Membranes having improved selectivity and recovery, and process for making same
AssigneeThe Dow Chemical Company
InventorsJohn A. Jensvold, Srikanth R. Chary, Wendy S. Jacks, Hans R. Keller, Theodore L. Parker, Damoder Reddy
Life of this patent
Estimating the term…
Abstract
The invention is a process for obtaining membranes having improved selectivity and recovery using a combination of heat treating and UV irradiation.
Claims16
A process for treating a gas separation membrane to improve its selectivity, comprising:
- A. first heating a membrane comprising a polymer having a UV excitable site and a labile protonic site in the polymeric backbone, such that a covalent bond is formed between said sites, at a temperature between about 60.degree. and 300.degree. C. for a time sufficient to relax excess free volume in the polymer;
- and
- B. the irradiating the membrane with a UV radiation source in the presence of oxygen for a time sufficient to surface oxidize the membrane to obtain treated membrane;
- wherein the treated membrane exhibits at least a 10 percent increase in selectivity with less than a 60 percent decrease in permeability compared to the untreated membrane and
- wherein the membrane comprises an unsubstituted or substituted polycarbonate, polyestercarbonate, polyester, polystyrene, polysulfone, polyethersulfone, polyether, polyarylester, polyethylene terepththalate, cellulose ester, polybenzazole, polyurethane, or copolymer or physical blend thereof.
A gas separation membrane comprising a thin discriminating layer comprising a polymer selected from the group consisting of an unsubstituted or substituted polycarbonate, polyestercarbonate, polyester, polystyrene, polysulfone, polyethersulfone, polyether, polyarylester, polyethylene teraphthalate, polybenzazole, polyurethane, or copolymer or physical blend thereof, which exhibits at least a 10 percent increase in selectivity with less than a 60 percent decrease in permeability after exposure to heat and UV irradiation to form a treated membrane compared to an untreated membrane.
Dependencies are inferred from the claim text.