Method and system for preparing oxime via ammoximation reaction

Abstract

Disclosed in the present invention are a method and system for preparing an oxime via an ammoximation reaction. The method comprises: (1) mixing a carbonyl compound, ammonia, and a circulating catalyst slurry at a specific feed ratio of the carbonyl compound to the circulating catalyst slurry to obtain a mixed stream, and then bringing the mixed stream into contact with hydrogen peroxide for an ammoximation reaction to obtain a reaction slurry; (2) mixing the reaction slurry with an organic solvent and then performing two-phase separation to obtain an oxime-containing organic phase and a catalyst-containing aqueous phase; (3) optionally, washing the organic phase obtained in step (2) with optional water and then performing separation to obtain an organic solvent and an oxime product; and (4) filtering the aqueous phase obtained in step (2) and then returning same to step (1) to provide at least part of the circulating catalyst slurry. The method and system for preparing an oxime according to the present invention significantly prolong the service life of a catalyst, improve the operating stability of a system, reduce the consumption of catalyst, and improve the quality of the prepared oxime product.

Description

Methods and systems for preparing oximes via ammonoximation reaction Technical Field

[0001] This invention relates to the field of organic chemical raw material production, and more specifically to a method and system for preparing oximes via ammonoximation reaction. Background Technology

[0002] In the development of the chemical industry, oximes are a very important class of organic intermediates. Taking cyclohexanone oxime as an example, it is mainly used to produce caprolactam, a key raw material for manufacturing polyamide-6 (nylon-6) fibers and engineering plastics. Nylon-6, due to its excellent abrasion resistance, mechanical properties, and chemical stability, is widely used in the manufacture of tire cords, ropes, mechanical parts, and clothing, among other products. With the booming development of these downstream industries, the demand for caprolactam continues to rise, making the preparation technology of cyclohexanone oxime one of the key research areas in the chemical industry. The traditional method for producing ketone / aldehyde oximes is mainly the hydroxylamine process, which uses ketones / aldehydes and hydroxylamine salts (such as hydroxylamine sulfate) as raw materials and reacts them in an acidic medium. This reaction is accompanied by the generation of a large amount of ammonium sulfate as a byproduct, which not only leads to low raw material atom utilization but also results in extremely high costs for subsequent ammonium sulfate processing. At the same time, the discharge of large amounts of ammonium sulfate leads to environmental problems such as eutrophication of water bodies and soil acidification. In addition, the acidic conditions during the reaction process place high demands on the materials used in the reaction equipment, requiring the use of acid-resistant materials, which increases equipment investment and maintenance costs.

[0003] From a green chemistry perspective, developing a more environmentally friendly and efficient method for oxime preparation has become a research hotspot. Currently, the catalytic ammonium oximation method is widely used in industry. It uses titanium silicate molecular sieves as catalysts, and in the presence of a solvent (such as tert-butanol), ketones / aldehydes undergo an ammonium oximation reaction with ammonia and hydrogen peroxide to directly generate the corresponding oxime. This method has high atom utilization, and the main byproduct is water, which aligns with the principles of green chemistry, reduces environmental pollution, and lowers production costs. However, the need for solvent recycling results in relatively high energy consumption. In recent years, a novel ammonium oximation process without tert-butanol solvent has attracted widespread scientific attention, aiming to overcome the high energy consumption bottleneck faced by traditional organic solvent systems in the ammonium oximation process.

[0004] However, existing ammonia oxime processes that do not use organic solvents such as tert-butanol in the reaction section generally suffer from problems such as short catalyst life, poor system stability, high catalyst consumption, and poor oxime product quality. Summary of the Invention

[0005] The purpose of this invention is to overcome at least one of the following problems existing in the methods and systems for preparing oximes via ammonium oximation reactions: low catalyst lifespan, difficulty in separating reaction products from the catalyst, and easy catalyst loss. This invention provides a method and system for preparing oximes. The method and system for preparing oximes according to this invention significantly extend catalyst lifespan, improve system operational stability, reduce catalyst consumption, and produce high-quality oxime products.

[0006] To achieve the above objectives, a first aspect of the present invention provides a method for preparing oximes, the method comprising the following steps:

[0007] (1) A mixture stream is obtained by mixing carbonyl compound, ammonia and circulating catalyst slurry, wherein the feed ratio of carbonyl compound to circulating catalyst slurry by mass is 1:10-50, and then the mixture stream is contacted with hydrogen peroxide to carry out an ammonium oxime reaction to obtain a reaction slurry;

[0008] (2) The reaction slurry is mixed with an organic solvent and then the two phases are separated to obtain an oxime-containing organic phase and a catalyst-containing aqueous phase;

[0009] (3) Optionally, the organic phase obtained in step (2) is washed with water and then separated to obtain an organic solvent and an oxime product;

[0010] (4) The aqueous phase obtained in step (2) is filtered and returned to step (1) to provide at least a portion of the circulating catalyst slurry.

[0011] A second aspect of the present invention provides a system for preparing oximes, the system comprising a reaction unit, an optional water washing unit, an optional extraction unit, and an optional product separation unit, the reaction unit comprising at least one reactor, a catalyst separator, and a filter;

[0012] The reactor is connected to a circulating catalyst slurry pipeline and a hydrogen peroxide feed pipeline, respectively. The circulating catalyst slurry pipeline is provided with a carbonyl compound inlet and an ammonia inlet. The reactor is used to contact a mixture stream containing carbonyl compounds, ammonia and circulating catalyst slurry from the circulating catalyst slurry pipeline with hydrogen peroxide from the hydrogen peroxide feed pipeline to carry out an ammonium oxime reaction. The circulating catalyst slurry pipeline is configured such that the feed ratio of carbonyl compounds to circulating catalyst slurry by mass is 1:10-50.

[0013] The reactor and the catalyst separator are connected by a pipeline, which is provided with an organic solvent inlet; the catalyst separator is provided with an aqueous phase outlet and an organic phase outlet, for separating the mixed extract stream containing the reaction slurry from the reactor and the organic solvent into two phases.

[0014] The organic phase outlet of the catalyst separator is connected to the optional product separation unit via the optional water washing unit, and the aqueous phase outlet of the catalyst separator is connected to the reactor via the filter and the circulating catalyst slurry pipeline;

[0015] The product separation unit is used to separate the organic phase from the catalyst separator to obtain organic solvents and oxime products.

[0016] Through the above technical solution, the present invention has the following beneficial effects:

[0017] The method and system for preparing oximes provided by this invention mix carbonyl compounds, ammonia, and a circulating catalyst slurry at a specific feed ratio of carbonyl compounds to circulating catalyst slurry, and then contact the mixture stream with hydrogen peroxide. This allows the carbonyl compounds to rapidly disperse or even dissolve in the circulating catalyst slurry to achieve a near-homogeneous state before the carbonyl compounds, ammonia, and hydrogen peroxide come into contact in the reactor for the ammonium oxime reaction. This significantly extends the catalyst's lifespan, improves the system's operational stability, and effectively reduces catalyst consumption while maintaining high carbonyl compound conversion and oxime selectivity.

[0018] This invention further involves mixing the ammonium oximation reaction slurry with an organic solvent, followed by two-phase separation. Improved natural phase separation achieves better separation of the catalyst and reaction products. The catalyst slurry is then returned to the ammonium oximation reactor at a specific feed ratio to continue participating in the reaction, ensuring efficient catalyst utilization. Water washing and separation of the organic phase effectively removes impurities from the oxime product, particularly oil-soluble impurities, resulting in a high-quality oxime product. Attached Figure Description

[0019] The accompanying drawings, which are included in and form part of this specification, illustrate one or more embodiments and explain these embodiments together with the detailed description below. The drawings are not necessarily drawn to scale. Any values ​​or dimensions in the drawings are for illustrative purposes only and may or may not represent actual or preferred values ​​or dimensions.

[0020] Figure 1 is a schematic diagram of a system for preparing oximes according to a specific embodiment of the present invention.

[0021] Figure 2 is a schematic diagram of a system for preparing oximes according to another specific embodiment of the present invention.

[0022] Figure 3 is a schematic diagram of a catalyst separator according to a specific embodiment of the present invention.

[0023] Figure 4 is a schematic diagram of a catalyst separator according to another specific embodiment of the present invention.

[0024] Explanation of reference numerals in the attached figures

[0025] In Figures 1 and 2: 1 Reactor; 2 Heat exchanger; 3 Catalyst separator; 4 Membrane filter; 5 Tail gas absorption unit; 6 Water washing unit; 7 Product separation unit; 8 Extraction unit; 9 Deammoniation unit; 10 Circulating catalyst slurry pipeline; 11 Organic solvent pipeline.

[0026] In Figures 3 and 4: 1-Reservoir body; 2-Agitator; 3-Inner extension tube; 4-Anti-impact baffle; 5-Inner sleeve; 6-Overflow weir; 7-Organic phase outlet; 8-Aqueous phase outlet; 9-Gas phase outlet; 10-Gas phase balance port; 11-Membrane module; 12-Collection tube; 13-Clear liquid outlet. Detailed Implementation

[0027] The specific embodiments of this application will be described in detail below. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit this application.

[0028] Any specific numerical values ​​disclosed herein (including the endpoints of numerical ranges) are not limited to their exact values, but should be understood to also include values ​​close to the exact value, such as all possible values ​​within ±5% of the exact value. Furthermore, with respect to the disclosed numerical ranges, one or more new numerical ranges can be obtained by arbitrarily combining the endpoint values ​​of the range, the endpoint values ​​with specific point values ​​within the range, and the specific point values ​​themselves; these new numerical ranges should also be considered as specifically disclosed herein.

[0029] Unless otherwise stated, the terms used herein have the same meaning as commonly understood by those skilled in the art, and if a term is defined herein and its definition differs from the common understanding in the art, the definition herein shall prevail.

[0030] The expressions “comprising” or “including” in this document should be interpreted as including all specifically mentioned features as well as optional, additional, or unspecified features. As used herein, the use of the terms “comprising” or “including” also discloses schemes in which no other features besides the specifically mentioned features are present, such as expressions “consistently composed of” and “composed of”.

[0031] It should be noted that in the description of this application, the terms "first" and "second" are used only for the convenience of describing different technical features, such as devices or materials, and should not be construed as indicating or implying a sequential relationship or the number of indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature.

[0032] The first aspect of the present invention provides a method for preparing oximes, the method comprising the following steps:

[0033] (1) A mixture stream is obtained by mixing carbonyl compound, ammonia and circulating catalyst slurry, wherein the feed ratio of carbonyl compound to circulating catalyst slurry by mass is 1:10-50, and then the mixture stream is contacted with hydrogen peroxide to carry out an ammonium oxime reaction to obtain a reaction slurry;

[0034] (2) The reaction slurry is mixed with an organic solvent and then the two phases are separated to obtain an oxime-containing organic phase and a catalyst-containing aqueous phase;

[0035] (3) Optionally, the organic phase obtained in step (2) is washed with water and then separated to obtain an organic solvent and an oxime product;

[0036] (4) The aqueous phase obtained in step (2) is filtered and returned to step (1) to provide at least a portion of the circulating catalyst slurry.

[0037] In this invention, by mixing carbonyl compounds, ammonia, and circulating catalyst slurry at a specific feed ratio of carbonyl compounds to circulating catalyst slurry, and then contacting the mixture stream with hydrogen peroxide, the lifespan of the catalyst is significantly extended, the system operating stability is improved, and the consumption of catalyst is effectively reduced while maintaining high carbonyl compound conversion and oxime selectivity.

[0038] In some embodiments of the present invention, the feed ratio of the carbonyl compound to the circulating catalyst slurry in step (1) is 1:10-50 by mass. For example, it can be a specific but not limiting value or any range between two such values, such as 1:50, 1:45, 1:40, 1:35, 1:32, 1:30, 1:28, 1:26, 1:25, 1:24, 1:22, 1:20, 1:19, 1:18, 1:17, 1:16, 1:15, 1:14, 1:13, 1:12, 1:11, 1:10, etc., preferably 1:15-30, more preferably 1:16-20. Unwilling to be constrained by specific theories, the inventors discovered through research that when the carbonyl compound is fed to the circulating catalyst slurry at a ratio of less than 1:10, the carbonyl compound can be rapidly dispersed and even dissolved in the circulating catalyst slurry to reach a near-homogeneous state. This allows the carbonyl compound in this state to come into contact with hydrogen peroxide in the reactor, significantly improving the efficiency of the ammonium oxime reaction and the lifespan of the catalyst, thus improving the stability of the system operation. When the feed ratio is further reduced, for example, below the lower limit of 1:50, the residence time of the reactant stream in the reactor and separator is too short, requiring a corresponding increase in the size of the equipment. This reduces the effective catalyst concentration in the system, which is detrimental to cost-effectiveness and large-scale production.

[0039] In some embodiments of the present invention, step (2) further includes: heating the reaction slurry before mixing it with an organic solvent.

[0040] In some other embodiments of the present invention, step (2) further includes: heating the mixture of the reaction slurry and the organic solvent, and then performing two-phase separation.

[0041] In some other embodiments of the present invention, step (2) further includes: mixing a portion of the reaction slurry with an organic solvent, and then performing two-phase separation to obtain an oxime-containing organic phase and a catalyst-containing aqueous phase, and returning the remaining portion of the reaction slurry to the ammonium oxime reaction described in step (1) after heat removal.

[0042] In this invention, the heat recovered from the reaction slurry, the mixture of the reaction slurry and the organic solvent, or the remaining portion of the reaction slurry can be reused to improve energy efficiency.

[0043] In some preferred embodiments of the present invention, step (2) further includes mixing a portion of the reaction slurry with an organic solvent, followed by two-phase separation to obtain an oxime-containing organic phase and a catalyst-containing aqueous phase. The remaining portion of the reaction slurry is then returned to the ammonium oxime reaction in step (1) after being heated. In this case, the mass ratio of the partial reaction slurry to the remaining reaction slurry is 1:2-8, for example, specific but not limiting values ​​such as 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, or any range between the two, preferably 1:3-5. The inventors have discovered that by controlling the mass ratio of the partial reaction slurry to the remaining reaction slurry within a specific range, effective heat recovery can be further achieved.

[0044] In some preferred embodiments of the present invention, in step (2), after heat treatment, the temperature of the reaction slurry, the mixture of the reaction slurry and the organic solvent, or the remaining portion of the reaction slurry is 40-85°C, preferably 50-80°C. Preferably, after heat treatment, the temperature of the reaction slurry, the mixture of the reaction slurry and the organic solvent, or the remaining portion of the reaction slurry is 5-20°C lower than the temperature of the corresponding stream before heat treatment.

[0045] In some preferred embodiments of the present invention, the mass ratio of the organic solvent to the oxime in the reaction slurry is 0.5-5:1, for example, it can be a specific but not limiting value or any range between two such values, such as 0.5:1, 1:1, 1.5:1, 2:1, 2.5:1, 3:1, 3.5:1, 4:1, 4.5:1, 5:1, etc., preferably 1-3:1. Using the above preferred embodiments is beneficial for achieving effective separation of the catalyst and reaction products, and also for controlling the concentration of oxime in the circulating catalyst slurry.

[0046] In this invention, the concentration of oxime in the circulating catalyst slurry can be controlled by controlling the amount of organic solvent added. In some preferred embodiments of this invention, the mass fraction of oxime in the circulating catalyst slurry is 0.1-4%, for example, it can be a specific but not limiting value or any range between 0.1%, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, etc., preferably 0.5-3%. Adopting the above preferred embodiments is beneficial for extending the service life of the catalyst, reducing catalyst consumption, and improving the quality of the oxime product.

[0047] In this invention, there are no particular limitations on the method of mixing the carbonyl compound, ammonia and the circulating catalyst slurry in step (1), as long as it is ensured that the carbonyl compound, ammonia and the circulating catalyst slurry are mixed evenly before contact with hydrogen peroxide.

[0048] In some preferred embodiments of the present invention, in step (1), the molar ratio of hydrogen peroxide to the carbonyl compound is 1-1.5:1, preferably 1-1.3:1. Using the above preferred embodiments is beneficial for improving the conversion rate of the carbonyl compound and the oxime selectivity.

[0049] In some preferred embodiments of the invention, the hydrogen peroxide is provided by hydrogen peroxide solution. The concentration of hydrogen peroxide in the hydrogen peroxide solution is not particularly limited. Preferably, the mass concentration of the hydrogen peroxide is 15-80 wt%, more preferably 20-70 wt%.

[0050] In some preferred embodiments of the present invention, the hydrogen peroxide is added to the ammonium oxime reactor via a feed distributor, preferably from the bottom of the ammonium oxime reactor, and more preferably from near the stirring device of the ammonium oxime reactor. The form of the feed distributor is not particularly limited; for example, it can be at least one of a loop type, a branch type, and a nozzle type, preferably a loop type.

[0051] In some preferred embodiments of the present invention, in step (1), the molar ratio of ammonia to carbonyl compound is 1-1.5:1, preferably 1-1.3:1.

[0052] In some preferred embodiments of the present invention, the mass fraction of the catalyst in the circulating catalyst slurry is 0.1%-15%, for example, it can be a specific but not limiting value or any range between 0.1%, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 5.5%, 6%, 6.5%, 7%, 7.5%, 8%, 8.5%, 9%, 9.5%, 10%, 11%, 12%, 13%, 14%, 15%, etc., preferably 1%-10%. Using the above preferred embodiments helps to achieve a balance between extending the stable operating time of the system and the load and cost-effectiveness of the filtration system.

[0053] In this invention, the type of catalyst is not particularly limited, and any conventional ammonium oxime catalyst in the art can be used. Preferably, the catalyst comprises a titanium silicate molecular sieve, and the titanium silicate molecular sieve is preferably selected from at least one of TS-1, TS-2, Ti-ZSM-5, Ti-ZSM-12, Ti-ZSM-48, Ti-β, Ti-MCM-41, Ti-MOR, Ti-MWW, and Ti-SBA-15.

[0054] In this invention, the form of the catalyst is not particularly limited. It can be in the form of molecular sieve powder or a shaped catalyst formed by arbitrary shaping. Those skilled in the art can choose according to actual needs.

[0055] In some preferred embodiments of the present invention, no organic solvent is added in the ammonium oxime reaction in step (1). The solvent may be any organic solvent commonly used in the art, such as tert-butanol.

[0056] In some preferred embodiments of the present invention, the conditions for the ammonium oximation reaction include: a reaction temperature of 60-100°C and a reaction pressure of 0-1 MPaG. More preferably, the conditions for the ammonium oximation reaction include: a reaction temperature of 80-95°C and a reaction pressure of 0.1-0.5 MPaG. In this invention, unless otherwise specified, all pressures refer to gauge pressure.

[0057] In this invention, the type of reactor for the ammonium oximation reaction is not particularly limited. Preferably, the ammonium oximation reaction is carried out in a stirred tank reactor. In this invention, the stirred tank reactor refers to a tank reactor equipped with a stirring device.

[0058] In this invention, the number of reactors for the ammonium oxime reaction is not particularly limited. Those skilled in the art can select one or more reactors according to actual production needs, and two or more reactors can be connected in series and / or parallel. Preferably, the number of reactors is 1-4, for example 1-2.

[0059] In some preferred embodiments of the invention, each reactor is provided with an agitator. The type of agitator is not particularly limited. Preferably, the agitator is selected from at least one of paddle, propeller, and turbine types.

[0060] In this invention, the number of layers of the stirring paddle is not particularly limited. Preferably, the number of stirring paddle layers is 1-3.

[0061] In some preferred embodiments of the invention, each reactor is provided with a baffle. The number of baffles is not particularly limited. Preferably, each reactor has 2-6 baffles.

[0062] In this invention, when multiple reactors are connected in series and / or in parallel, preferably each reactor is independently connected to a hydrogen peroxide feed line so that hydrogen peroxide can be fed into multiple reactors simultaneously.

[0063] In some preferred embodiments of the present invention, step (1) further includes: contacting the gas generated by the ammonium oximation reaction with demineralized water to absorb ammonia from the gas, and returning the resulting absorbent to the ammonium oximation reaction in step (1). In the present invention, the amount of demineralized water is not particularly limited, and those skilled in the art can adjust it conventionally according to actual conditions.

[0064] According to the present invention, in step (2), the mixed extract stream obtained by mixing the reaction slurry and the organic solvent is subjected to two-phase separation. The oxime is extracted into the organic solvent to form an oxime-containing organic phase, and the catalyst enters the aqueous phase to form a catalyst-containing aqueous phase. It should be noted that in the present invention, the reaction slurry and the organic solvent undergo extraction during the mixing process to obtain the mixed extract stream.

[0065] In this invention, the carbonyl compound is selected from C3-C4. 10 Aliphatic ketones, C5-C 10 Alicyclic ketones, C6-C 10 Aromatic ketones, C5-C 10 Alicyclic aldehydes, C6-C 10 At least one of the aromatic aldehydes, preferably at least one of cyclohexanone, acetone, methyl ethyl ketone, cyclopentanone, acetophenone, p-hydroxyacetophenone, furfural, benzaldehyde and p-methylbenzaldehyde, more preferably at least one of acetone, methyl ethyl ketone, cyclopentanone and cyclohexanone.

[0066] In this invention, the type of organic solvent used in step (2) is not particularly limited; any conventional organic solvent that is insoluble or slightly soluble in water can be used in this invention. Preferably, the organic solvent is selected from C6-C6. 12 Alkanes, C5-C 11 Cycloalkanes, C6-C 10 At least one of the aromatic hydrocarbons, preferably selected from C6-C 10 Aromatics and C6-C 10 At least one of the cycloalkanes, such as n-hexane, cyclohexane, benzene, toluene, isohepyl alcohol, isooctyl alcohol, etc., more preferably toluene and / or cyclohexane.

[0067] In some preferred embodiments of the present invention, the two-phase separation in step (2) is carried out in a catalyst separator.

[0068] In some preferred embodiments of the present invention, the catalyst separator includes a vessel body and a stirrer, an inner extension tube, and an inner sleeve disposed in the vessel body; the inner sleeve is sleeved inside the inner extension tube, and a gas phase balance port is provided on the side wall of the inner extension tube; the stirring paddle of the stirrer is disposed in the aqueous phase section of the vessel body for stirring the aqueous phase.

[0069] In some embodiments of the present invention, the two-phase separation in step (2) is carried out by the following process: the mixed extract stream containing the reaction slurry and the organic solvent is transported to the inner tube through the inner sleeve installed inside the inner tube, and then transported to the vessel body through the inner tube for two-phase separation to obtain the organic phase and the aqueous phase.

[0070] In this invention, the catalyst separator, through the combination of an inner extension tube and an inner sleeve, can reduce the amount of catalyst carried in the organic phase; the stirrer is configured to prevent catalyst deposition in the reactor and avoid back mixing of the organic and aqueous phases, ensuring continuous and stable separation of the two phases and catalyst circulation.

[0071] In some preferred embodiments of the present invention, the top end of the inner tube is located outside the vessel body, and the bottom end of the inner tube is located inside the vessel body. By positioning the bottom end of the inner tube inside the vessel body, a mixed extract stream containing the reaction slurry obtained from the ammonium oxime reaction and an organic solvent can be transported into the vessel body for two-phase separation.

[0072] In some preferred embodiments of the present invention, the top end of the inner sleeve is flush with the top end of the inner extension tube, and the top of the annular space formed by the inner sleeve and the inner extension tube is closed.

[0073] In some preferred embodiments of the present invention, the length ratio of the inner extension tube to the inner sleeve tube is 30-5:1, preferably 25-8:1. By optimizing the length ratio of the inner extension tube to the inner sleeve tube, catalyst entrainment loss can be reduced.

[0074] In some preferred embodiments of the present invention, the ratio of the length of the inner tube extending below the upper tangent of the vessel body to the vertical distance between the upper and lower tangents of the vessel body is 0.3-0.95:1, preferably 0.4-0.9:1. By optimizing the position of the inner tube in the vessel body, catalyst oil phase entrainment can be effectively suppressed.

[0075] In this invention, it should be noted that the upper tangent of the vessel body refers to the tangential section at the junction of the upper end cap and the cylinder wall; the lower tangent of the vessel body refers to the tangential section at the junction of the lower end cap and the cylinder wall. In this invention, the portion of the inner tube outside the vessel body has no effect on the separation effect of the catalyst separator.

[0076] In this invention, the rotational speed of the agitator is not particularly limited. The rotational speed is related to the selection of the agitator blade, the ratio of the blade diameter to the inner diameter of the vessel, etc. Those skilled in the art can adjust it according to the actual device structure, as long as it can prevent solid materials from depositing in the vessel and avoid back mixing of the organic phase and the aqueous phase. Preferably, the agitator rotational speed is 5-200 rpm.

[0077] In some preferred embodiments of the present invention, the bottom end of the stirrer is provided with a stirring paddle.

[0078] In this invention, the specific type of the stirring paddle is not particularly limited; any stirring device capable of preventing solid materials from depositing in the vessel is applicable. Preferably, the stirring paddle is selected from at least one of a propeller-type stirring paddle, a turbine-type stirring paddle, an anchor-type stirring paddle, and a frame-type stirring paddle.

[0079] In some preferred embodiments of the present invention, the number of layers of the stirring paddle is 1-3.

[0080] In some preferred embodiments of the present invention, an anti-impact baffle is provided at the bottom end of the inner tube. The anti-impact baffle is used to buffer the mixed extract stream containing the reaction slurry obtained from the ammonium oxime reaction and the organic solvent.

[0081] In some preferred embodiments of the present invention, an overflow weir is provided at the upper part of the vessel. The overflow weir is used to overflow the organic phase to obtain the organic phase product.

[0082] In this invention, the shape of the overflow weir is not particularly limited. Preferably, the overflow weir is an L-shaped plate, one end of which is connected to the inner wall of the vessel.

[0083] In some preferred embodiments of the invention, the catalyst separator is optionally equipped with a filter, such as a membrane filter.

[0084] In some preferred embodiments of the present invention, an organic phase outlet is provided at the upper part of the vessel body, and the organic phase outlet is connected to the overflow weir.

[0085] In some preferred embodiments of the present invention, the bottom of the vessel is provided with an aqueous phase outlet and an optional clear liquid outlet.

[0086] In some preferred embodiments of the present invention, a gas phase outlet is provided at the top of the vessel.

[0087] In some preferred embodiments of the present invention, the gas phase balance port is directly connected to the gas phase space above the vessel body, or the gas phase balance port is connected to the gas phase space above the vessel body through a pipeline.

[0088] In some preferred embodiments of the present invention, the shape of the lower end cap of the vessel body is at least one of ellipse, sphere and cone, preferably cone.

[0089] In some preferred embodiments of the present invention, the vessel body wall and / or the lower head side wall are provided with baffles, preferably 2-6 baffles.

[0090] In some preferred embodiments of the present invention, the conditions for the two-phase separation include: a pressure of 0-500 kPaG and a temperature of 40-90°C.

[0091] In some embodiments of the present invention, the water washing in step (3) includes washing the organic phase obtained in step (2) with water to separate the oxime-rich organic phase and the first supernatant.

[0092] In some preferred embodiments of the present invention, the water washing method includes: contacting the organic phase obtained in step (2) with demineralized water for water washing. The water washing method is not particularly limited, as long as it can remove impurities from the organic phase.

[0093] The present invention does not have a particular limitation on the amount of demineralized water used. Preferably, the mass ratio of the amount of demineralized water to the oxime in the oxime-containing organic phase is 0.1-1:1.

[0094] In some preferred embodiments of the present invention, the water washing stage in step (3) is 1-5 stages, preferably 1-3 stages. Adopting the above preferred embodiments helps to effectively remove impurities while reducing production costs.

[0095] In this invention, there are no particular limitations on the apparatus for separating the organic phase after water washing in step (3). For example, a distillation column or a rectification column can be used for separation.

[0096] In some preferred embodiments of the invention, step (4) includes membrane filtration of the aqueous phase obtained in step (2) to obtain a catalyst-rich stream and a second clear liquid; the obtained catalyst-rich stream is returned to step (1) to provide at least a portion of the circulating catalyst slurry.

[0097] In some preferred embodiments of the invention, the circulating catalyst slurry comprises the catalyst-rich stream obtained in step (4) and optionally a slurry containing fresh catalyst.

[0098] In this invention, a slurry containing fresh catalyst can be intermittently added according to specific operating conditions (e.g., when the mass fraction of catalyst in the catalyst-rich stream returning to step (1) decreases below the lower limit due to catalyst loss during long-term system operation). The slurry containing fresh catalyst is a slurry containing fresh catalyst prepared with water.

[0099] In some preferred embodiments of the present invention, the method includes: removing heat from the catalyst-rich stream obtained in step (4). Preferably, after heat removal, the temperature of the catalyst-rich stream is 15-30°C lower than the temperature of the stream before heat removal. This portion of heat recovered from the catalyst-rich stream can be reused to improve energy utilization.

[0100] In some preferred embodiments of the present invention, the filtration in step (4) is carried out in a membrane filter, which is located in the aqueous phase section of the catalyst separator or connected to the aqueous phase outlet of the catalyst separator.

[0101] In some preferred embodiments of the present invention, when the membrane filter is installed in the aqueous phase section of the catalyst separator, the membrane filtration in step (4) and the two-phase separation in step (3) can be carried out simultaneously in the same device to achieve synchronous operation of two-phase separation and filtration.

[0102] In this invention, it should be noted that when the membrane filter is installed in the aqueous phase section of the catalyst separator, the aqueous phase containing the catalyst obtained from the two-phase separation enters the membrane filter for membrane filtration, and the second clear liquid and the catalyst-rich stream obtained from the membrane filtration are discharged from the clear liquid outlet and the aqueous phase outlet of the catalyst separator, respectively; when the membrane filter is connected to the aqueous phase outlet of the catalyst separator, that is, when it is installed downstream of the catalyst separator, the aqueous phase containing the catalyst obtained from the two-phase separation is discharged from the aqueous phase outlet of the catalyst separator and sent to the membrane filter for membrane filtration through a pipeline.

[0103] In this invention, the configuration of the membrane filter is not particularly limited. Preferably, the membrane filter comprises at least one membrane module. When the membrane filter includes two or more membrane modules, the membrane modules can be connected in parallel and / or in series.

[0104] In some preferred embodiments of the present invention, the membrane filter is disposed in the aqueous phase section of the catalyst separator, and each membrane module includes a membrane tube and a manifold; or, the membrane filter is disposed downstream of the catalyst separator, and each membrane module includes a housing, a tube sheet, an end cap and a membrane tube, the membrane tube being placed inside the housing, and tube sheets being provided at both ends of the membrane tube for separating the flow streams inside and outside the membrane tube.

[0105] In some preferred embodiments of the present invention, when the membrane filter is installed in the aqueous phase section of the catalyst separator, the membrane filter is positioned below the anti-surge baffle, with one end of the membrane filter closed and the other end connected to the manifold. This preferred embodiment allows the membrane filter to be submerged in the aqueous phase, preventing the organic phase from passing through the membrane filter into the clear aqueous solution.

[0106] In some preferred embodiments of the present invention, the membrane filter is disposed in the aqueous phase section of the catalyst separator. The aqueous phase containing the catalyst permeates from the outer surface of the membrane tube to the inner side of the membrane tube to obtain a second clear liquid, which is collected by a collecting pipe and discharged from the clear liquid outlet of the catalyst separator through the clear liquid discharge pipeline. The resulting catalyst-rich stream is discharged from the aqueous phase outlet of the catalyst separator.

[0107] In some other preferred embodiments of the present invention, the membrane filter is located downstream of the catalyst separator. The aqueous phase containing the catalyst enters the membrane filter, flows through the center of the membrane tube to obtain a catalyst-rich stream, and permeates into the membrane module housing from the inside of the membrane tube to obtain a second clear liquid. The second clear liquid enters the clear liquid outlet pipeline on the housing side and is discharged from the membrane filter through the second clear liquid outlet of the membrane filter.

[0108] In some preferred embodiments of the present invention, a backwashing line is provided on the clarified liquid discharge line for backwashing the membrane tube. In the present invention, the medium for the backwashing operation can be a second clarified liquid and / or water, preferably the second clarified liquid.

[0109] In some preferred embodiments of the present invention, the filtration accuracy of the membrane tube in the membrane filter is 0.01-50 μm, preferably 0.05-10 μm. Using the above preferred embodiments facilitates the effective separation of the clarified liquid.

[0110] In this invention, the material of the membrane tube in the membrane filter is not particularly limited and can be any material commonly used in membrane filters in the art. Preferably, the material of the membrane tube in the membrane filter is selected from at least one of ceramic, metal, and high-density polyethylene, preferably ceramic and / or metal, and more preferably metal.

[0111] In some preferred embodiments of the present invention, the method further includes: heating the catalyst-rich stream obtained in step (4).

[0112] In some preferred embodiments of the present invention, the method further includes: (5) extracting the first clear liquid and / or the second clear liquid with the organic solvent obtained in step (3) to separate the aqueous phase and the organic phase, and returning the extracted organic phase to step (2) to provide at least a portion of the organic solvent.

[0113] In this invention, the extraction method in step (5) is not particularly limited. Preferably, the extraction method is countercurrent extraction.

[0114] In some preferred embodiments of the present invention, the extraction temperature is 30-90°C, preferably 40-80°C. Using these preferred embodiments facilitates a highly efficient extraction process and ensures the stability of the reaction product and the extractant.

[0115] In some preferred embodiments of the present invention, the organic solvent obtained in step (3) is used to extract the first clear liquid and / or the second clear liquid to obtain an organic phase and an aqueous phase.

[0116] In this invention, the aqueous phase obtained by extraction in step (5) contains a small amount of ammonia. Preferably, step (5) further includes: removing ammonia from the aqueous phase obtained by extraction to obtain ammonia water and wastewater; and returning the obtained ammonia water to the ammonia oxime reaction in step (1).

[0117] In some particularly preferred embodiments of the present invention, the carbonyl compound is cyclohexanone, and in step (1), based on the total amount of the carbonyl compound and the circulating catalyst slurry, the mass fraction of the carbonyl compound is 2-8%, for example, it can be a specific and non-limiting value or any range between 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 5.5%, 6%, 6.5%, 7%, 7.5%, 8%, etc., preferably 3-6%. Using the above preferred embodiments is beneficial for extending the service life of the catalyst, reducing catalyst consumption, and improving the quality of the oxime product.

[0118] In some embodiments of the present invention, the mass fraction of the carbonyl compound can be made to meet the above-mentioned range by adjusting the feed ratio of the carbonyl compound and the circulating catalyst slurry.

[0119] A second aspect of the present invention provides a system for preparing oximes, the system comprising a reaction unit, an optional water washing unit, an optional extraction unit, and an optional product separation unit, the reaction unit comprising at least one reactor, a catalyst separator, and a filter;

[0120] The reactor is connected to a circulating catalyst slurry pipeline and a hydrogen peroxide feed pipeline, respectively. The circulating catalyst slurry pipeline is provided with a carbonyl compound inlet and an ammonia inlet. The reactor is used to contact the mixed flow containing carbonyl compounds, ammonia and circulating catalyst slurry from the circulating catalyst slurry pipeline with hydrogen peroxide from the hydrogen peroxide feed pipeline to carry out an ammonium oxime reaction.

[0121] The reactor and the catalyst separator are connected by a pipeline, which is provided with an organic solvent inlet; the catalyst separator is provided with an aqueous phase outlet and an organic phase outlet, for separating the mixed extract stream containing the reaction slurry from the reactor and the organic solvent into two phases.

[0122] The organic phase outlet of the catalyst separator is connected to the optional product separation unit via the optional water washing unit, and the aqueous phase outlet of the catalyst separator is connected to the reactor via the filter and the circulating catalyst slurry pipeline;

[0123] The product separation unit is used to separate the organic phase from the catalyst separator to obtain organic solvents and oxime products.

[0124] In some preferred embodiments of the present invention, the reaction unit further includes a heat extractor.

[0125] In some preferred embodiments of the present invention, the heat extractor is disposed on a pipeline between the reactor and the catalyst separator for heat extraction of the reaction slurry before or after mixing with the organic solvent.

[0126] In some other preferred embodiments of the present invention, the reaction slurry outlet of the reactor is connected to the catalyst separator and the heat exchanger respectively, for sending part of the reaction slurry into the catalyst separator and returning the remaining part of the reaction slurry to the reactor after heat extraction by the heat exchanger.

[0127] In some preferred embodiments of the present invention, the system includes a carbonyl compound feed line and an ammonia feed line, each independently connected to a carbonyl compound inlet and an ammonia inlet on a circulating catalyst slurry line, for supplying a mixture of carbonyl compound, ammonia and circulating catalyst slurry to the reactor.

[0128] In some preferred embodiments of the present invention, the system includes a water washing unit and an extraction unit, wherein the water washing unit is provided with an aqueous phase outlet and an oxime-rich organic phase outlet.

[0129] In some preferred embodiments of the present invention, the organic phase outlet of the catalyst separator is connected to the water washing unit, the aqueous phase outlet of the water washing unit is connected to the aqueous phase inlet of the extraction unit, the oxime-rich organic phase outlet of the water washing unit is connected to the inlet of the product separation unit, and the water washing unit is used to wash the organic phase from the catalyst separator.

[0130] In some preferred embodiments of the present invention, the organic solvent outlet of the product separation unit is connected to the organic solvent inlet of the extraction unit, and the product separation unit is used to separate the oxime-rich organic phase from the water washing unit to obtain the oxime product and the organic solvent leading to the extraction unit.

[0131] In some preferred embodiments of the present invention, the filter is a membrane filter disposed in the aqueous phase section of the catalyst separator or connected to the aqueous phase outlet of the catalyst separator. The membrane filter has a catalyst-rich stream outlet and a clear liquid outlet. The catalyst-rich stream outlet is connected to the reactor through the circulating catalyst slurry pipeline, and the second clear liquid outlet is connected to the aqueous phase inlet of the extraction unit. The membrane filter is used to filter the aqueous phase from the catalyst separator to obtain a catalyst-rich stream and a second clear liquid. The catalyst-rich stream is sent into the reactor, and the second clear liquid is sent into the extraction unit.

[0132] In some preferred embodiments of the present invention, the extraction unit includes at least one extraction tower, and the organic solvent outlet of the extraction unit is connected via an organic solvent pipeline to an organic solvent inlet on a pipeline between the reactor and the catalyst separator, specifically, to a pipeline between the reactor and the heat exchanger or to a pipeline between the heat exchanger and the catalyst separator. The extraction unit is used to extract a first clear liquid from the water washing unit and / or a second clear liquid from the membrane filter using an organic solvent from the product separation unit.

[0133] In this invention, the number of reactors in the reaction unit is not particularly limited. Those skilled in the art can select and set one or more reactors according to actual production needs, and two or more reactors can be connected in series and / or in parallel. Preferably, the number of reactors is 1-4, more preferably 1-2.

[0134] In some embodiments of the invention, the reactor is as described in the first aspect.

[0135] In this invention, when multiple reactors are connected in series and / or in parallel, preferably each reactor is independently connected to a hydrogen peroxide feed line so that hydrogen peroxide can be fed into multiple reactors simultaneously.

[0136] In some preferred embodiments of the present invention, the catalyst separator includes a vessel body and a stirrer, an inner extension tube, and an inner sleeve disposed within the vessel body; the inner sleeve is fitted inside the inner extension tube and is used to convey a mixed extractant stream containing a reaction slurry and an organic solvent to the inner extension tube; the inner extension tube is used to convey the mixed extractant stream containing a reaction slurry and an organic solvent to the vessel body for two-phase separation to obtain an organic phase and an aqueous phase; a gas phase balance port is provided on the side wall of the inner extension tube to maintain the gas phase balance of the vessel body; the stirring paddle of the stirrer is disposed in the aqueous phase section of the vessel body to stir the aqueous phase.

[0137] In some preferred embodiments of the present invention, the top end of the inner tube is located outside the vessel body, and the bottom end of the inner tube is located inside the vessel body.

[0138] In some preferred embodiments of the present invention, the top end of the inner sleeve is flush with the top end of the inner extension tube, and the top of the annular space formed by the inner sleeve and the inner extension tube is closed.

[0139] In some preferred embodiments of the present invention, the bottom end of the inner tube is provided with an anti-impact baffle for buffering the mixed extract stream containing the reaction slurry obtained from the ammonium oxime reaction and the organic solvent.

[0140] In some preferred embodiments of the present invention, an overflow weir is provided at the upper part of the vessel body for overflowing the organic phase to obtain the organic phase product.

[0141] In some preferred embodiments of the present invention, an organic phase outlet is provided at the upper part of the vessel body, and the organic phase outlet is connected to the overflow weir.

[0142] In some preferred embodiments of the present invention, the bottom of the vessel is provided with an aqueous phase outlet and an optional clear liquid outlet.

[0143] In some preferred embodiments of the present invention, a gas phase outlet is provided at the top of the vessel.

[0144] In some preferred embodiments of the present invention, the gas phase balance port is directly connected to the gas phase space above the vessel body, or the gas phase balance port is connected to the gas phase space above the vessel body through a pipeline.

[0145] In some embodiments of the invention, the catalyst separator is as described in the first aspect.

[0146] In some preferred embodiments of the present invention, the membrane filter comprises at least one membrane module. When the membrane filter includes two or more membrane modules, the membrane modules may be connected in parallel and / or in series.

[0147] In some preferred embodiments of the present invention, when the membrane filter is installed in the aqueous phase section of the catalyst separator, each membrane module consists of a membrane tube and a manifold; when the membrane filter is installed downstream of the catalyst separator, each membrane module consists of a housing, a tube sheet, end caps and a membrane tube, with the membrane tube placed inside the housing and tube sheets at both ends of the membrane tube for separating the flow streams inside and outside the membrane tube.

[0148] In some preferred embodiments of the present invention, the filtration accuracy of the membrane tube in the membrane filter is 0.01-50 μm, preferably 0.05-10 μm.

[0149] In some preferred embodiments of the present invention, the material of the membrane tube is not particularly limited and can be any material commonly used in membrane filters. Preferably, the material of the membrane tube in the membrane filter is selected from at least one of ceramic, metal, and high-density polyethylene, more preferably ceramic and / or metal, and more preferably metal.

[0150] In some preferred embodiments of the present invention, a heat exchanger is provided on the circulating catalyst slurry pipeline between the membrane filter and the reactor.

[0151] In some embodiments of the invention, the membrane filter is as described in the first aspect.

[0152] In some preferred embodiments of the present invention, the system further includes an ammonia removal unit connected to the aqueous phase outlet of the extraction unit, for removing ammonia from the aqueous phase from the extraction unit to obtain ammonia water and wastewater. In some preferred embodiments of the present invention, the obtained wastewater is sent to the next process.

[0153] In some preferred embodiments of the present invention, the circulating catalyst slurry pipeline is further provided with a circulating ammonia water inlet, and the ammonia water outlet of the deammoniation unit is connected to the circulating ammonia water inlet on the circulating catalyst slurry pipeline for returning ammonia water to the reactor.

[0154] In some embodiments of the present invention, the circulating catalyst slurry pipeline is configured such that the feed ratio of the carbonyl compound to the circulating catalyst slurry, by mass, is 1:10-50, preferably 1:15-30. For example, a delivery pump can be installed on the circulating catalyst slurry pipeline to control the feed flow rate of the circulating catalyst slurry.

[0155] In some preferred embodiments of the present invention, the system further includes a tail gas absorption unit, wherein the gas phase outlet of the reactor is connected to the tail gas absorption unit, and the liquid phase outlet of the tail gas absorption unit is connected to the reactor, for contacting the gas generated in the reaction with demineralized water to remove ammonia, and the resulting absorbent is returned to the reactor. In some embodiments of the present invention, the ammonia-removed gas is sent to the next process.

[0156] In some embodiments of the present invention, the system for preparing oxime according to the second aspect is a system for implementing the method for preparing oxime according to the first aspect.

[0157] In some embodiments of the present invention, as shown in FIG1, the system includes a reaction unit, a water washing unit 6, a product separation unit 7 and an extraction unit 8. The reaction unit includes a reactor 1, a heat extractor 2, a catalyst separator 3 and a membrane filter 4.

[0158] Reactor 1 is connected to the circulating catalyst slurry pipeline 10 and the hydrogen peroxide feed pipeline respectively. The circulating catalyst slurry pipeline 10 is provided with a carbonyl compound inlet and an ammonia inlet. Reactor 1 is used to contact the mixed flow containing carbonyl compounds, ammonia and circulating catalyst slurry from the circulating catalyst slurry pipeline 10 with hydrogen peroxide from the hydrogen peroxide feed pipeline to carry out an ammonium oxime reaction.

[0159] Reactor 1 and catalyst separator 3 are connected by a pipeline. A heat exchanger 2 is provided on the pipeline between reactor 1 and catalyst separator 3. The pipeline has a circulating organic solvent inlet 11 upstream of the heat exchanger 2 (or downstream of the heat exchanger 2 in another embodiment). The catalyst separator 3 is used to perform two-phase separation of the mixed extract stream containing the reaction slurry from reactor 1 and organic solvent.

[0160] The organic phase outlet of the catalyst separator 3 is connected to the water washing unit 6, the aqueous phase outlet of the water washing unit 6 is connected to the aqueous phase inlet of the extraction unit 8, and the oxime-rich organic phase outlet of the water washing unit 6 is connected to the inlet of the product separation unit 7. The water washing unit 6 is used to wash the organic phase from the catalyst separator 3.

[0161] The organic solvent outlet of the product separation unit 7 is connected to the organic solvent inlet of the extraction unit 8. The product separation unit 7 is used to separate the oxime-rich stream from the water washing unit 6.

[0162] The inlet of the membrane filter 4 is connected to the aqueous phase outlet of the catalyst separator 3. The catalyst-rich stream outlet of the membrane filter 4 is connected to the reactor 1 through the circulating catalyst slurry pipeline 10. The second clear liquid outlet of the membrane filter 4 is connected to the aqueous phase inlet of the extraction unit 8. The membrane filter 4 is used to filter the aqueous phase from the catalyst separator 3 to obtain the catalyst-rich stream and the second clear liquid. The catalyst-rich stream is sent to the reactor 1 and the second clear liquid is sent to the extraction unit 8.

[0163] The organic solvent outlet of the extraction unit 8 is connected to the pipeline between the reactor 1 and the heat exchanger 2 via the organic solvent pipeline 11 (or, in another embodiment, to the pipeline between the heat exchanger 2 and the catalyst separator 3). The extraction unit 8 is used to extract the first clear liquid from the water washing unit 6 and / or the second clear liquid from the membrane filter 4 using the organic solvent from the product separation unit 7.

[0164] The system also includes an ammonia removal unit 9 connected to the aqueous phase outlet of the extraction unit 8, for separating wastewater and ammonia from the aqueous phase.

[0165] In some other embodiments of the present invention, as shown in FIG2, unlike the embodiment according to FIG1, the reaction slurry outlet of reactor 1 is connected to catalyst separator 3 and heat exchanger 2 respectively, for sending part of the reaction slurry into catalyst separator 3, and returning the remaining part of the reaction slurry to reactor 1 after being heated by heat exchanger 2; catalyst separator 3 is used to perform two-phase separation of the mixed extract stream of part of the reaction slurry from reactor 1 and organic solvent; the organic solvent outlet of extraction unit 8 is connected to the pipeline between the reaction slurry outlet of reactor 1 and catalyst separator 3 through organic solvent pipeline 11.

[0166] In some embodiments of the present invention, the catalyst separator is a separation device as shown in FIG. 3. The separation device includes a vessel body 1 and a stirrer 2, an inner extension tube 3, and an inner sleeve 5 disposed in the vessel body 1. The top end of the inner extension tube 3 is located outside the vessel body 1, and the bottom end of the inner extension tube 3 is located inside the vessel body 1. The ratio of the length of the inner extension tube 3 extending below the upper tangent of the vessel body 1 to the vertical distance between the upper and lower tangents of the vessel body 1 is, for example, 0.85:1. The inner sleeve 5 is sleeved inside the inner extension tube 3, and the top end of the inner sleeve 5 is flush with the top end of the inner extension tube 3. The top of the annular space formed by the inner sleeve 5 and the inner extension tube 3 is... The inner tube 3 and the inner sleeve 5 are enclosed, and the length ratio is, for example, 15:1. A gas phase balance port 10 is provided on the side wall of the inner tube 3, and the gas phase balance port 10 is connected to the gas phase space of the vessel body 1 to ensure gas phase balance. The stirring paddle (specifically a turbine paddle) of the stirrer 2 is located at the bottom of the vessel body 1, and the stirring paddle has one layer. An anti-impact baffle 4 is provided at the bottom end of the inner tube 3. An overflow weir 6 (the overflow weir 6 is an L-shaped plate, one end of which is connected to the inner wall of the vessel body 1) and an organic phase outlet 7 connected to the overflow weir 6 are also provided in the vessel body 1. A water phase outlet 8 is provided at the bottom of the vessel body 1, and a gas phase outlet 9 is provided at the top of the vessel body 1.

[0167] In some embodiments of the present invention, a mixed extract stream comprising a reaction slurry and an organic solvent is conveyed through an inner sleeve 5 to an inner extension pipe 3, and then through the inner extension pipe 3 and an anti-impact baffle 4 to a vessel body 1. The mixed extract stream undergoes two-phase separation in the vessel body 1 to obtain an oxime-containing organic phase and a catalyst-containing aqueous phase. The organic phase is conveyed through an overflow weir 6 from the organic phase outlet 7 to the next process, such as a water washing unit. The aqueous phase is conveyed through the aqueous phase outlet 8 under the action of the agitator 2 to the next process, such as a filter.

[0168] In some other embodiments of the present invention, the catalyst separator is the separation device shown in FIG. 4. Unlike the separation device shown in FIG. 3, the separation device shown in FIG. 4 has a membrane module 11 (membrane module 11 includes, for example, 24 membrane tubes connected in parallel) installed below the height of the anti-surge baffle 4. One end of the membrane tube is closed, and the other end is connected to the collecting pipe 12. The collecting pipe 12 is connected to the clear liquid outlet 13. The liquid in the aqueous phase permeates from the outer surface of the membrane tube to the inner side of the membrane tube to obtain clear liquid. The clear liquid in different membrane tubes is collected by the collecting pipe 12 and discharged. A backwashing line is provided on the clear liquid discharge line, and the backwash liquid is the filtered clear liquid. The membrane tube is made of 316 stainless steel and the filtration accuracy is 0.2μm.

[0169] In some embodiments of the present invention, a mixed extract stream comprising a reaction slurry and an organic solvent is conveyed through an inner sleeve 5 to an inner extension tube 3, and then through the inner extension tube 3 and an anti-impact baffle 4 to a vessel body 1. The mixed extract stream undergoes two-phase separation in the vessel body 1 to obtain an oxime-containing organic phase and a catalyst-containing aqueous phase. The organic phase is conveyed through an overflow weir 6 from the organic phase outlet 7 to the next process, such as a water washing unit. A portion of the liquid in the aqueous phase permeates from the outer surface of the membrane tube to the inner surface, and the resulting clarified liquid is discharged through a collecting pipe 12 and a clarified liquid outlet 13. The filtered aqueous phase is then conveyed through the aqueous phase outlet 8 under the action of the agitator 2 to the next process, such as a filter.

[0170] The present invention discloses the following embodiments:

[0171] Option 1: A method for preparing cyclohexanone oxime, characterized in that the method includes the following steps:

[0172] (1) Cyclohexanone, ammonia and recycled catalyst slurry are mixed, and then the mixture is contacted with hydrogen peroxide to carry out an ammonium oxime reaction to obtain a reaction slurry;

[0173] Based on the total amount of cyclohexanone and the circulating catalyst slurry, the mass fraction of cyclohexanone is 2-6%;

[0174] (2) The reaction slurry is mixed with an organic solvent and the two phases are separated to obtain an organic phase containing cyclohexanone oxime and an aqueous phase containing a catalyst.

[0175] The method further includes: heating the reaction slurry before mixing it with the organic solvent; or heating the mixture of the reaction slurry and the organic solvent before performing two-phase separation.

[0176] The mass ratio of organic solvent to cyclohexanone oxime in the reaction slurry is 0.5-5:1;

[0177] (3) The organic phase obtained in step (2) is washed with water to obtain a stream rich in cyclohexanone oxime and a first supernatant. Then the stream rich in cyclohexanone oxime is separated to obtain an organic solvent and a cyclohexanone oxime product.

[0178] (4) The aqueous phase obtained in step (2) is filtered by membrane to obtain a catalyst-rich stream and a second clear liquid; the obtained catalyst-rich stream is returned to step (1) to provide circulating catalyst slurry;

[0179] (5) Extract the first clear liquid and / or the second clear liquid using the organic solvent obtained in step (3), and return the resulting organic phase to step (2) to provide the organic solvent.

[0180] Option 2: According to the method described in Option 1, wherein the mass ratio of the cyclohexanone to the circulating catalyst slurry is 1:15-50, preferably 1:16-32;

[0181] Preferably, the mass fraction of cyclohexanone is 3-5.5%, based on the total amount of cyclohexanone and the circulating catalyst slurry;

[0182] Preferably, the mass fraction of cyclohexanone oxime in the circulating catalyst slurry is 0.1-4%, more preferably 0.5-3%;

[0183] Preferably, the mass ratio of the organic solvent to the cyclohexanone oxime in the reaction slurry is 1-3:1.

[0184] Scheme 3: The method according to Scheme 1 or 2, wherein the molar ratio of hydrogen peroxide to cyclohexanone in the ammonium oxime reaction system is 1-1.5:1, preferably 1-1.3:1;

[0185] Preferably, the hydrogen peroxide is provided by hydrogen peroxide solution, wherein the mass concentration of hydrogen peroxide in the hydrogen peroxide solution is 15-80 wt%, preferably 20-70 wt%.

[0186] Preferably, in the ammonium oxime reaction system, the molar ratio of ammonia to cyclohexanone is 1-1.5:1, more preferably 1-1.3:1;

[0187] Preferably, the mass fraction of the catalyst in the circulating catalyst slurry is 0.1%-15%, more preferably 1%-10%;

[0188] Preferably, the catalyst comprises a titanium-silicon molecular sieve, wherein the titanium-silicon molecular sieve is selected from at least one of TS-1, TS-2, Ti-ZSM-5, Ti-ZSM-12, Ti-ZSM-48, Ti-β, Ti-MCM-41, Ti-MOR, Ti-MWW and Ti-SBA-15;

[0189] Preferably, the organic solvent is selected from at least one of alkanes having 6-12 carbon atoms, cycloalkanes having 5-11 carbon atoms, and aromatics having 6-10 carbon atoms, more preferably from at least one of aromatics having 6-10 carbon atoms and cycloalkanes having 6-10 carbon atoms, and more preferably from toluene and / or cyclohexane.

[0190] Option 4: The method described in any one of Options 1-3, wherein the conditions for the ammonium oxime reaction include: a reaction temperature of 70-100℃, preferably 80-95℃; and a reaction pressure of 0-0.5 MPaG, preferably 0.2-0.4 MPaG.

[0191] Preferably, the ammonium oxime reaction is carried out in a stirred tank reactor;

[0192] Preferably, the method in step (1) further includes: contacting the gas generated by the ammonium oximation reaction with demineralized water to remove ammonia, and returning the resulting absorbent to the ammonium oximation reaction in step (1).

[0193] Option 5: The method according to any one of Options 1-4, wherein the method further includes: optionally heating the catalyst-rich stream obtained by membrane filtration;

[0194] Preferably, in step (2), after heat treatment, the temperature of the reaction slurry and / or the mixture of the reaction slurry and the organic solvent is 40-85°C.

[0195] Scheme 6: The method according to any one of Schemes 1-5, wherein the two-phase separation in step (2) is carried out in a catalyst separator; the catalyst separator includes a vessel body and a stirrer, an inner extension tube and an inner sleeve disposed in the vessel body; the inner sleeve is sleeved inside the inner extension tube, and a gas phase balance port is opened on the side wall of the inner extension tube; the stirring paddle of the stirrer is disposed in the aqueous phase section of the vessel body for stirring the aqueous phase;

[0196] Preferably, the top end of the inner tube is located outside the vessel body, and the bottom end of the inner tube is located inside the vessel body;

[0197] Preferably, the top end of the inner sleeve is flush with the top end of the inner extension tube, and the top of the annular space formed by the inner sleeve and the inner extension tube is closed.

[0198] Preferably, an anti-impact baffle is provided at the bottom end of the inner tube;

[0199] Preferably, the conditions for the two-phase separation in step (2) include: pressure of 0-500 kPaG and temperature of 40-90℃;

[0200] Preferably, the separation conditions in step (3) include: pressure of 0-500 kPaG and temperature of 40-90℃;

[0201] Preferably, the water washing stage in step (3) is 1-5 stages, and more preferably 1-3 stages.

[0202] Scheme 7: The method according to any one of Schemes 1-6, wherein the membrane filtration in step (4) is carried out in a membrane filter, and the membrane filter is set inside the catalyst separator or connected to the aqueous phase outlet of the catalyst separator;

[0203] Preferably, the filtration accuracy of the membrane tube in the membrane filter is 0.01-50 μm, and more preferably 0.05-10 μm;

[0204] Preferably, the membrane tube in the membrane filter is made of at least one of ceramic, metal and high-density polyethylene, preferably ceramic and / or metal, and more preferably metal;

[0205] Preferably, the extraction method in step (5) is countercurrent extraction;

[0206] Preferably, the extraction temperature is 30-90℃, and more preferably 40-80℃;

[0207] Preferably, the method in step (5) further includes: removing ammonia from the aqueous phase obtained by extraction to obtain ammonia water and wastewater; and returning the obtained ammonia water to the ammonia oxime reaction in step (1).

[0208] Option 8: A system for preparing cyclohexanone oxime, characterized in that the system includes a reaction unit, a water washing unit, an extraction unit and a product separation unit, wherein the reaction unit includes at least one reactor, a catalyst separator, a reaction heat exchanger and a membrane filter disposed inside the catalyst separator or connected to the aqueous phase outlet of the catalyst separator.

[0209] The reactor is connected to the circulating catalyst slurry pipeline and the hydrogen peroxide feed pipeline, respectively. The circulating catalyst slurry pipeline is equipped with a cyclohexanone inlet and an ammonia inlet. The reactor is used to contact the cyclohexanone, ammonia and circulating catalyst slurry mixture from the circulating catalyst slurry pipeline with hydrogen peroxide from the hydrogen peroxide feed pipeline to carry out an ammonoximation reaction.

[0210] The reactor and the catalyst separator are connected by a pipeline. A reaction heat exchanger is installed on the pipeline between the reactor and the catalyst separator. The pipeline is equipped with a circulating organic solvent inlet. The catalyst separator is used to separate the reaction slurry from the reactor and the mixed extract material of the organic solvent into two phases.

[0211] The organic phase outlet of the catalyst separator is connected to the water washing unit, the aqueous phase outlet of the water washing unit is connected to the aqueous phase inlet of the extraction unit, and the cyclohexanone oxime-rich outlet of the water washing unit is connected to the cyclohexanone oxime-rich inlet of the product separation unit. The water washing unit is used to wash the organic phase from the catalyst separator.

[0212] The product separation unit's organic solvent outlet is connected to the extraction unit's organic solvent inlet. The product separation unit is used to separate the material rich in cyclohexanone oxime from the water washing unit.

[0213] The catalyst-rich stream outlet of the membrane filter is connected to the reactor via a circulating catalyst slurry pipeline, and the second clear liquid outlet of the membrane filter is connected to the aqueous phase inlet of the extraction unit. The membrane filter is used to filter the aqueous phase separated from the two phases of the catalyst separator, and to send the catalyst-rich stream into the reactor and the second clear liquid into the extraction unit.

[0214] An extraction unit includes at least one extraction tower. The organic solvent outlet of the extraction unit is connected to a pipeline between the reactor and the reaction heat exchanger via a circulating organic solvent pipeline, or to a pipeline between the reaction heat exchanger and the catalyst separator. The extraction unit is used to extract the first clear liquid from the water washing unit and / or the second clear liquid from the membrane filter using the organic solvent from the product separation unit.

[0215] Option 9: The reaction system according to Option 8, wherein the reaction unit includes 1-4 reactors, preferably 1-2 reactors;

[0216] Preferably, the reactor is a stirred tank reactor;

[0217] Preferably, each reactor is independently connected to a hydrogen peroxide feed line;

[0218] Preferably, the catalyst separator includes a vessel body and a stirrer, an inner extension tube, and an inner sleeve disposed within the vessel body; the inner sleeve is fitted inside the inner extension tube and is used to convey the mixed extract material of the reaction slurry and organic solvent to the inner extension tube; the inner extension tube is used to convey the mixed extract material of the reaction slurry and organic solvent to the vessel body for two-phase separation to obtain an organic phase and an aqueous phase; a gas phase balance port is provided on the side wall of the inner extension tube to maintain the gas phase balance of the vessel body; the stirring paddle of the stirrer is disposed in the aqueous phase section of the vessel body to stir the aqueous phase;

[0219] Preferably, the top end of the inner tube is located outside the vessel body, and the bottom end of the inner tube is located inside the vessel body;

[0220] Preferably, the top end of the inner sleeve is flush with the top end of the inner extension tube, and the top of the annular space formed by the inner sleeve and the inner extension tube is closed.

[0221] Preferably, the bottom end of the inner tube is provided with an anti-impact baffle to buffer the mixed extraction material of the reaction slurry and organic solvent;

[0222] Preferably, the filtration accuracy of the membrane tube in the membrane filter is 0.01-50 μm, and more preferably 0.05-10 μm;

[0223] Preferably, the membrane tube in the membrane filter is made of at least one of ceramic, metal and high-density polyethylene, preferably ceramic and / or metal, and more preferably metal.

[0224] Option 10: The reaction system according to Option 9, wherein a heat exchanger is optionally provided on the circulating catalyst slurry pipeline between the membrane filter and the reactor;

[0225] Preferably, the system further includes an ammonia removal unit connected to the aqueous phase outlet of the extraction unit for separating wastewater and ammonia from the aqueous phase;

[0226] Preferably, the circulating catalyst slurry pipeline is further provided with a circulating ammonia water inlet, and the ammonia water outlet of the deammoniation unit is connected to the circulating ammonia water inlet on the circulating catalyst slurry pipeline for returning ammonia water to the ammonium oxime reaction;

[0227] Preferably, the system further includes a tail gas absorption unit, with the gas phase outlet of the reactor connected to the tail gas absorption unit and the liquid phase outlet of the tail gas absorption unit connected to the reactor, for contacting the gas generated by the reaction with demineralized water to remove ammonia.

[0228] The present invention also discloses the following embodiments:

[0229] Option 1: A method for preparing cyclohexanone oxime, characterized in that the method comprises:

[0230] (1) Cyclohexanone, ammonia and circulating catalyst slurry are mixed, and then the mixture is contacted with hydrogen peroxide to carry out an ammonium oxime reaction to obtain a reaction slurry;

[0231] Based on the total amount of cyclohexanone and the circulating catalyst slurry, the mass fraction of cyclohexanone is 2-6%;

[0232] (2) A portion of the reaction slurry is mixed with an organic solvent for two-phase separation to obtain an organic phase containing cyclohexanone oxime and an aqueous phase containing a catalyst; the remaining portion of the reaction slurry is returned to the ammonium oxime reaction in step (1) after being heated.

[0233] The mass ratio of organic solvent to cyclohexanone oxime in part of the reaction slurry is 0.5-5:1;

[0234] (3) The organic phase obtained in step (2) is washed with water to obtain a stream rich in cyclohexanone oxime and a first supernatant. Then the stream rich in cyclohexanone oxime is separated to obtain an organic solvent and a cyclohexanone oxime product.

[0235] (4) The aqueous phase obtained in step (2) is filtered by membrane to obtain a catalyst-rich stream and a second clear liquid; the obtained catalyst-rich stream is returned to step (1) to provide circulating catalyst slurry;

[0236] (5) Extract the first clear liquid and / or the second clear liquid using the organic solvent obtained in step (3), and return the resulting organic phase to step (2) to provide the organic solvent.

[0237] Option 2: According to the method described in Option 1, wherein the mass fraction of cyclohexanone oxime in the circulating catalyst slurry is 0.1-4%, preferably 0.5-3%;

[0238] Preferably, the mass ratio of the organic solvent to the cyclohexanone oxime in a portion of the reaction slurry is 1-3:1;

[0239] Preferably, the mass fraction of cyclohexanone is 3-5.5%, based on the total amount of cyclohexanone and the circulating catalyst slurry;

[0240] Preferably, the mass ratio of the cyclohexanone to the circulating catalyst slurry is 1:15-50, and more preferably 1:16-32.

[0241] Scheme 3: The method according to Scheme 1 or 2, wherein the molar ratio of hydrogen peroxide to cyclohexanone in the ammonium oxime reaction system is 1-1.5:1, preferably 1-1.3:1;

[0242] Preferably, in the ammonium oxime reaction system, the molar ratio of ammonia to cyclohexanone is 1-1.5:1, more preferably 1-1.3:1;

[0243] Preferably, the catalyst comprises a titanium-silicon molecular sieve, wherein the titanium-silicon molecular sieve is selected from at least one of TS-1, TS-2, Ti-ZSM-5, Ti-ZSM-12, Ti-ZSM-48, Ti-β, Ti-MCM-41, Ti-MOR, Ti-MWW and Ti-SBA-15;

[0244] Preferably, the mass fraction of the catalyst in the circulating catalyst slurry is 0.1%-15%, more preferably 1%-10%;

[0245] Preferably, the organic solvent is selected from at least one of alkanes having 6-12 carbon atoms, cycloalkanes having 5-11 carbon atoms, and aromatics having 6-10 carbon atoms, more preferably from at least one of aromatics having 6-10 carbon atoms and cycloalkanes having 6-10 carbon atoms, and more preferably from toluene and / or cyclohexane.

[0246] Scheme 4: The method described in any one of Schemes 1-3, wherein the conditions for the ammonium oxime reaction in step (1) include: a reaction temperature of 70-100℃, preferably 80-95℃; and a reaction pressure of 0-0.5 MPaG, preferably 0.2-0.4 MPaG.

[0247] Preferably, the ammonium oxime reaction in step (1) is carried out in a stirred tank reactor;

[0248] Preferably, the circulating catalyst slurry comprises the catalyst-rich stream obtained in step (4) and optionally a slurry containing fresh catalyst.

[0249] Scheme 5: The method described in any one of Schemes 1-4, wherein in step (2), the mass ratio of the partial reaction slurry to the remaining partial reaction slurry is 1:2-8, preferably 1:3-5.

[0250] Scheme 6: The method according to any one of Schemes 1-5, wherein the two-phase separation in step (2) is carried out in a catalyst separator; the catalyst separator includes a vessel body and a stirrer, an inner extension tube and an inner sleeve disposed in the vessel body; the inner sleeve is sleeved inside the inner extension tube, and a gas phase balance port is opened on the side wall of the inner extension tube; the stirring paddle of the stirrer is disposed in the aqueous phase section of the vessel body for stirring the aqueous phase;

[0251] Preferably, the top end of the inner tube is located outside the vessel body, and the bottom end of the inner tube is located inside the vessel body;

[0252] Preferably, the top end of the inner sleeve is flush with the top end of the inner extension tube, and the top of the annular space formed by the inner sleeve and the inner extension tube is closed.

[0253] Preferably, an anti-impact baffle is provided at the bottom end of the inner tube;

[0254] Preferably, the membrane filtration in step (4) is carried out in a membrane filter, which is located inside the catalyst separator vessel or connected to the aqueous phase outlet of the catalyst separator.

[0255] Preferably, the filtration accuracy of the membrane tube in the membrane filter is 0.01-50 μm, and more preferably 0.05-10 μm;

[0256] Preferably, the membrane tube in the membrane filter is made of at least one of ceramic, metal and high-density polyethylene, preferably ceramic and / or metal, and more preferably metal;

[0257] Preferably, the conditions for the two-phase separation in step (2) include: pressure of 0-500 kPaG and temperature of 40-90℃;

[0258] Preferably, the separation conditions in step (3) include: pressure of 0-500 kPaG and temperature of 40-90℃;

[0259] Preferably, the water washing stage in step (3) is 1-5 stages, and more preferably 1-3 stages;

[0260] Preferably, the extraction method in step (5) is countercurrent extraction;

[0261] Preferably, the extraction temperature is 30-90℃, and more preferably 40-80℃.

[0262] Scheme 7: According to the method described in Scheme 6, wherein the method in step (5) further includes: removing ammonia from the aqueous phase obtained by extraction to obtain ammonia water and wastewater; returning the obtained ammonia water to the ammonium oxime reaction in step (1);

[0263] Preferably, the method in step (1) further includes: contacting the gas generated by the ammonium oximation reaction with demineralized water to absorb the ammonia in the gas, and returning the resulting absorbent to the ammonium oximation reaction.

[0264] Option 8: A system for preparing cyclohexanone oxime, characterized in that the system includes a reaction unit, a water washing unit, an extraction unit and a product separation unit, wherein the reaction unit includes at least one reactor, a catalyst separator, a reaction heat exchanger and a membrane filter disposed inside the catalyst separator or connected to the aqueous phase outlet of the catalyst separator;

[0265] The reactor is connected to the circulating catalyst slurry pipeline and the hydrogen peroxide feed pipeline, respectively. The circulating catalyst slurry pipeline is equipped with a cyclohexanone inlet and an ammonia inlet. The reactor is used to contact the cyclohexanone, ammonia and circulating catalyst slurry mixture from the circulating catalyst slurry pipeline with hydrogen peroxide from the hydrogen peroxide feed pipeline to carry out an ammonoximation reaction.

[0266] The reactor's reaction slurry outlet is connected to a catalyst separator and a heat exchanger, respectively. The catalyst separator is used to send part of the reaction slurry into the catalyst separator and return the remaining reaction slurry to the reactor after heat extraction by the heat exchanger. The catalyst separator is used to separate the part of the reaction slurry from the reactor from the mixed extract of organic solvents into two phases.

[0267] The organic phase outlet of the catalyst separator is connected to the water washing unit, the aqueous phase outlet of the water washing unit is connected to the aqueous phase inlet of the extraction unit, and the cyclohexanone oxime-rich outlet of the water washing unit is connected to the cyclohexanone oxime-rich inlet of the product separation unit. The water washing unit is used to wash the organic phase from the catalyst separator.

[0268] The product separation unit's organic solvent outlet is connected to the extraction unit's organic solvent inlet. The product separation unit is used to separate the material rich in cyclohexanone oxime from the water washing unit.

[0269] The catalyst-rich stream outlet of the membrane filter is connected to the reactor via a circulating catalyst slurry pipeline, and the second clear liquid outlet of the membrane filter is connected to the aqueous phase inlet of the extraction unit. The membrane filter is used to filter the aqueous phase separated from the two phases of the catalyst separator, and the resulting catalyst-rich stream is sent to the reactor and the second clear liquid is sent to the extraction unit.

[0270] An extraction unit includes at least one extraction tower. The organic solvent outlet of the extraction unit is connected to a pipeline between the reaction slurry outlet and the catalyst separator via a circulating organic solvent pipeline. The extraction unit is used to extract the first clear liquid from the water washing unit and / or the second clear liquid from the membrane filter using organic solvent from the product separation unit.

[0271] Option 9: The reaction system according to Option 8, wherein the reaction unit includes 1-4 reactors, preferably 1-2 reactors;

[0272] Preferably, the reactor is a stirred tank reactor;

[0273] Preferably, each reactor is independently connected to a hydrogen peroxide feed line;

[0274] Preferably, the catalyst separator includes a vessel body and a stirrer, an inner extension tube, and an inner sleeve disposed within the vessel body; the inner sleeve is fitted inside the inner extension tube and is used to convey a portion of the mixed extract of the reaction slurry and organic solvent to the inner extension tube; the inner extension tube is used to convey a portion of the mixed extract of the reaction slurry and organic solvent to the vessel body for two-phase separation to obtain an organic phase and an aqueous phase; a gas phase balance port is provided on the side wall of the inner extension tube to maintain the gas phase balance of the vessel body; the stirring paddle of the stirrer is disposed in the aqueous phase section of the vessel body to stir the aqueous phase;

[0275] Preferably, the top end of the inner tube is located outside the vessel body, and the bottom end of the inner tube is located inside the vessel body;

[0276] Preferably, the top end of the inner sleeve is flush with the top end of the inner extension tube, and the top of the annular space formed by the inner sleeve and the inner extension tube is closed.

[0277] Preferably, the bottom end of the inner tube is provided with an anti-impact baffle to buffer the mixed extraction material of part of the reaction slurry and organic solvent;

[0278] Preferably, the filtration accuracy of the membrane tube in the membrane filter is 0.01-50 μm, and more preferably 0.05-10 μm;

[0279] Preferably, the membrane tube in the membrane filter is made of at least one of ceramic, metal and high-density polyethylene, preferably ceramic and / or metal, and more preferably metal.

[0280] Option 10: The reaction system according to Option 9, wherein the system further includes an ammonia removal unit connected to the aqueous phase outlet of the extraction unit for separating wastewater and ammonia in the aqueous phase;

[0281] Preferably, the circulating catalyst slurry pipeline is further provided with a circulating ammonia water inlet, and the ammonia water outlet of the deammoniation unit is connected to the circulating ammonia water inlet on the circulating catalyst slurry pipeline for returning ammonia water to the ammonium oxime reaction;

[0282] Preferably, the system further includes a tail gas absorption unit, with the gas phase outlet of the reactor connected to the tail gas absorption unit and the liquid phase outlet of the tail gas absorption unit connected to the reactor, for contacting the gas generated by the reaction with demineralized water to remove ammonia.

[0283] To facilitate understanding of the present invention, the following embodiments are provided. However, these embodiments are only for the purpose of helping to understand the present invention and should not be regarded as specific limitations of the present invention.

[0284] Example

[0285] The present invention will be further described below with reference to the embodiments, but the scope of the present invention is not limited to these embodiments.

[0286] Characterization methods

[0287] Gas chromatography: An Agilent 7890B gas chromatograph equipped with a flame ionization detector (FID) was used for product analysis. The chromatographic column was an Agilent HP-INNOWax capillary column (stationary phase: polyethylene glycol, column length 30 m, inner diameter 0.25 mm, film thickness 0.25 μm). The chromatographic conditions were as follows: injector temperature 260 °C; detector (FID) temperature 280 °C. A temperature program was used: initial column temperature 100 °C, held for 10 minutes; then increased to 230 °C at a rate of 20 °C / min and held for 20 minutes. High-purity nitrogen (N2) was used as the carrier gas at a flow rate of 1.0 mL / min. Split injection was used with a split ratio of 50:1. The injection volume was 1.0 μL. The organic phase effluent from the catalyst separator was cooled to room temperature, and a sample was taken for GC analysis. The mass percentages of carbonyl compounds, oximes, and reaction impurities were calculated using the area normalization method with correction factors. The carbonyl compound conversion, oxime selectivity, and catalyst consumption were then calculated using the following formula:

[0288] Where w% is the mass percentage of the corresponding component in the organic phase from the catalyst separator; α is the molecular weight ratio of the carbonyl compound and the oxime (e.g., the molecular weight ratio of cyclohexanone and cyclohexanone oxime is 0.867); m (catalyst) is the total amount of catalyst added, in g; F (carbonyl compound) is the carbonyl compound feed flow rate, in kg / h; t is the system operating time, in h; when calculating catalyst consumption, the carbonyl compound conversion rate and oxime selectivity are the algebraic averages of the initial and final conversion rates and selectivities.

[0289] The oxime product obtained from the distillation vessel was sampled and prepared into a 25% oxime ethanol solution with anhydrous ethanol. GC analysis was performed, and the purity of the oxime product was calculated using the correction factor area normalization method.

[0290] Unless otherwise specified, the reagents used in the following examples and comparative examples are all conventionally used in the art, and the methods employed are all conventionally used in the art.

[0291] Example I-1

[0292] The system for preparing oximes shown in Figure 1 was used.

[0293] Cyclohexanone, ammonia, and a circulating catalyst slurry were mixed and fed into a reactor. Hydrogen peroxide was introduced into the reactor near the bottom agitator via a feed distributor. The reaction was carried out at 90°C and 0.4 MPaG. The effective volume of the reactor was 3 L, and it contained TS-1 titanium-silicon molecular sieve catalyst. The mass fraction of the catalyst in the circulating catalyst slurry was 2.5%. The feed flow rate of cyclohexanone was 353 g / h, the feed flow rate of ammonia was 67 g / h, and the feed flow rate of hydrogen peroxide (hydrogen peroxide concentration of 35 wt%) was... The flow rate of the circulating catalyst slurry was 402 g / h, and the mass fraction of cyclohexanone oxime in the circulating catalyst slurry was 1.5%. The molar ratio of hydrogen peroxide to carbonyl compounds in the reaction system was 1.15:1. The reaction slurry obtained by the ammonoximation reaction was mixed with toluene for extraction. The resulting mixed extract was cooled to 70°C by a heat exchanger and then sent to the catalyst separator. The toluene flow rate was 810 g / h, and the mass ratio of toluene to cyclohexanone oxime in the reaction product was 2:1.

[0294] The aqueous phase obtained from the two-phase separation in the catalyst separator is sent to a membrane filter (the membrane filter is equipped with a 10mm diameter, 200mm long sintered metal membrane tube with a filtration accuracy of 0.2μm). The catalyst-rich stream flowing out from the center of the membrane tube is recycled back to the reactor. The second clear liquid obtained by permeating into the shell from the inside of the membrane tube is sent to the extraction tower through the clear liquid discharge line. The clear liquid discharge line is equipped with a backwashing line, and the backwashing medium is the second clear liquid. The organic phase obtained from the two-phase separation in the catalyst separator is sent to a water washing tank. The organic phase after water washing in the water washing tank is sent to the toluene oxime separation process. In the toluene oxime separation process, the water-washed organic phase is separated by a distillation column. Cyclohexanone oxime product is obtained from the bottom of the column, and the toluene obtained from the top of the column is sent to the extraction tower.

[0295] The gas phase obtained from the reaction is sent to the tail gas absorption process, where demineralized water is used to countercurrently absorb ammonia from the tail gas in the absorption tower. The amount of demineralized water added is 71 g / h, the operating pressure is atmospheric pressure, and the absorbent is sent to the reaction vessel.

[0296] The first clear liquid (wash water) after washing in the washing tank is mixed with the second clear liquid and sent to the extraction process. In the extraction tower, toluene from the toluene oxime separation process is used to countercurrently extract cyclohexanone oxime from the water (first clear liquid and second clear liquid), where water is the continuous phase and toluene is the dispersed phase. The toluene phase obtained by extraction is mixed with the reaction slurry and then sent to the heat exchanger. The aqueous phase obtained by extraction is sent to the deammoniation tower for deammoniation. The operating pressure is atmospheric pressure. The ammonia water obtained from the top of the tower is recycled back to the reactor, and the wastewater obtained from the reactor is discharged.

[0297] The reactor is equipped with baffles and a stirrer. The stirrer is a propeller-type stirrer with a stirring speed of 600 rpm.

[0298] A catalyst separator, as shown in Figure 3, includes a vessel body and a stirrer, an inner extension tube, and an inner sleeve disposed within the vessel body. The top end of the inner extension tube is located outside the vessel body, and the bottom end of the inner extension tube is located inside the vessel body. The ratio of the length of the inner extension tube extending below the upper tangent of the vessel body to the vertical distance between the tangent and the lower tangent of the vessel body is 0.85:1. The inner sleeve is fitted inside the inner extension tube, and the top end of the inner sleeve is flush with the top end of the inner extension tube. The inner sleeve and the inner extension tube form an annular shape. The space is closed at the top, and the length ratio of the inner tube to the inner sleeve is 15:1; a gas phase balance port is provided on the side wall of the inner tube, which is connected to the gas phase space of the vessel to ensure gas phase balance; the stirring paddle of the stirrer is located in the water phase section of the vessel, and the stirring paddle has one layer; an anti-impact baffle is provided at the bottom of the inner tube, and the vessel is also provided with an overflow weir (L-shaped plate, one end of which is connected to the inner wall of the vessel) and an organic phase outlet connected to the overflow weir; a gas phase outlet is provided at the top of the vessel.

[0299] The operating conditions inside the catalyst separator are: temperature 69℃, pressure 0.4MPaG; the agitator is an anchor agitator with a rotation speed of 180rpm.

[0300] Under the above process conditions, sampling began after 10 hours of operation (the conversion rate and selectivity at this time are the initial conversion rate and selectivity). Afterwards, samples were taken from the organic phase output of the catalyst separator and the cyclohexanone oxime product for analysis every 10 hours. When the cyclohexanone conversion rate decreased to below 99.6%, the feeding of cyclohexanone, ammonia, and hydrogen peroxide was stopped. The conversion rate, selectivity, and cyclohexanone oxime product purity at this point are the final conversion rate, final selectivity, and cyclohexanone oxime product purity. The system running time was recorded, and catalyst consumption was calculated. The conversion rate, selectivity, catalyst consumption, cyclohexanone oxime product purity, and system running time data for Example I-1 are shown in Table 1.

[0301] Example I-2

[0302] The method is the same as described in Example I-1, except that the circulating catalyst slurry feed flow rate is 5750 g / h.

[0303] The conversion rate, selectivity, catalyst consumption, cyclohexanone oxime product purity, and system uptime data for Example I-2 are shown in Table 1.

[0304] Example I-3

[0305] The method described in Example I-1 is different except that the reaction temperature is 95°C.

[0306] The conversion rate, selectivity, catalyst consumption, cyclohexanone oxime product purity, and system uptime data for Examples I-3 are shown in Table 1.

[0307] Example I-4

[0308] The method is the same as described in Example I-1, except that the mass fraction of the catalyst in the circulating catalyst slurry is 2%.

[0309] The conversion rate, selectivity, catalyst consumption, cyclohexanone oxime product purity, and system uptime data for Examples I-4 are shown in Table 1.

[0310] Example I-5

[0311] The method described in Example I-1 differs from that, as shown in Figure 4, the membrane filter is installed in the aqueous phase section below the height of the anti-surge baffle of the catalyst separator. The aqueous phase obtained from the two-phase separation in the catalyst separator enters a membrane filter (the membrane filter is a sintered metal membrane tube with a diameter of 10 mm and a length of 100 mm, with a filtration accuracy of 0.2 μm; one end of the membrane tube is closed, and the other end is connected to a collecting pipe, which is connected to the outlet of the second clear liquid) installed in the aqueous phase section of the catalyst separator. The liquid in the aqueous phase permeates from the outer surface of the membrane tube to the inner surface of the membrane tube to obtain the second clear liquid. The second clear liquid is collected by the collecting pipe and sent to the extraction tower. A backwashing line is installed on the clear liquid outlet line, and the backwashing medium is the second clear liquid. The catalyst-rich stream after filtration by the membrane filter is recycled back to the reactor. The organic phase obtained from the two-phase separation in the catalyst separator is sent to a water washing tank. The organic phase after water washing in the water washing tank is sent to the toluene oxime separation process. In the toluene oxime separation process, the organic phase after water washing is separated by a distillation column. Cyclohexanone oxime product is obtained at the bottom of the column, and the toluene obtained at the top of the column is sent to the extraction tower.

[0312] The conversion rate, selectivity, catalyst consumption, cyclohexanone oxime product purity, and system uptime data for Examples I-5 are shown in Table 1.

[0313] Example I-6

[0314] The method described in Example I-1 is different in that the circulating catalyst slurry feed flow rate is 5600 g / h, the mass fraction of cyclohexanone oxime in the circulating catalyst slurry is 2.5%, the toluene flow rate is 400 g / h, and the mass ratio of toluene to cyclohexanone oxime in the reaction product is 1:1.

[0315] The conversion rate, selectivity, catalyst consumption, cyclohexanone oxime product purity, and system uptime data for Examples I-6 are shown in Table 1.

[0316] Example I-7

[0317] The method is the same as described in Example I-1, except that the circulating catalyst slurry feed flow rate is 9500 g / h.

[0318] The conversion rate, selectivity, catalyst consumption, cyclohexanone oxime product purity, and system uptime data for Examples I-7 are shown in Table 1.

[0319] Comparative Example I-1

[0320] The method described in Example I-1 is different in that cyclohexanone, ammonia and circulating catalyst slurry are mixed with hydrogen peroxide and then fed into the reactor, and the feed flow rate of the circulating catalyst slurry is 2700 g / h.

[0321] The conversion rate, selectivity, catalyst consumption, cyclohexanone oxime product purity, and system uptime data for Comparative Example I-1 are shown in Table 1.

[0322] Table 1

[0323] As can be seen from the results in Table 1, compared with the comparative example, the method for preparing oximes provided in this embodiment of the invention significantly extends the catalyst lifespan, improves the system operation stability, greatly reduces catalyst consumption, and produces oxime products with high purity, while achieving high carbonyl compound conversion and high oxime selectivity.

[0324] Example II-1

[0325] The system for preparing oximes shown in Figure 2 was used.

[0326] Cyclohexanone, ammonia, and circulating catalyst slurry are mixed and fed into a reactor. Hydrogen peroxide is introduced into the reactor near the bottom agitator via a feed distributor. The reaction is carried out at 90℃ and 0.4 MPaG. The effective volume of the reactor is 3L, and it contains TS-1 titanium-silicon molecular sieve catalyst. The mass fraction of the catalyst in the circulating catalyst slurry is 3%. The feed flow rates are 420 g / h for cyclohexanone, 80 g / h for ammonia, and 490 g / h for hydrogen peroxide (35% hydrogen peroxide content). The feed flow rate is 7500 g / h, of which the mass fraction of cyclohexanone oxime in the circulating catalyst slurry is 1.5%, and the molar ratio of hydrogen peroxide to carbonyl compounds in the reaction system is 1.18:1. Part of the reaction slurry obtained by the ammoniation reaction is sent to the heat exchanger at a flow rate of 30000 g / h, and the remaining reaction slurry is mixed with toluene at a flow rate of 8490 g / h and the resulting mixed extract is sent to the catalyst separator. The toluene flow rate is 1000 g / h, and the mass ratio of toluene to cyclohexanone oxime in the remaining reaction slurry is 2:1.

[0327] The aqueous phase obtained from the two-phase separation in the catalyst separator is sent to a membrane filter (the membrane filter is equipped with a single sintered metal membrane tube with a filtration accuracy of 0.2 μm). The catalyst-rich stream flowing out from the center of the membrane tube is recycled back to the reactor. The second clear liquid obtained by permeating into the shell from the inside of the membrane tube is sent to the extraction tower via the clear liquid discharge line. The clear liquid discharge line is equipped with a backwashing line, and the backwashing medium is the second clear liquid. The organic phase obtained from the two-phase separation in the catalyst separator is sent to a water washing tank. The organic phase after water washing in the water washing tank is sent to the toluene oxime separation process. In the toluene oxime separation process, the water-washed organic phase is separated by a distillation column. Cyclohexanone oxime product is obtained from the bottom of the column, and the toluene obtained from the top of the column is sent to the extraction tower.

[0328] The gas phase obtained from the reaction is sent to the tail gas absorption process, where ammonia in the tail gas is absorbed countercurrently with demineralized water in the absorption tower. The amount of demineralized water added is 90 g / h, the operating pressure is atmospheric pressure, and the absorbent is sent to the reaction vessel.

[0329] The first clear liquid (wash water) after washing in the washing tank is mixed with the second clear liquid and sent to the extraction process. In the extraction tower, toluene from the toluene oxime separation process is used to countercurrently extract cyclohexanone oxime from the water (first clear liquid and second clear liquid), wherein water is the continuous phase and toluene is the dispersed phase. The toluene phase obtained by extraction is mixed with the remaining part of the reaction slurry and then sent to the catalyst separator for two-phase separation. The aqueous phase obtained by extraction is sent to the deammoniation tower for deammoniation. The operating pressure is atmospheric pressure. The ammonia water obtained from the top of the tower is recycled back to the reactor, and the wastewater obtained from the bottom of the tower is discharged.

[0330] The reactor is equipped with baffles and a stirrer. The stirrer is a propeller-type stirrer with a stirring speed of 600 rpm.

[0331] The catalyst separator is the same as the catalyst separator in Example I-1.

[0332] The operating conditions inside the catalyst separator are: temperature 88℃, pressure 0.4MPaG; the agitator is an anchor agitator with a rotation speed of 180rpm.

[0333] Under the above process conditions, sampling began after 10 hours of operation (the conversion rate and selectivity at this time are the initial conversion rate and selectivity). Afterwards, samples were taken every 10 hours to analyze the organic phase output from the catalyst separator and the cyclohexanone oxime product. When the cyclohexanone conversion rate decreased to below 99.6%, the feeding of cyclohexanone, ammonia, and hydrogen peroxide was stopped. The conversion rate, selectivity, and cyclohexanone oxime product purity at this point are the final conversion rate, final selectivity, and cyclohexanone oxime product purity. The system operating time was recorded, and catalyst consumption was calculated. The conversion rate, selectivity, catalyst consumption, cyclohexanone oxime product purity, and system operating time data for Example II-1 are shown in Table 2.

[0334] Example II-2

[0335] The method is described in accordance with Example II-1, except that the flow rate of the circulating catalyst slurry is changed from 7500 g / h to 6800 g / h; and the flow rate of the remaining reaction slurry is changed from 8490 g / h to 7790 g / h.

[0336] The conversion rate, selectivity, catalyst consumption, cyclohexanone oxime product purity, and system uptime data for Example II-2 are shown in Table 2.

[0337] Example II-3

[0338] The method is the same as described in Example II-1, except that the reaction temperature is 95°C.

[0339] The conversion rate, selectivity, catalyst consumption, cyclohexanone oxime product purity, and system uptime data for Example II-3 are shown in Table 2.

[0340] Example II-4

[0341] The method is the same as described in Example II-1, except that the mass fraction of the catalyst in the circulating catalyst slurry is 2%.

[0342] The conversion rate, selectivity, catalyst consumption, cyclohexanone oxime product purity, and system uptime data for Example II-4 are shown in Table 2.

[0343] Example II-5

[0344] The method is described in accordance with Example II-1, except that the circulating catalyst slurry feed flow rate is 6600 g / h, wherein the mass fraction of cyclohexanone oxime in the circulating catalyst slurry is 2.5%; the flow rate of the remaining reaction slurry is replaced by 6790 g / h instead of 8490 g / h, the toluene flow rate is 500 g / h, and the mass ratio of toluene to cyclohexanone oxime in the remaining reaction slurry is 1:1; as shown in Figure 4, the membrane filter is installed in the aqueous phase section below the height of the anti-surge baffle of the catalyst separator. The aqueous phase obtained from the two-phase separation in the catalyst separator enters a membrane filter (the membrane filter is a sintered metal membrane tube with a diameter of 10 mm and a length of 100 mm, with a filtration accuracy of 0.2 μm; one end of the membrane tube is closed, and the other end is connected to a collecting pipe, which is connected to the outlet of the second clear liquid) installed in the aqueous phase section of the catalyst separator. The liquid in the aqueous phase permeates from the outer surface of the membrane tube to the inner surface of the membrane tube to obtain the second clear liquid. The second clear liquid is collected by the collecting pipe and sent to the extraction tower. A backwashing line is installed on the clear liquid outlet line, and the backwashing medium is the second clear liquid. The catalyst-rich stream after filtration by the membrane filter is recycled back to the reactor. The organic phase obtained from the two-phase separation in the catalyst separator is sent to a water washing tank. The organic phase after water washing in the water washing tank is sent to the toluene oxime separation process. In the toluene oxime separation process, the organic phase after water washing is separated by a distillation column. Cyclohexanone oxime product is obtained at the bottom of the column, and the toluene obtained at the top of the column is sent to the extraction tower.

[0345] The conversion rate, selectivity, catalyst consumption, cyclohexanone oxime product purity, and system uptime data for Examples II-5 are shown in Table 2.

[0346] Example II-6

[0347] The method is the same as described in Example II-1, except that the circulating catalyst slurry feed flow rate is 12000 g / h.

[0348] The conversion rate, selectivity, catalyst consumption, cyclohexanone oxime product purity, and system uptime data for Examples II-6 are shown in Table 2.

[0349] Comparative Example II-1

[0350] The method is the same as described in Example II-1, except that cyclohexanone, ammonia, and circulating catalyst slurry are mixed with hydrogen peroxide and then fed into the reactor, with the circulating catalyst slurry volume being 3000 g / h.

[0351] The conversion rate, selectivity, catalyst consumption, cyclohexanone oxime product purity, and system uptime data for Comparative Example II-1 are shown in Table 2.

[0352] Table 2

[0353] As can be seen from the results in Table 2, compared with the comparative example, the method for preparing oximes provided in this embodiment of the invention significantly extends the catalyst lifespan, improves the system operation stability, greatly reduces catalyst consumption, and produces oxime products with high purity, while achieving high carbonyl compound conversion and high oxime selectivity.

[0354] The specific embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combining the various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A method for preparing oximes, characterized in that, The method includes the following steps: (1) A mixture stream is obtained by mixing carbonyl compound, ammonia and circulating catalyst slurry, wherein the feed ratio of carbonyl compound to circulating catalyst slurry by mass is 1:10-50, preferably 1:15-30, and then the mixture stream is contacted with hydrogen peroxide to carry out an ammonium oxime reaction to obtain a reaction slurry. (2) The reaction slurry is mixed with an organic solvent and then the two phases are separated to obtain an oxime-containing organic phase and a catalyst-containing aqueous phase; (3) Optionally, the organic phase obtained in step (2) is washed with water and then separated to obtain an organic solvent and an oxime product; (4) The aqueous phase obtained in step (2) is filtered and returned to step (1) to provide at least a portion of the circulating catalyst slurry. Preferably, no additional organic solvent is introduced in the ammonium oxime reaction described in step (1).

2. The method according to claim 1, wherein, Step (2) further includes: The reaction slurry is deheated before being mixed with the organic solvent; or, The mixture of reaction slurry and organic solvent is heated, followed by two-phase separation; or A portion of the reaction slurry is mixed with an organic solvent, and then the two phases are separated to obtain an oxime-containing organic phase and a catalyst-containing aqueous phase. The remaining portion of the reaction slurry is returned to the ammonia oxime reaction in step (1) after being heated. Preferably, the mass ratio of the portion of the reaction slurry to the remaining portion of the reaction slurry is 1:2-8, and more preferably 1:3-5. Preferably, in step (2), after heat treatment, the temperature of the reaction slurry, the mixture of the reaction slurry and the organic solvent, or the remaining part of the reaction slurry is 40-85°C.

3. The method according to claim 1 or 2, wherein, In step (1), the molar ratio of hydrogen peroxide to carbonyl compound is 1-1.5:1, preferably 1-1.3:1; Preferably, the molar ratio of ammonia to carbonyl compound is 1-1.5:1, more preferably 1-1.3:1; Preferably, the mass fraction of oxime in the circulating catalyst slurry is 0.1-4%, more preferably 0.5-3%; Preferably, the mass fraction of the catalyst in the circulating catalyst slurry is 0.1%-15%, more preferably 1%-10%; Preferably, the hydrogen peroxide is provided by hydrogen peroxide solution, wherein the mass concentration of hydrogen peroxide in the hydrogen peroxide solution is 15-80 wt%, preferably 20-70 wt%.

4. The method according to any one of claims 1-3, wherein the catalyst comprises a titanium-silicon molecular sieve, the titanium-silicon molecular sieve being selected from at least one of TS-1, TS-2, Ti-ZSM-5, Ti-ZSM-12, Ti-ZSM-48, Ti-β, Ti-MCM-41, Ti-MOR, Ti-MWW and Ti-SBA-15; Preferably, the carbonyl compound is selected from C3-C4. 10 Aliphatic ketones, C5-C 10 Alicyclic ketones, C6-C 10 Aromatic ketones, C5-C 10 Alicyclic aldehydes, C6-C 10 At least one of aromatic aldehydes, preferably at least one of cyclohexanone, acetone, methyl ethyl ketone, cyclopentanone, acetophenone, p-hydroxyacetophenone, furfural, benzaldehyde and p-methylbenzaldehyde, more preferably at least one of acetone, methyl ethyl ketone, cyclopentanone and cyclohexanone; Preferably, the organic solvent is selected from C6-C. 12 Alkanes, C5-C 11 Cycloalkanes, C6-C 10 At least one of the aromatic hydrocarbons, preferably selected from C6-C 10 Aromatics and C6-C 10 At least one of the cycloalkanes, more preferably toluene and / or cyclohexane; Preferably, the mass ratio of the organic solvent to the oxime in the reaction slurry is 0.5-5:1, more preferably 1-3:

1.

5. The method according to any one of claims 1-4, wherein, The conditions for the ammonium oxime reaction include: a reaction temperature of 60-100℃, preferably 80-95℃; and a reaction pressure of 0-1 MPaG, preferably 0.1-0.5 MPaG. Preferably, the ammonium oxime reaction is carried out in a stirred tank reactor; Preferably, step (1) further includes: contacting the gas generated by the ammonium oximation reaction with demineralized water to remove ammonia, and returning the resulting absorbent to the ammonium oximation reaction; Preferably, the water washing in step (3) includes washing the organic phase obtained in step (2) with water to separate the oxime-rich organic phase and the first supernatant; Preferably, the water washing stage in step (3) is 1-5 stages, and more preferably 1-3 stages.

6. The method according to any one of claims 1-5, wherein, The two-phase separation described in step (2) is carried out in a catalyst separator. Preferably, the catalyst separator includes a vessel body and a stirrer, an inner extension tube, and an inner sleeve disposed within the vessel body; Preferably, the two-phase separation in step (2) is carried out by the following process: the mixed extract stream containing the reaction slurry and organic solvent is transported to the inner tube through the inner sleeve installed inside the inner tube, and then transported to the vessel body through the inner tube for two-phase separation to obtain the organic phase and the aqueous phase; Preferably, the two-phase separation in step (2) is carried out while the aqueous phase is stirred; Preferably, the conditions for the two-phase separation in step (2) include: pressure of 0-500 kPaG and temperature of 40-90℃.

7. The method according to any one of claims 1-6, wherein, Step (4) includes membrane filtration of the aqueous phase obtained in step (2) to obtain a catalyst-rich stream and a second clear liquid; the obtained catalyst-rich stream is returned to step (1) to provide at least a portion of the circulating catalyst slurry; Preferably, the circulating catalyst slurry comprises the catalyst-rich stream obtained in step (4) and optionally a slurry containing fresh catalyst; Preferably, the membrane filtration is carried out in a membrane filter, which is located in the aqueous phase section of the catalyst separator or connected to the aqueous phase outlet of the catalyst separator; Preferably, the filtration accuracy of the membrane filter is 0.01-50 μm, and more preferably 0.05-10 μm; Preferably, the method further includes: removing heat from the catalyst-rich stream obtained in step (4); Preferably, the method further includes (5) extracting the first clear liquid and / or the second clear liquid with the organic solvent obtained in step (3) to separate the aqueous phase and the organic phase, and returning the extracted organic phase to step (2) to provide at least a portion of the organic solvent; Preferably, the extraction method in step (5) is countercurrent extraction; Preferably, the extraction temperature is 30-90℃, and more preferably 40-80℃; Preferably, the extraction in step (5) further includes: removing ammonia from the aqueous phase obtained by the extraction to obtain ammonia water and wastewater; and returning the obtained ammonia water to the ammonia oxime reaction in step (1).

8. The method according to any one of claims 1-7, wherein, The carbonyl compound is cyclohexanone, and in step (1), the mass fraction of the carbonyl compound is 2-8%, preferably 3-6%, based on the total amount of the carbonyl compound and the circulating catalyst slurry.

9. A system for preparing oximes, characterized in that, The system includes a reaction unit, an optional water washing unit, an optional extraction unit, and an optional product separation unit. The reaction unit includes at least one reactor, a catalyst separator, and a filter. The reactor is connected to a circulating catalyst slurry pipeline and a hydrogen peroxide feed pipeline, respectively. The circulating catalyst slurry pipeline is provided with a carbonyl compound inlet and an ammonia inlet. The reactor is used to contact a mixture stream containing carbonyl compound, ammonia and circulating catalyst slurry from the circulating catalyst slurry pipeline with hydrogen peroxide from the hydrogen peroxide feed pipeline to carry out an ammonium oxime reaction. The circulating catalyst slurry pipeline is configured such that the feed ratio of carbonyl compound to circulating catalyst slurry by mass is 1:10-50, preferably 1:15-30. The reactor and the catalyst separator are connected by a pipeline, which is provided with an organic solvent inlet; the catalyst separator is provided with an aqueous phase outlet and an organic phase outlet, for separating the mixed extract stream containing the reaction slurry from the reactor and the organic solvent into two phases. The organic phase outlet of the catalyst separator is connected to the optional product separation unit via the optional water washing unit, and the aqueous phase outlet of the catalyst separator is connected to the reactor via the filter and the circulating catalyst slurry pipeline; The product separation unit is used to separate the organic phase from the catalyst separator to obtain organic solvents and oxime products.

10. The system according to claim 9, wherein the reaction unit includes a heat extractor; Preferably, the heat exchanger is disposed on the pipeline between the reactor and the catalyst separator, for heat extraction of the reaction slurry before or after mixing with the organic solvent; or, The reactor's reaction slurry outlet is connected to the catalyst separator and the heat exchanger, respectively, for sending part of the reaction slurry into the catalyst separator and returning the remaining part of the reaction slurry to the reactor after heat extraction by the heat exchanger.

11. The system according to claim 9 or 10, wherein, The system includes a water washing unit and an extraction unit, wherein the water washing unit is provided with an aqueous phase outlet and an oxime-rich organic phase outlet; Preferably, the organic phase outlet of the catalyst separator is connected to the water washing unit, the aqueous phase outlet of the water washing unit is connected to the aqueous phase inlet of the extraction unit, the oxime-rich organic phase outlet of the water washing unit is connected to the inlet of the product separation unit, and the water washing unit is used to wash the organic phase from the catalyst separator. Preferably, the organic solvent outlet of the product separation unit is connected to the organic solvent inlet of the extraction unit, and the product separation unit is used to separate the oxime-rich organic phase from the water washing unit; Preferably, the filter is a membrane filter disposed in the aqueous phase section of the catalyst separator or connected to the aqueous phase outlet of the catalyst separator. The membrane filter has a catalyst-rich stream outlet and a clear liquid outlet. The catalyst-rich stream outlet is connected to the reactor through the circulating catalyst slurry pipeline, and the second clear liquid outlet is connected to the aqueous phase inlet of the extraction unit. The membrane filter is used to filter the aqueous phase from the catalyst separator to obtain a catalyst-rich stream and a second clear liquid. The catalyst-rich stream is sent into the reactor, and the second clear liquid is sent into the extraction unit. Preferably, the extraction unit includes at least one extraction tower, and the organic solvent outlet of the extraction unit is connected to the organic solvent inlet of the pipeline between the reactor and the catalyst separator via an organic solvent pipeline, specifically, to the pipeline between the reactor and the heat exchanger or to the pipeline between the heat exchanger and the catalyst separator. The extraction unit is used to extract the first clear liquid from the water washing unit and / or the second clear liquid from the membrane filter using the organic solvent from the product separation unit.

12. The system according to any one of claims 9-11, wherein, The reaction unit includes 1-4 reactors, preferably 1-2 reactors; Preferably, the reactor is a stirred tank reactor; Preferably, each reactor is independently connected to a hydrogen peroxide feed line.

13. The system according to any one of claims 9-12, wherein, The catalyst separator includes a vessel body and a stirrer, an inner extension tube, and an inner sleeve disposed within the vessel body. The inner sleeve is fitted inside the inner extension tube and is used to transport a mixed extract stream containing the reaction slurry and organic solvent to the inner extension tube. The inner extension tube is used to transport the mixed extract stream containing the reaction slurry and organic solvent to the vessel body for two-phase separation to obtain an organic phase and an aqueous phase. A gas phase balance port is provided on the side wall of the inner extension tube to maintain the gas phase balance of the vessel body. The stirring paddle of the stirrer is disposed in the aqueous phase section of the vessel body to stir the aqueous phase. Preferably, the top end of the inner tube is located outside the vessel body, and the bottom end of the inner tube is located inside the vessel body; Preferably, the top end of the inner sleeve is flush with the top end of the inner extension tube, and the top of the annular space formed by the inner sleeve and the inner extension tube is closed. Preferably, the bottom end of the inner tube is provided with an anti-impact baffle to buffer the flow of the reaction slurry and organic solvent after mixing and extraction.

14. The system according to any one of claims 9-13, wherein, The filtration accuracy of the membrane tube in the membrane filter is 0.01-50μm, preferably 0.05-10μm; Preferably, the membrane tube in the membrane filter is made of at least one of ceramic, metal and high-density polyethylene, preferably ceramic and / or metal, and more preferably metal.

15. The system according to any one of claims 9-14, wherein, A heat exchanger is installed on the circulating catalyst slurry pipeline between the membrane filter and the reactor. Preferably, the system further includes an ammonia removal unit connected to the aqueous phase outlet of the extraction unit, used to remove ammonia from the aqueous phase from the extraction unit to obtain ammonia water and wastewater; Preferably, the circulating catalyst slurry pipeline is further provided with a circulating ammonia water inlet, and the ammonia water outlet of the deammoniation unit is connected to the circulating ammonia water inlet of the circulating catalyst slurry pipeline for returning ammonia water to the reactor; Preferably, the system further includes a tail gas absorption unit, the gas phase outlet of the reactor is connected to the tail gas absorption unit, and the liquid phase outlet of the tail gas absorption unit is connected to the reactor, for contacting the gas generated by the reaction with demineralized water to remove ammonia, and the resulting absorbent is returned to the reactor.

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