Ube Industries, Inc.

Hiroshi Makino

Yoshihiro Kusuki

Takashi Harada

Hiroshi Shimazaki

Tosio Isida

Hiroshi Yoshida

Kanji Nakagawa

Masayuki Nakatani

Asumaru Nakamura

A water vapor-containing gas is separated to a fraction thereof having an increased content of water vapor and a remaining fraction thereof having a decreased content of water vapor by a gas separating device which has at least one gas separating membrane having gas feed and delivery surfaces and a ratio P.sub.H.sbsb.2.sub.O /P.sub.CH.sbsb.4 of water vapor-permeating rate P.sub.H.sbsb.2.sub.O to methane gas permeating rate P.sub.CH.sbsb.4 of 200 or more, and preferably, made by an aromatic imide polymer, in such a manner that (1) a water vapor-containing feed gas is fed to a feed side of the gas separating device; (2) the feed gas is flowed along the gas feed surface of the gas separating membrane to allow a fraction of the feed gas to permeate through the gas separating membrane; (3) a drying gas containing 300 ppm or less of water vapor is fed to a delivery side of the gas separating device; (4) the fed drying gas is flowed along the delivery surface of the gas separating membrane to promote the permeation of water vapor through the gas separating membrane; (5) the permeated gas fraction is collected together with the flowed drying gas at the delivery side of the gas separating device; and (6) a remaining gas fraction not permeated through the gas separating membrane and having a decreased content of water vapor is recovered from the feed side of the gas separating device.

Method for removing water vapor from water vapor-containing gas

A gas separating material having excellent CO.sub.2 gas permeating property, mechanical property, and heat resistance has a gas separating layer comprising an aromatic imide polymer which contains 20 to 100 molar % of recurring units of the formula (I): ##STR1## wherein A.sub.1 is a tetravalent aromatic radical, A is a divalent aromatic radical of the formula (II): ##STR2## in which R and R.sup.1 are H or an organic radical, for example, --CH.sub.3, --C.sub.2 H.sub.5, --C.sub.3 H.sub.7, or --CH.sub.2 OH, and n is 0, 1, or 2.

Gas separating material

An aromatic polyimide composite membrane having a satisfactory gas-permeating property and an excellent gas-separating property comprises an aromatic polyimide porous membrane substrate and at least one coating layer which has been prepared (A) by coating at least one surface of the substrate with a dilute dope solution containing 0.01 to 5 parts by weight of a soluble aromatic polyimide and/or polyamic acid dissolved in a solvent which consists essentially of 100 parts by weight of a base component incapable of dissolving therein the substrate in an amount of 3% by weight or more and 0 to 15 parts by weight of an additional component capable of dissolving therein the 5% by weight or more of the aromatic polymeric material and compatible with the base component; and (B) by gradually evaporating the solvent from the coated dilute dope solution layer.

Aromatic polyimide composite separating membrane

A porous aromatic imide polymer membrane usable as a gas or liquid separator or concentrator is prepared by a process comprising the steps of:

Porous aromatic imide polymer membrane and a process for its manufacture

A modified polymeric membrane having an excellent separating property is produced by applying, to a porous polymeric membrane, a volatile treating liquid containing a modifying agent which consists of at least one member selected from: (A) volatile dissolving organic liquids each capable of dissolving therein at least 1% by weight of the porous polymeric membrane at a temperature of 25.degree. C.; and

Process for modifying porous polymeric membrane

An aromatic polyimide separating membrane is produced by a process comprising the steps of:

Production of aromatic polyimide separating membranes

An aromatic polyimide membrane having an excellent gas-separating property comprises (A) a substrate consisting of a porous membrane comprising at least one aromatic polyimide having at least 80 molar % of at least one type of recurring unit of the formula (I): ##STR1## wherein R is a tetravalent aromatic radical and R.sup.1 is a divalent aromatic radical, the porous membrane exhibiting a hydrogen gas permeability (PH.sub.2) of 1.times.10.sup.-5 to 5.times.10.sup.-1 cm.sup.3 /cm.sup.2.sec.cmHg and a ratio of hydrogen gas permeability (PH.sub.2) to carbon monoxide gas permeability (PCO) of 2 to 5; and (B) 50% or more, based on the weight of the porous membrane substrate, of a gas-separating liquid contained in the porous membrane substrate, the gas-separating liquid being substantially incapable of dissolving therein the porous membrane substrate and having a boiling point of 180.degree. C. or more.

Aromatic polyimide gas-separating membrane

A porous membrane of an aromatic polyimide having an enhanced permeability of a gas or liquid is produced by a process comprising the steps of

Process for producing porous aromatic polyimide membranes

Aromatic polyimide hollow fibers having an enhanced mechanical strength are produced by a process comprising the steps of: preparing a spinning dope solution of at least one aromatic polyimide having 90 molar % or more of a recurring unit of the formula (I). ##STR1## wherein R is a divalent aromatic radical, in a phenolic solvent; converting the dope solution into at least one filamentary stream thereof; and introducing the filamentary dope solution stream into a coagulating liquid having a coagulating rate coefficient of 1.5 microns/sec for the dope solution, to provide rigid hollow filaments.

Process for producing aromatic polyimide hollow filaments

An aromatic polyimide composite membrane having an excellent gas-separating property is produced by a process comprising the steps of: coating at least one surface of a substrate consisting of an aromatic polyimide porous membrane with a solution of 0.05% to 10% by weight of an aromatic polyamic acid in a polar organic solvent, which is not capable of dissolving the polyimide porous membrane, at a temperature not exceeding 140.degree. C.; after a during drying the resultant thin coating layer of the polyamic acid solution, heating the resultant polyamic acid layer at a temperature of 150.degree. C. or more so as to convert the polyamic acid layer to the corresponding polyimide layer.

Process for producing aromatic polyimide composite separating membrane

A gas separating material having excellent heat and chemical resistance, mechanical strength and gas-separating function, comprises a gas separating layer consisting of at least one dense film having a thickness of from 0.1 to 20 microns and comprising at least one aromatic imide polymer which comprises at least 80 molar % of at least one type of recurring unit of the formula (I): ##STR1## wherein R represents a divalent aromatic radical.

A polyimide semipermeable membrane is prepared by the process comprising the steps of:

Process for preparing aromatic polyimide semipermeable membranes

Aromatic polyimide fibers having an enhanced mechanical strength are produced by a process comprising the steps of: preparing a spinning dope solution of at least one aromatic polyimide having 90 molar % or more of a recurring unit of the formula (I): ##STR1## wherein R is a divalent aromatic radical, in a phenolic solvent; converting the dope solution into at least one filamentary stream thereof; solidifying the filamentary dope solution stream by removing the solvent therefrom to provide at least one undrawn filament, and; drawing the undrawn filament at a temperature of 20.degree. to 600.degree. C. at a draw ratio of 1.5 to 5.0.

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Ichihara, Japan

Hiroshi Makino