Abstract: The present invention provides an industrially easy and economical method for purification of acrylic acid which enables to efficiently eliminate impurities from a crude acrylic acid containing aldehydes as the impurities while the formation of acrylic acid polymer is inhibited. The method for purification of acrylic acid includes the step of distilling a crude acrylic acid which is charged with an aldehyde treatment chemical, wherein the concentration ratio of furfural to acrolein by weight in the crude acrylic acid is adjusted so as to satisfy the following equation: (furfural concentration by weight)/(acrolein concentration by weight)?100.

Abstract: The present invention provides an apparatus for producing (meth)acrylic acid and a process for producing (meth)acrylic acid with this apparatus wherein the apparatus enables the production of (meth)acrylic acid stably for a long period of time by effectively inhibiting the polymerization of (meth)acrylic acid in its production process (for example, in a reboiler). At least a part of the apparatus is made of a nickel-chromium-iron alloy with a molybdenum content of 3 to 20 mass %, but not including 3 mass %, or with a molybdenum content of 1 to 4 mass % and a copper content of 0.5 to 7 mass %.

Abstract: A method for distilling a raw material liquid containing (meth)acrylic acid substantially free from azeotropic solvents, collected with a collection agent from a mixed gas obtained by gas phase catalytic oxidation reactions which includes feeding to a distillation column the raw material liquid which temperature is substantially equal to that of the entrance place in the column.

Abstract: To sufficiently stabilize a hydroxyalkyl (meth)acrylate in spite of its easily polymerizable property, a hydroxyalkyl saturated-carboxylate and/or alkylene glycol as well as a phenol compound is added thereto.

Abstract: A method for the production of (meth)acrylic acid and/or a (meth)acrylic ester is provided. This method for the production of (meth)acrylic acid and/or a (meth)acrylic ester includes washing the device constructed for the production thereof with a basic solution and subsequently rinsing them with a solvent for the purpose of removing solid substances such as polymer and precipitate which occur during the production of (meth)acrylic acid and/or a (meth)acrylic ester.

Abstract: A method for inhibiting polymerization during transportation, storage and/or production of (meth)acrylic acid or an ester thereof includes adding an N-oxyl compound and water to a vinyl compound; or dissolving an N-oxyl compound in water and adding the solution to a vinyl compound in a process of recovering, purifying, and/or synthesizing of the vinyl compound. The method can effectively inhibit polymerization of the vinyl compound.

Abstract: The present invention provides a process for producing a (meth)acrylic ester which enables to obtain a (meth)acrylic ester in an excellent reaction yield. The process for producing a (meth)acrylic ester uses an alcohol and an acid as raw materials and an ion-exchange resin as a catalyst, and the process is characterized by comprising a dehydration step and an esterification step, wherein the esterification reaction step follows the dehydration step in which water impregnated in the ion-exchange resin is removed by using as a dehydrating solvent at least one member selected from the group consisting of the alcohol, the acid, and the resulting ester.

Abstract: The present invention provides a column treating method by use of a distillation column and so on, which method enables to effectively remove solid impurities such as precipitates and polymers contained or produced in a treating fluid, and to thereby stably operate the column treatment. Solid impurities in a treating fluid can be removed by carrying out: step (a) of drawing out the treating fluid from a drawing out outlet (16) at the column bottom of the treatment column (10) outside the treatment column (10), step (b) of removing solid impurities from the treating fluid, drawn out in step (a), by a strainer (40), and step (c) of returning the treating fluid, from which the solid impurities are removed in step (b), to a returning inlet (18) of the treatment column, with advancing physical and/or chemical treatment of the treating fluid in the treatment column (10).

Abstract: An improvement is provided in a method for preparing an (meth)acrylic acid ester comprising an esterification step for forming the (meth)acrylic acid ester by esterification reaction between (meth)acrylic acid and the corresponding aliphatic alcohol having 1 to 4 carbon atoms in the presence of an acidic catalyst, and a separation-purification step comprising an acid-separating column, a low boiling matter-separating column and a rectification column for separating and purifying the (meth)acrylic acid ester from the (meth)acrylic acid ester-containing mixture obtained in the esterification step. This improvement lies in that by circulating the bottom residue of the rectification column into the esterification step and/or the separation-purification step, the remaining polymerization inhibitor in the bottom residue is effectively reused and the remaining (meth)acrylic acid ester in the bottom residue is efficiently recovered.

Abstract: This invention relates to a method for preventing (meth)acrylic acid from polymerizing during the course of distillation. The method provides for refining (meth)acrylic acid by a procedure including the steps of feeding a mixed gas obtained by catalytic gas phase oxidation of propylene and/or acrolein with a molecular oxygen-containing gas or a mixed gas obtained by catalytic gas phase oxidation of at least one compound of isobutylene, t-butyl alcohol, or methacrolein with a molecular oxygen-containing gas, to a (meth)acrylic acid collection column, collecting a (meth)acrylic acid-containing solution from the mixed gas, and feeding the (meth)acrylic acid-containing solution to a distillation column while maintaining the total concentration of aldehydes of 2-4 carbon atoms and acetone in the solution at a level of not more than 2000 ppm based on the amount of (meth)acrylic acid.

Abstract: The present invention provides a column treating method by use of a distillation column and so on, which method enables to effectively remove solid impurities such as precipitates and polymers contained or produced in a treating fluid, and to thereby stably operate the column treatment. Solid impurities in a treating fluid can be removed by carrying out: step (a) of drawing out the treating fluid from a drawing out outlet (16) at the column bottom of the treatment column (10) outside the treatment column (10), step (b) of removing solid impurities from the treating fluid, drawn out in step (a), by a strainer (40), and step (c) of returning the treating fluid, from which the solid impurities are removed in step (b), to a returning inlet (18) of the treatment column, with advancing physical and/or chemical treatment of the treating fluid in the treatment column (10).

Abstract: A method of producing highly purified acrylic acid in a high yield is provided. A method of producing acrylic acid including the steps of an oxidation step, an absorption step, a distillation step, a crystallization step, and a dimer decomposition step.

Abstract: The present invention provides an apparatus for producing (meth)acrylic acid and a process for producing (meth)acrylic acid with this apparatus wherein the apparatus enables to produce (meth)acrylic acid stably for a long period of time by effectively inhibiting the polymerization of (meth)acrylic acid in its production process (for example, in a reboiler). At least a part of the apparatus is made of a nickel-chromium-iron alloy with a molybdenum content of 3 to 20 mass %, but not including 3 mass %, or with a molybdenum content of 1 to 4 mass % and a copper content of 0.5 to 7 mass %.

Abstract: A method for washing a spent solid catalyst is disclosed which is characterized by washing the solid catalyst used for the reaction of generating an esterified compound in a device packed with the solid catalyst, distilling the cleaning fluid in a distilling part, and circulating the fraction obtained by the distillation to an esterification reactor. According to this invention, the existing apparatus used during the process for the production of an esterified compound can be adopted without any modification, the water by-produced in the reaction for production an esterified compound and an alcohol as the raw material for esterification can be used as the cleaning fluid, and these effective components can be recovered from the cleaning fluid. Thus, the stimulation from the offensive odor and the volatile component which has heretofore posed a problem during the removal of the solid catalyst is eliminated and the safety in terms of heath and in terms of operation is secured.

Abstract: A production process for a hydroxyalkyl(meth)acrylate, which comprises the steps of carrying out a reaction between (meth)acrylic acid and an alkylene oxide and stripping the unreacted residue of the alkylene oxide from the resultant reaction liquid, wherein: (1) the stripping step is performed by use of an inert gas, and the concentration of oxygen in the inert gas is adjusted in the range of 0.

Abstract: A method for distilling a raw material liquid containing (meth)acrylic acid substantially free from azeotropic solvents, collected with a collection agent from a mixed gas obtained by gas phase catalytic oxidation reactions which includes feeding to a distillation column the raw material liquid which temperature is substantially equal to that of the entrance place in the column.

Abstract: The present invention provides a production process for a hydroxyalkyl (meth)acrylate which process enables to maintain the oxygen concentration of a gas phase portion of a reactor within a specific low concentration range in any stage of before adding raw materials, during the reaction, and after the reaction. The production process comprises the step of carrying out a reaction between (meth)acrylic acid and an alkylene oxide in the presence of a catalyst in order to produce the hydroxyalkyl (meth)acrylate, wherein an inert gas and/or a mixed gas of oxygen and an inert gas with a beforehand adjusted oxygen concentration of 0.1 to 14 vol % is used to maintain the oxygen concentration of a gas phase portion of a reactor in the range of 0.1 to 14 vol % (1) before adding the alkylene oxide or (2) during the above reaction or (3) between the completion of the above reaction and the charge for the next reaction.

Abstract: The present invention provides an apparatus for producing (meth)acrylic acid and a process for producing (meth)acrylic acid with this apparatus wherein the apparatus enables to produce (meth)acrylic acid stably for a long period of time by effectively inhibiting the polymerization of (meth)acrylic acid in its production process (for example, in a reboiler). At least a part of the apparatus is made of a nickel-chromium-iron alloy with a molybdenum content of 3 to 20 mass %, but not including 3 mass %, or with a molybdenum content of 1 to 4 mass % and a copper content of 0.5 to 7 mass %.

Abstract: The present invention provide a production process for a hydroxyalkyl ester which comprises the step of carrying out a reaction between a carboxylic acid and an alkylene oxide in the presence of a catalyst, wherein the production process sufficiently enhances the conversion or selectivity in the reaction. The production process is characterized in that the reaction is carried out in a reaction liquid under conditions where a relationship a<b is kept throughout the reaction wherein “a” is a molar concentration (mol %) of the carboxylic acid in the reaction liquid and wherein “b” is a molar concentration (mol %) of the alkylene oxide in the reaction liquid.

Abstract: The present invention provides a method for stabilizing waste oil which is taken of each chemical apparatus of the manufacturing line of (meth)acryl acid and/or ester thereof, and treating the waste oil such as draining it out of the production apparatus, for example, a distillation tower from its bottom, sending and transporting it by a pump through a pipeline, and storing it in a storage tank in a simple manner while keeping the waste oil in a stable state. The waste oil can be stabilized by coexisting with solvent. The solvent used in the present invention is typically at least one selected from the group consisting of water, alcohol, ether, carboxylic acid, ketone, aromatic hydrocarbons, and aliphatic hydrocarbons.