Abstract: The present invention provides a method capable of sufficiently reducing impurities with excellent separation efficiency even from a crystal-containing slurry that contains a low-purity mother liquor and has poor solid-liquid separation properties. The present invention relates to a method for producing a compound, the method including: a step of feeding a slurry containing crystals of the compound to a hydraulic wash column; a step of melting crystals in a crystal-containing circulation slurry discharged from the hydraulic wash column; and a step of returning a portion of a circulation liquid containing a melt obtained in the melting step to the hydraulic wash column, wherein the circulation liquid returned in the returning step in an amount of more than 30% by mass relative to 100% by mass of the melt serves as a washing liquid for crystals.

Abstract: Provided is a method for purifying a compound capable of providing a high purity compound in high yield and at low cost. The present invention relates to the method for purifying a compound using a purification apparatus, the purification apparatus including: a crystallizing unit including a crystal forming section; and a wash column including a mechanism that forcibly transfers crystals. The crystallizing unit includes N tanks connected in series, wherein N is 2 or greater, a 1st tank is a most downstream tank, a (N)th tank is a most upstream tank, at least the 1st tank is a crystallization tank including a cooling mechanism, and a 2nd and subsequent tanks are each a crystallization tank or a ripening tank. The purification apparatus includes a line that feeds a compound-containing liquid to be purified to at least one of the N tanks.

Abstract: The present invention aims to provide a compound purification apparatus capable of providing a high purity compound in high yield and at low cost.

Abstract: A method for producing (meth)acrylic acid comprising: a step of obtaining a (meth)acrylic acid-containing gas by subjecting a (meth)acrylic acid production raw material to a catalytic gas phase oxidation reaction; a step of obtaining a (meth)acrylic acid-containing liquid by bringing the (meth)acrylic acid-containing gas into contact with a collection solvent and/or condensing the (meth)acrylic acid-containing gas by cooling; a step of obtaining crude (meth)acrylic acid by introducing the (meth)acrylic acid-containing liquid into a low-boiling separation column; a step of obtaining purified (meth)acrylic acid and a refining residue containing a glyoxal compound by purifying the crude (meth)acrylic acid; and a step of returning at least a part of the refining residue to the low-boiling separation column; wherein a returning position of the refining residue to the low-boiling separation column is located closer to a bottom side of the low-boiling separation column than a supply port of the (meth)acrylic acid-co

Abstract: A method for producing (meth)acrylic acid comprising: a step of obtaining a (meth)acrylic acid-containing gas by subjecting a (meth)acrylic acid production raw material to a catalytic gas phase oxidation reaction; a step of obtaining a (meth)acrylic acid-containing liquid by bringing the (meth)acrylic acid-containing gas into contact with a collection solvent and/or condensing the (meth)acrylic acid-containing gas by cooling; a step of obtaining crude (meth)acrylic acid by introducing the (meth)acrylic acid-containing liquid into a low-boiling separation column; a step of obtaining purified (meth)acrylic acid and a refining residue containing a glyoxal compound by purifying the crude (meth)acrylic acid; and a step of returning at least a part of the refining residue to the low-boiling separation column; wherein a returning position of the refining residue to the low-boiling separation column is located closer to a bottom side of the low-boiling separation column than a supply port of the (meth)acrylic acid-co

Abstract: The objective of the present invention is to provide a method for efficiently producing acrylic acid while troubles not only in a waste oil handling after distillation of acrylic acid but also in a purification system of acrylic acid during distillation are reduced. The method for producing acrylic acid according to the present invention is characterized in comprising the step of supplying at least crude acrylic acid and an alcohol solvent to an acrylic acid distillation apparatus to distill acrylic acid, wherein a boiling point of the alcohol solvent is higher than a boiling point of acrylic acid by not lower than 50° C.

Abstract: The objective of the present invention is to provide a method for efficiently producing acrylic acid while troubles not only in a waste oil handling after distillation of acrylic acid but also in a purification system of acrylic acid during distillation are reduced. The method for producing acrylic acid according to the present invention is characterized in comprising the step of supplying at least crude acrylic acid and an alcohol solvent to an acrylic acid distillation apparatus to distill acrylic acid, wherein a boiling point of the alcohol solvent is higher than a boiling point of acrylic acid by not lower than 50° C.

Abstract: The present invention provides a method for manufacturing a water-absorbing resin which (i) is made of acrylic acid that is suitable for mass production of water-absorbing resin and (ii) has an excellent water-absorbing property. In the method, a polyacrylic acid (salt)-based water-absorbing resin is manufactured by sequentially carrying out predetermined monomer preparing step, polymerization step, drying step, and surface crosslinking step. An acetic acid concentration in acrylic acid or the like supplied in the monomer preparing step is in a range of 300 ppm to 10000 ppm on the acrylic acid basis, and an acetic acid concentration lowering rate defined by a predetermined formula is 35% or higher.

Abstract: A process for producing (meth)acrylic acid comprising the step of repeating a crystallization operation “n” times to produce purified (meth)acrylic acid from crude (meth)acrylic acid, wherein: the each crystallization operation comprises a crystallizing step and a melting step; a polymerization inhibitor is not added to a (meth)acrylic acid melt obtained in the melting step of the first to n?1th crystallization operation(s) and a (meth)acrylic acid solution subjected to the crystallizing step of the second to nth crystallization operation(s); and a concentration of a polymerization inhibitor in a (meth)acrylic acid solution subjected to the crystallizing step of the first crystallization operation is adjusted so that a concentration of the polymerization inhibitor in a (meth)acrylic acid solution subjected to the crystallizing step of the nth crystallization operation is 2 ppm by mass or higher.

Abstract: The present invention provides a method for manufacturing a water-absorbing resin which (i) is made of acrylic acid that is suitable for mass production of water-absorbing resin and (ii) has an excellent water-absorbing property. In the method, a polyacrylic acid (salt)-based water-absorbing resin is manufactured by sequentially carrying out predetermined monomer preparing step, polymerization step, drying step, and surface crosslinking step. An acetic acid concentration in acrylic acid or the like supplied in the monomer preparing step is in a range of 300 ppm to 10000 ppm on the acrylic acid basis, and an acetic acid concentration lowering rate defined by a predetermined formula is 35% or higher.

Abstract: A process for producing (meth)acrylic acid comprising the step of repeating a crystallization operation “n” times to produce purified (meth)acrylic acid from crude (meth)acrylic acid, wherein: the each crystallization operation comprises a crystallizing step and a melting step; a polymerization inhibitor is not added to a (meth)acrylic acid melt obtained in the melting step of the first to n?1th crystallization operation(s) and a (meth)acrylic acid solution subjected to the crystallizing step of the second to nth crystallization operation(s); and a concentration of a polymerization inhibitor in a (meth)acrylic acid solution subjected to the crystallizing step of the first crystallization operation is adjusted so that a concentration of the polymerization inhibitor in a (meth)acrylic acid solution subjected to the crystallizing step of the nth crystallization operation is 2 ppm by mass or higher.

Abstract: The present invention provides a method for effectively preventing the precipitation related to manganese acetate in the pipe for sending a polymerization inhibitor and the like, and the polymerization of (meth)acrylic acid. A first method of the present invention for producing (meth)acrylic acid, characterized in comprising steps of: producing a (meth)acrylic acid-containing gas by catalytic vapor phase oxidation reaction; and obtaining a (meth)acrylic acid-containing fluid by providing the (meth)acrylic acid-containing gas into a condensation column or an absorption column; wherein manganese acetate is used as a polymerization inhibitor; manganese acetate is dissolved into a (meth)acrylic acid aqueous solution containing not more than 10% by mass of (meth)acrylic acid, and the like, to obtain a manganese acetate aqueous solution; and the manganese acetate aqueous solution is provided into the condensation column or the absorption column.

Abstract: The present invention provides a method for effectively preventing the precipitation related to manganese acetate in the pipe for sending a polymerization inhibitor and the like, and the polymerization of (meth)acrylic acid. A first method of the present invention for producing (meth)acrylic acid, characterized in comprising steps of: producing a (meth)acrylic acid-containing gas by catalytic vapor phase oxidation reaction; and obtaining a (meth)acrylic acid-containing fluid by providing the (meth)acrylic acid-containing gas into a condensation column or an absorption column; wherein manganese acetate is used as a polymerization inhibitor; manganese acetate is dissolved into a (meth)acrylic acid aqueous solution containing not more than 10% by mass of (meth)acrylic acid, and the like, to obtain a manganese acetate aqueous solution; and the manganese acetate aqueous solution is provided into the condensation column or the absorption column.

Abstract: There is provided a process for producing (meth)acrylic acid including an absorption step of bringing a (meth)acrylic acid-containing gas obtained by a gas phase catalytic oxidation method into an absorption tower and allowing the gas to contact with an absorbent, in which absorption step a crude (meth)acrylic acid solution is withdrawn from a withdrawal outlet positioned between a supply point for the (meth)acrylic acid-containing gas and a supply point for the absorbent on the absorption tower, and then supplied to a next step. The process for producing (meth)acrylic acid makes it possible to suppress the formation of Michael adducts, thereby obtaining a (meth)acrylic acid containing solution in high yield and in high concentration.

Abstract: There is provided a process for producing (meth)acrylic acid including an absorption step of bringing a (meth)acrylic acid-containing gas obtained by a gas phase catalytic oxidation method into an absorption tower and allowing the gas to contact with an absorbent, in which absorption step a crude (meth)acrylic acid solution is withdrawn from a withdrawal outlet positioned between a supply point for the (meth)acrylic acid-containing gas and a supply point for the absorbent on the absorption tower, and then supplied to a next step. The process for producing (meth)acrylic acid makes it possible to suppress the formation of Michael adducts, thereby obtaining a (meth)acrylic acid containing solution in high yield and in high concentration.