Hydrophobic Polymeric Solvents for the Selective Absorption of CO₂ from Warm Gas Streams that also Contain H₂ and H₂O

Abstract

The hydrophobic polymers polydimethyl siloxane (PDMS) and polypropyleneglycol dimethylether (PPGDME) may provide an alternative to physical solvents based on the hydrophilic polymer polyethyleneglycol dimethylether (PEGDME) for the precombustion capture of CO2 from the warm, high pressure stream that also contains H2O and H2. PPGDME can be made with a linear repeat unit (PPGDMEl, poly(1,3-propanediol) dimethylether) or a branched repeat unit (PPGDMEb, poly(1,2-propanediol) dimethylether). The solubility of CO2 and H2 in each of the four solvents of specified average molecular weight (PEGDME 250, PDMS 550, PPGDMEl 678 and PPGDMEb 430) is determined between 25 and 120 °C at pressures to 10 MPa. CO2 is much more soluble in each solvent than H2; however, the solubility of CO2 decreases as the solubility of H2 increases with increasing temperature. PPGDMEl 678 and PPGDMEb 430 are comparable CO2 solvents. PPGDMEl 678 absorbs less H2 than all the other solvents, while PPGDMEb 430 absorbs significantly more H2. PDMS 550 is a very good CO2 solvent, absorbing more CO2 than all of the other solvents at all temperatures except for PEGDME 250 at 25 °C. PDMS 550 absorbs more H2 than all of the other solvents.

Molecular Simulations of CO2, H2, H2O, and H2S Gas Absorption into Hydrophobic Poly(dimethylsiloxane) (PDMS) Solvent: Solubility and Surface Tension

“…Due to rich H 2 O concentration in the hot or warm high-pressure gas stream corresponding to CO 2 precombustion capture, hydrophobic solvents are preferred for selective CO 2 absorption over H 2 and H 2 O. 3 CO 2 and H 2 absorption in hydrophobic poly-(dimethylsiloxane) (PDMS) solvents (2−50 repeating [−Si-(CH 3 ) 2 O−] monomers) have been experimentally investigated. 3 There are several advantages for this type of polymerlike solvent, including hydrophobicity, low volatility, low viscosity, thermal stability, and commercial availability.…”

“…3 CO 2 and H 2 absorption in hydrophobic poly-(dimethylsiloxane) (PDMS) solvents (2−50 repeating [−Si-(CH 3 ) 2 O−] monomers) have been experimentally investigated. 3 There are several advantages for this type of polymerlike solvent, including hydrophobicity, low volatility, low viscosity, thermal stability, and commercial availability. CO 2 was found to be much more soluble than H 2 in this type of solvent.…”

Computer-aided molecular design in the continuous-molecular targeting framework using group-contribution PC-SAFT

“…In the second case study, we implement the proposed method for designing a solvent for the capture of CO 2 by physical absorption (Enick et al, 2013;Gwinner et al, 2006;Miller et al, 2010;Stavrou et al, 2014). The process topology includes the main absorption, desorption, and CO 2 compression steps of a pre-combustion CO 2 capture application by an IGCC power plant as described in Stavrou et al (2014) (Fig.…”

“…The molecular parameter space y is constrained by a convex hull, as detailed in Section 2.1. As a result of the limited set of groups considered here, molecules with more than one polar group or multiple rings are omitted, although they are known to outperform the considered structures (Enick et al, 2013;Gwinner et al, 2006;Stavrou et al, 2014). An extension of the GC-method for such groups can directly be integrated into the presented framework.…”

Thermally Stable Silicone Solvents for the Selective Absorption of CO2 from Warm Gas Streams That Also Contain H2 and H2O

“…10 PPGDME is much more hydrophobic than PEGDME, 10 and it is available in two forms: one based on a corn-derived linear monomer (PPGDME l ; poly(1,3-propanediol) dimethyl ether) and the other is based on the branched petroleum-derived methylated monomer (PPGDME b ; poly(1,2-propane diol)-dimethyl ether). Trimethylsilyl-terminated PDMS is an extremely hydrophobic solvent that is commercially available over an incredibly wide range of molecular weight.…”