Abstract: A method is provided for evaporating cyclohexanone oxime in which cyclohexanone oxime is evaporated using a falling-film evaporator with wetting the evaporation surface of the evaporator well with the cyclohexanone oxime at a pressure of less than about 1060 Torr with a falling rate of the cyclohexanone oxime of about 170 kg/hour or more per one meter around the circumference of evaporation surface at the lowest part of the evaporator. In this method, the cyclohexanone oxime is evaporated efficiently with little decomposition thereof, while preventing the plugging of the pipes of the evaporator and continuously carrying out the operation of the evaporator for a long period of time.

Abstract: A method is provided for evaporating cyclohexanone oxime in which cyclohexanone oxime is evaporated using a falling-film evaporator with wetting the evaporation surface of the evaporator well with the cyclohexanone oxime at a pressure of less than about 1060 Torr with a falling rate of the cyclohexanone oxime of about 170 kg/hour or more per one meter around the circumference of evaporation surface at the lowest part of the evaporator. In this method, the cyclohexanone oxime is evaporated efficiently with little decomposition thereof, while preventing the plugging of the pipes of the evaporator and continuously carrying out the operation of the evaporator for a long period of time.

Abstract: A high purity &egr;-caprolactam is prepared by pouring a molten crude &egr;-caprolactam and a solvent comprising an aliphatic hydrocarbon and having a lower temperature than that of the crude &egr;-caprolactam, into a vessel and mixing them to obtain a first slurry containing a crystallized &egr;-caprolactam. The slurry is then subjected to a solid-liquid separation to obtain &egr;-caprolactam and a first liquid phase. This process can effectively remove impurities from a crude &egr;-caprolactam, which is obtained by for example, subjecting cyclohexanone oxime to the Beckmann rearrangement.

Abstract: A high purity &egr;-caprolactam is prepared by pouring a molten crude &egr;-caprolactam and a solvent comprising an aliphatic hydrocarbon and having a lower temperature than that of the crude &egr;-caprolactam, into a vessel and mixing them to obtain a first slurry containing a crystallized &egr;-caprolactam. The slurry is then subjected to a solid-liquid separation to obtain &egr;-caprolactam and a first liquid phase. This process can effectively remove impurities from a crude &egr;-caprolactam, which is obtained by for example, subjecting cyclohexanone oxime to the Beckmann rearrangement.

Abstract: A process for producing &egr;-caprolactam is provided which comprises the steps of subjecting cyclohexanone oxime to a gaseous phase Beckmann rearrangement reaction in a fluidized bed system using a solid catalyst and re-generating the catalyst, wherein said process comprises a step of treating the catalyst with an oxygen-containing gas at an elevated temperature in a re-generation step so that the nitrogen content of the catalyst falls within a range of 10 ppm to 2,500 ppm on its way to the reaction step from the re-generating step. According to the present invention, &egr;-caprolactam is produced with a high conversion or a high selectivity without interrupting the rearrangement reaction or the re-generation step.

Abstract: An apparatus for the production of &egr;-caprolactam is provided which comprises (i) a fluidized bed reactor having a solid catalyst therein for subjecting cyclohexanone oxime to a rearrangement reaction to obtain a reaction product containing unreacted cyclohexanone oxime and (ii) a fixed bed reactor packed with a solid catalyst for subjecting the unreacted cyclohexanone oxime to a rearrangement reaction to obtain &egr;-caprolactam. Using the apparatus, &egr;-caprolactam is obtained with a high yield.