Composite membrane for facilitated transport processes

A dimensionally stable, composite membrane of a microporous film in laminar contact with a continuous perfluoro ion exchange resin layer is provided. The composite membrane comprises a continuous perfluoro ion exchange polymer layer which has an original, as-prepared, length, width and thickness, the ion exchange polymer layer being in laminar attachment to a film of a microporous material, preferably porous, expanded polytetrafluoroethylene (EPTFE), the microporous film having essentially the same length and width as the as-prepared continuous perfluoro ion exchange layer. The perfluoro ion exchange layer is swollen with a hydrophilic liquid to an extent that the hydrophilic liquid exceeds 20% by weight of the swollen, continuous perfluoro ion exchange layer. The swollen ion exchange layer exhibits less than a 5% increase in either length or width from its original, as-prepared, state, but it exhibits a substantial increase in thickness over its original, as-prepared, state. The method of use of a dimensionally stable, expanded polytetrafluoroethylene (EPTFE) and perfluoro ion exchange resin composite membrane in a facilitated transport unit operation is also provided, the composite membrane comprising a continuous perfluoro ion exchange polymer layer in laminar attachment to a film of porous EPTFE, the perfluoro ion exchange layer being swollen with a hydrophilic liquid. The method is used in the facilitated transport separation of acid gas from a hydrocarbon stream.