CN112939808A - Preparation method of cyclohexanone oxime - Google Patents

Abstract

The present invention relates to a preparation method of cyclohexanone oxime. Partial oxidation reaction of cyclohexylamine and molecular oxygen occurs under the action of a catalyst to obtain an oxidation reaction product consisting of cyclohexanone oxime, by-products and possibly unconverted cyclohexylamine; then the oxidation reaction product is carried out in one of the following ways. Treatment: (i) without separation, or after first separating some or all of the water, under the action of a catalyst, simultaneously carry out hydroamination reaction with H ₂ and NH ₃ or hydrogenation and then amination reaction, and then obtain by separation Cyclohexanone oxime; (ii) without separation, or after first separating part or all of the water, hydrogenation reaction with H ₂ is carried out under the action of a catalyst, and then cyclohexanone oxime is obtained by separation. The method of the invention has the characteristics of short process flow, less land occupation and investment, low material consumption and energy consumption (low cost), simple operation and more environment-friendly.

Description

Preparation method of cyclohexanone oxime

Technical Field

The invention relates to a preparation method of cyclohexanone oxime.

Background

Cyclohexanone oxime is an intermediate of an important raw material epsilon-caprolactam (the main application is to further prepare nylon fibers, engineering plastics, plastic films and the like by generating polyamide slices through polymerization).

There are two main processes for producing cyclohexanone oxime known at present: the cyclohexanone-hydroxylamine process and the cyclohexanone ammoximation process. The two methods are most commonly applied, and both of the two methods take benzene as a starting material to synthesize cyclohexanone oxime through an intermediate cyclohexanone.

There are currently three methods in industry for the synthesis of cyclohexanone starting from benzene: phenol, cyclohexane oxidation and cyclohexene hydration processes.

The phenol method has been well known, and the earliest cyclohexanone oxime production device in the world adopts the phenol method to produce cyclohexanone: firstly, benzene is used as a raw material to produce phenol, then the phenol is hydrogenated to generate cyclohexanol, and then the cyclohexanol is dehydrogenated to prepare cyclohexanone. It can be seen that the key to the phenol process is how phenol is obtained. At present, the cumene method is mainly adopted for producing phenol in industry (the chlorobenzene hydrolysis method and the benzene sulfonation method are almost completely eliminated due to the problems of environment and cost): benzene and propylene are alkylated to generate cumene, the cumene reacts with oxygen to generate cumene hydroperoxide, and finally the cumene hydroperoxide is decomposed into phenol and acetone under the action of sulfuric acid or sulfonic acid resin. This method mainly has the following disadvantages: firstly, the yield of phenol is low (72-75%) and the number of byproducts is large; secondly, the separation and purification device of phenol and acetone is complex and has high energy consumption; thirdly, the market demand and price of a large amount of acetone by-product can affect the production cost of phenol. Thus, the process for preparing cyclohexanone from phenol was, at an early start, gradually replaced by the cyclohexane oxidation process.

The technology for preparing cyclohexanone by oxidizing cyclohexane is mature, and currently, a two-step synthesis method is widely adopted in industry: (i) cyclohexane is subjected to non-catalytic oxidation reaction in molecular oxygen to mainly generate cyclohexyl hydroperoxide, and simultaneously generate a certain amount of cyclohexanone and cyclohexanol as well as a plurality of byproducts; (ii) the cyclohexyl hydrogen peroxide in the oxidation product obtained in the last step is decomposed into cyclohexanone and cyclohexanol (meanwhile, some byproducts are also generated) by a low-temperature alkaline decomposition method, then KA oil is obtained by separation, the KA oil is further separated into cyclohexanone and cyclohexanol, and finally the cyclohexanol is dehydrogenated into the cyclohexanone. The method has the main advantages that the technology for preparing cyclohexane by completely hydrogenating benzene is mature, the difficulty is small, the yield is high, but the oxidation process of cyclohexane has three major disadvantages: (i) in order to maintain high selectivity, the conversion rate of cyclohexane in one pass of cyclohexane air oxidation can only be controlled to 3-5%, and a large amount of unconverted cyclohexane needs to consume a large amount of energy to separate and circulate the unconverted cyclohexane, even if the total yield of KA oil (a mixture of cyclohexanone and cyclohexanol) finally calculated by cyclohexane can only reach about 83%, so that the consumption of cyclohexane is high, and the amount of byproducts is large. (ii) The main product of the non-catalytic oxidation reaction of cyclohexane is cyclohexyl hydrogen peroxide, NaOH is consumed in the decomposition process of the cyclohexyl hydrogen peroxide, and byproducts of the oxidation reaction of cyclohexane mainly comprise acid, ester, ether and the like, and also need to be saponified and removed by an alkaline aqueous solution, so that a large amount of NaOH needs to be consumed and a large amount of waste saponification alkali liquor needs to be generated, and not only is the production cost high, but also the environmental pressure is large. (iii) Because the target product is cyclohexanone, the KA oil needs to be further separated into cyclohexanone and cyclohexanol through rectification, and the cyclohexanol is dehydrogenated into cyclohexanone; however, due to the limitation of thermodynamic equilibrium, the single-pass conversion rate of cyclohexanol dehydrogenation is generally less than 80%, so that cyclohexanol and cyclohexanone are separated after dehydrogenation, the difference between the boiling points of cyclohexanone and cyclohexanol is only about 6 ℃, the separation difficulty can cause higher energy consumption, and the single-pass conversion rate of cyclohexane oxidation is only 3-5%, so that the energy consumption of the whole process is very high.

In summary, although the two-step method for preparing cyclohexanone by oxidizing cyclohexane, which is widely used in industry at present, has a technical threshold which is not high and is relatively mature, the two-step method has the problem of three-high one: namely high cyclohexane consumption, high energy consumption, high alkali consumption, large environmental pressure (waste alkali liquid treatment load) and the like.

Therefore, in recent years, new cyclohexanone oxime industrial devices generally adopt a cyclohexene hydration route proposed in the 2002 of asahi formation to prepare cyclohexanone (CN 02804368.5, CN 02814607.7), which is called cyclohexene water combination route or cyclohexene hydration method for short, and the preparation process schematic diagram is shown in fig. 1: partial hydrogenation of benzene is carried out to generate cyclohexene and cyclohexane, the cyclohexene is separated from the cyclohexane and unconverted benzene through extractive distillation, then the cyclohexene and water are subjected to hydration reaction to generate cyclohexanol, and finally the cyclohexanol is dehydrogenated to generate cyclohexanone. The method has the greatest advantages of low material consumption: firstly, the total selectivity of cyclohexene and cyclohexane generated by partial hydrogenation of benzene is very high (up to 99%), and cyclohexane is a product or an intermediate with certain economic value; secondly, the hydration of cyclohexene to cyclohexanol is also essentially a directional conversion reaction.

However, the cyclohexene hydration process also has three distinct disadvantages. Firstly, the energy consumption is very high: (i) in order to obtain the highest possible single pass yield of cyclohexene, the conversion rate of the benzene partial hydrogenation reaction is generally controlled to be 40-50% (corresponding cyclohexene selectivity is about 70-80%), so that the benzene partial hydrogenation product is actually a mixture consisting of benzene, cyclohexene and cyclohexane with very close boiling points, and can be separated only by a so-called four-tower process, namely two-stage extractive distillation and two-stage vacuum distillation: the first stage of extractive distillation is to separate benzene from cyclohexene and cyclohexane by using an extractant, and then separate the benzene from the extractant by vacuum rectification for respective recycling; the second stage of extractive distillation is to separate cyclohexene from cyclohexane by using an extracting agent, then separate the cyclohexene from the extracting agent by vacuum distillation, and the separated cyclohexane can be refined and sold as a product. Therefore, the separation difficulty and the energy consumption of the benzene-cyclohexene-cyclohexane system are high; (ii) the conversion rate of cyclohexene hydration to cyclohexanol is generally only 10-12%, so that higher energy is consumed for separation of a cyclohexene-cyclohexanol-water system and recycling of a large amount of cyclohexene; (iii) because the target product is cyclohexanone, cyclohexanol obtained by hydration needs to be dehydrogenated into cyclohexanone, energy needs to be provided in the dehydrogenation process for preparing the cyclohexanone by dehydrogenation, the conversion rate of the cyclohexanol does not exceed 80% generally due to the limitation of reaction balance, the boiling point difference between the cyclohexanone and the cyclohexanol is only about 6 ℃, and therefore larger energy needs to be provided for separating cyclohexanone from the cyclohexanol (the cyclohexanol obtained by separation is also used for preparing the cyclohexanone by circulating dehydrogenation). Secondly, cyclohexane is taken as a main byproduct of the partial hydrogenation of benzene, and the problem of how to treat the benzene is also a problem due to the large yield and the small market demand; at present, the industrial method mainly adopts a cyclohexane oxidation method and a cyclohexene hydration method to be matched for construction so as to digest the cyclohexane which is a byproduct of the cyclohexene hydration method. Thirdly, the benzene partial hydrogenation adopts a noble metal catalyst, which is not only expensive, but also has higher requirement on the purity of the raw material benzene because the benzene is easy to be poisoned.

In addition to these problems in the production of cyclohexanone, which is an intermediate, there are problems in the process for producing cyclohexanone oxime by oximation of cyclohexanone itself. At present, two cyclohexanone hydroxylamine oximation methods and two cyclohexanone ammoximation methods are mainly used in industry, wherein the cyclohexanone hydroxylamine oximation method can be divided into a hydroxylamine sulfate oximation method (HSO method) and a hydroxylamine phosphate oximation method (HPO method). Both HSO and HPO require a complex hydroxylamine salt production line, and the produced hydroxylamine salt is used for carrying out hydroxylamine oximation on cyclohexanone to generate cyclohexanone oxime. In general, the cyclohexanone hydroxylamine oximation method not only has long production flow, large equipment investment and complex operation control, but also has high hydrogen consumption and material consumption (the yield of hydroxylamine salt based on ammonia is only about 60 percent), thereby having high production cost.

In order to reduce the oximation cost and improve the atom utilization rate of oximation reaction, the HAO method (U.S. Pat. No. 4745221) was developed by einy italy in the last 80 th century, and industrialization was realized: cyclohexanone reacts with hydrogen peroxide and ammonia in one step under the action of a titanium silicalite molecular sieve catalyst to generate cyclohexanone oxime. Compared with HSO and HPO, the HAO method has the advantages of low hydrogen consumption, short production flow, simple and convenient control, low requirements on equipment and pipeline materials, less investment and occupied area and the like. However, the HAO method also has some disadvantages, mainly in two aspects: firstly, hydrogen peroxide is consumed, so a matched hydrogen peroxide production line is needed, and the hydrogen peroxide concentration in the hydrogen peroxide is not too high, and water is generated in the ammoximation reaction process, so the method has large waste water generation amount and heavy treatment load. Secondly, tertiary butanol is required to be introduced into the catalytic reaction, and is evaporated after the reaction is finished, so that the energy consumption is additionally increased.

In addition to the above-mentioned process for producing cyclohexanone oxime by oximation of cyclohexanone, there is also a process which can be referred to as "cyclohexane photonitrosation process", which is a process for producing cyclohexanone oxime without using cyclohexanone as an intermediate: a process for the photochemical reaction of cyclohexane and nitrosyl chloride, obtainable by reacting nitrosylsulfuric acid (NOHSO4) with HCl, to give cyclohexanone oxime hydrochloride. The method has the advantages of few reaction steps and short flow, but has the disadvantages of very high power consumption (for generating light sources), high cost of light source equipment and troublesome maintenance, and is eliminated.

Furthermore, U.S. Pat. Nos. 2967200A (1959) and 3255261A (1964) propose a process for producing cyclohexanone oxime without using cyclohexanone as an intermediate: cyclohexane reacts with nitric acid to obtain nitrocyclohexane, and then partial hydrogenation is carried out to obtain cyclohexanone oxime. Although the method has simple steps, a plurality of problems still exist, such as: the nitration reaction condition of the cyclohexane and the nitric acid is harsh (the temperature is 150-; the selectivity of cyclohexanone oxime obtained by partially hydrogenating nitrocyclohexane is less than 60 percent. Because of these limitations, there has been no report of industrialization since the advent of this method for more than half a century.

In fact, there is also a process for the preparation of cyclohexanone oxime that has been attracting attention since the 50 s of the last century: the production of cyclohexanone oxime by partial oxidation of cyclohexylamine (Journal of Molecular Catalysis A: Chemical,2000,160: 393-402). Early studies focused on the use of hydrogen peroxide or alkyl hydroperoxides as oxidants, such as those proposed in U.S. Pat. No. 4,2718528 (1955) and U.S. Pat. No. 3,3960954 (1976). Later, in view of the cost problem of the oxidant, research was gradually focused on the aspect of using molecular oxygen as the oxidant, and for example, united states corporation proposed in 1982 that a silica gel was used as the catalyst and molecular oxygen was used as the oxidant, and gas-solid phase catalytic oxidation of cyclohexylamine was performed at 150 ℃ so that the selectivity of cyclohexanone oxime was 60% when the conversion of cyclohexylamine was 18% (US 4337358). In 1985, the company also proposes that the gas-solid phase catalytic oxidation is carried out at 159 ℃ by using gamma-alumina loaded tungsten oxide as a catalyst and molecular oxygen as an oxidant, the conversion rate of the cyclohexylamine can reach 28 percent, and the selectivity of the cyclohexanone oxime can reach 54 percent (US 4504681); if the gamma-alumina is adopted to load molybdenum oxide, the conversion rate of the cyclohexylamine can reach 33 percent, and the selectivity of the cyclohexanone oxime can reach 64 percent (J.of Catalysis,1983,83: 487-one 490). However, until the end of this century, there has been no major progress in the research on the partial oxidation of cyclohexylamine with molecular oxygen to cyclohexanone oxime. For example, CN 103641740a (2013) discloses a gas-phase catalytic oxidation method using supported mesoporous silicon as a catalyst, wherein when the conversion rate of cyclohexylamine is 20-30%, the selectivity of cyclohexanone oxime can reach more than 85%; CN 109206339A (2017) discloses a liquid-phase catalytic oxidation method using supported titanium dioxide as a catalyst, wherein when the conversion rate of cyclohexylamine reaches more than 50%, the selectivity of cyclohexanone oxime can reach more than 90%.

In combination with the preparation of cyclohexylamine and the process for preparing cyclohexanone oxime by partial oxidation thereof, japan limited, has also proposed a process for producing cyclohexanone oxime by partial oxidation of cyclohexylamine with molecular oxygen in 2002 (CN 02804368.5, CN 02814607.7): cyclohexanol obtained by a cyclohexene hydration method is used as a raw material, firstly, the cyclohexanol is subjected to amination reaction with ammonia to generate cyclohexylamine, and then, the cyclohexylamine is subjected to partial oxidation reaction with molecular oxygen under the action of a catalyst to generate cyclohexanone oxime. In order to obtain higher cyclohexanone oxime yield, the byproducts (called byproduct-alpha and byproduct-beta, respectively) generated in the two reactions need to be separated and recycled to the amination system for amination to generate cyclohexylamine. The advantages of the method are very obvious: firstly, cyclohexanol does not need to be dehydrogenated into cyclohexanone, so that energy consumption is reduced; secondly, because the oximation of the cyclohexanone is not needed, the hydroxylamine salt or hydrogen peroxide is not needed to be consumed, and a matched hydroxylamine salt or hydrogen peroxide production line is not needed, so the production cost can be obviously reduced compared with the cyclohexanone-hydroxylamine method and the cyclohexanone-ammoximation method, and the method has the advantages of short flow, less investment and simple and convenient operation and control. However, this method still has the following disadvantages: firstly, because the cyclohexene hydration route is still adopted to prepare cyclohexanol, the problem of high energy consumption cannot be avoided; the other is that the involved cyclohexanol amination and cyclohexane oxidation reactions produce some byproducts with boiling points close to or higher than that of cyclohexanone oxime, for example, nitrocyclohexane has a boiling point of 205-206 ℃ and is very close to that of cyclohexanone oxime of 206-210 ℃, and dicyclohexylamine and N-cyclohexylcyclohexylimine have boiling points higher than that of cyclohexanone oxime. Thus, the separation of cyclohexanone oxime from these near boiling or higher boiling by-products is not only very difficult, but the energy requirements can also be very high.

In view of the above, with the continuous development and progress of society, it is required to develop a simpler, more efficient and more environmentally friendly method for producing cyclohexanone oxime.

Disclosure of Invention

According to the deep understanding and analysis of the prior art, in order to realize the simpler, more efficient and more environmentally friendly production of cyclohexanone oxime, the invention provides a preparation method of cyclohexanone oxime, as shown in fig. 1 and fig. 2.

According to the preparation method of the cyclohexanone oxime, the cyclohexylamine and molecular oxygen are subjected to partial oxidation reaction under the action of a solid catalyst to obtain an oxidation reaction product consisting of the cyclohexanone oxime, byproducts and the cyclohexanone amine which may not be converted; then the oxidation reaction product is processed in one of the following modes to obtain the cyclohexanone oxime:

(i) without separation, or after partial or all water is separated out by rectification, the product is reacted with H under the action of catalyst₂And NH₃Simultaneously carrying out hydrogenation amination reaction or hydrogenation-followed amination reaction, and then carrying out rectification separation to obtain cyclohexanone oxime;

(ii) without separation, or after partial or all water is separated out by rectification, the product is reacted with H under the action of catalyst₂Hydrogenation reaction is carried out, and then cyclohexanone oxime is obtained through separation.

Further, the molecular oxygen is oxygen, air or other inert gas containing oxygen; the by-product is one or more than two of water, cycloheximide, cyclohexanone, nitrocyclohexane, N-cyclohexylcycloheximide, dicyclohexylamine and the like.

Further, the hydrogenation amination or hydrogenation-first amination or hydrogenation-second amination is a reaction process with or without water diversion.

Further, the hydrogenation amination is to oxidize the by-product and H in the reaction product under the action of a catalyst₂And NH₃Simultaneously, hydrogenation amination reaction is carried out to convert the mixture into the cyclohexylamine and the cyclohexanone oxime; the hydrogenation and amination are carried out by oxidizing the by-product and H in the reaction product under the action of a catalyst₂And NH₃Hydrogenation and amination are carried out successively to convert the mixture into the cyclohexylamine and the cyclohexanone oxime; after they are separated, the cyclohexylamine is circulated to carry out partial oxidation reaction.

Further, the hydrogenation is to oxidize the by-product and H in the reaction product under the action of the catalyst₂Hydrogenation reaction is carried out to convert the cyclohexane into cyclohexylamine and cyclohexanone oxime and a small amount of dicyclohexylamine and cyclohexanol, and the cyclohexylamine and the cyclohexanol are separated, wherein the cyclohexylamine is circularly subjected to partial oxidation reaction.

Further, the catalyst used for the partial oxidation of the cyclohexylamine is a surface hydroxyl-rich catalyst or a supported catalyst thereof.

Further, the catalyst used for the partial oxidation of cyclohexylamine is an oxide catalyst such as silica gel, metasilicic acid, anatase type titanium dioxide, titanium phosphorus oxide, aluminum oxide or tungsten trioxide, etc., the surface of which is rich in hydroxyl groups, or TiO₂/MCM-41,WO₃/Al₂O₃Or a supported catalyst such as TiPO/silica gel. For example, WO with rich hydroxyl groups on the surface at a reaction temperature of 100 ℃ under an oxygen pressure of 1.2MPa₃Or supported WO₃The catalyst/MCM-41 has cyclohexylamine converting rate up to 40%, cyclohexanone oxime selectivity up to 90%, and the rest being cyclohexanone, nitrocyclohexane, cycloheximide and N-cyclohexyl cycloheximide.

Further, a catalyst used for hydrogenation amination is formed by hydrotalcite or hydrotalcite-like compound transition metal simple substance active components, wherein the transition metal simple substance active components comprise main active components and auxiliary active components, the main active components are selected from one or more than two of transition metals in the VIII group of the periodic table of elements, and the auxiliary active components are selected from one or more than two of transition metals in the IB-VIIB group of the periodic table of elements; the active component of the catalyst used for hydrogenation is selected from one or more than two of VIII group transition metals in the periodic table of elements, and the auxiliary active component is selected from one or more than two of IB-VIIB group transition metals in the periodic table of elements.

Furthermore, the main active component of the catalyst used for hydrogenation amination is one or more than two of Ni, Co, Ru, Rh, Pt or Pd, and the auxiliary active component is one or more than two of Cu, Zn, Zr or Mn; the catalyst for hydrogenation has one or more of Ni, Co, Ru, Rh, Pt and Pd as active component and one or more of Cu, Zn, Zr and Mn as auxiliary active component.

Further, the solid catalyst for hydrogenation amination or hydrogenation first and then amination or hydrogenation is a catalyst formed by hydrotalcite or hydrotalcite-like compound transition metal elementary substance active components, wherein the transition metal elementary substance active components comprise a main active component and an auxiliary active component, the main active component is one or more than two of transition metals selected from VIII group in the periodic table of elements, preferably nickel, platinum and the like; the auxiliary active component is one or more than two of transition metals selected from IB-VIIB groups in the periodic table of elements, preferably copper, iron and the like. For example, cyclohexanone, nitrocyclohexane, cyclohexylimine, N-cyclohexylcyclohexylcyclohexylimine, etc. are almost completely converted into cyclohexylamine or cyclohexanone oxime by using hydrotalcite-based NiCu/MgAlO as a catalyst under the conditions of a reaction temperature of 100 ℃ and a pressure of hydrogen and ammonia of 1.0 MPa.

Further, the cyclohexylamine can be synthesized by one of the following methods: (a) from nitrobenzene or aniline with H₂Carrying out catalytic hydrogenation reaction; (b) from nitrocyclohexane and H₂Carrying out catalytic hydrogenation reaction; (c) from KA oil, i.e. a mixture of cyclohexanone and cyclohexanol, with H₂And NH₃Simultaneously carrying out catalytic hydrogenation amination reaction; (d) from cyclohexanol and NH₃Carrying out catalytic amination reaction; (e) from cyclohexene and NH₃Carrying out catalytic addition reaction.

In order to more clearly understand the present invention, the following description is made with reference to fig. 1 and 2 and the detailed technical solutions.

As shown in fig. 1 and 2, cyclohexanone oxime is prepared from cyclohexylamine as a raw material through two-step reaction:

(1) partial oxidation of cyclohexylamine with molecular oxygen: the cyclohexylamine and molecular oxygen are partially oxidized under the action of a solid catalyst to generate cyclohexanone oxime. Compared with the prior industrial technology for preparing cyclohexanone oxime by oximation of cyclohexanone, the partial oxidation of the cyclohexylamine and molecular oxygen does not need to consume hydroxylamine salt or hydrogen peroxide, and the production cost can be greatly reduced. However, while cyclohexanone oxime is produced by the partial oxidation reaction of cyclohexylamine with molecular oxygen, a certain amount of by-products are also produced: besides water, the other component is one or more than two of cyclohexanone, nitrocyclohexane, dicyclohexylamine, cycloheximide (CAS: 22554-30-9), N-cyclohexylcycloheximide (CAS: 10468-40-3) and the like.

Generally, the selectivity of the by-products of the partial oxidation reaction may reach about 6% to 12%, or even higher, and if not converted for recycling, it is a big problem from the economic point of view and from the environmental point of view. Thus, Japanese Asahi chemical synthesis (CN 02814607.7) proposed to separate them from cyclohexanone oxime and then return them to amination with ammonia and hydrogen to regenerate cyclohexylamine. However, the by-products are substantially the same as the cyclohexanone oxime as the main product except for moisture, and especially, most of the by-product components have boiling points close to or higher than that of cyclohexanone oxime, such as the boiling point of nitrocyclohexane is 205-206 ℃ and close to that of cyclohexanone oxime at 206-210 ℃, and the boiling points of dicyclohexylamine and N-cyclohexylcyclohexylimine are above 255 ℃, which shows that they are practically difficult to separate from cyclohexanone oxime by the conventional method, and the energy consumption for separation may be very high, which is very limited in practical industrial application.

Under the action of the catalyst, the reaction of cyclohexylamine with molecular oxygen may occur mainly as follows:

(1a)C₆H₁₁NH₂+O₂→C₆H₁₀NOH+H₂O

(1b)C₆H₁₁NH₂+1.5O₂→C₆H₁₁NO₂+H₂O

(1c)C₆H₁₁NH₂+0.5O₂→C₆H₁₀NH+H₂O

(1d)2C₆H₁₁NH₂+3.5O₂→2C₆H₁₀O+3H₂O+2NO

(1e)C₆H₁₀O+C₆H₁₁NH₂→C₆H₁₀＝N-C₆H₁₁+H₂O

(1f)2C₆H₁₁NH₂+2.5O₂→2C₆H₁₁OH+H₂O+2NO

(1g)C₆H₁₁OH+C₆H₁₁NH₂→(C₆H₁₁)₂NH+H₂O

as can be seen from the above reaction schemes, the side reactions (1d) and (1f) to cyclohexanone and cyclohexanol, which not only bring N or NH themselves, should be strictly controlled₃And further consumption of cyclohexylamine by the cyclohexanone and cyclohexanol formed, to form N-cyclohexylcyclohexylcyclohexylimine and dicyclohexylamine. It is possible that cyclohexanol is rarely found in the oxidation by-product, because the rate of cyclohexanol formation reaction (1f) is slower than that of its consumption reaction (1 g).

(2) Hydrogenated amination or hydrogenation followed by amination or hydrogenation of the oxidation product: in order to solve the problem of separating cyclohexanone oxime from byproducts in the oxidation reaction product, the invention provides a new method which comprises the following steps: (i) separating the oxidation reaction product of cyclohexylamine without separation, or rectifying to separate partial or all water, and mixing with H₂And NH₃Carrying out hydrogenation amination reaction or hydrogenation-followed amination reaction under the action of a catalyst, further converting an oxidation by-product into cyclohexanone oxime or cyclohexylamine, and then carrying out rectification separation to obtain the cyclohexanone oxime and the cyclohexylamine; or (ii) separating the oxidation reaction product of the cyclohexylamine without separation or after separating part or all of the water by rectification,then reacts with H under the action of catalyst₂The hydrogenation reaction is carried out, the byproducts are further converted into cyclohexanone oxime, cyclohexylamine, dicyclohexylamine and the like, and the cyclohexanone oxime can be separated by rectification due to the large difference between the boiling points of the cyclohexanone oxime and the dicyclohexylamine, the cyclohexanol and the cyclohexylamine, particularly the difference between the boiling point of the cyclohexanone oxime and the boiling point of the cyclohexylamine is more than 70 ℃, so that the problem that the oxidized byproducts are difficult to separate can be solved.

Oxidizing the byproduct component and H under the action of catalyst₂And/or NH₃The main reactions that may occur are as follows (equation):

(2a)C₆H₁₀O+H₂→C₆H₁₁OH

(2b)C₆H₁₀＝N-C₆H₁₁+H₂→(C₆H₁₁)₂NH

(2d)C₆H₁₁NO₂+H₂→C₆H₁₀NOH+H₂O

(2e)C₆H₁₁NO₂+3H₂→C₆H₁₁NH₂+2H₂O

(2f)C₆H₁₀O+NH₃+H₂→C₆H₁₁NH₂+H₂O

(2g)C₆H₁₀＝N-C₆H₁₁+NH₃+H₂→2C₆H₁₁NH₂

(2h)(C₆H₁₁)₂NH+NH₃→2C₆H₁₁NH₂

(2i)C₆H₁₁OH+NH₃→C₆H₁₁NH₂+H₂O

in fact, due to the high cyclohexylamine content in the reaction system, the following reactions also exist:

(2j)C₆H₁₀O+C₆H₁₁NH₂→C₆H₁₀＝N-C₆H₁₁+H₂O

(2k)C₆H₁₁OH+C₆H₁₁NH₂→(C₆H₁₁)₂NH+H₂O

obviously, if H is used₂And NH₃The oxidation product of the cyclohexylamine is subjected to hydrogenation amination reaction or hydrogenation and amination reaction, the byproduct is converted into cyclohexanone oxime and the cyclohexylamine, and then the rectification separation is simpler. If it is subjected to only hydrogenation and then separated, dicyclohexylamine can be obtained as another by-product.

In addition, cyclohexanone oxime may also undergo hydrolysis reaction under the action of a catalyst to form cyclohexanone and hydroxylamine, which may further decompose under reaction conditions:

(2l)C₆H₁₀NOH+H₂O→C₆H₁₀O+NH₂OH

(2m)4NH₂OH→2NH₃+N₂O+3H₂O

(2n)3NH₂OH→NH₃+N₂+3H₂O

therefore, the water should be removed as timely as possible before or during the hydroamination or hydrogenation followed by amination or hydrogenation to minimize hydrolysis of the cyclohexanone oxime.

The method of the invention mainly has the following two characteristics: (i) compared with the oximation route of cyclohexanone, the method avoids the consumption of hydroxylamine salt or hydrogen peroxide, does not need a production line matched with the hydroxylamine salt or the hydrogen peroxide, greatly reduces the material consumption and the energy consumption, and greatly reduces the occupied area and the investment. (ii) Because the oxidation reaction of the cyclohexylamine and the molecular oxygen can not avoid generating a certain amount of by-products with physical properties similar to those of the cyclohexanone-oxime, the problems of high separation difficulty and high energy consumption are caused, the invention proposes that the ring is not separated firstlyThe oxidation reaction product of the hexylamine or only part or all of the water in the reaction product is separated and directly mixed with H₂And NH₃Hydrogenating amination or hydrogenation and amination or hydrogenation under the action of a catalyst to convert other byproducts into the cyclohexanone or the cyclohexanone oxime, and then separating the cyclohexanone and the cyclohexanone oxime, thereby solving the problems of difficult separation and high energy consumption of the cyclohexanone oxime and the oxidation byproducts.

In conclusion, the method has the characteristics of short process flow, small occupied area and investment, low material consumption and energy consumption (low cost), simple and convenient operation, more environment-friendly property and the like.

Drawings

FIGS. 1 and 2 are schematic diagrams of a process for preparing cyclohexanone oxime from cyclohexylamine according to the present invention, which are provided for convenience of illustration and the present invention, and are not intended to limit the present invention.

Detailed Description

The following examples are intended to illustrate the invention, but not to limit it.

(1) Partial oxidation of cyclohexylamine

Example 1: weighing 15 g (purity 99.9%) of cyclohexylamine and WO₃/Al₂O₃Adding 0.5 g of catalyst into a 100 ml reaction kettle, introducing oxygen, maintaining the pressure of the reaction kettle at 1.0MPa, reacting at 100 ℃ for 4 hours, cooling to room temperature, filtering and separating out the solid catalyst to obtain 16.25 g of liquid oxidation reaction product. The solution was subjected to qualitative analysis by gas chromatograph-mass spectrometer and quantitative analysis by gas chromatography internal standard method (chlorobenzene as internal standard), and measured to be 8.78 g of cyclohexylamine, 6.42 g of cyclohexanone oxime, 0.45 g of byproduct nitrocyclohexane, 0.15 g of cyclohexanone, 0.07 g of cycloheximide, and 0.03 g of N-cyclohexylcycloheximide, and the conversion of cyclohexylamine, the selectivity of cyclohexanone oxime, nitrocyclohexane, cyclohexanone and N-cyclohexylcycloheximide in the process were calculated to be 41.6%, 90.2%, 5.5%, 2.5%, 1.2%, and 0.6%, respectively.

This example was repeated several times and all of the liquid oxidation reaction products were collected for use in the following examples. The mass percentages of the components in the collected liquid oxidation reaction product are as follows: 53.9 percent of cyclohexylamine, 39.6 percent of cyclohexanone oxime, 2.7 percent of nitrocyclohexane, 0.9 percent of cyclohexanone, 0.5 percent of cyclohexylimine and 0.2 percent of N-cyclohexylcyclohexylcyclohexylimine.

Example 2: the procedure is as in example 1, except that anatase TiO is used₂As catalyst, the following were obtained: the conversion rate of the cyclohexylamine was 42.5%, the selectivity for cyclohexanone oxime was 92.8%, the selectivity for nitrocyclohexane was 4.6%, the selectivity for cyclohexanone was 1.5%, the selectivity for cycloheximide was 0.5%, and the selectivity for N-cyclohexylcycloheximide was 0.6%.

(2) Hydrogenated amination or hydrogenation of the oxidation reaction product:

example 3: weighing 0.1 g of hydrotalcite-based Pd-Cu/MgAlO catalyst and 12.98 g of liquid oxidation reaction product prepared by the method in example 1, putting the weighed materials into a 50 ml high-pressure kettle, slowly replacing the materials with hydrogen for 4-5 times, closing an inlet valve and an outlet valve, introducing 0.1 MPa ammonia gas, introducing hydrogen gas, maintaining the pressure of the reaction kettle at 1.0MPa, reacting at 120 ℃ for 3 hours, and cooling to room temperature; the solid catalyst was separated by filtration to obtain 13.05 g of a mixed solution. The solution was subjected to qualitative analysis by gas chromatograph-mass spectrometer and quantitative analysis by gas chromatography internal standard method (chlorobenzene was used as internal standard), and measured to be 7.40 g of cyclohexylamine, 5.22 g of cyclohexanone oxime, and 0.001 g of N-cyclohexylcyclohexylcyclohexylimine. Finally, 7.1 g of cyclohexylamine with the purity of 99.9 percent and 5.1 g of cyclohexanone oxime with the purity of 99.8 percent are obtained by rectification separation.

Example 4: the procedure and the procedure were as in example 3 except that 13.58 g of the liquid oxidation reaction product was used and that 0.89 g of water and 0.13 g of cyclohexylamine were separated by distillation under reduced pressure, followed by hydroamination reaction to give 12.62 g of a mixed solution, and that 7.11 g of cyclohexylamine, 5.46 g of cyclohexanone oxime, and 0.001 g of dicyclohexylamine were measured. Finally, 7.0 g of cyclohexylamine with the purity of 99.9 percent and 5.2 g of cyclohexanone oxime with the purity of 99.8 percent are obtained by rectification separation.

Example 5: the procedure and procedure were the same as in example 3 except that 12.85 g of the liquid oxidation reaction product was used and that only hydrogen gas (no ammonia gas) was fed and hydrotalcite-based Pt-Zn/MgAlO was used as the catalyst to give 12.91 g of a mixed solution, and that 6.93 g of cyclohexylamine, 5.15 g of cyclohexanone oxime, 0.07 g of cyclohexanol and 0.30 g of dicyclohexylamine were measured. Finally, 6.8 g of the cyclohexylamine with the purity of 99.8 percent and 5.0 g of the cyclohexanone oxime with the purity of 99.8 percent are obtained by rectification and separation.

Example 6: the operation method and the procedure were the same as in example 5 except that 12.84 g of a liquid oxidation reaction product was used, and 0.78 g of water and 0.11 g of cyclohexylamine were separated by distillation under reduced pressure and reacted to obtain 12.05 g of a mixed solution, and it was found that 6.24 g of cyclohexylamine, 5.38 g of cyclohexanone oxime, 0.08 g of cyclohexanol and 0.15 g of dicyclohexylamine were used. Finally, 6.1 g of the cyclohexylamine with the purity of 99.9 percent and 5.2 g of the cyclohexanone oxime with the purity of 99.8 percent are obtained by rectification and separation.

Claims (9)

1. a preparation method of cyclohexanone oxime, is characterized in that, cyclohexylamine takes place partial oxidation reaction with molecular oxygen under the effect of catalyzer, obtains to be made up of cyclohexanone oxime, by product and possibly unconverted cyclohexylamine The oxidation reaction product, then the oxidation reaction product is processed in one of the following ways to obtain cyclohexanone oxime: (i) without separation, or after first separating some or all of the water, then simultaneously carry out hydroamination reaction with H ₂ and NH ₃ under the action of a catalyst or hydrogenation and then amination reaction, and then obtain by separation Cyclohexanone oxime and cyclohexylamine, wherein the cyclohexylamine cycle is partially oxidized; (ii) without separation, or after first separating part or all of the water, _{hydrogenation} is carried out with H under the action of a catalyst, and then cyclohexanone oxime, cyclohexylamine and a small amount of bicyclic are obtained by separation Hexylamine, in which cyclohexylamine recycles for partial oxidation. 2. method as claimed in claim 1, described molecular oxygen is oxygen, air or other oxygen-containing inert gas; Described oxidation reaction by-product is water, cyclohexylimine, cyclohexanone, nitro ring One or two or more of hexane, N-cyclohexylcyclohexylimine and dicyclohexylamine. 3. The method according to claim 1, wherein the hydroamination or first hydrogenation followed by amination or hydrogenation is a reaction process of coupled water separation or uncoupled water separation. 4. The method according to any one of claims 1 to 3, wherein the hydroamination is that under the action of a catalyst, the by-product in the oxidation reaction product and H ₂ and NH ₃ simultaneously undergo a hydroamination reaction and convert into Cyclohexylamine and cyclohexanone oxime; the first hydrogenation and then amination is that under the action of a catalyst, the by-products in the oxidation reaction product and H ₂ and NH ₃ undergo hydrogenation and amination reactions successively and are converted into cyclohexylamine and Cyclohexanone oxime; separate cyclohexylamine for partial oxidation. 5. The method according to any one of claims 1 to 3, wherein the hydrogenation is that under the action of a catalyst, by-products other than water and H ₂ undergo a hydrogenation reaction, and are converted into cyclohexylamine and cyclohexanone Oxime and a small amount of dicyclohexylamine and cyclohexanol; separate cyclohexylamine and recycle for partial oxidation. 6. method as claimed in claim 1, the catalyzer that cyclohexylamine oxidation adopts is surface hydroxyl-rich catalyst or its supported catalyst, such as silica gel, metasilicic acid, anatase titanium dioxide, titanium phosphorus oxide, aluminum oxide or three. Oxides such as tungsten oxide, or supported catalysts such as TiO ₂ /MCM-41, WO ₃ /Al ₂ O ₃ or TiPO/silica gel. 7. method as claimed in claim 1, the catalyst that hydroamination or amination adopts is formed by hydrotalcite or hydrotalcite-like composite transition metal simple substance active component, wherein transition metal simple substance active component comprises main active group and auxiliary active components, the main active components are selected from one or more of transition metals in Group VIII in the periodic table, and the auxiliary active components are selected from IB to VIIB in the periodic table of elements One or more of the transition metals of the Group; the active components of the catalyst used in the hydrogenation are selected from one or more of the transition metals of Group VIII in the periodic table, and the auxiliary active components are selected from the periodic table of the elements One or more of transition metals from Groups IB to VIIB in the table. 8. method as claimed in claim 7, the main active component of the catalyst that hydroamination or amination adopts is one or more in Ni, Co, Ru, Rh, Pt or Pd, auxiliary active component It is one or more of Cu, Zn, Zr or Mn; the active component of the catalyst used in hydrogenation is one or more of Ni, Co, Ru, Rh, Pt or Pd, and the auxiliary active component It is one or more of Cu, Zn, Zr or Mn. 9. method as claimed in claim 1, described cyclohexylamine can come from the synthetic method of one of following: (a) by nitrobenzene or aniline and H Carry out catalytic _{hydrogenation} reaction; (b) by nitro Catalytic _{hydrogenation of cyclohexane} and H ₃ carries out catalytic amination reaction; (e) carries out catalytic addition reaction from cyclohexene with NH ₃ .

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