CN115093354A - Method for synthesizing caprolactam through Beckmann rearrangement reaction - Google Patents
Method for synthesizing caprolactam through Beckmann rearrangement reaction Download PDFInfo
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- JBKVHLHDHHXQEQ-UHFFFAOYSA-N epsilon-caprolactam Chemical compound O=C1CCCCCN1 JBKVHLHDHHXQEQ-UHFFFAOYSA-N 0.000 title claims abstract description 204
- 238000000034 method Methods 0.000 title claims abstract description 29
- 238000006237 Beckmann rearrangement reaction Methods 0.000 title claims abstract description 21
- 230000002194 synthesizing effect Effects 0.000 title claims abstract description 16
- VEZUQRBDRNJBJY-UHFFFAOYSA-N cyclohexanone oxime Chemical compound ON=C1CCCCC1 VEZUQRBDRNJBJY-UHFFFAOYSA-N 0.000 claims abstract description 92
- BFNBIHQBYMNNAN-UHFFFAOYSA-N ammonium sulfate Chemical compound N.N.OS(O)(=O)=O BFNBIHQBYMNNAN-UHFFFAOYSA-N 0.000 claims abstract description 51
- 239000002904 solvent Substances 0.000 claims abstract description 47
- 229910052921 ammonium sulfate Inorganic materials 0.000 claims abstract description 44
- 235000011130 ammonium sulphate Nutrition 0.000 claims abstract description 44
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims abstract description 43
- 238000006243 chemical reaction Methods 0.000 claims abstract description 40
- HIFJUMGIHIZEPX-UHFFFAOYSA-N sulfuric acid;sulfur trioxide Chemical compound O=S(=O)=O.OS(O)(=O)=O HIFJUMGIHIZEPX-UHFFFAOYSA-N 0.000 claims abstract description 22
- 230000008569 process Effects 0.000 claims abstract description 17
- 239000000243 solution Substances 0.000 claims description 82
- UHOVQNZJYSORNB-UHFFFAOYSA-N Benzene Chemical compound C1=CC=CC=C1 UHOVQNZJYSORNB-UHFFFAOYSA-N 0.000 claims description 48
- 238000003756 stirring Methods 0.000 claims description 37
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 25
- IJQAOQPOJZUGIA-UHFFFAOYSA-N azepan-2-one benzene Chemical compound c1ccccc1.O=C1CCCCCN1 IJQAOQPOJZUGIA-UHFFFAOYSA-N 0.000 claims description 23
- WEVYAHXRMPXWCK-UHFFFAOYSA-N Acetonitrile Chemical compound CC#N WEVYAHXRMPXWCK-UHFFFAOYSA-N 0.000 claims description 15
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 claims description 14
- 239000007788 liquid Substances 0.000 claims description 14
- AWSFEOSAIZJXLG-UHFFFAOYSA-N azepan-2-one;hydrate Chemical compound O.O=C1CCCCCN1 AWSFEOSAIZJXLG-UHFFFAOYSA-N 0.000 claims description 13
- DKGAVHZHDRPRBM-UHFFFAOYSA-N Tert-Butanol Chemical compound CC(C)(C)O DKGAVHZHDRPRBM-UHFFFAOYSA-N 0.000 claims description 11
- 238000001704 evaporation Methods 0.000 claims description 11
- 230000008020 evaporation Effects 0.000 claims description 11
- QPFMBZIOSGYJDE-UHFFFAOYSA-N 1,1,2,2-tetrachloroethane Chemical compound ClC(Cl)C(Cl)Cl QPFMBZIOSGYJDE-UHFFFAOYSA-N 0.000 claims description 10
- ZWEHNKRNPOVVGH-UHFFFAOYSA-N 2-Butanone Chemical compound CCC(C)=O ZWEHNKRNPOVVGH-UHFFFAOYSA-N 0.000 claims description 10
- 239000007864 aqueous solution Substances 0.000 claims description 10
- 238000006386 neutralization reaction Methods 0.000 claims description 10
- RYHBNJHYFVUHQT-UHFFFAOYSA-N 1,4-Dioxane Chemical compound C1COCCO1 RYHBNJHYFVUHQT-UHFFFAOYSA-N 0.000 claims description 5
- CSCPPACGZOOCGX-UHFFFAOYSA-N Acetone Chemical compound CC(C)=O CSCPPACGZOOCGX-UHFFFAOYSA-N 0.000 claims description 4
- 238000002425 crystallisation Methods 0.000 claims description 4
- 230000008025 crystallization Effects 0.000 claims description 4
- 239000011259 mixed solution Substances 0.000 claims description 4
- ZMXDDKWLCZADIW-UHFFFAOYSA-N N,N-Dimethylformamide Chemical compound CN(C)C=O ZMXDDKWLCZADIW-UHFFFAOYSA-N 0.000 claims description 2
- 230000007935 neutral effect Effects 0.000 claims description 2
- 230000035484 reaction time Effects 0.000 claims description 2
- 238000005185 salting out Methods 0.000 claims description 2
- 239000006227 byproduct Substances 0.000 abstract description 26
- 239000003054 catalyst Substances 0.000 abstract description 7
- 238000009776 industrial production Methods 0.000 abstract description 4
- 239000002994 raw material Substances 0.000 abstract description 4
- 239000000376 reactant Substances 0.000 abstract description 4
- 238000001556 precipitation Methods 0.000 abstract 1
- 239000012071 phase Substances 0.000 description 64
- 238000000605 extraction Methods 0.000 description 26
- PVNIIMVLHYAWGP-UHFFFAOYSA-N Niacin Chemical compound OC(=O)C1=CC=CN=C1 PVNIIMVLHYAWGP-UHFFFAOYSA-N 0.000 description 10
- 238000004458 analytical method Methods 0.000 description 9
- 229920006395 saturated elastomer Polymers 0.000 description 9
- 239000008346 aqueous phase Substances 0.000 description 8
- YXFVVABEGXRONW-UHFFFAOYSA-N Toluene Chemical compound CC1=CC=CC=C1 YXFVVABEGXRONW-UHFFFAOYSA-N 0.000 description 6
- 230000000052 comparative effect Effects 0.000 description 5
- 239000011664 nicotinic acid Substances 0.000 description 5
- 229960003512 nicotinic acid Drugs 0.000 description 5
- 235000001968 nicotinic acid Nutrition 0.000 description 5
- XSTXAVWGXDQKEL-UHFFFAOYSA-N Trichloroethylene Chemical group ClC=C(Cl)Cl XSTXAVWGXDQKEL-UHFFFAOYSA-N 0.000 description 4
- 239000000047 product Substances 0.000 description 4
- UBOXGVDOUJQMTN-UHFFFAOYSA-N trichloroethylene Natural products ClCC(Cl)Cl UBOXGVDOUJQMTN-UHFFFAOYSA-N 0.000 description 4
- SKDFWEPBABSFMG-UHFFFAOYSA-N 1,2-dichloro-1,1-difluoroethane Chemical compound FC(F)(Cl)CCl SKDFWEPBABSFMG-UHFFFAOYSA-N 0.000 description 3
- 229920002292 Nylon 6 Polymers 0.000 description 3
- HIGZEFHDFAMPND-UHFFFAOYSA-N azepan-2-one;sulfuric acid Chemical compound OS(O)(=O)=O.O=C1CCCCCN1 HIGZEFHDFAMPND-UHFFFAOYSA-N 0.000 description 3
- 238000004519 manufacturing process Methods 0.000 description 3
- 230000008707 rearrangement Effects 0.000 description 3
- ISWSIDIOOBJBQZ-UHFFFAOYSA-N Phenol Chemical compound OC1=CC=CC=C1 ISWSIDIOOBJBQZ-UHFFFAOYSA-N 0.000 description 2
- 239000002253 acid Substances 0.000 description 2
- 238000012870 ammonium sulfate precipitation Methods 0.000 description 2
- JHIVVAPYMSGYDF-UHFFFAOYSA-N cyclohexanone Chemical compound O=C1CCCCC1 JHIVVAPYMSGYDF-UHFFFAOYSA-N 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 238000005507 spraying Methods 0.000 description 2
- 229910021653 sulphate ion Inorganic materials 0.000 description 2
- 229920000742 Cotton Polymers 0.000 description 1
- 239000004677 Nylon Substances 0.000 description 1
- 230000002378 acidificating effect Effects 0.000 description 1
- 150000001408 amides Chemical class 0.000 description 1
- 230000000702 anti-platelet effect Effects 0.000 description 1
- 239000003146 anticoagulant agent Substances 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000006555 catalytic reaction Methods 0.000 description 1
- 239000013064 chemical raw material Substances 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 239000003814 drug Substances 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 239000003337 fertilizer Substances 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 239000002608 ionic liquid Substances 0.000 description 1
- 239000002649 leather substitute Substances 0.000 description 1
- 150000007522 mineralic acids Chemical class 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000002808 molecular sieve Substances 0.000 description 1
- 239000000178 monomer Substances 0.000 description 1
- 229920001778 nylon Polymers 0.000 description 1
- 150000007524 organic acids Chemical class 0.000 description 1
- 235000005985 organic acids Nutrition 0.000 description 1
- 150000002923 oximes Chemical class 0.000 description 1
- 238000004806 packaging method and process Methods 0.000 description 1
- 239000004033 plastic Substances 0.000 description 1
- 229920003023 plastic Polymers 0.000 description 1
- 229920000642 polymer Polymers 0.000 description 1
- 238000006116 polymerization reaction Methods 0.000 description 1
- 230000001376 precipitating effect Effects 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 230000036632 reaction speed Effects 0.000 description 1
- 238000006462 rearrangement reaction Methods 0.000 description 1
- URGAHOPLAPQHLN-UHFFFAOYSA-N sodium aluminosilicate Chemical compound [Na+].[Al+3].[O-][Si]([O-])=O.[O-][Si]([O-])=O URGAHOPLAPQHLN-UHFFFAOYSA-N 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 238000003786 synthesis reaction Methods 0.000 description 1
- 239000004753 textile Substances 0.000 description 1
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Classifications
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07D—HETEROCYCLIC COMPOUNDS
- C07D201/00—Preparation, separation, purification or stabilisation of unsubstituted lactams
- C07D201/02—Preparation of lactams
- C07D201/04—Preparation of lactams from or via oximes by Beckmann rearrangement
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07D—HETEROCYCLIC COMPOUNDS
- C07D201/00—Preparation, separation, purification or stabilisation of unsubstituted lactams
- C07D201/16—Separation or purification
-
- 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
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P20/00—Technologies relating to chemical industry
- Y02P20/50—Improvements relating to the production of bulk chemicals
- Y02P20/52—Improvements relating to the production of bulk chemicals using catalysts, e.g. selective catalysts
Abstract
The invention provides a method for synthesizing caprolactam through Beckmann rearrangement reaction, which is characterized in that cyclohexanone oxime is used as a raw material, fuming sulfuric acid is used as a catalyst, a specific solvent is selected through designing a special process route, reactants are dissolved into a homogeneous phase through the solvent, the utilization rate of acidity in the fuming sulfuric acid is obviously improved, and sulfuric acid and the solvent are separated through ammonium sulfate salt precipitation, so that the solvent can be repeatedly used. Compared with the prior art, the method can obviously reduce the byproduct of ammonium sulfate, has the advantages of mild reaction conditions, high yield and the like, and is suitable for industrial production.
Description
Technical Field
The invention belongs to the technical field of chemical synthesis, and particularly relates to a catalyst for preparing caprolactam through Beckmann rearrangement and a preparation method thereof.
Background
Caprolactam is an important organic chemical raw material, and is mainly used as a monomer of a high polymer due to a special structure, and polyamide 6(PA6) chips are produced through polymerization. The caprolactam material can be used for producing nylon plastics, cotton fiber, artificial leather and other related products, has very obvious application effect in various medical fields, and can be used for producing antiplatelet and other related medicaments. The PA6 slices with different brands have different performances and different application fields, and the processed and molded PA6 is widely applied to the fields of textiles, packaging, automobiles, electronics, machinery and the like.
The raw material route for caprolactam is mainly benzene, phenol and toluene. The toluene path in the three raw materials has the highest capacity, and is the world's leading caprolactam production method. The technology of DSM company in the Netherlands is taken as a representative, cyclohexanone oxime is synthesized by preparing cyclohexanone, and caprolactam is obtained by Beckmann rearrangement. In recent years, the caprolactam production technology in China is greatly improved, and the domestic productivity is greatly expanded.
The Beckmann rearrangement (Beckmann rearrangement) is an acid-catalyzed rearrangement in which the oxime reactant is rearranged to an amide under the catalysis of an acid. Various beckmann rearrangement catalysts are available, including inorganic acids, organic acids, acidic molecular sieves, ionic liquids, and the like. These catalyst schemes have been studied in detail.
In the industrial production of caprolactam, sulfuric acid or oleum is often used as a catalyst, and caprolactam is produced by the beckmann rearrangement reaction of cyclohexanone oxime in the presence of sulfuric acid or oleum. The process generally adopts a mode of material external circulation heat transfer, namely, fuming sulfuric acid is added into a system from a circulating pump inlet in a rearrangement reactor and mixed with rearrangement liquid, heat is transferred out of a reaction system through a circulating pipeline heat exchanger, and the circulation liquid with the reduced temperature enters a mixer and is rapidly mixed with added cyclohexanone oxime to react to form heavy liquid. The process is mature and simple, so that the caprolactam is basically produced by the method in industry.
The rearrangement reaction of cyclohexanone oxime in the presence of oleum is a strong exothermic reaction, the reaction speed is high, the reaction is violent, and a large amount of impurities are generated due to poor system configuration, so that the product quality of caprolactam is seriously influenced. More seriously, the process also produces a large amount of ammonium sulfate, and 1.4 to 1.8 tons of ammonium sulfate are produced per 1 ton of caprolactam. Ammonium sulfate is a chemical fertilizer, which is sold at a price lower than the cost price, and a large amount of ammonium sulfate by-products cause an increase in the cost. Therefore, the process needs to be improved, the consumption of sulfuric acid and ammonia gas is reduced, and the yield of the by-product ammonium sulfate is reduced, so that the production cost is reduced.
In patent US4257950, cyclohexanone oxime is subjected to beckmann rearrangement using nicotinic acid as a catalyst to produce caprolactam by dissolving in a solvent which is inert to nicotinic acid and insoluble in water and nicotinic acid, but ammonium sulfate by-produced is not reduced.
Patent CN1508128A also discloses a method for preparing caprolactam from cyclohexanone oxime and nicotinic acid or anhydrous sulfuric acid in the presence of a solvent inert to nicotinic acid or sulfuric acid, which reduces the by-product ammonium sulfate, but the used solvent is not separated effectively, resulting in acid residue in the solvent, difficult reuse and waste.
Disclosure of Invention
The method takes cyclohexanone-oxime as a raw material and takes oleum as a catalyst, the reactants are dissolved into a homogeneous phase through a solvent, the utilization rate of acidity in the oleum is obviously improved, and the sulfuric acid and the solvent are separated through ammonium sulfate precipitation, so that the solvent can be repeatedly used. Compared with the prior art, the method can obviously reduce the byproduct of ammonium sulfate, has the advantages of mild reaction conditions, high yield and the like, and is suitable for industrial production.
Specifically, the method for synthesizing caprolactam through Beckmann rearrangement comprises the following steps of:
(1) placing cyclohexanone oxime in a solvent, and stirring until the cyclohexanone oxime is dissolved;
(2) putting fuming sulfuric acid into a solvent, and stirring until the fuming sulfuric acid is dissolved;
(3) preheating the solutions obtained in the steps (1) and (2), gradually adding the cyclohexanone oxime solution into fuming sulfuric acid solution to obtain two-phase mixed solution, stirring until the two-phase mixed solution is uniformly mixed, and keeping the temperature to obtain caprolactam-sulfuric acid solution;
(4) and (4) injecting the caprolactam-sulfuric acid solution obtained in the step (3) into a saturated ammonium sulfate aqueous solution, introducing enough ammonia gas to be neutral, and completely separating the solvent, the caprolactam and the ammonium sulfate aqueous solution by salting out. The separated liquid is three phases which are respectively a caprolactam solvent phase, a saturated ammonium sulfate water solution phase and ammonium sulfate crystallization;
(5) carrying out flash evaporation on the caprolactam solvent phase obtained in the step (4) to remove the solvent in the caprolactam phase to obtain a caprolactam water solution; the solvent can be recycled to the step (1) and the step (2);
(6) adding the caprolactam water solution obtained in the step (5) into benzene, and stirring and extracting to obtain a caprolactam-benzene phase and a water phase;
(7) and (5) adding the caprolactam-benzene phase obtained in the step (6) into water, stirring and extracting to obtain a benzene phase and a caprolactam-water phase, and rectifying the water phase to remove water to obtain caprolactam.
In the step (1), the selected solvent is one or more of 1,1,2, 2-tetrachloroethane, 1-difluoro-1, 2-dichloroethane, acetonitrile, N-dimethylformamide, acetone, butanone, dioxane and tert-butanol.
In the step (1), the mass concentration of the cyclohexanone oxime is 5-50 wt%, and the preferable concentration is 25-40 wt%.
In the step (2), the selected solvent is the same as the solvent in the step (1), and SO in oleum is used 3 The concentration is 3 to 30%, preferably 12 to 20%. The concentration of the fuming sulfuric acid in the solvent is 30-80 wt%, and the preferable concentration is 40-50 wt%.
In the step (3), the mass ratio of the cyclohexanone oxime to the oleum is 0.5-4, preferably 1.2-2.2. The reaction temperature is 50-270 ℃, preferably 80-180 ℃, and the reaction time is 0.5-30 min, preferably 5-15 min;
in the step (4), the mass ratio of the caprolactam-sulfuric acid solution to the saturated ammonium sulfate solution is 1:1, the pH value of a water phase after ammonia gas is introduced is 5-9, and the neutralization crystallization reaction temperature is 30-70 ℃, preferably 40-50 ℃;
in the step (5), the flash evaporation temperature is 40-90 ℃, the pressure is 0.1-100 kPa, and the content of the solvent in the flash evaporated caprolactam solution is less than 0.01%;
in the step (6), the mass ratio of the caprolactam phase to the benzene is 0.5-3, preferably 1-2. The treatment temperature is 30-70 ℃, and preferably 40-50 ℃;
in the step (7), the mass ratio of the caprolactam-benzene phase to the water is 1-5, preferably 2-3, and preferably 20-40 ℃;
has the advantages that:
according to the method for synthesizing caprolactam through Beckmann rearrangement provided by the invention, a special process route is designed, a specific solvent is selected, reactants are dissolved into a homogeneous phase through the solvent, the utilization rate of acidity in fuming sulfuric acid is obviously improved, and the sulfuric acid and the solvent are separated through ammonium sulfate precipitation, so that the solvent can be repeatedly used. Compared with the prior art, the method can obviously reduce the byproduct of ammonium sulfate, has the advantages of mild reaction conditions, high yield and the like, and is suitable for industrial production.
Drawings
FIG. 1 is a process flow diagram of a process for synthesizing caprolactam by Beckmann rearrangement according to the present invention.
Detailed Description
The present invention will be described in detail with reference to examples.
Example 1
20kg of cyclohexanone oxime was placed in 50kg of 1,1,2, 2-tetrachloroethane and stirred until completely dissolved, and then preheated to 150 ℃ to obtain 13kg of 10% oleum, which was placed in 14kg of 1,1,2, 2-tetrachloroethane. It was preheated to 150 ℃. Adding the cyclohexanone oxime solution into fuming sulfuric acid solution, continuously stirring and keeping the reaction temperature at 150 ℃, and stopping the reaction after reacting for 15min to obtain the caprolactam-sulfuric acid solution.
The caprolactam-sulfuric acid solution was added to 97kg of saturated aqueous ammonium sulfate solution, maintaining the temperature at 50 ℃. Stirring was started and ammonia gas was gradually introduced thereinto, the liquid was divided into three phases after the introduction, and the pH of the lower aqueous phase was 6.02. The upper caprolactam phase (95.1 kg) was taken and placed in a flash tank at 50 ℃ under 101kPa, and after flash evaporation, the 1,1,2, 2-tetrachloroethane solvent was removed to obtain 31.8kg of an aqueous caprolactam solution. The aqueous caprolactam solution was placed in 20kg of benzene, maintained at 45 ℃ and stirred until the extraction was complete. Taking 42.2kg of the upper caprolactam-benzene phase, placing the upper caprolactam-benzene phase in 20kg of water, keeping the temperature at 25 ℃, and stirring until extraction is completed to obtain a caprolactam water solution.
Through analysis, the conversion rate of the cyclohexanone oxime is 100 percent, the selectivity of the caprolactam is 99.7 percent, the yield of the caprolactam after neutralization crystallization-extraction treatment is 19.2kg, the yield is 96.3 percent, the amount of the ammonium sulfate byproduct is 17.9kg, and 0.93kg of the ammonium sulfate byproduct is produced per kg of the caprolactam.
Example 2
20kg of cyclohexanone oxime was placed in 60kg of tert-butanol, stirred until completely dissolved, preheated to 170 ℃ and 15kg of 8% oleum were taken and placed in 27kg of tert-butanol. It was preheated to 170 ℃. Adding the cyclohexanone oxime solution into fuming sulfuric acid solution, continuously stirring and keeping the reaction temperature at 170 ℃, and stopping the reaction after reacting for 10min to obtain the caprolactam-sulfuric acid solution.
The caprolactam-sulfuric acid solution was added to 122kg of saturated aqueous ammonium sulfate solution, maintaining the temperature at 40 ℃. Stirring was started and ammonia gas was gradually introduced thereinto, and the liquid was divided into three phases after the introduction, and the pH of the lower aqueous phase was 5.88. Taking 110.0kg of caprolactam phase at the upper layer, placing the caprolactam phase in a flash tank, keeping the temperature at 40 ℃ and the absolute pressure at 40kPa, and removing the tert-butyl alcohol solvent after flash evaporation to obtain 32.9kg of caprolactam water solution. The aqueous caprolactam solution was placed in 25kg of benzene, maintained at 45 ℃ and stirred until extraction was complete. Taking 46.7kg of caprolactam-benzene phase on the upper layer, placing the caprolactam-benzene phase in 20kg of water, keeping the temperature at 25 ℃, and stirring until extraction is completed to obtain a caprolactam water solution.
Through analysis, the conversion rate of the cyclohexanone oxime is 100 percent, the selectivity of the caprolactam is 99.8 percent, the yield of the caprolactam after neutralization crystallization-extraction treatment is 18.9kg, the yield is 94.5 percent, the amount of the ammonium sulfate byproduct is 20.7kg, and the ammonium sulfate byproduct per kg of the caprolactam is 1.09 kg.
Example 3
20kg of cyclohexanone oxime was put into 30kg of 1, 1-difluoro-1, 2-dichloroethane, stirred to be completely dissolved, and then preheated to 180 ℃ and 12kg of 8% oleum was taken and put into 12kg of 1, 1-difluoro-1, 2-dichloroethane. It was preheated to 180 ℃. Adding the cyclohexanone oxime solution into fuming sulfuric acid solution, continuously stirring and keeping the reaction temperature at 180 ℃, and stopping the reaction after reacting for 8min to obtain the caprolactam-sulfuric acid solution.
The caprolactam-sulfuric acid solution was added to 74kg of saturated aqueous ammonium sulfate solution, maintaining the temperature at 50 ℃. Stirring was started and ammonia gas was gradually introduced thereinto, the liquid separated into three phases after the introduction, and the pH of the lower aqueous phase was 6.85. The upper caprolactam phase (75 kg) was taken and placed in a flash tank at 50 ℃ under 25kPa absolute pressure, and after flash evaporation, the 1, 1-difluoro-1, 2-dichloroethane solvent was removed to give 33.2kg of caprolactam aqueous solution. The aqueous caprolactam solution was placed in 30kg of benzene, the temperature was maintained at 40 ℃ and stirred until the extraction was complete. Taking 42.7kg of the caprolactam-benzene phase on the upper layer, placing the caprolactam-benzene phase in 20kg of water, keeping the temperature at 25 ℃, and stirring until the extraction is finished to obtain the aqueous solution of caprolactam.
Through analysis, the conversion rate of the cyclohexanone oxime is 100 percent, the selectivity of the caprolactam is 99.7 percent, the yield of the caprolactam after neutralization crystallization-extraction treatment is 19.7kg, the yield is 98.5 percent, the amount of the by-product ammonium sulfate is 16.5kg, and the by-product ammonium sulfate per kg of the caprolactam is 0.84 kg.
Example 4
20kg of cyclohexanone oxime was placed in 55kg of acetonitrile, stirred until completely dissolved, preheated to 100 ℃ and 15kg of 12% oleum was taken and placed in 15kg of acetonitrile. It was preheated to 100 ℃. Adding the cyclohexanone oxime solution into fuming sulfuric acid solution, continuously stirring and keeping the reaction temperature at 200 ℃, and stopping the reaction after reacting for 8min to obtain the caprolactam-sulfuric acid solution.
The caprolactam-sulfuric acid solution was added to 105kg of saturated aqueous ammonium sulfate solution, maintaining the temperature at 50 ℃. Stirring was started and ammonia gas was gradually introduced thereinto, the liquid separated into three phases after the introduction, and the pH of the lower aqueous phase was 5.99. The upper caprolactam phase is taken and 101.2kg in total, placed in a flash tank, the temperature is kept at 50 ℃, the absolute pressure is 30kPa, and after flash evaporation, the acetonitrile solvent is removed to obtain 31.5kg of caprolactam water solution. The aqueous caprolactam solution was placed in 25kg of benzene, the temperature was maintained at 40 ℃ and stirred until the extraction was complete. Taking 43.8kg of the caprolactam-benzene phase on the upper layer, placing the caprolactam-benzene phase in 20kg of water, keeping the temperature at 25 ℃, and stirring until the extraction is finished to obtain the aqueous solution of caprolactam.
Through analysis, the conversion rate of the cyclohexanone oxime is 100 percent, the selectivity of the caprolactam is 95.1 percent, the yield of the caprolactam after neutralization crystallization-extraction treatment is 18.6kg, the yield is 93.2 percent, the amount of the ammonium sulfate byproduct is 20.8kg, and 1.12kg of the ammonium sulfate byproduct is produced per kg of the caprolactam.
Example 5
20kg of cyclohexanone oxime was placed in 60kg of dioxane, stirred until completely dissolved, preheated to 110 ℃ and 12kg of 18% oleum was taken and placed in 12kg of dioxane. It was preheated to 160 ℃. Adding the cyclohexanone oxime solution into fuming sulfuric acid solution, continuously stirring and keeping the reaction temperature at 160 ℃, and stopping the reaction after reacting for 13min to obtain the caprolactam-sulfuric acid solution.
The caprolactam-sulfuric acid solution was added to 104kg of saturated aqueous ammonium sulfate solution, maintaining the temperature at 50 ℃. Stirring was started and ammonia gas was gradually introduced thereinto, and the liquid separated into three phases after the introduction, and the pH of the lower aqueous phase was 6.34. The upper caprolactam phase was taken and 103.7kg in total, placed in a flash tank at 50 ℃ under 20kPa absolute pressure, and the dioxane solvent was removed after flash evaporation to give 25.6kg of aqueous caprolactam solution. The aqueous caprolactam solution was placed in 20kg of benzene, the temperature was maintained at 40 ℃ and stirred until the extraction was complete. Taking 43.2kg of the upper caprolactam-benzene phase, placing the upper caprolactam-benzene phase in 20kg of water, keeping the temperature at 30 ℃, and stirring until the extraction is finished to obtain the aqueous solution of caprolactam.
Through analysis, the conversion rate of the cyclohexanone oxime is 100 percent, the selectivity of the caprolactam is 97.8 percent, the yield of the caprolactam after neutralization crystallization-extraction treatment is 19.1kg, the yield is 95.5 percent, the amount of the ammonium sulfate byproduct is 16.82kg, and 0.88kg of the ammonium sulfate byproduct is produced per kg of the caprolactam.
Example 6
20kg of cyclohexanone oxime was placed in 50kg of butanone, stirred until completely dissolved, preheated to 170 ℃ and 17kg of 10% oleum was taken and placed in 20kg of butanone. It was preheated to 170 ℃. Adding the cyclohexanone oxime solution into fuming sulfuric acid solution, continuously stirring and keeping the reaction temperature at 170 ℃, and stopping the reaction after 7min of reaction to obtain the caprolactam-sulfuric acid solution.
The caprolactam-sulfuric acid solution was added to 107kg of saturated aqueous ammonium sulfate solution, maintaining the temperature at 50 ℃. Stirring was started and ammonia gas was gradually introduced thereinto, the liquid separated into three phases after the introduction, and the pH of the lower aqueous phase was 6.25. Taking 100.9kg of caprolactam phase at the upper layer, placing the caprolactam phase in a flash tank, keeping the temperature at 40 ℃ and the absolute pressure at 10kPa, and removing the butanone solvent after flash evaporation to obtain 33.2kg of caprolactam water solution. The aqueous caprolactam solution was placed in 25kg of benzene, the temperature was maintained at 40 ℃ and stirred until the extraction was complete. The caprolactam-benzene phase on the upper layer is taken and added into 41.6kg of water of 20kg, the temperature is kept at 30 ℃, and the mixture is stirred until the extraction is finished, so that the aqueous solution of caprolactam is obtained.
Through analysis, the conversion rate of the cyclohexanone oxime is 100 percent, the selectivity of the caprolactam is 98.3 percent, the yield of the caprolactam after neutralization crystallization-extraction treatment is 19.3kg, the yield is 96.5 percent, the amount of the by-product ammonium sulfate is 23.41kg, and the by-product ammonium sulfate per kg of the caprolactam is 1.21 kg.
Comparative example 1
20kg of cyclohexanone oxime was preheated to 100 ℃ and 20kg of 10% oleum was taken and preheated to 100 ℃. Slowly spraying and adding the cyclohexanone oxime solution into fuming sulfuric acid, continuously stirring, keeping the reaction temperature at 100 ℃, and stopping the reaction after 5min of reaction to obtain a caprolactam-sulfuric acid phase. The caprolactam-sulfuric acid phase was placed in 40kg of saturated aqueous ammonium sulfate solution, the temperature was kept at 45 ℃, stirring was started and ammonia gas was gradually introduced thereinto, the liquid was divided into three phases after introduction, and the pH of the lower aqueous phase was 6.0. The upper caprolactam phase was taken 31.7kg in total, placed in 30kg benzene, kept at 45 ℃ and stirred until extraction was complete. Taking 54.1kg of caprolactam-benzene phase on the upper layer, placing the caprolactam-benzene phase in 20kg of water, keeping the temperature at 30 ℃, and stirring until the extraction is finished to obtain a caprolactam water solution.
Through analysis, the conversion rate of the cyclohexanone oxime is 100 percent, the selectivity of the caprolactam is 98.7 percent, the yield of the caprolactam after neutralization crystallization-extraction treatment is 19.4kg, the yield is 96.8 percent, the amount of the ammonium sulfate byproduct is 27.6kg, and 1.42kg of the ammonium sulfate byproduct is produced per kg of the caprolactam.
Comparative example 2
20kg of cyclohexanone oxime was preheated to 100 ℃ and 12.5kg of 10% oleum were taken and preheated to 100 ℃. Slowly spraying and adding the cyclohexanone oxime solution into fuming sulfuric acid, continuously stirring, keeping the reaction temperature at 100 ℃, and stopping the reaction after 5min of reaction to obtain a caprolactam-sulfuric acid phase. The caprolactam-sulfuric acid phase was placed in 20kg of saturated aqueous ammonium sulfate solution, the temperature was kept at 45 ℃, stirring was started and ammonia gas was gradually introduced thereinto, the liquid was divided into three phases after introduction, and the pH of the lower aqueous phase was 6.1. Taking 30.1kg of caprolactam phase at the upper layer, placing the caprolactam phase in 30kg of benzene, keeping the temperature at 45 ℃, and stirring until the extraction is finished. Taking 50.6kg of the caprolactam-benzene phase on the upper layer, placing the caprolactam-benzene phase in 20kg of water, keeping the temperature at 30 ℃, and stirring until the extraction is finished to obtain the aqueous solution of caprolactam.
Through analysis, the conversion rate of the cyclohexanone oxime is 100 percent, the selectivity of the caprolactam is 69.8 percent, the yield of the caprolactam after neutralization crystallization-extraction treatment is 12.7kg, the yield is 63.4 percent, the amount of the ammonium sulfate byproduct is 17.2kg, and the ammonium sulfate byproduct per kg of the caprolactam is 1.35 kg.
Description of the drawings: in comparative example 1, no solvent was used, and the amount of sulfuric acid added was large, indicating that the yield was high, but the amount of ammonium sulfate produced was large, in comparative example 2, no solvent was used, and the amount of sulfuric acid added was small, indicating that the amount of sulfuric acid produced was small, but the yield was low. This indicates that the yield and by-product are hardly both obtained without adding a solvent.
Comparative example 3
20kg of cyclohexanone oxime was placed in 50kg of trichloroethylene, stirred until completely dissolved, preheated to 150 ℃ and 13kg of 10% oleum was taken and placed in 14kg of trichloroethylene. It was preheated to 150 ℃. Adding the cyclohexanone oxime solution into fuming sulfuric acid solution, continuously stirring and keeping the reaction temperature at 150 ℃, and stopping the reaction after reacting for 15min to obtain solution containing caprolactam-sulfate. At this point, the trichloroethylene is able to dissolve part of the caprolactam-sulphate, so that the product is divided into two phases, both of which dissolve caprolactam-sulphate.
The product solution was added to 97kg of saturated aqueous ammonium sulfate solution, and the temperature was maintained at 50 ℃. Stirring and gradually introducing ammonia gas, separating the liquid into three phases after introduction, precipitating the lower layer with ammonium sulfate, adjusting pH of the water phase in the middle layer to 6.30, and adjusting pH of the upper layer with organic solution phase containing caprolactam. The organic solution phase of the upper layer was analyzed to contain caprolactam-sulfate and was difficult to remove.
96.8kg of caprolactam phase at the upper layer is taken out and placed in a flash tank, the temperature is kept at 50 ℃, the absolute pressure is 101kPa, and trichloroethylene is removed after flash evaporation, so that 32.6kg of caprolactam water solution is obtained. The aqueous caprolactam solution was placed in 20kg of benzene, maintained at 45 ℃ and stirred until the extraction was complete. Taking 38.8kg of the caprolactam-benzene phase on the upper layer, placing the caprolactam-benzene phase in 20kg of water, keeping the temperature at 25 ℃, and stirring until the extraction is finished to obtain the aqueous solution of caprolactam.
Analysis shows that the conversion rate of the cyclohexanone oxime is 100 percent, the selectivity of the caprolactam is 99.7 percent, as the caprolactam-sulfate is not removed, part of the caprolactam flows away along with the solvent, the yield of the caprolactam is 18.2kg, the yield is 91.0 percent, the quantity of the ammonium sulfate byproduct is 16.8kg, and each kilogram of the caprolactam has 0.92kg of the ammonium sulfate byproduct. Although the by-product ammonium sulfate is reduced, the yield of caprolactam is low. And the solvent is polluted and is difficult to be repeatedly beneficial.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.
Claims (10)
1. A method for synthesizing caprolactam through Beckmann rearrangement is characterized by comprising the following steps:
(1) placing cyclohexanone oxime in a solvent, and stirring until the cyclohexanone oxime is dissolved;
(2) putting fuming sulfuric acid into a solvent, and stirring until the fuming sulfuric acid is dissolved;
(3) preheating the solution obtained in the step (1) and the step (2), gradually adding the cyclohexanone oxime solution into a fuming sulfuric acid solution to obtain a two-phase mixed solution, stirring until the two-phase mixed solution is uniformly mixed, and keeping the temperature to obtain a caprolactam-sulfuric acid solution;
(4) and (4) injecting the caprolactam-sulfuric acid solution obtained in the step (3) into a saturated ammonium sulfate aqueous solution, and introducing enough ammonia gas to be neutral. The solvent, caprolactam and aqueous ammonium sulfate solution are completely separated by salting out. The separated liquid is three phases which are respectively a caprolactam solvent phase, a saturated ammonium sulfate water solution phase and ammonium sulfate crystallization;
(5) carrying out flash evaporation on the caprolactam phase obtained in the step (4) to remove the solvent in the caprolactam phase to obtain a caprolactam water solution;
(6) adding the caprolactam water solution obtained in the step (5) into benzene, and stirring and extracting to obtain a caprolactam-benzene phase and a water phase;
(7) adding the caprolactam-benzene phase obtained in the step (6) into water, stirring and extracting to obtain a benzene phase and a caprolactam-water phase, and rectifying the water phase to remove water to obtain caprolactam;
the solvent in the step (1) is the same as that in the step (2), and the selected solvent is one or more of 1,1,2, 2-tetrachloroethane, 1-difluoro-1, 2-dichloroethane, acetonitrile, N-dimethylformamide, acetone, butanone, dioxane and tert-butanol.
2. The process for synthesizing caprolactam by the beckmann rearrangement according to claim 1, wherein: in the step (1), the mass concentration of the cyclohexanone oxime is 5-50 wt%, and the preferable concentration is 25-40 wt%.
3. The process for synthesizing caprolactam according to claim 1, wherein: SO in oleum used in the step (2) 3 The concentration is 3 to 30%, preferably 12 to 20%. The concentration of the fuming sulfuric acid in the solvent is 30-80 wt%, and the preferable concentration is 40-50 wt%.
4. The process for synthesizing caprolactam by the beckmann rearrangement according to claim 1, wherein: in the step (3), the preheating temperature of the cyclohexanone oxime solution is 50-270 ℃, preferably 80-180 ℃, and the preheating temperature of the fuming sulfuric acid solution is 50-270 ℃, preferably 80-180 ℃.
5. The process for synthesizing caprolactam by the beckmann rearrangement according to claim 1, wherein: in the step (3), the mass ratio of the cyclohexanone oxime to the oleum is 0.5-4, preferably 1.2-2.2.
6. The process for synthesizing caprolactam by the beckmann rearrangement according to claim 1, wherein: in the step (2), the reaction temperature is 50-270 ℃, preferably 80-180 ℃, and the reaction time is 0.5-30 min, preferably 5-15 min.
7. The process for synthesizing caprolactam according to claim 1, wherein: in the step (4), the mass ratio of the caprolactam-sulfuric acid solution to the saturated ammonium sulfate solution is 1:1, the pH value of a water phase after ammonia gas is introduced is 4-10, and the temperature of the neutralization crystallization reaction is 30-70 ℃, preferably 40-50 ℃.
8. The process for synthesizing caprolactam by the beckmann rearrangement according to claim 1, wherein: in the step (5), the flash evaporation temperature is 40-90 ℃, the pressure is 0.1-100 kPa, and the content of the solvent in the flash evaporated caprolactam solution is less than 0.01%.
9. The process for synthesizing caprolactam by the beckmann rearrangement according to claim 1, wherein: in the step (6), the mass ratio of the caprolactam phase to the benzene is 0.5-3, preferably 1-2. The treatment temperature is 30-70 ℃, and preferably 40-50 ℃.
10. The process for synthesizing caprolactam by the beckmann rearrangement according to claim 1, wherein: in the step (7), the mass ratio of the caprolactam-benzene phase to the water is 1-5, preferably 2-3, and preferably 20-40 ℃.
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Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB996322A (en) * | 1961-04-27 | 1965-06-23 | Basf Ag | Simultaneous recovery of pure ammonium sulphate and pure lactams from rearrangement mixtures of alicyclic ketoximes |
| JPS5360900A (en) * | 1976-11-10 | 1978-05-31 | Basf Ag | Method of obtainig pure large crystal ammoniumsulfate |
| US4138472A (en) * | 1976-11-10 | 1979-02-06 | Basf Aktiengesellschaft | Process for obtaining coarsely crystalline pure ammonium sulfate |
| CN104356039A (en) * | 2014-11-10 | 2015-02-18 | 河北美邦工程科技有限公司 | Preparation process of caprolactam |
| CN105408313A (en) * | 2013-07-26 | 2016-03-16 | Capiii有限公司 | Continuous process for recovery of caprolactam and crystalline ammonium sulfate |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3635363A1 (en) * | 1986-10-17 | 1988-04-21 | Basf Ag | METHOD FOR NEUTRALIZING REACTION MIXTURES OBTAINED BY BECKMANN'S RESTORATION OF CYCLOHEXANONOXIM |
| CN1242988C (en) * | 2002-12-13 | 2006-02-22 | 中国石油化工股份有限公司 | Method for preparing caprolactam |
| CN104387322A (en) * | 2014-10-21 | 2015-03-04 | 湖南百利工程科技股份有限公司 | Preparation method for caprolactam with low byproducts of ammonium sulfate |
| CN104910071A (en) * | 2015-05-08 | 2015-09-16 | 河北美邦工程科技股份有限公司 | Caprolactam preparation method |
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- 2022-09-22 WO PCT/CN2022/120387 patent/WO2024000849A1/en unknown
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB996322A (en) * | 1961-04-27 | 1965-06-23 | Basf Ag | Simultaneous recovery of pure ammonium sulphate and pure lactams from rearrangement mixtures of alicyclic ketoximes |
| JPS5360900A (en) * | 1976-11-10 | 1978-05-31 | Basf Ag | Method of obtainig pure large crystal ammoniumsulfate |
| US4138472A (en) * | 1976-11-10 | 1979-02-06 | Basf Aktiengesellschaft | Process for obtaining coarsely crystalline pure ammonium sulfate |
| CN105408313A (en) * | 2013-07-26 | 2016-03-16 | Capiii有限公司 | Continuous process for recovery of caprolactam and crystalline ammonium sulfate |
| CN104356039A (en) * | 2014-11-10 | 2015-02-18 | 河北美邦工程科技有限公司 | Preparation process of caprolactam |
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