Preparation method of epsilon-caprolactam
A technology of caprolactam and cyclohexanone oxime, which is applied in the field of purification and preparation of ε-caprolactam, can solve the problem that crude ε-caprolactam cannot be processed economically for a long time, and achieve the effects of small load, extended life and high product yield
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Embodiment 1
[0074] In a fluidized bed reactor equipped with a high silica content zeolite catalyst, a mixed liquid of cyclohexanone oxime, methanol and water (weight ratio is 1:1.8:0.052) is introduced together with the nitrogen passing through the evaporator. The Beckmann rearrangement was carried out at a reaction temperature of ℃, and the residence time was 8sec. The reaction gas is cooled and condensed to obtain a reaction mixture containing ε-caprolactam.
[0075] The reaction mixture was distilled to remove methanol, low-boiling impurities and high-boiling impurities to obtain crude ε-caprolactam with a purity of 98.97%. According to gas chromatography analysis, the content of cyclohexanone oxime was 584 ppm, the content of MTHI was 604 ppm, and the content of OHP was The content is 355ppm.
[0076]In a 200L reactor, add the crude ε-caprolactam (31.28kg) obtained after rectification and the mixed solvent of cyclohexane and n-heptane (weight ratio 1:3) (46.92kg), and heat to 70℃ The ε-ca...
Embodiment 2
[0081] The cyclohexanone oxime was subjected to Beckmann rearrangement, and the obtained crude ε-caprolactam was distilled in the same manner as in Example 1. The purity of the obtained crude ε-caprolactam was 99.20%. According to gas chromatography analysis, it contained 1736 ppm of cyclohexane. Ketone oxime, 300 ppm MTHI and 248 ppm OHP.
[0082] The obtained crude ε-caprolactam (50 g) was dissolved in a mixed solvent of cyclohexane and n-heptane (weight ratio 1:3) (75 g), and the resulting solution was cooled while stirring to crystallize ε-caprolactam. The crystalline ε-caprolactam was collected by a centrifugal separator, and the collected crystal ε-caprolactam was washed with the cyclohexane and n-heptane mixed solvent (25 g) used above to obtain ε-caprolactam crystals (46.32 g). The yield was 92.63%. The crystalline ε-caprolactam was analyzed as described above. As a result, the contents of cyclohexanone oxime, MTHI and OHP were all lower than the detection limit, the conte...
Embodiment 3
[0086] The cyclohexanone oxime was subjected to Beckmann rearrangement, and the crude ε-caprolactam was distilled in the same manner as in Example 1. The purity of the obtained crude ε-caprolactam was 99.08%. According to gas chromatography analysis, it contained 188 ppm of cyclohexanone oxime, 469ppm MTHI and 205ppm OHP.
[0087] The heptane (82.5 g) was heated into the distilled ε-caprolactam (55 g) and the resulting solution was kept at 70°C. Additional heptane (82.5 g) was cooled with ice.
[0088] Then, a mixture of ε-caprolactam and heptane maintained at 70°C and ice-cooled heptane were simultaneously added dropwise within 10 minutes into a flask maintained at 58°C to precipitate ε-caprolactam. After 30 minutes, the precipitated ε-caprolactam crystals were collected with a centrifugal collector, and the collected ε-caprolactam was washed with heptane (27.5g) to obtain ε-caprolactam crystals (34.76g). The yield was 63.2%. The obtained crystal ε-caprolactam was analyzed as des...
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