Preparation method and preparation device of anhydrous peroxide organic acid and method for preparing ester compound from ketone compound

Abstract

The invention relates to the field of chemical synthesis, and discloses a preparation method and a preparation device of anhydrous peroxide organic acid and a method for preparing ester compounds from ketone compounds. The preparation method comprises the following steps: respectively injecting a hydrogen peroxide solution and an organic acid mixed solution containing a catalyst into a reaction section of a reactive distillation tower for catalytic reaction; a water-carrying agent is injected into the rectifying section of the reactive rectifying tower positioned above the reaction section; carrying out gas stripping on water generated by the catalytic reaction and a downstream water-carrying agent to a rectifying section, then distilling off from the top of the reactive rectifying tower, and carrying out condensation and phase separation; and the anhydrous peroxy organic acid material is discharged from the tower bottom of the reactive distillation tower. The preparation method for preparing the anhydrous peroxy organic acid belongs to a continuous process, and the prepared material containing the anhydrous peroxy organic acid can directly enter a downstream workshop section to be directly used.

Description

Technical Field

[0001] The invention relates to the technical field of chemical synthesis, and in particular to a method and device for preparing anhydrous peroxy organic acid and a method for preparing ester compounds from ketone compounds. Background Art

[0002] Lactones are widely used chemical intermediates, such as polycaprolactone (PCL) obtained by ring-opening polymerization of ε-caprolactone, which is non-toxic, harmless, 100% biodegradable, and an important polymer material. PCL resin has good shape memory properties, low-temperature flexibility and hydrolysis resistance, and has broad application prospects in absorbable surgical sutures, facial filling materials, tissue engineering, artificial skin, medical dressings, resin bandages, fracture fixation, and dental film materials. Polycaprolactone polyols obtained by the reaction of ε-caprolactone with polyols and polycaprolactone polyurethanes obtained by reacting with diisocyanates are widely used in coatings, adhesives and other fields. In addition, ε-caprolactone can also be used as a strong solvent to dissolve many polymer resins, and has good solubility for some difficult-to-dissolve resins, such as chlorinated polyolefin resins and "ESTANE" polyurethane resins.

[0003] At present, the preparation of lactones by ketone oxidation can be divided into two methods according to the different oxidants: (1) peroxyacid oxidation method: inorganic peroxyacids and organic peroxyacids are the oxidants of the traditional Baeyer-Villiger oxidation reaction. Inorganic peroxyacids as oxidants have the advantages of simple preparation, low raw materials, simple and mild reactions, etc. However, this type of reaction has problems such as low reaction rate and yield. Organic peroxyacid oxidation method has the advantages of strong oxidizing ability, high product yield, and abundant raw material sources. It is the main production method for large-scale production of lactones (such as ε-caprolactone) in industry at home and abroad. (2) Hydrogen peroxide oxidation method: Hydrogen peroxide is used as an oxidant to oxidize ketone compounds to prepare lactones. The reaction byproduct is water, which will not pollute the environment. It meets the requirements of green chemicals and has become a research focus in recent years. However, the concentration of hydrogen peroxide is relatively low (less than 50%), and the oxidizing ability is insufficient. A catalyst needs to be added to improve the reaction activity. In addition, lactones are easily hydrolyzed. For example, ε-caprolactone is easily hydrolyzed to form 6-hydroxycaproic acid, or over-oxidized to adipic acid. Therefore, the catalyst, reaction solvent and suitable reaction conditions have a greater impact on the results. Therefore, hydrogen peroxide as an oxidant is still in the laboratory research stage. (3) Oxygen / aldehyde co-oxidation method: The oxidation of ketone compounds with oxygen as an oxidant usually requires the assistance of a catalyst, and aldehydes are used as co-oxidants. The reaction conditions are mild and the reaction efficiency is high. However, the amount of co-oxidant used is more than twice the molar amount of the ketone compound, and the by-product acid production makes it difficult to purify the product. (4) Bio-oxidation method: A method of using biological enzymes or microbial fermentation to oxidize ketone compounds to prepare lactones (such as cyclohexanone to synthesize ε-caprolactone). Although biocatalysts are environmentally friendly, efficient and specific, enzymes and microorganisms are expensive, have poor stability, and require high energy consumption for product purification. Therefore, the bio-oxidation method is still in the experimental research stage and is still far from large-scale industrial production.

[0004] At present, the domestic and foreign industries usually adopt a two-step method to synthesize lactones, that is, first synthesizing anhydrous peroxy organic acid, and then oxidizing ketone compounds with anhydrous peroxy organic acid to generate lactone. The main differences lie in the preparation process of anhydrous peroxy acid, the type of peroxy acid and the oxidation process.

[0005] CN1035379C synthesizes ε-caprolactone in two steps. In a 2L reactor, boric acid is used as a catalyst, ethyl propionate is used as a water-carrying agent, and lutidine is used as a stabilizer. Propionic acid is oxidized into peroxypropionic acid using 30-70% hydrogen peroxide. The reaction is carried out for 2.5-4 hours under a negative pressure of 10-300 mmHg and a reaction temperature of 30-100°C to generate a 10-30% peroxypropionic acid solution. Then, in a 1L intermittent reactor, cyclohexanone is added dropwise to the heated peroxypropionic acid solution. The molar ratio of peroxypropionic acid to cyclohexanone is about 1.2. The reaction temperature is controlled at 50°C and the reaction is carried out for 3 hours. The cyclohexanone conversion rate and ε-caprolactone selectivity are greater than 97% and 99%, respectively. This method adopts an intermittent operation process, which is troublesome to operate. Moreover, the concentration of the intermediate product peroxypropionic acid is too high (23%), which may easily cause safety accidents during storage and heating. Since cyclohexanone is added dropwise to the peroxypropionic acid heated to a certain temperature, the peroxypropionic acid may decompose. In addition, the residual amount of peroxypropionic acid in this method is greater than 3.5%, which greatly reduces the utilization rate of the peroxypropionic acid.

[0006] CN103539770B discloses a continuous reaction process for preparing ε-caprolactone. In a microchannel reactor, peracetic acid is first synthesized by reacting hydrogen peroxide with acetic anhydride, and then cyclohexanone is oxidized to continuously synthesize ε-caprolactone. When the molar ratio of peracetic acid to cyclohexanone is 1.5, the cyclohexanone conversion rate can be greater than 90% and the ε-caprolactone selectivity can be greater than 98% when the reaction temperature is greater than 70°C and the residence time is 500s. Compared with the traditional intermittent reaction process, the reaction efficiency and safety of this method are improved, but the utilization rate of peroxyacid is poor, and since the water brought by the raw material hydrogen peroxide is not separated, the ε-caprolactone will be hydrolyzed to generate 6-hydroxycaproic acid during the reaction.

[0007] CN103570667B discloses a method for continuously preparing ε-caprolactone, wherein a peroxycarboxylic acid solution and cyclohexanone are added to the first stirred tank of 2 to 8 stirred tanks connected in series, and then the reaction materials overflow from each tank until the last tank obtains a solution containing ε-caprolactone, wherein the molar ratio of the peroxycarboxylic acid to the cyclohexanone is 1 to 1.2, and when the temperature is 30 to 70°C and the total residence time of the reaction materials is 3 to 7 hours, the cyclohexanone conversion rate can reach 99%, and the ε-caprolactone selectivity can reach 98%. However, the process has high energy consumption, long reaction time, and serious back-mixing of the reaction materials, which greatly reduces the reaction selectivity.

[0008] CN105646433A introduces a process for continuously preparing ε-caprolactone, which uses a reaction and separation integrated continuous device consisting of a catalytic reaction distillation tower (synthesizing anhydrous peroxyacid), a reaction distillation tower (removing moisture from raw material cyclohexanone), a stirred reactor (synthesizing ε-caprolactone) and a distillation tower (separation). Although this method avoids the hydrolysis of ε-caprolactone, it has high energy consumption and complicated operation.

[0009] CN111763192A discloses a method and device for continuously producing ε-caprolactone, wherein hydrogen peroxide, a water-carrying agent and a stabilizer are mixed and then dehydrated, and then mixed with an organic acid after dehydration, and then enter a tubular reactor equipped with a molecular sieve catalyst, and the reaction product is dehydrated for a second time to obtain anhydrous peroxy organic acid, and then the anhydrous peroxy organic acid is mixed with cyclohexanone and enters a second tubular reactor equipped with a catalyst to react to generate a crude ester, and then distilled to obtain ε-caprolactone. Although this method can continuously produce ε-caprolactone, it is not easy to control the temperature using a tubular fixed bed reactor, and it is more troublesome to load the catalyst. Summary of the invention

[0010] The purpose of the present invention is to overcome the problem that the prior art has low concentration when preparing peroxy organic acid, and that the peroxy organic acid is used as a raw material intermediate to prepare downstream inferior products, such as the problem that lactone cannot be stored for a long time for standby use, and to provide a method for preparing anhydrous peroxy organic acid and a preparation device, as well as a method for preparing ester compounds from ketone compounds. The preparation method can not only achieve the preparation of peroxy organic acid with a relatively high concentration, but also has good safety. The anhydrous peroxy organic acid material prepared by the preparation method is used as an upstream raw material intermediate to prepare downstream products, which solves the safety problem of storage and transportation of the intermediate product peroxy acid under high concentration conditions. The intermediate product peroxy acid does not need to be stored and transported, and directly enters a process. For example, using it in the preparation of ester compounds from ketone compounds can increase the conversion rate of ketone compounds and the selectivity of ester compounds, and reduce the subsequent separation costs.

[0011] In order to achieve the above-mentioned object, the first aspect of the present invention provides a method for preparing anhydrous peroxy organic acid, which comprises: injecting a hydrogen peroxide solution and a catalyst-containing organic acid mixture into a reaction section of a reaction distillation tower for catalytic reaction; injecting a water-carrying agent into a distillation section of the reaction distillation tower located above the reaction section; water generated by the catalytic reaction and the downward water-carrying agent are gas-lifted to the distillation section, and then distilled from the top of the reaction distillation tower, condensed and phase-separated; and discharging anhydrous peroxy organic acid material from the bottom of the reaction distillation tower.

[0012] The second aspect of the present invention provides a preparation device for anhydrous peroxy organic acid, which comprises: a reaction distillation tower; the reaction distillation tower is provided with a hydrogen peroxide solution feed port, a catalyst-containing organic acid mixed liquid feed port and a water-carrying agent feed port; the reaction distillation tower comprises a reaction section and a distillation section located above the distillation section, and the water-carrying agent feed port is arranged in the distillation section; the reaction section and the distillation section are bounded by the hydrogen peroxide solution feed port and the organic acid mixed liquid feed port containing a homogeneous catalyst; a gas outlet is provided at the top of the reaction distillation tower, and the gas outlet is connected to a condenser and a water separator in sequence, so as to separate the distillate from the top of the tower into phases in the water separator after condensation.

[0013] A third aspect of the present invention provides a method for preparing an ester compound from a ketone compound, the method comprising:

[0014] S1 prepares an anhydrous peroxy organic acid material according to the preparation method of the first aspect of the present invention;

[0015] The S2 ketone compound and the anhydrous peroxy organic acid material are respectively introduced into the microscale reaction unit for Baeyer-Villiger oxidation reaction.

[0016] Compared with the prior art, the present invention has at least the following beneficial effects:

[0017] (1) Peracids are easy to decompose and explode, so they cannot be stored for a long time. However, the existing production process cannot solve this problem. They can only be produced and stored for backup, and there are also quantity requirements. From the perspective of safe production, the concentration of peracid stored cannot be higher than 18%, and the storage volume cannot exceed 20m3 at a time. 3 , otherwise it is easy to explode; the preparation method of the present invention is a continuous process for preparing anhydrous peroxy organic acid, and the prepared material containing anhydrous peroxy organic acid can be directly used in the downstream process section.

[0018] (2) The inventors have found that the water content of the peroxyacid solution synthesized by an intermittent stirred tank is generally 25-30%; the water content of the material containing anhydrous peroxy organic acid prepared by the preparation method of the present invention is about 21%, which can reduce the subsequent separation cost;

[0019] (3) When anhydrous peroxy organic acid is prepared by an intermittent stirred tank at the same temperature and pressure, the concentration of peroxy propionic acid generated is about 16%, while the content of anhydrous peroxy organic acid in the anhydrous peroxy organic acid material stream prepared by the preparation method of the present invention is greater than about 20%;

[0020] (4) The preparation method of the anhydrous peroxy organic acid of the present invention is used as the upstream process of preparing lactone from ketone compounds, which solves the safety problem of storage and transportation of the intermediate product peroxy organic acid under high concentration conditions. The intermediate product peroxy organic acid does not need to be stored and transported, and directly enters the next process of preparing ester compounds from ketone compounds. The prepared anhydrous peroxy organic acid material has a lower water content, which accelerates the reaction process and inhibits the hydrolysis of the subsequent synthesized ester compounds. The downstream process of preparing ester compounds from ketone compounds adopts microscale chemical technology, which is inherently safe and can achieve rapid mixing and rapid heat exchange as well as uniform reaction time, so that the exothermic reaction of peroxy organic acid oxidizing ketone compounds to synthesize lactone can achieve precise temperature control, thereby improving the selectivity of ester compounds. The two-stage overall process is combined with the reaction time under the same indicator conditions as the prior art, which is greatly shortened and the safety is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a schematic flow chart of a method for preparing lactone from ketone compounds in one embodiment of the present invention.

[0022] Description of Reference Numerals

[0023] 1. Water-containing agent 2. Organic acid mixture containing catalyst

[0024] 3. Hydrogen peroxide solution 4 / 5 / 6 / 19 / 20 / 21, metering pump

[0025] 7. Reaction distillation tower 8. Condenser

[0026] 9. Reflux pump 10. Water distributor

[0027] 11. Vacuum pump 12. Wastewater treatment unit

[0028] 13. Tower kettle reboiler 14. Circulation pump

[0029] 15. Valve 16. Ketone compounds

[0030] 17 / 18, Filter 22, Microscale Reactor

[0031] 23. Separation unit 24. Distillation section

[0032] 25. Liquid phase distributor 26. Reaction section DETAILED DESCRIPTION

[0033] The endpoints and any values ​​of the ranges disclosed in this article 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 each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0034] The first aspect of the present invention provides a method for preparing anhydrous peroxy organic acid, which comprises: injecting a hydrogen peroxide solution and a catalyst-containing organic acid mixed liquid into a reaction section of a reaction distillation tower for catalytic reaction; injecting a water-carrying agent into a distillation section of the reaction distillation tower located above the reaction section; water generated by the catalytic reaction and the downwardly flowing water-carrying agent are gas-lifted to the distillation section, and then distilled from the top of the reaction distillation tower, condensed, and phase-separated; and discharging anhydrous peroxy organic acid material from the bottom of the reaction distillation tower.

[0035] In the present invention, a high-concentration anhydrous peroxy organic acid material can be prepared through a continuous process, which reduces the separation cost, and the prepared anhydrous peroxy organic acid material can be directly supplied to the downstream process section for use, solving the safety problem of storage and transportation of the intermediate product peroxy acid under high concentration conditions. When the peroxy acid is used as an intermediate product, it does not need to be stored and transported, and directly enters a process.

[0036] In the present invention, the organic acid mixed liquid containing a catalyst refers to a mixed material obtained by mixing a catalyst and an organic acid.

[0037] According to the present invention, in some embodiments, the hydrogen peroxide solution and the organic acid mixture containing the catalyst are distributed by a liquid phase distributor located between the reaction section and the rectification section and then flow into the reaction section for catalytic reaction. By adopting the above embodiment, a high concentration of anhydrous peroxy organic acid material can be obtained.

[0038] According to the present invention, in some embodiments, the water-carrying agent is injected into the rectifying section from the upper part, the middle part or the lower part of the rectifying section, preferably from the middle part of the rectifying section. The oxidation of hydrogen peroxide to synthesize peroxy acid is a balance control and exothermic reaction, and the water generated by the reaction needs to be continuously removed to accelerate the reaction process. The inventors have found that by adopting the aforementioned embodiment, the water-carrying agent can better carry out the water generated by the catalytic reaction and the water brought in by the raw materials, and the generated water is continuously removed. The heat released by the hydrogen peroxide oxidation reaction can also be removed through liquid water to maintain the thermal stability of the reaction distillation tower.

[0039] According to the present invention, it can be understood that the overhead distillate contains water and a water-carrying agent, and may also contain an organic acid. After phase separation, an upper organic phase containing a water-carrying agent and an organic acid and a lower aqueous phase can be obtained. According to the present invention, in some embodiments, the organic phase obtained by phase separation is refluxed into the reaction distillation tower and continues to descend to the reaction section to participate in the catalytic reaction. The aforementioned embodiment can not only realize the recycling of raw materials, but also further increase the concentration of anhydrous peroxy organic acid in the anhydrous peroxy organic acid material.

[0040] According to the present invention, in some preferred embodiments, the organic phase obtained by phase separation is refluxed from the top of the rectification section into the reactive distillation tower. The above preferred embodiments can increase the concentration of the anhydrous peroxy organic acid in the anhydrous peroxy organic acid material.

[0041] According to the present invention, in some preferred embodiments, the reflux ratio of the organic phase is 1-3, for example, 1, 1.5, 2, 2.5, 3, or a range consisting of any two of the above values, preferably 1-2.5. By adopting the above preferred embodiments, the concentration of anhydrous peroxy organic acid in the anhydrous peroxy organic acid material can be increased.

[0042] In the present invention, the reflux ratio refers to the mass flow ratio of the organic phase refluxed into the reactive distillation tower to the distillate from the top of the distillation tower.

[0043] According to the present invention, in some embodiments, the lower aqueous phase obtained by phase separation is discharged, and the discharged lower aqueous phase can enter a wastewater treatment unit for treatment.

[0044] According to the present invention, in some embodiments, the discharged anhydrous peroxy organic acid material is divided into two paths of materials, one path of materials enters the downstream process section, and the other path of materials returns to the reaction section after heating. The aforementioned preferred embodiment can provide the temperature required by the reaction section, and at the same time increase the concentration of anhydrous peroxy organic acid in the anhydrous peroxy organic acid material, thereby reducing the subsequent separation cost.

[0045] According to the present invention, in some preferred embodiments, the other material is returned to the reaction section after being heated. By adopting the above preferred embodiments, the concentration of anhydrous peroxy organic acid in the anhydrous peroxy organic acid material can be increased, the subsequent separation cost can be reduced, and the safety problem of storage and transportation of the intermediate product peroxy acid under high concentration conditions can be effectively solved.

[0046] According to the present invention, in some preferred embodiments, another path of materials is heated and returned to the reaction section from the bottom of the reactive distillation tower.

[0047] According to the present invention, in some preferred embodiments, the heating temperature is 70-90°C, for example, 70°C, 75°C, 80°C, 90°C, or a range consisting of any two of the above values. The above preferred embodiments can make the separation of light and heavy components in the system more thorough, reduce the content of water-carrying agent in the anhydrous peroxy organic acid material discharged from the bottom of the reaction distillation tower, and thus reduce the subsequent separation cost.

[0048] According to the present invention, as long as the purpose of the present invention can be achieved, the source of the hydrogen peroxide solution is not particularly limited and can be obtained commercially. In some embodiments, the hydrogen peroxide solution is a hydrogen peroxide aqueous solution with a mass fraction of 30-80%.

[0049] According to the present invention, as long as the purpose of the present invention can be achieved, the type of the organic acid is not particularly limited. In some embodiments, the organic acid is selected from C1-C6 organic acids, preferably selected from one or more of acetic acid, propionic acid and butyric acid. It can be understood by those skilled in the art that when the organic acid is acetic acid, the prepared anhydrous peroxy organic acid is anhydrous peracetic acid; when the organic acid is propionic acid, the prepared anhydrous peroxy organic acid is anhydrous peroxy propionic acid; when the organic acid is butyric acid, the prepared anhydrous peroxy organic acid is anhydrous peroxy butyric acid. In the present invention, the type of organic acid can be selected according to actual needs. In the present invention, propionic acid is used as an organic acid to prepare anhydrous peroxy propionic acid as an example to illustrate the advantages of the present invention, but the present invention is not limited to this.

[0050] According to the present invention, as long as the purpose of the present invention can be achieved, the type of the catalyst is not particularly limited. In order to facilitate the reaction, the catalyst includes a homogeneous catalyst.

[0051] According to the present invention, in some preferred embodiments, the homogeneous catalyst is selected from one or more of phosphoric acid, sulfuric acid, boric acid, methanesulfonic acid and p-toluenesulfonic acid, preferably sulfuric acid and / or boric acid.

[0052] According to the present invention, as long as the purpose of the present invention can be achieved, the type of the water-carrying agent is not particularly limited. In some embodiments, the water-carrying agent is selected from compounds that can form an azeotropic agent with water.

[0053] According to the present invention, in some preferred embodiments, the water-carrying agent is at least one of low-level esters, chloroalkanes and cyclic hydrocarbons, wherein low-level esters refer to ester compounds with carbon atoms between 2 and 8, such as ethyl acetate and ethyl propionate; chloroalkanes are preferably chlorinated C1-C3 alkanes; cyclic hydrocarbons are preferably cycloalkanes, and further preferably C6-C10 cycloalkanes. Preferably, the water-carrying agent is selected from one or more of ethyl acetate, ethyl propionate, chloroform and cyclohexane.

[0054] According to the present invention, as long as the purpose of the present invention can be achieved, the amount of the catalyst is not particularly limited. In some embodiments, the amount of the catalyst is 0.1-2wt% of the mass of the hydrogen peroxide solution, such as 0.1wt%, 0.3wt%, 0.5wt%, 0.7wt%, 0.1wt%, 1.2wt%, 1.5wt%, 1.8wt%, 2wt%, or a range consisting of any two of the above values.

[0055] According to the present invention, as long as the purpose of the present invention can be achieved, the amount of the water-carrying agent is not particularly limited. In some embodiments, the molar ratio of the water-carrying agent to hydrogen peroxide is 1-4: 1, for example, 1: 1, 1.5: 1, 2: 1, 2.5: 1, 3: 1, 3.5: 1, 4: 1, or a range composed of any of the above numerical values, preferably 1.5-3: 1. The above embodiment can make the separation of light and heavy components in the system more thorough, reduce the content of the water-carrying agent in the anhydrous peroxy organic acid material discharged from the bottom of the reactive distillation tower, and thus reduce the subsequent separation cost.

[0056] According to the present invention, as long as the purpose of the present invention can be achieved, the amount of the organic acid is not particularly limited. In some embodiments, the molar ratio of the organic acid to hydrogen peroxide is 1-6: 1, for example, 1: 1, 2: 1, 3: 1, 4: 1, 5: 1, 6: 1, or a range consisting of any of the above values, preferably 3-5: 1. By adopting the above embodiment, the relative content of the anhydrous peroxy organic acid in the anhydrous peroxy organic acid material can be further increased, thereby reducing the subsequent separation cost.

[0057] According to the present invention, in some embodiments, the reactive distillation tower is operated under negative pressure. The above-mentioned embodiment can better promote the occurrence of catalytic reaction to prepare anhydrous peroxy organic acid, and at the same time, it can make the separation of light and heavy components more thorough, reducing the subsequent separation cost.

[0058] According to the present invention, in some preferred embodiments, the operating pressure of the reactive distillation tower is 10-500 mbar (gauge pressure), such as 10 mbar, 30 mbar, 50 mbar, 80 mbar, 100 mbar, 130 mbar, 150 mbar, 200 mbar, 300 mbar, 400 mbar or 500 mbar. The above embodiment can better promote the occurrence of catalytic reaction to prepare anhydrous peroxy organic acid, and at the same time make the separation of light and heavy components more thorough, thereby reducing the subsequent separation cost.

[0059] According to the present invention, in some embodiments, the temperature of the reaction section is 40-80° C., such as 40° C., 50° C., 60° C., 65° C., 70° C. or 80° C. The above-mentioned embodiments can better promote the occurrence of catalytic reaction to prepare anhydrous peroxy organic acid, and at the same time, make the separation of light and heavy components more thorough, thereby reducing the subsequent separation cost.

[0060] According to the present invention, as long as the purpose of the present invention can be achieved, the condensation conditions are not particularly limited. In order to enable the organic phase and the aqueous phase to be better separated, in some embodiments, the condensation conditions include: the condensation temperature is 5-20°C, for example, 5°C, 8°C, 10°C, 15°C or 20°C.

[0061] According to the present invention, in some embodiments, the distillation section is a plate tower, a packed tower or a composite tower, preferably a plate tower. The above preferred embodiments can achieve a wider process operation range and more convenient device operation.

[0062] According to the present invention, as long as the purpose of the present invention can be achieved, the number of theoretical plates of the plate tower is not particularly limited. In some preferred embodiments, the number of theoretical plates of the plate tower is 4-8, for example, 4, 5, 6, 7, 8, or a range consisting of any two of the above values.

[0063] According to the present invention, in some embodiments, the reaction section is a packed tower. The above preferred embodiments can enhance the reaction rate and avoid the decomposition of the generated anhydrous peroxy organic acid.

[0064] According to the present invention, in some preferred embodiments, the packing in the packed tower is in the form of structured packing and / or random packing; wherein, structured packing is a packing that is uniformly arranged and neatly stacked in a geometric pattern in the tower, and random packing is a monomer with a certain geometric shape and size, generally randomly stacked in the tower, and there is no special limitation on this in the present invention.

[0065] According to the present invention, in some preferred embodiments, the material of the filler in the packed tower is at least one of metal, ceramic, polytetrafluoroethylene, glass fiber and carbon fiber; the above materials can be specially treated by any method in the art.

[0066] In the present invention, the geometric shape and size of the filler monomer can be selected as needed. Specifically, the filler monomer in the present invention can be selected as glass fiber spring, metal perforated plate corrugation, metal perforated plate corrugation, etc.

[0067] The second aspect of the present invention provides a preparation device for anhydrous peroxy organic acid, which comprises: a reaction distillation tower; the reaction distillation tower is provided with a hydrogen peroxide solution feed port, a catalyst-containing organic acid mixed liquid feed port and a water-carrying agent feed port; the reaction distillation tower comprises a reaction section and a distillation section located above the distillation section, and the water-carrying agent feed port is arranged in the distillation section; the reaction section and the distillation section are bounded by the hydrogen peroxide solution feed port and the organic acid mixed liquid feed port containing a homogeneous catalyst; a gas outlet is provided at the top of the reaction distillation tower, and the gas outlet is connected to a condenser and a water separator in sequence, so as to separate the distillate from the top of the tower into phases in the water separator after condensation.

[0068] The existing equipment for preparing anhydrous peroxy organic acid generally adopts intermittent stirring kettle. However, since anhydrous peroxy organic acid is easy to decompose and explode, it cannot be stored for a long time. However, the existing production equipment cannot solve this problem. It can only be produced and reserved first, and there are also quantity requirements. From the perspective of safe production, the concentration of the reserved peroxy acid cannot be higher than 18%, and the reserve volume cannot exceed 20m3 at a time. 3 Otherwise, it is easy to explode. By adopting the preparation device of the present invention, anhydrous peroxy organic acid can be continuously prepared. The preparation device is used in conjunction with other continuous process devices. There is no storage of explosive intermediate products, and high-concentration anhydrous peroxy organic acid materials can be prepared.

[0069] According to the preparation device of the present invention, in some embodiments, the reaction distillation tower further comprises a liquid phase distributor located between the reaction section and the distillation section, which is used to distribute the hydrogen peroxide solution and the organic acid mixed liquid containing the catalyst and then flow into the reaction section for catalytic reaction. By adopting the above embodiment, a high concentration of anhydrous peroxy organic acid material can be obtained.

[0070] In the present invention, it can be understood that the liquid phase distributor is the boundary between the distillation section and the reaction section in the reaction distillation tower, wherein the heights of the distillation section and the reaction section are not particularly limited and may be the same or different. Preferably, the height of the reaction section is higher than or equal to the height of the distillation section. In the embodiments of the present invention, the height of the reaction section is equal to the height of the distillation section (i.e., the liquid phase distributor is located in the middle of the reaction distillation tower) as an example to illustrate the advantages of the present invention, but the present invention is not limited to this.

[0071] According to the preparation device of the present invention, in some preferred embodiments, the water-containing agent feed port is located at the upper part, middle part or lower part of the rectification section, preferably the middle part. By adopting the above embodiment, a high-concentration anhydrous peroxy organic acid material can be obtained.

[0072] According to the preparation device of the present invention, in some embodiments, the upper part of the water separator is connected to the distillation section through a reflux pump.

[0073] According to the preparation device of the present invention, in order to better treat the water phase in the water separator, in some embodiments, the bottom of the water separator is connected to an external wastewater treatment unit.

[0074] According to the preparation device of the present invention, the prepared anhydrous peroxy organic acid material is located at the bottom of the reaction distillation tower. In order to enable the prepared anhydrous peroxy organic acid material to be supplied to other devices as a raw material intermediate for the next step, in some embodiments, a bottom liquid phase outlet is provided at the bottom of the reaction distillation tower.

[0075] According to the preparation device of the present invention, in some embodiments, the bottom liquid phase outlet is connected to a circulation pump, and the outlet pipeline of the circulation pump is divided into two paths, one of which is connected to the downstream section, and the other is connected to the bottom of the tower reboiler and the reactive distillation tower in sequence. By adopting the above-mentioned embodiment, not only can the prepared anhydrous peroxy organic acid material be supplied according to the needs of the downstream device, but also the catalytic reaction can be better promoted to prepare the anhydrous peroxy organic acid, and at the same time, the light and heavy components can be separated more thoroughly, reducing the subsequent separation cost.

[0076] According to the preparation device described in the present invention, a metering pump can be arranged at the front end of each feed port according to the feeding needs. For example, a corresponding metering pump is arranged at the front end of the hydrogen peroxide solution feed port, the catalyst-containing organic acid mixture and the water-containing agent feed port, and connecting pipelines are arranged between various devices as needed, which will not be elaborated here.

[0077] According to the preparation device of the present invention, in order to enable the reaction distillation tower to achieve negative pressure operation, in some embodiments, a vacuum pump is further connected downstream of the water separator.

[0078] A third aspect of the present invention provides a method for preparing an ester compound from a ketone compound, the method comprising:

[0079] S1 prepares an anhydrous peroxy organic acid material according to the preparation method of the first aspect of the present invention;

[0080] The S2 ketone compound and the anhydrous peroxy organic acid material are respectively introduced into the microscale reaction unit for Baeyer-Villiger oxidation reaction.

[0081] In the present invention, the preparation method of the anhydrous peroxy organic acid material prepared in step S1 is a continuous process, and the Baeyer-Villiger oxidation reaction in step S2 is also a continuous reaction. There is no storage of explosive intermediate products, and the use of the preparation method of the first aspect of the present invention to prepare the anhydrous peroxy organic acid material can accelerate the reaction process while inhibiting the subsequent hydrolysis of the synthesized lactone, thereby improving the lactone selectivity. The full-process continuous production technology for preparing lactone using the method of the present invention is conducive to device scale-up.

[0082] According to the present invention, in some embodiments, the ketone compound is fed in one time. By adopting the above embodiment, the conversion rate of the ketone compound can be further improved.

[0083] According to the present invention, in some embodiments, the anhydrous peroxy organic acid material is fed all at once or in stages; wherein, the one-time feeding refers to that the anhydrous peroxy organic acid material enters the inlet of the microscale reaction unit all at once, and the staged feeding refers to that the anhydrous peroxy organic acid material is divided into multiple strands, the first strand enters from the inlet of the microscale reaction unit, and the remaining anhydrous peroxy organic acid materials enter from any position of the microscale reaction unit along the material flow direction, such as the middle position of the microscale reaction unit, or other positions.

[0084] According to the present invention, in some preferred embodiments, the anhydrous peroxy organic acid material is fed in stages. By adopting the above-mentioned embodiment, the decomposition of the high-concentration anhydrous peroxy organic acid can be avoided; wherein, when the anhydrous peroxy organic acid material is fed in stages, the specific number of the anhydrous peroxy organic acid material segments is not particularly limited, for example, it is divided into 2 stages, 3 stages, or 4 stages.

[0085] According to the present invention, when feeding in stages, the feed amount of the anhydrous peroxy organic acid material in each stage may be the same or different, and the feed amount of the anhydrous peroxy organic acid material in the previous stage is greater than or equal to the feed amount of the anhydrous peroxy organic acid material in the adjacent subsequent stage. It is further preferred that the volume ratio of the feed amount of the anhydrous peroxy organic acid material in the previous stage to the feed amount of the anhydrous peroxy organic acid material in the adjacent subsequent stage is (1-2):1, for example, 1; 1, 1.1; 1, 1.2; 1, 1.5; 1, 1.8; 1, 2; 1, or a range consisting of any two of the above ratios, preferably (1.1-1.5):1.

[0086] According to the present invention, microscale chemical technology is inherently safe, can achieve rapid mixing and rapid heat exchange as well as uniform reaction time, so that the exothermic reaction of peroxyacid oxidation of ketone compounds to synthesize lactone can be precisely temperature controlled, thereby improving the selectivity of ester compounds. As long as the purpose of the present invention can be achieved, the number of the microscale reactors is not limited. In some embodiments, the microscale reaction unit is a single-stage or multi-stage microscale reactor connected in series.

[0087] According to the present invention, in some preferred embodiments, the equivalent diameter of the micro-scale reactor is 100-2000 μm, for example, 100 μm, 200 μm, 500 μm, 800 μm, 1000 μm, 1200 μm, 1500 μm or 2000 μm, and a range consisting of any of the above values, preferably 200-1600 μm.

[0088] According to the present invention, in some preferred embodiments, the anhydrous peroxy organic acid material is filtered and then enters the microscale reaction unit.

[0089] In the present invention, the filtration can be carried out by conventional methods in the art, for example, a filter can be installed at the rear end of a circulation pump in the anhydrous peroxy organic acid preparation device as required. The anhydrous peroxy organic acid material is filtered by the filter before entering the microscale reactor, which can prevent the microscale reaction unit from being blocked and reduce the maintenance and shutdown rate of the device.

[0090] According to the present invention, as long as the purpose of the present invention can be achieved, the amount of ketone compounds and anhydrous peroxy organic acid materials is not particularly limited. In some embodiments, the molar ratio of anhydrous peroxy organic acid to ketone compounds in the anhydrous peroxy organic acid material is 1-2: 1, for example, 1: 1, 1.1: 1, 1.2: 1, 1.4: 1, 1.5: 1, 1.8: 1 or 2: 1. The above-mentioned embodiment can better increase the conversion rate of ketone compounds and the selectivity of lactone.

[0091] According to the present invention, those skilled in the art can select the corresponding ketone compound according to the desired ester product. In some embodiments, the ketone compound is selected from at least one of cyclohexanone, cyclopentanone, acetophenone and cyclohexyl ketone, preferably cyclohexanone.

[0092] According to the present invention, in some embodiments, the reaction conditions of the Baeyer-Villiger oxidation reaction include: the reaction temperature is 40-100°C.

[0093] According to the present invention, in some embodiments, the reaction pressure is normal pressure-1.5 MPa.

[0094] According to the present invention, in some preferred embodiments, it is preferably 1-1.5 MPa, such as 1 MPa, 1.2 MPa or 1.5 MPa. The above embodiment can ensure that the reaction system is always a liquid-liquid reaction system, avoiding the decomposition of the anhydrous peroxy organic acid.

[0095] According to the present invention, in some embodiments, the reaction conditions of the Baeyer-Villiger oxidation reaction include: a reaction residence time of 10-60 min.

[0096] The following is combined with Figure 1 , the process of the method for preparing ester compounds from ketone compounds of the present invention is described in detail.

[0097] According to the present invention, in some embodiments, a hydrogen peroxide solution 3, a catalyst and an organic acid are mixed to obtain a catalyst-containing organic acid mixed solution 2, which is metered by a metering pump 6 and a metering pump 5 respectively and then enters a reaction distillation tower 7. After being evenly distributed by a liquid phase distributor 25 located in the middle of the reaction distillation tower 7, the liquid phase flows into a reaction section 26 of the reaction distillation tower 7 to undergo a catalytic reaction to generate peroxy organic acid and water.

[0098] The water-carrying agent 1 is metered by the metering pump 4 and enters from the middle of the distillation section 24 of the reaction distillation tower 7. In the reaction distillation tower, the water generated in the reaction section 26 contacts with the water-carrying agent descending from the distillation section 24 and is heated by the tower kettle reboiler 13 and then extracted with the gas. The gas phase rising from the reaction section 26 enters the distillation section. In the distillation section 24, the mixture containing the water-carrying agent-water is distilled from the top of the tower, condensed by the condenser 8 and enters the water separator 10. The upper organic phase in the water separator 10 is refluxed from the top of the distillation section 24 to the reaction distillation tower 7 through the reflux pump 9, and continues to descend to the reaction section of the reaction distillation tower 7. The lower water phase enters the wastewater treatment unit 12.

[0099] After the anhydrous peroxy organic acid material discharged from the bottom of the reaction distillation tower 7 passes through the circulation pump 14, a part of it is divided into two streams of anhydrous peroxy organic acid materials. One stream of the anhydrous peroxy organic acid material is filtered through the filter 17 and metered by the metering pump 20 and enters the microscale reactor 22 together with the raw ketone compound 16 metered by the metering pump 19 for Baeyer-Villiger oxidation reaction. The other stream of the anhydrous peroxy organic acid material is filtered through the valve 15 and the filter 18 and metered by the metering pump 21 and introduced from the rear section of the microscale reactor 22 for Baeyer-Villiger oxidation reaction, and the reaction product enters the subsequent separation unit 23 for separation; the other part of the anhydrous peroxy organic acid material discharged from the bottom of the reaction distillation tower 7 after passing through the circulation pump 14 passes through the tower bottom reboiler 13 and returns to the reaction section 26 from the bottom of the reaction distillation tower.

[0100] The present invention will be described in detail below through examples.

[0101] Example 1

[0102] A 50% by mass hydrogen peroxide solution 3, a catalyst (98% by mass concentrated sulfuric acid) and an organic acid (propionic acid) are mixed to obtain a catalyst-containing organic acid mixed solution 2, which enters a reaction distillation tower 7 after being metered by a metering pump 6 and a metering pump 5, and after being evenly distributed by a liquid phase distributor 25 located in the middle of the reaction distillation tower 7, the liquid phase flows into a reaction section 26 (a packed tower, in which the packing in the packed tower is a random packing of glass fiber springs) of the reaction distillation tower 7 to undergo a catalytic reaction to generate peroxy organic acid and water; wherein the amount of the catalyst used is 1% of the mass of the feed of the 50% by mass hydrogen peroxide solution 3;

[0103] The water-carrying agent 1 (ethyl propionate) is metered by the metering pump 4 and enters from the middle of the distillation section 24 (a plate tower with a theoretical number of 5 plates) of the reaction distillation tower 7. In the reaction distillation tower, the water generated in the reaction section 26 contacts with the water-carrying agent descending from the distillation section 24 and is heated by the tower bottom reboiler 13 and then withdrawn with the gas. The gas phase rising from the reaction section 26 enters the distillation section. In the distillation section 24, the mixture containing the water-carrying agent and water is distilled from the top of the tower, condensed by the condenser 8, and enters the water separator 10. The upper organic phase in the water separator 10 is refluxed from the top of the distillation section 24 by the reflux pump 9. Flow into the reaction distillation tower 7, continue to descend to the reaction section of the reaction distillation tower 7, and the lower aqueous phase enters the wastewater treatment unit 12; wherein, the molar ratio of ethyl propionate to hydrogen peroxide in the hydrogen peroxide solution 3 is 1.5:1, the molar ratio of propionic acid to hydrogen peroxide in the hydrogen peroxide solution 3 is 4:1, the reflux ratio of the upper organic phase is 2, and the operating pressure of the reaction distillation tower 7 is controlled to be 100 mbar (gauge pressure) by a vacuum pump connected to the water separator 10, the temperature of the reaction section 26 is 65°C, and the condensation temperature is 10°C; the temperature of the tower kettle reboiler 13 is 80°C;

[0104] The anhydrous peroxypropionic acid material discharged from the bottom of the reaction distillation tower 7 passes through the circulation pump 14, and then partially passes through the filter 17 and is metered by the metering pump 20, and then enters the microscale reactor 22 with an equivalent diameter of 1000 μm for Baeyer-Villiger oxidation reaction together with the raw ketone compound 16 (cyclohexanone) metered by the metering pump 19, and the reaction product enters the subsequent separation unit 23 for separation; wherein, the conditions of the Baeyer-Villiger oxidation reaction are: the molar ratio of anhydrous peroxypropionic acid to cyclohexanone in the anhydrous peroxypropionic acid material is 1.1:1, the reaction temperature is 90° C., the reaction pressure is 1.0 MPa (gauge pressure), and the reaction residence time is 30 min;

[0105] Another part of the anhydrous peroxypropionic acid material discharged from the bottom of the reaction distillation tower 7 passes through the circulation pump 14 and then returns to the reaction section 26 from the bottom of the reaction distillation tower through the tower bottom reboiler 13.

[0106] The mass content of anhydrous peroxypropionic acid in the anhydrous peroxypropionic acid material discharged from the bottom of the reactive distillation tower 7 is 21%, and the mass content of the water-carrying agent is 21%.

[0107] After stabilization, the reaction product of the Baeyer-Villiger oxidation reaction was analyzed to have a cyclohexanone conversion of 99.5% and an ε-caprolactone selectivity of 99.5%.

[0108] Example 2

[0109] A 50% by mass hydrogen peroxide solution 3, a catalyst (98% by mass concentrated sulfuric acid) and an organic acid (propionic acid) are mixed to obtain a catalyst-containing organic acid mixed solution 2, which enters a reaction distillation tower 7 after being metered by a metering pump 6 and a metering pump 5, and after being evenly distributed by a liquid phase distributor 25 located in the middle of the reaction distillation tower 7, the liquid phase flows into a reaction section 26 (a packed tower, in which the packing in the packed tower is a random packing of glass fiber springs) of the reaction distillation tower 7 to undergo a catalytic reaction to generate peroxy organic acid and water; wherein the amount of the catalyst used is 1% of the mass of the feed of the 50% by mass hydrogen peroxide solution 3;

[0110] The water-carrying agent 1 (ethyl propionate) is metered by the metering pump 4 and enters from the middle of the rectifying section 24 (a plate tower with a theoretical number of 5 plates) of the reaction distillation tower 7. In the reaction distillation tower, the water generated in the reaction section 26 contacts with the water-carrying agent descending from the rectifying section 24 and is heated by the tower kettle reboiler 13 and then withdrawn with the gas. The gas phase rising from the reaction section 26 enters the rectifying section. In the rectifying section 24, the mixture containing the water-carrying agent and water is distilled from the top of the tower, condensed by the condenser 8, and enters the water separator 10. The upper organic phase in the water separator 10 is discharged from the upper part of the rectifying section 24 by the reflux pump 9. The reaction distillation tower 7 is refluxed to the reaction distillation tower 7, and continues to descend to the reaction section of the reaction distillation tower 7, and the lower aqueous phase enters the wastewater treatment unit 12; wherein, the molar ratio of ethyl propionate to hydrogen peroxide in the hydrogen peroxide solution 3 is 1.5:1, the molar ratio of propionic acid to hydrogen peroxide in the hydrogen peroxide solution 3 is 4:1, the reflux ratio of the upper organic phase is 2, and the operating pressure of the reaction distillation tower 7 is controlled to be 100mbar by a vacuum pump connected to the water separator 10, the temperature of the reaction section 26 is 65°C, and the condensation temperature is 10°C; the temperature of the tower kettle reboiler 13 is 80°C;

[0111] The anhydrous peroxypropionic acid material discharged from the bottom of the reaction distillation tower 7 passes through the circulation pump 14, and then partially passes through the filter 17 and is metered by the metering pump 20, and then enters the microscale reactor 22 with an equivalent diameter of 1000 μm for Baeyer-Villiger oxidation reaction together with the raw ketone compound 16 (cyclohexanone) metered by the metering pump 19, and the reaction product enters the subsequent separation unit 23 for separation; wherein, the conditions of the Baeyer-Villiger oxidation reaction are: the molar ratio of anhydrous peroxypropionic acid to cyclohexanone in the anhydrous peroxypropionic acid material is 1.1:1, the reaction temperature is 90°C, the reaction pressure is: normal pressure, and the reaction residence time is 30 min;

[0112] Another part of the anhydrous peroxypropionic acid material discharged from the bottom of the reaction distillation tower 7 passes through the circulation pump 14 and then returns to the reaction section 26 from the bottom of the reaction distillation tower through the tower bottom reboiler 13.

[0113] The mass content of anhydrous peroxypropionic acid discharged from the bottom of the reactive distillation tower 7 is 21% of anhydrous peroxy organic acid, and the mass content of water-carrying agent is 21%.

[0114] The reaction product of the Baeyer-Villiger oxidation reaction was analyzed, and the cyclohexanone conversion was 98%, and the ε-caprolactone selectivity was 98%.

[0115] Example 3

[0116] A 50% by mass hydrogen peroxide solution 3, a catalyst (98% by mass concentrated sulfuric acid) and an organic acid (propionic acid) are mixed to obtain a catalyst-containing organic acid mixed solution 2, which enters a reaction distillation tower 7 after being metered by a metering pump 6 and a metering pump 5, and after being evenly distributed by a liquid phase distributor 25 located in the middle of the reaction distillation tower 7, the liquid phase flows into a reaction section 26 (a packed tower, in which the packing in the packed tower is a random packing of glass fiber springs) of the reaction distillation tower 7 to undergo a catalytic reaction to generate peroxy organic acid and water; wherein the amount of the catalyst used is 1% of the mass of the feed of the 50% by mass hydrogen peroxide solution 3;

[0117] The water-carrying agent 1 (ethyl propionate) is metered by the metering pump 4 and enters from the middle of the distillation section 24 (a plate tower with a theoretical number of 5 plates) of the reaction distillation tower 7. In the reaction distillation tower, the water generated in the reaction section 26 contacts with the water-carrying agent descending from the distillation section 24 and is heated by the tower bottom reboiler 13 and then withdrawn with the gas. The gas phase rising from the reaction section 26 enters the distillation section. In the distillation section 24, the mixture containing the water-carrying agent and water is distilled from the top of the tower, condensed by the condenser 8, and enters the water separator 10. The upper organic phase in the water separator 10 is refluxed from the top of the distillation section 24 by the reflux pump 9. Flow into the reaction distillation tower 7, continue to descend to the reaction section of the reaction distillation tower 7, and the lower aqueous phase enters the wastewater treatment unit 12; wherein, the molar ratio of ethyl propionate to hydrogen peroxide in the hydrogen peroxide solution 3 is 1.5:1, the molar ratio of propionic acid to hydrogen peroxide in the hydrogen peroxide solution 3 is 4:1, the reflux ratio of the upper organic phase is 2, and the operating pressure of the reaction distillation tower 7 is controlled to be 100 mbar (gauge pressure) by a vacuum pump connected to the water separator 10, the temperature of the reaction section 26 is 65°C, and the condensation temperature is 10°C; the temperature of the tower kettle reboiler 13 is 80°C;

[0118] The anhydrous peroxypropionic acid material discharged from the bottom of the reaction distillation tower 7 passes through the circulation pump 14, and then partially passes through the filter 17 and is metered by the metering pump 20, and then enters the microscale reactor 22 with an equivalent diameter of 1000 μm for Baeyer-Villiger oxidation reaction together with the raw ketone compound 16 (cyclohexanone) metered by the metering pump 19, and the reaction product enters the subsequent separation unit 23 for separation; wherein, the conditions of the Baeyer-Villiger oxidation reaction are: the molar ratio of anhydrous peroxypropionic acid to cyclohexanone in the anhydrous peroxypropionic acid material is 1.1:1, the reaction temperature is 80°C, the reaction pressure is: normal pressure, and the reaction residence time is 30 min;

[0119] Another part of the anhydrous peroxypropionic acid material discharged from the bottom of the reaction distillation tower 7 passes through the circulation pump 14 and then returns to the reaction section 26 from the bottom of the reaction distillation tower through the tower bottom reboiler 13.

[0120] The mass content of anhydrous peroxypropionic acid discharged from the bottom of the reactive distillation tower 7 is 21% of anhydrous peroxy organic acid, and the mass content of water-carrying agent is 21%.

[0121] The reaction product of the Baeyer-Villiger oxidation reaction was analyzed, and the cyclohexanone conversion was 98%, and the ε-caprolactone selectivity was 99%.

[0122] Example 4

[0123] A 50% by mass hydrogen peroxide solution 3, a catalyst (98% by mass concentrated sulfuric acid) and an organic acid (propionic acid) are mixed to obtain a catalyst-containing organic acid mixed solution 2, which enters a reaction distillation tower 7 after being metered by a metering pump 6 and a metering pump 5, and after being evenly distributed by a liquid phase distributor 25 located in the middle of the reaction distillation tower 7, the liquid phase flows into a reaction section 26 (a packed tower, in which the packing in the packed tower is a random packing of glass fiber springs) of the reaction distillation tower 7 to undergo a catalytic reaction to generate peroxy organic acid and water; wherein the amount of the catalyst used is 1% of the mass of the feed of the 50% by mass hydrogen peroxide solution 3;

[0124] The water-carrying agent 1 (ethyl propionate) is metered by the metering pump 4 and enters from the middle of the distillation section 24 (a plate tower with a theoretical number of 5 plates) of the reaction distillation tower 7. In the reaction distillation tower, the water generated in the reaction section 26 contacts with the water-carrying agent descending from the distillation section 24 and is heated by the tower bottom reboiler 13 and then withdrawn with the gas. The gas phase rising from the reaction section 26 enters the distillation section. In the distillation section 24, the mixture containing the water-carrying agent and water is distilled from the top of the tower, condensed by the condenser 8, and enters the water separator 10. The upper organic phase in the water separator 10 is refluxed from the top of the distillation section 24 by the reflux pump 9. Flow into the reaction distillation tower 7, continue to descend to the reaction section of the reaction distillation tower 7, and the lower aqueous phase enters the wastewater treatment unit 12; wherein, the molar ratio of ethyl propionate to hydrogen peroxide in the hydrogen peroxide solution 3 is 1.5:1, the molar ratio of propionic acid to hydrogen peroxide in the hydrogen peroxide solution 3 is 4:1, the reflux ratio of the upper organic phase is 2, and the operating pressure of the reaction distillation tower 7 is controlled to be 100 mbar (gauge pressure) by a vacuum pump connected to the water separator 10, the temperature of the reaction section 26 is 65°C, and the condensation temperature is 10°C; the temperature of the tower kettle reboiler 13 is 80°C;

[0125] The anhydrous peroxypropionic acid material discharged from the bottom of the reaction distillation tower 7 passes through the circulation pump 14, and then partially passes through the filter 17 and is metered by the metering pump 20, and then enters the microscale reactor 22 with an equivalent diameter of 1000 μm together with the raw ketone compound 16 (cyclohexanone) metered by the metering pump 19 to carry out Baeyer-Villiger oxidation reaction, and the reaction product enters the subsequent separation unit 23 for separation; wherein, the conditions of the Baeyer-Villiger oxidation reaction are: the molar ratio of anhydrous peroxypropionic acid to cyclohexanone in the anhydrous peroxypropionic acid material is 1.2:1, the reaction temperature is 80°C, the reaction pressure is normal pressure, and the reaction residence time is 30 min;

[0126] Another part of the anhydrous peroxypropionic acid material discharged from the bottom of the reaction distillation tower 7 passes through the circulation pump 14 and then returns to the reaction section 26 from the bottom of the reaction distillation tower through the tower bottom reboiler 13.

[0127] The mass content of anhydrous peroxypropionic acid in the anhydrous peroxypropionic acid material discharged from the bottom of the reactive distillation tower 7 is 21%, and the mass content of the water-carrying agent is 21%;

[0128] The reaction product of the Baeyer-Villiger oxidation reaction was analyzed, and the cyclohexanone conversion was 98.5%, and the ε-caprolactone selectivity was 99.3%.

[0129] Example 5

[0130] A 50% by mass hydrogen peroxide solution 3, a catalyst (boric acid) and an organic acid (propionic acid) are mixed to obtain a catalyst-containing organic acid mixed solution 2, which is metered by a metering pump 6 and a metering pump 5 respectively and then enters a reaction distillation tower 7. After being evenly distributed by a liquid phase distributor 25 located in the middle of the reaction distillation tower 7, the liquid phase flows into a reaction section 26 (a packed tower, in which the packing is a random packing of glass fiber springs) of the reaction distillation tower 7 to undergo a catalytic reaction to generate peroxy organic acid and water; wherein the amount of the catalyst used is 1% of the mass of the feed of the 50% by mass hydrogen peroxide solution 3;

[0131] The water-carrying agent 1 (ethyl propionate) is metered by the metering pump 4 and enters from the middle of the distillation section 24 (a plate tower with a theoretical number of 5 plates) of the reaction distillation tower 7. In the reaction distillation tower, the water generated in the reaction section 26 contacts with the water-carrying agent descending from the distillation section 24 and is heated by the tower bottom reboiler 13 and then withdrawn with the gas. The gas phase rising from the reaction section 26 enters the distillation section. In the distillation section 24, the mixture containing the water-carrying agent and water is distilled from the top of the tower, condensed by the condenser 8, and enters the water separator 10. The upper organic phase in the water separator 10 is refluxed from the top of the distillation section 24 by the reflux pump 9. Flow into the reaction distillation tower 7, continue to descend to the reaction section of the reaction distillation tower 7, and the lower aqueous phase enters the wastewater treatment unit 12; wherein, the molar ratio of ethyl propionate to hydrogen peroxide in the hydrogen peroxide solution 3 is 1.5:1, the molar ratio of propionic acid to hydrogen peroxide in the hydrogen peroxide solution 3 is 4:1, the reflux ratio of the upper organic phase is 2, and the operating pressure of the reaction distillation tower 7 is controlled to be 100 mbar (gauge pressure) by a vacuum pump connected to the water separator 10, the temperature of the reaction section 26 is 65°C, and the condensation temperature is 10°C; the temperature of the tower kettle reboiler 13 is 80°C;

[0132] The anhydrous peroxypropionic acid material discharged from the bottom of the reaction distillation tower 7 passes through the circulation pump 14, and then partially passes through the filter 17 and is metered by the metering pump 20, and then enters the microscale reactor 22 with an equivalent diameter of 1000 μm together with the raw ketone compound 16 (cyclohexanone) metered by the metering pump 19 to carry out Baeyer-Villiger oxidation reaction, and the reaction product enters the subsequent separation unit 23 for separation; wherein, the conditions of the Baeyer-Villiger oxidation reaction are: the molar ratio of anhydrous peroxypropionic acid to cyclohexanone in the anhydrous peroxypropionic acid material is 1.2:1, the reaction temperature is 80°C, the reaction pressure is normal pressure, and the reaction residence time is 30 min;

[0133] Another part of the anhydrous peroxypropionic acid material discharged from the bottom of the reaction distillation tower 7 passes through the circulation pump 14 and then returns to the reaction section 26 from the bottom of the reaction distillation tower through the tower bottom reboiler 13.

[0134] The mass content of anhydrous peroxypropionic acid in the anhydrous peroxypropionic acid material discharged from the bottom of the reactive distillation tower 7 is 21.5%, and the mass content of the water-carrying agent is 20.6%;

[0135] The reaction product of the Baeyer-Villiger oxidation reaction was analyzed, and the cyclohexanone conversion was 98.6%, and the ε-caprolactone selectivity was 99.4%.

[0136] Example 6

[0137] A 50% by mass hydrogen peroxide solution 3, a catalyst (boric acid) and an organic acid (propionic acid) are mixed to obtain a catalyst-containing organic acid mixed solution 2, which is metered by a metering pump 6 and a metering pump 5 respectively and then enters a reaction distillation tower 7. After being evenly distributed by a liquid phase distributor 25 located in the middle of the reaction distillation tower 7, the liquid phase flows into a reaction section 26 (a packed tower, in which the packing is a random packing of glass fiber springs) of the reaction distillation tower 7 to undergo a catalytic reaction to generate peroxy organic acid and water; wherein the amount of the catalyst used is 1% of the mass of the feed of the 50% by mass hydrogen peroxide solution 3;

[0138] The water-carrying agent 1 (ethyl propionate) is metered by the metering pump 4 and enters from the middle of the rectifying section 24 (a plate tower with a theoretical number of 5 plates) of the reaction distillation tower 7. In the reaction distillation tower, the water generated in the reaction section 26 contacts with the water-carrying agent descending from the rectifying section 24 and is heated by the tower kettle reboiler 13 and then extracted with the gas. The gas phase rising from the reaction section 26 enters the rectifying section. In the rectifying section 24, the mixture containing the water-carrying agent and water is distilled from the top of the tower, condensed by the condenser 8, and then enters the water separator 10. The upper organic phase in the water separator 10 is discharged from the top of the rectifying section 24 by the reflux pump 9. Reflux into the reaction distillation tower 7, continue to descend to the reaction section of the reaction distillation tower 7, and the lower aqueous phase enters the wastewater treatment unit 12; wherein, the molar ratio of ethyl propionate to hydrogen peroxide in the hydrogen peroxide solution 3 is 1.5:1, the molar ratio of propionic acid to hydrogen peroxide in the hydrogen peroxide solution 3 is 4:1, the reflux ratio of the upper organic phase is 2, and the operating pressure of the reaction distillation tower 7 is controlled to be 100 mbar (gauge pressure) by a vacuum pump connected to the water separator 10, the temperature of the reaction section 26 is 65°C, and the condensation temperature is 10°C; the temperature of the tower kettle reboiler 13 is 80°C;

[0139] The anhydrous peroxy propionic acid material discharged from the bottom of the reaction distillation tower 7 is divided into two streams of anhydrous peroxy propionic acid materials after passing through the circulation pump 14. One stream of anhydrous peroxy organic acid material is filtered through the filter 17 and metered by the metering pump 20. It enters the microscale reactor 22 with an equivalent diameter of 1000 μm together with the raw ketone compound 16 (cyclohexanone) metered by the metering pump 19 to carry out Baeyer-Villiger oxidation reaction. The other stream of anhydrous peroxy propionic acid material is filtered through the valve 15 and the filter 18, enters the metering pump 21 for metering, and then enters the microscale reactor 22 with an equivalent diameter of 1000 μm for Baeyer-Villiger oxidation reaction. The Baeyer-Villiger oxidation reaction is carried out by introducing the anhydrous peroxy organic acid material in the middle section of the scale reactor 22 (the volume ratio of the first stream of anhydrous peroxy organic acid material to the second stream of anhydrous peroxy organic acid material is 1.2:1), and the reaction product enters the subsequent separation unit 23 for separation; wherein, the conditions of the Baeyer-Villiger oxidation reaction are: the molar ratio of anhydrous peroxy propionic acid to cyclohexanone in the anhydrous peroxy propionic acid material is 1.2:1, the reaction temperature is 80°C, the reaction pressure is 1.0 MPa (gauge pressure), and the reaction residence time is 30 min;

[0140] Another part of the anhydrous peroxypropionic acid material discharged from the bottom of the reaction distillation tower 7 passes through the circulation pump 14 and then returns to the reaction section 26 from the bottom of the reaction distillation tower through the tower bottom reboiler 13.

[0141] The mass content of anhydrous peroxypropionic acid in the anhydrous peroxypropionic acid material discharged from the bottom of the reactive distillation tower 7 is 21.5%, and the mass content of the water-carrying agent is 20.6%;

[0142] The reaction product of the Baeyer-Villiger oxidation reaction was analyzed, and the cyclohexanone conversion was 99.5%, and the ε-caprolactone selectivity was 99.6%.

[0143] Example 7

[0144] The method of Example 6 is followed, except that:

[0145] The reflux ratio of the organic phase was 3.

[0146] The mass content of anhydrous peroxypropionic acid in the anhydrous peroxypropionic acid material discharged from the bottom of the reactive distillation tower 7 is 21.6%, and the mass content of the water-carrying agent is 20.5%;

[0147] The reaction product of the Baeyer-Villiger oxidation reaction was analyzed, and the cyclohexanone conversion was 99.5%, and the ε-caprolactone selectivity was 99.6%.

[0148] Comparative Example 1

[0149] The method of Example 6 is followed, except that:

[0150] After being metered by the metering pump 4, the water-carrying agent 1 (ethyl propionate) is evenly distributed through the liquid phase distributor 25 located in the middle of the reaction distillation tower 7, and then the liquid phase flows into the reaction section 26 of the reaction distillation tower 7 (that is, it does not enter the reaction distillation tower 7 through the distillation section 24); the rest is the same as Example 6.

[0151] The mass content of anhydrous peroxypropionic acid in the anhydrous peroxypropionic acid material discharged from the bottom of the reactive distillation tower 7 is 19%, and the mass content of the water-carrying agent is 22.9%;

[0152] The reaction product of the Baeyer-Villiger oxidation reaction was analyzed, and the cyclohexanone conversion was 96%, and the ε-caprolactone selectivity was 96%.

[0153] Comparative Example 2

[0154] The most advanced synthesis process of ε-caprolactone is as follows: in an intermittent stirred tank, 50 wt% of hydrogen peroxide aqueous solution, propionic acid, ethyl propionate and a catalyst (98% concentrated sulfuric acid by mass fraction) are added, and the proportions are the same as those in Example 6. The reaction pressure and temperature are the same as those in Example 1. Under the above process conditions, the reaction is carried out for 3 hours, and the liquid in the stirred tank is a peroxypropionic acid material. After analysis, the peroxypropionic acid content in the peroxypropionic acid material is 16.02%;

[0155] The generated peroxypropionic acid material and cyclohexanone were added to another intermittent stirred tank according to the molar ratio of Example 1 for reaction. The reaction conditions were the same as in Example 1. The reaction was continued for 5 hours, and the cyclohexanone conversion rate was 98.5%, and the ε-caprolactone selectivity was 99.0%.

[0156] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A method for preparing anhydrous peroxy organic acid, characterized in that: The preparation method comprises: The hydrogen peroxide solution and the organic acid mixed solution containing the catalyst are respectively injected into the reaction section of the reaction distillation tower to carry out catalytic reaction; The water-carrying agent is injected into the distillation section of the reaction distillation tower located above the reaction section; the water generated by the catalytic reaction and the downward water-carrying agent are gas-lifted to the distillation section, and then distilled from the top of the reaction distillation tower, condensed and phase-separated; the anhydrous peroxyorganic acid material is discharged from the bottom of the reaction distillation tower.

2. The preparation method according to claim 1, wherein The hydrogen peroxide solution and the organic acid mixed solution containing the catalyst are distributed through a liquid phase distributor located between the reaction section and the rectification section and then flow into the reaction section for catalytic reaction; and / or The water-carrying agent is injected into the rectifying section from the upper part, the middle part or the lower part of the rectifying section, preferably from the middle part of the rectifying section; and / or The organic phase obtained by phase separation is refluxed into the reaction distillation tower, and continues to flow down to the reaction section to participate in the catalytic reaction. Preferably, the organic phase is refluxed into the reaction distillation tower from the top of the distillation section, and the reflux ratio of the organic phase is preferably 1.2-3, preferably 1-2.5; and / or The discharged anhydrous peroxy organic acid material is divided into two materials, one material enters the downstream section, and the other material returns to the reaction section after heating. Preferably, the other material returns to the reaction section from the bottom of the reaction distillation tower after heating, and the preferred heating temperature is 70-90°C.

3. The preparation method according to claim 1 or 2, wherein The hydrogen peroxide solution is a hydrogen peroxide aqueous solution with a mass fraction of 30-80%; and / or The organic acid is selected from C1-C6 organic acids, preferably one or more selected from acetic acid, propionic acid and butyric acid; and / or The catalyst comprises a homogeneous catalyst, and preferably the homogeneous catalyst is selected from one or more of phosphoric acid, sulfuric acid, boric acid, methanesulfonic acid and p-toluenesulfonic acid; and / or The water-carrying agent is selected from compounds that can form an azeotropic agent with water, preferably at least one of lower esters, chloroalkanes and cyclic hydrocarbons, and further preferably one or more of ethyl acetate, ethyl propionate, chloroform and cyclohexane.

4. The preparation method according to any one of claims 1 to 3, wherein The amount of the catalyst is 0.1-2 wt% of the mass of the hydrogen peroxide solution; and / or The molar ratio of the water-carrying agent to hydrogen peroxide is 1-4:1, preferably 1.5-3:1; and / or The molar ratio of the organic acid to hydrogen peroxide is 1-6:1, preferably 3-5:1; and / or The reactive distillation tower is operated under negative pressure, preferably at an operating pressure of 10-500 mbar; and / or The temperature of the reaction zone is 40-80°C; and / or The condensation conditions include: the condensation temperature is 5-20°C.

5. The preparation method according to any one of claims 1 to 4, wherein: The distillation section is a plate tower, a packed tower or a composite tower, preferably a plate tower, and more preferably the plate tower has a theoretical plate number of 4-8; and / or The reaction section is a packed tower; Preferably, the packing in the packed tower is in the form of structured packing and / or random packing; and / or The material of the filler in the packed tower is at least one of metal, ceramic, polytetrafluoroethylene, glass fiber and carbon fiber.

6. A device for preparing anhydrous peroxy organic acid, characterized in that: The preparation device comprises: a reaction distillation tower; The reactive distillation tower is provided with a hydrogen peroxide solution feed inlet, a catalyst-containing organic acid mixed solution feed inlet and a water-containing agent feed inlet; The reaction distillation tower comprises a reaction section and a distillation section located above the reaction section, and the water-carrying agent feed port is arranged in the distillation section; The reaction section and the rectification section are separated by a hydrogen peroxide solution feed port and an organic acid mixed solution feed port containing a homogeneous catalyst; The top of the reaction distillation tower is provided with a gas outlet, which is connected to a condenser and a water separator in sequence, and is used for phase separation of the top distillate in the water separator after condensation.

7. The preparation device according to claim 6, wherein: The reactive distillation tower further comprises a liquid phase distributor located between the reaction section and the distillation section, which is used for distributing the hydrogen peroxide solution and the organic acid mixed liquid containing the catalyst and then flowing into the reaction section for catalytic reaction; and / or; The water-carrying agent feed port is located at the upper part, middle part or lower part of the rectification section, preferably at the middle part; and / or The upper part of the water separator is connected to the distillation section via a reflux pump; and / or The bottom of the reaction distillation tower is provided with a bottom liquid phase outlet, and preferably the bottom liquid phase outlet is connected to a circulation pump, and the outlet pipeline of the circulation pump is divided into two paths, one path is connected to the downstream section, and the other path is connected to the bottom of the reaction distillation tower through the tower kettle reboiler.

8. A method for preparing an ester compound from a ketone compound, characterized in that: The method includes: S1 prepare an anhydrous peroxy organic acid material according to the preparation method described in any one of claims 1 to 5; The S2 ketone compound and the anhydrous peroxy organic acid material are respectively introduced into the microscale reaction unit for Baeyer-Villiger oxidation reaction.

9. The preparation method according to claim 8, wherein: The ketone compound is fed in one go; and / or The anhydrous peroxy organic acid material is fed all at once or in stages, preferably in stages; and / or The microscale reaction unit is a microscale reactor composed of a single stage or multiple stages connected in series, and preferably the equivalent diameter of the microscale reactor is 100-2000 μm, preferably 200-1600 μm; and / or The anhydrous peroxy organic acid material is filtered and then enters the microscale reaction unit.

10. The preparation method according to claim 8 or 9, wherein: The molar ratio of the anhydrous peroxy organic acid to the ketone compound in the anhydrous peroxy organic acid material is 1-2:1; and / or The ketone compound is selected from at least one of cyclohexanone, cyclopentanone, acetophenone and cyclohexyl ketone, preferably cyclohexanone; and / or The reaction conditions of the Baeyer-Villiger oxidation reaction include: The reaction temperature is 40-100°C; and / or The reaction pressure is normal pressure to 1.5 MPa, preferably 1 to 1.5 MPa; and / or The reaction residence time is 10-60min.

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