Stable facilitated transport membranes for olefin/paraffin separations

A method of making a stable high performance facilitated transport membrane comprising an asymmetric integrally-skinned polymeric membrane wherein the method comprises:

• (a) preparing an asymmetric integrally-skinned polymeric membrane comprising a relatively porous, thin, dense skin layer and having a CO2 permeance of at least 200 GPU and a CO2 over CH4 selectivity between 1.1 and 10 at 50° C. under 50-1000 psig, 10% CO2/90% CH4 mixed gas feed pressure;
• (b) preparing a hydrophilic polymer-nipped asymmetric integrally-skinned polymeric membrane by dripping an aqueous solution of a hydrophilic polymer with a concentration in a range of 50 ppm to 5000 ppm onto the surface of said asymmetric integrally-skinned polymeric membrane comprising a relatively porous, thin, dense skin layer prepared in step (a);
• and
• (c) preparing the facilitated transport membrane by soaking the relatively porous, thin, dense skin layer of said hydrophilic polymer-nipped asymmetric integrally-skinned polymeric membrane prepared in step (b) in an aqueous solution of a metal salt, or in an aqueous solution of a metal salt and hydrogen peroxide for a sufficient time to form the facilitated transport membrane wherein the relatively porous, thin, dense skin layer of the membrane comprises a metal salt, or a mixture of a metal salt and hydrogen peroxide.

A process for the separation of paraffins and olefins, using a stable high performance facilitated transport membrane comprising an asymmetric integrally-skinned polymeric membrane wherein the pores on the relatively porous, thin, dense skin layer of the membrane comprises a hydrophilic polymer, a metal salt, or a mixture of a metal salt and hydrogen peroxide, the process comprising:

• (a) providing a stable high performance facilitated transport membrane comprising an asymmetric integrally-skinned polymeric membrane wherein the pores on the relatively porous, thin, dense skin layer of the membrane comprises a hydrophilic polymer, a metal salt, or a mixture of a metal salt and hydrogen peroxide wherein said membrane is permeable to said olefin;
• (b) contacting a humidified olefin/paraffin mixture feed on one side of said stable high performance facilitated transport membrane to cause said olefin to permeate the membrane;
• and
• (c) removing from the opposite side of said membrane a permeate gas composition comprising at least a portion of said olefin which permeated through said membrane.