阅读说明：本技术 一种提高环己酮肟质量和收率的生产工艺及设备系统 (Production process and equipment system for improving quality and yield of cyclohexanone-oxime ) 是由 肖藻生 肖有昌 师太平 于 2019-12-04 设计创作，主要内容包括：一种提高环己酮肟质量和收率的生产工艺以及设备系统。本发明生产工艺采用特定的直接氨肟化的反应条件,结合二次肟化反应,在不提高双氧水消耗量前提下,有效提高环己酮的肟化转化率,进而提高了环己酮肟收率和质量。本发明设备系统,包括依次通过管线连通的直接氨肟化反应器、膜分离器、有机溶剂萃取塔和二次肟化反应器。本发明生产工艺以及设备系统结构简单,操作运行安全,能够高收率的制备高质量环己酮肟。(A production process and a device system for improving the quality and the yield of cyclohexanone-oxime. The production process of the invention adopts specific reaction conditions of direct ammoximation and combines secondary oximation reaction, thereby effectively improving the oximation conversion rate of cyclohexanone without increasing the consumption of hydrogen peroxide and further improving the yield and quality of cyclohexanone oxime. The equipment system comprises a direct ammoximation reactor, a membrane separator, an organic solvent extraction tower and a secondary oximation reactor which are sequentially communicated through pipelines. The production process and the equipment system have simple structure and safe operation, and can prepare high-quality cyclohexanone oxime with high yield.)

1. A production process for improving the quality and yield of cyclohexanone-oxime is characterized by comprising the following steps:

(1) taking ammonia, hydrogen peroxide and cyclohexanone as raw materials, taking a titanium silicalite molecular sieve as a catalyst, taking water or a tert-butyl alcohol/water mixed solution as a solvent, carrying out a primary oximation reaction, controlling the conversion rate of the cyclohexanone to 97-99%, recovering the catalyst, and extracting a reaction solution by using an organic solvent to obtain an extract liquid containing cyclohexanone oxime, wherein the molar ratio of the cyclohexanone to the ammonia to the hydrogen peroxide is 1: 1.2-1.5: 1-1.02;

(2) adding a hydroxylamine sulfate aqueous solution into the cyclohexanone oxime-containing extract liquid obtained in the step (1), carrying out a secondary oximation reaction, adopting ammonia to control the secondary oximation reaction to be carried out under the condition that the pH value is 5-7 all the time, separating to obtain an organic phase containing cyclohexanone oxime after the reaction is finished, washing with water, and concentrating to obtain the cyclohexanone oxime.

2. The production process for improving the quality and yield of cyclohexanone oxime according to claim 1, wherein in step (2), the aqueous solution of hydroxylamine sulfate is prepared by dissolving solid hydroxylamine sulfate, or is prepared by mixing the organic phase of part of cyclohexanone oxime obtained in step (1) with sulfuric acid, or is prepared by mixing part of cyclohexanone oxime obtained in step (2) with sulfuric acid; preferably, in the step (2), the temperature of the secondary oximation reaction is 50 +/-20 ℃, and the pressure is 0.2-0.4 MPa; in the secondary oximation reaction, the initial concentration of the hydroxylamine sulfate aqueous solution at the inlet is 2.0 +/-0.2 mol/L, and the concentration at the outlet is 0.2 +/-0.05 mol/L.

3. The production process for improving the quality and yield of cyclohexanone oxime according to claim 1 or 2, wherein in the step (1), the primary oximation reaction is carried out by using water as a solvent, the temperature of the primary oximation reaction is 86-94 ℃, and the pressure is 0.2-0.4 MPa; preferably, the solvent used for the extraction is selected from one or more of methylcyclohexane, cyclohexane and hexane; preferably, the volume ratio of the solvent used for extraction to the reaction solution is 1: 2-5.

4. The production process for improving the quality and yield of cyclohexanone oxime according to claim 1 or 2, wherein in the step (1), the primary oximation reaction is performed by using a tert-butyl alcohol/water mixed solution as a solvent, the temperature of the primary oximation reaction is 80-86 ℃, and the pressure is 0.2-0.4 MPa; preferably, in the step (1), before the extraction, the reaction clear liquid is subjected to a tert-butyl alcohol recovery step, wherein the tert-butyl alcohol recovery step is to recover tert-butyl alcohol by rectifying the reaction clear liquid to obtain a rectifying still liquid to be extracted, and the recovered tert-butyl alcohol is returned to be used as a solvent for the primary oximation reaction; preferably, the solvent used for the extraction is toluene.

5. An equipment system for improving quality and yield of cyclohexanone oxime, which is characterized by comprising: the device comprises a direct ammoximation reactor, a membrane separator, an organic solvent extraction tower and a secondary oximation reactor which are connected in sequence through pipelines.

6. The equipment system for improving the quality and the yield of cyclohexanone oxime according to claim 5, wherein the direct ammoximation reactor is connected with a reaction liquid pipeline and is connected with a membrane separator through the reaction liquid pipeline; a catalyst circulating pipeline and a reaction clear liquid pipeline are connected out of the membrane separator, the membrane separator is connected with the direct ammoximation reactor through the catalyst circulating pipeline, the membrane separator is connected with the organic solvent extraction tower through the reaction clear liquid pipeline, and a reaction material pipeline is connected to the catalyst circulating pipeline; the organic solvent extraction tower is connected with an organic solvent pipeline, connected with a tower top pipeline and a tower kettle pipeline, connected with the secondary oximation reactor through the tower top pipeline and connected with the direct ammoximation reactor through the tower kettle pipeline; the secondary oximation reactor is connected with a hydroxylamine sulfate pipeline and an ammonia pipeline, a cyclohexanone oxime solution pipeline and a water phase discharge pipeline are connected, and the cyclohexanone oxime solution pipeline is connected out of the equipment system.

7. The equipment system for improving the quality and the yield of cyclohexanone oxime according to claim 5, wherein a tert-butyl alcohol recovery tower is arranged between the membrane separator and the organic solvent extraction tower, and a toluene recovery tower is arranged behind the secondary oximation reactor; the direct ammoximation reactor is connected with a reaction liquid pipeline and is connected with a membrane separator through the reaction liquid pipeline; a catalyst circulation pipeline and a reaction clear liquid pipeline are connected out of the membrane separator, the membrane separator is connected with the direct ammoximation reactor through the catalyst circulation pipeline, the membrane separator is connected with a tertiary butanol recovery tower through the reaction clear liquid pipeline, and a reaction material pipeline is connected to the catalyst circulation pipeline; a tertiary butanol recovery pipeline and a water phase reaction liquid pipeline are connected out of the tertiary butanol recovery tower, connected with the direct oximation reactor through the tertiary butanol recovery pipeline, and connected with the organic solvent extraction tower through the water phase reaction liquid pipeline; the organic solvent extraction tower is connected with a tower top pipeline and a tower kettle pipeline, is connected with the secondary oximation reactor through the tower top pipeline, and is connected with the direct ammoximation reactor through the tower kettle pipeline; the secondary oximation reactor is connected with a hydroxylamine sulfate pipeline and an ammonia pipeline, connected with a cyclohexanone oxime solution pipeline and a water phase discharge pipeline, and connected with a toluene recovery tower through the cyclohexanone oxime solution pipeline; the toluene recovery tower is connected with an organic solvent pipeline and the cyclohexanone oxime pipeline, and is connected with the organic solvent extraction tower through the organic solvent pipeline, and the cyclohexanone oxime pipeline is connected with the equipment system.

8. The equipment system for improving the quality and the yield of cyclohexanone oxime according to claim 6 or 7, wherein the equipment system further comprises a hydroxylamine sulfate configuration tank, the hydroxylamine sulfate configuration tank is provided with a process water pipeline and a hydroxylamine sulfate solid feeding port, and is connected with a secondary oximation reactor through the hydroxylamine sulfate pipeline; preferably, the secondary oximation reactor is a packed tower type reverse flow reactor or a kettle type reactor; preferably, the secondary oximation reactor is a kettle-type reactor, and is connected with a sedimentation separator, the secondary oximation reactor is only connected with a secondary oximation reaction liquid pipeline, the secondary oximation reaction liquid pipeline is connected with the sedimentation separator, the sedimentation separator is connected with a cyclohexanone oxime solution pipeline and a hydroxylamine sulfate circulation pipeline, the hydroxylamine sulfate circulation pipeline is connected with the secondary oximation reactor, and a water phase discharge pipeline is connected to the hydroxylamine sulfate circulation pipeline; preferably, the direct ammoximation reactor is provided with a tail gas discharge pipeline; preferably, the catalyst recycling line is connected with a catalyst recycling line.

9. The equipment system for improving the quality and the yield of cyclohexanone oxime according to claim 6, wherein the equipment system further comprises an oxime hydrolysis reactor, an oxime hydrolysis catalyst separator and a hydroxylamine sulfate separator, wherein the oxime hydrolysis reactor is connected with a sulfuric acid pipeline, the tower top pipeline and an oxime hydrolysis catalyst pipeline, is connected with an oxime hydrolysis reaction liquid pipeline, is connected with the organic solvent extraction tower through the tower top pipeline, and is connected with the oxime hydrolysis catalyst separator through the oxime hydrolysis reaction liquid pipeline; the oxime hydrolysis catalyst separator is connected with an oxime hydrolysis catalyst circulating pipeline and an oxime hydrolysis reaction clear liquid pipeline, is connected with the oxime hydrolysis reactor through the oxime hydrolysis catalyst circulating pipeline, and is connected with the hydroxylamine sulfate separator through the oxime hydrolysis reaction clear liquid pipeline; the hydroxylamine sulfate separator is connected with the hydroxylamine sulfate pipeline and the cyclohexanone recovery pipeline and is connected with the secondary oximation reactor through the hydroxylamine sulfate pipeline; preferably, the secondary oximation reactor is a packed tower type reverse flow reactor or a kettle type reactor; preferably, the secondary oximation reactor is a kettle-type reactor, and is connected with a sedimentation separator, the secondary oximation reactor is only connected with a secondary oximation reaction liquid pipeline, the secondary oximation reaction liquid pipeline is connected with the sedimentation separator, the sedimentation separator is connected with a cyclohexanone oxime solution pipeline and a hydroxylamine sulfate circulation pipeline, the hydroxylamine sulfate circulation pipeline is connected with the secondary oximation reactor, and a water phase discharge pipeline is connected to the hydroxylamine sulfate circulation pipeline; preferably, the direct ammoximation reactor is provided with a tail gas discharge pipeline; preferably, the catalyst circulation line is connected with a catalyst recovery line, preferably, the oxime hydrolysis catalyst circulation line is connected with an oxime hydrolysis catalyst line, and preferably, the oxime hydrolysis catalyst circulation line is connected with an oxime hydrolysis catalyst recovery line.

10. The equipment system for improving the quality and the yield of cyclohexanone oxime according to claim 7, wherein the equipment system further comprises an oxime hydrolysis reactor, an oxime hydrolysis catalyst separator and a hydroxylamine sulfate separator, wherein the oxime hydrolysis reactor is connected with a sulfuric acid pipeline, the cyclohexanone oxime pipeline and an oxime hydrolysis catalyst pipeline, is connected with an oxime hydrolysis reaction liquid pipeline, and is connected with the oxime hydrolysis catalyst separator through the oxime hydrolysis reaction liquid pipeline; the oxime hydrolysis catalyst separator is connected with an oxime hydrolysis catalyst circulating pipeline and an oxime hydrolysis reaction clear liquid pipeline, is connected with the oxime hydrolysis reactor through the oxime hydrolysis catalyst circulating pipeline, and is connected with the hydroxylamine sulfate separator through the oxime hydrolysis reaction clear liquid pipeline; the hydroxylamine sulfate separator is connected with a cyclohexanone recovery pipeline and a hydroxylamine sulfate pipeline, and is connected with the secondary oximation reactor through the hydroxylamine sulfate pipeline; preferably, the secondary oximation reactor is a packed tower type reverse flow reactor or a kettle type reactor; preferably, the secondary oximation reactor is a kettle-type reactor, and a sedimentation separator is connected behind the kettle-type reactor, the secondary oximation reactor is only connected with a secondary oximation reaction liquid pipeline, the secondary oximation reaction liquid pipeline is connected with the sedimentation separator, the sedimentation separator is connected with a cyclohexanone oxime solution pipeline and a hydroxylamine sulfate circulation pipeline, the hydroxylamine sulfate circulation pipeline is connected with the secondary oximation reactor, and a water phase discharge pipeline is connected to the hydroxylamine sulfate circulation pipeline; preferably, the direct ammoximation reactor is provided with a tail gas discharge pipeline; preferably, the catalyst circulation line is connected with a catalyst recovery line, preferably, the oxime hydrolysis catalyst circulation line is connected with an oxime hydrolysis catalyst line, and preferably, the oxime hydrolysis catalyst circulation line is connected with an oxime hydrolysis catalyst recovery line.

Technical Field

The invention belongs to the field of cyclohexanone oxime preparation, and particularly relates to a production process and an equipment system for improving the quality and yield of cyclohexanone oxime.

Background

Currently, caprolactam is mainly prepared from cyclohexanone oxime by beckmann rearrangement and transposition, and the main processes for preparing cyclohexanone oxime are raschig method (hydroxylamine sulfate method), HPO method (hydroxylamine phosphate method), NO reduction method, and direct ammoximation method. The Raschig method adopts cyclohexanone and hydroxylamine sulfate to carry out oximation reaction to obtain cyclohexanone oxime. The hydroxylamine sulfate is prepared by reducing ammonium nitrite with sulfur dioxide, the process is very mature and is the earliest successful process route, but because the by-product ammonium sulfate is more, the quality of the obtained hydroxylamine sulfate is general, and therefore, the raschig method is less adopted by newly-built devices at present. Although the NO reduction method also adopts the reaction of hydroxylamine sulfate and cyclohexanone to generate cyclohexanone oxime, the hydroxylamine sulfate is obtained by reducing NO by using hydrogen under the condition of a catalyst, the by-product ammonium sulfate is less than that of the Raschig method, the quality of the hydroxylamine sulfate is good, the oximation conversion rate of the cyclohexanone reaches over 99.98 percent, namely the oximation conversion rate of the cyclohexanone is close to 100 percent, high-quality cyclohexanone oxime is obtained, and then high-quality caprolactam is obtained by Beckmann rearrangement and transposition. Therefore, the NO reduction method is adopted, so that the subsequent caprolactam purification process is very simple and efficient. There are also plants which employ this process to produce caprolactam of high quality.

The preparation of cyclohexanone oxime by Hydroxylamine Phosphate (HPO) method is characterized by that cyclohexanone and hydroxylamine phosphate are undergone the oximation reaction under the acidic condition, and the countercurrent extraction by using toluene can be used for accelerating the oximation reaction to a certain extent, and making equilibrium reaction be favorable for producing cyclohexanone oxime, and at the same time adopting pulse oximation tower and excess hydroxylamine phosphate condition to promote oximation reaction. However, the phosphoric acid mother liquor needs to be recycled, after extraction and stripping, the phosphoric acid mother liquor still contains about 100ppm of organic impurities such as cyclohexanone oxime, and then nitrogen oxide gas is absorbed by the phosphoric acid mother liquor to generate a mixed solution of phosphoric acid, nitric acid and nitrous acid, and cyclohexanone oxime in the organic matters is inevitably decomposed under acidic conditions to generate cyclohexanone and hydroxylamine and is oxidized into cyclohexanone deeply oxidized impurities by nitric acid. Since the flow rate of the phosphoric acid mother liquor is 10 times of that of cyclohexanone oxime, the cyclohexanone oxime produced by the hydroxylamine phosphate (HPO method) process contains 1000ppm to 2000ppm of organic impurities, so that processes such as ion exchange or aqueous solution hydrogenation are required to purify the generated caprolactam, and the quality of the produced caprolactam is not as good as that of the NO reduction method of BASF. It can be seen that the quality problem of cyclohexanone oxime is the key core in determining the quality of the final caprolactam, regardless of how the subsequent caprolactam purification process is enhanced. And the problem of solving the quality problem of cyclohexanone oxime is mainly the problem of improving the oximation conversion rate of cyclohexanone.

Compared with other three processes, caprolactam produced by a direct ammoximation method has the simplest flow and the least ammonium sulfate byproduct, but still has the problems of poor product quality and high unit consumption of cyclohexanone (low cyclohexanone oximation conversion rate).

The traditional direct ammoximation of cyclohexanone takes ammonia, hydrogen peroxide and cyclohexanone as raw materials, takes a titanium silicalite molecular sieve as a catalyst and takes a tertiary butanol aqueous solution as a solvent. The reaction mechanism is believed to be primarily a hydroxylamine mechanism: in the reaction process, small molecular ammonia and hydrogen peroxide are diffused into a pore channel of the titanium-silicon molecular sieve, and the ammonia is oxidized by the hydrogen peroxide in the pore channel of the titanium-silicon molecular sieve to generate hydroxylamine; because the silicon dioxide in the molecular sieve is weakly acidic, hydroxylamine is relatively stable in a titanium-silicon molecular sieve pore channel, and the hydroxylamine is diffused to the surface of the titanium-silicon molecular sieve to generate cyclohexanone oxime with cyclohexanone in the tert-butyl alcohol aqueous solution. The documents of CN103382163A, CN204079842U, CN101781232A and the like all think that the cyclohexanone oximation conversion rate of the direct ammoximation reaction can reach more than 99.5 percent.

CN105837468B and WO/2016/112814 respectively disclose a direct ammoximation process without tert-butyl alcohol, wherein the process replaces the tert-butyl alcohol with water and directly adopts three heterogeneous phase systems of a cyclohexanone organic phase, a water phase and a catalyst solid phase. Although this process reduces the steam consumption required for the recovery of tert-butanol, it is known from the literature that the conversion of oximation of cyclohexanone in one step is reported to exceed 99.9%, in practice, the unit consumption of cyclohexanone and the quality of cyclohexanone oxime are not improved.

When the invention adopts the process for preparation, the inventor discovers that under the conditions that hydrogen peroxide is 8% -14% excessive and ammonia is 10-20% excessive, detailed chromatographic analysis and mass spectrometric analysis are carried out on the reaction liquid, and a certain amount of cyclohexylimine (a reaction intermediate of cyclohexanone and ammonia) is found to exist in the reaction liquid, the retention time of the cyclohexylimine in the chromatogram is different from that of the cyclohexanone, so that the cyclohexylimine can be possibly attributed to reaction impurities, and a part of cyclohexylimine is decomposed or condensed under the high-temperature condition of gas chromatography and can not be accurately and quantitatively detected. In fact, cyclohexylimine can be converted into cyclohexanone in the reaction solution, and can be continuously oximated with hydroxylamine to form cyclohexanone oxime, and therefore, when calculating the conversion of cyclohexanone, it should be considered as an equivalent of cyclohexanone. Compared with the method for converting cyclohexanone in the traditional cyclohexanone direct ammoximation process of the following formula (1), if cyclohexylimine is considered, the oximation conversion rate of cyclohexanone calculated according to the formula (2) is only 98-99%, which is also the reason that the unit consumption of cyclohexanone in the traditional cyclohexanone direct ammoximation method is high.

Subsequent analysis shows that the cyclohexanone and the cyclohexylimine which are not oximated are subjected to membrane separation along with the cyclohexanone oxime, are heated, dehydrated and polymerized in the process of rectifying and recovering the tertiary butanol, generate schiff base substances such as an imine polymer and the like, and enter the toluene for extraction along with the cyclohexanone oxime. Extracting unreacted cyclohexanone, cyclohexylimine and cyclohexanone oxime to enter a toluene solution, rectifying the toluene solution containing cyclohexanone oxime, cyclohexanone and cyclohexylimine after washing, and generating impurities such as dimeric imine, octahydrophenazine and the like from the alkaline mixed toluene solution of cyclohexanone oxime, cyclohexylimine and cyclohexanone under the high-temperature condition of rectification. Toluene, cyclohexanone and cyclohexylimine are recovered from the top of the tower, cyclohexanone oxime (with the purity of 99-99.5%) containing impurities such as dimeric cyclohexylimine and octahydrophenazine is discharged from the bottom of the tower, and then enters a Beckmann rearrangement transposition process, so that the volatile alkali index of a subsequent caprolactam product is unqualified. Therefore, the conversion rate of cyclohexanone in the traditional direct ammoximation process is low, which results in high unit consumption of cyclohexanone, and substances such as polycyclohexylimine and octahydrophenazine generated in the rectification process result in poor quality of cyclohexanone oxime due to the conversion of cyclohexanone into cyclohexylimine, so that the quality of caprolactam cannot reach the international first-class level. The amount of hydrogen peroxide and ammonia in the oximation reaction is increased, although the problem can be alleviated to a certain extent, the excessive hydrogen peroxide is unstable, ammonia can be oxidized into nitrogen oxide, the environment is further polluted, the safety risk of industrial implementation is greatly improved, and the method is not in accordance with the current direction of developing green and safe chemical engineering in China.

CN101781232A discloses a cyclohexanone oxime preparation process, which combines two oximation reactions, for solving the problem of incomplete conversion rate of direct ammoximation of cyclohexanone by cyclohexanone in one step, but they firstly also consider that the conversion rate of oximation in one step can reach or exceed 99.5%, and do not recognize that the conversion rate of oximation of cyclohexanone is actually lower due to the existence of cyclohexylimine. In addition, in the second oximation reaction, although an excessive hydroxylamine sulfate aqueous solution is adopted, the pH is not adjusted simultaneously in the reaction process, so that the concentration of hydroxylamine salt is high in the reaction system, but the concentration of free hydroxylamine actually participating in the oximation reaction is not high, and in addition, sulfuric acid by-product of the oximation reaction is not neutralized in time, so that the system is more and more acidic. Experiments prove that under the strong acid condition, the method cannot increase the oximation conversion rate of cyclohexanone, but cyclohexanone oxime may be lost, so that the secondary oximation of the process cannot improve the total oximation conversion rate of cyclohexanone, and the patent is still in an unapplied stage.

Disclosure of Invention

The invention aims to solve the technical problem of overcoming the defects and providing a production process and a production equipment system for improving the quality and the yield of the cyclohexanone-oxime. The production process effectively improves the oximation conversion rate of the cyclohexanone without improving the consumption of the hydrogen peroxide, thereby improving the yield and the quality of the cyclohexanone oxime. The equipment system has simple structure and safe operation, and can prepare high-quality cyclohexanone oxime with high yield.

The technical scheme adopted by the invention for solving the technical problems is as follows:

a production process for improving the quality and yield of cyclohexanone-oxime comprises the following steps:

(1) taking ammonia, hydrogen peroxide and cyclohexanone as raw materials, taking a titanium silicalite molecular sieve as a catalyst, taking water or a tert-butyl alcohol/water mixed solution as a solvent, carrying out a primary oximation reaction, controlling the conversion rate of the cyclohexanone to 97-99%, recovering the catalyst, and extracting a reaction solution by using an organic solvent to obtain an extract liquid containing cyclohexanone oxime, wherein the reaction molar ratio of the cyclohexanone to the ammonia to the hydrogen peroxide is 1: 1.2-1.5: 1-1.02;

(2) adding a hydroxylamine sulfate aqueous solution into the extract containing cyclohexanone oxime to perform a secondary oximation reaction, adopting ammonia to control the secondary oximation reaction to be performed under the condition that the pH value is 5-7 all the time, separating to obtain an organic phase containing cyclohexanone oxime after the reaction is finished, washing with water, and concentrating to obtain the cyclohexanone oxime.

The preparation method is obtained through long-term research. The inventor finds that the oximation conversion rate of the direct ammoximation process is not ideal, and through analysis and research on a test field, the main reason is that cyclohexanone and ammonia are combined to form cyclohexylimine, so that the yield and the quality of cyclohexanone oxime are low. In combination with the hydroxylamine reaction mechanism of the conventional direct ammoximation reaction, the reaction process does not consider the generation of cyclohexylimine, so the inventors have proposed a new mechanism based on the aforementioned research, specifically shown in formulas (3) to (8):

the reaction mechanism is mainly that an imine mechanism and a traditional hydroxylamine mechanism are combined into one: extracting cyclohexanone into a water phase, and reacting with ammonia water to generate a cyclohexyl imine hydrate and cyclohexyl imine thereof, wherein the cyclohexyl imine hydrate and the cyclohexyl imine are shown as a formula (3) and a formula (4); meanwhile, hydrogen peroxide is adsorbed by Ti of the titanium-silicon molecular sieve and oxidizes the Ti into a peroxy state for transitionThe valence of metal Ti is changed, the energy of oxidation reduction is reduced, atomic oxygen is released, and ammonia adsorbed on the active center of Si is oxidized to form NH₂OH; high concentration of ammonia, stronger basicity than hydroxylamine, NH₃Continuous replacement of NH from Si active centers₂OH, diffusing it to the surface of the catalyst to obtain [ NH ]₃OH]HSiO₃As shown in formula (5); the hydrates of cyclohexylimine and its cyclohexylimine are alkaline, are more easily adsorbed to the surface of catalyst than cyclohexanone, and can be combined with [ NH ] on the surface of catalyst₃OH]HSiO₃And (4) carrying out a displacement reaction to generate more stable cyclohexanone oxime as shown in a formula (6-8).

On the basis of the mechanism, the inventor analyzes that the amount of the hydrogen peroxide is increased under the condition that the concentration of the catalyst is kept to be certain, although the concentration of the hydroxylamine on the surface of the catalyst can be increased to a certain extent so as to improve the oximation conversion rate of the cyclohexanone, the hydroxylamine is unstable under the strong alkaline environment with excessive ammonia, and can be continuously oxidized by the hydrogen peroxide or directly decomposed to generate a large amount of nitrogen oxide, the concentration of the hydroxylamine on the surface of the catalyst can reach an equilibrium value, and the proportion of the hydroxylamine cannot be increased due to the increase of the hydrogen peroxide, so that the hydroxylamine cannot be greatly excessive in the method under the condition of consuming a large amount of hydrogen peroxide, and the conversion rate of the cyclohexanone oxime cannot be improved to more than 99.5 percent expected. Therefore, the cyclohexanone and hydrogen peroxide are subjected to proportional reaction in step (1), or the hydrogen peroxide is slightly excessive, the cyclohexanone oximation conversion rate is controlled to be 97-99%, and the cyclohexanone is oximated as much as possible on the premise of reducing hydrogen peroxide consumption and nitrogen oxide waste gas; then, the cyclohexanone and cyclohexylimine which are not completely reacted in the reaction solution are subjected to the step (2), and the conversion rate of the cyclohexanone oxime is increased to more than the expected 99.98% under the condition that the hydroxylamine is greatly excessive.

The hydroxylamine sulfate aqueous solution in the step (2) can be prepared by dissolving hydroxylamine sulfate solid water, and can also be prepared by other ketoxime acidic hydrolysis processes. Preferably, in the step (2), the hydroxylamine sulfate solution is prepared from the organic phase of part of cyclohexanone oxime obtained in the step (1) and sulfuric acid, or is prepared from part of cyclohexanone oxime obtained in the step (2) and sulfuric acid. Therefore, the purchase cost of new raw materials is avoided, new ketone ammoximation equipment is not required to be added, and the risk of new impurities brought into the system by the raw materials is reduced.

Preferably, in the step (1), water is used as a solvent in the primary oximation reaction, the temperature of the primary oximation reaction is 86-94 ℃, and the pressure is 0.2-0.4 MPa.

Preferably, in the step (1), the solvent used for the extraction is one or more selected from the group consisting of methylcyclohexane, cyclohexane and hexane.

Preferably, in the step (1), the volume ratio of the solvent used for extraction to the reaction solution is 1: 2-5.

Preferably, in the step (1), the recovered catalyst is separated from the reaction clear solution by membrane separation, and then the catalyst is recovered.

Preferably, in the step (1), the primary oximation reaction uses a tert-butyl alcohol/water mixed solution as a solvent, and the temperature of the primary oximation reaction is 80-86 ℃ and the pressure is 0.2-0.4 MPa.

Preferably, in the step (1), before the extraction, the reaction clear liquid is subjected to a tert-butyl alcohol recovery step, wherein the tert-butyl alcohol recovery step is to recover tert-butyl alcohol by rectifying the reaction clear liquid to obtain a rectifying still liquid to be extracted, and the recovered tert-butyl alcohol is returned to be used as a solvent for the primary oximation reaction.

Preferably, in the step (2), the temperature of the second oximation reaction is 30-70 ℃, and the pressure is 0.2-0.4 MPa.

Preferably, in the step (2), in the secondary oximation reaction, the initial concentration of the hydroxylamine sulfate aqueous solution at the inlet is 2.0 +/-0.2 mol/L, and the concentration at the outlet is 0.2 +/-0.05 mol/L.

The equipment system for improving the quality and the yield of the cyclohexanone-oxime comprises a direct ammoximation reactor, a membrane separator, an organic solvent extraction tower and a secondary oximation reactor which are sequentially communicated through pipelines.

Preferably, the direct ammoximation reactor is connected with a reaction liquid pipeline and is connected with a membrane separator through the reaction liquid pipeline; a catalyst circulating pipeline and a reaction clear liquid pipeline are connected out of the membrane separator, the membrane separator is connected with the direct ammoximation reactor through the catalyst circulating pipeline, the membrane separator is connected with the organic solvent extraction tower through the reaction clear liquid pipeline, and a reaction material pipeline is connected to the catalyst circulating pipeline; the organic solvent extraction tower is connected with an organic solvent pipeline, connected with a tower top pipeline and a tower kettle pipeline, connected with the secondary oximation reactor through the tower top pipeline and connected with the direct ammoximation reactor through the tower kettle pipeline; the secondary oximation reactor is connected with a hydroxylamine sulfate pipeline and an ammonia pipeline, a cyclohexanone oxime solution pipeline and a water phase discharge pipeline are connected, and the cyclohexanone oxime solution pipeline is connected out of the equipment system.

Preferably, a tert-butyl alcohol recovery tower is arranged between the membrane separator and the organic solvent extraction tower, and a toluene recovery tower is arranged behind the secondary oximation reactor; the direct ammoximation reactor is connected with a reaction liquid pipeline and is connected with a membrane separator through the reaction liquid pipeline; a catalyst circulation pipeline and a reaction clear liquid pipeline are connected out of the membrane separator, the membrane separator is connected with the direct ammoximation reactor through the catalyst circulation pipeline, the membrane separator is connected with a tertiary butanol recovery tower through the reaction clear liquid pipeline, and a reaction material pipeline is connected to the catalyst circulation pipeline; a tertiary butanol recovery pipeline and a water phase reaction liquid pipeline are connected out of the tertiary butanol recovery tower, connected with the direct oximation reactor through the tertiary butanol recovery pipeline, and connected with the organic solvent extraction tower through the water phase reaction liquid pipeline; the organic solvent extraction tower is connected with a tower top pipeline and a tower kettle pipeline, and is connected with the secondary oximation reactor through the tower top pipeline, and the tower kettle pipeline is connected with the direct ammoximation reactor; the secondary oximation reactor is connected with a hydroxylamine sulfate pipeline and an ammonia pipeline, connected with a cyclohexanone oxime solution pipeline and a water phase discharge pipeline, and connected with a toluene recovery tower through the cyclohexanone oxime solution pipeline; the toluene recovery tower is connected with an organic solvent pipeline and the cyclohexanone oxime pipeline, and is connected with the organic solvent extraction tower through the organic solvent pipeline, and the cyclohexanone oxime pipeline is connected with the equipment system.

Preferably, the equipment system further comprises a hydroxylamine sulfate configuration tank, wherein a process water pipeline and a hydroxylamine sulfate solid adding port are connected to the hydroxylamine sulfate configuration tank, and the hydroxylamine sulfate configuration tank is connected with the secondary oximation reactor through the hydroxylamine sulfate pipeline.

Preferably, the equipment system further comprises an oxime hydrolysis reactor, an oxime hydrolysis catalyst separator and a hydroxylamine sulfate separator, wherein the oxime hydrolysis reactor is connected with a sulfuric acid pipeline, the tower top pipeline and an oxime hydrolysis catalyst pipeline, an oxime hydrolysis reaction liquid pipeline is connected out, and is connected with the organic solvent extraction tower through the tower top pipeline and is connected with the oxime hydrolysis catalyst separator through the oxime hydrolysis reaction liquid pipeline; the oxime hydrolysis catalyst separator is connected with an oxime hydrolysis catalyst circulating pipeline and an oxime hydrolysis reaction clear liquid pipeline, is connected with the oxime hydrolysis reactor through the oxime hydrolysis catalyst circulating pipeline, and is connected with the hydroxylamine sulfate separator through the oxime hydrolysis reaction clear liquid pipeline; the hydroxylamine sulfate separator is connected with the hydroxylamine sulfate pipeline and the cyclohexanone recovery pipeline and is connected with the secondary oximation reactor through the hydroxylamine sulfate pipeline.

Preferably, the equipment system further comprises an oxime hydrolysis reactor, an oxime hydrolysis catalyst separator and a hydroxylamine sulfate separator, wherein the oxime hydrolysis reactor is connected with a sulfuric acid pipeline, the cyclohexanone oxime pipeline and an oxime hydrolysis catalyst pipeline, an oxime hydrolysis reaction liquid pipeline is connected out, and the oxime hydrolysis reaction liquid pipeline is connected with the oxime hydrolysis catalyst separator; the oxime hydrolysis catalyst separator is connected with an oxime hydrolysis catalyst circulating pipeline and an oxime hydrolysis reaction clear liquid pipeline, is connected with the oxime hydrolysis reactor through the oxime hydrolysis catalyst circulating pipeline, and is connected with the hydroxylamine sulfate separator through the oxime hydrolysis reaction clear liquid pipeline; and the hydroxylamine sulfate separator is connected with a cyclohexanone recovery pipeline and a hydroxylamine sulfate pipeline, and is connected with the secondary oximation reactor through the hydroxylamine sulfate pipeline.

Preferably, the secondary oximation reactor is a packed tower type reverse-flow reactor or a tank type reactor.

Preferably, the secondary oximation reactor is a kettle-type reactor, and a sedimentation separator is connected behind the kettle-type reactor, the secondary oximation reactor is only connected with a secondary oximation reaction liquid pipeline, the secondary oximation reaction liquid pipeline is connected with the sedimentation separator, the sedimentation separator is connected with a cyclohexanone oxime solution pipeline and a hydroxylamine sulfate circulation pipeline, the hydroxylamine sulfate circulation pipeline is connected with the secondary oximation reactor, and a water phase discharge pipeline is connected to the hydroxylamine sulfate circulation pipeline. The hydroxylamine sulfate circulating pipeline is connected to a secondary oximation reaction, the hydroxylamine sulfate solution in the hydroxylamine sulfate circulating pipeline is recycled, and the reaction ratio is adjusted; the aqueous phase discharge line is used for discharging an aqueous phase solution containing low-concentration hydroxylamine sulfate and ammonium sulfate.

Preferably, the direct ammoximation reactor is provided with a tail gas discharge pipeline.

Preferably, the catalyst recycling line is connected with a catalyst recycling line.

When catalyst deactivation is detected or after a period of recycle, the catalyst is withdrawn through a catalyst recovery line and then regenerated.

Preferably, the oxime hydrolysis catalyst circulating line is connected with an oxime hydrolysis catalyst line.

Preferably, the oxime hydrolysis catalyst recycling line is connected with an oxime hydrolysis catalyst recycling line.

Preferably, the tower kettle is also connected with a waste water discharge pipeline.

The invention has the beneficial effects that:

(1) the production process is obtained by the inventor through field data acquisition and experimental analysis for many years, the inventor firstly discovers that the effective conversion rate of cyclohexanone in the direct ammoximation process does not reach the expected 99.5-99.95 percent, the actual conversion rate is only 98-99 percent, and the main impurities in the cyclohexanone oxime are cyclohexylimine, polymers of cyclohexylimine, octahydrophenazine and the like, and a new reaction mechanism is proposed based on the above, on the basis of a new reaction mechanism, the effective conversion rate of the cyclohexanone is improved to 99.98 percent by adjusting the proportion of the cyclohexanone, ammonia and hydrogen peroxide and combining the secondary oximation reaction and the condition control of the secondary oximation reaction, so that the purity of the cyclohexanone oxime product reaches 99.98 percent, namely the impurity content of cyclohexanone, cyclohexylimine polymer, octahydrophenazine and the like is less than 200ppm (wt), so as to obtain a high-quality cyclohexanone oxime product;

(2) the production process improves the effective conversion rate of the cyclohexanone, namely reduces the unit consumption of the cyclohexanone, taking a 12 ten thousand tons/year caprolactam device as an example, the unit consumption of the cyclohexanone of the caprolactam can be reduced by 2 percent, namely 2400 tons/year caprolactam can be produced when the same amount of cyclohexanone raw materials are put into; the quality of caprolactam is improved, a large amount of caprolactam can be exported, and the selling unit price of each ton of caprolactam can be improved by 1000-2000 yuan; the production cost of removing hydroxylamine sulfate by a 12-kiloton/year device can increase the economic benefit of 1-2 million yuan per year; if 300 million tons/year of cyclohexanone in China are directly produced by the ammoximation process, the economic benefit per year can reach 30-60 million yuan;

(3) the production process reduces the consumption of hydrogen peroxide, avoids the discharge of nitrogen-containing oxides caused by excessive hydrogen peroxide to oxidize ammonia water, and can reduce more than 50 percent of pollutant N compared with the prior art of direct ammoximation of cyclohexanone₂Discharging O; meanwhile, the concentration of hydrogen peroxide in the reaction liquid is lower, and the safety coefficient is higher.

(4) The production process adopts the cyclohexanone oxime produced by the primary oximation and the hydroxylamine sulfate aqueous solution produced by sulfuric acid to carry out the secondary oximation on the cyclohexanone or the cyclohexylimine which is not completely reacted, thereby basically realizing closed cycle, not needing to newly add raw material types and saving the cost for purchasing new raw materials;

(5) the equipment system has simple and reasonable structure, and a small amount of equipment and line reconstruction are added on the basis of the original equipment system for producing caprolactam, so that the equipment can be combined to form a whole set of equipment for continuously producing high-quality and high-yield cyclohexanone oxime, and the production of high-quality caprolactam is facilitated; in the preferred scheme of the equipment system of the invention, the secondary oximation of cyclohexanone is realized in the equipment system on the premise of not purchasing hydroxylamine sulfate, so that the purchase of new raw materials is avoided.

Drawings

FIG. 1 is a schematic structural diagram of an equipment system according to embodiment 1 of the present invention;

FIG. 2 is a schematic structural diagram of an equipment system according to embodiment 2 of the present invention;

fig. 3 is a schematic structural diagram of an apparatus system of embodiment 3 of the present invention.

In the figure: 10-a direct ammoximation reactor, 11-a reaction liquid pipeline, 12-a reaction material pipeline and 13-a tail gas discharge pipeline; 20-a membrane separator, 21-a catalyst circulating pipeline, 22-a reaction clear liquid pipeline, and 23-a catalyst recovery pipeline; 30-an organic solvent extraction tower, 31-an organic solvent pipeline, 32-a tower top pipeline, 33-a tower kettle pipeline and 34-a wastewater discharge pipeline; 40-a secondary oximation reactor, 41-an ammonia pipeline, 42-a hydroxylamine sulfate pipeline, 43-a cyclohexanone oxime pipeline, 44-a cyclohexanone oxime solution pipeline, 45-a water phase discharge pipeline, 46-a sedimentation separator, 47-a secondary oximation reaction liquid pipeline, and 48-a hydroxylamine sulfate circulation pipeline; 50-oxime hydrolysis reactor, 51-sulfuric acid pipeline, 52-oxime hydrolysis reaction liquid pipeline, and 53-oxime hydrolysis catalyst pipeline; 60-hydroxylamine sulfate separator, 61-cyclohexanone recovery pipeline; 70-a rearrangement reactor; an 80-tert-butyl alcohol recovery tower, an 81-tert-butyl alcohol recovery pipeline and an 82-water phase reaction liquid pipeline; a 90-toluene recovery column; 100-hydroxylamine sulfate configuration tank, 101-process water pipeline, 102-hydroxylamine sulfate solid inlet; a 111-oxime hydrolysis catalyst separator, a 112-oxime hydrolysis reaction clear liquid pipeline and a 113-oxime hydrolysis catalyst circulating pipeline.

Detailed Description

The present invention will be further described with reference to the following examples.