Recovery method and application of methyl ethyl ketazine working solution

Abstract

The invention relates to the technical field of chemical synthesis, in particular to a recovery method and application of a methyl ethyl ketazine working solution, the methyl ethyl ketazine working solution comprises an amide catalyst, an acid ammonium catalyst and water, and the recovery method of the methyl ethyl ketazine working solution comprises two steps: S1, concentration of a methyl ethyl ketazine synthesis reaction solution; s2, the methyl ethyl ketazine working solution is recycled, the target product methyl ethyl ketazine and the recycled methyl ethyl ketazine reaction solution are finally obtained, the tubular reactor is utilized in the methyl ethyl ketazine working solution recycling process, rapid and efficient recycling of the methyl ethyl ketazine working solution is achieved, and compared with an existing methyl ethyl ketazine working solution recycling mode, the reaction efficiency is remarkably improved, and the production cost is reduced. The treatment time is greatly shortened, the method is easier to realize industrial amplification and production, and an innovative and practical technical scheme is provided for efficient synthesis of methyl ethyl ketazine and recovery of the catalyst.

Description

Technical Field

[0001] This invention relates to the field of chemical synthesis technology, and in particular to a method for recovering butanone-azo working solution and its application. Background Technology

[0002] Hydrazine hydrate (N2H4·H2O) is a colorless, fuming liquid with strong alkalinity and high reducing properties. It is a chemical raw material with important industrial value and is widely used in many key fields such as medicine, pesticides, environmental protection, and materials science. For example, it is used as a key intermediate in the synthesis of anticancer drugs (such as isoniazid) and pesticides (such as paclobutrazol). In environmental protection processes, it replaces traditional deoxygenating agents for boiler water deoxygenation, reducing corrosion and causing no pollution. It is also used as a raw material for the preparation of ADC foaming agent, which has the largest usage.

[0003] Currently, there are four main industrial production methods for hydrazine hydrate: the Raschig process, the urea process, the acetone-hydrazine process, and the hydrogen peroxide process. The Raschig process is highly polluting and has low production efficiency; production processes using this method have been phased out. The urea process has high raw material costs, causes significant equipment corrosion, and is difficult to treat wastewater. The acetone-hydrazine process requires the treatment of organic byproducts and acetone vapor, resulting in high energy consumption. The hydrogen peroxide process uses hydrogen peroxide as an oxidant, avoiding corrosion and pollution problems, and is currently the most environmentally friendly industrial production method for hydrazine hydrate.

[0004] The hydrogen peroxide process is currently a relatively environmentally friendly process for producing hydrazine hydrate. It uses hydrogen peroxide as an oxidant to oxidize ammonia and ketone compounds in the presence of a catalyst, generating a ketone azide intermediate, which is then hydrolyzed to obtain hydrazine hydrate. In the hydrogen peroxide process, methyl ethyl ketone azide is an important intermediate used in the subsequent hydrolysis reaction. Commonly used catalysts in the hydrogen peroxide process are amide compounds, such as formamide, acetamide, and acrylamide. During the reaction, these amide compounds hydrolyze to generate ammonium acid compounds. Therefore, improving the yield of methyl ethyl ketone azide and increasing the catalyst recovery rate are key issues in the preparation of hydrazine hydrate using the hydrogen peroxide process.

[0005] US3943152 discloses a method for preparing aziridine compounds, which can improve the yield of butanone azo synthesis, but does not provide a clear method for post-treatment of the working solution after the reaction.

[0006] In the review of research on catalysts for the synthesis of ketadiazine by hydrogen peroxide by Guo Xiaoran (Guo Xiaoran, Lou Fenglei, Shen Chong, et al. Research on the synthesis of ketadiazine by hydrogen peroxide [C] / / Proceedings of the 2013 Annual Meeting of the Peroxide Branch of China Inorganic Salts Industry Association. 2013: 131-134.), only the pyrolysis recovery method of the catalyst was briefly mentioned, lacking in-depth discussion and optimization schemes.

[0007] Patent CN114380708A discloses a method for recovering catalysts used in the synthesis of hydrated hydrazine intermediates. Although this method can efficiently recover amides from the working solution, it uses a batch reactor for recovery. The batch reactor has a relatively small heat transfer area and low heat transfer efficiency, which can easily lead to excessively high or low local temperatures, affecting the uniformity of the reaction. Furthermore, due to the severe backmixing phenomenon in the batch reactor, the residence time of the reactants is widely distributed, which can easily lead to side reactions and reduce the yield of the target product.

[0008] In summary, although there are various methods for producing hydrazine hydrate, the current problem of low catalyst recovery efficiency in the reaction solution after the synthesis reaction remains. In addition, existing recovery methods often fail to improve catalyst recovery efficiency while maintaining the yield of the important intermediate product, methyl ethyl ketone (MEK). This contradiction severely restricts the overall efficiency and economy of hydrazine hydrate production. Therefore, it is urgent to develop an efficient method for recovering and treating MEK working solution to solve the core problem of low catalyst recovery efficiency and further optimize the yield of MEK, thereby providing strong technical support for the sustainable development of the hydrazine hydrate industry. Summary of the Invention

[0009] The purpose of this invention is to provide a method for recovering methyl ethyl ketone (MEK) working solution, so as to overcome at least one of the problems in the prior art, such as the inability to efficiently recover catalysts, poor reusability, and inability to simultaneously achieve MEK yield.

[0010] On one hand, the present invention relates to a method for recovering methyl ethyl ketone (MEK) working solution using a tubular reactor:

[0011] The methyl ethyl ketone (MEK) is an intermediate product of hydrazine hydrate obtained by the hydrogen peroxide process. The MEK working solution includes an amide catalyst, an ammonium acid catalyst, and water.

[0012] The method for recovering the butanone-azo working solution specifically includes the following steps:

[0013] S1. Concentration of the methyl ethyl ketone (MEK) azide synthesis reaction solution: The MEK azide synthesis reaction solution is concentrated to obtain a concentrated solution.

[0014] Furthermore, the water content of the concentrate is 1-10%;

[0015] Furthermore, the concentrated solution has a water content of 1-5%.

[0016] Furthermore, the concentration methods for the butanone azo synthesis reaction solution include, but are not limited to, flash concentration and distillation concentration;

[0017] Furthermore, the butanone azo synthesis reaction solution is concentrated by flash evaporation.

[0018] S2. Recovery of methyl ethyl ketone (MEK) working solution: The concentrate is continuously passed through a tubular reactor to recover the working solution, obtaining MEK and the recovered MEK working solution.

[0019] Furthermore, the processing temperature of the tubular reactor is 100-200℃, preferably 130-170℃.

[0020] Furthermore, the processing pressure of the tubular reactor is 1-2 MPa, preferably 1-1.5 MPa.

[0021] Furthermore, the residence time of the concentrate in the tubular reactor is 5-10 min, preferably 6-8 min.

[0022] The amide catalyst in the methyl ethyl ketone (MEK) working solution is at least one of formamide, acetamide, propionamide, acrylamide, and butyramide; the ammonium acid catalyst is at least one of ammonium formate, ammonium acetate, ammonium propionate, ammonium acrylate, and ammonium butyrate.

[0023] On the other hand, the invention also relates to the use of the butanone-azo working solution obtained by the recovery method in the preparation of butanone-azo reaction.

[0024] Compared with the prior art, the beneficial effects of the present invention are:

[0025] 1. By continuously recovering the concentrated methyl ethyl ketone (MEK) hydrazine synthesis reaction solution through a tubular reactor, the catalyst components in the MEK hydrazine synthesis reaction solution are efficiently recovered and reused. Compared with the traditional batch reactor method for recovering MEK hydrazine working solution, the recovery rate of MEK hydrazine working solution using a tubular reactor for continuous recovery can be increased from 48.2% to 99.5%. The yield of MEK hydrazine can also be increased from 56.3% to 97.0% when using the recovered MEK hydrazine working solution for the MEK hydrazine synthesis reaction.

[0026] The method of this invention not only improves the utilization rate of catalysts and reduces production costs, but also reduces waste emissions, which is in line with the concepts of green chemistry and sustainable development, while ensuring the quality and production efficiency of methyl ethyl ketone (MEK) products.

[0027] 2. Tubular reactors not only have a relatively simple structure, occupy little space, and have low investment costs, but they also enable precise control of processing conditions. When the processing temperature of the tubular reactor is 100-200℃, the processing pressure is 1-2MPa, and the residence time of the concentrated methyl ethyl ketone (MEK) synthesis reaction solution in the tubular reactor is 5-10 minutes, the recovery rate of the MEK working solution treated by the tubular reactor can be stably above 99%, and the yield of MEK synthesized using the recovered MEK working solution can be stably above 96%.

[0028] 3. Before the recovery reaction of the methyl ethyl ketone (MEK) azo working solution, the MEK azo synthesis reaction solution is concentrated to obtain a concentrated solution. This can significantly increase the catalyst concentration in the MEK azo synthesis reaction solution and reduce the hydrolysis of amide catalysts. Especially when the water content of the concentrated solution is between 1% and 10%, the residence time of the concentrated solution in the tubular reactor is only 5 minutes, and the recovery rate of the MEK azo working solution can reach 99.1%. The yield of MEK azo synthesized using the recovered MEK azo working solution can reach 96.1%. Detailed Implementation

[0029] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0030] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0031] The methyl ethyl ketone (MEK) working solution used in the embodiments of the present invention is a working solution for the synthesis of MEK catalyzed by formamide. Before the MEK synthesis reaction, the total mass of the MEK working solution is 100g, of which the formamide content is 53%, the ammonium formate content is 34%, and the water content is 13%. After the MEK synthesis reaction is completed, the total mass of the aqueous phase recovered after removing the organic phase from the MEK synthesis reaction solution is 120g. The aqueous phase was determined by liquid chromatography and found to contain approximately 35% formamide, 41% ammonium formate, and 24% water. The increase in water content is due to the introduction of hydrogen peroxide and the generation of water in the MEK synthesis reaction.

[0032] The method for synthesizing methyl ethyl ketone (MEK) is as follows: 100g of the recovered MEK working solution is placed in a three-necked flask, and 55g of MEK, 25g of hydrogen peroxide (concentration 50%), and 20g of ammonia are added. The reaction temperature is 50℃, the reaction pressure is atmospheric pressure, and the reaction time is 4h to obtain the MEK synthesis reaction solution.

[0033] After the reaction is complete, the yield of methyl ethyl ketone (MEK) can be determined by gas chromatography. The recovery rate of MEK working solution can be obtained by measuring the mass of formamide in the recovered MEK working solution by liquid chromatography and comparing it with the formamide content in the MEK working solution before the reaction.

[0034] Example 1

[0035] The reaction solution of butanone azo synthesis was added to a flash tank. The concentration conditions of the flash tank were: pressure of 5 kPa absolute and temperature of 75°C.

[0036] After concentrating the water content of the methyl ethyl ketone (MEK) azo synthesis reaction solution to 10%, it was introduced into a coil reactor with an inner diameter of 3 mm and a total length of 6 m. The processing conditions of the coil reactor were: a processing temperature of 160 °C, a processing pressure of 1 MPa, and a processing time of 7 min. Samples were taken for analysis after the reaction was completed.

[0037] The recovery rate of the recovered methyl ethyl ketone (MEK) working solution was 99.2% as determined by chromatographic detection.

[0038] The recovered methyl ethyl ketone (MEK) working solution was used to synthesize MEK according to the MEK synthesis method, with a yield of 96.1%.

[0039] Example 2

[0040] Using the same equipment and control methods as in Example 1, the reacted methyl ethyl ketone (MEK) azide synthesis reaction solution was added to a flash evaporation and concentration device. After concentrating the water content of the MEK azide synthesis reaction solution to 5%, it was then introduced into a tubular reactor. The processing conditions of the tubular reactor were: a processing temperature of 160°C, a processing pressure of 1 MPa, and a processing time of 7 min. Samples were taken for analysis after the reaction was completed.

[0041] The recovery rate of the recovered methyl ethyl ketone (MEK) working solution was 99.5% as determined by chromatographic detection.

[0042] The recovered methyl ethyl ketone (MEK) working solution was used to synthesize MEK according to the MEK synthesis method, and the yield of MEK was 97.0%.

[0043] Example 3

[0044] Using the same equipment and control methods as in Example 1, the reacted methyl ethyl ketone (MEK) azide synthesis reaction solution was added to a flash evaporation and concentration device. After concentrating the water content of the MEK azide synthesis reaction solution to 1%, it was then introduced into a tubular reactor. The processing conditions of the tubular reactor were: a processing temperature of 160°C, a processing pressure of 1 MPa, and a processing time of 7 min. Samples were taken for analysis after the reaction was completed.

[0045] The recovery rate of the recovered methyl ethyl ketone (MEK) working solution was 99.7% as determined by chromatographic detection.

[0046] The recovered methyl ethyl ketone (MEK) working solution was used to synthesize MEK according to the MEK synthesis method, and the yield of MEK was 97.1%.

[0047] Example 4

[0048] Using the same equipment and control method as in Example 1, the reacted methyl ethyl ketone (MEK) azide synthesis reaction solution was added to a flash evaporation and concentration device. After concentrating the water content of the MEK azide synthesis reaction solution to 5%, it was then introduced into a tubular reactor. The processing conditions of the tubular reactor were: a processing temperature of 100°C, a processing pressure of 1 MPa, and a processing time of 7 min. Samples were taken for analysis after the reaction was completed.

[0049] The recovery rate of the recovered methyl ethyl ketone (MEK) working solution was 99.0% as determined by chromatographic detection.

[0050] The recovered methyl ethyl ketone (MEK) working solution was used to synthesize MEK according to the MEK synthesis method, and the yield of MEK was 96.2%.

[0051] Example 5

[0052] Using the same equipment and control methods as in Example 1, the reacted methyl ethyl ketone (MEK) azide synthesis reaction solution was added to a flash evaporation and concentration device. After concentrating the water content of the MEK azide synthesis reaction solution to 5%, it was then introduced into a tubular reactor. The processing conditions of the tubular reactor were: a processing temperature of 170°C, a processing pressure of 1 MPa, and a processing time of 7 min. Samples were taken for analysis after the reaction was completed.

[0053] The recovery rate of the recovered methyl ethyl ketone (MEK) working solution was 99.8% as determined by chromatographic detection.

[0054] The recovered methyl ethyl ketone (MEK) working solution was used to synthesize MEK according to the MEK synthesis method, and the yield of MEK was 97.1%.

[0055] Example 6

[0056] Using the same equipment and control method as in Example 1, the reacted methyl ethyl ketone (MEK) azide synthesis reaction solution was added to a flash evaporation and concentration device. After concentrating the water content of the MEK azide synthesis reaction solution to 5%, it was then introduced into a tubular reactor. The processing conditions of the tubular reactor were: a processing temperature of 160°C, a processing pressure of 1.5 MPa, and a processing time of 7 min. Samples were taken for analysis after the reaction was completed.

[0057] The recovery rate of the recovered methyl ethyl ketone (MEK) working solution was 99.7% as determined by chromatographic detection.

[0058] The recovered methyl ethyl ketone (MEK) working solution was used to synthesize MEK according to the MEK synthesis method, and the yield of MEK was 97.0%.

[0059] Example 7

[0060] Using the same equipment and control methods as in Example 1, the reacted methyl ethyl ketone (MEK) azide synthesis reaction solution was added to a flash evaporation and concentration device. After concentrating the water content of the MEK azide synthesis reaction solution to 5%, it was then introduced into a tubular reactor. The processing conditions of the tubular reactor were: a processing temperature of 160°C, a processing pressure of 2 MPa, and a processing time of 5 min. Samples were taken for analysis after the reaction was completed.

[0061] The recovery rate of the recovered methyl ethyl ketone (MEK) working solution was 99.2% as determined by chromatographic detection.

[0062] The recovered methyl ethyl ketone (MEK) working solution was used to synthesize MEK according to the MEK synthesis method, and the yield of MEK was 96.1%.

[0063] Example 8

[0064] Using the same equipment and control methods as in Example 1, the reacted methyl ethyl ketone (MEK) azide synthesis reaction solution was added to a flash evaporation and concentration device. After concentrating the water content of the MEK azide synthesis reaction solution to 5%, it was then introduced into a tubular reactor. The processing conditions of the tubular reactor were: a processing temperature of 160°C, a processing pressure of 1 MPa, and a processing time of 5 min. Samples were taken for analysis after the reaction was completed.

[0065] The recovery rate of the recovered methyl ethyl ketone (MEK) working solution was 99.1% as determined by chromatographic detection.

[0066] The recovered methyl ethyl ketone (MEK) working solution was used to synthesize MEK according to the MEK synthesis method, and the yield of MEK was 96.1%.

[0067] Example 9

[0068] Using the same equipment and control methods as in Example 1, the reacted methyl ethyl ketone (MEK) azide synthesis reaction solution was added to a flash evaporation and concentration device. After concentrating the water content of the MEK azide synthesis reaction solution to 5%, it was then introduced into a tubular reactor. The processing conditions of the tubular reactor were: a processing temperature of 160°C, a processing pressure of 1 MPa, and a processing time of 10 min. Samples were taken for analysis after the reaction was completed.

[0069] The recovery rate of the recovered methyl ethyl ketone (MEK) working solution was 99.5% as determined by chromatographic detection.

[0070] The recovered methyl ethyl ketone (MEK) working solution was used to synthesize MEK according to the MEK synthesis method, and the yield of MEK was 97.0%.

[0071] Example 10

[0072] Using the same equipment and control methods as in Example 1, the reacted methyl ethyl ketone (MEK) azide synthesis reaction solution was added to a flash evaporation and concentration device. After concentrating the water content of the MEK azide synthesis reaction solution to 5%, it was then introduced into a tubular reactor. The processing conditions of the tubular reactor were: a processing temperature of 200°C, a processing pressure of 1 MPa, and a processing time of 7 min. Samples were taken for analysis after the reaction was completed.

[0073] The recovery rate of the recovered methyl ethyl ketone (MEK) working solution was 99.7% as determined by chromatographic detection.

[0074] The recovered methyl ethyl ketone (MEK) working solution was used to synthesize MEK according to the MEK synthesis method, and the yield of MEK was 97.1%.

[0075] Comparative Example 1

[0076] Using the same equipment and control methods as in Example 1, the reacted methyl ethyl ketone (MEK) azide synthesis reaction solution was added to a flash evaporation and concentration device. After concentrating the water content of the MEK azide synthesis reaction solution to 15%, it was then introduced into a tubular reactor. The processing conditions of the tubular reactor were: a processing temperature of 160°C, a processing pressure of 1 MPa, and a processing time of 7 min. Samples were taken for analysis after the reaction was completed.

[0077] The recovery rate of the recovered methyl ethyl ketone (MEK) working solution was 85.2% as determined by chromatographic detection.

[0078] The recovered methyl ethyl ketone (MEK) working solution was used to synthesize MEK according to the MEK synthesis method, and the yield of MEK was 90.5%.

[0079] Comparative Example 2

[0080] Using the same equipment and control method as in Example 1, the reacted methyl ethyl ketone (MEK) azide synthesis reaction solution was added to a flash evaporation and concentration device. After the water content of the MEK azide synthesis reaction solution was concentrated to 0.5%, ammonium formate crystals precipitated in the flash evaporation and concentration device and could not enter the tubular reactor in a liquid phase, making it impossible to carry out subsequent experiments.

[0081] Comparative Example 3

[0082] Using the same equipment and control methods as in Example 1, the reacted methyl ethyl ketone (MEK) azide synthesis reaction solution was added to a flash evaporation and concentration device. After concentrating the water content of the MEK azide synthesis reaction solution to 5%, it was then introduced into a tubular reactor. The processing conditions of the tubular reactor were: a processing temperature of 80°C, a processing pressure of 1 MPa, and a processing time of 7 min. Samples were taken for analysis after the reaction was completed.

[0083] The recovery rate of the recovered methyl ethyl ketone (MEK) working solution was 59.8% as determined by chromatographic detection.

[0084] The recovered methyl ethyl ketone (MEK) working solution was used to synthesize MEK according to the MEK synthesis method, and the yield of MEK was 60.1%.

[0085] Comparative Example 4

[0086] Using the same equipment and control methods as in Example 1, the reacted methyl ethyl ketone (MEK) azide synthesis reaction solution was added to a flash evaporation and concentration device. After concentrating the water content of the MEK azide synthesis reaction solution to 5%, it was then introduced into a tubular reactor. The processing conditions of the tubular reactor were: a processing temperature of 210°C, a processing pressure of 1 MPa, and a processing time of 7 min. Samples were taken for analysis after the reaction was completed.

[0087] The recovery rate of the recovered methyl ethyl ketone (MEK) working solution was 99.2% as determined by chromatographic detection.

[0088] The recovered methyl ethyl ketone (MEK) working solution was used to synthesize MEK according to the MEK synthesis method, and the yield of MEK was 96.1%.

[0089] Comparative Example 5

[0090] Using the same equipment and control methods as in Example 1, the reacted methyl ethyl ketone (MEK) azide synthesis reaction solution was added to a flash evaporation and concentration device. After concentrating the water content of the MEK azide synthesis reaction solution to 5%, it was then introduced into a tubular reactor. The processing conditions of the tubular reactor were: processing temperature set at 220°C, processing pressure at 1 MPa, and processing time at 7 min. Samples were taken for analysis after the reaction was completed.

[0091] The recovery rate of the recovered methyl ethyl ketone (MEK) working solution was 99.2% as determined by chromatographic detection.

[0092] The recovered methyl ethyl ketone (MEK) working solution was used to synthesize MEK according to the MEK synthesis method, and the yield of MEK was 96.1%.

[0093] Comparative Example 6

[0094] Using the same equipment and control method as in Example 1, the reacted methyl ethyl ketone (MEK) azide synthesis reaction solution was added to a flash evaporation and concentration device. After concentrating the water content of the MEK azide synthesis reaction solution to 5%, it was then introduced into a tubular reactor. The processing conditions of the tubular reactor were: a processing temperature of 160°C, a processing pressure of 0.8 MPa, and a processing time of 7 min. Samples were taken for analysis after the reaction was completed.

[0095] The recovery rate of the recovered methyl ethyl ketone (MEK) working solution was 88.2% as determined by chromatographic detection.

[0096] The recovered methyl ethyl ketone (MEK) working solution was used to synthesize MEK according to the MEK synthesis method, and the yield of MEK was 91.1%.

[0097] Comparative Example 7

[0098] Using the same equipment and control methods as in Example 1, the reacted methyl ethyl ketone (MEK) azide synthesis reaction solution was added to a flash evaporation and concentration device. After concentrating the water content of the MEK azide synthesis reaction solution to 10%, it was then introduced into a tubular reactor. The processing conditions of the tubular reactor were: a processing temperature of 160°C, a processing pressure of 2 MPa, and a processing time of 7 min. Samples were taken for analysis after the reaction was completed.

[0099] The recovery rate of the recovered methyl ethyl ketone (MEK) working solution was 99.2% as determined by chromatographic detection.

[0100] The methyl ethyl ketone (MEK) working solution was used to synthesize MEK according to the MEK synthesis method, and the yield of MEK was 96.2%.

[0101] Comparative Example 8

[0102] Using the same equipment and control methods as in Example 1, the reacted methyl ethyl ketone (MEK) azide synthesis reaction solution was added to a flash evaporation and concentration device. After concentrating the water content of the MEK azide synthesis reaction solution to 5%, it was then introduced into a tubular reactor. The processing conditions of the tubular reactor were: a processing temperature of 160°C, a processing pressure of 1 MPa, and a processing time of 3 min. Samples were taken for analysis after the reaction was completed.

[0103] The recovery rate of the recovered methyl ethyl ketone (MEK) working solution was 81.3% as determined by chromatographic detection.

[0104] The recovered methyl ethyl ketone (MEK) working solution was used to synthesize MEK according to the MEK synthesis method, and the yield of MEK was 76.3%.

[0105] Comparative Example 9

[0106] Using the same equipment and control methods as in Example 1, the reacted methyl ethyl ketone (MEK) azide synthesis reaction solution was added to a flash evaporation and concentration device. After concentrating the water content of the MEK azide synthesis reaction solution to 5%, it was then introduced into a tubular reactor. The processing conditions of the tubular reactor were: a processing temperature of 160°C, a processing pressure of 1 MPa, and a processing time of 12 min. Samples were taken for analysis after the reaction was completed.

[0107] The recovery rate of the recovered methyl ethyl ketone (MEK) working solution was 97.1% as determined by chromatographic detection.

[0108] The recovered methyl ethyl ketone (MEK) working solution was used to synthesize MEK according to the MEK synthesis method, and the yield of MEK was 94.3%.

[0109] Comparative Example 10

[0110] Using the same equipment and control methods as in Example 1, the reacted methyl ethyl ketone (MEK) azide synthesis reaction solution was added to a flash evaporation and concentration device. After concentrating the water content of the MEK azide synthesis reaction solution to 5%, it was then introduced into a batch reactor. The batch reactor treatment conditions were: treatment temperature set at 160°C, treatment pressure at 1 MPa, and treatment time at 7 min. Samples were taken for analysis after the reaction was completed.

[0111] The recovery rate of the recovered methyl ethyl ketone (MEK) working solution was 48.2% as determined by chromatographic detection.

[0112] The recovered methyl ethyl ketone (MEK) working solution was used to synthesize MEK according to the MEK synthesis method, and the yield of MEK was 56.3%.

[0113] The results were analyzed based on the above embodiments and comparative examples, as shown in Table 1 below:

[0114] Table 1 Experimental conditions and results

[0115]

[0116] As shown in Table 1, before recovering the working solution of methyl ethyl ketone (MEK) using a tubular reactor, a lower water content in the concentrated solution of the MEK synthesis reaction solution is more conducive to improving the recovery rate of the MEK working solution and also to improving the yield of MEK. For example, in Examples 1-10, when the water content of the concentrated solution is between 1% and 10%, the recovery rate of the working solution is above 99%, and the yield of MEK is between 96% and 97.1%. However, when the water content of the concentrated solution is too low, such as in Comparative Example 2, when the water content of the concentrated solution of the MEK synthesis reaction solution is 0.5%, crystal precipitation occurs, making it impossible to conduct subsequent experiments and hindering the synthesis of MEK.

[0117] For tubular reactors, the main influencing factors include the processing temperature, processing pressure, and processing time of the concentrate in the tubular reactor.

[0118] As can be seen from the data in the table, as the processing temperature of the tubular reactor increases, the recovery rate of the working solution and the yield of methyl ethyl ketone (MEK) also increase. However, when the processing temperature exceeds 200℃, the recovery rate of the MEK working solution and the yield of MEK decrease and hardly change anymore.

[0119] Considering the processing pressure and processing time, the recovery rate of the working solution and the yield of methyl ethyl ketone (MEK) were both high when the processing pressure was between 1 MPa and 2 MPa, indicating that this pressure range is suitable for the synthesis of MEK. As shown in Comparative Example 6, the recovery rate of the MEK working solution decreased when the pressure was low, but when the processing pressure was higher than 2 MPa, the recovery rate of MEK no longer changed with the processing pressure.

[0120] When the residence time of the concentrate in the tubular reactor is too short, as in Comparative Example 8 (3 min), the recovery rate of the working solution of methyl ethyl ketone (MEK) is only 81.3%, and the yield of MEK is only 76.3%. This indicates that a short residence time is not conducive to the synthesis of MEK. However, when the residence time of the concentrate in the tubular reactor is too long, as shown in Comparative Example 9, the yield of MEK is 94.3%, and the recovery rate of the working solution of MEK is 97.1%. Compared with the examples with a treatment time of 5-10 min, the yield of MEK and the recovery rate of the working solution of MEK are not significantly improved. This indicates that a treatment time of 5-10 min is sufficient, and extending the treatment time results in a waste of energy.

[0121] Under the same conditions, compared with using a tubular reactor, the recovery rate of methyl ethyl ketone (MEK) working solution was only 48.2% and the yield of MEK was only 56.3% when using a batch reactor to recover MEK working solution, which was significantly lower than that of the tubular reactor. This indicates that the tubular reactor has performance advantages, can significantly reduce the occurrence of side reactions, and improve the yield of the target product.

[0122] The above description is only a preferred embodiment of the present invention. It should be noted that, for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for recovering methyl ethyl ketone (MEK) azohydride working solution, characterized in that: The butanone-azo working solution comprises an amide catalyst, an ammonium acid catalyst, and water; The method for recovering the butanone-azo working solution includes the following steps: S1. Concentration of the methyl ethyl ketone (MEK) azide synthesis reaction solution: The MEK azide synthesis reaction solution is concentrated to obtain a concentrated solution; S2. Recovery of methyl ethyl ketone (MEK) working solution: The concentrate is continuously passed through a tubular reactor to recover the working solution, obtaining MEK and the recovered MEK working solution.

2. The method for recovering the butanone-azohydride working solution according to claim 1, characterized in that: The water content of the concentrate in step S1 is 1-10%.

3. The method for recovering the butanone-azohydride working solution according to claim 2, characterized in that: The water content of the concentrate in step S1 is 1-5%.

4. The method for recovering the butanone-azonium working solution according to any one of claims 1-3, characterized in that: The concentration of the butanone azo synthesis reaction solution in step S1 can be achieved by flash evaporation or distillation.

5. The method for recovering the butanone-azohydride working solution according to claim 1, characterized in that: The processing temperature of the tubular reactor in step S2 is 100-200℃, preferably 130-170℃.

6. The method for recovering the butanone-azohydride working solution according to claim 1, characterized in that: The processing pressure of the tubular reactor in step S2 is 1-2 MPa, preferably 1-1.5 MPa.

7. The method for recovering the butanone-azohydride working solution according to claim 1, characterized in that: In step S2, the residence time of the concentrate in the tubular reactor is 5-10 min, preferably 6-8 min.

8. The method for recovering the butanone-azo working solution according to claim 1, characterized in that: The amide catalyst in the methyl ethyl ketone (MEK) working solution is at least one of formamide, acetamide, propionamide, acrylamide, and butyramide.

9. The method for recovering the butanone-azohydride working solution according to claim 1, characterized in that: The ammonium acid catalyst in the methyl ethyl ketone (MEK) working solution is at least one of ammonium formate, ammonium acetate, ammonium propionate, ammonium acrylate, and ammonium butyrate.

10. The use of a butanone-azo working solution obtained by the recovery method according to any one of claims 1-9 in the preparation of butanone-azo reaction.

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