CN107235901B - Process for removing alkaline impurities in caprolactam refining process - Google Patents
Process for removing alkaline impurities in caprolactam refining process Download PDFInfo
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- CN107235901B CN107235901B CN201610187661.9A CN201610187661A CN107235901B CN 107235901 B CN107235901 B CN 107235901B CN 201610187661 A CN201610187661 A CN 201610187661A CN 107235901 B CN107235901 B CN 107235901B
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- caprolactam
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- containing gas
- potassium permanganate
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07D—HETEROCYCLIC COMPOUNDS
- C07D223/00—Heterocyclic compounds containing seven-membered rings having one nitrogen atom as the only ring hetero atom
- C07D223/02—Heterocyclic compounds containing seven-membered rings having one nitrogen atom as the only ring hetero atom not condensed with other rings
- C07D223/06—Heterocyclic compounds containing seven-membered rings having one nitrogen atom as the only ring hetero atom not condensed with other rings with hetero atoms or with carbon atoms having three bonds to hetero atoms with at the most one bond to halogen, e.g. ester or nitrile radicals, directly attached to ring carbon atoms
- C07D223/08—Oxygen atoms
- C07D223/10—Oxygen atoms attached in position 2
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07D—HETEROCYCLIC COMPOUNDS
- C07D201/00—Preparation, separation, purification or stabilisation of unsubstituted lactams
- C07D201/16—Separation or purification
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- Other In-Based Heterocyclic Compounds (AREA)
Abstract
The invention discloses a process for removing alkaline impurities in a caprolactam refining process, wherein the caprolactam refining process comprises the working procedures of extraction, ion exchange, hydrogenation, evaporation and distillation, and oxygen-containing gas is introduced into a caprolactam solution and/or an acidic potassium permanganate solution is added into the caprolactam solution during or after the evaporation working procedure, and the caprolactam solution is heated for oxidation treatment; or introducing high-temperature oxygen-containing gas and/or adding high-temperature acidic potassium permanganate solution into the caprolactam solution for oxidation treatment; can effectively reduce alkaline impurities in caprolactam products, does not affect other indexes, has simple operation and low cost, and meets the requirement of industrial production.
Description
Technical Field
The invention relates to a process for removing alkaline impurities in a caprolactam refining process, in particular to a process for removing alkaline impurities generated in a caprolactam impurity hydrogenation process, and belongs to the technical field of caprolactam production.
Background
Caprolactam produced by the ammoximation process contains a large variety of impurities, which are mainly organic impurities. There are three main sources for impurities: 1. the conversion of raw materials is incomplete, such as cyclohexanone and cyclohexanone oxime in products, 2, byproducts generated in the reaction process, such as beta-hydroxycyclohexanone, adipimide, n-caproamide and the like, 3, impurities carried in the raw materials are converted into new impurities in the reaction, such as hexanal which is converted into hexylamine through ammoximation and Beckmann rearrangement reaction. The traditional caprolactam refining process mainly comprises the processes of extraction, ion exchange, hydrogenation, evaporation, distillation and the like, and the refined product can reach a high-grade product, but the content of alkaline impurities in the product is unstable, so that the high-grade product rate of the product is low.
The basic impurities in the refined caprolactam product are mainly derived from two sources: firstly, cyclohexanone oxime and nicotinic acid are subjected to Beckmann rearrangement to obtain byproducts, and secondly, alkaline impurities in materials are doubled and increased after hydrogenation reaction in the refining process. In the existing caprolactam refining process, the control of basic impurities mainly depends on the adsorption and interception action of ion exchange resin, but the ion exchange resin has limited treatment capacity and higher cost, and particularly for the basic impurities generated after the ion exchange process, the basic impurities cannot be removed in the subsequent evaporation and distillation processes because the melting point and the boiling point are very close to those of caprolactam.
Disclosure of Invention
Aiming at the problems of the existing caprolactam refining process, the invention aims to provide a process which can effectively reduce alkaline impurities in a caprolactam product without influencing other indexes, is simple to operate and low in cost, and meets the requirements of industrial production.
In order to achieve the technical purpose, the invention provides a process for removing alkaline impurities in a caprolactam refining process, wherein the caprolactam refining process comprises the working procedures of extraction, ion exchange, hydrogenation, evaporation and distillation, oxygen-containing gas and/or acidic potassium permanganate solution is introduced into caprolactam solution in or after the evaporation working procedure, and the caprolactam solution is heated to 120-130 ℃ for oxidation treatment; or introducing oxygen-containing gas at the temperature of 80-130 ℃ into the caprolactam solution and/or adding an acidic potassium permanganate solution at the temperature of 80-130 ℃ for oxidation treatment.
Preferably, the oxidation treatment time is not longer than 90 seconds.
Preferably, the oxygen-containing gas is air and/or oxygen.
In a preferred embodiment, the ratio of the amount of oxygen-containing gas introduced to the flow rate of caprolactam solution is not more than 2.2Nm3:1m3。
In the preferred scheme, the concentration of the acidic potassium permanganate solution is 0.5 percent by mass.
In a more preferable scheme, the volume ratio of the addition amount of the acidic potassium permanganate solution to the addition amount of the caprolactam solution is less than 0.02.
In a preferable scheme, the caprolactam solution after the hydrogenation procedure is filtered and separated to remove the hydrogenation catalyst.
In the technical scheme of the invention, alkaline impurities in caprolactam can be selectively oxidized by oxygen-containing gas or acidic potassium permanganate solution, the oxidation reaction is mainly oxygenation oxidation, the molecular weight of the product generated after oxidation is increased, the boiling point is changed, the product is favorably separated and removed in the subsequent evaporation and distillation processes, the impurities in caprolactam products are reduced, and the alkalinity qualification rate is obviously improved.
In a preferred scheme, the oxygen-containing gas and/or the acid potassium permanganate solution adding point can be in a three-effect evaporation first tower, a three-effect evaporation second tower, a three-effect evaporation third tower or a flash heater.
The technical scheme of the invention has the following beneficial effects:
1. after the treatment of the technical scheme of the invention, the alkalinity of alkaline impurities in caprolactam is reduced by about 45 percent, and the alkalinity qualification rate is obviously improved;
2. the load and the using amount of the ion exchange resin can be reduced, the service cycle of the ion exchange resin is prolonged, the regeneration cost of the ion exchange resin is reduced by more than 70%, the discharge amount of wastewater is reduced by 56%, and the production cost is reduced;
3. the oxidation treatment process is simple, has low cost and meets the requirement of industrial production.
Detailed Description
The following examples are intended to further illustrate the present disclosure, but not to limit the scope of the claims.
Example 1
And (2) hydrogenating a caprolactam water solution with the concentration of 28-38% and the temperature of 80-90 ℃, removing a hydrogenation catalyst in water solution, and then sending the caprolactam water solution into a three-effect evaporation tower for concentration. The kettle temperature of the first triple effect evaporation tower is controlled to be 120-130 ℃, the temperature of the second tower is controlled to be 105-115 ℃, the kettle temperature of the third tower is controlled to be 72-78 ℃, the concentration of the material evaporated from the triple effect evaporation tower is 90%, and concentrated solution is obtainedThe temperature of the materials is raised to 125 ℃ by a row of tubular heaters, pure normal temperature air is introduced at the inlets of the heaters, and the air flow and the material flow are kept at 1m3:1Nm3. The material after air oxidation enters a flash separation tank to separate most of water, the concentration of caprolactam reaches over 99.7 percent, and the alkalinity of the caprolactam is about 0.3 mg/kg. Compared with the original process without oxidation treatment, the degree is reduced by 40 percent.
Example 2
The difference between this example and example 1 is that pure air is added from the bottom of the triple effect evaporation tower-tower, the other control conditions and flow are not changed, and the obtained concentrated caprolactam with the concentration of 99.7% has the alkalinity of 0.52mg/kg, which is reduced by about 20% compared with the original process.
Example 3
The difference between this example and example 1 is that pure air is added from the second tower still of the triple effect evaporation tower, the other control conditions and flow are not changed, and the alkalinity of the obtained concentrated caprolactam with the concentration of 99.7% is 0.56mg/kg, which is reduced by about 10% compared with the original process.
Example 4
The difference between the example and the example 1 is that pure air is added from the three-tower kettle of the triple-effect evaporation tower, the other control conditions and the flow are not changed, the obtained concentrated caprolactam with the concentration of 99.7 percent has the alkalinity of 0.58mg/kg, and is reduced by about 5 percent compared with the original process.
Example 5
The difference between this example and example 1 is that pure air is added from the middle of the heater, the rest of control and flow are not changed, and the obtained concentrated caprolactam with the concentration of 99.7% has the alkalinity of 0.35mg/kg, which is reduced by about 38% compared with the original process.
Example 6
The difference between this example and example 1 is that air is heated by a heater from normal temperature to 74 ℃, then the air is added from the inlet of the material heater, other control conditions and flow are not changed, concentrated caprolactam with the concentration of 99.7% is obtained, the measured alkalinity is 0.31mg/kg, which is reduced by about 39% compared with the original process.
Example 7
The difference between this example and example 1 is that a heater is used to heat air from normal temperature to 130 deg.C, then the air is added from the inlet of the material heater, other control conditions and flow are not changed, concentrated caprolactam with 99.7% concentration is obtained, the measured alkalinity is 0.36mg/kg, which is reduced by about 35% compared with the original process.
Example 8
The difference between this example and example 1 is that 0.5% acidic potassium permanganate solution is used to replace pure air as oxidant, then the oxidant is added from the inlet of the material heater, other control conditions and flow are not changed, and the alkalinity of the obtained concentrated caprolactam with the concentration of 99.7% is measured to be 0.37mg/kg, which is reduced by about 35% compared with the original process.
Claims (2)
1. A process for removing alkaline impurities in a caprolactam refining process, wherein the caprolactam refining process comprises the working procedures of extraction, ion exchange, hydrogenation, evaporation and distillation, and is characterized in that: introducing oxygen-containing gas and/or adding an acidic potassium permanganate solution into the caprolactam solution in or after the evaporation process, and heating to 120-130 ℃ for oxidation treatment; or introducing oxygen-containing gas at the temperature of 80-130 ℃ into the caprolactam solution and/or adding an acidic potassium permanganate solution at the temperature of 80-130 ℃ for oxidation treatment;
the time of the oxidation treatment is not longer than 90 seconds;
the ratio of the amount of oxygen-containing gas introduced to the flow rate of caprolactam solution is not higher than 2.2Nm3:1m3；
The concentration of the acidic potassium permanganate solution is 0.5 percent by mass;
the volume ratio of the addition amount of the acidic potassium permanganate solution to the caprolactam solution is less than 0.02.
2. The process according to claim 1, for removing alkaline impurities during the refining of caprolactam, characterized in that: the oxygen-containing gas is air and/or oxygen.
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| CN109694349B (en) * | 2017-10-24 | 2022-10-14 | 中国石油化工股份有限公司 | Caprolactam refining method |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101767860A (en) * | 2010-01-28 | 2010-07-07 | 河北瑞通美邦工程有限公司 | Recovery process of caprolactam refining raffinate |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN101767860A (en) * | 2010-01-28 | 2010-07-07 | 河北瑞通美邦工程有限公司 | Recovery process of caprolactam refining raffinate |
Non-Patent Citations (3)
| Title |
|---|
| 己内酰胺杂质形成及其精制;谭永泰等;《石油化工》;19760131(第1期);96页左栏第2段 * |
| 浅谈己内酰胺产品中的杂质;罗晓强等;《化工时刊》;20120726;第26卷(第7期);第40页3.3 * |
| 环己酮肟气相贝克曼重排反应产物己内酰胺的精制研究;谢丽等;《石油炼制与化工》;20150512;第46卷(第5期);第7页1.2、第11页3 * |
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