CN115819344A - Process method for producing caprolactam and coproducing sulfuric ester by liquid phase Beckmann rearrangement - Google Patents
Process method for producing caprolactam and coproducing sulfuric ester by liquid phase Beckmann rearrangement Download PDFInfo
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- JBKVHLHDHHXQEQ-UHFFFAOYSA-N epsilon-caprolactam Chemical compound O=C1CCCCCN1 JBKVHLHDHHXQEQ-UHFFFAOYSA-N 0.000 title claims abstract description 160
- 238000000034 method Methods 0.000 title claims abstract description 40
- 238000006237 Beckmann rearrangement reaction Methods 0.000 title claims abstract description 16
- 239000007791 liquid phase Substances 0.000 title claims abstract description 16
- 150000002148 esters Chemical class 0.000 title claims abstract description 14
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 10
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims abstract description 79
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims abstract description 74
- RTZKZFJDLAIYFH-UHFFFAOYSA-N Diethyl ether Chemical compound CCOCC RTZKZFJDLAIYFH-UHFFFAOYSA-N 0.000 claims abstract description 53
- 238000000605 extraction Methods 0.000 claims abstract description 49
- DENRZWYUOJLTMF-UHFFFAOYSA-N diethyl sulfate Chemical compound CCOS(=O)(=O)OCC DENRZWYUOJLTMF-UHFFFAOYSA-N 0.000 claims abstract description 41
- 229940008406 diethyl sulfate Drugs 0.000 claims abstract description 41
- KIWBPDUYBMNFTB-UHFFFAOYSA-N Ethyl hydrogen sulfate Chemical compound CCOS(O)(=O)=O KIWBPDUYBMNFTB-UHFFFAOYSA-N 0.000 claims abstract description 39
- 239000007788 liquid Substances 0.000 claims abstract description 34
- 239000000047 product Substances 0.000 claims abstract description 34
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 34
- 239000006227 byproduct Substances 0.000 claims abstract description 33
- 238000006460 hydrolysis reaction Methods 0.000 claims abstract description 33
- 239000012071 phase Substances 0.000 claims abstract description 33
- 238000005886 esterification reaction Methods 0.000 claims abstract description 31
- 239000012043 crude product Substances 0.000 claims abstract description 18
- 239000000284 extract Substances 0.000 claims abstract description 17
- 230000032050 esterification Effects 0.000 claims abstract description 15
- 239000007795 chemical reaction product Substances 0.000 claims abstract description 10
- 239000003795 chemical substances by application Substances 0.000 claims abstract description 10
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 claims abstract description 9
- 230000007062 hydrolysis Effects 0.000 claims abstract description 9
- 238000007670 refining Methods 0.000 claims abstract description 9
- 238000003756 stirring Methods 0.000 claims abstract description 8
- 238000004064 recycling Methods 0.000 claims description 29
- 235000019441 ethanol Nutrition 0.000 claims description 22
- VEZUQRBDRNJBJY-UHFFFAOYSA-N cyclohexanone oxime Chemical compound ON=C1CCCCC1 VEZUQRBDRNJBJY-UHFFFAOYSA-N 0.000 claims description 18
- 230000035484 reaction time Effects 0.000 claims description 13
- 239000011259 mixed solution Substances 0.000 claims description 9
- 230000008707 rearrangement Effects 0.000 claims description 4
- 239000000126 substance Substances 0.000 abstract description 2
- 238000004458 analytical method Methods 0.000 description 5
- 238000004817 gas chromatography Methods 0.000 description 5
- BFNBIHQBYMNNAN-UHFFFAOYSA-N ammonium sulfate Chemical compound N.N.OS(O)(=O)=O BFNBIHQBYMNNAN-UHFFFAOYSA-N 0.000 description 4
- 229910052921 ammonium sulfate Inorganic materials 0.000 description 4
- 235000011130 ammonium sulphate Nutrition 0.000 description 4
- JHIVVAPYMSGYDF-UHFFFAOYSA-N cyclohexanone Chemical compound O=C1CCCCC1 JHIVVAPYMSGYDF-UHFFFAOYSA-N 0.000 description 4
- YXFVVABEGXRONW-UHFFFAOYSA-N Toluene Chemical compound CC1=CC=CC=C1 YXFVVABEGXRONW-UHFFFAOYSA-N 0.000 description 3
- 238000006243 chemical reaction Methods 0.000 description 2
- XDTMQSROBMDMFD-UHFFFAOYSA-N Cyclohexane Chemical compound C1CCCCC1 XDTMQSROBMDMFD-UHFFFAOYSA-N 0.000 description 1
- 229920002292 Nylon 6 Polymers 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
- 238000007796 conventional method Methods 0.000 description 1
- HYBIIGFUKKOJJM-UHFFFAOYSA-N cyclohexanone;hydroxylamine Chemical compound ON.O=C1CCCCC1 HYBIIGFUKKOJJM-UHFFFAOYSA-N 0.000 description 1
- 239000000835 fiber Substances 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 229920006122 polyamide resin Polymers 0.000 description 1
- 238000006116 polymerization reaction Methods 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- -1 sulfuric acid ester Chemical class 0.000 description 1
- 238000010998 test method Methods 0.000 description 1
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Classifications
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- 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
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- Other In-Based Heterocyclic Compounds (AREA)
Abstract
The invention belongs to the technical field of chemical product production, and discloses a process method for producing caprolactam and simultaneously producing sulfuric ester as a byproduct by liquid phase Beckmann rearrangement, which comprises the steps of adding heavy discharge liquid of a caprolactam reactor, absolute ethyl alcohol and water into an esterification reactor, fully stirring to perform esterification reaction, firstly performing primary extraction on obtained mixed liquid by taking diethyl ether as an extractant, separating a caprolactam crude product from an extract phase of the primary extraction, and refining the caprolactam crude product to obtain a main product caprolactam; performing secondary extraction on the raffinate phase of the primary extraction by using water as an extracting agent, separating a crude diethyl sulfate product from the raffinate phase of the secondary extraction, and refining the crude diethyl sulfate product to obtain a byproduct diethyl sulfate; the extract phase of the second-stage extraction enters a sulfate hydrolysis reactor to carry out hydrolysis reaction, and byproducts of the ethyl bisulfate and dilute sulfuric acid are separated from the hydrolysis reaction product. The process of the invention can produce high-value sulfuric ester as a byproduct, and has important economic and social benefits.
Description
Technical Field
The invention belongs to the technical field of chemical product production, and relates to a process method for producing caprolactam and coproducing sulfuric ester by liquid phase Beckmann rearrangement.
Background
Caprolactam is an important organic chemical raw material, which is mainly used for producing polyamide-6 fibers, polyamide resins and films through polymerization. The caprolactam production process mainly comprises the following steps: cyclohexanone-hydroxylamine process, toluene process, cyclohexane photonitrosation process and cyclohexanone ammoximation process. The cyclohexanone oxime liquid phase Beckmann rearrangement (cyclohexanone ammoximation method) is the mainstream process for producing caprolactam, but a large amount of low-value ammonium sulfate products are by-produced in the catalytic reaction process. Therefore, the research on the green process for producing caprolactam by rearrangement without ammonium sulfate is carried out, and the additional value of byproducts is improved, so that the method has important significance.
Disclosure of Invention
The invention aims to provide a process method for producing caprolactam and simultaneously producing sulfuric ester by liquid phase Beckmann rearrangement, which solves the problem of low-value ammonium sulfate byproduct in the prior art, obtains high-purity caprolactam, produces a small amount of high-value sulfuric ester (diethyl sulfate and ethyl hydrogen sulfate) as a byproduct, recycles ethanol, concentrated sulfuric acid and water, and has important economic and social benefits.
In order to achieve the purpose, the invention adopts the following technical scheme:
the invention provides a process method for producing caprolactam and simultaneously producing sulfuric ester as a byproduct by liquid-phase Beckmann rearrangement, which comprises the following steps of adding cyclohexanone oxime and oleum into a caprolactam reactor to generate liquid-phase Beckmann rearrangement reaction:
step 1: adding the heavy discharge liquid of a caprolactam reactor, absolute ethyl alcohol and water into an esterification reactor together, and fully stirring to ensure that sulfuric acid in the rearrangement liquid and the ethyl alcohol are subjected to esterification reaction to obtain a mixed liquid;
step 2: the mixed solution obtained in the step 1 enters a first extractor, first-stage extraction is carried out by taking diethyl ether as an extracting agent, an extraction phase of the first-stage extraction enters a first separator to separate a crude product of caprolactam, and the crude product of caprolactam is refined to obtain a main product of caprolactam; the raffinate phase of the first-stage extraction enters a second extractor, then water is used as an extracting agent for second-stage extraction, the raffinate phase of the second-stage extraction enters a second separator for separating a crude diethyl sulfate product, and the crude diethyl sulfate product is refined to obtain a byproduct diethyl sulfate;
and step 3: and (3) allowing an extract phase of the second-stage extraction to enter a sulfate hydrolysis reactor to perform hydrolysis reaction, allowing a hydrolysis reaction product to enter a third separator to separate out by-products of ethyl bisulfate and dilute sulfuric acid, and refining the dilute sulfuric acid and then returning the refined dilute sulfuric acid to the caprolactam reactor for recycling.
In one technical scheme, the temperature of the esterification reaction in the step 1 is 30 to 80 ℃, and the reaction time is 1 to 4 hours.
In one technical scheme, the molar ratio of concentrated sulfuric acid to absolute ethyl alcohol in the re-draining liquid in the step 1 is 1:2 to 8.
In one technical scheme, the temperature of the hydrolysis reaction in the step 3 is 75 to 105 ℃, and the reaction time is 0.1 to 2h.
In a technical scheme, diethyl ether is obtained while the first separator separates out a caprolactam crude product in the step 2, and the diethyl ether is returned to the first extractor for recycling.
In a technical scheme, the ethanol obtained in the step 2 when the caprolactam crude product is refined is returned to the esterification reactor for recycling.
In a technical scheme, water is obtained while byproducts of the ethyl bisulfate and the concentrated sulfuric acid are separated by the third separator in the step 3, and the water is returned to the second extractor for recycling.
Compared with the prior art, the invention has the beneficial effects that:
the invention firstly carries out esterification reaction on the heavy discharge liquid of cyclohexanone-oxime, water and ethanol, and extracts and separates the mixed solution of the reaction products step by step according to the component characteristics of the mixed solution of the esterification reaction products to obtain the main product of caprolactam and the byproduct of diethyl sulfate, and meanwhile, the extractant of diethyl ether is recovered. In addition, the extract phase rich in sulfate is subjected to hydrolysis reaction, byproducts of the ethyl bisulfate and dilute sulfuric acid are separated from hydrolysis products, meanwhile, process water is recovered, and the dilute sulfuric acid is returned to the caprolactam reactor for recycling after being refined. The process method solves the problem of low-value ammonium sulfate byproduct in the prior art, obtains high-purity caprolactam, produces a small amount of high-value sulfuric acid ester (diethyl sulfate and ethyl bisulfate) as a byproduct, recycles ethanol, concentrated sulfuric acid and water, and has important economic and social benefits.
Drawings
FIG. 1 is a flow chart of the process of the present invention.
Detailed Description
The following examples are intended to illustrate the invention, but are not intended to limit the scope of the invention. Unless otherwise specified, the technical means used in the examples are conventional means well known to those skilled in the art. The test methods in the following examples are conventional methods unless otherwise specified.
Example one
Referring to the process flow shown in fig. 1, the process for producing caprolactam and simultaneously producing sulfuric ester as a byproduct by liquid phase beckmann rearrangement in the embodiment includes the following steps:
adding cyclohexanone oxime and oleum in a mass ratio of 1;
adding the heavy discharge liquid of a caprolactam reactor, absolute ethyl alcohol and water into an esterification reactor, and fully stirring to ensure that sulfuric acid and ethanol in the rearrangement liquid have esterification reaction (see a reaction formula (1)), wherein the molar ratio of concentrated sulfuric acid to absolute ethyl alcohol in the heavy discharge liquid is 1;
2H 2 SO 4 +3CH 3 CH 2 OH=CH 3 CH 2 OHSO 3 +(CH 3 CH 2 O) 2 SO 2 +3H 2 O（1）；
the mixed solution enters a first extractor, first-stage extraction is carried out by taking ether as an extractant, an extract phase of the first-stage extraction enters a first separator to separate a caprolactam crude product and ether, the ether returns to the first extractor for recycling, the caprolactam crude product is refined to obtain a main product of caprolactam and ethanol, and the ethanol returns to an esterification reactor for recycling; the raffinate phase of the first-stage extraction enters a second extractor, then water is used as an extracting agent for second-stage extraction, the raffinate phase of the second-stage extraction enters a second separator for separating a crude diethyl sulfate product, and the crude diethyl sulfate product is refined to obtain a byproduct diethyl sulfate;
and (3) allowing the extract phase of the second-stage extraction to enter a sulfate hydrolysis reactor to perform hydrolysis reaction (see a reaction formula (2)), wherein the temperature of the hydrolysis reaction is 105 ℃, the reaction time is 1h, a hydrolysis reaction product enters a third separator to separate out by-products of ethyl bisulfate, dilute sulfuric acid and water, the dilute sulfuric acid is refined to obtain concentrated sulfuric acid, and the concentrated sulfuric acid is returned to the caprolactam reactor for recycling, and the water is returned to the second extractor for recycling.
CH 3 CH 2 OHSO 3 +H 2 O=H 2 SO 4 +CH 3 CH 2 OH（2）。
The three products of caprolactam, ethyl hydrogen sulfate and diethyl sulfate are measured by gas chromatography analysis: the caprolactam content was 99.2%, the ethyl hydrogen sulfate content was 98.5%, and the diethyl sulfate content was 99.0%.
Example two
Referring to the process flow shown in fig. 1, the process for producing caprolactam and simultaneously producing sulfuric ester as a byproduct by liquid phase beckmann rearrangement in the embodiment includes the following steps:
adding cyclohexanone oxime and oleum in a mass ratio of 1:1.2 into a caprolactam reactor to perform liquid phase Beckmann rearrangement reaction;
adding the re-discharged liquid of a caprolactam reactor, absolute ethyl alcohol and water into an esterification reactor, and fully stirring to ensure that sulfuric acid and ethanol in the rearranged liquid have esterification reaction, wherein the molar ratio of concentrated sulfuric acid to the absolute ethyl alcohol in the re-discharged liquid is 1, the esterification reaction temperature is 40 ℃, the reaction time is 1.5 hours, so as to obtain a mixed liquid, wherein the mass fraction of caprolactam in the mixed liquid is 69%, the mass fraction of ethyl hydrogen sulfate is 24%, and the mass fraction of diethyl sulfate is 6%;
the mixed solution enters a first extractor, first-stage extraction is carried out by taking ether as an extractant, an extract phase of the first-stage extraction enters a first separator to separate a caprolactam crude product and ether, the ether returns to the first extractor for recycling, the caprolactam crude product is refined to obtain a main product of caprolactam and ethanol, and the ethanol returns to an esterification reactor for recycling; the raffinate phase of the first-stage extraction enters a second extractor, then water is used as an extracting agent for second-stage extraction, the raffinate phase of the second-stage extraction enters a second separator for separating a crude diethyl sulfate product, and the crude diethyl sulfate product is refined to obtain a byproduct diethyl sulfate;
and (3) allowing an extract phase of the second-stage extraction to enter a sulfate hydrolysis reactor for hydrolysis reaction, allowing a hydrolysis reaction product to enter a third separator to separate out by-products of ethyl bisulfate, dilute sulfuric acid and water, refining the dilute sulfuric acid to obtain concentrated sulfuric acid, returning the concentrated sulfuric acid to a caprolactam reactor for recycling, and returning the water to a second extractor for recycling, wherein the temperature of the hydrolysis reaction is 110 ℃ and the reaction time is 0.5 h.
The three products of caprolactam, ethyl hydrogen sulfate and diethyl sulfate are measured by gas chromatography analysis: the caprolactam content was 99.1%, the ethyl hydrogen sulfate content was 98.8%, and the diethyl sulfate content was 99.2%.
EXAMPLE III
Referring to the process flow shown in fig. 1, the process for producing caprolactam and simultaneously producing sulfuric ester as a byproduct by liquid phase beckmann rearrangement in the embodiment includes the following steps:
adding cyclohexanone oxime and oleum in a mass ratio of 1;
adding the re-discharged liquid of a caprolactam reactor, absolute ethyl alcohol and water into an esterification reactor, and fully stirring to ensure that sulfuric acid and ethanol in the rearranged liquid have esterification reaction, wherein the molar ratio of concentrated sulfuric acid to the absolute ethyl alcohol in the re-discharged liquid is 1, the esterification reaction temperature is 50 ℃, the reaction time is 1h, so as to obtain a mixed liquid, and the mixed liquid contains 58 mass percent of caprolactam, 30 mass percent of ethyl bisulfate and 10 mass percent of diethyl sulfate;
the mixed solution enters a first extractor, first-stage extraction is carried out by taking ether as an extractant, an extract phase of the first-stage extraction enters a first separator to separate a caprolactam crude product and ether, the ether returns to the first extractor for recycling, the caprolactam crude product is refined to obtain a main product of caprolactam and ethanol, and the ethanol returns to an esterification reactor for recycling; the raffinate phase of the first-stage extraction enters a second extractor, then water is used as an extracting agent for second-stage extraction, the raffinate phase of the second-stage extraction enters a second separator for separating a crude diethyl sulfate product, and the crude diethyl sulfate product is refined to obtain a byproduct diethyl sulfate;
and (3) allowing an extract phase of the second-stage extraction to enter a sulfate hydrolysis reactor for hydrolysis reaction, allowing the temperature of the hydrolysis reaction to be 105 ℃ and the reaction time to be 2 hours, allowing a hydrolysis reaction product to enter a third separator to separate out by-products of ethyl bisulfate, dilute sulfuric acid and water, refining the dilute sulfuric acid to obtain concentrated sulfuric acid, and returning the concentrated sulfuric acid to a caprolactam reactor for recycling, and returning the water to the second extractor for recycling.
The three products of caprolactam, ethyl hydrogen sulfate and diethyl sulfate are measured by gas chromatography analysis: the caprolactam content was 99.5%, the ethyl hydrogen sulfate content was 99.0%, and the diethyl sulfate content was 99.1%.
Example four
Referring to the process flow shown in fig. 1, the process for producing caprolactam and simultaneously producing sulfuric ester as a byproduct by liquid phase beckmann rearrangement in the embodiment includes the following steps:
adding cyclohexanone oxime and oleum in a mass ratio of 1;
adding the re-discharged liquid of a caprolactam reactor, absolute ethyl alcohol and water into an esterification reactor, and fully stirring to ensure that sulfuric acid and ethanol in the rearranged liquid have esterification reaction, wherein the molar ratio of concentrated sulfuric acid to the absolute ethyl alcohol in the re-discharged liquid is 1, the esterification reaction temperature is 30 ℃, the reaction time is 1h, so as to obtain a mixed liquid, wherein the mass fraction of caprolactam in the mixed liquid is 70%, the mass fraction of ethyl bisulfate is 20%, and the mass fraction of diethyl sulfate is 2%;
the mixed solution enters a first extractor, first-stage extraction is carried out by taking ether as an extractant, an extract phase of the first-stage extraction enters a first separator to separate a caprolactam crude product and ether, the ether returns to the first extractor for recycling, the caprolactam crude product is refined to obtain a main product of caprolactam and ethanol, and the ethanol returns to an esterification reactor for recycling; the raffinate phase of the first-stage extraction enters a second extractor, then water is used as an extracting agent for second-stage extraction, the raffinate phase of the second-stage extraction enters a second separator for separating a crude diethyl sulfate product, and the crude diethyl sulfate product is refined to obtain a byproduct diethyl sulfate;
and (3) allowing the extract phase of the second-stage extraction to enter a sulfate hydrolysis reactor for hydrolysis reaction, wherein the temperature of the hydrolysis reaction is 90 ℃, the reaction time is 0.1h, allowing the hydrolysis reaction product to enter a third separator to separate out by-products of ethyl bisulfate, dilute sulfuric acid and water, refining the dilute sulfuric acid to obtain concentrated sulfuric acid, returning the concentrated sulfuric acid to a caprolactam reactor for recycling, and returning the water to a second extractor for recycling.
The three products of caprolactam, ethyl hydrogen sulfate and diethyl sulfate are measured by gas chromatography analysis: the caprolactam content was 99.1%, the ethyl hydrogen sulfate content was 99.2%, and the diethyl sulfate content was 99.5%.
EXAMPLE five
Referring to the process flow shown in fig. 1, the process for producing caprolactam and simultaneously producing sulfuric ester as a byproduct by liquid phase beckmann rearrangement in the embodiment includes the following steps:
adding cyclohexanone oxime and oleum in a mass ratio of 1;
adding the re-discharged liquid of a caprolactam reactor, absolute ethyl alcohol and water into an esterification reactor, and fully stirring to ensure that sulfuric acid and ethanol in the rearranged liquid have esterification reaction, wherein the molar ratio of concentrated sulfuric acid to the absolute ethyl alcohol in the re-discharged liquid is 1, the esterification reaction temperature is 50 ℃, the reaction time is 4 hours, so as to obtain a mixed liquid, wherein the mass fraction of caprolactam in the mixed liquid is 60%, the mass fraction of ethyl bisulfate is 30%, and the mass fraction of diethyl sulfate is 2%;
the mixed solution enters a first extractor, first-stage extraction is carried out by taking ether as an extractant, an extract phase of the first-stage extraction enters a first separator to separate a caprolactam crude product and ether, the ether returns to the first extractor for recycling, the caprolactam crude product is refined to obtain a main product of caprolactam and ethanol, and the ethanol returns to an esterification reactor for recycling; the raffinate phase of the first-stage extraction enters a second extractor, then water is used as an extracting agent for second-stage extraction, the raffinate phase of the second-stage extraction enters a second separator for separating a crude diethyl sulfate product, and the crude diethyl sulfate product is refined to obtain a byproduct diethyl sulfate;
and (3) allowing an extract phase of the second-stage extraction to enter a sulfate hydrolysis reactor for hydrolysis reaction, allowing the temperature of the hydrolysis reaction to be 105 ℃ and the reaction time to be 2 hours, allowing a hydrolysis reaction product to enter a third separator to separate out by-products of ethyl bisulfate, dilute sulfuric acid and water, refining the dilute sulfuric acid to obtain concentrated sulfuric acid, and returning the concentrated sulfuric acid to a caprolactam reactor for recycling, and returning the water to the second extractor for recycling.
The three products of caprolactam, ethyl hydrogen sulfate and diethyl sulfate are measured by gas chromatography analysis: the caprolactam content was 99.3%, the ethyl hydrogen sulfate content was 98.9%, and the diethyl sulfate content was 99.0%.
The above-mentioned embodiments are only preferred embodiments of the present invention, and are not intended to limit the scope of the present invention, and it is obvious to those skilled in the art that other embodiments can be easily made by replacing or changing the technical contents disclosed in the present specification, and therefore, all changes and modifications made on the principle of the present invention should be included in the claims of the present invention.
Claims (7)
1. A process method for producing caprolactam and coproducing sulfuric ester by liquid phase Beckmann rearrangement is characterized in that cyclohexanone oxime and oleum are added into a caprolactam reactor to generate a liquid phase Beckmann rearrangement reaction, and the process method is characterized by also comprising the following steps:
step 1: adding the heavy discharge liquid of a caprolactam reactor, absolute ethyl alcohol and water into an esterification reactor together, and fully stirring to ensure that sulfuric acid in the rearrangement liquid and the ethyl alcohol are subjected to esterification reaction to obtain a mixed liquid;
step 2: the mixed solution obtained in the step 1 enters a first extractor, first-stage extraction is carried out by taking ether as an extracting agent, an extract phase of the first-stage extraction enters a first separator to separate a caprolactam crude product, and the caprolactam crude product is refined to obtain a main product caprolactam; the raffinate phase of the first-stage extraction enters a second extractor, then water is used as an extracting agent for second-stage extraction, the raffinate phase of the second-stage extraction enters a second separator for separating a crude diethyl sulfate product, and the crude diethyl sulfate product is refined to obtain a byproduct diethyl sulfate;
and 3, step 3: and (3) allowing an extract phase of the secondary extraction to enter a sulfate hydrolysis reactor to perform hydrolysis reaction, allowing a hydrolysis reaction product to enter a third separator to separate out by-products of ethyl bisulfate and dilute sulfuric acid, and refining the dilute sulfuric acid and then returning the refined dilute sulfuric acid to a caprolactam reactor for recycling.
2. The process according to claim 1, wherein the esterification reaction in step 1 is carried out at a temperature of 30 to 80 ℃ for a reaction time of 1 to 4 hours.
3. The process of claim 1, wherein the molar ratio of concentrated sulfuric acid to absolute ethanol in the heavy liquid effluent in step 1 is 1:2 to 8.
4. The process method as claimed in claim 1, wherein the temperature of the hydrolysis reaction in the step 3 is 75 to 105 ℃ and the reaction time is 0.1 to 2h.
5. The process of claim 1, wherein in step 2, diethyl ether is obtained while the crude caprolactam is separated in the first separator, and the diethyl ether is returned to the first extractor for recycling.
6. The process of claim 1, wherein the ethanol obtained in step 2 when refining the crude caprolactam is returned to the esterification reactor for recycling.
7. The process of claim 1, wherein in step 3, the third separator separates out the byproducts of the ethyl bisulfate and the concentrated sulfuric acid and simultaneously obtains water, and the water is returned to the second extractor for recycling.
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| 许开天等: "酒精制品的生产与配方", 30 November 1995, 中国轻工业出版社, pages: 141 * |
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