US 11,884,632 B2
Preparation method of caprolactam
Shibiao Cheng, Zhejiang (CN); Songlin Wang, Zhejiang (CN); Xi Li, Zhejiang (CN); Han Wang, Zhejiang (CN); Fei Shen, Zhejiang (CN); Xinping Zhang, Zhejiang (CN); Zhaobin Jiang, Zhejiang (CN); and Zhimin Hu, Zhejiang (CN)
Assigned to ZHEJIANG HENGYI PETROCHEMICAL RESEARCH INSTITUTE CO., LTD., Hangzhou (CN)
Filed by ZHEJIANG HENGYI PETROCHEMICAL RESEARCH INSTITUTE CO., LTD., Hangzhou (CN)
Filed on Mar. 25, 2021, as Appl. No. 17/212,530.
Claims priority of application No. 202010911945.4 (CN), filed on Sep. 2, 2020.
Prior Publication US 2022/0064124 A1, Mar. 3, 2022
Int. Cl. C07D 223/10 (2006.01); C07D 201/06 (2006.01); C07D 201/16 (2006.01); B01J 29/70 (2006.01); B01J 35/08 (2006.01); B01J 37/00 (2006.01); B01J 37/04 (2006.01); B01J 37/08 (2006.01)
CPC C07D 223/10 (2013.01) [B01J 29/70 (2013.01); B01J 35/08 (2013.01); B01J 37/0036 (2013.01); B01J 37/04 (2013.01); B01J 37/08 (2013.01)] 21 Claims
 
1. A method for preparing caprolactam comprising the following steps:
(1) contacting cyclohexanone oxime with a catalyst to carry out reaction in the presence of ethanol and under the condition of gas phase Beckmann rearrangement reaction of cyclohexanone oxime;
(2) separating the reaction product obtained in step (1) to produce an ethanol solution of crude caprolactam, and then separating the ethanol solution of crude caprolactam to obtain ethanol and crude caprolactam;
(3) removing impurities with boiling points lower than that of caprolactam in the crude caprolactam to obtain a light component removal product;
(4) mixing the light component removal product with a crystallization solvent to carry out crystallization and solid-liquid separation to obtain a crystalline crystal; and
(5) subjecting the crystalline crystal to a hydrogenation reaction;
wherein the crystallization solvent contains 0.1-2 wt % of ethanol.