Abstract: Disclosed is an asymmetric gas separation membrane made of a soluble aromatic polyimide having a specific repeating unit, the soluble aromatic polyimide including: as a tetracarboxylic acid component, a biphenyl structure and a phenyl structure; as a diamine component, a 3,3?-diaminodiphenyl sulphone and a diaminodibenzothiophene, a diaminodibenzothiophene=5,5-dioxide, a diaminothioxanthene-10,10-dione, or a diaminothioxanthene-9,10,10-trione. Disclosed is a method for selectively separating and recovering a specific gas species from a mixed gas composed of a plurality of gas species using the asymmetric gas separation membrane, a method for selectively separating and recovering a nitrogen-rich gas from air using the asymmetric gas separation membrane, and a method for selectively separating carbon dioxide gas from a mixed gas containing carbon dioxide and methane and recovering methane-rich gas using the asymmetric gas separation membrane.

Abstract: In a hollow fiber element constituting a separation membrane module for separating an organic vapor, at least one end part of a fiber bundle consisting of multiple hollow fiber membranes having a selective permeability is fixed and bound with a tube sheet formed by a cured material, in which an epoxy composition (A) has been cured by using a hardener (B). A glass transition temperature of said cured material is not less than 160° C., a minimum elongation at break thereof is not less than 7.0%, and an elution ratio thereof is less than 5%. For this reason, the hollow fiber element has enough endurance to retain a gas-tightness of an internal space of the hollow fiber membrane and an external space of the hollow fiber membrane even in use under organic vapor with an elevated temperature and high pressure.

Abstract: An asymmetric gas separation membrane made of an aromatic polyimide mainly containing repeating units having an ether bond which is heated at a temperature near a softening point (Ts) of the aromatic polyimide, and a method for separating methanol from a methanol-containing mixed organic vapor by allowing methanol to selectively permeate the asymmetric gas separation membrane using the membrane.

Abstract: The present invention relates to an asymmetric hollow fiber membrane for gas separation made of a soluble aromatic polyimide, wherein an orientation index is 1.3 or less, a separation coefficient ?(P?O2/P?N2) as a permeation rate ratio of oxygen gas/nitrogen gas at 40° C. is 5.3 or more, and a tensile fracture elongation is 15% or more.

Abstract: An asymmetric gas separation membrane made of an aromatic polyimide mainly containing repeating units having an ether bond which is heated at a temperature near a softening point (Ts) of the aromatic polyimide, and a method for separating methanol from a methanol-containing mixed organic vapor by allowing methanol to selectively permeate the asymmetric gas separation membrane using the membrane.

Abstract: An asymmetric hollow fiber gas separation membrane obtained by subjecting an asymmetric hollow fiber polyimide membrane to a heat treatment having a maximum temperature of from 350 to 450° C., wherein the asymmetric hollow fiber polyimide membrane is formed with a polyimide essentially having a repeating unit represented by a general formula (1); is excellent in a solvent resistance and a thermal stability, and as well has such a mechanical strength that a tensile elongation at break is not less than 10% as a hollow fiber membrane.

Abstract: There is disclosed an asymmetric gas separation membrane exhibiting both improved gas separation performance and improved mechanical properties, which is made of a soluble aromatic polyimide comprised of a repeating unit represented by general formula (1): wherein B in general formula (1) B comprises 10 to 70 mol % of tetravalent unit B1 represented by general formula (B1) and 90 to 30 mol % of tetravalent unit B2 represented by general formula (B2), and A in general formula (1) comprises 10 to 50 mol % of bivalent unit A1 represented by general formula (A1a) or the like and 90 to 30 mol % of bivalent unit A2 represented by general formula (A2a) or the like.

Abstract: Disclosed are a gas separation membrane and a gas separation method in which at least one species of organic vapor is separated and recovered from an organic vapor mixture using the gas separation membrane. The gas separation membrane is made of an aromatic polyimide composed of a tetracarboxylic acid component consisting of an aromatic ring-containing tetracarboxylic acid and a diamine component comprising 10 to 90 mol % of a combination of (B1) 3,4?-diaminodiphenyl ether and (B2) 4,4?-diaminodiphenyl ether at a B1 to B2 molar ratio, B1/B2, ranging from 10/1 to 1/10, and 10 to 90 mol % of other aromatic diamine.

Abstract: A hollow fiber element constituting a separation membrane module for separating an organic vapor is disclosed. At least one end part of a fiber bundle consisting of multiple hollow fiber membranes having a selective permeability is fixed and bound with a tube sheet formed by a cured material of an epoxy resin composition. Herein, a resin component of the epoxy resin composition contains an epoxy compound (A) represented by the following formula (1), an epoxy compound (B) represented by the following formula (2) and an aromatic amine compound (C), and wherein the epoxy compound (A) and the epoxy compound (B) are blended at a proportion in a range from 90:10 to 60:40 by weight; wherein R denotes alkyl group having 1 to 3 carbon atoms or hydrogen atom.

Abstract: The present invention relates to an asymmetric hollow fiber membrane for gas separation made of a soluble aromatic polyimide, wherein an orientation index is 1.3 or less, a separation coefficient ?(P?O2/P?N2) as a permeation rate ratio of oxygen gas/nitrogen gas at 40° C. is 5.3 or more, and a tensile fracture elongation is 15% or more.

Abstract: In a hollow fiber element constituting a separation membrane module for separating an organic vapor, at least one end part of a fiber bundle consisting of multiple hollow fiber membranes having a selective permeability is fixed and bound with a tube sheet formed by a cured material, in which an epoxy composition (A) has been cured by using a hardener (B). A glass transition temperature of said cured material is not less than 160° C., a minimum elongation at break thereof is not less than 7.0%, and an elution ratio thereof is less than 5%. For this reason, the hollow fiber element has enough endurance to retain a gas-tightness of an internal space of the hollow fiber membrane and an external space of the hollow fiber membrane even in use under organic vapor with an elevated temperature and high pressure.

Abstract: There is disclosed an asymmetric gas separation membrane exhibiting both improved gas separation performance and improved mechanical properties, which is made of a soluble aromatic polyimide comprised of a repeating unit represented by general formula (1): wherein B in general formula (1) B comprises 10 to 70 mol % of tetravalent unit B1 represented by general formula (B1) and 90 to 30 mol % of tetravalent unit B2 represented by general formula (B2), and A in general formula (1) comprises 10 to 50 mol % of bivalent unit A1 represented by general formula (A1a) or the like and 90 to 30 mol % of bivalent unit A2 represented by general formula (A2a) or the like.

Abstract: An asymmetric hollow fiber gas separation membrane obtained by subjecting an asymmetric hollow fiber polyimide membrane to a heat treatment having a maximum temperature of from 350 to 450° C., wherein the asymmetric hollow fiber polyimide membrane is formed with a polyimide essentially having a repeating unit represented by a general formula (1); is excellent in a solvent resistance and a thermal stability, and as well has such a mechanical strength that a tensile elongation at break is not less than 10% as a hollow fiber membrane.

Abstract: Disclosed are a gas separation membrane and a gas separation method in which at least one species of organic vapor is separated and recovered from an organic vapor mixture using the gas separation membrane. The gas separation membrane is made of an aromatic polyimide composed of a tetracarboxylic acid component consisting of an aromatic ring-containing tetracarboxylic acid and a diamine component comprising 10 to 90 mol % of a combination of (B1) 3,4?-diaminodiphenyl ether and (B2) 4,4?-diaminodiphenyl ether at a B1 to B2 molar ratio, B1/B2, ranging from 10/1 to 1/10, and 10 to 90 mol % of other aromatic diamine.

Abstract: A hollow fiber element constituting a separation membrane module for separating an organic vapor is disclosed. At least one end part of a fiber bundle consisting of multiple hollow fiber membranes having a selective permeability is fixed and bound with a tube sheet formed by a cured material of an epoxy resin composition. Herein, a resin component of the epoxy resin composition contains an epoxy compound (A) represented by the following formula (1), an epoxy compound (B) represented by the following formula (2) and an aromatic amine compound (C), and wherein the epoxy compound (A) and the epoxy compound (B) are blended at a proportion in a range from 90:10 to 60:40 by weight; wherein R denotes alkyl group having 1 to 3 carbon atoms or hydrogen atom.

Abstract: Disclosed are a proton type ? zeolite in which an acid site showing a desorption peak with a range of ±100° C. with a center of 330° C. exists in a spectrum measured by the ammonia temperature programmed desorption method (NH3-TPD), and an amount of a strong acid site showing a desorption peak of 500° C. or higher is controlled to 2.5 ?mol/g or less, a method for preparing the same, and a process for preparing a phenol compound by oxidizing a benzene compound with a peroxide in the presence of the proton type ? zeolite.

Abstract: Disclosed are a proton type &bgr; zeolite in which an acid site showing a desorption peak with a range of ±100° C. with a center of 330° C. exists in a spectrum measured by the ammonia temperature programmed desorption method (NH3-TPD), and an amount of a strong acid site showing a desorption peak of 500° C. or higher is controlled to 2.5 &mgr;mol/g or less, a method for preparing the same, and a process for preparing a phenol compound by oxidizing a benzene compound with a peroxide in the presence of the proton type &bgr; zeolite.

Abstract: A process for producing a zirconium oxide precursor comprising precipitating a zirconium oxide precursor from an alcoholic solution of a zirconium compound, and a process for producing zirconium oxide having infrared absorption peaks assigned to an S—O bond between 1010 cm−1 and 1025 cm−1 and between 1035 cm−1 and 1050 cm−1, which comprises heat treating the zirconium oxide precursor prepared by the above process. The zirconium oxide precursor and the zirconium oxide obtained in the process are effective as a catalyst for removing or decomposing nitrogen oxides.

Abstract: There are disclosed a process for producing a dihydric phenol which comprises oxidizing a monohydric phenol by a peroxide compound in the presence of a &bgr;-zeolite, a ketone and a phosphoric acid, and a process for producing a dihydric phenol which comprises oxidizing a monohydric phenol in the presence of a &bgr;-zeolite, a ketone and a phosphoric acid, by feeding a monohydric phenol, hydrogen peroxide, a ketone and a phosphoric acid into a reactor in which a &bgr;-zeolite is charged, to oxidize the monohydric phenol into a dihydric phenol, and delivering the resultant reaction mixture from the reactor.

Abstract: There are disclosed a process for producing a dihydric phenol which comprises oxidizing a monohydric phenol by a peroxide compound in the presence of a &bgr;-zeolite, a ketone and a phosphoric acid, and a process for producing a dihydric phenol which comprises oxidizing a monohydric phenol in the presence of a &bgr;-zeolite, a ketone and a phosphoric acid, by feeding a monohydric phenol, hydrogen peroxide, a ketone and a phosphoric acid into a reactor in which a &bgr;-zeolite is charged, to oxidize the monohydric phenol into a dihydric phenol, and delivering the resultant reaction mixture from the reactor.