用于燃烧前CO <sub>2</sub>捕集的聚乙二醇硅氧烷（PEGS）溶剂的热物理性质的分子模拟,The Journal of Physical Chemistry C

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用于燃烧前CO ₂捕集的聚乙二醇硅氧烷（PEGS）溶剂的热物理性质的分子模拟
The Journal of Physical Chemistry C ( IF 3.3 ) Pub Date : 2016-09-06 00:00:00 , DOI: 10.1021/acs.jpcc.6b06810
Wei Shi _{1,

2,

3} , Nicholas S. Siefert ₁ , Hseen O. Baled ₁ , Janice A. Steckel ₁ , David P. Hopkinson ₁

Affiliation

通过分子模拟研究了PEGS中纯聚乙二醇硅氧烷溶剂（PEGS）的热物理性质以及COGS在298–373 K下的CO ₂，H ₂，H ₂ O和H ₂ S气体吸收。预测的PEGS溶剂中纯净PEGS密度，热容量，表面张力以及CO ₂和H ₂溶解度与实验数据吻合得很好，典型差异为0.8–20％，而预测的PEGS溶剂粘度为1.7–2.5倍大于实验数据。298 K下PEGS中的气体溶解度按以下顺序降低，即H ₂ O（31000）> H ₂ S（230）> CO ₂（33）> H ₂（1），其遵循与气体-PEGS相互作用相同的顺序。相反，在298 K下PEGS中的气体扩散率以相反的方式降低，即H ₂（1）> CO ₂（0.22）≈H ₂ S（0.12）> H ₂ O（0.018）。括号中的数字是相对于H ₂的对应值。与广泛研究的聚（二甲基硅氧烷）（PDMS）溶剂相比，PEGS具有更强的亲水性，因为它与H ₂ O的相互作用更强，支链-CH ₃基团更少，从而导致疏水口袋减少。由于与CO _2的相互作用更强，因此PEGS中的CO ₂ / H ₂溶解度选择性比PDMS中的高。在PEGS中。最后，发现PEGS中的CO ₂吸收可以显着改善CO ₂ -PEGS溶液动力学性能5-6倍，从而导致溶液粘度降低和扩散率增加。这些CO ₂吸收效果是由于与纯PEGS溶剂体积相比，CO ₂吸收后溶液体积膨胀，以及CO ₂充当“润滑剂”以减少溶剂与溶剂相互作用的可能性。

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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, 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.

更新日期：2016-09-06

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