Purifying a composition comprising (meth)acrylic acid, contaminant and water, comprises crystallizing (meth)acrylic acid and water, partially and completely melting the crystals of a crystal layer, and treating by layer crystallization

摘要

Purifying a composition comprising (meth)acrylic acid, at least a contaminant and water, comprises: (a) crystallizing (meth)acrylic acid and water from the composition to form a crystal layer comprising (meth)acrylic acid- and water crystals and depleted amount of contaminant; (b) removing the (meth)acrylic acid and water-depleted mother liquor of step (a) from the process stage and separating the crystal layer; (c) partially melting at least a portion of the crystals; (d) completely melting the purified crystal layer; and (e) treating by a layer crystallization according to steps (a)-(d). Purifying a composition comprising (meth)acrylic acid, at least a contaminant and water, where the composition has a water content of 0.55-90 wt.%, and the amount of the contaminant in the purified stage is less than 5 wt.%, comprises: (a) crystallizing (meth)acrylic acid and water from the composition under the formation of a crystal layer comprising (meth)acrylic acid- and water crystals and a further depleted amount of contaminant, where (meth)acrylic acid and water-depleted mother liquor is formed; (b) removing the mother liquor of step (a) from the process stage and separating the crystal layer; (c) partially melting at least a portion of the (meth)acrylic acid- and water crystals of the separated crystal layer to melts; (d) completely melting the purified crystal layer and separating the resulting product from the process stage; and (e) treating for further purification by a layer crystallization according to the steps (a)-(d). An independent claim is included for acrylic acid/(meth)acrylic acid, obtainable by the above method.