Process and system for the preparation of cyclohexanone oxime

Abstract

This invention relates to the field of cyclohexanone oxime production, and discloses a method and system for preparing cyclohexanone oxime, comprising: (1) mixing cyclohexanone, ammonia, and a circulating catalyst slurry, and then reacting them with hydrogen peroxide to obtain a reaction slurry containing cyclohexanone oxime, ammonia, water, and a catalyst; wherein the feed cyclohexanone accounts for 2-6% of the total mass of cyclohexanone and the circulating catalyst slurry; (2) mixing the reaction slurry with an organic solvent to obtain a mixed slurry; separating the mixed slurry into two phases to obtain an organic phase containing cyclohexanone oxime and an organic solvent, and an aqueous phase containing a catalyst; wherein the mass ratio of the organic solvent to the cyclohexanone oxime in the reaction slurry is 0.5-5:1; (3) filtering the aqueous phase containing the catalyst through a membrane to obtain a clear liquid and a catalyst-rich stream; returning the catalyst-rich stream to the circulating catalyst slurry provided in step (1). This method can improve the selectivity of cyclohexanone oxime while effectively extending the service life of the catalyst.

Description

Technical Field

[0001] This invention relates to the field of cyclohexanone oxime production, and more specifically to a method and system for preparing cyclohexanone oxime. Background Technology

[0002] Currently, the industrial production of cyclohexanone oxime widely employs the cyclohexanone amination oximation process. This process uses a titanium-containing catalyst and tert-butanol as a solvent. Cyclohexanone undergoes an amination oximation reaction with ammonia and hydrogen peroxide, allowing for the highly selective, one-step direct preparation of cyclohexanone oxime. It boasts advantages such as simple process, low investment, minimal waste emissions, and environmental friendliness. Industrially produced cyclohexanone oxime is typically used as a key intermediate in the preparation of caprolactam.

[0003] In recent years, research on the cyclohexanone aminooxime process without using tert-butanol solvent has been increasing.

[0004] CN105837468A discloses a method for preparing cyclohexanone oxime. The method uses an aqueous solution containing a small amount of inert organic solvent as the solvent, and cyclohexanone, ammonia, and hydrogen peroxide undergo an ammonoximation reaction in the solvent in the presence of an oximation catalyst.

[0005] CN117343010A discloses a method for preparing caprolactam by heterogeneous ammonoximation and gas-phase rearrangement. The method uses cyclohexanone, hydrogen peroxide, and ammonia as raw materials to perform a heterogeneous ammonoximation reaction to generate cyclohexanone oxime. The product of the oximation reaction is mixed with an inert solvent, allowed to stand and separate into layers to obtain the organic phase product, which is then deaminated to obtain a cyclohexanone oxime-inert solvent solution.

[0006] However, all of the above processes suffer from the problem of short catalyst lifespan. How to improve the catalyst lifespan under existing catalyst systems has become a problem that must be considered in the development of cyclohexanone ammonium oxime process. Summary of the Invention

[0007] The purpose of this invention is to overcome the problems existing in the prior art and provide a method and system for preparing cyclohexanone oxime. This method can improve the selectivity of cyclohexanone oxime and effectively extend the service life of the catalyst.

[0008] To achieve the above objectives, the first aspect of the present invention provides a method for preparing cyclohexanone oxime, the method comprising the following steps:

[0009] (1) Cyclohexanone, ammonia and circulating catalyst slurry are mixed and then reacted with hydrogen peroxide to obtain a reaction slurry containing cyclohexanone oxime, ammonia, water and catalyst; wherein, the feed cyclohexanone accounts for 2-6% of the total mass of cyclohexanone and circulating catalyst slurry.

[0010] (2) The reaction slurry and the organic solvent are mixed to obtain a mixed slurry; the mixed slurry is subjected to two-phase separation to obtain an organic phase containing cyclohexanone oxime and organic solvent and an aqueous phase containing catalyst; wherein the mass ratio of organic solvent to cyclohexanone oxime in the reaction slurry is 0.5-5:1;

[0011] (3) The aqueous phase containing the catalyst is subjected to membrane filtration to obtain a clear liquid and a catalyst-rich stream; the catalyst-rich stream is returned to the circulating catalyst slurry provided in step (1);

[0012] Wherein, the reaction slurry is heated and then mixed with an organic solvent; and / or

[0013] The mixed slurry is heated and then subjected to two-phase separation; and / or,

[0014] The aqueous phase containing the catalyst is heated and then subjected to membrane filtration; and / or,

[0015] The catalyst-rich stream is heated and then returned to step (1) for reuse.

[0016] A second aspect of the present invention provides a system for the preparation method of cyclohexanone oxime described in the first aspect, the system comprising a reactor, a heat exchanger, a catalyst separator and a membrane filter connected in sequence;

[0017] The aqueous phase outlet of the catalyst separator is connected to the inlet of the membrane filter;

[0018] The catalyst outlet of the membrane filter is connected to the circulating catalyst inlet of the reactor.

[0019] A third aspect of the present invention provides a system for the method for preparing cyclohexanone oxime according to the first aspect, the system comprising a reactor, a heat exchanger and a catalyst separator connected in sequence;

[0020] A membrane filter is installed in the aqueous phase section of the catalyst separator, and the aqueous phase outlet of the catalyst separator is connected to the circulating catalyst inlet of the reactor.

[0021] During the research process, the inventors of this invention discovered that the following measures can significantly improve the service life of the catalyst while ensuring the selectivity of cyclohexanone oxime: (1) Cyclohexanone, ammonia and circulating catalyst slurry are mixed first, and then contacted with hydrogen peroxide, so that cyclohexanone is in a homogeneous state in the circulating catalyst slurry before contact between cyclohexanone and hydrogen peroxide in the reactor of the ammonium oxime reaction; (2) The concentration of cyclohexanone in cyclohexanone and circulating catalyst slurry is controlled; (3) The mass ratio of organic solvent to cyclohexanone oxime in the reaction slurry is controlled (preferably the content of cyclohexanone oxime in the circulating catalyst slurry is controlled); The above measures can significantly extend the service life of the catalyst and effectively reduce the consumption of the catalyst; Then, the ammonium oxime reaction slurry is further mixed with organic solvent and then subjected to two-phase separation. The catalyst and reaction products are separated by natural phase separation, and the aqueous phase is separated by membrane separation to achieve clear liquid separation and catalyst slurry concentration. The separated catalyst slurry is recycled. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of a system provided in a preferred embodiment of the present invention;

[0023] Figure 2 This is a schematic diagram of a system provided by another preferred embodiment of the present invention.

[0024] Explanation of reference numerals in the attached figures

[0025] exist Figure 1-2 middle,

[0026] 1. Cyclohexanone; 2. Ammonia; 3. Hydrogen peroxide;

[0027] 4. Reactor; 5. Reaction slurry; 6. Organic solvent;

[0028] 7. Heat exchanger; 8. Catalyst separator; 9. Organic phase;

[0029] 10. Aqueous phase; 11. Membrane filter; 12. Catalyst-rich stream;

[0030] 13. Clear liquid. Detailed Implementation

[0031] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0032] The first aspect of this invention provides a method for preparing cyclohexanone oxime, the method comprising the following steps:

[0033] (1) Cyclohexanone, ammonia and circulating catalyst slurry are mixed and then reacted with hydrogen peroxide to obtain a reaction slurry containing cyclohexanone oxime, ammonia, water and catalyst; wherein, the feed cyclohexanone accounts for 2-6% of the total mass of cyclohexanone and circulating catalyst slurry.

[0034] (2) The reaction slurry and the organic solvent are mixed to obtain a mixed slurry; the mixed slurry is subjected to two-phase separation to obtain an organic phase containing cyclohexanone oxime and organic solvent and an aqueous phase containing catalyst; wherein the mass ratio of organic solvent to cyclohexanone oxime in the reaction slurry is 0.5-5:1;

[0035] (3) The aqueous phase containing the catalyst is subjected to membrane filtration to obtain a clear liquid and a catalyst-rich stream; the catalyst-rich stream is returned to the circulating catalyst slurry provided in step (1);

[0036] Wherein, the reaction slurry is heated and then mixed with an organic solvent; and / or

[0037] The mixed slurry is heated and then subjected to two-phase separation; and / or,

[0038] The aqueous phase containing the catalyst is heated and then subjected to membrane filtration; and / or,

[0039] The catalyst-rich stream is heated and then returned to step (1) for reuse.

[0040] According to the present invention, the feed cyclohexanone accounts for 2-6% of the total mass of cyclohexanone and the circulating catalyst slurry, specifically 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 5.5%, 6%, and any two of these values, preferably 3-5.5%.

[0041] According to the present invention, preferably, the mass fraction of cyclohexanone oxime in the circulating catalyst slurry is 0.1-4%, specifically 0.1%, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, and any two of these values, preferably 0.5-3%. This preferred embodiment improves the solubility of cyclohexanone in the circulating catalyst slurry, thereby extending the catalyst's lifespan.

[0042] The present invention does not impose any particular limitation on the specific conditions of the reaction described in step (1), and can refer to conventional methods in the art.

[0043] According to the present invention, preferably, the reaction temperature of the reaction in step (1) is 70-100℃, more preferably 80-95℃; and the reaction pressure is 0-0.5MPaG, more preferably 0.2-0.4MPaG.

[0044] According to the present invention, preferably, the molar ratio of hydrogen peroxide to cyclohexanone is 1-1.5:1.

[0045] Preferably, the hydrogen peroxide exists in the form of a hydrogen peroxide solution. The hydrogen peroxide solution described in this invention is commercially available and will not be described in detail here.

[0046] According to the present invention, preferably, the molar ratio of ammonia to cyclohexanone is 1-1.5:1.

[0047] According to the present invention, preferably, the mass fraction of the catalyst in the circulating catalyst slurry is 0.1-15%, more preferably 1-10%.

[0048] This invention does not specifically limit the type of catalyst, and various catalysts conventionally used in the art can be employed. 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 molecular sieves.

[0049] In this invention, there is no particular limitation on the form of the catalyst. 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.

[0050] According to the present invention, preferably, no organic solvent is added in the reaction described in step (1). The solvent may be any organic solvent commonly used in the art, such as tert-butanol.

[0051] Preferably, the reaction in step (1) is carried out under stirring conditions.

[0052] The present invention does not impose any particular limitation on the stirring, and appropriate selection can be made according to the actual situation.

[0053] According to the present invention, in step (2), the mass ratio of organic solvent to cyclohexanone oxime is 0.5-5:1, specifically 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, and any two of these point values ​​forming a range.

[0054] According to the present invention, preferably, the organic solvent is 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 at least one of aromatics having 6-10 carbon atoms and cycloalkanes having 6-10 carbon atoms, and more preferably toluene and / or cyclohexane.

[0055] In step (2) of this invention, cyclohexanone oxime is extracted into the organic phase, and the catalyst is dispersed in the aqueous phase, effectively separating the catalyst from the reaction product. The separated catalyst is recycled, and the organic phase is sent to the downstream product tank.

[0056] According to the present invention, preferably, the operating conditions for the two-phase separation in step (2) include: a temperature of 40-90°C and a pressure of 0-0.5 MPaG.

[0057] According to the present invention, preferably, the two-phase separation in step (2) is carried out in a catalyst separator. The present invention does not particularly limit the specific type of catalyst separator; any separator capable of achieving catalyst separation can be used.

[0058] Preferably, the catalyst separator includes a vessel body and a stirrer, an inner extension tube, and an inner sleeve disposed within the vessel body;

[0059] The inner sleeve is fitted inside the inner extension tube, and the inner sleeve is used to transport the mixed slurry of reaction slurry and organic solvent to the inner extension tube;

[0060] The inner tube is used to transport the mixture of reaction slurry and organic solvent to the reactor body for two-phase separation to obtain an organic phase and an aqueous phase;

[0061] 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;

[0062] The agitator's stirring paddle is positioned within the aqueous phase section of the vessel and is used to agitate the aqueous phase.

[0063] In the catalyst separator of the present invention, the combination of the inner extension tube and the inner sleeve can reduce the amount of catalyst carried in the organic phase; the stirrer can prevent the catalyst from depositing at the bottom of the vessel, while ensuring the separation of the organic phase and the aqueous phase, avoiding back mixing of the organic phase and the aqueous phase, and ensuring the continuous and stable separation of the two phases and the circulation of the catalyst.

[0064] The present invention does not impose any particular limitation on the type of stirrer; any conventional choice in the art is acceptable.

[0065] According to the present invention, preferably, a gas phase balance port is provided on the side wall of the inner tube to maintain the gas phase balance of the vessel body.

[0066] In this invention, preferably, the gas phase balance port is directly connected to the gas phase space at the top of the vessel body, or the gas phase balance port is connected to the gas phase space at the top of the vessel body through an external pipeline.

[0067] Preferably, the top end of the inner sleeve is flush with the top end of the inner extension tube.

[0068] According to the present invention, preferably, the top of the annular space formed by the inner sleeve and the inner extension tube is closed.

[0069] According to the present invention, preferably, the ratio of the length of the inner sleeve to the length of the inner extension tube is 5-30:1, more preferably 8-25:1. By optimizing the lengths of the inner extension tube and the inner sleeve, catalyst entrainment loss can be reduced. When the ratio of their lengths is not within the preferred range, it will lead to an increase in catalyst entrainment loss.

[0070] According to the present invention, preferably, the ratio of the length of the inner tube extending below the upper tangent of the reactor body to the vertical distance between the upper and lower tangents of the reactor body is 0.3-0.95:1, more preferably 0.4-0.9:1. By optimizing the position of the inner tube in the reactor body, the entrainment of the catalyst into the organic phase can be effectively suppressed; when the ratio is not within the above-mentioned preferred range, it will lead to the defect of increased catalyst entrainment in the organic phase.

[0071] 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 cylindrical wall; the lower tangent of the vessel body refers to the tangential section at the junction of the lower end cap and the cylindrical wall.

[0072] In this invention, the length of the inner tube above the tangent on the vessel body is not particularly limited, as long as the aforementioned length of the inner tube extending below the tangent on the vessel body is met.

[0073] According to the present invention, preferably, an anti-impact baffle is provided at the bottom end of the inner tube, the anti-impact baffle being used to buffer the mixture of reaction slurry and organic solvent. By providing the anti-impact baffle, the mixture of ammonium oxime reaction slurry and organic solvent is effectively buffered, preventing liquid impact from causing fluctuations at the interface between the organic and aqueous phases.

[0074] Preferably, the vessel body is provided with an overflow weir for overflowing the organic phase. The present invention does not particularly limit the overflow weir; any conventional choice in the art is acceptable.

[0075] Preferably, the upper part of the vessel body is provided with an organic phase outlet, which is connected to the overflow weir.

[0076] In this invention, preferably, the bottom of the vessel is provided with a water phase outlet.

[0077] In this invention, preferably, a gas phase outlet is provided at the top of the vessel.

[0078] In this invention, the clear liquid separated by membrane filtration in step (3) is mainly sent to the downstream wastewater tank.

[0079] According to the present invention, preferably, the membrane used in step (3) for membrane filtration is selected from at least one of ceramic membrane, metal membrane and polyethylene membrane, and more preferably a metal membrane.

[0080] The present invention allows for a wide range of filtration accuracy requirements for the membrane, and even membranes with lower accuracy can meet the filtration requirements, which helps to reduce processing costs. Preferably, the membrane used for membrane filtration in step (3) has a filtration accuracy of 0.01-50 micrometers.

[0081] According to the present invention, preferably, the heat extraction results in the temperature of the catalyst-rich stream returned to step (1) being 40-90°C. In this invention, this recovered heat can be reused to improve energy efficiency.

[0082] According to the present invention, preferably, the circulating catalyst slurry comprises the catalyst-rich stream obtained in step (3) and optionally a slurry containing fresh catalyst.

[0083] In this invention, a slurry containing fresh catalyst can be added intermittently according to specific working conditions. The slurry containing fresh catalyst is a slurry containing fresh catalyst prepared with water.

[0084] A second aspect of the present invention provides a system for the preparation method of cyclohexanone oxime described in the first aspect, the system comprising a reactor, a heat exchanger, a catalyst separator and a membrane filter connected in sequence;

[0085] The aqueous phase outlet of the catalyst separator is connected to the inlet of the membrane filter;

[0086] The catalyst outlet of the membrane filter is connected to the circulating catalyst inlet of the reactor.

[0087] A third aspect of the present invention provides a system for the method for preparing cyclohexanone oxime according to the first aspect, the system comprising a reactor, a heat exchanger and a catalyst separator connected in sequence;

[0088] A membrane filter is installed in the aqueous phase section of the catalyst separator, and the aqueous phase outlet of the catalyst separator is connected to the circulating catalyst inlet of the reactor.

[0089] The present invention allows for a wide range of reactor types, including various reactors conventionally used in the field that can achieve the above-mentioned reaction functions.

[0090] Preferably, the reactor is equipped with a stirrer. The stirrer can be a conventional choice in the art. Preferably, the stirrer is a propeller-type stirrer.

[0091] Preferably, the agitator's impeller is located at the bottom of the reactor.

[0092] Preferably, a hydrogen peroxide distributor is provided at the hydrogen peroxide inlet of the reactor to disperse the hydrogen peroxide. The type of hydrogen peroxide distributor can be any conventional choice in the art, as long as it can achieve the above-mentioned function. For example, it can be a loop type, branch type, or nozzle type, etc., preferably a loop type.

[0093] In this invention, the reactor can be a single reactor or multiple reactors connected in series, and the appropriate choice can be made according to the actual situation.

[0094] When multiple reactors are used in series, hydrogen peroxide is fed in a multi-stage feeding method with simultaneous feeding.

[0095] In this invention, the catalyst separator is divided into an organic phase section and an aqueous phase section. The organic phase in the organic phase section is sent to the downstream product tank, and the aqueous phase in the aqueous phase section is returned to the reactor for reuse after being filtered by the downstream / internal membrane filter of the catalyst separator.

[0096] The present invention allows for a wide range of choices of membrane filters, wherein the membrane filter is composed of one or more membrane modules, which are connected in parallel and / or in series.

[0097] When the membrane filter is installed downstream of the catalyst separator, each membrane module consists of a housing, tube sheet, end caps, and one or more membrane tubes. When there are multiple membrane tubes, they are placed in parallel within the housing. Tube sheets are provided at both ends of the membrane tubes to separate the materials inside and outside the tubes. The aqueous phase containing the catalyst passes through the center of the membrane tube and permeates into the membrane module housing from the inside of the tube, resulting in a clarified liquid. The clarified liquid is discharged through a clarified liquid outlet line on the housing side. Preferably, a backwashing line is also provided on the clarified liquid outlet line on the housing side for backwashing the membrane tubes. More preferably, the medium for backwashing is the obtained clarified liquid. The remaining clarified liquid is sent to a downstream wastewater tank.

[0098] When a membrane filter is installed inside a catalyst separator, the membrane module includes one or more membrane tubes. One end of the membrane tube is closed, and the other end is connected to a collecting pipe. The aqueous phase containing the catalyst permeates from the outer surface of the membrane tube to the inner surface of the membrane tube to obtain a clear liquid, which is collected by the collecting pipe and discharged. A backwashing line is provided on the clear liquid discharge line, and the backwash liquid is the filtered clear liquid.

[0099] According to a specific embodiment of the present invention, refer to Figure 1The mixed slurry obtained by mixing cyclohexanone 1, ammonia 2 and the circulating catalyst slurry is fed into reactor 4 and reacted with hydrogen peroxide 3 to obtain reaction slurry 5 (a reaction slurry containing cyclohexanone oxime, ammonia, water and catalyst).

[0100] The reaction slurry 5 is mixed with the organic solvent 6 via pipeline, heated by the heat exchanger 7, and then sent to the catalyst separator 8 for catalyst separation, yielding an organic phase 9 (an organic phase containing cyclohexanone oxime and organic solvent) and an aqueous phase 10 (an aqueous phase containing catalyst). The aqueous phase section of the catalyst separator 8 is equipped with a stirrer to agitate the aqueous phase 10. The aqueous phase 10 is then sent to the downstream membrane separator 11 for filtration to separate a portion of the clarified liquid 13, after which the catalyst-rich stream 12 is returned to the reactor 4 for reuse. The organic phase 9 is then sent to the downstream product tank.

[0101] The membrane filter can also be installed in the aqueous phase section of the catalyst separator 8, as can be referred to... Figure 2 The aqueous phase 10 is filtered in the membrane separator 11 in the aqueous phase section of the catalyst separator 8 to separate a portion of the clear liquid 13, and then the catalyst-rich stream 12 is returned to the reactor 4 for reuse.

[0102] The present invention will be described in detail below through embodiments.

[0103] In the following examples, ketone conversion, oxime selectivity, and catalyst consumption were calculated using the following formulas:

[0104]

[0105]

[0106]

[0107] Wherein, w% - the mass percentage of the component in the organic phase output of the catalyst separator; 0.867 - the molecular weight ratio of cyclohexanone and cyclohexanone oxime; m (catalyst) - the total amount of catalyst added, g; F (ketone) - the cyclohexanone feed rate, kg / h; t - the unit operating time, h;

[0108] When calculating catalyst consumption, the ketone conversion and oxime selectivity are algebraic averages of the initial and final conversions and selectivities.

[0109] Example 1

[0110] 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 hydrogen peroxide distributor. The reaction is carried out at 90°C and 0.4 MPaG. The effective volume of the reactor is 3.0 L. The feed rates are: cyclohexanone 353 g / h, ammonia 67 g / h, hydrogen peroxide (35 wt%) 402 g / h, and circulating catalyst slurry flow rate is 6250 g / h. The mass fraction of cyclohexanone oxime in the circulating catalyst slurry is 1.5%, and the mass fraction of TS-1 titanium-silicon molecular sieve catalyst is 2.5%. The reaction product slurry is mixed with toluene and cooled to 70°C before being fed into a catalyst separator. The toluene flow rate is 810 g / h, and the mass flow rate ratio of toluene to cyclohexanone oxime is 2:1. The organic phase separated in the catalyst separator is sent to a product tank, and the aqueous phase is sent to a membrane filter. The filtered turbid liquid, which is the catalyst-rich stream, is recycled back to the reactor, and the filtered clear liquid is sent to a wastewater tank. See flowchart Figure 1 .

[0111] The reactor is equipped with a stirrer, which is a propeller-type stirrer with a rotation speed of 600 rpm.

[0112] The catalyst separator 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 upper and lower tangents 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 annular space formed by the inner sleeve and the inner extension tube is at the top... The vessel is partially enclosed, with the length ratio of the inner extension tube to the inner sleeve being 15:1. A gas phase balance port is provided on the side wall of the inner extension tube, which is connected to the gas phase space of the vessel body to ensure gas phase balance. The stirring paddle of the stirrer is located in the water phase section of the vessel body. An anti-surge baffle is provided at the bottom end of the inner extension tube. The vessel body is also provided with an overflow weir (L-shaped plate, one end of which is connected to the inner wall of the vessel body) and an organic phase outlet connected to the overflow weir. A water phase outlet is provided at the bottom of the vessel body, and a gas phase outlet is provided at the top of the vessel body.

[0113] The operating conditions inside the catalyst separator are: temperature 69℃, pressure 0.4MPaG; the agitator inside the catalyst separator is an anchor agitator with a rotation speed of 180rpm.

[0114] The membrane filter contains a sintered metal membrane tube with a diameter of 10 mm and a length of 200 mm. The filtration accuracy is 0.2 μm, and the backwash medium is the filtered clear liquid.

[0115] 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). Subsequently, the organic phase output from the catalyst separator was sampled and analyzed 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 and selectivity at this point are the final conversion rate and selectivity. The unit operating time was recorded, and catalyst consumption was calculated. Gas chromatography was used for analysis. The conversion rate, selectivity, catalyst consumption, cyclohexanone oxime product purity, and unit operating time data are shown in Table 1.

[0116] Example 2

[0117] The method described in Example 1 is different except that the feed rate of the circulating catalyst slurry is adjusted from 6250 g / h to 5750 g / h.

[0118] 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). Subsequently, the organic phase output from the catalyst separator was sampled and analyzed 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 and selectivity at this point are the final conversion rate and selectivity. The unit operating time was recorded, and catalyst consumption was calculated. Gas chromatography was used for analysis. The conversion rate, selectivity, catalyst consumption, cyclohexanone oxime product purity, and unit operating time data are shown in Table 1.

[0119] Example 3

[0120] 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 hydrogen peroxide distributor. The reaction is carried out at 95°C and 0.4 MPaG. The effective volume of the reactor is 3.0 L. The feed rates are: cyclohexanone 353 g / h, ammonia 67 g / h, hydrogen peroxide (35 wt%) 402 g / h, and circulating catalyst slurry flow rate is 6250 g / h. The mass fraction of cyclohexanone oxime in the circulating catalyst slurry is 1.5%, and the mass fraction of TS-1 titanium-silicon molecular sieve catalyst is 2.5%. The reaction product slurry is mixed with toluene and cooled to 70°C before being fed into a catalyst separator. The toluene flow rate is 810 g / h, and the mass flow rate ratio of toluene to cyclohexanone oxime is 2:1. The organic phase separated in the catalyst separator is sent to a product tank, and the aqueous phase is sent to a membrane filter. The filtered turbid liquid, which is the catalyst-rich stream, is recycled back to the reactor, and the filtered clear liquid is sent to a wastewater tank. See flowchart Figure 1 .

[0121] The reactor is equipped with a stirrer, which is a propeller-type stirrer with a rotation speed of 600 rpm.

[0122] The catalyst separator 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 upper and lower tangents 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 top of the annular space formed by the inner sleeve and the inner extension tube... The vessel is enclosed, with the length ratio of the inner extension tube to the inner sleeve being 15:1. A gas phase balance port is provided on the side wall of the inner extension tube, which is connected to the gas phase space of the vessel body to ensure gas phase balance. The stirring paddle of the stirrer is located in the water phase section of the vessel body. An anti-surge baffle is provided at the bottom end of the inner extension tube. The vessel body is also provided with an overflow weir (L-shaped plate, one end of which is connected to the inner wall of the vessel body) and an organic phase outlet connected to the overflow weir. A water phase outlet is provided at the bottom of the vessel body, and a gas phase outlet is provided at the top of the vessel body.

[0123] The operating conditions inside the catalyst separator are: temperature 69℃, pressure 0.4MPaG; the agitator inside the catalyst separator is an anchor agitator with a rotation speed of 180rpm.

[0124] The membrane filter contains a sintered metal membrane tube with a diameter of 10 mm and a length of 200 mm. The filtration accuracy is 0.2 μm, and the backwash medium is the filtered clear liquid.

[0125] 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). Subsequently, the organic phase output from the catalyst separator was sampled and analyzed 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 and selectivity at this point are the final conversion rate and selectivity. The unit operating time was recorded, and catalyst consumption was calculated. Gas chromatography was used for analysis. The conversion rate, selectivity, catalyst consumption, cyclohexanone oxime product purity, and unit operating time data are shown in Table 1.

[0126] Example 4

[0127] 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 hydrogen peroxide distributor. The reaction is carried out at 90°C and 0.4 MPaG. The effective volume of the reactor is 3.0 L. The feed rates are: cyclohexanone 353 g / h, ammonia 67 g / h, hydrogen peroxide (35 wt%) 402 g / h, and circulating catalyst slurry flow rate is 6250 g / h. The mass fraction of cyclohexanone oxime in the circulating catalyst slurry is 1.5%, and the mass fraction of TS-1 titanium-silicon molecular sieve catalyst is 2%. The reaction product slurry is mixed with toluene and cooled to 70°C before being fed into a catalyst separator. The toluene flow rate is 810 g / h, and the mass flow rate ratio of toluene to cyclohexanone oxime is 2:1. The organic phase separated in the catalyst separator is sent to a product tank, and the aqueous phase is sent to a membrane filter. The filtered turbid liquid, which is the catalyst-rich stream, is recycled back to the reactor, and the filtered clear liquid is sent to a wastewater tank. See flowchart Figure 1 .

[0128] The reactor is equipped with a stirrer, which is a propeller-type stirrer with a rotation speed of 600 rpm.

[0129] The catalyst separator 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 upper and lower tangents 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 annular space formed by the inner sleeve and the inner extension tube is at the top... The vessel is partially enclosed, with the length ratio of the inner extension tube to the inner sleeve being 15:1. A gas phase balance port is provided on the side wall of the inner extension tube, which is connected to the gas phase space of the vessel body to ensure gas phase balance. The stirring paddle of the stirrer is located in the water phase section of the vessel body. An anti-surge baffle is provided at the bottom end of the inner extension tube. The vessel body is also provided with an overflow weir (L-shaped plate, one end of which is connected to the inner wall of the vessel body) and an organic phase outlet connected to the overflow weir. A water phase outlet is provided at the bottom of the vessel body, and a gas phase outlet is provided at the top of the vessel body.

[0130] The operating conditions inside the catalyst separator are: temperature 69℃, pressure 0.4MPaG; the agitator inside the catalyst separator is an anchor agitator with a rotation speed of 180rpm.

[0131] The membrane filter contains a sintered metal membrane tube with a diameter of 10 mm and a length of 200 mm. The filtration accuracy is 0.2 μm, and the backwash medium is the filtered clear liquid.

[0132] 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). Subsequently, the organic phase output from the catalyst separator was sampled and analyzed 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 and selectivity at this point are the final conversion rate and selectivity. The unit operating time was recorded, and catalyst consumption was calculated. Gas chromatography was used for analysis. The conversion rate, selectivity, catalyst consumption, cyclohexanone oxime product purity, and unit operating time data are shown in Table 1.

[0133] Example 5

[0134] 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°C and 0.4 MPaG. The effective volume of the reactor is 3.0 L. The feed rates are as follows: cyclohexanone feed rate is 353 g / h, ammonia feed rate is 67 g / h, hydrogen peroxide (hydrogen peroxide concentration of 35 wt%) feed rate is 402 g / h, and circulating catalyst slurry feed rate is 6250 g / h. The mass fraction of cyclohexanone oxime in the circulating catalyst slurry is 1.5%, and the mass fraction of TS-1 titanium-silicon molecular sieve catalyst in the circulating catalyst slurry is 2.5%. The resulting reaction product slurry is mixed with toluene and cooled to 70°C before being fed into a catalyst separator. The toluene flow rate is 810 g / h, and the mass ratio of toluene to cyclohexanone oxime in the reaction product is 2:1. The organic phase separated by the catalyst separator is sent to a downstream storage tank. The catalyst separator's aqueous phase space is equipped with a 10mm diameter, 100mm long sintered metal membrane tube with a filtration accuracy of 0.2μm. The backwash medium is the filtered clear liquid. The clear liquid obtained in the filter tube is sent to the wastewater tank, while the filtered aqueous phase, which is the catalyst-rich stream, is recycled back to the reactor. See the process diagram below. Figure 2 .

[0135] The catalyst separator 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 upper and lower tangents 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 top of the annular space formed by the inner sleeve and the inner extension tube... The vessel is enclosed, with the length ratio of the inner extension tube to the inner sleeve being 15:1. A gas phase balance port is provided on the side wall of the inner extension tube, which is connected to the gas phase space of the vessel body to ensure gas phase balance. The stirring paddle of the stirrer is located in the water phase section of the vessel body. An anti-surge baffle is provided at the bottom end of the inner extension tube. The vessel body is also provided with an overflow weir (L-shaped plate, one end of which is connected to the inner wall of the vessel body) and an organic phase outlet connected to the overflow weir. A water phase outlet is provided at the bottom of the vessel body, and a gas phase outlet is provided at the top of the vessel body.

[0136] 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). Subsequently, the organic phase output from the catalyst separator was sampled and analyzed 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 and selectivity at this point are the final conversion rate and selectivity. The unit operating time was recorded, and catalyst consumption was calculated. Gas chromatography was used for analysis. The conversion rate, selectivity, catalyst consumption, cyclohexanone oxime product purity, and unit operating time data are shown in Table 1.

[0137] Example 6

[0138] 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 hydrogen peroxide distributor. The reaction is carried out at 90°C and 0.4 MPaG. The effective volume of the reactor is 3.0 L. The feed rates are: cyclohexanone 353 g / h, ammonia 67 g / h, hydrogen peroxide (35 wt%) 402 g / h, and circulating catalyst slurry flow rate is 5600 g / h. The mass fraction of cyclohexanone oxime and TS-1 titanium-silicon molecular sieve catalyst in the circulating catalyst slurry is 2.5%. The reaction product slurry is mixed with toluene and cooled to 70°C before being fed into a catalyst separator. The toluene flow rate is 400 g / h, and the mass flow rate ratio of toluene to cyclohexanone oxime is 1:1. The organic phase separated in the catalyst separator is sent to a product tank, and the aqueous phase is sent to a membrane filter. The filtered turbid liquid, which is the catalyst-rich stream, is recycled back to the reactor, and the filtered clear liquid is sent to a wastewater tank. See flowchart Figure 1 .

[0139] The reactor is equipped with a stirrer, which is a propeller-type stirrer with a rotation speed of 600 rpm.

[0140] The catalyst separator 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 upper and lower tangents 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 annular space formed by the inner sleeve and the inner extension tube is at the top... The vessel is partially enclosed, with the length ratio of the inner extension tube to the inner sleeve being 15:1. A gas phase balance port is provided on the side wall of the inner extension tube, which is connected to the gas phase space of the vessel body to ensure gas phase balance. The stirring paddle of the stirrer is located in the water phase section of the vessel body. An anti-surge baffle is provided at the bottom end of the inner extension tube. The vessel body is also provided with an overflow weir (L-shaped plate, one end of which is connected to the inner wall of the vessel body) and an organic phase outlet connected to the overflow weir. A water phase outlet is provided at the bottom of the vessel body, and a gas phase outlet is provided at the top of the vessel body.

[0141] The operating conditions inside the catalyst separator are: temperature 69℃, pressure 0.4MPaG; the agitator inside the catalyst separator is an anchor agitator with a rotation speed of 180rpm.

[0142] The membrane filter contains a sintered metal membrane tube with a diameter of 10 mm and a length of 200 mm. The filtration accuracy is 0.2 μm, and the backwash medium is the filtered clear liquid.

[0143] 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). Subsequently, the organic phase output from the catalyst separator was sampled and analyzed 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 and selectivity at this point are the final conversion rate and selectivity. The unit operating time was recorded, and catalyst consumption was calculated. Gas chromatography was used for analysis. The conversion rate, selectivity, catalyst consumption, cyclohexanone oxime product purity, and unit operating time data are shown in Table 1.

[0144] Comparative Example 1

[0145] The method described in Example 1 is different in that hydrogen peroxide is mixed with cyclohexanone, ammonia and circulating catalyst slurry and then fed into the reactor, with the circulating catalyst slurry volume being 2700 g / h.

[0146] 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). Subsequently, the organic phase output from the catalyst separator was sampled and analyzed 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 and selectivity at this point are the final conversion rate and selectivity. The unit operating time was recorded, and catalyst consumption was calculated. Gas chromatography was used for analysis. The conversion rate, selectivity, catalyst consumption, cyclohexanone oxime product purity, and unit operating time data are shown in Table 1.

[0147] Table 1

[0148]

[0149] As can be seen from the results in Table 1, compared with the comparative example, the embodiments of the present invention have significantly higher cyclohexanone conversion and cyclohexanone oxime selectivity; at the same time, the catalyst consumption is significantly less, which can significantly improve the catalyst's service life.

[0150] The preferred 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 combinations of 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 cyclohexanone oxime, characterized in that, The method includes the following steps: (1) Cyclohexanone, ammonia and circulating catalyst slurry are mixed and then reacted with hydrogen peroxide to obtain a reaction slurry containing cyclohexanone oxime, ammonia, water and catalyst; wherein, the feed cyclohexanone accounts for 2-6% of the total mass of cyclohexanone and circulating catalyst slurry. (2) The reaction slurry and the organic solvent are mixed to obtain a mixed slurry; the mixed slurry is subjected to two-phase separation to obtain an organic phase containing cyclohexanone oxime and organic solvent and an aqueous phase containing catalyst; wherein the mass ratio of organic solvent to cyclohexanone oxime in the reaction slurry is 0.5-5:1; (3) The aqueous phase containing the catalyst is subjected to membrane filtration to obtain a clear liquid and a catalyst-rich stream; the catalyst-rich stream is returned to the circulating catalyst slurry provided in step (1); Wherein, the reaction slurry is heated and then mixed with an organic solvent; and / or, The mixed slurry is heated and then subjected to two-phase separation; and / or, The aqueous phase containing the catalyst is heated and then subjected to membrane filtration; and / or, The catalyst-rich stream is heated and then returned to step (1) for reuse.

2. The method according to claim 1, wherein, The feed cyclohexanone accounts for 3-5.5% of the total mass of cyclohexanone and the circulating catalyst slurry; Preferably, the mass fraction of cyclohexanone oxime in the circulating catalyst slurry is 0.1-4%, more preferably 0.5-3%.

3. The method according to claim 1, wherein, The reaction temperature in step (1) is 70-100℃, preferably 80-95℃; the reaction pressure is 0-0.5MPaG, preferably 0.2-0.4MPaG. Preferably, the molar ratio of hydrogen peroxide to cyclohexanone is 1-1.5:1; Preferably, the molar ratio of ammonia to cyclohexanone is 1-1.5:1; Preferably, the mass fraction of the catalyst in the circulating catalyst slurry is 0.1-15%, more preferably 1-10%; 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 molecular sieves.

4. The method according to any one of claims 1-3, wherein, The organic solvent is at least one of alkanes having 6-12 carbon atoms, cycloalkanes having 5-11 carbon atoms, and aromatics having 6-10 carbon atoms, preferably at least one of aromatics having 6-10 carbon atoms and cycloalkanes having 6-10 carbon atoms, and more preferably toluene and / or cyclohexane.

5. The method according to any one of claims 1-4, wherein, The operating conditions for the two-phase separation in step (2) include: temperature of 40-90℃ and pressure of 0-0.5MPaG.

6. The method according to any one of claims 1-5, wherein, The two-phase separation in step (2) is carried out in a catalyst separator; the catalyst separator preferably includes a vessel body and a stirrer, an inner extension tube and an inner sleeve disposed in the vessel body; The inner sleeve is fitted inside the inner extension tube, and the inner sleeve is used to transport the mixed slurry of reaction slurry and organic solvent to the inner extension tube; The inner tube is used to transport the mixture of reaction slurry and organic solvent to the reactor body for two-phase separation to obtain an organic phase and an aqueous phase; 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; The agitator's stirring paddle is positioned within the aqueous phase section of the vessel and is used to agitate the aqueous phase.

7. The method according to claim 6, wherein, A gas phase balance port is provided on the side wall of the inner tube to maintain the gas phase balance of the vessel body; Preferably, the top of the annular space formed by the inner sleeve and the inner extension tube is closed; Preferably, the ratio of the length of the inner sleeve to the length of the inner extension tube is 5-30:1; Preferably, 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, the bottom end of the inner tube is provided with an anti-impact baffle, which is used to buffer the mixture of reaction slurry and organic solvent.

8. The method according to any one of claims 1-7, wherein, The membrane used in step (3) for membrane filtration is selected from at least one of ceramic membranes, metal membranes and polyethylene membranes, and more preferably metal membranes; Preferably, the membrane used in step (3) has a filtration accuracy of 0.01-50 micrometers.

9. The method according to any one of claims 1-8, wherein, The heat extraction ensures that the temperature of the catalyst-rich stream returned to step (1) is 40-90°C; Preferably, the circulating catalyst slurry comprises the catalyst-rich stream obtained in step (3) and optionally a slurry containing fresh catalyst.

10. A system for preparing cyclohexanone oxime according to any one of claims 1-9, the system comprising a reactor, a heat exchanger, a catalyst separator and a membrane filter connected in sequence; The aqueous phase outlet of the catalyst separator is connected to the inlet of the membrane filter; The catalyst outlet of the membrane filter is connected to the circulating catalyst inlet of the reactor.

11. A system for the preparation method of cyclohexanone oxime according to any one of claims 1-9, the system comprising a reactor, a heat exchanger and a catalyst separator connected in sequence; A membrane filter is installed in the aqueous phase section of the catalyst separator, and the aqueous phase outlet of the catalyst separator is connected to the circulating catalyst inlet of the reactor.

12. The system according to claim 10 or 11, wherein, A hydrogen peroxide distributor is installed at the hydrogen peroxide inlet of the reactor to disperse the hydrogen peroxide.

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