I&EC 61 |
| Room temperature ionic liquids (RTILs) possess many desirable properties for CO2 separation and capture. The versatile chemistry of imidazolium-based RTILs allows for the design of tailored polymers, which may be implemented as solid, poly(RTIL) gas separation membranes. Poly(RTIL) monomers can be configured in a number ways. Novel single and "gemini" (tethered cations) type systems have been studied for their performance relating to CO2 separations involving H2, N2 and CH4. The substituents on the cation play an important role in determining the permeability and selectivity of the polymer films. For example, a polymer from a single cation monomer with a methyl group substituent exhibits CO2 permeability of ~7 Barrers with CO2/N2 = 31 and CO2/CH4 = 40. An analogous polymer with a hexyl group substituent shows CO2 permeability of 28 Barrers with CO2/N2 = 28 and CO2/CH4 = 16. CO2 flux can be improved by tailoring the cation with little sacrifice to CO2/N2 selectivity. On the other hand, "gemini" systems exhibit almost barrier-like behavior to light gases, with permeabilities of N2 and CH4 << 1 Barrer, but with lower separation factors for CO2/N2 and CO2/CH4 than observed in single cation polymers. The inclusion of polar subsituents such as oligo(ethylene glycol) units on the imidazolium cation serves to enhance separation selectivity with similar CO2 permeability. Synthetic methods, characterization and structure-property relationships for gas separations in these novel polymers will be discussed. |
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IEC Poster Session
8:00 PM-10:00 PM, Tuesday, August 21, 2007 BCEC -- Exhibit Hall - B2, Poster
Sci-Mix
Division of Industrial & Engineering Chemistry |