Abstract: A method for producing acrylic acid by using an acrylic acid-containing solution of high concentration without azeotropic distillation is provided. This method of producing acrylic acid comprises introducing an acrylic acid-containing gas obtained by catalytic gas phase oxidation reaction into an absorption column and supplying the acrylic acid-containing solution to crystallization step thereby separating the solution into acrylic acid and residual mother liquid, and distilling at least part of the residual mother liquid and circulating the distillate obtained by the distillation to the absorption column.

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: An apparatus for the preparation and supply of a polymerization inhibitor which constantly effects stable supply of a polymerization inhibitor solution adjusted to a prescribed concentration and enables a compound handled at the next step to be prevented from polymerization is provided. The apparatus for the preparation and supply of a polymerization inhibitor has at least two tanks and a stirring device, a liquid level detector, a polymerization inhibitor input port, a concentration-adjusting liquid input port, and a polymerization inhibitor solution feed opening, each being installed in at least one of said tanks.