Gas Separation Membranes Based on Fluorinated and Perfluorinated Polymers

Abstract

A process for separating components of a gas mixture using gas-separation copolymer membranes. These membranes use a selective layer made from copolymers of an amorphous perfluorinated dioxolane and a fluorovinyl monomer. The resulting membranes have superior selectivity performance for gas pairs of interest while maintaining fast gas permeance compared to membranes prepared using conventional perfluoropolymers, such as Teflon® AF, Hyflon® AD, and Cytop®.

We claim: 
     
         1 . A process for separating two components, A and B, of a gas mixture having a ratio (Rf) of A:B, comprising:
 (a) passing the gas mixture across a separation membrane having a feed side and a permeate side, the separation membrane having a selective layer comprising a copolymer comprising a perfluorinated dioxolane monomer selected from the group consisting of:   
       
         
           
           
               
               
           
         
         
           
           
               
               
           
         
       
       and tetrafluoroethylene (TFE);
 (b) providing a driving force for transmembrane permeation; 
 (c) withdrawing from the permeate side a permeate stream having a ratio (Rp) of A:B, where Rp>Rf; and 
 (d) withdrawing from the feed side a residue stream having a ratio (Rr) of A:B, where Rr<Rf. 
 
     
     
         2 . The process of  claim 1 , wherein the gas mixture comprises at least one gas selected from the group consisting of helium, hydrogen, oxygen, nitrogen, methane, and carbon dioxide. 
     
     
         3 . The process of  claim 1 , wherein component A is hydrogen. 
     
     
         4 . The process of  claim 1 , wherein component A is carbon dioxide. 
     
     
         5 . The process of  claim 1 , wherein component A is nitrogen. 
     
     
         6 . The process of  claim 1 , wherein component A is helium. 
     
     
         7 . The process of  claim 1 , wherein component B is methane. 
     
     
         8 . The process of  claim 1 , wherein the gas mixture further comprises methane and C 3+  hydrocarbon vapors. 
     
     
         9 . The process of  claim 1 , wherein component A is nitrogen and component B is methane. 
     
     
         10 . The process of  claim 1 , wherein component A is carbon dioxide and component B is methane. 
     
     
         11 . The process of  claim 1 , wherein component A is hydrogen and component B is methane. 
     
     
         12 . The process of  claim 1 , wherein component A is helium and component B is methane. 
     
     
         13 . The process of  claim 1 , wherein the separation membrane has a selective layer of thickness less than 10 μm.