Patent ID: 7250545

Claim:
A membrane separation process for separating an olefin from a mixture of olefins and paraffins comprising: (a) providing a two-sided, selectively permeable membrane comprising a polymer or copolymer having repeating units of formula (II) in which R 1 is a moiety of composition selected from the group consisting of formula (Q), formula (T), and formula (S), in which the moiety R 1 is of formula (Q) in about 16% of the repeating units, of formula (T) in about 64% of the repeating units, and of formula (S) in about 20% of the repeating units (b) contacting one side of the membrane with a feed mixture comprising an olefin compound and a paraffin compound having a number of carbon atoms at least as great as the olefin compound, (c) causing the feed mixture to selectively permeate through the membrane, thereby forming on the second side of the membrane an olefin-enriched permeate composition which has a concentration of the olefin compound greater than that of the feed mixture, (d) removing from the second side of the membrane the olefin-enriched permeate composition, and (e) withdrawing from the one side of the membrane an olefin-depleted composition.