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Title: Molecular Simulations of the Thermophysical Properties of Polyethylene Glycol Siloxane (PEGS) Solvent for Precombustion CO 2 Capture

Abstract

Here, the thermophysical properties for neat polyethylene glycol siloxane solvent (PEGS) along with CO 2, H 2, H 2O, and H 2S gas absorption in PEGS at 298–373 K were investigated via molecular simulations. The predicted neat PEGS density, heat capacity, surface tension, and CO 2 and H 2 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, H 2O (31000) > H 2S (230) > CO 2 (33) > H 2 (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, H 2 (1) > CO 2 (0.22) ≈ H 2S (0.12) > H 2O (0.018). The numbers in parentheses are the corresponding values relative to H 2. Compared to the widely studied poly(dimethylsiloxane) (PDMS) solvent, PEGS is more hydrophilic due to its stronger interaction with H 2O and fewer branched –CH 3 groups, which in turn leads to fewer hydrophobic pockets. The CO 2/H 2 solubility selectivity in PEGS is largermore » than that in PDMS due to a stronger interaction with CO 2 in PEGS. Finally, it was found that CO 2 absorption in PEGS could significantly improve the CO 2–PEGS solution dynamics by 5–6 times, resulting in a decrease in solution viscosity and increase in diffusivity. These CO 2 absorption effects are due to solution volume expansion upon CO 2 absorption compared to the neat PEGS solvent volume and the possibility that CO 2 acts as a “lubricant” to decrease the solvent–solvent interaction.« less

Authors:
 [1];  [2];  [2];  [2];  [2]
  1. National Energy Technology Lab. (NETL), Pittsburgh, PA, (United States); AECOM, South Park, PA (United States); Univ. of Pittsburgh, Pittsburgh, PA (United States)
  2. National Energy Technology Lab. (NETL), Pittsburgh, PA, (United States)
Publication Date:
Research Org.:
National Energy Technology Lab. (NETL), Pittsburgh, PA, (United States)
Sponsoring Org.:
USDOE Office of Fossil Energy (FE)
OSTI Identifier:
1478188
Grant/Contract Number:  
FE0004000
Resource Type:
Accepted Manuscript
Journal Name:
Journal of Physical Chemistry. C
Additional Journal Information:
Journal Volume: 120; Journal Issue: 36; Journal ID: ISSN 1932-7447
Publisher:
American Chemical Society
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY

Citation Formats

Shi, Wei, Siefert, Nicholas S., Baled, Hseen O., Steckel, Janice A., and Hopkinson, David P. Molecular Simulations of the Thermophysical Properties of Polyethylene Glycol Siloxane (PEGS) Solvent for Precombustion CO2 Capture. United States: N. p., 2016. Web. doi:10.1021/acs.jpcc.6b06810.
Shi, Wei, Siefert, Nicholas S., Baled, Hseen O., Steckel, Janice A., & Hopkinson, David P. Molecular Simulations of the Thermophysical Properties of Polyethylene Glycol Siloxane (PEGS) Solvent for Precombustion CO2 Capture. United States. doi:10.1021/acs.jpcc.6b06810.
Shi, Wei, Siefert, Nicholas S., Baled, Hseen O., Steckel, Janice A., and Hopkinson, David P. Thu . "Molecular Simulations of the Thermophysical Properties of Polyethylene Glycol Siloxane (PEGS) Solvent for Precombustion CO2 Capture". United States. doi:10.1021/acs.jpcc.6b06810. https://www.osti.gov/servlets/purl/1478188.
@article{osti_1478188,
title = {Molecular Simulations of the Thermophysical Properties of Polyethylene Glycol Siloxane (PEGS) Solvent for Precombustion CO2 Capture},
author = {Shi, Wei and Siefert, Nicholas S. and Baled, Hseen O. and Steckel, Janice A. and Hopkinson, David P.},
abstractNote = {Here, 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, which in turn leads to fewer hydrophobic pockets. The CO2/H2 solubility selectivity in PEGS is larger than that in PDMS due to a stronger interaction with CO2 in PEGS. Finally, it was found that CO2 absorption in PEGS could significantly improve the CO2–PEGS solution dynamics by 5–6 times, resulting in a decrease in solution viscosity and increase in diffusivity. These CO2 absorption effects are due to solution volume expansion upon CO2 absorption compared to the neat PEGS solvent volume and the possibility that CO2 acts as a “lubricant” to decrease the solvent–solvent interaction.},
doi = {10.1021/acs.jpcc.6b06810},
journal = {Journal of Physical Chemistry. C},
number = 36,
volume = 120,
place = {United States},
year = {2016},
month = {8}
}

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