A method for co-producing caprolactam and hydroxylamine sulfate

Abstract

A method for co-producing caprolactam and hydroxylamine sulfate comprises: (1) ammoximation reaction: ketone, ammonia and hydrogen peroxide are reacted at a certain temperature under the action of a titanium silicon catalyst to produce an oxime solution; (2) hydrolysis reaction: caprolactam sulfate is added with an appropriate amount of desalted water, stirred, and the hydrolysis temperature is controlled to carry out a hydrolysis reaction to obtain a hydrolysis reactant caprolactam sulfuric acid solution; (3) co-production reaction of caprolactam and hydroxylamine sulfate: oxime solution is added to step (3), and the reaction is carried out at a certain temperature and pressure to obtain caprolactam and hydroxylamine sulfate solution; (4) physical separation: the reactants in step (3) are separated into layers, the upper layer is a light phase, which is an organic solvent containing caprolactam, and the lower layer is a heavy phase, which is an aqueous phase containing hydroxylamine salt; (5) the organic solvent containing ketone is returned to step (1) for ammoximation reaction, or after the solvent is removed, it is returned to step (1) for ammoximation reaction; the lower layer is subjected to sedimentation, centrifugal separation, and drying to obtain a crude caprolactam solution and hydroxylamine sulfate salt. The invention has the advantages of simple process, combining the production of caprolactam with the production of hydroxylamine salt, reducing the by-product of ammonium sulfate, and producing caprolactam and hydroxylamine salt at the same time.

Description

Technical Field

[0001] The invention relates to a method for co-producing caprolactam and hydroxylamine sulfate by using caprolactam transposition ester and alkanoxime solution. Background Art

[0002] Caprolactam, scientifically known as ε-caprolactam, has a molecular formula of C6H11NO, a molecular weight of 113.16, and a structural formula of [unclear]. It appears as a white powder or crystal with an oily feel, a melting point of 69.3°C, and a boiling point of 262.5°C. Caprolactam is an important organic chemical raw material. Its primary use is in the polymerization of polyamide chips (commonly called nylon-6 chips, or polyamide-6 chips), which can be further processed into nylon fibers, engineering plastics, and plastic films. Nylon-6 chips have varying application areas depending on their quality and performance.

[0003] Caprolactam sulfate produced by various industrial processes is almost always neutralized with ammonia to produce caprolactam and ammonium sulfate. This process has long been used in caprolactam production. Its advantages lie in its maturity, acid-base neutralization to form salts, and the ease of caprolactam separation. However, its main disadvantages are the large consumption of highly economically valuable ammonia and oleum, and the production of less economically valuable ammonium sulfate as a byproduct. For every ton of caprolactam produced, 1.6 to 1.8 tons of ammonium sulfate are produced, with some producing as much as 4.5 tons. Ammonium sulfate is a fertilizer sold below cost, and large amounts of it increase costs. Improving the production process and reducing ammonium sulfate production have been major challenges in caprolactam production. Furthermore, as an inefficient and acidic nitrogen-containing fertilizer, ammonium sulfate is detrimental to soil quality and has historically been unpopular in agriculture. The high levels of ammonium sulfate produced as a byproduct also pose challenges in sales.

[0004] Hydroxylamine sulfate, also known as hydroxylamine sulfate or hydroxylamine sulfate, is an important intermediate with a wide range of applications in pharmaceuticals, pesticides, and organic synthesis. Examples include hydroxylamine-O-sulfonic acid, an intermediate in the synthesis of the drug indapamide; acetaldehyde oxime, an intermediate in the synthesis of the pesticide methomyl; and cyclohexanone oxime, an intermediate in the synthesis of caprolactam. Hydroxylamine sulfate is also widely used in the fragrance, dye, oil, photographic, and rubber industries.

[0005] Currently, solid hydroxylamine sulfate production is primarily concentrated in a few countries, such as Germany and Japan. In 2014, global solid hydroxylamine sulfate production capacity reached 57,000 tons, with Germany accounting for 43.9% and Japan second at 35.1%. China, despite its relatively late development, still accounts for 12.3% of the total. my country's research and development of hydroxylamine sulfate began relatively late, and currently primarily produces liquid hydroxylamine sulfate, typically for manufacturers' own use. The only solid hydroxylamine sulfate production enterprise in China is located in Zhejiang Province, with a production line capacity of 7,000 tons per year (accounting for one-eighth of the global total).

[0006] Prior art disclosed solid hydroxylamine sulfate synthesis routes and processes, both domestically and internationally, primarily include the nitromethane route, natural gas (methane) nitration route, acetone oxime route, disulfonate ammonium salt hydrolysis method, nitric oxide reduction method, and the production of hydroxylamine sulfate using trimethoprim wastewater. However, the nitromethane route has a low product yield, produces a wide variety of byproducts, and requires significant investment in separation equipment; the acetone oxime route has a complex process, requires a wide variety of raw materials, consumes a large amount of raw materials, and is costly; the disulfonate hydrolysis method, while mature, is only suitable for large-scale production in large factories and requires significant investment. The yields of the other process routes are relatively low. In summary, the high investment, wide variety of raw materials, high costs, low yield, and low product purity hinder the competitiveness of high-purity solid hydroxylamine sulfate. Summary of the Invention

[0007] The invention provides a method for co-producing caprolactam and hydroxylamine sulfate. The method has a simple process, combines caprolactam production with hydroxylamine salt production, reduces ammonium sulfate by-products, and produces caprolactam and hydroxylamine salt simultaneously.

[0008] The technical solution for achieving the purpose of the present invention is that a method for co-producing caprolactam and hydroxylamine sulfate comprises:

[0009] (1) Ammoximation reaction: ketone, ammonia, and hydrogen peroxide are reacted at a certain temperature under the action of titanium-silicon catalyst to produce oxime solution;

[0010] (2) Hydrolysis reaction: adding an appropriate amount of desalted water to caprolactam sulfate, stirring, controlling the hydrolysis temperature, and performing a hydrolysis reaction to obtain a hydrolysis reactant caprolactam sulfuric acid solution;

[0011] (3) Co-production of caprolactam and hydroxylamine sulfate: Add oxime solution to caprolactam sulfuric acid solution, and react at a certain temperature and pressure to obtain caprolactam and hydroxylamine sulfate solution;

[0012] (4) Physical separation: The reactants in step (3) are separated into layers, wherein the upper layer is a light phase containing an organic solvent containing ketone, and the lower layer is a heavy phase containing an aqueous phase containing hydroxylamine sulfate and caprolactam;

[0013] (5) the organic solvent containing ketone is returned to step (1) for ammoximation reaction, or after removing the solvent, the organic solvent is returned to step (1) for ammoximation reaction; the lower layer is subjected to sedimentation, centrifugal separation, and drying to obtain a crude caprolactam solution and hydroxylamine sulfate salt.

[0014] Furthermore, the ammoximation reaction in step (1) can be carried out by reacting the ketone with ammonia and hydrogen peroxide at a certain temperature and pressure under the catalytic action of a titanium-silicon catalyst using tert-butanol as a solvent, followed by extraction with toluene and distillation to obtain the oxime, or by reacting the ketone with ammonia and hydrogen peroxide at a certain temperature and pressure under the catalytic action of a titanium-silicon catalyst using water as a solvent to separate the oxime; or by reacting the ketone with ammonia and hydrogen peroxide at a certain temperature and pressure under the catalytic action of a titanium-silicon catalyst using a hydrocarbon as a solvent to separate the oxime.

[0015] Furthermore, the oxime solution in step (3) is an aromatic hydrocarbon oxime solvent obtained by dissolving pure oxime with an aromatic hydrocarbon solution, or an aromatic hydrocarbon organic solution of oxime obtained by extraction with an aromatic hydrocarbon organic solvent during the reaction process.

[0016] Furthermore, the aromatic hydrocarbon is an alkane / toluene organic solvent, and the alkane solvent is mainly one or more mixed solvents such as n-pentane, cyclopentane or cyclohexane.

[0017] Furthermore, in step (2), the caprolactam sulfate is obtained by a Beckmann rearrangement reaction of fuming sulfuric acid with molten pure cyclohexanone oxime, or a Beckmann rearrangement reaction of fuming sulfuric acid with a cyclohexanone oxime-alkane solution. Furthermore, in step (1), the mass ratio of oxime to solvent in the oxime solution is 1:(0.5-10).

[0018] Furthermore, the alkane is one or a mixed solvent of C5-C12 straight-chain alkanes, branched-chain alkanes, cycloalkanes, etc.

[0019] Furthermore, in step (2), the mass ratio of caprolactam sulfate to water is 1:2.5-1:0.3, the temperature is controlled between 0 and 120° C., the pressure is controlled between 50 K Pa and 0.2 MPa absolute pressure, and the hydrolysis time is 0.5-2 h.

[0020] Furthermore, in step (3), the reaction temperature is controlled between 0 and 120° C., the pressure is controlled between 50 KPa and 0.2 MPa absolute pressure, and the hydrolysis time is 0.5-6 h.

[0021] Furthermore, in the steps (4) and (5), the stratification is static stratification, the filtration is centrifugal filtration or filter press, and the drying is fluidized bed drying or rotary disk drying.

[0022] This patent has the following outstanding advantages:

[0023] 1. The present invention connects the ammoximation reaction / caprolactam rearrangement reaction / oxime hydrolysis reaction to produce hydroxylamine sulfate in series, solving the problem that the ammoximation reaction must have a high conversion rate of more than 99.9%. In this series reaction, the unconverted complete ketoxime solution can be directly deacidified and hydrolyzed to obtain hydroxylamine salt and ketone, thus solving the problem of requiring a high conversion rate for ammoximation.

[0024] 2. The hydrolysis of ketoxime to produce hydroxylamine salt requires a high conversion rate. In this cascade reaction, the conversion rate requirement is not very high. The unhydrolyzed oxime can be returned to the ammoximation reaction together with the generated ketone solution, solving the problem of requiring a high conversion rate for the separate oximation hydrolysis to produce hydroxylamine.

[0025] 3. Compared with the traditional caprolactam process, the process for separating caprolactam produced in the second step of the present invention eliminates the comprehensive reaction step with ammonia water, does not consume gaseous ammonia, and does not produce ammonium sulfate as a by-product.

[0026] 4. The third step of the present invention produces hydroxylamine sulfate. Compared with the traditional hydroxylamine process, no additional sulfuric acid is required, and caprolactam can be converted into caprolactam and hydroxylamine sulfate at the same time;

[0027] 5. The first step reaction product of the present invention serves as the raw material for the second step reaction and the raw material for the third step reaction. In the process of producing hydroxylamine, it is essentially the reaction of the first step reaction raw materials hydrogen peroxide and ammonia with the second step reaction raw material nicotinic acid. Compared with the traditional hydroxylamine salt process, there is no need to build a new first step production oximation device, thereby reducing production costs and simplifying the process. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 Flowchart of the present invention;

[0029] Figure 2 This is a preferred flow chart of the present invention. DETAILED DESCRIPTION

[0030] like Figure 1 A method for co-producing caprolactam and hydroxylamine sulfate comprises: (1) a heterogeneous ammoximation reaction: using water as a medium, reacting a ketone with ammonia and hydrogen peroxide in the presence of a catalyst, preferably cyclohexanone, to produce ketone oxime, and then extracting the oxime produced by the reaction with an alkane solvent to obtain an oxime solution, preferably, the mass ratio of oxime to solvent in the oxime solution is 1:(1.5-6);

[0031] (2) Hydrolysis reaction: adding an appropriate amount of desalted water to caprolactam sulfate to carry out hydrolysis reaction, stirring, controlling the temperature at 0-80°C, obtaining a hydrolysis reactant, obtaining a hydrolysis reactant caprolactam sulfuric acid solution, and obtaining caprolactam sulfate by rearrangement reaction, rearrangement reaction: sending the alkoxime solution to the rearrangement reactor to react with fuming sulfuric acid to produce caprolactam sulfate, preferably, the rearrangement reaction is a one-stage or multi-stage rearrangement; the rearrangement reaction equipment is a horizontal rearrangement, or a solvent rearrangement;

[0032] (3) Co-production reaction of caprolactam and hydroxylamine sulfate: adding the oxime solution obtained in step (1) to the hydrolysis reactant caprolactam sulfuric acid solution to react to obtain a reactant. Preferably, in step (3), the temperature is controlled between 0 and 120° C. and / or the pressure is controlled between 50 kPa and 0.2 MPa absolute pressure in step (3) and / or the reaction time in step (3) is 0.5-6 h;

[0033] The reactants include caprolactam and hydroxylamine sulfate.

[0034] like Figure 2 A method for co-producing caprolactam and hydroxylamine sulfate comprises: (1) a heterogeneous ammoximation reaction: using water as a medium, reacting a ketone with ammonia and hydrogen peroxide in the presence of a catalyst, preferably cyclohexanone, to produce ketoxime, and then extracting the oxime produced by the reaction with an alkane solvent to obtain an oxime solution, preferably, the mass ratio of oxime to solvent in the alkane oxime solution is 1:(1.5-6);

[0035] (2) Hydrolysis reaction: adding an appropriate amount of desalted water to caprolactam sulfate to carry out hydrolysis reaction, stirring, controlling the temperature at 0-80°C, obtaining a hydrolysis reactant, obtaining a hydrolysis reactant caprolactam sulfuric acid solution, and obtaining caprolactam sulfate by rearrangement reaction, rearrangement reaction: sending the alkoxime solution to the rearrangement reactor to react with fuming sulfuric acid to produce caprolactam sulfate, preferably, the rearrangement reaction is a one-stage or multi-stage rearrangement; the rearrangement reaction equipment is a horizontal rearrangement, or a solvent rearrangement;

[0036] (3) Co-production reaction of caprolactam and hydroxylamine sulfate: adding the oxime solution obtained in step (1) to the hydrolysis reactant caprolactam sulfuric acid solution to react to obtain a reactant. Preferably, the temperature in step (3) is controlled between 0 and 120° C. and / or the pressure in step (3) is controlled between 50 kPa and 0.2 MPa absolute pressure and / or the reaction time in step (3) is 0.5-6 h;

[0037] The reactants include caprolactam and hydroxylamine sulfate;

[0038] (4) Physical separation step: The reactants in step (3) are separated into layers, wherein the upper layer is a light phase containing an organic solvent containing ketones, and the lower layer is a heavy phase containing hydroxylamine sulfate and caprolactam; the organic solvent containing ketones is returned to step (1) for ammoximation reaction, or after removing the solvent, is returned to step (1) for ammoximation reaction; the lower layer is subjected to sedimentation, centrifugal separation, and drying to obtain a crude caprolactam solution and hydroxylamine sulfate salt. Preferably, the organic solvent is one or more mixed solvents such as n-pentane, cyclopentane or cyclohexane.

[0039] Preferably, the stratification in the step (4) is static stratification.

[0040] Example 1): A method for co-producing caprolactam and hydroxylamine sulfate comprises: (1) a heterogeneous ammoximation reaction: using water as a medium, 32.4 g of a ketone, 7.10 g of ammonia, and 36.4 g of 27.5% hydrogen peroxide in the presence of a catalyst, preferably cyclohexanone, to produce ketone oxime, and then extracting the oxime produced by the reaction with an alkane solvent to obtain an oxime solution, wherein the mass ratio of oxime to solvent in the alkane oxime solution is 1:(1.5-6);

[0041] (2) Hydrolysis reaction: adding an appropriate amount of desalted water to caprolactam sulfate to carry out hydrolysis reaction, stirring, controlling the temperature at 0-80°C, obtaining a hydrolysis reactant, obtaining a hydrolysis reactant caprolactam sulfuric acid solution, and obtaining caprolactam sulfate by rearrangement reaction, rearrangement reaction: sending the alkoxime solution to the rearrangement reactor to react with fuming sulfuric acid to produce caprolactam sulfate, preferably, the rearrangement reaction is a one-stage or multi-stage rearrangement; the rearrangement reaction equipment is a horizontal rearrangement, or a solvent rearrangement;

[0042] (3) Co-production of caprolactam and hydroxylamine sulfate: adding the alkanoxime solution obtained in step (1) to the hydrolysis reactant caprolactam sulfuric acid solution to obtain a reactant. Preferably, in step (3), the temperature is controlled between 0 and 65° C., and the reaction time is 0.5-4 h;

[0043] (4) Physical separation step: The reactants in step (3) are separated into layers, wherein the upper layer is a light phase containing an organic solvent containing ketones, and the lower layer is a heavy phase containing hydroxylamine sulfate and caprolactam; the organic solvent containing ketones is returned to step (1) for ammoximation reaction, or after removing the solvent, is returned to step (1) for ammoximation reaction; the lower layer is subjected to sedimentation, centrifugal separation, and drying to obtain a crude caprolactam solution and hydroxylamine sulfate salt. Preferably, the organic solvent is one or more mixed solvents such as n-pentane, cyclopentane or cyclohexane.

[0044] The reactants include caprolactam and hydroxylamine sulfate; the caprolactam / cyclohexanone contents in the organic phase and the aqueous phase are analyzed by gas chromatography, the hydroxylamine sulfate content in the aqueous phase is analyzed by titration, and the caprolactam yield and the hydroxylamine yield are quantitatively calculated.

[0045] Example Caprolactam yield Hydroxylamine sulfate yield 1 99.2％ 45.2％

[0046] Example 2): The steps (1), (2) and (4) are the same as those in Example 1, but the step (3) is different.

[0047] (3) Co-production of caprolactam and hydroxylamine sulfate: adding the alkanoxime solution obtained in step (1) to the hydrolysis reaction product to obtain a reactant. Preferably, the temperature in step 3) is controlled between 45 and 95° C., and the reaction time is 0.5-3 h;

[0048] The reactants include caprolactam and hydroxylamine sulfate; the caprolactam / cyclohexanone contents in the organic phase and the aqueous phase are analyzed by gas chromatography, the hydroxylamine sulfate content in the aqueous phase is analyzed by titration, and the caprolactam yield and the hydroxylamine yield are quantitatively calculated.

[0049] Example Caprolactam yield Hydroxylamine sulfate yield 2 99.15％ 48.3％

[0050] Example 3): The steps (1), (2) and (4) are the same as those in Example 1, but the step (3) is different.

[0051] (3) Co-production of caprolactam and hydroxylamine sulfate: adding the alkanoxime solution obtained in step (1) to the hydrolysis reactant to obtain a reactant. Preferably, in step 3), the temperature is controlled between 65 and 110° C., the reaction time is 4 to 6 hours, and the pressure is controlled between 50 kPa and 0.1 MPa absolute pressure;

[0052] The reactants include caprolactam and hydroxylamine sulfate; the caprolactam / cyclohexanone contents in the organic phase and the aqueous phase are analyzed by gas chromatography, the hydroxylamine sulfate content in the aqueous phase is analyzed by titration, and the caprolactam yield and the hydroxylamine yield are quantitatively calculated.

[0053] Example Caprolactam yield Hydroxylamine sulfate yield 3 99.31％ 57.42％

[0054] Example 4): The steps (1), (2) and (4) are the same as those in Example 1, but the step (3) is different.

[0055] (3) Co-production of caprolactam and hydroxylamine sulfate: adding the alkanoxime solution obtained in step (1) to the hydrolysis reactant to obtain a reactant. Preferably, in step 3), the temperature is controlled between 75 and 120° C., the reaction time is 4 to 6 hours, and the pressure is controlled between 90 kPa and 0.2 MPa absolute pressure;

[0056] The reactants include caprolactam and hydroxylamine sulfate;

[0057] The reactants include caprolactam and hydroxylamine sulfate; the caprolactam / cyclohexanone contents in the organic phase and the aqueous phase are analyzed by gas chromatography, the hydroxylamine sulfate content in the aqueous phase is analyzed by titration, and the caprolactam yield and the hydroxylamine yield are quantitatively calculated.

[0058] Example Caprolactam yield Hydroxylamine sulfate yield 4 99.18％ 59.13％

[0059] Example 5): The steps (1), (2) and (4) are the same as those in Example 1, but the step (3) is different.

[0060] (3) Co-production of caprolactam and hydroxylamine sulfate: adding the alkanoxime solution obtained in step (1) to the hydrolysis reactant to obtain a reactant. Preferably, in step 3), the temperature is controlled between 98 and 120° C., the reaction time is 4 to 6 hours, and the pressure is controlled between 85 kPa and 0.2 MPa absolute pressure;

[0061] The reactants include caprolactam and hydroxylamine sulfate; the caprolactam / cyclohexanone contents in the organic phase and the aqueous phase are analyzed by gas chromatography, the hydroxylamine sulfate content in the aqueous phase is analyzed by titration, and the caprolactam yield and the hydroxylamine yield are quantitatively calculated.

[0062] Example Caprolactam yield Hydroxylamine sulfate yield 5 99.19％ 61.18％

[0063] Example 6): The steps (1), (2) and (4) are the same as those in Example 1, but the step (3) is different.

[0064] (3) Co-production of caprolactam and hydroxylamine sulfate: adding the alkanoxime solution obtained in step (1) to the hydrolysis reactant to obtain a reactant. Preferably, in step 3), the temperature is controlled between 25 and 65° C., the reaction time is 4 to 6 hours, and the pressure is controlled between 50 kPa and 0.08 MPa absolute pressure;

[0065] The reactants include caprolactam and hydroxylamine sulfate; the caprolactam / cyclohexanone contents in the organic phase and the aqueous phase are analyzed by gas chromatography, the hydroxylamine sulfate content in the aqueous phase is analyzed by titration, and the caprolactam yield and the hydroxylamine yield are quantitatively calculated.

[0066] Example Caprolactam yield Hydroxylamine sulfate yield 6 99.28％ 42.5％

[0067] Example 7): The steps (1), (2) and (4) are the same as those in Example 1, but the step (3) is different.

[0068] (3) Co-production of caprolactam and hydroxylamine sulfate: adding the alkanoxime solution obtained in step (1) to the hydrolysis reactant to obtain a reactant. Preferably, in step 3), the temperature is controlled between 25 and 60° C., the reaction time is 4 to 6 hours, and the pressure is controlled between 50 kPa and 0.05 MPa absolute pressure;

[0069] The reactants include caprolactam and hydroxylamine sulfate; the caprolactam / cyclohexanone contents in the organic phase and the aqueous phase are analyzed by gas chromatography, the hydroxylamine sulfate content in the aqueous phase is analyzed by titration, and the caprolactam yield and the hydroxylamine yield are quantitatively calculated.

[0070] Example Caprolactam yield Hydroxylamine sulfate yield 7 99.28％ 39.8％

[0071] Example 8): The steps (1), (2) and (4) are the same as those in Example 1, but the step (3) is different.

[0072] (3) Co-production of caprolactam and hydroxylamine sulfate: adding the alkanoxime solution obtained in step (1) to the hydrolysis reactant to obtain a reactant. Preferably, in step 3), the temperature is controlled between 25 and 65° C., the reaction time is 4 to 6 hours, and the pressure is controlled between 50 kPa and 0.08 MPa absolute pressure;

[0073] The reactants include caprolactam and hydroxylamine sulfate; the caprolactam / cyclohexanone contents in the organic phase and the aqueous phase are analyzed by gas chromatography, the hydroxylamine sulfate content in the aqueous phase is analyzed by titration, and the caprolactam yield and the hydroxylamine yield are quantitatively calculated.

[0074] Example Caprolactam yield Hydroxylamine sulfate yield 8 99.32％ 37.9％

[0075] Example 9): The steps (1), (2) and (4) are the same as those in Example 1, but the step (3) is different.

[0076] (3) Co-production of caprolactam and hydroxylamine sulfate: adding the alkanoxime solution obtained in step (1) to the hydrolysis reactant to obtain a reactant. Preferably, in step 3), the temperature is controlled between 25 and 58° C., the reaction time is 4 to 6 hours, and the pressure is controlled between 50 kPa and 0.05 MPa absolute pressure;

[0077] The reactants include caprolactam and hydroxylamine sulfate; the caprolactam / cyclohexanone contents in the organic phase and the aqueous phase are analyzed by gas chromatography, the hydroxylamine sulfate content in the aqueous phase is analyzed by titration, and the caprolactam yield and the hydroxylamine yield are quantitatively calculated.

[0078] Example Caprolactam yield Hydroxylamine sulfate yield 9 99.34％ 38.45％

[0079] Example 10): The steps (1), (2) and (4) are the same as those in Example 1, but the step (3) is different.

[0080] (3) Co-production of caprolactam and hydroxylamine sulfate: adding the alkanoxime solution obtained in step (1) to the hydrolysis reactant to obtain a reactant. Preferably, in step 3), the temperature is controlled between 25 and 56° C., the reaction time is 4 to 6 hours, and the pressure is controlled between 50 kPa and 0.04 MPa absolute pressure;

[0081] The reactants include caprolactam and hydroxylamine sulfate; the caprolactam / cyclohexanone contents in the organic phase and the aqueous phase are analyzed by gas chromatography, the hydroxylamine sulfate content in the aqueous phase is analyzed by titration, and the caprolactam yield and the hydroxylamine yield are quantitatively calculated.

[0082] Example Caprolactam yield Hydroxylamine sulfate yield 10 99.22％ 37.6％

Claims

1. A method for co-producing caprolactam and hydroxylamine sulfate, characterized in that: The method comprises the following steps: (1) Ammoximation reaction: ketone, ammonia and hydrogen peroxide are reacted at a certain temperature under the action of a titanium-silicon catalyst to produce an oxime solution; the oxime solution is obtained by extraction with an alkane solvent during the ammoximation reaction, wherein the alkane solvent is one or a mixture of n-pentane, cyclopentane or cyclohexane; the mass ratio of oxime to solvent in the oxime solution is 1:(0.5~10); (2) Hydrolysis reaction: caprolactam sulfate is added with an appropriate amount of desalted water, stirred, and the hydrolysis temperature is controlled to carry out a hydrolysis reaction to obtain a caprolactam sulfuric acid solution as a hydrolysis reaction product; caprolactam sulfate is obtained by a rearrangement reaction of fuming sulfuric acid with molten pure oxime, or by a Beckmann rearrangement reaction of fuming sulfuric acid with a cyclohexanone oxime-alkane solution; (3) Co-production of caprolactam and hydroxylamine sulfate: Add oxime solution to caprolactam sulfuric acid solution, and react at a certain temperature and pressure to obtain caprolactam and hydroxylamine sulfate solution; (4) Physical separation: The reactants in step (3) are separated into layers, wherein the upper layer is a light phase containing an organic solvent containing ketone, and the lower layer is a heavy phase containing an aqueous phase containing hydroxylamine sulfate and caprolactam; (5) The organic solvent containing ketone is returned to step (1) for ammoximation reaction; the lower layer is subjected to sedimentation, centrifugal separation, and drying to obtain a crude caprolactam solution and hydroxylamine sulfate salt.

2. The method for co-producing caprolactam and hydroxylamine sulfate according to claim 1, wherein: In the step (1), the ammoximation reaction is carried out by reacting the ketone with ammonia and hydrogen peroxide at a certain temperature and pressure under the catalytic action of a titanium-silicon catalyst using water as a solvent, and separating the obtained oxime; or by reacting the ketone with ammonia and hydrogen peroxide at a certain temperature and pressure under the catalytic action of a titanium-silicon catalyst using a hydrocarbon as a solvent, and separating the obtained oxime.

3. The method for co-producing caprolactam and hydroxylamine sulfate according to claim 1, wherein: In step (2), the mass ratio of caprolactam sulfate to water is 1:2.5 to 1:0.3, the temperature is controlled between 0 and 120° C., the pressure is controlled between 50 kPa and 0.2 MPa absolute pressure, and the hydrolysis time is 0.5 to 2 h.

4. The method for co-producing caprolactam and hydroxylamine sulfate according to claim 1, wherein: In step (3), the reaction temperature is controlled between 0 and 120° C., the pressure is controlled between 50 kPa and 0.2 MPa absolute pressure, and the hydrolysis time is 0.5-6 h.

5. The method for co-producing caprolactam and hydroxylamine sulfate according to claim 1, wherein: The stratification in step (4) is static stratification, and the drying in step (5) is fluidized bed drying or rotary disk drying.

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