A process for producing nitrogen-rich air by feeding high temperature air at 150 C. or more to an air separation membrane module is described. After being placed at 175 C. for two hours, the air separation module exhibits a shape-retention ratio of 95% or more in one embodiment. The nitrogen-rich air can be fed to a fuel tank for an aircraft, for example.

A process for separating a feed gas comprising polar and non-polar gases into a gas mixture enriched in polar gas(es) and a gas mixture depleted in polar gas(es), the process comprising passing the feed gas through a gas separation unit comprising at least two gas-separation modules in order of increasing selectivity for the polar gas(es), wherein the feed gas entering the gas separation unit comprises more than 35 mol % and up to 90 mol % of polar gas(es).

Described are composite hollow fibers filter membranes that include a porous polymeric hollow fiber support and a filter layer; methods of making the composite hollow fibers and using the composite hollow fibers as a filter membrane; methods of making a filter component or filter from the composite hollow fiber; and filter components and filters that contain the composite hollow fibers as filter membranes.

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.

The present invention provides nanofiltration membranes with reduced chemical reactivity that can be utilized in manufacturing processes where reactive feedstocks and/or products are utilized or produced. Methods of making and using the membranes are also provided.

In embodiments of the present disclosure, a CMS hollow fiber membranes may be prepared to have an ultrathin (e.g. 2 microns or less) separation layer. A precursor hollow fiber may be prepared as dual layer fibers having a thin sheath layer and a core layer. During pyrolysis, the sheath layer is transformed into an ultrathin separation layer. Porosity of the core layer substrate is well-maintained during pyrolysis, thereby enabling high permeance of the CMS hollow fiber membrane. Additionally, in some embodiments, the sheath layer of the precursor hollow fibers may be hybridized prior to pyrolysis. By hybridizing the sheath layer prior to pyrolysis, a CMS hollow fiber may having an improved separation factor, including for example increased carbon dioxide/methane selectivity, may be provided.

Provided is a method for producing a porous polyimide film with which it is possible to suppress the occurrence of curling in the polyimide-fine particle composite film obtained by firing the unfired composite film. The method for producing a porous polyimide film of the present invention includes, in the following order: forming an unfired composite film using a varnish that contains a resin including polyamide acid and/or polyimide, fine particles, and a solvent; immersing the unfired composite film in a solvent including water; firing the unfired composite film to obtain a polyimide-fine particle composite film; and removing the fine particles from the polyimide-fine particle composite film.

An ion-permeable membrane is substantially free of holes and has excellent ion permeability, heat resistance, strength, and flexibility. A battery electrolyte membrane uses the ion-permeable membrane, and can form an electrode composite body. The polymer-ion-permeable membrane has an average radius of free volume of 0.32-0.50 nm.

A carbon molecular sieve (CMS) membrane is made by pyrolyzing, to a peak pyrolysis temperature T.sub.P, a hollow fiber membrane having a polymeric sheath surrounding a polymeric core, anti-substructure collapse particles present in pores formed in the polymeric core help prevent collapse of pores formed in the hollow fiber membrane before pyrolysis. The anti-substructure collapse particles are made of a material or materials that either: i) have a glass transition temperature T.sub.G higher than T.sub.P, ii) have a melting point higher than T.sub.P, or ii) are completely thermally decomposed during said pyrolysis step at a temperature less than T.sub.P. The anti-substructure collapse particles are not soluble in a solvent used for dissolution of the polymeric material of the core.