Method for purifying and refining epsi-caprolactam
A technology of caprolactam and refining method, which is applied in the field of purification and refining of ε-caprolactam, and can solve the problems of reduced reaction efficiency and lower absorption value of potassium permanganate
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Embodiment 1
[0035] The gas-phase Beckmann rearrangement reaction of cyclohexanone oxime was carried out in an 80ml fixed-bed reaction device. The inner diameter of the reactor was 28mm, and the molecular sieve catalyst with a high silicon-aluminum ratio MFI structure was loaded with 9.45g (Φ1.8mm strip catalyst). Pressure 0.1MPa, catalyst bed reaction temperature 365°C-385°C, carrier gas flow rate 3.0L / gcat / hr, cyclohexanone oxime WHSV 2h -1 , The partial pressure range of the mixed material: cyclohexanone oxime 5.5kPa-11.6kPa, methanol (solvent) 36.9kPa-70.6kPa, nitrogen (carrier gas) 19.4kPa-52.6kPa. The reaction product was collected by circulating and cooling the ethylene glycol solution at -5°C to obtain a reaction product containing ε-caprolactam.
[0036] First, the reaction mixture is distilled by simple distillation to remove methanol, low-boiling impurities and high-boiling impurities, and finally obtain crude ε-caprolactam. On the 6890 type gas chromatograph of Agilent Company...
Embodiment 2
[0040] As described in Example 1, take 2.0Kg of the crude ε-caprolactam obtained by the above simple distillation method, put it into a 10L reactor, add 2.0Kg of isopropyl ether, heat to 60-70°C, and stir for 30 minutes to make ε-caprolactam Caprolactam is completely dissolved in this solvent. Continue cooling while stirring, the temperature is cooled from 70°C to about 15°C, and ε-caprolactam crystals are completely precipitated. After centrifugation, 1.94Kg99.92%ε-caprolactam crystals and 2.05Kg95.8%ether were obtained. Ether solvent is recovered. 1.94Kg ε-caprolactam crystals were returned to the 10L reactor, 1.94Kg n-heptane was added, stirred and washed at room temperature for 30 minutes, and then centrifuged to obtain 99.95% ε-caprolactam crystals and 98.8% n-heptane (otherwise included 1.00% ε-caprolactam). n-heptane solvent for recovery. The obtained ε-caprolactam has a PM value of 126s and an E value of <0.6.
[0041] Hydrogenation reaction: Take 99.95% ε-caprola...
Embodiment 3
[0043] As described in Example 1, the ε-caprolactam crystals obtained by using isopropyl ether as the crystallization solvent and washing solvent were subjected to hydrogenation reaction, and the hydrogenation reaction was as follows.
[0044] Hydrogenation reaction: take 99.96% ε-caprolactam crystals washed once with 2.1Kg isopropyl ether, add them to a 5L reaction kettle, add 210g SRNA-4 industrial grade amorphous nickel hydrogenation catalyst, heat to about 90°C, Pass in hydrogen, the flow rate of hydrogen is controlled at 0.6 L / min, the reaction pressure is maintained at 5 atm, the ε-caprolactam in molten state is contacted with hydrogen, and reacted for 1 hour. Afterwards, the reaction product was distilled under reduced pressure at about 1 mmHg to obtain 2.06 Kg ε-caprolactam with a yield of 98%. The quality of the obtained ε-caprolactam product was analyzed, the PM value was 32000s, and the E value was <0.05.
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