Abstract: A method for producing acrylic acid, comprising (a) a absorption step of absorbing acrylic acid-containing gas obtained by oxidizing raw material gas in gas phase as crude acrylic acid-containing solution, (b1) a step of separating high boiling point components that separates the crude high boiling point components at a distillation column as (b) a step of purifying the acrylic acid-containing solution, and further, (c) a decomposition step of decomposing Michael adducts contained in the high boiling point components to prepare acrylic acid and (d) a collection step of collecting acrylic acid generated in the decomposition step (c), whereby the proportion of the amount of maleic acid to a sum of the sum of the maleic acid and maleic anhydride in the high boiling point components that are fed from the high boiling point component separation step (b1) to the decomposition step (c) satisfies a equation below: [ Equation ? ? 1 ] ? ` [ Maleic ? ? acid ? ? ( mass ) ] [

Abstract: A method for producing acrylic acid, comprising (a) a absorption step of absorbing acrylic acid-containing gas obtained by oxidizing raw material gas in gas phase as crude acrylic acid-containing solution, (b1) a step of separating high boiling point components that separates the crude high boiling point components at a distillation column as (b) a step of purifying the acrylic acid-containing solution, and further, (c) a decomposition step of decomposing Michael adducts contained in the high boiling point components to prepare acrylic acid and (d) a collection step of collecting acrylic acid generated in the decomposition step (c), whereby the proportion of the amount of maleic acid to a sum of the sum of the maleic acid and maleic anhydride in the high boiling point components that are fed from the high boiling point component separation step (b1) to the decomposition step (c) satisfies a equation below: [ Equation ? ? ? 1 ] ? ? ` [ Maleic ? ? ? acid ? ( mass ) ] [ Malei

Abstract: A method for the decomposition of a Michael type adduct, characterized by causing a Michael type adduct to react in the presence of an N-oxyl compound thereby decomposing the Michael type adduct into acrylic acid and/or the acrylic ester and/or the alcohol and a method for the production of acrylic acid and/or the acrylic ester, characterized by comprising a step of recovering a Michael type adduct formed in the process for the production of acrylic acid or acrylic ester and a step of decomposing the recovered Michael type adduct by the method of decomposition mentioned above. This invention, therefore, allows promotion of efficient utilization of the raw materials.

Abstract: A method for the decomposition of a Michael type adduct of an acrylic acid and/or an acrylic ester represented by the following formula [I] or [II] is disclosed, wherein decomposing the Michael type adduct in the presence of at least one copper salt and at least one metal salt selected from the group consisting of an alkali metal salt and an alkaline earth metal salt into an acrylic acid and/or an acrylic ester and/or an alcohol. CH2?CHCOO(—X—COO)n—R1??[I] R2—O(—X—COO)m—R3??[II] (wherein n and m denote an integer in the range of 1-5, R1, R2, and R3 independently denote a hydrogen atom or an alkyl group, and —X— denotes —CH2CH2— or —CH(CH3)—, and —X— may be identical or different when n is 2 or more).

Abstract: A method for the decomposition of a Michael type adduct of an acrylic acid and/or an acrylic ester represented by the following formula [I] or [II] is disclosed, wherein decomposing the Michael type adduct in the presence of at least one copper salt and at least one metal salt selected from the group consisting of an alkali metal salt and an alkaline earth metal salt into an acrylic acid and/or an acrylic ester and/or an alcohol.

Abstract: A method for the decomposition of a Michael type adduct, characterized by causing a Michael type adduct to react in the presence of an N-oxyl compound thereby decomposing the Michael type adduct into acrylic acid and/or the acrylic ester and/or the alcohol and a method for the production of acrylic acid and/or the acrylic ester, characterized by comprising a step of recovering a Michael type adduct formed in the process for the production of acrylic acid or acrylic ester and a step of decomposing the recovered Michael type adduct by the method of decomposition mentioned above. This invention, therefore, allows promotion of efficient utilization of the raw materials.

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 purification process for hydroxyalkyl (meth)acrylate that suppresses forming by-products such as a diester and a dimer of acrylic acid in the distillation process, and can ensure a purity of hydroxyalkyl (meth)acrylate, and can operate stably without causing troubles such as polymerization. In a purification process for hydroxyalkyl (meth)acrylate which is obtained by reacting (meth)acrylic acid and alkylene oxide in the presence of a catalyst, and removing unreacted alkylene oxide and/or (meth)acrylic acid in a reaction solution after the reaction, a distillation apparatus having a portion of a vacant column and a thin-film evaporation apparatus are used at the same time.

Abstract: An improved method which enables stable and effective recovery of acrylic acid over a prolonged period is provided, said method comprising contacting an acrylic acid-containing gas obtained upon gas-phase catalytic oxidation of propylene and/or acrolein, with water, whereby collecting the acrylic acid in form of an aqueous solution, introducing said aqueous solution into an azeotropic separation column and distilling it in the presence of an azeotropic solvent to isolate and recover the acrylic acid, in which polymerization of the acrylic acid in the azeotropic separation column is prevented. Said method is characterized by using as the azeotropic solvent either a mixed solvent composed of solvent A (eg., ethyl acrylate, methyl methacrylate, etc.) and solvent B (eg., toluene, heptane, etc.) (first embodiment) or the solvent A alone (second embodiment).