A separation membrane structure comprises a porous support, and a separation membrane formed on the porous support. The separation membrane has an average pore diameter of greater than or equal to 0.32 nm and less than or equal to 0.44 nm. The separation membrane includes addition of at least one of a metal cation or a metal complex that tends to adsorb nitrogen in comparison to methane.

Membranes, methods of making the membranes, and methods of using the membranes are described herein. The membranes can comprise a gas permeable support layer, an inorganic layer disposed on the support, the inorganic layer comprising a plurality of discreet nanoparticles having an average particle size of less than 1 micron, and a selective polymer layer disposed on the inorganic layer, the selective polymer layer comprising a selective polymer having a CO.sub.2:N.sub.2 selectivity of at least 10 at 57 C. In some embodiments, the membrane can be selectively permeable to an acidic gas. The membranes can be used, for example, to separate gaseous mixtures, such as flue gas.

Provided is a gas separation membrane for purifying mixed raw material gas including condensable gas, said gas separation membrane exhibiting excellent separation ability and being capable of maintaining a gas permeation rate at a high level for a long time under a condensable gas atmosphere.

Membranes, methods of making the membranes, and methods of using the membranes are described herein. The membranes can comprise a gas permeable support layer, an inorganic layer disposed on the support, the inorganic layer comprising a plurality of discreet nanoparticles having an average particle size of less than 1 micron, and a selective polymer layer disposed on the inorganic layer, the selective polymer layer comprising a selective polymer having a CO.sub.2:N.sub.2 selectivity of at least 10 at 57 C. In some embodiments, the membrane can be selectively permeable to an acidic gas. The membranes can be used, for example, to separate gaseous mixtures, such as flue gas.

The invention provides mixed matrix membranes (MMMs) for olefin/paraffin separation and methodes of making and using the same. The MMMs comprise a continuous polymer matrix with metal doped zeolite nano-particles. A separation technology based upon the composite membranes is effective for propylene and other olefin separation from olefin/paraffin mixtures, and the separation is more energy-efficient than the conventional cryogenic technique.

The invention provides mixed matrix membranes (MMMs) for olefin/paraffin separation and methodes of making and using the same. The MMMs comprise a continuous polymer matrix with metal doped zeolite nano-particles. A separation technology based upon the composite membranes is effective for propylene and other olefin separation from olefin/paraffin mixtures, and the separation is more energy-efficient than the conventional cryogenic technique.

Provided is a gas separation membrane containing polysaccharides and being characterized by having a crystallinity of 17% or lower, the crystallinity being represented by equation (1) below: (1) Crystallinity (%)=[I.sub.c/(I.sub.c+I.sub.a)]?100 (In equation (1), I.sub.c is the sum of the integrals of the scattering intensities of crystalline peaks obtained from X-ray diffraction analysis of the gas separation membrane, and I.sub.a is the sum of the integrals of the scattering intensities of the amorphous halo).

The invention provides a high permeance and high selectivity facilitated transport membrane comprising a very small pore, nanoporous polyethersulfone (PES)/polyvinylpyrrolidone (PVP) blend support membrane, a hydrophilic polymer inside the very small nanopores on the skin layer surface of the support membrane, a thin, nonporous, hydrophilic polymer layer coated on the surface of the support membrane, and metal salts incorporated in the hydrophilic polymer layer coated on the surface of the support membrane and the hydrophilic polymer inside the very small nanopores, a method of making this membrane, and the use of this membrane for olefin/paraffin separations, particularly for propylene/propane and ethylene/ethane separations.

Metallopolyimide precursor fibers for aging-resistant carbon molecular sieve hollow fiber membranes having enhanced selectivity include transition metal cations complexed with electronegative regions of a polyimide. CMS membranes are made by pyrolyzing the metallopolyimide precursor fibers. The cations are introduced by including, in the bore fluid used to extrude the fibers, either a salt of the transition metal and an inorganic anion or a transition metal/organic ligand complex.

Metallopolyimide precursor fibers for aging-resistant carbon molecular sieve hollow fiber membranes having enhanced selectivity include transition metal cations complexed with electronegative regions of a polyimide. CMS membranes are made by pyrolyzing the metallopolyimide precursor fibers. The cations are introduced by including, in the spin dope composition used to extrude the fibers, either a salt of the transition metal and an inorganic anion or a transition metal/organic ligand complex.