A high-performance hydroxyl-functionalized polymer of intrinsic microporosity for an environmentally attractive membrane-based approach to decontamination of sour natural gas. Issue 45 (14th October 2015)

• Record Type: Journal Article
• Authors: Yi, Shouliang; Ma, Xiaohua; Pinnau, Ingo; Koros, William J.
• Is Part Of: Journal of materials chemistry. Volume 3:Issue 45(2015)
• Page Start: 22794
• Page End: 22806
• Publication Date: 2015-10-14
• Subjects: Materials -- Research -- Periodicals; Chemistry, Analytic -- Periodicals; Environmental sciences -- Research -- Periodicals; 543.0284
• DOI: 10.1039/c5ta05928c
• Languages: English
• ISSNs: 2050-7488

Abstract

Abstract : Sorption and permeation properties of a hydroxyl-functionalized polymer with intrinsic microporosity are reported for aggressive sour natural gas separations. Abstract : Acid gases carbon dioxide (CO2 ) and hydrogen sulfide (H2 S) are important and highly undesirable contaminants in natural gas, and membrane-based removal of these contaminants is environmentally attractive. Although removal of CO2 from natural gas using membranes is well established in industry, there is limited research on H2 S removal, mainly due to its toxic nature. In actual field operations, wellhead pressures can exceed 50 bar with H2 S concentrations up to 20%. Membrane plasticization and competitive mixed-gas sorption, which can both lead to a loss of separation efficiency, are likely to occur under these aggressive feed conditions, and this is almost always accompanied by a significant decrease in membrane selectivity. In this paper, permeation and separation properties of a hydroxyl-functionalized polymer with intrinsic microporosity (PIM-6FDA-OH) are reported for mixed-gas feeds containing CO2, H2 S or the combined pair with CH4 . The pure-gas permeation results show no H2 S-induced plasticization of the PIM-6FDA-OH film in a pure H2 S feed at 35 °C up to 4.5 bar, and revealed only a slight plasticization up to 8 bar of pure H2 S. The hydroxyl-functionalized PIM membrane exhibited a significant pure-gas CO2 plasticization resistance up to 28 bar feed pressure. Mixed-gas (15% H2 S/15% CO2 /70% CH4 ) permeation results showed that the hydroxyl-functionalized PIM membrane maintained excellent separation performance even under exceedingly challenging feed conditions. The CO2 and H2 S permeability isotherms indicated minimal CO2 -induced plasticization; however, H2 S-induced plasticization effects were evident at the highest mixed gas feed pressure of 48 bar. Under this extremely aggressive mixed gas feed, the binary CO2 /CH4 and H2 S/CH4 permselectivities, and the combined CO2 and H2 S acid gas selectivity were 25, 30 and 55, respectively. Our results indicate that OH-functionalized PIM materials are very promising candidate membrane materials for simultaneous removal of CO2 and H2 S from aggressive natural gas feeds, which makes membrane-based gas separation technology an attractive option for clean energy production and reducing greenhouse gas emissions.