Polymeric nanofibrous composite membranes for energy efficient ethanol dehydration

Abstract

Membranes are provided for energy efficient purification of alcohol by pervaporation. Such membranes include a nanofibrous scaffold in combination with a barrier layer. The membranes also include zeolites in the barrier layer. The membranes may, in embodiments, also include a substrate.

What is claimed is: 
     
         1 . An article comprising:
 a nanofibrous scaffold comprising fibers having a diameter of from about 1 nm to about 20,000 nm; and   a hydrophilic barrier layer on at least a portion of a surface of said nanofibrous scaffold, the hydrophilic barrier layer comprising a polymer,   wherein the nanofibrous scaffold, the hydrophilic barrier layer, or both, further comprise at least one zeolite.   
     
     
         2 . The article of  claim 1 , wherein the nanofibrous scaffold comprises a polymer selected from the group consisting of polyolefins, polysulfones, fluoropolymers, polyesters, polyamides, polycarbonates, polystyrenes, polynitriles, polyacrylates, polyacetates, polyalcohols, polysaccharides, proteins, polyalkylene oxides, polyurethanes, polyureas, polyimines, polyacrylic acids, polymethacrylic acids, polysiloxanes, poly(ester-co-glycol) copolymers, poly(ether-co-amide) copolymers, derivatives thereof and copolymers thereof. 
     
     
         3 . The article of  claim 1 , wherein the nanofibrous scaffold comprises a polymer selected from the group consisting of polyethylene, polypropylene, polyethersulfone, polyvinylidene fluoride, polyethylene terephthalate, polytrimethylene terephthalate, polybutylene terephthalate, nylon 6, nylon 66, nylon 12, polystyrene, polyacrylonitrile, polymethyl methacrylate, polyvinyl acetate, polyvinyl alcohol, chitosan, cellulose, collagen, gelatin, polyethylene oxide, polyethylene glycol, polyvinyl chloride, polyethylene imine, polyvinylpyrrolidone, polydimethylsiloxane, derivatives thereof and copolymers thereof. 
     
     
         4 . The article of  claim 1 , wherein the nanofibrous scaffold has a thickness of from about 1 μm to about 500 μm. 
     
     
         5 . The article of  claim 1 , wherein the polymer is a hydrophilic polymer selected from the group consisting of polysaccharides, polyalcohols, polyalkylene oxides, derivatives thereof and copolymers thereof, and wherein the hydrophilic barrier layer has a thickness from about 0.25 to about 20 μm. 
     
     
         6 . The article of  claim 1 , wherein the polymer is a hydrophilic polymer selected from the group consisting of chitosan, cellulose, crosslinked polyvinyl alcohol, crosslinked polyethylene oxide, derivatives thereof and copolymers thereof. 
     
     
         7 . The article of  claim 1 , wherein the zeolite is selected from the group consisting of type A, type X, type P, type Y, natural zeolites, and combinations thereof. 
     
     
         8 . The article of  claim 1 , wherein the zeolite has a zeolite has a mean micropore diameter from about 2.8 Angstroms to about 8 Angstroms. 
     
     
         9 . The article of  claim 1 , wherein the hydrophilic barrier layer includes the at least one zeolite, the at least one zeolite being present in the hydrophilic barrier layer in amounts from about 0.1% by weight to about 50% by weight of the hydrophilic barrier layer. 
     
     
         10 . The article of  claim 1 , further comprising an additional barrier layer between the nanofibrous scaffold and the hydrophilic barrier layer, the additional barrier layer formed from a material selected from the group consisting of cellulose nanofibers, chitin nanofibers, and combinations thereof, wherein the additional barrier layer has a thickness from about 0.25 μm to about 2.5 μm. 
     
     
         11 . The article of  claim 1 , further comprising a substrate, wherein the nanofibrous scaffold is applied to at least a portion of the substrate. 
     
     
         12 . The article of  claim 11 , wherein the substrate comprises a polymer selected from the group consisting of polyolefins, polyesters, polyamides, polyurethanes, polysulfones, polyureas, fluorinated polymers, derivatives thereof and copolymers thereof. 
     
     
         13 . The article of  claim 12 , wherein the polymer is selected from the group consisting of polyethylene, polypropylene, polyethylene terephthalate, polytrimethylene terephthalate, polybutylene terephthalate, nylon 6, nylon 66, nylon 12, derivatives thereof, and copolymers thereof, polyetherketones, polystyrene, sulfonated polyetherketones, sulfonated polystyrene, glass, cellulose, derivatives thereof, and copolymers thereof. 
     
     
         14 . The article of  claim 11 , wherein the substrate is selected from the group consisting of polysulfones, cellulose acetates, fluoropolymers, polyamides, polyimides, and combinations thereof, and wherein the substrate has a pore size of from about 5 nm to about 500 nm. 
     
     
         15 . A method for purifying an alcohol by pervaporation, the method comprising contacting the alcohol with the article of  claim 1 . 
     
     
         16 . An article comprising:
 a substrate;   a nanofibrous scaffold comprising fibers having a diameter of from about 1 nm to about 20,000 nm applied to a surface of the substrate; and   a hydrophilic barrier layer on said nanofibrous scaffold on a surface opposite a surface applied to said substrate comprising a polymer in combination with at least one zeolite, wherein the hydrophilic barrier layer has a thickness from about 0.25 μm to about 20 μm.   
     
     
         17 . The article of  claim 16 , wherein the substrate comprises a polymer selected from the group consisting of polyolefins, polyesters, polyamides, polyurethanes, polysulfones, polyureas, fluorinated polymers, derivatives thereof and copolymers thereof. 
     
     
         18 . The article of  claim 16 , wherein the nanofibrous scaffold comprises a polymer selected from the group consisting of polyolefins, polysulfones, fluoropolymers, polyesters, polyamides, polycarbonates, polystyrenes, polynitriles, polyacrylates, polyacetates, polyalcohols, polysaccharides, proteins, polyalkylene oxides, polyurethanes, polyureas, polyimines, polyacrylic acids, polymethacrylic acids, polysiloxanes, poly(ester-co-glycol) copolymers, poly(ether-co-amide) copolymers, derivatives thereof and copolymers thereof. 
     
     
         19 . The article of  claim 16 , wherein the nanofibrous scaffold has a thickness of from about 1 μm to about 500 μm and possesses voids with an effective diameter of from about 10 nm to about 200 μm. 
     
     
         20 . The article of  claim 16 , wherein the polymer is a hydrophilic polymer selected from the group consisting of polysaccharides, polyalcohols, polyalkylene oxides, derivatives thereof and copolymers thereof. 
     
     
         21 . The article of  claim 16 , wherein the zeolite is selected from the group consisting of type A, type X, type P, type Y, natural zeolites, and combinations thereof, having a mean micropore diameter from about 2.8 Angstroms to about 8 Angstroms. 
     
     
         22 . The article of  claim 16 , wherein zeolite is present in the hydrophilic barrier layer in amounts from about 0.1% by weight to about 50% by weight of the hydrophilic barrier layer. 
     
     
         23 . The article of  claim 16 , further comprising an additional barrier layer between the nanofibrous scaffold and the hydrophilic barrier layer, the additional barrier layer formed from a material selected from the group consisting of cellulose nanofibers, chitin nanofibers, and combinations thereof, wherein the additional barrier layer has a thickness from about 0.25 μm to about 2.5 μm. 
     
     
         24 . A method for purifying an alcohol by pervaporation, the method comprising contacting the alcohol with the article of  claim 16 .