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US 6,642,414 B2Granted
Method for production of (meth) acrylic acid
AssigneeNippon Shokubai Co., Ltd.
InventorsTetsuji Mitsumoto, Yukihiro Matsumoto, Sei Nakahara, Tatsuaki Yoshimura
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Abstract
A method for producing (meth)acrylic acid of high purity by repressing formation of a polymer possibly generated during the course of production is disclosed. The production is accomplished by returning the waste liquid generated at the step of the addition of aldehyde treating agents (d) to the step of the absorption (b) and/or the step of separation (c).
Claims20
A method for producing (meth)acrylic acid, which comprising:
- (a) a step of obtaining a gaseous reaction product containing (meth)acrylic acid by subjecting at least one member selected from the group consisting of propylene, propane, acrolein, and a mixture thereof or at least one member selected from the group consisting of isobutylene, t-butyl alcohol, methyl-t-butyl ether, methacrolein, and a mixture thereof to the reaction of catalytic gas phase oxidation;
- (b) a step of absorbing the gaseous reaction product by the use of a solvent;
- (c) a step of separating said solvent, a low boiling impurity, and a high boiling impurity from the (meth)acrylic acid solution absorbed with said solvent by extraction and/or distillation and obtaining crude (meth)acrylic acid solution containing aldehydes having boiling points approximating closely to the boiling point of(meth) acrylic acid as impurities;
- (d) a step of adding an aldehyde treating agent to said crude (meth)acrylic acid and subjecting the resultant mixture to vacuum distillation thereby obtaining (meth)acrylic acid of high purity;
- and
- (e) a step of returning the waste liquid generated in said step (d) to said step (b) and/or said step (c).
3 more elements
Dependencies are inferred from the claim text.