Mitsubishi Gas Chemical Company, Inc.

Mizushima Aroma Company, Ltd.

Toyobo Co., Ltd.

Toyo Boseki Kabushiki Kaisha

Fumiya Zaima

Masato Inari

Hideaki Fujita

Mutsuhiko Takeda

Isao Hagiwara

Fumio Ohkoshi

Masato Inary

Hiroshi Machida

Shuzabu Sakaguchi

Nobuo Namiki

Nirou Hoshishima

Yasumasa Norisue

Kazuo Tanaka

Hiroshi Ogawa

Takao Kawaki

Atsushi Okoshi

Masamichi Mizukami

Kinji Kato

Katsushige Hayashi

Yuh Miyauchi

Toshio Watanabe

Ko Kedo

Emiko Yokose

Tomohiro Sugawara

Masami Matsumoto

Kengi Nakaya

Hiroshi Watanabe

Kazutoshi Uozumi

Satoshi Ueno

In pretreating a pyridine ring-containing chelate resin which is used in the step for adsorption and collection of a heavy metal ion and a bromide ion derived from a catalyst from the oxidation reaction mother liquid in the process of producing a terephthalic acid, there may occur phenomena such as swelling of the resin, heat generation of the resin, and air bubbles generation, thereby causing fracture and deterioration of the resin. As a first treatment, Brconversion, under a certain condition, of a pyridine ring-containing chelate resin with an aqueous solution of hydrobromic acid is performed, and then as a second treatment, replacement with acetic acid solvent is performed, thereby making it possible to prevent fracture and deterioration of the resin.

Pretreatment method for chelate resin having pyridine ring used for collecting catalyst in terephthalic acid production process

Provided is a simple filtering operation method capable of conducting a filtering operation without clogging in a ceramic filter for a long period of time, in the operation of filtering fine crystals of an aromatic carboxylic acid in an oxidation reaction mother liquor obtained in a process of an aromatic carboxylic acid production by a cross-flow filtration using the ceramic filter. The present invention can be accomplished by conducting an operation for filtering the fine crystals and a back washing operation with a filtrate while maintaining a flowing circulation operation of the oxidation reaction mother liquor under predetermined conditions.

Crossflow type filtering operation method using ceramic filter

Provided is a simple filtering operation method capable of conducting a filtering operation without clogging in a ceramic filter for a long period of time, in the operation of filtering fine crystals of terephthalic acid in an oxidation reaction mother liquor obtained in a process of terephthalic acid production by a cross-flow filtration using the ceramic filter. The present invention can be accomplished by conducting an operation for filtering the fine crystals and a back washing operation with a filtrate while maintaining a flowing circulation operation of the oxidation reaction mother liquor under predetermined conditions.

A method of replacing a first dispersion medium, in a starting slurry composed of the first dispersion medium and either terephthalic acid crystals or isophthalic acid crystals, with a second dispersion medium, and apparatus therefore. The starting slurry is tangentially fed to a vertically extending cylindrical portion of a cyclone-shaped nozzle disposed at an upper portion of a replacement tank of a dispersion medium replacement apparatus, from a tangential direction of the cylindrical portion, and moves circularly along an inner wall of the cylindrical portion. The slurry circularly moving is then discharged from an opening which is disposed at a vertically lower end of the cylindrical portion and dispersed in a second dispersion medium which is fed from a lower portion of the replacement tank.

Method of replacing dispersion medium and apparatus therefor

In pretreating a pyridine ring-containing chelate resin which is used in the step for adsorption and collection of a heavy metal ion and a bromide ion derived from a catalyst from the oxidation reaction mother liquid in the process of producing an aromatic carboxylic acid, there may occur phenomena such as swelling of the resin, heat generation of the resin, and air bubbles generation, thereby causing fracture and deterioration of the resin. As a first treatment, Brconversion, under a certain condition, of a pyridine ring-containing chelate resin with an aqueous solution of hydrobromic acid is performed, and then as a second treatment, replacement with acetic acid solvent is performed, thereby making it possible to prevent fracture and deterioration of the resin.

Pretreatment method for chelate resin having pyridine ring used for collecting catalyst in aromatic carboxylic acid production process

A method of replacing a first dispersion medium in a starting slurry composed of the first dispersion medium and a terephthalic acid crystal with a second dispersion medium. The starting slurry is tangentially fed to a vertically extending cylindrical portion of a cyclone-shaped nozzle disposed at an upper portion of a replacement tank of a dispersion medium replacement apparatus, from a tangential direction of the cylindrical portion. The fed starting slurry moves circularly along an inner wall of the cylindrical portion. The slurry circularly moving is then discharged from an opening which is disposed at a vertically lower end of the cylindrical portion and dispersed in a second dispersion medium which is fed from a lower portion of the replacement tank. The replaced slurry composed of the terephthalic acid crystal and the second dispersion medium is mainly discharged from the lower portion of the replacement tank, and the first dispersion medium is mainly withdrawn from the upper portion of the replacement tank.

Method of replacing dispersion medium

A method of replacing a first dispersion medium in a starting slurry composed of the first dispersion medium and isophthalic acid crystals with a second dispersion medium. The starting slurry is tangentially fed to a vertically extending cylindrical portion of a cyclone-shaped nozzle disposed at an upper portion of a replacement tank of a dispersion medium replacement apparatus, from a tangential direction of the cylindrical portion. The fed starting slurry moves circularly along an inner wall of the cylindrical portion. The slurry circularly moving is then discharged from an opening which is disposed at a vertically lower end of the cylindrical portion and dispersed in a second dispersion medium which is fed from a lower portion of the replacement tank. The replaced slurry composed of isophthalic acid crystals and the second dispersion medium is mainly discharged from the lower portion of the replacement tank, and the first dispersion medium is mainly withdrawn from the upper portion of the replacement tank.

A method for producing isophthalic acid, comprising:

Process for production of isophthalic acid

A method for producing terephthalic acid comprising:

Process for production of terephthalic acid

The present invention relates to a multi-stage crystallization process which comprises the steps of feeding a solution of terephthalic acid or a slurry (raw slurry) containing terephthalic acid partially precipitated to a first crystallization vessel to precipitate the terephthalic acid therein; and feeding a slurry (crystallization slurry) containing the thus precipitated terephthalic acid sequentially to second and subsequent crystallization vessels, wherein while continuously supplying a cleaning solvent to a delivery conduit connecting the former-stage crystallization vessel and the next latter-stage crystallization vessel to each other, the crystallization slurry is fed through the delivery conduit. There is provided a multi-stage crystallization process using a solution of terephthalic acid or a slurry containing terephthalic acid partially precipitated as a raw material in which even when the process is operated for a period as long as several months, the delivery conduit is free from occurrence of clogging.

Method of crystallization

In the production of an alicyclic aldehyde, a starting aromatic aldehyde is converted into an aromatic acetal for protecting the formyl group. The aromatic ring of the aromatic acetal is then hydrogenated to convert the aromatic acetal into an alicyclic acetal, which is then hydrolyzed to cleave the acetal protecting group to obtain the aimed alicyclic aldehyde.

Process for producing alicyclic aldehydes

Disclosed are processes for industrially advantageously producing at a good yield respectively, a hydrogenated aromatic polycarboxylic acid and an acid anhydride thereof each having a high purity. The present invention provides processes for producing a hydrogenated aromatic polycarboxylic acid by (1) hydrogenating an aromatic polycarboxylic acid at a hydrogen partial pressure of 1 MPa or more by a batch system in the presence of a catalyst containing rhodium and palladium in a proportion of 0.5 to 10 parts by weight per 100 parts by weight of the aromatic polycarboxylic acid and by (2) feeding an aromatic polycarboxylic acid to a filling bed of a catalyst containing rhodium and palladium at a WHSV of 1 to 100 hto hydrogenate it at a hydrogen partial pressure of 1 MPa or more by a continuous flow system, and a process for producing a hydrogenated aromatic polycarboxylic anhydride by subjecting the hydrogenated aromatic polycarboxylic acid obtained by the processes described above to dehydration reaction with acetic anhydride of 0.64 to 5.7 times mole based on a carboxyl group of the hydrogenated aromatic polycarboxylic acid.

Process for producing hydrogenated aromatic polycarboxylic acid and process for producing hydrogenated aromatic polycarboxylic anhydride

Process for producing a hydrogenation product of an aromatic carboxylic acid

Dialkylnaphthalene is oxidized to naphthalenedicarboxylic acid in a lower aliphatic carboxylic acid solvent in the presence of a catalyst comprising a cobalt compound, a manganese compound and a bromine compound having an atomic ratio of manganese to cobalt of 0.03 to 0.5. The catalyst is supplied to the oxidation reaction zone so that the total amount of cobalt and manganese is 0.025 to 0.1 gram atom based on 1 gram mol of the dialkylnaphthalene. An oxidation product slurry is subjected to solid-liquid separation when the concentration of the naphthalenedicarboxylic acid in the slurry is 8 to 30% by weight. The process prevents the by-production of benzotricarboxylic acid such as trimellitic acid, thereby drastically reducing the incorporation of heavy metal complexes with trimellitic acid into naphthalenedicarboxylic acid crystals. The process optionally includes the addition of a polymer flocculant, this forming crystal aggregates with a large particle size and facilitating the separation of the crystals from the mother liquor.

Method of producing naphthalenedicarboxylic acid

A process for the production of high-purity dimethyl 2,6-naphthalenedicarboxylate, which comprises esterifying 2,6-naphthalenedicarboxylic acid obtained by liquid phase oxidation of 2,6-dialkylnaphthalene with molecular oxygen in the presence of an oxidation catalyst, with methanol and then purifying a crude ester formed by the esterification, the crude ester being purified in the presence of an aromatic hydrocarbon as a solvent, in which impurities contained in a reaction product obtained by the esterification of 2,6-naphthalenedicarboxylic acid prepared by the liquid phase oxidation of 2,6-dialkylnaphthalene are effectively removed with simple procedures, oxidation catalyst metals are recovered, a crystal of naphthalenedicarboxylic acid formed by the oxidation of dialkylnaphthalene and/or its oxide derivative can be easily separated, and the oxidation catalyst to be brought into the step of producing dimethyl naphthalenedicarboxylate is recovered in the process of the production of naphthalenedicarboxylic acid and effectively used in the process of the production of naphthalenedicarboxylic acid.

Growing community of inventors

Okayama, Japan

Fumiya Zaima