The CO₂ permeability and mixed gas CO₂/H₂ selectivity of membranes composed of CO₂-philic polymers

Journal Article · Fri Apr 01 04:00:00 EDT 2011 · Journal of Membrane Science

DOI:https://doi.org/10.1016/j.memsci.2011.01.028· OSTI ID:1015213

Barillas, Mary Katharine ^[1]; Enick, Robert M. ^[1]; O’Brien, Michael ^[2]; Perry, Robert ^[2]; Luebke, David R. ^[3]; Morreale, Bryan D. ^[3]

---

1. National Energy Technology Lab. (NETL), Pittsburgh, PA, (United States); Univ. of Pittsburgh, PA (United States) Dept. of Chemical and Petrolium Engineering.
2. GE Global Research 1 Research Circle. Niskayuna, NY (United States)
3. National Energy Technology Lab. (NETL), Pittsburgh, PA, (United States)

The objective of this work was to design polymeric membranes that have very high CO₂ permeability and high mixed gas selectivity toward CO₂ rather than hydrogen. Therefore the membranes were based on "CO₂-philic" polymers that exhibit thermodynamically favorable Lewis acid:Lewis base and hydrogen bonding interactions with CO₂. CO₂-philic polymers that are solid at ambient temperature include polyfluoroacrylate (PFA); polyvinyl acetate (PVAc); and amorphous polylactic acid (PLA). Literature CO₂ permeability values for PVAc and PLA are disappointingly low. The cast PFA membranes from this study had low permeabilities (45 barrers at 25º C) and very low CO₂/H₂ selectivity of 1.4. CO₂-philic polymers that are liquid at ambient conditions include polyethylene glycol (PEG), polypropylene glycol (PPG), polybutylene glycol with a linear -((CH₂)₄O)-repeat unit (i.e., polytetramethylene ether glycol (PTMEG)), polybutylene glycol (PBG) with a branched repeat unit, perfluoropolyether (PFPE), poly(dimethyl siloxane) (PDMS), and polyacetoxy oxetane (PAO). A small compound, glycerol triacetate (GTA) was also considered because it is similar in chemical structure to a trimer of PVAc. These liquids were tested as supported liquid membranes (SLM) and also (with the exception of PAD and GTA) as rubbery, crosslinked materials. Mixed gas permeability was measured using equimolar mixtures of CO₂ and H₂ feed streams at one atmosphere total pressure in steady-state flux experiments over the 298-423 K temperature range. The most promising SLMs were those composed of PEG, PTMEG, GTA, and PDMS. For example, at 37º C the PEG-, PTMEG-, GTA- and PDMS-based SLMs exhibited CO₂/H₂ selectivity values of ~11, 9, 9, and 3.5, respectively, and CO₂ permeability values of ~800, 900, 1900, and 2000 barrers, respectively. Crosslinked versions of the PEG, PTMEG and PDMS membranes at 37º C exhibited selectivity values of ~5, 6, and 3.5, respectively, and CO₂ permeability values of ~50, 300, and 3000 barrers, respectively.

• Research Organization: National Energy Technology Laboratory (NETL), Pittsburgh, PA, Morgantown, WV, and Albany, OR (United States)
• Sponsoring Organization: USDOE Assistant Secretary for Fossil Energy (FE)
• OSTI ID: 1015213
• Report Number(s): NETL-TPR--2805
• Journal Information: Journal of Membrane Science, Journal Name: Journal of Membrane Science Journal Issue: 1-2 Vol. 372; ISSN 0376-7388
• Publisher: Elsevier
• Country of Publication: United States
• Language: English

Related Subjects

08 HYDROGEN
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
CARBON DIOXIDE CAPTURE
GAS SEPARATION MEMBRANES
HYDROGEN
LIQUID MEMBRANE
POLYETHERS
POLYMER