*5.2.3 Poly(ether-*b*-amide) rubbery copolymers (Pebax®)*

Pebax®—product of Arkema, is a group of thermoplastic elastomers, containing polyamide "hard" segment (e.g., nylon-6, nylon-12), and polyether "soft" segment (e.g., poly (ethylene oxide) [PEO], poly (tetramethylene oxide) [PTMEO]), which maintain the highly desirable combination of the toughness traditionally associated with polyamides and the flexibility/elasticity with polyether. Various Pebax® copolymers with different polyether/polyamide ratios were designed and synthesized to meet the requirements for different applications. Typical grades of commercial Pebax® 2533, 3533, 4011, 4033, 5533, 6633, 1074 and 1657 have been widely studied in literature for gas separation applications. For example, Pebax® 1657 containing 60 wt% polyether segment is a promising material showing good performance in CO2 separation from CH4 or N2 [117]. MTR has also demonstrated favorable economics for a hybrid separation process that utilized Pebax® 4011 in conjunction with an amine absorption polishing step for sour gas separation [118]. However, fewer reported C3+ hydrocarbon separation and removal from natural gas. Harrigan et al*.* [93] recently investigated the sour gas separation performance of five different grades of commercial Pebax® 2533, 5513, 3000, 1074 and 1657 under high pressure 6-component gas mixtures containing C2+ hydrocarbons.
