The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Dec. 08, 2015
Filed:
Jan. 06, 2013
Zhejiang Nhu Company Ltd., Shaoxing, Zhejiang Province, CN;
Zhejiang University, Hangzhou, Zhejiang Province, CN;
Shandong Nhu Amino Acids Co., Ltd., Weifang, Shandong Province, CN;
Zhirong Chen, Hangzhou, CN;
Cunchao Wang, Shaoxing, CN;
Chuqiu Zhao, Shaoxing, CN;
Sujuan Wang, Shaoxing, CN;
Chengfeng Zhang, Shaoxing, CN;
Tao Long, Shaoxing, CN;
Xinhong Liu, Shaoxing, CN;
ZHEJIANG NHU COMPANY LTD., Shaoxing, CN;
ZHEJIANG UNIVERSITY, Hangzhou, CN;
SHANDONG NHU AMINO ACIDS CO., LTD., Weifang, CN;
Abstract
The present invention discloses a clean method for preparing a D,L-methionine comprising the steps of: preparing a potassium cyanide solution using a crystallized mother solution containing potassium carbonate as an absorbing liquid to absorb hydrocyanic acid, then reacting the potassium cyanide solution with 3-methylthio propionaldehyde and an ammonium bicarbonate solution at 50-150° C. for 3-15 minutes so as to obtain a 5-(β-methylthioethyl)glycolyurea solution, then bring the 5-(β-methylthioethyl)glycolyurea solution to a temperature of 140-220° C. and subjecting to a saponification reaction for 2-5 minutes, after the completion of the saponification, reducing the temperature to 0-40° C., extracting with an organic solvent, neutralizing the water phase with COand crystallizing, then filtering, washing, and drying to obtain an acceptable D,L-methionine product; bring the crystallized D,L-methionine mother solution from filtration to a temperature to 110-160° C. to remove CO, which are all then circulated and used as a hydrocyanic acid-absorbing liquid. The process route of the present invention is a route suitable for a continuous and clean production, substantially without producing waste water and waste gas.