Method for preparing valerolactam through cyclopentanone oxime crude liquid refining purification and gas phase rearrangement

The invention discloses a method for preparing valerolactam by refining, purifying and gas-phase rearrangement of crude cyclopentanone oxime, which comprises the following steps of: extracting the crude cyclopentanone oxime by using methylcyclohexane at the temperature of between 40 and 80 DEG C, cooling the extracted organic phase, separating out cyclopentanone oxime solid, and carrying out Beckmann rearrangement reaction on the cyclopentanone oxime solid to obtain the valerolactam. Valerolactam is obtained. Compared with the prior art, the method has the advantages that the process is simplified, the energy consumption is reduced, the quality of the valerolactam product is improved by improving the purity of the intermediate cyclopentanone oxime, the industrial production of the valerolactam is realized by catalyzing the Beckmann gas phase rearrangement reaction through the molecular sieve, the use of fuming sulfuric acid or concentrated sulfuric acid as a catalyst is avoided, and the energy conservation an