METHOD OF PRODUCING ACRYLIC ACID Russian patent published in 2013 - IPC C07C57/07 B01D11/04 C07C51/25 C07C51/44 C07C51/48 C07C51/215 

FIELD: chemistry.

SUBSTANCE: conducting heterogeneously catalysed gas-phase partial oxidation of at least one corresponding starting compound with three carbon atoms on catalysts in a solid aggregative state at high temperature with molecular oxygen enables to obtain a gaseous mixture of products containing acrylic acid, water vapour and secondary components; if necessary, temperature of said mixture is lowered by direct and/or indirect cooling, after which said mixture is fed into a condensation column equipped with efficiently separating elements, wherein said mixture rises by itself along said column with simultaneous flow of fractional condensation. Through a first side outlet, which lies above the point of feeding the gaseous mixture of reaction products into the condensation column, crude acrylic acid poor in water and secondary components is output from the condensation column as the end product; through a second liquid phase outlet lying above the first side outlet, acid water containing acrylic acid and secondary components is output from the condensation column; a residual gaseous mixture containing secondary components which boil at a lower temperature than water is output from the top part of the condensation column; still liquor which contains acrylic acid, as well as byproducts and secondary components which boil at higher temperature than acrylic acid are output the bottom of the condensation column; part of the amount of the collected acid water as it is and/or after cooling is returned into the condensation column as reflux, and crude acrylic acid is optionally subjected to additional treatment using at least another thermal separation method, and, if necessary, part of the amount of collected acid water is added to acrylic acid before additional crystallisation treatment, where acrylic acid contained in at least part of the amount acid water which is not returned into the condensation column is transferred from the acid water to an organic solvent through extraction carried out by said solvent, which is accompanied by formation of an organic extract containing acrylic acid, from which acrylic acid is further separated by stripping thereof with a first stripping gas, wherein the first stripping gas containing acrylic acid is returned into the condensation column, and/or acrylic acid contained in the first stripping gas is transferred into an aqueous solution of a metal hydroxide or the formed first stripping gas which contains acrylic acid is used as a second stripping gas in order to strip acrylic acid contained in the still liquor output from the condensation column, and wherein the formed second stripping gas containing acrylic acid is returned into the condensation column and/or acrylic acid contained in the second stripping gas is transferred into an aqueous solution of a metal hydroxide.

EFFECT: improved method.

21 cl, 6 ex