Abstract: The present invention provides a method for efficiently using an aqueous solution of (meth)acrylic acid at a low concentration formed in a production/storage step of (meth)acrylic acid. In the present invention, a (meth)acrylic acid derivative is produced by using as a raw material an aqueous solution of (meth)acrylic acid formed by one or both of: a device which reduces a pressure of a gas comprising (meth)acrylic acid in production of (meth)acrylic acid; and a device which collects (meth)acrylic acid from a gas comprising (meth)acrylic acid.

Abstract: A method of storing (meth)acrylate in a tank of a less expensive and highly versatile material without losing stability of the stored (meth)acrylate. To be specific, a method of storing (meth)acrylate in a tank, including supplying an appropriate gas for storing (meth)acrylate into the tank, in which: the tank is made of a carbon steel material; the gas has a water concentration of 100 ppm or less; and the (meth)acrylate has a (meth)acrylic acid concentration of 30 ppm or less.

Abstract: (Meth)acrolein or (meth)acrylic acid is collected by bringing a reaction gas (1) containing (meth)acrolein or (meth)acrylic acid obtained through a vapor-phase catalytic oxidation reaction into contact with an aqueous solution as a collecting solvent in a collecting tower main body (2). The reaction gas (1) is supplied to the collecting tower main body (2) from two nozzles (2c) facing each other, and is caused to collide in the collecting tower main body (2). According to the present invention, (meth)acrolein or (meth)acrylic acid can be efficiently collected from a gas containing (meth)acrolein or (meth)acrylic acid while preventing polymerization.

Abstract: A producing method of (meth)acrolein or (meth)acrylic acid where by use of a multi-tubular reactor that has a plurality of reaction tubes filled with a catalyst, catalytic gas phase oxidation of propylene, propane, isobutylene or (meth)acrolein is carried out in the presence of a composite oxide catalyst by use of molecular oxygen or a gas containing molecular oxygen, in which method (meth)acrolein or (meth)acrylic acid can be obtained stably in high yield for a long period of time without allowing the activity of the catalyst to decrease locally (disproportionately) and extremely. A temperature difference between a temperature of a heat medium at the beginning of operation and a peak temperature of the catalyst is set in a range of 20 to 80° C., and during operations a change of the peak temperature T of the catalyst in a tube axis direction is maintained in a definite range.

Abstract: The object of this invention is to provide a method of maintaining a multi-tubular reactor which can ensure the uniformity of states of reaction in the reaction tubes in the multi-tubular reactor. This invention is a method of maintaining a multi-tubular reactor in good condition by selecting a part of reaction tubes in a multi-tubular reactor at random, measuring a differential pressure occurring in each reaction tube when passing gas therethrough, separating any reaction tube showing an abnormal differential pressure as compared with the average of differential pressures in reaction tubes packed with an fresh catalyst of the same kind, giving adequate treatment to the separated reaction tube and returning it into the reactor with any other selected reaction tube falling within a normal range.

Abstract: A decomposition reaction apparatus or distillation apparatus for acrylic acid in which a column bottom liquid heated in a reboiler (5) is supplied from a supply port (1a) provided on a side wall of a column body (1) having: a top plate (12a) above the supply port (1a); and an impingement plate (12b) provided vertically to the top plate (12a), for preventing scattering of the column bottom liquid to a supply direction. The top plate (12a) is provided such that the top face of the top plate (12a) is inclined downward from a base end to a tip end. The present invention allows: suppression of formation of a polymerized product due to flowing of a liquid or gas heated in a reboiler into a column with a simple structure; and a stable continuous operation of column equipment over a long period of time.

Abstract: A distillation apparatus for subjecting a crude readily polymerizable compound to distillation under vacuum conditions to purify it, the distillation apparatus having a distillation column and a vacuum generator and an exhaust gas conduit of the vacuum generator connected to a connecting conduit therebetween through a pressure control valve. A method provides purifying of a readily polymerizable compound by subjecting a crude readily polymerizable compound to distillation under vacuum conditions to purify it, the method including using a distillation apparatus having a distillation column and a vacuum generator and an exhaust gas conduit of the vacuum generator connected to a connecting conduit therebetween through a pressure control valve and controlling the action of the pressure control valve based on a pressure of the distillation column.

Abstract: The object of this invention is to provide a method of maintaining a multi-tubular reactor which can ensure the uniformity of states of reaction in the reaction tubes in the multi-tubular reactor. This invention is a method of maintaining a multi-tubular reactor in good condition by selecting a part of reaction tubes in a multi-tubular reactor at random, measuring a differential pressure occurring in each reaction tube when passing gas therethrough, separating any reaction tube showing an abnormal differential pressure as compared with the average of differential pressures in reaction tubes packed with an fresh catalyst of the same kind, giving adequate treatment to the separated reaction tube and returning it into the reactor with any other selected reaction tube falling within a normal range.

Abstract: A method for purifying a crude (meth)acrylic acid obtained by a vapor phase catalytic oxidation method, characterized in that the crude (meth)acrylic acid having most parts of water and acetic acid removed therefrom, is fed to and distilled in a first distillation column of a purification system comprising first to third three distillation columns, the top fraction from the first distillation column is fed to and distilled in the second distillation column, the resulting top fraction is recovered as a high purity (meth)acrylic acid product, the bottoms from the first and second distillation columns are fed to and distilled in the third distillation column, and the resulting top fraction is fed to the first distillation column.

Abstract: The present invention provides a method for efficiently using an aqueous solution of (meth)acrylic acid at a low concentration formed in a production/storage step of (meth)acrylic acid. In the present invention, a (meth)acrylic acid derivative is produced by using as a raw material an aqueous solution of (meth)acrylic acid formed by one or both of: a device which reduces a pressure of a gas comprising (meth)acrylic acid in production of (meth)acrylic acid; and a device which collects (meth)acrylic acid from a gas comprising (meth)acrylic acid.

Abstract: An object of the present invention is to provide a method for producing (meth)acrylic acid or (meth)acrolein by conducting a gas phase catalytic oxidation reaction with an oxygen-containing gas using as a raw material at least one substance to be oxidized selected from propylene, propane, isobutylene and (meth)acrolein using a multi-tubular reactor, which enables a high yield and stable production even when operating constantly with supplying the raw material in the maximum supply amount acceptable by the reactor or an amount close thereto. The invention is a method for producing (meth)acrylic acid or (meth)acrolein wherein, at the time of a start-up of the reaction, for a period of at least 20 hours or more after the supply amount of the raw material to the reactor per unit time reached 30% or more of the acceptable maximum supply amount of the raw material per unit time, the supply amount of the raw material per unit time is kept at 30% or more and less than 80% of the acceptable maximum supply amount.

Abstract: A method for purifying a crude (meth)acrylic acid obtained by a vapor phase catalytic oxidation method, characterized in that the crude (meth)acrylic acid having most parts of water and acetic acid removed therefrom, is fed to and distilled in a first distillation column of a purification system comprising first to third three distillation columns, the top fraction from the first distillation column is fed to and distilled in the second distillation column, the resulting top fraction is recovered as a high purity (meth)acrylic acid product, the bottoms from the first and second distillation columns are fed to and distilled in the third distillation column, and the resulting top fraction is fed to the first distillation column.

Abstract: In the stopping and starting operations of a distillation column used for producing (meth)acrylic acids according to the present invention, upon stopping the operation of the distillation column, the heating of a reboiler attached thereto is interrupted and then the reboiler is rapidly cooled; and/or upon starting the operation of the distillation column for production of the (meth)acrylic acids, an inner wall surface of the distillation column is heated to a temperature higher than a condensation temperature of the (meth)acrylic acids and the operation of the distillation column is started under the heated condition. According to the present invention, it is possible to early and safely stop the operation of the distillation column while preventing the occurrence of polymerization within the distillation column, and stably perform an operation for distillation of acrylic monomers for a long period of time.

Abstract: The present invention reduces a cost of a polymerization inhibitor required in purification of high purity acrylic acid through distillation. According to the present invention, a condensate obtained through the distillation of acrylic acid in a distillation column is fed to a flasher, to thereby obtain acrylic acid as a product from a distillate distilled from the flasher.

Abstract: In the stopping and starting operations of a distillation column used for producing (meth)acrylic acids according to the present invention, upon stopping the operation of the distillation column, the heating of a reboiler attached thereto is interrupted and then the reboiler is rapidly cooled; and/or upon starting the operation of the distillation column for production of the (meth)acrylic acids, an inner wall surface of the distillation column is heated to a temperature higher than a condensation temperature of the (meth)acrylic acids and the operation of the distillation column is started under the heated condition. According to the present invention, it is possible to early and safely stop the operation of the distillation column while preventing the occurrence of polymerization within the distillation column, and stably perform an operation for distillation of acrylic monomers for a long period of time.

Abstract: A process for producing (meth)acrylic acid or (meth)acrylic acid esters, which comprises a reaction step comprising vapor phase catalytic oxidation of propylene, propane or isobutylene and, if necessary, a reaction step comprising an esterification step, characterized in that at the time when a high boiling mixture (hereinafter referred to as a high boiling material) containing a Michael addition product, is decomposed in a decomposition reactor to recover (meth)acrylic acids, while forcibly imparting a liquid flow in the circumferential direction to a liquid reaction residue in the decomposition reactor, the liquid reaction residue is discharged. In a process for recovering a valuable substance by thermally decomposing the high boiling material containing the Michael addition product of (meth)acrylic acids, it is possible to transfer the decomposition residue from the decomposition reactor to the storage tank without clogging, whereby a long-term continuous operation is possible.

Abstract: The object of the invention is to provide a method for producing (meth)acrylic acid or (meth)acrolein from at least one of propylene, propane, isobutylene and (meth)acrolein as a raw material by carrying out its gas phase catalytic oxidation reaction with molecular oxygen or a molecular oxygen-containing gas using a multi-tubular reactor, which is a method that can be operated more safely by feeding a gas prepared in advance by mixing the raw material with molecular oxygen or a molecular oxygen-containing gas safely into the reactor by controlling generation and propagation of fire. The invention is a method for producing (meth)acrylic acid or (meth)acrolein, characterized in that a mixed gas formed by mixing the aforementioned raw material with the aforementioned molecular oxygen or a molecular oxygen-containing gas is fed into the aforementioned reactor via a piping equipped with a flame arrester.

Abstract: The present invention relates to a method of storing (meth)acrylate in a tank of a less expensive and highly versatile material without losing stability of the stored (meth)acrylate. To be specific, the present invention relates to a method of storing (meth)acrylate in a tank, including supplying an appropriate gas for storing (meth)acrylate into the tank, in which: the tank is made of a carbon steel material; the gas has a water concentration of 100 ppm or less; and the (meth)acrylate has a (meth) acrylic acid concentration of 30 ppm or less.

Abstract: An object of the present invention is to provide a pilot test method for suitably setting the reaction conditions for a gas-phase catalytic reaction using a multi-tube reactor, and an apparatus thereof.

Abstract: A method of decomposing a Michael addition reaction product formed as a by-product in the production step of a(meth)acrylic ester and recovering (meth)acrylic acid, a (meth)acrylic ester and an alcohol, in which the formation of an olefin as a by-product can be suppressed. A method of thermally decomposing a by-product at the time of production of a (meth)acrylic ester using an alcohol bearing a branched chain and having 3 or more carbon atoms, wherein the decomposition reaction is carried out in the absence of a catalyst.