CN115093354B - 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 232
- 238000000034 method Methods 0.000 title claims abstract description 37
- 238000006237 Beckmann rearrangement reaction Methods 0.000 title claims abstract description 31
- 230000002194 synthesizing effect Effects 0.000 title claims abstract description 24
- VEZUQRBDRNJBJY-UHFFFAOYSA-N cyclohexanone oxime Chemical compound ON=C1CCCCC1 VEZUQRBDRNJBJY-UHFFFAOYSA-N 0.000 claims abstract description 100
- BFNBIHQBYMNNAN-UHFFFAOYSA-N ammonium sulfate Chemical compound N.N.OS(O)(=O)=O BFNBIHQBYMNNAN-UHFFFAOYSA-N 0.000 claims abstract description 52
- 239000002904 solvent Substances 0.000 claims abstract description 49
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims abstract description 43
- 229910052921 ammonium sulfate Inorganic materials 0.000 claims abstract description 43
- 235000011130 ammonium sulphate Nutrition 0.000 claims abstract description 43
- 238000006243 chemical reaction Methods 0.000 claims abstract description 42
- 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 42
- 238000005185 salting out Methods 0.000 claims abstract description 5
- 239000000243 solution Substances 0.000 claims description 67
- UHOVQNZJYSORNB-UHFFFAOYSA-N Benzene Chemical compound C1=CC=CC=C1 UHOVQNZJYSORNB-UHFFFAOYSA-N 0.000 claims description 51
- 238000003756 stirring Methods 0.000 claims description 32
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 30
- 239000007864 aqueous solution Substances 0.000 claims description 28
- 238000000605 extraction Methods 0.000 claims description 27
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 claims description 20
- IJQAOQPOJZUGIA-UHFFFAOYSA-N azepan-2-one benzene Chemical compound c1ccccc1.O=C1CCCCCN1 IJQAOQPOJZUGIA-UHFFFAOYSA-N 0.000 claims description 20
- WEVYAHXRMPXWCK-UHFFFAOYSA-N Acetonitrile Chemical compound CC#N WEVYAHXRMPXWCK-UHFFFAOYSA-N 0.000 claims description 15
- 239000007788 liquid Substances 0.000 claims description 14
- 238000006386 neutralization reaction Methods 0.000 claims description 11
- ZWEHNKRNPOVVGH-UHFFFAOYSA-N 2-Butanone Chemical compound CCC(C)=O ZWEHNKRNPOVVGH-UHFFFAOYSA-N 0.000 claims description 10
- DKGAVHZHDRPRBM-UHFFFAOYSA-N Tert-Butanol Chemical compound CC(C)(C)O DKGAVHZHDRPRBM-UHFFFAOYSA-N 0.000 claims description 9
- 238000001704 evaporation Methods 0.000 claims description 9
- 230000008020 evaporation Effects 0.000 claims description 9
- RYHBNJHYFVUHQT-UHFFFAOYSA-N 1,4-Dioxane Chemical compound C1COCCO1 RYHBNJHYFVUHQT-UHFFFAOYSA-N 0.000 claims description 5
- 238000002425 crystallisation Methods 0.000 claims description 5
- 230000008025 crystallization Effects 0.000 claims description 5
- CSCPPACGZOOCGX-UHFFFAOYSA-N Acetone Chemical compound CC(C)=O CSCPPACGZOOCGX-UHFFFAOYSA-N 0.000 claims description 4
- AWSFEOSAIZJXLG-UHFFFAOYSA-N azepan-2-one;hydrate Chemical compound O.O=C1CCCCCN1 AWSFEOSAIZJXLG-UHFFFAOYSA-N 0.000 claims description 4
- 239000011259 mixed solution Substances 0.000 claims description 4
- 230000035484 reaction time Effects 0.000 claims description 3
- ZMXDDKWLCZADIW-UHFFFAOYSA-N N,N-Dimethylformamide Chemical compound CN(C)C=O ZMXDDKWLCZADIW-UHFFFAOYSA-N 0.000 claims description 2
- 239000006227 byproduct Substances 0.000 abstract description 27
- 239000003054 catalyst Substances 0.000 abstract description 7
- 230000008569 process Effects 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
- ROOXNKNUYICQNP-UHFFFAOYSA-N ammonium persulfate Chemical compound [NH4+].[NH4+].[O-]S(=O)(=O)OOS([O-])(=O)=O ROOXNKNUYICQNP-UHFFFAOYSA-N 0.000 abstract 2
- 229910001870 ammonium persulfate Inorganic materials 0.000 abstract 1
- 239000012071 phase Substances 0.000 description 64
- 239000000203 mixture Substances 0.000 description 13
- 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 10
- 229920006395 saturated elastomer Polymers 0.000 description 7
- YXFVVABEGXRONW-UHFFFAOYSA-N Toluene Chemical compound CC1=CC=CC=C1 YXFVVABEGXRONW-UHFFFAOYSA-N 0.000 description 6
- HIGZEFHDFAMPND-UHFFFAOYSA-N azepan-2-one;sulfuric acid Chemical compound OS(O)(=O)=O.O=C1CCCCCN1 HIGZEFHDFAMPND-UHFFFAOYSA-N 0.000 description 5
- 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
- JHIVVAPYMSGYDF-UHFFFAOYSA-N cyclohexanone Chemical compound O=C1CCCCC1 JHIVVAPYMSGYDF-UHFFFAOYSA-N 0.000 description 4
- 238000004519 manufacturing process Methods 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
- 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
- 239000008346 aqueous phase Substances 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 238000006462 rearrangement reaction Methods 0.000 description 2
- 238000005507 spraying Methods 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
- 238000006555 catalytic reaction Methods 0.000 description 1
- 239000013064 chemical raw material Substances 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000004090 dissolution Methods 0.000 description 1
- 229940079593 drug Drugs 0.000 description 1
- 239000003814 drug Substances 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000005516 engineering process Methods 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
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 239000002808 molecular sieve Substances 0.000 description 1
- 239000000178 monomer Substances 0.000 description 1
- 230000007935 neutral effect Effects 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
- 238000002360 preparation method Methods 0.000 description 1
- 230000036632 reaction speed Effects 0.000 description 1
- 239000013049 sediment Substances 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
- 238000009987 spinning Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 238000003786 synthesis reaction Methods 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
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
According to the method for synthesizing caprolactam by the Beckmann rearrangement reaction, which is provided by the invention, the Beckmann rearrangement reaction with cyclohexanone oxime as a raw material and fuming sulfuric acid as a catalyst is carried out, a specific process route is designed, a specific solvent is selected, reactants are dissolved into a homogeneous phase by the solvent, the utilization rate of acidity in the fuming sulfuric acid is obviously improved, and sulfuric acid and the solvent are separated by ammonium persulfate salting out, so that the solvent can be reused. 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 by 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 (PA 6) slices are formed through polymerization. The caprolactam material can be used for producing nylon plastics, cotton fiber, artificial leather and other related products, has obvious application effect in various large medical fields, and can be used for producing related medicines such as antiplatelet and the like. 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 spinning, packaging, automobiles, electronics, machinery and the like.
The raw material route for caprolactam production is mainly benzene, phenol and toluene. The toluene path in the three raw materials occupies the highest productivity and is the most dominant caprolactam production method in the world. The cyclohexanone is synthesized by preparing cyclohexanone to synthesize cyclohexanone oxime, and the cyclohexanone oxime is rearranged by Beckmann to obtain caprolactam. In recent years, the caprolactam production technology in China has greatly advanced, and the domestic productivity is greatly expanded.
The Beckmann rearrangement reaction is an acid-catalyzed rearrangement reaction in which the oxime reactant rearranges to an amide under the catalysis of an acid. There are a variety of beckmann rearrangement catalysts 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 a beckmann rearrangement of cyclohexanone oxime in the presence of sulfuric acid or oleum. The process generally adopts a material external circulation heat removal mode, namely fuming sulfuric acid is added into a system from a circulating pump inlet in a rearrangement reactor to be mixed with rearrangement liquid, heat is removed from a reaction system through a circulating pipeline heat exchanger, and the circulation liquid with reduced temperature enters a mixer to be quickly mixed with the added cyclohexanone oxime for reaction to form a rearrangement liquid. The process is mature and simple, so that the method is basically used for producing caprolactam in industry.
The rearrangement reaction of cyclohexanone oxime in the presence of fuming sulfuric acid is a strong exothermic reaction, the reaction speed is high, the reaction is intense, a large amount of impurities can be generated due to poor system configuration, and the product quality of caprolactam is seriously affected. More seriously, the process also produces a large amount of ammonium sulfate, and 1.4 to 1.8 tons of ammonium sulfate can be produced per 1 ton of caprolactam. Ammonium sulfate is a chemical fertilizer with a selling price lower than the cost price, and a large amount of by-products of ammonium sulfate cause the cost to rise. Therefore, the process needs to be improved, the consumption of sulfuric acid and ammonia gas is reduced, and the yield of byproduct ammonium sulfate is reduced so as to reduce the production cost.
In patent US4257950, cyclohexanone oxime is produced by beckmann rearrangement using nicotinic acid as a catalyst by dissolving in a solvent inert to nicotinic acid and insoluble in water and nicotinic acid, but the byproduct ammonium sulfate 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 by-product ammonium sulfate, but the used solvent is not effectively separated, so that acid residues are left in the solvent, and the solvent is difficult to reuse, thus causing waste.
Disclosure of Invention
The method uses cyclohexanone oxime as a raw material, uses fuming sulfuric acid as a catalyst in the Beckmann rearrangement reaction, dissolves reactants into homogeneous phase through a solvent, remarkably improves the utilization rate of acidity in the fuming sulfuric acid, and separates sulfuric acid and the solvent through ammonium sulfate salting-out, so that the solvent can be reused. 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 by Beckmann rearrangement reaction comprises the following steps:
(1) Placing cyclohexanone oxime in a solvent, and stirring until the cyclohexanone oxime is dissolved;
(2) Placing fuming sulfuric acid in 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 a two-phase mixed solution, stirring until the two-phase mixed solution is uniformly mixed, and preserving heat to obtain caprolactam-sulfuric acid solution;
(4) Injecting the caprolactam-sulfuric acid solution obtained in the step (3) into a saturated ammonium sulfate aqueous solution, introducing a sufficient amount of 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, namely a caprolactam solvent phase, a saturated ammonium sulfate aqueous solution phase and ammonium sulfate crystallization;
(5) Flashing the caprolactam solvent phase obtained in the step (4) to remove the solvent in the caprolactam phase and obtain an aqueous solution of caprolactam; the solvent can be recycled into 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) 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, 2-tetrachloroethane, 1-difluoro-1, 2-dichloroethane, acetonitrile, N-dimethylformamide, acetone, butanone, dioxane and tertiary butanol.
In the step (1), the mass concentration of cyclohexanone oxime is 5 to 50% by weight, preferably 25 to 40% by weight.
In the step (2), the solvent is the same as that in the step (1), and SO in fuming sulfuric acid is used 3 The concentration is 3 to 30%, preferably 12 to 20%. The fuming sulfuric acid concentration in the solvent is 30-80 wt%, preferably 40-50 wt%.
In the step (3), the mass ratio of the cyclohexanone oxime to the fuming sulfuric acid 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 the water phase after ammonia gas is introduced is 5-9, the neutralization crystallization reaction temperature is 30-70 ℃, and the preferential temperature is 40-50 ℃;
in the step (5), the flash evaporation temperature is 40-90 ℃, the pressure is 0.1-100 kPa, and the solvent content 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 ℃, preferably 40-50 ℃;
in the step (7), the mass ratio of the caprolactam-benzene phase to the water is 1-5, preferably 2-3, preferably 20-40 ℃;
the beneficial effects are that:
according to the method for synthesizing caprolactam through the Beckmann rearrangement reaction, a special process route is designed, a specific solvent is selected, reactants are dissolved into homogeneous phases through the solvent, the utilization rate of acidity in fuming sulfuric acid is remarkably improved, sulfuric acid and the solvent are separated through ammonium sulfate salting-out, and the solvent can be reused. 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 method for synthesizing caprolactam by Beckmann rearrangement reaction 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, 2-tetrachloroethane, stirred until it was completely dissolved, preheated to 150℃and 13kg of 10% strength fuming sulfuric acid was taken and placed in 14kg of 1, 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 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 is started, ammonia gas is gradually introduced into the mixture, the liquid is divided into three phases after the ammonia gas is introduced into the mixture, and the pH value of the water phase at the lower layer is 6.02. The upper caprolactam phase was taken in a total of 95.1kg and placed in a flash tank at a temperature of 50℃and an absolute pressure of 101kPa, and after flash evaporation, the 1, 2-tetrachloroethane solvent was removed to give 31.8kg of an aqueous caprolactam solution. An aqueous solution of caprolactam was placed in 20kg of benzene, kept at 45℃and stirred until extraction was completed. The upper caprolactam-benzene phase was taken to be 42.2kg in total, and placed in 20kg of water, kept at 25 ℃, and stirred until extraction was completed, to obtain an aqueous solution of caprolactam.
According to analysis, the conversion rate of cyclohexanone oxime is 100%, the selectivity of caprolactam is 99.7%, the yield of caprolactam after neutralization crystallization-extraction treatment is 19.2kg, the yield is 96.3%, the amount of byproduct ammonium sulfate is 17.9kg, and the byproduct ammonium sulfate is 0.93kg per kg of caprolactam.
Example 2
20kg of cyclohexanone oxime was placed in 60kg of t-butanol, stirred until it was completely dissolved, preheated to 170℃and 15kg of 8% strength fuming sulfuric acid was taken and placed in 27kg of t-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 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 is started, ammonia gas is gradually introduced into the mixture, the liquid is divided into three phases after the ammonia gas is introduced into the mixture, and the pH value of the water phase at the lower layer is 5.88. 110.0kg of the upper caprolactam phase was taken and placed in a flash tank, the temperature was kept at 40℃and the absolute pressure at 40kPa, and after flash evaporation, the tert-butanol solvent was removed to obtain 32.9kg of an aqueous caprolactam solution. An aqueous solution of caprolactam was placed in 25kg of benzene, kept at 45℃and stirred until extraction was completed. The upper caprolactam-benzene phase was taken up to 46.7kg and placed in 20kg of water, kept at 25 c, and stirred until extraction was completed, obtaining an aqueous solution of caprolactam.
According to analysis, the conversion rate of cyclohexanone oxime is 100%, the selectivity of caprolactam is 99.8%, the yield of caprolactam after neutralization crystallization-extraction treatment is 18.9kg, the yield is 94.5%, the byproduct ammonium sulfate amount is 20.7kg, and the byproduct ammonium sulfate per kg of caprolactam is 1.09kg.
Example 3
20kg of cyclohexanone oxime was placed in 30kg of 1, 1-difluoro-1, 2-dichloroethane, stirred until complete dissolution, preheated to 180℃and 12kg of 8% strength fuming sulfuric acid was taken and placed in 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 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 is started, ammonia gas is gradually introduced into the mixture, the liquid is divided into three phases after the ammonia gas is introduced into the mixture, and the pH value of the water phase at the lower layer is 6.85. The upper caprolactam phase was taken in 75kg and placed in a flash tank, kept at a temperature of 50℃and an absolute pressure of 25kPa, and after flash evaporation the 1, 1-difluoro-1, 2-dichloroethane solvent was removed, giving 33.2kg of an aqueous caprolactam solution. An aqueous solution of caprolactam was placed in 30kg of benzene, kept at a temperature of 40 ℃, and stirred until extraction was completed. The upper caprolactam-benzene phase was taken to be 42.7kg in total, and placed in 20kg of water, kept at 25 ℃, and stirred until extraction was completed, to obtain an aqueous solution of caprolactam.
According to analysis, the conversion rate of cyclohexanone oxime is 100%, the selectivity of caprolactam is 99.7%, the yield of caprolactam after neutralization crystallization-extraction treatment is 19.7kg, the yield is 98.5%, the amount of byproduct ammonium sulfate is 16.5kg, and the byproduct ammonium sulfate is 0.84kg per kg of caprolactam.
Example 4
20kg of cyclohexanone oxime was placed in 55kg of acetonitrile, stirred until it was completely dissolved, preheated to 100℃and 15kg of fuming sulfuric acid having a concentration of 12% 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 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 is started, ammonia gas is gradually introduced into the mixture, the liquid is divided into three phases after the ammonia gas is introduced into the mixture, and the pH value of the water phase at the lower layer is 5.99. The upper caprolactam phase was taken to be 101.2kg in total, placed in a flash tank, kept at 50℃under 30kPa absolute pressure, and the acetonitrile solvent was removed after flash evaporation to obtain 31.5kg of caprolactam aqueous solution. An aqueous solution of caprolactam was placed in 25kg of benzene, kept at a temperature of 40℃and stirred until extraction was completed. Taking 43.8kg 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 an aqueous solution of caprolactam.
According to analysis, the conversion rate of cyclohexanone oxime is 100%, the selectivity of caprolactam is 95.1%, the yield of caprolactam after neutralization crystallization-extraction treatment is 18.6kg, the yield is 93.2%, the amount of byproduct ammonium sulfate is 20.8kg, and the byproduct ammonium sulfate is 1.12kg per kg of caprolactam.
Example 5
20kg of cyclohexanone oxime was placed in 60kg of dioxane, stirred until it was completely dissolved, preheated to 110℃and 12kg of 18% strength fuming sulfuric acid 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 13min of reaction to obtain 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 is started, ammonia gas is gradually introduced into the mixture, the liquid is divided into three phases after the ammonia gas is introduced into the mixture, and the pH value of the water phase at the lower layer is 6.34. The upper caprolactam phase was taken to be 103.7kg in total, placed in a flash tank, kept at 50℃and 20kPa absolute pressure, and after flash evaporation, dioxane solvent was removed to obtain 25.6kg of caprolactam aqueous solution. An aqueous solution of caprolactam was placed in 20kg of benzene, kept at a temperature of 40 ℃, and stirred until extraction was completed. Taking 43.2kg 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 extraction is completed to obtain an aqueous solution of caprolactam.
According to analysis, the conversion rate of cyclohexanone oxime is 100%, the selectivity of caprolactam is 97.8%, the yield of caprolactam after neutralization crystallization-extraction treatment is 19.1kg, the yield is 95.5%, the amount of byproduct ammonium sulfate is 16.82kg, and the byproduct ammonium sulfate is 0.88kg per kg of caprolactam.
Example 6
20kg of cyclohexanone oxime was placed in 50kg of butanone, stirred until it was completely dissolved, preheated to 170℃and 17kg of fuming sulfuric acid having a concentration of 10% 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 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 is started, ammonia gas is gradually introduced into the mixture, the liquid is divided into three phases after the ammonia gas is introduced into the mixture, and the pH value of the water phase at the lower layer is 6.25. The upper caprolactam phase was taken to total 100.9kg and placed in a flash tank at a temperature of 40℃and an absolute pressure of 10kPa, and after flash evaporation, the butanone solvent was removed to give 33.2kg of caprolactam aqueous solution. An aqueous solution of caprolactam was placed in 25kg of benzene, kept at a temperature of 40℃and stirred until extraction was completed. Taking 41.6kg 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 extraction is completed to obtain an aqueous solution of caprolactam.
According to analysis, the conversion rate of cyclohexanone oxime is 100%, the selectivity of caprolactam is 98.3%, the yield of caprolactam after neutralization crystallization-extraction treatment is 19.3kg, the yield is 96.5%, the byproduct ammonium sulfate amount is 23.41kg, and the byproduct ammonium sulfate per kg of caprolactam is 1.21kg.
Comparative example 1
20kg of cyclohexanone oxime was preheated to 100℃and 20kg of fuming sulfuric acid having a concentration of 10% was taken and preheated to 100 ℃. Slowly spraying the cyclohexanone oxime solution into fuming sulfuric acid, continuously stirring and keeping the reaction temperature at 100 ℃, and stopping the reaction after reacting for 5min to obtain a caprolactam-sulfuric acid phase. The caprolactam-sulfuric acid phase is placed in 40kg of saturated ammonium sulfate aqueous solution, the temperature is kept at 45 ℃, stirring is started, ammonia gas is gradually introduced into the solution, the liquid is divided into three phases after the introduction, and the pH value of the lower aqueous phase is 6.0. The upper caprolactam phase was taken up in 31.7kg and placed in 30kg of benzene at 45℃and stirred until extraction was completed. The upper caprolactam-benzene phase was taken to total 54.1kg and placed in 20kg of water, kept at 30 c, and stirred until extraction was completed, to obtain an aqueous solution of caprolactam.
According to analysis, the conversion rate of cyclohexanone oxime is 100%, the selectivity of caprolactam is 98.7%, the yield of caprolactam after neutralization crystallization-extraction treatment is 19.4kg, the yield is 96.8%, the byproduct ammonium sulfate amount is 27.6kg, and the byproduct ammonium sulfate per kilogram of caprolactam is 1.42kg.
Comparative example 2
20kg of cyclohexanone oxime was preheated to 100℃and 12.5kg of fuming sulfuric acid having a concentration of 10% was taken and preheated to 100 ℃. Slowly spraying the cyclohexanone oxime solution into fuming sulfuric acid, continuously stirring and keeping the reaction temperature at 100 ℃, and stopping the reaction after reacting for 5min to obtain a caprolactam-sulfuric acid phase. The caprolactam-sulfuric acid phase is placed in 20kg of saturated ammonium sulfate aqueous solution, the temperature is kept at 45 ℃, stirring is started, ammonia gas is gradually introduced into the solution, the liquid is divided into three phases after the introduction, and the pH value of the lower aqueous phase is 6.1. The upper caprolactam phase was taken in a total of 30.1kg, placed in 30kg of benzene, kept at 45℃and stirred until extraction was completed. Taking 50.6kg 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 extraction is completed to obtain an aqueous solution of caprolactam.
According to analysis, the conversion rate of cyclohexanone oxime is 100%, the selectivity of caprolactam is 69.8%, the yield of caprolactam after neutralization crystallization-extraction treatment is 12.7kg, the yield is 63.4%, the amount of byproduct ammonium sulfate is 17.2kg, and the byproduct ammonium sulfate is 1.35kg per kg of caprolactam.
Description: in comparative example 1, no solvent was used, more sulfuric acid was added, and the results showed high yield, but more ammonium sulfate was by-produced, and in comparative example 2, no solvent was used, less sulfuric acid was added, and the results showed less sulfuric acid was by-produced, but low yield. It is said that the yield and by-product are difficult to be completed without adding solvent.
Comparative example 3
20kg of cyclohexanone oxime was placed in 50kg of trichloroethylene, stirred until it was completely dissolved, preheated to 150℃and 13kg of 10% strength fuming sulfuric acid 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 a solution containing caprolactam-sulfate. At this time, the trichloroethylene can dissolve part of caprolactam-sulfate, so that the product is separated into two phases, and caprolactam-sulfate is dissolved in both phases.
The product solution was added to 97kg of saturated aqueous ammonium sulphate solution, maintaining the temperature at 50 ℃. Stirring is started, ammonia gas is gradually introduced into the mixture, the liquid is divided into three phases after the introduction, the lower layer is ammonium sulfate sediment, the pH value of the water phase in the middle layer is 6.30, and the upper layer is an organic solution phase containing caprolactam. The organic solution phase of the upper layer contains caprolactam-sulfate which is difficult to remove by analysis.
96.8kg of the upper caprolactam phase was taken and placed in a flash tank, the temperature was kept at 50℃and the absolute pressure was 101kPa, and after flash evaporation, trichloroethylene was removed to obtain 32.6kg of an aqueous caprolactam solution. An aqueous solution of caprolactam was placed in 20kg of benzene, kept at 45℃and stirred until extraction was completed. The upper caprolactam-benzene phase was taken and put in 20kg of water at 25℃until extraction was completed to obtain an aqueous caprolactam solution, which was 38.8kg in total.
According to analysis, the conversion rate of cyclohexanone oxime is 100%, the selectivity of caprolactam is 99.7%, part of caprolactam is lost along with the solvent because caprolactam-sulfate is not removed, the yield of caprolactam is 18.2kg, the yield is 91.0%, the amount of byproduct ammonium sulfate is 16.8kg, and the byproduct ammonium sulfate is 0.92kg per kg of caprolactam. Although the byproduct ammonium sulfate is reduced, the caprolactam yield is lower. And the solvent is polluted, which is difficult to be repeatedly beneficial.
The foregoing description of the preferred embodiments of the invention is not intended to be limiting, but rather is intended to cover all modifications, equivalents, alternatives, and improvements that fall within the spirit and scope of the invention.
Claims (18)
1. A method for synthesizing caprolactam by Beckmann rearrangement reaction, which is characterized by comprising the following steps:
(1) Placing cyclohexanone oxime in a solvent, and stirring until the cyclohexanone oxime is dissolved;
(2) Placing fuming sulfuric acid in 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 a two-phase mixed solution, stirring until the two-phase mixed solution is uniformly mixed, and preserving heat to obtain caprolactam-sulfuric acid solution;
(4) Injecting the caprolactam-sulfuric acid solution obtained in the step (3) into a saturated ammonium sulfate aqueous solution, introducing a sufficient amount of ammonia gas to neutrality, completely separating the solvent, the caprolactam and the ammonium sulfate aqueous solution through salting out, wherein the separated liquid is three phases, namely a caprolactam solvent phase, a saturated ammonium sulfate aqueous solution phase and ammonium sulfate crystallization;
(5) Flashing the caprolactam phase obtained in the step (4) to remove a solvent in the caprolactam phase to obtain an aqueous solution of caprolactam;
(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) and the solvent in the step (2) are the same, and the selected solvent is one or more of 1, 2-tetrachloroethane, 1-difluoro-1, 2-dichloroethane, acetonitrile, N-dimethylformamide, acetone, butanone, dioxane and tert-butanol.
2. The method for synthesizing caprolactam by beckmann rearrangement according to claim 1, wherein: in the step (1), the mass concentration of the cyclohexanone oxime is 5 to 50 weight percent.
3. The method for synthesizing caprolactam by beckmann rearrangement according to claim 2, wherein: in the step (1), the mass concentration of the cyclohexanone oxime is 25-40 wt%.
4. The method for synthesizing caprolactam by beckmann rearrangement according to claim 1, wherein: in the step (2), SO in fuming sulfuric acid is used 3 The concentration is 3-30%, and the concentration of fuming sulfuric acid in the solvent is 30-80% by weight.
5. The method for synthesizing caprolactam by Beckmann rearrangement according to claim 4, wherein: in the step (2), SO in fuming sulfuric acid is used 3 The concentration is 12-20%, and the concentration of fuming sulfuric acid in the solvent is 40-50 wt%.
6. The method for synthesizing caprolactam by beckmann rearrangement according to claim 1, wherein: in the step (3), the preheating temperature of the cyclohexanone oxime solution is 50-270 ℃, and the preheating temperature of the fuming sulfuric acid solution is 50-270 ℃.
7. The method for synthesizing caprolactam by Beckmann rearrangement according to claim 6, wherein: in the step (3), the preheating temperature of the cyclohexanone oxime solution is 80-180 ℃, and the preheating temperature of the fuming sulfuric acid solution is 80-180 ℃.
8. The method for synthesizing caprolactam by beckmann rearrangement according to claim 1, wherein: in the step (3), the mass ratio of the cyclohexanone oxime to the fuming sulfuric acid is 0.5-4.
9. The method for synthesizing caprolactam by beckmann rearrangement according to claim 8, wherein: in the step (3), the mass ratio of the cyclohexanone oxime to the fuming sulfuric acid is 1.2-2.2.
10. The method for synthesizing caprolactam by beckmann rearrangement according to claim 1, wherein: in the step (3), the reaction temperature is 50-270 ℃ and the reaction time is 0.5-30 min.
11. The method for synthesizing caprolactam by beckmann rearrangement according to claim 10, wherein: in the step (3), the reaction temperature is 80-180 ℃ and the reaction time is 5-15 min.
12. The method for synthesizing caprolactam by beckmann rearrangement 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 the water phase after ammonia gas is introduced is 4-10, and the neutralization crystallization reaction temperature is 30-70 ℃.
13. The method for synthesizing caprolactam by beckmann rearrangement according to claim 12, wherein: in the step (4), the neutralization crystallization reaction temperature is 40-50 ℃.
14. The method for synthesizing caprolactam by 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 solvent content in the flash evaporated caprolactam solution is less than 0.01%.
15. The method for synthesizing caprolactam by 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, and the treatment temperature is 30-70 ℃.
16. The method for synthesizing caprolactam by beckmann rearrangement according to claim 15, wherein: in the step (6), the mass ratio of the caprolactam phase to the benzene is 1-2, and the treatment temperature is 40-50 ℃.
17. The method for synthesizing caprolactam by beckmann rearrangement according to claim 1, wherein: in the step (7), the mass ratio of caprolactam-benzene phase to water is 1-5, and the extraction temperature is 20-40 ℃.
18. The method for synthesizing caprolactam by beckmann rearrangement of claim 17, wherein: in the step (7), the mass ratio of the caprolactam-benzene phase to the water is 2-3.
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|---|---|---|---|---|
| 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 |
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| 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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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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