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

TY - JOUR

T1 - The CO2 permeability and mixed gas CO2/H2 selectivity of membranes composed of CO2-philic polymers

AU - Barillas, Mary Katharine

AU - Enick, Robert M.

AU - O'Brien, Michael

AU - Perry, Robert

AU - Luebke, David R.

AU - Morreale, Bryan D.

PY - 2011/4/15

Y1 - 2011/4/15

N2 - 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 (45barrers at 25°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 PAO 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 298-423K temperature range. The most promising SLMs were those composed of PEG, PTMEG, GTA, and PDMS. For example, at 37°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 2000barrers, respectively. Crosslinked versions of the PEG, PTMEG and PDMS membranes at 37°C exhibited selectivity values of ∼5, 6, and 3.5, respectively, and CO2 permeability values of ∼50, 300, and 3000barrers, respectively.

AB - 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 (45barrers at 25°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 PAO 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 298-423K temperature range. The most promising SLMs were those composed of PEG, PTMEG, GTA, and PDMS. For example, at 37°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 2000barrers, respectively. Crosslinked versions of the PEG, PTMEG and PDMS membranes at 37°C exhibited selectivity values of ∼5, 6, and 3.5, respectively, and CO2 permeability values of ∼50, 300, and 3000barrers, respectively.

KW - Carbon dioxide capture

KW - Gas separation membranes

KW - Hydrogen

KW - Liquid membrane

KW - Polyethers

KW - Polymer

UR - https://www.scopus.com/pages/publications/79953024600

UR - https://www.scopus.com/pages/publications/79953024600#tab=citedBy

U2 - 10.1016/j.memsci.2011.01.028

DO - 10.1016/j.memsci.2011.01.028

M3 - Article

SN - 0376-7388

VL - 372

SP - 29

EP - 39

JO - Journal of Membrane Science

JF - Journal of Membrane Science

IS - 1-2

ER -