Multilayer aromatic polyamide thin-film composite membranes for separation of gas mixtures

A method of making a hollow fiber membrane for gas separation, the method comprising:

• dissolving a glassy polymer in a solvent to yield a solution, wherein the glassy polymer has a glass transition temperature greater than 50° C.;
• contacting the solution comprising the glassy polymer with an aromatic polyamide layer of a thickness between 20 nm and 200 μm, wherein the aromatic polyamide layer is formed by interfacial polymerization over a porous support of a thickness of between 30 μm and 100 μm layer;
• and
• drying the solution to form a coating of the glassy polymer on the aromatic polyamide layer, wherein the coating has a thickness less than 1 μm, and wherein the hollow fiber membrane has selectivity of helium over carbon dioxide of greater than 40.

A gas separation method comprising:

• contacting a gas feed stream comprising carbon dioxide and at least one of helium and hydrogen with a gas separation membrane comprising a hollow fiber membrane to yield a permeate stream and a reject stream, wherein a concentration of helium or hydrogen in the permeate stream exceeds the concentration of helium or hydrogen, respectively, in the gas feed stream, wherein the gas separation membrane has a selectivity of helium over carbon dioxide greater than 40, and wherein the gas separation membrane comprises:
• a porous support layer;
• an aromatic polyamide layer with a thickness between 20 nm and 200 μm formed on the porous support layer via interfacial polymerization, wherein the porous support layer has a thickness of between 30 μm and 100 μm;
• and
• a coating comprising a glassy polymer formed on the aromatic polyamide layer wherein the coating is less than 1 μm in thickness, wherein a glass transition temperature of the glassy polymer is greater than 50° C.