H2S (0.12) > H2O (0.018). The numbers in parentheses are the corresponding values relative to H2. Compared to the widely studied poly(dimethylsiloxane) (PDMS) solvent, PEGS is more hydrophilic due to its stronger interaction with H2O and fewer branched −CH3 groups,...