阅读说明：本技术 一种合成酮肟的方法 (Method for synthesizing ketoxime ) 是由 刘启奎 岳涛 杨旭 卢福军 陈贵军 冯维春 于 2019-09-25 设计创作，主要内容包括：本发明涉及有机合成工艺领域,尤其涉及一种合成酮肟的方法。本发明以酮、氨和双氧水为原料在钛硅分子筛的催化下,在内螺旋管式反应器中制备酮肟。本发明相较于传统制备酮肟的方法首先有利于物料的传质传热,提高了反应效率；平推流和全混流的结合,可以有效减少副反应的发生,提高产物选择性。同时,本发明采用水相反应体系,避免了传统氨肟化工有机溶剂的污染及分离问题。(The invention relates to the field of organic synthesis processes, in particular to a method for synthesizing ketoxime. The ketoxime is prepared in an inner spiral tube type reactor by taking ketone, ammonia and hydrogen peroxide as raw materials under the catalysis of a titanium silicalite molecular sieve. Compared with the traditional method for preparing ketoxime, the method is beneficial to mass transfer and heat transfer of materials, and improves the reaction efficiency; the combination of the plug flow and the complete mixed flow can effectively reduce the occurrence of side reactions and improve the selectivity of products. Meanwhile, the invention adopts a water phase reaction system, thereby avoiding the pollution and separation problems of the traditional organic solvent in the ammoxine chemical industry.)

1. A method for synthesizing ketoxime, characterized by that, adopt the tubular reactor, under 0.1 MPa-0.6 MPa, under the condition of 50-80 duC, enter material A, material B, material C into the tubular reactor separately in three shares and mix and react, finish reacting, quench, discharge;

the material A is ketone and a catalyst; the material B is ammonia gas; the material C is hydrogen peroxide; the feeding sequence is material A, material B and material C in turn.

2. A process for synthesizing a ketoxime according to claim 1 wherein the tubular reactor has an internal helical structure.

3. A process for synthesizing a ketoxime according to claim 1 wherein the ketone has not more than 8 carbon atoms.

4. The method according to claim 1, wherein the pH value of the system is controlled to 9-12 during the reaction.

5. The method for synthesizing ketoxime according to claim 1, wherein the system pressure is adjusted by a back pressure valve during the reaction.

6. The method for synthesizing ketoxime according to claim 1, wherein the residence time of the material A, the material B and the material C in the reactor is 2-15 min.

7. The method according to claim 1, wherein the amount of the catalyst is 1 to 12% by mass based on the ketone.

8. The method for synthesizing ketoxime according to claim 1, wherein the catalyst is a titanium silicalite; the mass fraction of the hydrogen peroxide is 27.5%.

Technical Field

The invention relates to the field of organic synthesis processes, in particular to a method for synthesizing ketoxime.

Background

The traditional ketoxime is prepared by reacting hydroxylamine salt with corresponding ketone, and has the problems of low utilization rate of raw materials, large discharge amount of three wastes, serious environmental pollution and the like. After the TS-1 titanium silicalite molecular sieve is synthesized in a laboratory, cyclohexanone, ammonia and hydrogen peroxide are developed as raw materials, and the titanium silicalite molecular sieve is used for directly synthesizing cyclohexanone oxime. In 2004, the project of 'single-kettle continuous slurry bed synthesis of cyclohexanone oxime package new technology' carried out by the cooperation of China petrochemical science research institute and the Baling division company. The new cyclohexanone ammoximation technology simplifies the production flow, reduces the production cost, has mild reaction conditions and less three-waste discharge, and is a new environment-friendly technology. However, the reaction apparatus has some problems: firstly, the slurry bed reaction kettle has larger volume and poorer mechanical stirring effect, which easily causes the uneven concentration distribution of reactants and generates local hot spots; secondly, the material retention in the reaction kettle is large, and once a large amount of hydrogen peroxide is decomposed, safety accidents can be caused. Patent CN 106380424A mentions that a microreactor is adopted to prepare cyclohexanone oxime, but the reaction is still carried out in an alcohol solvent system, the cyclohexanone oxime needs to be extracted, rectified and purified, the separation process is complex, and the three wastes are large. Patent CN 105152968A mentions the use of a microchannel reactor and synthesis of ketoxime, but the technical scheme still adds a certain proportion of organic solvent, and adopts ammonia water reaction, which increases the occurrence of side reaction and also increases the burden of subsequent separation and purification of ketoxime products. However, due to the very small dimensions of the microreactor channels, agglomeration of the catalyst particles can occur, which often leads to plugging of the microreactor channels.

In summary, the ammoximation process has the following problems: (1) the problem of difficult gas-liquid-solid heterogeneous mass and heat transfer exists in the solvent-free oximation reaction; (2) further deep oxidation of oxime exists in the oximation process, more side reactions occur in series, nitroalkane byproducts exist, and the product selectivity is poor.

Disclosure of Invention

In order to overcome the defects of the traditional ketoxime preparation process, the invention provides a method for synthesizing ketoxime, which strengthens mass transfer and heat transfer through an internal spiral tubular reactor, has short retention time and improves the reaction speed and the utilization rate of materials. Ketoxime is prepared in an inner spiral tube type reactor by taking ketone, ammonia and hydrogen peroxide as raw materials under the catalysis of a titanium silicalite molecular sieve. Compared with the traditional method for preparing ketoxime, the method is beneficial to mass transfer and heat transfer of materials, and improves the reaction efficiency; the combination of the plug flow and the complete mixed flow can effectively reduce the occurrence of side reactions and improve the selectivity of products. Meanwhile, the invention adopts a water phase reaction system, thereby avoiding the pollution and separation problems of the traditional organic solvent in the ammoxine chemical industry.

The method for synthesizing ketoxime adopts a tubular reactor, under the conditions of 0.1-0.6 MPa and 50-80 ℃, a material A, a material B and a material C are respectively fed into the tubular reactor in three strands for mixing and reaction, and after the reaction is finished, quenching and discharging are carried out;

the material A is ketone and a catalyst; the material B is ammonia gas; the material C is hydrogen peroxide; the feeding sequence is material A, material B and material C in turn. The reaction process is controlled by detecting the pH value in the reaction process, and the content is analyzed to compare the oximation effect after the reaction is finished.

According to the analysis of the reaction, the reaction system needs to keep a certain pH value, so that ammonia gas needs to enter before hydrogen peroxide, the ammonia gas and the hydrogen peroxide need to continuously react with ketone to generate oxime after reacting to generate hydroxylamine, and the generated hydroxylamine can react with newly-entered hydrogen peroxide to generate waste salt if the generated hydroxylamine cannot react with the ketone in time.

The tubular reactor is matched with a back pressure valve and a temperature control system. The tubular reactor is a tubular reactor with an internal spiral structure, and the model is RHB 1006.

The ketone includes, but is not limited to acetone, butanone, cyclohexanone and other ketones with carbon number not more than 8.

In the reaction process, the pH value of the system is controlled to be 9-12. The pH value of the system is controlled by controlling the feeding speed of ammonia gas and hydrogen peroxide. The pH value is controlled to be 9-12, a certain ammonia concentration of the system needs to be maintained, if the pH value is lower, side reactions are more, and a certain amount of nitro impurities and waste salts are generated under the condition that hydrogen peroxide is relatively more; if the pH value is higher, the catalyst is damaged, and the catalyst is a titanium silicalite molecular sieve, so that the framework is dissolved, and the service life of the catalyst is greatly shortened. The certain pH value of the system is maintained, the utilization rate of hydrogen peroxide can be improved, and the ineffective decomposition and side reaction of materials are reduced.

In the reaction process, the system pressure is 0.1 MPa-0.6 MPa, and the system pressure is adjusted by a back pressure valve.

And the residence time of the material A, the material B and the material C in the reactor is 2-15 min.

The catalyst is a titanium silicalite molecular sieve, and the dosage of the catalyst is 1-12% of the mass of the ketone. In the invention, TS-1 is preferably selected as the catalyst, 27.5% is preferably selected as the mass fraction of hydrogen peroxide, too low mass fraction affects the contact of reactants, and too high mass fraction increases the unsafety of the reaction.

According to the experimental research of the inventor, the titanium silicalite molecular sieve is hydrophobic and oleophilic, so that in the intermittent reaction process of a reaction bottle, the mechanical stirring effect is poor, the catalyst is not uniformly dispersed, the mass and heat transfer problems of materials occur, the ineffective decomposition of the materials is more, and the reaction effect is poor; batch reactions are fed continuously, without production, and there will be further oxidation of the reaction product, with the main byproduct being nitroalkane. The micro-reactor has the problems of easy blockage of the catalyst and troublesome cleaning.

To avoid the above problems, 1) pure heat transfer during the reaction needs to be enhanced, and the reaction process needs to be strengthened; 2) reaction products are extracted from a reaction system in time, and the occurrence of serial side reactions is avoided; 3) avoiding the blockage of the reaction channel.

Aiming at the characteristic of the reaction with serial side reactions, the invention selects the spiral tube type reactor, adopts a spiral propulsion mode and combines plug flow with complete mixed flow mode, solves the problems of more side reactions and poor mixing effect of the plug flow propulsion reaction mode in the traditional kettle type reaction, achieves the aim of reducing the side reactions while increasing the reaction mixing effect, strengthens the mass and heat transfer, has uniform material distribution and improved reaction rate, and has the ketone conversion rate of more than 98 percent.

The pH value is controlled within the range of 9-12, and the reaction process is judged by a method of monitoring the pH value in the reaction system on line, so that the optimal reaction ratio is determined, and the conversion rate of the reaction is further ensured.

The water in the hydrogen peroxide can be directly used as a reaction solvent to fully mix reaction materials. The invention utilizes the strong hydrogen bond characteristic of water and the bonding characteristic of the water to reactant molecules and the catalyst, promotes the heterogeneous reaction by regulating and controlling the regulation and control site of the catalyst and the carrier interface, solves the problems of environmental pollution, low safety coefficient and large separation difficulty caused by organic solvents in the traditional process, reduces the production cost and improves the reaction safety.

The internal spiral tubular reactor adopts simultaneous continuous feeding and continuous discharging, realizes the continuity of the reaction, avoids the occurrence of side reaction, and has the selectivity of the product more than 99 percent. The reaction channel of the internal spiral tubular reactor has larger size and specific surface area and is not easy to block.

Drawings

FIG. 1 is a flow diagram of a specific reaction according to the present invention.

Detailed Description

For better understanding of the present invention, the technical solution of the present invention will be described in detail with specific examples, but the present invention is not limited thereto.