Sumitomo Chemical Company, Limited

Masami Ayano

Michio Kato

Tadashi Abe

Tetsuya Ohrui

Masao Sada

Masanori Moriwaki

Yasuhito Sakakibara

Yukinaga Aono

Hiroshi Takao

Tsunejiro Kawaguchi

A process for separation of methacrylic acid from a methacrylic acid-containing, gaseous reaction mixture obtained by subjecting methacrolein or a compound which can afford methacrolein under reaction conditions and molecular oxygen to gas phase reaction in the presence of a catalyst for oxidation under the coexistence of an inert gas for dilution which comprises (a) cooling the gaseous reaction mixture from a reactor wherein the gas phase reaction has been effected to separate into condensable components including methacrylic acid, acetic acid and water vapor as a condensed liquor and non-condensable components including methacrolein as a non-condensed gaseous mixture, (b) eliminating contaminating methacrolein from the condensed liquor and (c) contacting the resulting condensed liquor with an organic solvent to extract methacrylic acid, followed by separation into an organic solvent solution including methacrylic acid and an aqueous solution as waste water, characterized in that (1) the inert gas for dilution is a non-condensable gas or its mixture with water vapor and (2) the aqueous solution ultimately separated is evaporated and the evolved vapor is subjected to catalytic combustion with molecular oxygen, whereby the amount of waste water to be discharged is much suppressed.

Waste water treatment in the production of methacrylic acid

A process for purifying crude acrylic acid characterized in that high-purity purified acrylic acid containing little or no low boiling aldehydes is obtained by rectifying a crude acrylic acid consisting essentially of acrylic acid and containing low boiling substances such as acetaldehyde, acrolein, water and acetic acid and/or high boiling substances such as maleic acid, phenol, benzaldehyde and acrylic acid dimer, thereby removing said low boiling substances and then high boiling ones, and then stripping trace amounts of remaining low boiling aldehydes with an inert gas such as nitrogen or air at a liquid to gas molar ratio of 2 to 20.

Purification of crude acrylic acid

A method for extraction of acrylic acid and/or methacrylic acid from a solution containing the same by treating the said solution with an organic solvent, which is characterized by using a mixture of methylethylketone and a xylene as the organic solvent. By such method, the extraction of acrylic acid and/or methacrylic acid is accomplished efficiently and economically.

Extraction of acrylic acid and/or methacrylic acid with a solvent

Growing community of inventors

Saijo, Japan

Masami Ayano