Abstract
Membranes that are resistant to water vapor permeation have potential in natural gas sweetening by reducing the need for pretreatment. The perfluorinated polymer Teflon AF1600 has proven resistance to water vapor, which is adapted here in the form of composite membranes consisting of a Teflon AF1600 protective layer on membranes of the polyimide 4,4′-(hexafluoroisopropylidene) diphthalic anhydride 2,3,5,6-tetramethyl-1,4-phenylenediamine (6FDA-TMPDA) as well as Polymer of Intrinsic Micro-porosity (PIM-1). The permeability of CO2 and CH4 through the composite membranes was shown to be a function of the respective permeabilities of the individual polymer layers, with the Teflon AF1600 layer providing the majority of the resistance to mass transfer. Upon exposure to water, the composite membranes had reduced water permeation of 7–13% compared to pure membranes of 6FDA-TMPDA and PIM-1, because of the water resistance of the Teflon AF1600 layer. It was observed that water permeated as clusters through the composite structure. Under CO2-CH4 mixed gas conditions, 6FDA-TMPDA layer permselectivity performance was reduced and became comparable to Teflon AF1600, while the PIM-1 layer retained much of its high permselectivity performance. Importantly, at water activities below 0.2 the PIM-1 composite membrane achieved higher permeability for CO2 compared to water.
Highlights
Gas separation polymeric membranes that are resilient to water permeance have important application in the natural gas sweetening industry [1,2,3]
CH4 through the composite membranes was shown to be a function of the respective permeabilities of the individual polymer layers, with the Teflon AF1600 layer providing the majority of the resistance to mass transfer
The hydrophobicity of the composite membranes is demonstrated by water contact angles on the surface, provided in Table 2 along with that of pure Teflon AF1600 film
Summary
Gas separation polymeric membranes that are resilient to water permeance have important application in the natural gas sweetening industry [1,2,3]. Most natural gas sweetening processes involving membranes require extensive pretreatment to remove water vapor and protect the membrane, which is generally through a glycol dehydration process This creates a problem in that glycol vapor entrained in the natural gas will reduce the separation performance of downstream polymeric membranes [5]. For a single gas permeation measurement, there is no concentration polarization on either the feed or permeate sides, and the total resistance to flow is related to only to the respective thickness of the different layers and their respective permeabilities: RT = RL1 + RL2 =. Concentration polarization can be avoided on the feed and permeate sides of the membrane if operated at low stage cuts, and the resistance and permeability of the composite membrane can be determined from the performance of the individual layers of the composite structure.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
