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Caprolactam continuous crystallization purification method

A technology of caprolactam and purification method, which is applied in the field of caprolactam, can solve the problems of affecting the quality of caprolactam, low washing efficiency, cumbersome process, etc., and achieve the effect of excellent and stable product quality, high washing efficiency and simple process

Inactive Publication Date: 2020-05-19
FUJIAN ZHONGJIN NEW MATERIALS
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The caprolactam prepared by these methods inevitably contains a large number of organic impurities, which seriously affect the quality of caprolactam, therefore, must be purified before application
[0003] Practical industrial applications are faced with the problems of solid-liquid separation of crystals and mother liquor as well as crystal washing and filtration. Using existing solid-liquid separation methods such as centrifugal filtration, pressure filtration, and vacuum filtration, not only the process is cumbersome, the investment is large, and the washing efficiency is low.

Method used

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  • Caprolactam continuous crystallization purification method
  • Caprolactam continuous crystallization purification method

Examples

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Effect test

Embodiment 1

[0023] A method for continuous crystallization and purification of caprolactam, comprising the steps of:

[0024] S1. Send the caprolactam crude liquid into the distillation tower, conduct vacuum distillation at 115°C, and the vacuum distillation pressure is 0.15 MPa, obtain gas phase caprolactam at the top of the distillation tower, and condense through a condenser to obtain liquid caprolactam;

[0025] S2. Add 800 kg of deionized water to 100 kg of liquid caprolactam, adjust the temperature to 60° C. and stir for 10 minutes, keep warm for 30 minutes, then cool down to 4° C. at a rate of 1° C. / min, keep warm for 1 hour, centrifuge, and dry to obtain caprolactam grains;

[0026] S3. Add 100kg caprolactam grains to 2000kg deionized water, then raise the temperature from room temperature to 65°C under stirring, then stir for 15 minutes, then cool down to 48°C, keep warm for 40 minutes, and then cool down to 40°C at a speed of 0.2°C / min. °C, keep warm for 1 h, centrifuge, and dry...

Embodiment 2

[0028] A method for continuous crystallization and purification of caprolactam, comprising the steps of:

[0029] S1. Send the caprolactam crude liquid into the distillation tower, distill under reduced pressure at 120°C, the pressure of the vacuum distillation is 0.1MPa, obtain gas-phase caprolactam at the top of the distillation tower, and condense through a condenser to obtain liquid caprolactam;

[0030] S2. Add 1200 kg of deionized water to 100 kg of liquid caprolactam, adjust the temperature to 50° C. and stir for 20 minutes, keep warm for 10 minutes, then cool down to 2° C. at a rate of 2° C. / min, keep warm for 2 hours, centrifuge, and dry to obtain caprolactam grains;

[0031] S3. Add 100kg caprolactam crystal grains to 1500kg deionized water, then raise the temperature from room temperature to 75°C under stirring, stir for 5 minutes, then cool down to 52°C, keep warm for 20min, and then cool down to 20°C at a speed of 0.6°C / min. °C, keep warm for 2 hours, centrifuge a...

Embodiment 3

[0033] A method for continuous crystallization and purification of caprolactam, comprising the steps of:

[0034] S1. Send the caprolactam crude liquid into the distillation tower, conduct vacuum distillation at 116°C, and the vacuum distillation pressure is 0.13 MPa, obtain gas phase caprolactam at the top of the distillation tower, and condense through a condenser to obtain liquid caprolactam;

[0035] S2. Add 4,500 kg of deionized water to 500 kg of liquid caprolactam, adjust the temperature to 58° C. and stir for 13 minutes, keep warm for 25 minutes, then cool down to 3.5° C. at a rate of 1.2° C. / min, keep warm for 1.3 hours, centrifuge, and dry to obtain caprolactam grains;

[0036] S3. Add 500kg of caprolactam grains to 9000kg of deionized water, then raise the temperature from room temperature to 68°C under stirring, then stir for 12 minutes, then cool down to 49°C, keep warm for 35 minutes, and then cool down to 3.5°C at a rate of 0.3°C / min. °C, keep warm for 1.3h, cen...

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Abstract

The invention discloses a caprolactam continuous crystallizationpurification method which comprises the following steps: feeding a caprolactam crude liquid into a distillation tower, carrying out reduced pressure distillation to obtain gas-phase caprolactam at the top of the distillation tower, and condensing the gas-phase caprolactam through a condenser to obtain liquid caprolactam;adding deionized water into the liquid caprolactam, adjusting the temperature to 50-60 DEG C, stirring for 10-20 minutes, keeping the temperature for 10-30 minutes, cooling to 2-4 DEG C, keeping the temperature for1-2 hours, centrifuging, and drying to obtain caprolactam crystal grains; adding the caprolactam crystal grains into deionized water, heating to 65-75 DEG C from room temperature in a stirring state,stirring for 5-15 minutes, cooling to 48-52 DEG C, keeping the temperature for 20-40 minutes, cooling to 2-4 DEG C, keeping the temperature for 1-2 hours, centrifuging, and drying to obtain purifiedcaprolactam. The method has the advantages of simple process, low investment and high washing efficiency, and can effectively enhance the superior product rate of the caprolactam finished product.

Description

technical field [0001] The invention relates to the technical field of caprolactam, in particular to a method for continuous crystallization and purification of caprolactam. Background technique [0002] Caprolactam is an important monomer of synthetic fibers and synthetic resins, mainly used in the manufacture of polyamide fibers, resins and films, etc. Known caprolactam production methods include cyclohexanone oxime liquid-phase Beckmann rearrangement method using oleum as a catalyst , Gas-phase Beckmann rearrangement of cyclohexanone oxime using solid zeolite as a catalyst, and depolymerization of waste polymers. The caprolactam prepared by these methods inevitably contains a large variety of organic impurities, which seriously affect the quality of caprolactam, and therefore must be purified before application. [0003] Practical industrial applications are faced with the problems of solid-liquid separation of crystals and mother liquor and crystal washing and filtratio...

Claims

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Application Information

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IPC IPC(8): C07D201/16C07D223/10
CPCC07D201/16C07D223/10C07B2200/13
Inventor 潘永超张良铖
Owner FUJIAN ZHONGJIN NEW MATERIALS