Abstract
A chemically specific coordination complex between solvated Ag + ions in polymer membranes and double-bonded olefin molecules, such as ethylene or propylene, results in a facilitated transport mechanism and increased olefin-paraffin selectivity. However, previous studies on Ag + -containing facilitated transport membranes report poor stability of the Ag + carrier, especially in the presence of reducing gases, such as H 2 , H 2 S, and acetylene commonly present in industrial process streams. Solid polymer electrolytes consisting of crosslinked poly(ethylene glycol) diacrylate and up to 70 wt% silver bis(trifluoromethylsulfonyl)imide (AgTf 2 N) salt are synthesized through a facile and scalable UV-crosslinking process. Following over 10 weeks of pure H 2 permeation at 4 bar and 35°C, the membrane retains 90% of its initial pure-gas ethylene-ethane selectivity. X-ray photoelectron spectroscopy shows no change in the oxidation state of the dissolved Ag + ions. At the highest AgTf 2 N concentration (70 wt%), pure-gas ethylene-ethane selectivity and permeability are 21 and 4.0 Barrer, respectively, yielding performance surpassing the polymeric gas separation membrane upper bound. High ethylene-ethane permeability selectivity results largely from increased solubility selectivity in the Ag + -containing membranes. Dual-mode ethylene sorption is observed and modeled using a chemical equilibrium model. Diffusion coefficients are calculated according to the solution-diffusion model. • Crosslinked poly(ethylene glycol)-AgTf 2 N membranes surpass C 2 H 4 /C 2 H 6 upper bound • C 2 H 4 /C 2 H 6 transport properties are stable after 10 weeks of hydrogen permeation • Rubbery membranes show dual-mode sorption of C 2 H 4 and high solubility selectivity • C 2 H 4 sorption is reversible, and permeability is stable over long-term permeation • Membranes are plasticized by C 2 H 4 , demonstrated by diffusivity trends with pressure
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