Preparation method for caprolactam

The invention provides a preparation method of caprolactam, which includes the following steps: (1) in the presence of an oximation catalyst without any organic solvent, cyclohexanone, ammonia and hydrogen peroxide are subjected to an ammoximation reaction in a water solution at 50-200 DEG C to prepare a solution containing cyclohexanone-oxime; (2) extracting the solution containing cyclohexanone-oxime with an inert organic solution to obtain an extract phase containing the cyclohexanone-oxime and a raffinate phase containing the oximation catalyst and water; (3) performing a Beckmann rearrangement reaction to the extract phase and fuming sulfuric acid, and performing a neutralization reaction to the product of the Beckmann rearrangement reaction with ammonia. The method can not only increase the yield of caprolactam but also omits a purifying process of cyclohexanone-oxime, thereby significantly reducing the process and production period. Meanwhile, the inert organic solvent can be recycled by recycling rear