摘要:
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, Br− conversion, 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.
摘要:
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medium is mainly discharged from the lower portion of the replacement tank, and the first dispersion medium is mainly withdrawn from the upper portion of the replacement tank.
摘要:
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.
摘要:
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.
摘要:
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.
摘要:
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.
摘要:
A process for producing a hydrogenation product of aromatic carboxylic acid which comprises continuously producing the hydrogenation product of aromatic carboxylic acid by hydrogenating an aromatic carboxylic acid having a melting point of 250° C. or higher in a solvent in the presence of a solid catalyst, wherein the hydrogenation is conducted in a condition such that substantially the entire amount of the aromatic carboxylic acid of a raw material is dissolved in the solvent by recycling a portion of a reaction liquid taken out of a reactor into the reactor. An aromatic carboxylic acid having a high melting point and hardly soluble in solvents can be hydrogenated at a suitable reaction temperature in accordance with a continuous process without using a great amount of a solvent and the reaction product of the object compound can be produced very efficiently.
摘要:
There is disclosed a process for producing highly pure terephthalic acid by converting a slurry of terephthalic acid crystals in acetic acid solvent which crystals are obtained by liquid-phase oxidation of p-alkylbenzene, into a slurry thereof in water solvent by mother liquor replacement and then subjecting the latter slurry to a catalytic hydrogenation treatment which process comprises the steps of introducing the slurry of terephthalic acid crystals in acetic acid into a mother liquor replacement column at the top portion; forming an accumulation layer of the terephthalic acid crystals at the bottom portion by the sedimentation of the crystals; feeding replacing water sufficient for the formation of upward rising stream of water to the inside of the column at the bottom portion; and withdrawing the accumulation layer of the crystals from the bottom portion of the column. The accumulation layer is kept at a slightly fluidized stable state and is smoothly withdrawn from the bottom of the column by slowly rotating an arm-type agitation blade placed in the layer or by feeding the replacing water dividedly into two trains.
摘要:
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.
摘要:
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.