Treatment method of cyclohexane oxidation liquid

Abstract

The invention belongs to the field of treatment of cyclohexane oxidation liquid, and particularly relates to a treatment method of cyclohexane oxidation liquid, which comprises the following steps: carrying out neutralization reaction on the cyclohexane oxidation liquid and alkali liquor A, and separating to obtain an oil phase A and a water phase A; the oil phase A is a cyclohexane solution enriched with cyclohexyl hydroperoxide, cyclohexanol and cyclohexanone; the alkali liquor A is an aqueous solution in which alkali carbonate is dissolved; carrying out decomposition reaction on the oil phase A and the alkali liquor B, and separating to obtain an oil phase B and a water phase B; the oil phase B is a cyclohexane solution enriched with cyclohexanol and cyclohexanone; the alkali liquor B is an aqueous solution in which alkali metal hydroxide is dissolved; wherein the neutralization reaction and / or the decomposition reaction are / is carried out in a fiber membrane reactor. The method provided by the invention has an excellent cyclohexane oxidation liquid treatment effect, and can reduce the alkali consumption in the decomposition process of the cyclohexane oxidation liquid and improve the decomposition yield.

Description

Technical Field

[0001] This invention belongs to the field of cyclohexanone preparation technology, specifically relating to a method for preparing cyclohexanol and cyclohexanone. Background Technology

[0002] The preparation of cyclohexanol and cyclohexanone typically involves oxidizing cyclohexane with a gas containing molecular oxygen. This first generates a cyclohexane oxidation liquid containing cyclohexyl hydrogen peroxide, cyclohexanol, cyclohexanone, and carboxylic acids. The cyclohexane oxidation liquid is then treated to decompose the cyclohexyl hydrogen peroxide into cyclohexanol and cyclohexanone. Unreacted cyclohexane is then distilled off and recycled. The reaction products are then subjected to multiple distillations to obtain cyclohexanol and cyclohexanone.

[0003] Cyclohexane oxidation typically employs a multi-reactor series process, with the cyclohexane conversion rate generally controlled between 3% and 4%, the cyclohexyl hydrogen peroxide content around 3%, and the selectivity of the target product approximately 92%.

[0004] Cyclohexane oxidation liquid containing approximately 3% cyclohexyl hydrogen peroxide is treated in a decomposition process. The cyclohexyl hydrogen peroxide decomposes into cyclohexanol and cyclohexanone, along with a small amount of byproducts. Currently, the most widely used method is to treat the cyclohexane oxidation liquid with an alkaline aqueous solution containing sodium hydroxide. During the decomposition of cyclohexyl hydrogen peroxide, the acids in the oxidation liquid are neutralized, and the esters are saponified. Therefore, the decomposition products, after sedimentation and separation of the alkaline aqueous phase, do not contain acidic substances and will not corrode subsequent equipment. However, this process requires approximately 440 kg / t of cyclohexanone solution (30%) and generates a large amount of saponification waste alkaline liquid.

[0005] Chinese patent CN1166602C proposes a method for preparing cyclohexanone and cyclohexanol from cyclohexane. After obtaining the cyclohexane oxidation liquid, the cyclohexane oxidation liquid is first treated with an aqueous solution of sodium carbonate obtained from the incineration of waste alkali to neutralize the carboxylic acid in the oxidation liquid. At the same time, some cyclohexyl hydrogen peroxide is decomposed. Then, the cyclohexyl hydrogen peroxide in the cyclohexane oxidation liquid is decomposed with sodium hydroxide solution. This reduces the consumption of sodium hydroxide during the decomposition process and realizes a closed-loop cycle of saponification waste alkali - incineration of sodium carbonate - saponification waste alkali.

[0006] Chinese patent CN1253938A proposes a method for preparing cyclohexanol and cyclohexanone. This method involves decomposing cyclohexyl hydrogen peroxide in a cyclohexane oxidation solution using an external alkali circulation system and a static mixer for pre-mixing followed by decomposition in a stirred tank. First, the cyclohexyl hydrogen peroxide is extracted from the organic phase to the alkaline aqueous phase, then decomposed into cyclohexanol and cyclohexanone in the alkaline aqueous phase, and finally extracted back into the organic phase. This method can improve the yield of cyclohexyl hydrogen peroxide decomposing into cyclohexanol and cyclohexanone.

[0007] Chinese patent CN1659122A proposes a method for high-yield decomposition of cyclohexyl hydrogen peroxide. The method involves first washing away some organic acids in the cyclohexane oxidation liquid with a small amount of water, and then decomposing the oxidation liquid with sodium hydroxide at a higher temperature and a higher phase ratio. The decomposition reactor is preferably a stirred tank, as sufficient stirring is beneficial to improving the efficiency of the decomposition reaction.

[0008] In the aforementioned patent, the decomposition of cyclohexyl hydrogen peroxide is generally carried out in a 2-3 stage series stirred tank reactor, where the cyclohexane phase and the alkaline aqueous phase can be fully mixed. However, the stirred tank reactor is equivalent to a fully mixed-flow reactor, where the concentration of each component in the reactor is equal to the concentration of each component in the effluent. In actual production, the concentration of cyclohexyl hydrogen peroxide at the outlet of the first-stage reactor has decreased by 70%, and even more than 90% at higher reaction temperatures. This indicates that the concentration of cyclohexyl hydrogen peroxide in the first-stage reactor is already low, the reaction rate is relatively slow, and the concentration of cyclohexanol and cyclohexanone in the cyclohexane phase is high, which is not conducive to the extraction of cyclohexanol and cyclohexanone from the alkaline aqueous phase after decomposition by cyclohexane. In the second and third stage reactors, the concentration of cyclohexyl hydrogen peroxide is close to zero, and the decomposition rate has been reduced to a minimum. At the same time, the concentrations of cyclohexanol and cyclohexanone in the cyclohexane phase have risen to a maximum. The rate at which cyclohexanol and cyclohexanone are extracted back into the alkaline aqueous phase after decomposition is also reduced to a minimum. Cyclohexanol and cyclohexanone will undergo condensation side reactions if they remain in the alkaline phase for a long time, which will reduce the yield of cyclohexanol and cyclohexanone.

[0009] In the aforementioned patent, a stirred tank is used to decompose cyclohexane oxidation liquid with sodium hydroxide solution. The oxidation liquid and sodium hydroxide solution are thoroughly mixed, and after the reaction is complete, the mixture is allowed to stand in a separation tank for separation. When the stirring intensity is weak, the contact between the two phases is not ideal, and some cyclohexyl hydrogen peroxide will not be decomposed, reducing the conversion rate of the decomposition process. When the stirring intensity is strong, the material will emulsify, making it difficult for the alkane phase and the basic phase to settle and separate completely. When the alkane phase carries a small amount of basic phase containing sodium hydroxide, it will cause slagging in the alkane tower when it enters the subsequent cyclohexane distillation process, requiring regular cleaning. Summary of the Invention

[0010] In view of the shortcomings of existing cyclohexane oxidation decomposition processes, the purpose of this invention is to provide a highly efficient method for treating cyclohexane oxidation liquid, aiming to improve the treatment effect of cyclohexane oxidation liquid.

[0011] A method for treating cyclohexane oxidation liquid involves neutralizing the cyclohexane oxidation liquid with an alkaline solution A to separate an oil phase A and an aqueous phase A; wherein the oil phase A is a cyclohexane solution enriched with cyclohexyl hydrogen peroxide, cyclohexanol, and cyclohexanone; and the alkaline solution A is an aqueous solution containing dissolved alkali metal carbonates.

[0012] Oil phase A and alkaline solution B are decomposed to separate oil phase B and aqueous phase B; oil phase B is a cyclohexane solution enriched with cyclohexanol and cyclohexanone; alkaline solution B is an aqueous solution containing alkali metal hydroxide.

[0013] The neutralization and / or decomposition reactions are carried out in a fiber membrane reactor.

[0014] To address the issues of unsatisfactory efficiency and effectiveness in the selective separation of cyclohexyl hydrogen peroxide and cyclohexanone in cyclohexane oxidation solutions, this invention innovatively conducts the aforementioned neutralization and / or decomposition reactions in a fiber membrane reactor. This unexpectedly improves the efficiency and effectiveness of the selective separation of cyclohexyl hydrogen peroxide and cyclohexanone, while also reducing alkali consumption, demonstrating excellent industrial application value.

[0015] In this invention, the cyclohexane oxidation liquid can be prepared by conventional means, for example, it can be an oxidation reaction liquid obtained by oxidizing cyclohexane.

[0016] The temperature during the oxidation treatment stage is 165–170℃; the pressure is 1–2 MPa.

[0017] In the cyclohexane oxidation solution, the content of cyclohexyl hydrogen peroxide is 1-5 v%; the content of cyclohexanol is 0.1-1.5 v%; the content of cyclohexanone is 0.1-1 v%; and the content of carboxylic acid impurities is 0.1-0.6 v%.

[0018] In alkaline solution A, the alkali metal carbonate is sodium carbonate, and the concentration of the solute is 1% to 30%.

[0019] During the neutralization reaction stage, the ratio of cyclohexane oxidation liquid to alkaline solution A is 2 to 20:1.

[0020] In alkaline solution B, the alkali metal hydroxide solution is an aqueous solution of sodium hydroxide with a concentration of 1% to 10%.

[0021] In this invention, the ratio of oil phase A to alkaline solution B in the decomposition reaction stage is 2 to 20:1.

[0022] During the neutralization reaction stage of the fiber membrane reactor, the temperature inside the reactor is controlled at 50–100℃ and the pressure is absolute at 0.1–1.0 MPa.

[0023] During the decomposition reaction stage of the fiber membrane reactor, the temperature inside the reactor is controlled at 70–120℃ and the pressure is absolute at 0.1–1.0 MPa.

[0024] In this invention, the fiber membrane reactor can be a conventional fiber membrane reactor. For example, the main body of the fiber membrane reactor includes a fiber membrane contactor and a separation tank. The fiber membrane contactor is composed of metal fiber filaments, which are wrapped in a cylindrical sleeve and extend out of the sleeve to the alkaline water phase at the bottom of the separation tank.

[0025] In this invention, the cyclohexane oxidation liquid and alkali solution A enter from the top of the fiber membrane contactor. Alkali solution A flows downward in a film-like manner along the outer surface of the metal fibers, while the cyclohexane oxidation liquid flows downward in the gaps between the metal fibers. At the same time, the carboxylic acid in the cyclohexane oxidation liquid undergoes a neutralization reaction with the downward-flowing alkali solution A and is separated in a separation tank. The upper layer is the oil phase A, which then enters the decomposition reactor to continue the reaction; the lower layer is the aqueous phase A.

[0026] In this invention, the oil phase A and the alkaline solution B enter from the top of the fiber membrane contactor. The alkaline solution B flows downward in a film-like manner along the outer surface of the metal fiber filaments, while the oil phase A flows downward in the gaps between the metal fiber filaments. At the same time, the cyclohexyl hydrogen peroxide in the oil phase A undergoes a decomposition reaction with the downward-flowing alkaline solution B and is separated in a separation tank. The upper layer is the oil phase B, which is then further washed with water and enters the alkylation tower for separation; the lower layer is the aqueous phase B.

[0027] In this invention, the aqueous phase A is divided into two parts, A1 and A2. A1 is circulated in the reactor for the neutralization reaction, and A2 is obtained by countercurrent extraction with cyclohexane to obtain oil phase C and aqueous phase C. The oil phase C is a cyclohexane solution enriched with cyclohexyl hydrogen peroxide, cyclohexanol and cyclohexanone, which is mixed with oil phase A and then enters the reactor for the decomposition reaction. The aqueous phase C is an aqueous solution of alkali metal carbonate containing carboxylates.

[0028] The aqueous phase B is divided into three parts: B1, B2, and B3. B1 is circulated in the reactor for the decomposition reaction. B2 is mixed with A1 and then circulated in the reactor for the neutralization reaction. B3 is concentrated together with the aqueous phase C in the waste alkali evaporation tower and then sent to the waste alkali incineration unit for incineration. The evaporated portion is introduced into the B2 stream.

[0029] In this invention, the aqueous phase A is contacted with cyclohexane in a countercurrent extraction tower, and the extracted organic phase is returned to the cyclohexane oxidation liquid.

[0030] In this invention, the oil phase B can be washed with water and then subjected to distillation to obtain cyclohexanol and cyclohexanone.

[0031] Compared with the prior art, the technical solution of the present invention brings the following beneficial technical effects:

[0032] 1) The cyclohexane oxidation liquid is treated by a fiber membrane reactor, which integrates the reaction and separation, simplifies the process and improves the efficiency of reaction and separation.

[0033] 2) In the fiber membrane decomposition reactor, the alkane phase containing peroxide and the aqueous phase containing sodium hydroxide are in co-current contact. The two materials are in a plug flow state. Compared with the completely mixed flow, the concentration of cyclohexyl hydrogen peroxide in the alkane phase is higher and the concentration of cyclohexanol and cyclohexanone is lower. The rate at which cyclohexyl hydrogen peroxide is transferred to the alkaline phase and the reaction rate of cyclohexyl hydrogen peroxide in the alkaline phase are faster. The rate at which cyclohexanol and cyclohexanone are extracted from the alkaline phase back to the alkane phase is also faster, which improves the overall reaction efficiency.

[0034] 3) In the fiber membrane decomposition reactor, the alkane phase containing cyclohexyl hydrogen peroxide and the aqueous phase containing sodium hydroxide are in membrane contact, which increases the mass transfer area and thus increases the mass transfer rate. The extraction rate of cyclohexyl hydrogen peroxide to the alkaline phase is accelerated. At the same time, the extraction rate of cyclohexanol and cyclohexanone generated after the reaction back to the alkane phase is also faster, which reduces the residence time of cyclohexanol and cyclohexanone in the alkaline phase and reduces the condensation rate of cyclohexanol and cyclohexanone.

[0035] 4) In the fiber membrane reactor, the alkane phase and the alkaline water phase are in membrane contact, which increases the mass transfer area and avoids emulsification caused by excessive mixing between the two phases, thus reducing the occurrence of alkane phase carrying alkali and alkaline water phase carrying alkane.

[0036] 5) After separating the aqueous sodium carbonate phase, cyclohexane extraction can be used to extract the cyclohexyl hydrogen peroxide, cyclohexanol and cyclohexanone dissolved in the aqueous sodium carbonate phase into cyclohexane, and the content of useful products in the aqueous sodium carbonate phase can be reduced to below 0.1%.

[0037] Compared with existing technologies, the present invention uses a fiber membrane reactor to treat cyclohexane oxidation liquid, which reduces the number of devices, increases the reaction rate, improves the separation efficiency of the alkane phase and the basic phase, and can also increase the total yield of cyclohexanol and cyclohexanone. Attached Figure Description

[0038] 【 Figure 1 [Image caption: Schematic diagram of the cyclohexane oxidation liquid treatment process;]

[0039] 【 Figure 2 [Image: Schematic diagram of fiber membrane reactor process] Detailed Implementation

[0040] The method for treating cyclohexane oxidation liquid includes the following steps:

[0041] 1) The cyclohexane oxidation solution and alkaline solution A are neutralized to separate oil phase A and aqueous phase A; the cyclohexane oxidation solution is a cyclohexane solution containing cyclohexyl hydrogen peroxide, cyclohexanol, cyclohexanone and carboxylic acid, obtained by oxidizing cyclohexane with oxygen-containing gas; the alkaline solution A is an aqueous solution of alkali metal carbonate containing carboxylates; the oil phase A is a cyclohexane solution enriched with cyclohexyl hydrogen peroxide, cyclohexanol and cyclohexanone; and the aqueous phase A is an aqueous solution of alkali metal carbonate enriched with carboxylates.

[0042] 2) The oil phase A and the alkaline solution B are decomposed to separate the oil phase B and the aqueous phase B; the alkaline solution B is an aqueous solution of alkali metal hydroxide containing carboxylates, the oil phase B is a cyclohexane solution enriched with cyclohexanol and cyclohexanone, and the aqueous phase B is an aqueous solution of alkali metal hydroxide containing carboxylates.

[0043] 3) The oil phase B is further washed with water and then separated by distillation to obtain a mixture of cyclohexanol and cyclohexanone, and cyclohexane;

[0044] 4) The aqueous phase A is divided into two parts, A1 and A2. A1 is circulated in the neutralization reactor, and A2 is extracted with cyclohexane through countercurrent extraction to obtain oil phase C and aqueous phase C. The oil phase C is a cyclohexane solution enriched with cyclohexyl hydrogen peroxide, cyclohexanol and cyclohexanone. After being mixed with oil phase A, it enters the decomposition reactor. The aqueous phase C is an aqueous solution of alkali metal carbonate containing carboxylates.

[0045] 5) The aqueous phase B is divided into three parts: B1, B2 and B3. B1 is circulated in the decomposition reactor. B2 is mixed with A1 and then participates in the neutralization reactor circulation. B3 is concentrated together with the aqueous phase C in the waste alkali evaporation tower and then sent to the waste alkali incineration unit for incineration. The evaporated part is introduced into the B2 stream.

[0046] The neutralization and / or decomposition reactions are carried out in a fiber membrane reactor.

[0047] The main body of the fiber membrane reactor includes a fiber membrane contactor and a separation tank. The fiber membrane contactor is composed of multiple metal fiber filaments, which are wrapped in a cylindrical sleeve and extend out of the sleeve to the alkaline water phase at the bottom of the separation tank.

[0048] Step 1) The cyclohexane oxidation solution and alkali solution A enter from the top of the fiber membrane contactor. Alkali solution A flows downward in a film-like manner along the outer surface of the metal fibers, while the cyclohexane oxidation solution flows downward in the gaps between the metal fibers. At the same time, the carboxylic acid in the cyclohexane oxidation solution undergoes a neutralization reaction with the downward-flowing alkali solution A and is separated in the separation tank. The upper layer is the cyclohexane phase with a lower density. Most of the cyclohexyl hydrogen peroxide, cyclohexanol, and cyclohexanone in the cyclohexane oxidation solution remain in the cyclohexane phase and then enter the decomposition reactor to continue the reaction. The lower layer is the alkali metal carbonate water phase with a higher density. The alkali metal carboxylates formed by the reaction of carboxylic acid in the cyclohexane oxidation solution with alkali metal carbonates dissolve in the aqueous phase. At the same time, a small amount of cyclohexyl hydrogen peroxide, cyclohexanol, and cyclohexanone also dissolve in the aqueous phase.

[0049] Step 2) The oil phase A and alkali solution B enter from the top of the fiber membrane contactor. The alkali solution B flows downward in a film along the outer surface of the metal fiber filaments, while the oil phase A flows downward in the gaps between the metal fiber filaments. At the same time, the cyclohexyl hydrogen peroxide in the oil phase A undergoes a decomposition reaction with the downward-flowing alkali solution B and is separated in the separation tank. The upper layer is a cyclohexane phase with a lower density, in which most of the cyclohexanol and cyclohexanone remain. After further washing with water, it enters the alkane tower for separation. The lower layer is an aqueous phase of alkali metal hydroxide with a higher density. A small amount of water-soluble substances generated during the decomposition process dissolve in the aqueous alkali phase.

[0050] The aqueous phase A is contacted with cyclohexane in a countercurrent extraction tower. Organic compounds that are not easily soluble in water, such as cyclohexyl hydrogen peroxide, cyclohexanol, and cyclohexanone dissolved in the aqueous phase, are extracted into the cyclohexane and then returned to the cyclohexane oxidation liquid.

[0051] In alkaline solution A, the alkali metal carbonate is sodium carbonate, and the concentration of the solute is 1% to 30%.

[0052] During the neutralization reaction stage, the ratio of cyclohexane oxidation liquid to alkaline solution A is 2 to 20:1.

[0053] In alkaline solution B, the alkali metal hydroxide solution is an aqueous solution of sodium hydroxide with a concentration of 1% to 10%.

[0054] During the decomposition reaction stage, the ratio of oil phase A to alkaline solution B is 2 to 20:1.

[0055] During the neutralization reaction stage of the fiber membrane reactor, the temperature inside the reactor is controlled at 50–100℃ and the pressure is absolute at 0.1–1.0 MPa.

[0056] During the decomposition reaction stage of the fiber membrane reactor, the temperature inside the reactor is controlled at 70–120℃ and the pressure is absolute at 0.1–1.0 MPa.

[0057] The following embodiments are intended to further illustrate the present invention in conjunction with the accompanying drawings, and are not intended to limit the scope of protection of the claims of the present invention.

[0058] Figure 1 This is a flow chart of materials for the decomposition of cyclohexyl hydrogen peroxide, where R1 is the neutralization reactor, S1 is the neutralization separation tank, C1 is the alkaline water extraction tower, R2 is the decomposition reactor, S2 is the decomposition separation tank, and C2 is the waste alkali evaporation tower.

[0059] The oxidizing liquid is connected to the inlet of pump 01 and R1, the carbonate alkali liquid is connected to the inlet of pump 15 and R1, and the organic phase of the S1 separator is connected to the inlet of pump 11 / 21 and R2. The aqueous phase A outlet of the S1 separator is connected to the inlet of pump 12, 13 and C1. A carbonate recycling bypass is also provided between the pipelines of pump 12 and 13, which is connected in series through the inlets of pump 14 and pump 15 for carbonate recycling.

[0060] The C1 alkaline water extraction tower is also equipped with a cyclohexane inlet, which is connected to the output port of the cyclohexane transfer pump 03; the aqueous phase outlet of the C1 alkaline water extraction tower is connected to the C2 inlet via the transfer pump 16.

[0061] The organic phase outlet of C1 is connected to the connecting pipeline of transfer pumps 11 and 21 via transfer pump 17;

[0062] R2 also involves an alkali inlet, and the new alkali storage tank is connected to the alkali inlet of R2 via transfer pump 02; the oil phase B outlet of S2 is connected to the water washing tank via transfer pump 22; one part of the aqueous phase B outlet of R2 is connected to the alkali inlet of R2 via transfer pumps 24 and 25, and the other part is connected via the pipeline between transfer pump 25 and transfer pumps 14 and 15; another part of the aqueous phase B outlet of R2 is connected to C2 via transfer pump 26; the outlet of C2 is connected to the waste alkali incineration device via transfer pump 28; and the outlet of C2 is connected to the connecting pipeline between 14 and 15 via transfer pump 27.

[0063] It should be noted that, in order to simplify the process and reduce costs, the aforementioned delivery pump can also be replaced with a flow control valve.

[0064] Figure 2 Schematic diagram of the fiber membrane neutralization / decomposition process.

[0065] R1—Fiber membrane contactor, DN50*2400; S1—Alkane-alkali separation tank, DN250*1000;

[0066] V1—New alkali (sodium carbonate / sodium hydroxide) preparation tank; S1 pressure is manually controlled by the discharge valve;

[0067] All equipment and pipelines are insulated, and the reaction temperature is controlled by the feed temperature.

[0068] The alkali feed and alkali circulation are regulated and monitored by metering pumps with flow rates of 0-1 L / h and 10-50 L / h, respectively.

[0069] S1 uses a glass plate level gauge to monitor the liquid level and manually adjusts it via an alkane-alkali discharge valve;

[0070] The circulating alkali is monitored offline using a pH meter, and the flow rate of the alkali feed pump is adjusted manually.

[0071] Sodium carbonate solution is prepared on-site using caustic soda and soft water from a waste alkali incineration unit.

[0072] All temperature, pressure, and flow rates are displayed on-site and recorded periodically.

[0073] Oxidation process: In the cyclohexane oxidation process, oxygen-containing gas is introduced into multiple reactors connected in series one after another. The gas flow rate and oxygen concentration of each reactor are adjusted, the reaction temperature is adjusted, and the residence time of cyclohexane is adjusted. The liquid phase material after the system tends to stabilize is the cyclohexane oxidation liquid.

[0074] Neutralization process: After cooling, the oxidizing liquid 01 is introduced into the upper part of the fiber membrane neutralization reactor R1. Simultaneously, an alkaline solution 15 containing sodium carbonate is introduced into the top of the fiber membrane neutralization reactor R1. The two materials flow downwards in the fiber membrane reactor R1 and separate into phases in the separation tank S1. The upper layer is the less dense cyclohexane phase 11, in which most of the cyclohexyl hydroperoxide, cyclohexanol, and cyclohexanone from the cyclohexane oxidation liquid remain, and then enters the fiber membrane decomposition reactor R2 for further reaction. The lower layer is the denser sodium carbonate aqueous phase 12, in which sodium carboxylate salts formed by the reaction of carboxylic acids and sodium carbonate in the cyclohexane oxidation liquid dissolve. The aqueous phase also contains sodium bicarbonate and unreacted sodium carbonate, along with small amounts of cyclohexyl hydroperoxide, cyclohexanol, and cyclohexanone. Most of the sodium carbonate aqueous phase 14 is mixed with the waste alkali 25 from the decomposition process and recycled to the top of the neutralization reactor R1.

[0075] A small portion of the sodium carbonate aqueous phase 13 is contacted with cyclohexane 03 in the countercurrent extraction tower C1. The poorly water-soluble organic compounds such as cyclohexyl hydroperoxide, cyclohexanol, and cyclohexanone dissolved in the sodium carbonate aqueous phase 13 are extracted into cyclohexane 17, and then mixed with the neutralized cyclohexane phase 11 before entering the fiber membrane decomposition reactor R2. The extracted sodium carbonate aqueous phase 16 is mixed with waste alkali 26 and concentrated before being sent to the incineration unit for treatment. The remaining cyclohexyl hydroperoxide is completely decomposed, and most of the cyclohexanol and cyclohexanone 27 are evaporated and returned to the neutralization process.

[0076] Decomposition Process: The cyclohexane phase 11 containing cyclohexyl hydroperoxide from the neutralization process is mixed with the alkane phase 17 from the top of extraction tower C1 and then enters the top of decomposition reactor R2. In the fiber membrane decomposition reactor R2, it is in co-current contact with the alkaline aqueous phase 23 containing sodium hydroxide, where the cyclohexyl hydroperoxide decomposes to produce cyclohexanol and cyclohexanone. Subsequently, phase separation occurs in separation tank S2. The upper cyclohexane phase 22, containing cyclohexanol and cyclohexanone, is washed with water and then enters the alkane tower for distillation separation. The lower alkaline aqueous phase containing sodium hydroxide is divided into three parts: one part 24 is mixed with fresh alkali O2 and recycled to the top of the decomposition reactor; another part 25 is mixed with the circulating sodium carbonate aqueous phase 14 from the neutralization reactor and then enters the neutralization reactor R1; and the third part 26 enters the waste alkali evaporation tower C2, where cyclohexanol and cyclohexanone are evaporated and recovered.

[0077] The fiber membrane reactor described in this embodiment of the invention is a stainless steel tube with a flange connection, an inner diameter of 50 mm, a length of 2400 mm, and is filled with metal fiber bundles with a diameter of 0.2 mm, a filling rate of 35%, and a total length of 2750 mm. The upper end is flush with the upper flange opening, and the lower end extends about 350 mm beyond the lower flange opening. The lower flange is connected to the corresponding flange opening of a separation tank with a diameter of 273 mm and a length of 1000 mm, so that the end of the fiber bundle extending beyond the lower flange opening is located exactly in the lower half of the separation tank.

[0078] Example 1

[0079] Oxidation:

[0080] In the cyclohexane oxidation process, oxygen-containing gas was introduced stage by stage into seven bubble reactors connected in series. The gas flow rate and oxygen concentration in each reactor were adjusted, and the reaction temperature was adjusted to control the oxygen content (dry basis) in the tail gas of each reactor at about 2%. The residence time of cyclohexane was adjusted to about 45 minutes. After the system stabilized, the reaction temperature was 165-170℃ and the reaction pressure was 1.2 MPa. Sampling and analysis were performed. The liquid phase material after the analysis results tended to stabilize was the cyclohexane oxidation liquid, which contained 2.82% cyclohexyl hydroperoxide, 0.88% cyclohexanol, 0.39% cyclohexanone, and 0.36% other impurities such as carboxylic acid. The calculated cyclohexane conversion rate was 3.42%, and the selectivity of useful products (including cyclohexanone, cyclohexanol, and cyclohexyl hydroperoxide) was 92.1%.

[0081] Neutralization:

[0082] The cyclohexane oxidation liquid is cooled to 60–70°C and introduced into the upper part of the fiber membrane reactor R1. Simultaneously, a pre-prepared alkali solution A containing 10% sodium carbonate is introduced into the top of the fiber membrane reactor. The volume ratio of the cyclohexane oxidation liquid to alkali solution A is 10:1. The two materials form a membrane in the fiber membrane reactor and flow downwards, separating into two phases at the bottom of the separator. The upper layer is the less dense cyclohexane phase. Most of the cyclohexyl hydrogen peroxide, cyclohexanol, and cyclohexanone in the cyclohexane oxidation liquid remain in the cyclohexane phase. The mixture then proceeds to a decomposition reactor for further reaction. This reactor contains 2.78% cyclohexyl hydroperoxide, 0.87% cyclohexanol, and 0.38% cyclohexanone; carboxylic acids are no longer detectable. The lower layer is a denser aqueous sodium carbonate phase. Sodium carboxylate salts formed by the reaction of carboxylic acids in the cyclohexane oxidation liquid with sodium carbonate dissolve in this aqueous phase. The aqueous phase also contains sodium bicarbonate and unreacted sodium carbonate. Additionally, the aqueous sodium carbonate phase contains 0.36% cyclohexyl hydroperoxide, 0.12% cyclohexanol, and 0.05% cyclohexanone.

[0083] The aqueous sodium carbonate phase is contacted with cyclohexane in a countercurrent extraction tower C1 packed with packing material. Poorly water-soluble organic compounds such as cyclohexyl hydroperoxide, cyclohexanol, and cyclohexanone dissolved in the aqueous sodium carbonate phase are extracted into the cyclohexane and then returned to the cyclohexane oxidation liquid. The total content of CHHP, cyclohexanol, and cyclohexanone in the extracted aqueous sodium carbonate phase is 0.08%. After being mixed with waste alkali and concentrated, it is sent to the incineration unit for treatment.

[0084] break down:

[0085] Oil phase A is heated to 70-80℃ and introduced into the upper part of the fiber membrane decomposition reactor R2. Simultaneously, a pre-prepared alkaline solution B containing 5% sodium hydroxide is introduced into the top of the fiber membrane reactor R2. The volume ratio of oil phase A to alkaline solution B is 10:1. The two materials flow downwards in parallel within the fiber membrane reactor, with a reaction residence time of 8-10 minutes. Cyclohexyl hydrogen peroxide decomposes to produce cyclohexanol and cyclohexanone, forming phases in the lower part of the separator. The upper layer is a less dense cyclohexane phase, with most of the cyclohexanol and cyclohexanone remaining in the cyclohexane phase. The cyclohexanol content is 1.88%, and the cyclohexanone content is 1.77%. Na... + The concentration is 1 ppm; the lower layer is a sodium hydroxide aqueous phase with a higher density. A small amount of water-soluble substances generated during the decomposition process dissolve in the aqueous phase. The total content of cyclohexanol and cyclohexanone in aqueous phase B is 0.12%.

[0086] The aqueous phase C from the extraction tower and the aqueous phase B3 from the decomposition tower are fed into the waste alkali evaporation tower together. Most of the cyclohexanol and cyclohexanone are evaporated and returned to the neutralization process. The total residual content of cyclohexanol and cyclohexanone in the bottom liquid of the waste alkali evaporation tower is 0.03%.

[0087] The neutralization and decomposition reactions each utilize a fiber membrane reactor equipped with a separation tank, resulting in a simple and clear process. Cyclohexyl hydrogen peroxide is completely converted, with a selectivity of 98% for cyclohexanol and cyclohexanone, and an alkali consumption of 75 kg NaOH / t cyclohexanone.

[0088] Example 2

[0089] Compared with Example 1, the only difference is that the neutralization reaction was carried out in a stirred tank at a temperature of 60-70°C. After neutralization, the mixture was allowed to stand in a separation tank for phase separation. The aqueous phase contained 0.48% cyclohexyl hydroperoxide, 0.16% cyclohexanol, and 0.10% cyclohexanone. The total content of CHHP, cyclohexanol, and cyclohexanone in the sodium carbonate aqueous phase after extraction was 0.12%.

[0090] The decomposition and other processes were the same as in Example 1. The cyclohexyl hydrogen peroxide was completely converted, the selectivity of cyclohexanol and cyclohexanone was 98%, and the alkali consumption was 81 kg NaOH / t cyclohexanone.

[0091] Comparative Example 1

[0092] Compared to Example 1, the only difference is that the neutralization and decomposition reactions were carried out simultaneously in three stirred tanks connected in series without an extraction tower. The decomposition temperature was 85–97°C, the total residence time was 28–30 minutes, and the decomposition products contained 1.60% cyclohexanol, 1.82% cyclohexanone, and Na. + The concentration was 5 ppm; the selectivity for cyclohexanol and cyclohexanone was 92%, and the alkali consumption was 132 kg NaOH / t cyclohexanone. The total content of cyclohexanol and cyclohexanone in the alkali solution was 0.21%. The residual total content of cyclohexanol and cyclohexanone in the bottom liquid of the waste alkali evaporator was 0.07%.

[0093] The above embodiments are illustrative of the present invention and are not intended to limit the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are only illustrative of the specific working principle of the present invention. Various changes and modifications can be made to the present invention without departing from the spirit and scope of the present invention. All such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for treating cyclohexane oxidation liquid, characterized in that: The cyclohexane oxidation solution and the alkaline solution A are neutralized to separate the oil phase A and the aqueous phase A. The oil phase A is a cyclohexane solution enriched with cyclohexyl hydrogen peroxide, cyclohexanol and cyclohexanone. The alkaline solution A is an aqueous solution containing dissolved alkali metal carbonates. Oil phase A and alkaline solution B are decomposed to separate oil phase B and aqueous phase B; oil phase B is a cyclohexane solution enriched with cyclohexanol and cyclohexanone; alkaline solution B is an aqueous solution containing alkali metal hydroxide. The neutralization and / or decomposition reactions are carried out in a fiber membrane reactor.

2. The method for treating cyclohexane oxidation liquid as described in claim 1, characterized in that: The cyclohexane oxidation solution is an oxidation reaction solution obtained by oxidizing cyclohexane.

3. The method for treating cyclohexane oxidation liquid as described in claim 2, characterized in that, The temperature during the oxidation treatment stage is 165–170℃; the pressure is 1–2 MPa.

4. The method for treating cyclohexane oxidation liquid as described in claim 2, characterized in that, In the cyclohexane oxidation solution, the content of cyclohexyl hydrogen peroxide is 1-5 v%; the content of cyclohexanol is 0.1-1.5 v%; the content of cyclohexanone is 0.1-1 v%; and the content of carboxylic acid impurities is 0.1-0.6 v%.

5. The method for treating cyclohexane oxidation liquid as described in claim 1, characterized in that, In alkaline solution A, the alkali metal carbonate is sodium carbonate, and the concentration of the solute is 1% to 30%.

6. The method for treating cyclohexane oxidation liquid as described in claim 1, characterized in that, During the neutralization reaction stage, the ratio of cyclohexane oxidation liquid to alkaline solution A is 2 to 20:

1.

7. The method for treating cyclohexane oxidation liquid as described in claim 1, characterized in that, In alkaline solution B, the alkali metal hydroxide solution is an aqueous solution of sodium hydroxide with a concentration of 1% to 10%.

8. The method for treating cyclohexane oxidation liquid as described in claim 1, characterized in that, During the decomposition reaction stage, the ratio of oil phase A to alkaline solution B is 2 to 20:

1.

9. The method for treating cyclohexane oxidation liquid as described in claim 1, characterized in that, During the neutralization reaction stage of the fiber membrane reactor, the temperature inside the reactor is controlled at 50–100℃ and the pressure is absolute at 0.1–1.0 MPa.

10. The method for treating cyclohexane oxidation liquid as described in claim 1, characterized in that, During the decomposition reaction stage of the fiber membrane reactor, the temperature inside the reactor is controlled at 70–120℃ and the pressure is absolute at 0.1–1.0 MPa.

11. The method for treating cyclohexane oxidation liquid as described in claim 1, characterized in that, The main body of the fiber membrane reactor includes a fiber membrane contactor and a separation tank. The fiber membrane contactor is composed of metal fiber filaments, which are wrapped in a cylindrical sleeve and extend out of the sleeve to the alkaline water phase at the bottom of the separation tank.

12. The method for treating cyclohexane oxidation liquid as described in claim 11, characterized in that, The cyclohexane oxidation liquid and alkali solution A enter from the top of the fiber membrane contactor. Alkali solution A flows downward in a film-like manner along the outer surface of the metal fibers, while the cyclohexane oxidation liquid flows downward in the gaps between the metal fibers. At the same time, the carboxylic acid in the cyclohexane oxidation liquid undergoes a neutralization reaction with the downward-flowing alkali solution A and is separated in the separation tank. The upper layer is the oil phase A, which then enters the decomposition reactor to continue the reaction; the lower layer is the aqueous phase A.

13. The method for treating cyclohexane oxidation liquid as described in claim 11, characterized in that: The oil phase A and the alkaline solution B enter from the top of the fiber membrane contactor. The alkaline solution B flows downward in a film-like manner along the outer surface of the metal fiber filaments, while the oil phase A flows downward in the gaps between the metal fiber filaments. At the same time, the cyclohexyl hydrogen peroxide in the oil phase A undergoes a decomposition reaction with the downward-flowing alkaline solution B and is separated in the separation tank. The upper layer is the oil phase B, which is then further washed with water and enters the alkylation tower for separation; the lower layer is the aqueous phase B.

14. The method for treating cyclohexane oxidation liquid as described in claim 1, characterized in that: The aqueous phase A is divided into two parts, A1 and A2. A1 is circulated in the reactor for the neutralization reaction, and A2 is extracted with cyclohexane through countercurrent extraction to obtain oil phase C and aqueous phase C. The oil phase C is a cyclohexane solution enriched with cyclohexyl hydrogen peroxide, cyclohexanol and cyclohexanone. After being mixed with oil phase A, it enters the reactor for the decomposition reaction. The aqueous phase C is an aqueous solution of alkali metal carbonate containing carboxylates. The aqueous phase B is divided into three parts: B1, B2, and B3. B1 is circulated in the reactor for the decomposition reaction. B2 is mixed with A1 and then circulated in the reactor for the neutralization reaction. B3 is concentrated together with the aqueous phase C in the waste alkali evaporation tower and then sent to the waste alkali incineration unit for incineration. The evaporated portion is introduced into the B2 stream.

15. The method for treating cyclohexane oxidation liquid as described in claim 14, characterized in that: The aqueous phase A is contacted with cyclohexane in a countercurrent extraction tower, and the extracted organic phase is returned to the cyclohexane oxidation liquid.

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