CN111253281A

CN111253281A - Preparation method of cyclohexanone oxime

Info

Publication number: CN111253281A
Application number: CN202010103344.0A
Authority: CN
Inventors: 罗和安; 游奎一; 倪文金; 刘平乐; 艾秋红
Original assignee: Xiangtan University
Current assignee: Xiangtan University
Priority date: 2020-02-19
Filing date: 2020-02-19
Publication date: 2020-06-09
Anticipated expiration: 2040-02-19
Also published as: CN111253281B

Abstract

The invention relates to a preparation method of cyclohexanone oxime, which mainly comprises three synthesis steps of aniline or nitrobenzene hydrogenation catalysis, cyclohexylamine oxidation, byproduct amination and the like: (1) aniline or nitrobenzene and hydrogen are subjected to hydrogenation reaction under the action of a catalyst to generate cyclohexylamine and a small amount of byproduct-A, and the byproduct-A and the aniline which is possibly not completely converted are separated to obtain cyclohexylamine; (2) performing oxidation reaction on the cyclohexylamine obtained in the step (1) and molecular oxygen under the action of a catalyst to obtain an oxidation reaction product mainly comprising cyclohexanone oxime, a small amount of byproduct-B and possibly unconverted cyclohexylamine; (3) directly carrying out amination reaction on the oxidation reaction product obtained in the step (2) with ammonia and hydrogen under the action of a catalyst without separation, completely converting a byproduct-B in the oxidation reaction product into cyclohexylamine, and separating the cyclohexylamine to obtain the cyclohexanone oxime. The invention can obviously improve the yield of the cyclohexanone-oxime and obviously reduce the energy consumption and the cost of the production of the cyclohexanone-oxime.

Description

Preparation method of cyclohexanone oxime

Technical Field

The invention relates to preparation of cyclohexanone oxime, and in particular 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 oxidized with molecular oxygen under the condition of no catalysis to generate cyclohexyl hydroperoxide (simultaneously generating 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 large energy to separate and circulate the unconverted cyclohexane, even if the total yield of KA oil (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 cyclohexane non-catalytic oxidation reaction is cyclohexyl hydrogen peroxide, NaOH is consumed in the decomposition process of the cyclohexyl hydrogen peroxide, and byproducts of the cyclohexane oxidation reaction mainly comprise acid, ester, ether and the like, and also need to be saponified and removed through 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 alkali consumption, high energy consumption, large treatment load of waste alkali liquor and the like.

Therefore, in recent years, new cyclohexanone oxime industrial equipment generally adopts a cyclohexene hydration route (CN 02804368.5, CN 02814607.7) proposed in japan asahi 2002, 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, it also has the obvious disadvantage of being very energy intensive, as represented by: (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% (at the time, the selectivity of cyclohexene is about 70-80%), so that the reaction product of benzene partial hydrogenation is actually a mixture consisting of benzene, cyclohexene and cyclohexane with very close boiling points, and currently, the separation can be carried out only by two-stage extractive distillation and reduced-pressure 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). In addition, although cyclohexane, a by-product of the partial hydrogenation of benzene, has a certain economic value, it is also necessary to consider its sale and utilization problems due to its large production volume and limited market demand.

In addition to the problems with cyclohexanone production described above, oximation of cyclohexanone itself presents several problems. 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. Therefore, the cyclohexanone-hydroxylamine oximation method has the advantages of long production flow, large equipment investment, complex operation control, high hydrogen consumption and material consumption (the yield of the hydroxylamine salt based on ammonia is only about 60 percent), and high production cost.

In order to reduce the oximation cost and improve the atom utilization rate of oximation reaction, the Italy Eyni company develops a cyclohexanone ammoximation method, namely an HAO method (U.S. Pat. No. 4,4745221 (1988)), and realizes industrialization: namely, 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 requires a hydrogen peroxide production line, which requires consumption of hydrogen peroxide, and the production of water in the ammoximation reaction is not so high, which results in a large amount of wastewater and a heavy treatment load.

In addition to the above-mentioned process for producing cyclohexanone oxime by oximation of cyclohexanone, there is also a process for producing cyclohexanone oxime which does not use cyclohexanone as an intermediate, which may be referred to as "cyclohexane photonitrosation process": process for the photochemical reaction of cyclohexane and nitrosyl chloride, from which nitrosylsulfuric acid (NOHSO) is obtained, to form cyclohexanone oxime hydrochloride₄) Reacting with HCl. The method has the advantages of less reaction steps and short flow, but the method has the advantages of less reaction steps and short flowThe power consumption is very high (for generating light sources), and the cost of light source equipment is high, the maintenance is troublesome, and the production is stopped for a long time.

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 a process for the preparation of cyclohexanone oxime that has been attracting attention since the 50 s of the last century: the cyclohexylamine is partially oxidized to form cyclohexanone oxime (J. 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, 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%; CN109206339A (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%.

The synthesis of cyclohexanone and its partial oxidation to cyclohexanone oxime, the Japan Asahi formation proposed in 2002 a new process for producing cyclohexanone oxime based on the partial oxidation of cyclohexanone and molecular oxygen (CN 02804368.5, CN 02814607.7). The cyclohexanol obtained by the cyclohexene hydration process, starting from ammonia, is subjected to an amination reaction to form cyclohexanone oxime, and is subjected to a partial oxidation reaction with molecular oxygen under the action of a catalyst.The by-products (named by-products- α and by-product- β, respectively) formed in the two steps need to be separated and recycled to the amination system for the amination to form cyclohexanone oxime in order to obtain a higher cyclohexanone oxime yield.A significant advantage is obtained in that firstly, dehydrogenation of cyclohexanone to cyclohexanone is not required, energy consumption is reduced, secondly, no hydroxylamine salt or hydrogen peroxide is required, and certainly no hydroxylamine salt or hydrogen peroxide production line is required, and therefore the production costs can be significantly reduced compared to the cyclohexanone oxime production processes, and the investment is short, the operational control is simple and easy, and the process still has the disadvantages of the similar boiling point of cyclohexanone oxime production, such as the cyclohexanone oxime production process is not only a high boiling point, but also a high boiling point of cyclohexanone oxime production process, and a high boiling point of cyclohexanone oxime production process is possible, and a high boiling point of cyclohexanone oxime production, and a high boiling point of cyclohexanone oxime production process is avoided, and a high boiling point is still required for the cyclohexanone production process is also because the cyclohexanone oxime production process is very similar to the cyclohexanone production process is still required by-206.

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 environmentally friendly production of cyclohexanone oxime, the invention provides a novel method for preparing cyclohexanone oxime, which mainly comprises three synthesis steps of catalyzing aniline or nitrobenzene hydrogenation, oxidizing cyclohexane and aminating an oxidation product, and the like: (1) aniline or nitrobenzene and hydrogen are subjected to hydrogenation reaction under the action of a solid catalyst to generate cyclohexylamine and a small amount of byproduct-A (marked as byproduct-A), and the byproduct-A and aniline which may not be completely converted are separated to obtain cyclohexylamine. (2) Performing oxidation reaction on the cyclohexylamine obtained in the step (1) and molecular oxygen under the action of a solid catalyst to obtain an oxidation reaction product mainly comprising cyclohexanone oxime, a small amount of by-products (marked as by-products-B) and possibly unconverted cyclohexylamine; (3) directly carrying out amination reaction on the oxidation reaction product obtained in the step (2) with ammonia and hydrogen under the action of a solid catalyst without separation, completely converting a byproduct-B in the oxidation reaction product into cyclohexylamine, and separating the cyclohexylamine to obtain the cyclohexanone oxime.

The method of the invention mainly has the following three characteristics: (i) the cyclohexanone is not used as an intermediate to prepare the cyclohexanone oxime, so that the cyclohexanone is not required to be produced, and all the defects of the existing cyclohexanone production technology, such as high material consumption of a cyclohexane oxidation method or high energy consumption of a cyclohexene hydration method, and the like, are avoided, so that the energy is greatly saved and the consumption is reduced. (ii) The preparation of cyclohexanone oxime adopts the oxidation of cyclohexylamine and molecular oxygen instead of the oximation of cyclohexanone, so that the consumption of hydroxylamine salt or hydrogen peroxide is avoided, a matched production line of hydroxylamine salt or hydrogen peroxide is not needed, the material consumption and the energy consumption can be greatly reduced, and the occupied area and the investment can be greatly reduced. (iii) The oxidation reaction of cyclohexylamine with molecular oxygen also produces some by-products whose amount is not negligible, namely the above-mentioned by-product-B, which, if not used, will have a large influence on the yield of cyclohexanone oxime. However, some of these by-products have boiling points very close to or higher than that of cyclohexanone oxime, such as nitrocyclohexane, dicyclohexylamine, N-cyclohexylcyclohexylcyclohexane, etc., and thus, the separation of these by-products from cyclohexanone oxime is very difficult in practice and the energy consumption may be very high. The invention provides an oxidation reaction product of cyclohexylamine and molecular oxygen without separation, which is directly subjected to amination reaction with ammonia and hydrogen under the action of a solid catalyst, and after the oxidation byproducts are all converted into the cyclohexylamine, the cyclohexylamine and cyclohexanone oxime are separated, so that the problems of difficult separation and high energy consumption of the cyclohexanone oxime and the oxidation byproducts are solved.

Therefore, compared with the prior production technology, the novel method for preparing the cyclohexanone oxime by using the benzene as the starting material and through the hydrogenation of aniline or nitrobenzene, the molecular oxygen oxidation of the cyclohexylamine and the amination of the oxidation product, ammonia and hydrogen has the remarkable advantages of short process flow, low construction investment, low material consumption and energy consumption, simple and convenient operation, safety, environmental friendliness and the like.

For a clearer understanding of the present invention, the above steps of the present invention are described in detail below with reference to fig. 2:

(1) amination of aniline or nitrobenzene: aniline or nitrobenzene and hydrogen are subjected to hydrogenation reaction under the action of a solid catalyst to generate cyclohexylamine, and a small amount of a byproduct-A is generated; because nitrobenzene is easily converted into aniline, when nitrobenzene is used as a raw material, the nitrobenzene can be completely converted, but the conversion rate of aniline into cyclohexylamine is not necessarily complete or is not necessarily required to be complete, and can be adjusted according to needs; the boiling points of the cyclohexylamine, the aniline and the byproduct-A are different greatly, the cyclohexylamine, the aniline and the byproduct-A can be separated by vacuum rectification, and the separated aniline is circularly hydrogenated;

the hydrogenation of aniline or nitrobenzene mainly comprises the following reactions:

(a)C₆H₅NO₂+3H₂→C₆H₅NH₂+2H₂O

(b)C₆H₅NH₂+3H₂→C₆H₁₁NH₂+2H₂O

(d)

(e)

(f)

(g)

the reaction (a) is the hydrogenation of nitrobenzene to generate cyclohexylamine, the reaction (b) is the hydrogenation of aniline to generate cyclohexylamine, and the other four reactions are main side reactions: (d) (f) and (g) reactions of further hydrogenation of diphenylamine and N-cyclohexylaniline to dicyclohexylamine, respectively. However, the rate of nitrobenzene hydrogenation (a) is much faster than the other six reactions. Therefore, when nitrobenzene is used as a raw material for hydrogenation, it can be actually considered as a hydrogenation reaction using aniline as a raw material.

Under the catalytic reaction condition of the invention, the total amount of the generated by-product-A (the main component is one or more than two of dicyclohexylamine, N-cyclohexylaniline, diphenylamine and the like) is very small, and dicyclohexylamine in the byproduct-A is a product with better economic value and can be used for preparing intermediates for dyes, rubber accelerators, nitrocellulose lacquers, pesticides, catalysts, preservatives, gas phase corrosion inhibitors, fuel antioxidant additives and the like. Therefore, the byproduct-A can be collected, and then the hydrogenation reaction such as (f) and (g) can be further carried out under the action of the catalyst, so that the N-cyclohexylaniline and the diphenylamine in the product can be converted into the dicyclohexylamine, and the dicyclohexylamine can be obtained by separation and purification.

(2) Oxidation of cyclohexylamine with molecular oxygen: oxidation of cyclohexylamine with molecular oxygen: performing partial oxidation on the cyclohexylamine obtained in the step (1) and molecular oxygen 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, when cyclohexane is partially oxidized with molecular oxygen to form cyclohexanone oxime, a certain amount of by-product-B, i.e., one or more of cyclohexanone, nitrocyclohexane, dicyclohexylamine, cyclohexylimine (CAS: 22554-30-9), N-cyclohexylcyclohexylcyclohexylimine (CAS: 10468-40-3), and the like, is also formed.

In general, the selectivity of the by-product-B may reach about 6% to 12%, and if not recycled, it is a big problem from the economical and environmental aspects. Thus, Japanese Asahi chemosynthesis (CN 02814607.7) proposed to separate them from cyclohexanone oxime and return them to amination with ammonia and hydrogen to regenerate cyclohexylamine (see FIG. 1). However, in the by-product-B, the boiling points of other substances besides cyclohexanone and cycloheximide are very close to or higher than that of cyclohexanone oxime, for example, the boiling point of nitrocyclohexane is 205 ℃ to 206 ℃ and is very close to that of cyclohexanone oxime 206 ℃ to 210 ℃, and the boiling points of dicyclohexylamine and N-cyclohexylcyclohexylcyclohexylimine are above 255 ℃, which shows that the conventional method is difficult to separate from cyclohexanone oxime in practice and the energy consumption for separation can be very high.

The reaction of cyclohexylamine with molecular oxygen is mainly:

（a）

（b）

（c）

（d）

（e）

（f）

（g）

as can be seen from the above reaction schemes, the side reactions (d) and (f) to form cyclohexanone, 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. Since the rate of reaction (f) is relatively slow and the rate of reaction (g) is fast, cyclohexanol is rarely found in by-product-B.

(3) Amination of the oxidation product: in order to solve the problem of separating cyclohexanone oxime from a byproduct-B in the oxidation reaction product, the invention provides: the oxidation reaction product is first not subjected to any separation, but directly subjected to amination reaction with ammonia and hydrogen over a solid catalyst. Under the catalytic reaction conditions of the present invention, the by-product-B in the oxidation reaction product can be completely converted into cyclohexylamine, while cyclohexanone oxime does not undergo any reaction with ammonia and hydrogen. Since the boiling points of the cyclohexanone and the cyclohexanone oxime are greatly different, the cyclohexanone oxime and the cyclohexanone are easily separated by rectification.

The reaction scheme associated with the amination of by-product-B with ammonia and hydrogen is as follows:

（a）

（b）

（c）

（d）

（e）

further, in the step (1), the active component of the solid catalyst is selected from one or more of transition metals of group VIII in the periodic table of elements, preferably nickel, cobalt, copper, ruthenium, rhodium, palladium, etc. For example, when the conversion rate is close to 100 percent by adopting a catalyst loaded with cobalt, the selectivity of the cyclohexylamine can reach more than 90 percent; when the conversion rate is controlled to be about 90 percent, the selectivity of the cyclohexylamine can reach more than 97 percent.

Further, in the step (2), the solid catalyst is a surface hydroxyl-rich catalyst containing an active component, preferably titanium dioxide, silica gel, alumina, titanium phosphorus oxygen composite oxide, metatitanic acid, metasilicic acid, tungsten trioxide, or the like. For example, at the reaction temperature of 100 ℃ and under the oxygen pressure condition of 1.2MPa, the surface of the TiO rich in hydroxyl₂Or supported TiO₂The 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, in the step (3), the solid catalyst is a catalyst formed by hydrotalcite or hydrotalcite-like compound transition metal elementary substance active component, wherein the transition metal elementary substance active component comprises a main active component and an auxiliary active component, the main active component is one or more than two selected from transition metals in group VIII of 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 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, in the step (1), the aniline is obtained by catalytic hydrogenation of nitrobenzene or direct catalytic amination of benzene; the nitrobenzene is obtained by catalytic nitration of benzene.

Compared with the prior art such as the current method for industrially producing cyclohexanone oxime and the method proposed by Japanese Asahi chemical synthesis (shown in figure 1), the invention (shown in figure 2) has the advantages that:

(i) the new route for preparing cyclohexanone oxime by oxidizing cyclohexane from aniline or nitrobenzene not only avoids the problems of high cost and the like of hydrogen peroxide or hydroxylamine salt required in the process of oximation of cyclohexanone, but also avoids the problems of high material consumption and energy consumption and the like of preparing cyclohexanone by a cyclohexane oxidation route and a cyclohexene hydration route, can obviously improve the yield of cyclohexanone oxime, and simultaneously obviously reduces the energy consumption and the cost of producing cyclohexanone oxime.

(ii) The oxidation reaction product of the cyclohexylamine and the molecular oxygen is directly subjected to amination reaction with ammonia and hydrogen under the action of a solid catalyst without separation, and after all byproducts in the oxidation reaction product are converted into the cyclohexylamine, the cyclohexanone oxime and the cyclohexylamine are separated, so that the separation difficulty and the separation energy consumption can be obviously reduced.

(iii) The production flow of the new route is shortened, and the equipment investment, the production land and the like are obviously reduced.

Drawings

FIG. 1 is a schematic diagram of a process for preparing cyclohexanone oxime by the reaction of Asahi.

FIG. 2 is a schematic diagram of a cyclohexanone oxime preparation process according to the present invention.

Detailed Description

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

Example 1

Preparing nitrobenzene by benzene nitration: 23.4 g of benzene (analytically pure, purity > 99.8%) and 27.6 g of NO are weighed out₂(purity > 99.8%) and 0.5 g AlCl₃-SiO₂The acid catalyst is added into a 100 ml reaction kettle together, then 0.6Ma hydrogen is introduced to react for 2 hours at 25 ℃, and after the reaction is finished, the solid catalyst is separated by filtration to obtain 39.7 g of mixed solution. The solution is characterized by adopting a gas chromatograph-mass spectrometer, and is accurately quantified by adopting a gas chromatography internal standard method (chlorobenzene is used as an internal standard substance), and 0.11 g of benzene, 36.6 g of nitrobenzene and 0.012 g of by-product dinitrobenzene are measured, the conversion rate of the benzene in the process is 99.5 percent, and the selectivity of the nitrobenzene is 99.76 percent. And (3) rectifying and separating the filtrate obtained after the reaction to obtain the nitrobenzene with high purity.

Example 2

Hydrogenation of nitrobenzene to aniline: 30 g (purity of 99.8%) of nitrobenzene prepared by the method of example 1 and 0.5 g of Pd/C catalyst are weighed and added into a 100 ml reaction kettle, 30 g of ethylenediamine is added as a solvent, hydrogen is introduced (pressure is maintained at 1.0 MPa), reaction is carried out for 4 hours at 120 ℃, and after the reaction is finished, solid catalyst is separated by filtration to obtain 61.38 g of mixed solution. The solution is accurately quantified by a gas chromatography internal standard method (chlorobenzene is used as an internal standard substance), the content of nitrobenzene and reaction products in the solution is analyzed, the solution is qualitatively determined by a gas chromatograph-mass spectrometer, 0.36 g of the residual nitrobenzene is measured, 22.25 g of aniline is obtained, 0.179 g of diphenylamine serving as a byproduct is obtained, the conversion rate of the nitrobenzene in the process is 98.8%, and the selectivity of the aniline is 99.12%. The solution obtained after the reaction was subjected to rectification separation to obtain 21.5 g of aniline, the purity of which was measured to be 99.5%.

Example 3

Hydrogenation of nitrobenzene to cyclohexylamine: 30 g (purity of 99.8%) of nitrobenzene prepared by the method of example 1 and 0.5 g of Pt/C catalyst are weighed and added into a 100 ml reaction kettle, 30 g of ethylenediamine is added as a solvent, hydrogen is introduced (pressure is maintained at 1.2 MPa), reaction is carried out for 5 hours at 140 ℃, and after the reaction is finished, solid catalyst is separated by filtration to obtain 62.91 g of mixed solution. The solution was characterized by gas chromatograph-mass spectrometer and accurately quantified by gas chromatography internal standard method (chlorobenzene as internal standard), and the remaining nitrobenzene was 0.06 g, cyclohexylamine was 23.95 g, aniline as byproduct was 0.05 g, diphenylamine was 0.04 g, and cyclohexylaniline was 0.02 g. The conversion of nitrobenzene in this process was 99.8% and the selectivity of cyclohexylamine was 99.5%. And rectifying and separating the solution obtained after the reaction to obtain the high-purity cyclohexylamine.

Example 4

Hydrogenation of aniline to cyclohexylamine: 20 g of aniline (purity 99.5%) prepared according to the method of example 2 and 0.5 g of Ni/C catalyst were weighed and added into a 100 ml reaction kettle, 20 g of ethylenediamine was added as a solvent, hydrogen was introduced (pressure was maintained at 1.2 MPa), reaction was carried out at 140 ℃ for 4 hours, and after the reaction was completed, solid catalyst was separated by filtration to obtain 42.48 g of a mixed solution. The solution was characterized by GC-MS and quantified accurately by GC-MS (chlorobenzene as an internal standard) to obtain 0.46 g of aniline, 20.5 g of cyclohexylamine, 0.28 g of dicyclohexylamine as a by-product and 0.15 g of N-cyclohexylaniline. The aniline conversion in this process was 97.7% and the cyclohexylamine selectivity was 98.2%. And rectifying and separating the solution obtained after the reaction to obtain the high-purity cyclohexylamine.

Example 5

Partial oxidation of cyclohexylamine: 15 g (purity 99.9%) of cyclohexylamine prepared according to the process described in example 3 or example 4 and TiO were weighed out₂Adding 0.5 g/MCM-41 catalyst into a 100 ml reaction kettle, introducing oxygen (the pressure is maintained at 1.0 MPa), reacting for 4 hours at 100 ℃, and filtering and separating out the solid catalyst after the reaction is finished to obtain 16.25 g oxidation reaction liquid. The solution was characterized by a gas chromatograph-mass spectrometer and accurately quantified by a gas chromatography internal standard method (chlorobenzene as an 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 cyclohexylimine, and 0.03 g of N-cyclohexylcyclohexylcyclohexylimine, the conversion rate of cyclohexylamine in the process was 41.6%, the selectivity of cyclohexanone oxime was 90.2%, the selectivity of nitrocyclohexane was 5.5%, the selectivity of cyclohexanone was 2.5%, the selectivity of cyclohexylimine was 1.2%, and the selectivity of N-cyclohexylcyclohexylcyclohexylimine was 0.6%.

Example 6

Amination of byproducts: weighing 12.98 g of the oxidation reaction solution prepared by the method described in example 5 (wherein 7 g of cyclohexylamine, 5.14 g of cyclohexanone oxime, 0.12 g of cyclohexanone, 0.36 g of nitrocyclohexane, 0.06 g of cyclohexylimine and 0.02 g of N-cyclohexylcyclohexylcyclohexylcyclohexylcyclohexylimine) and 0.1 g of hydrotalcite-based Ni-Cu/MgAlO catalyst, adding the mixture into a 50 ml reaction kettle, introducing 0.1 MPa ammonia gas (the reaction pressure is maintained at 1.0 MPa) in a hydrogen state, reacting at 120 ℃ for 3 hours, filtering and separating out the solid catalyst after the reaction is finished to obtain 13.05 g of a mixed solution, qualitatively analyzing the mixed solution by using a gas chromatograph-mass spectrometer, and accurately quantifying by using a gas chromatography internal standard method (chlorobenzene is used as an internal standard substance), wherein the measured amount of cyclohexylamine is 7.40 g, the amount of cyclohexanone oxime is 5.22 g, and the amount of N-cyclohexylimine is 0.001 g. Finally, 7.3 g of cyclohexylamine with the purity of 99.9 percent, 5.2 g of cyclohexanone oxime with the purity of 99.8 percent is obtained by rectification separation.

Example 7

Taking 2 g of diphenylamine as a by-product obtained after 15 times of repetition in example 2 and 2 g of N-cyclohexylaniline as a by-product obtained after 15 times of repetition in example 3 as reaction raw materials, and taking 0.1 g of Ni-Co/gamma-Al₂O₃Adding the catalyst into a 50 ml reaction kettle, adding 20 g of ethylenediamine as a solvent, introducing hydrogen (the pressure is maintained at 1.0 MPa), reacting for 3 hours at 160 ℃, and filtering and separating out the solid catalyst after the reaction is finished to obtain 24.21 g of a mixed solution. The solution is accurately quantified by a gas chromatography internal standard method (chlorobenzene is used as an internal standard substance), the contents of diphenylamine, N-cyclohexylaniline and reaction products in the solution are analyzed, the solution is qualitatively determined by a gas chromatograph-mass spectrometer, and the residual diphenylamine and N-cyclohexylaniline are respectively 0.01 g and 0.005 g, so that 4.18 g of dicyclohexylamine is obtained. The diphenylamine conversion in this process was 99.5%, the N-cyclohexylaniline conversion was 99.75%, and the dicyclohexylamine selectivity was 99.76%. The solution obtained after the reaction was subjected to rectification separation to obtain 3.98 g of dicyclohexylamine, whose purity was measured to be 99.9%.

Claims

1. A preparation method of cyclohexanone oxime comprises the following steps:

(1) hydrogenation of aniline or nitrobenzene: aniline or nitrobenzene and hydrogen are subjected to hydrogenation reaction under the action of a solid catalyst to generate cyclohexylamine and a small amount of by-products, which are marked as by-products-A, and the by-products-A and aniline which is possibly not completely converted are separated to obtain cyclohexylamine;

(2) oxidation of cyclohexylamine: performing oxidation reaction on the cyclohexylamine obtained in the step (1) and molecular oxygen under the action of a solid catalyst to obtain an oxidation reaction product which mainly contains cyclohexanone oxime and also contains a small amount of by-products, namely a by-product-B and possibly unconverted cyclohexylamine;

(3) amination of the oxidation product: directly carrying out amination reaction on the oxidation reaction product obtained in the step (2) with ammonia and hydrogen under the action of a solid catalyst without separation, completely converting a byproduct-B in the oxidation reaction product into cyclohexylamine, and separating the cyclohexylamine to obtain the cyclohexanone oxime.

2. The method according to claim 1, wherein the byproduct-A in step (1) is one or more of dicyclohexylamine, N-cyclohexylaniline, and diphenylamine.

3. The process according to claim 1, wherein in step (1) the separation is carried out by distillation, the aniline obtained by separation is recycled for hydrogenation, and the by-product-A obtained by separation can be used directly as a by-product.

4. The method according to claim 1, wherein the byproduct-B in step (2) is one or more of cyclohexanone, nitrocyclohexane, cyclohexylimine, dicyclohexylamine and N-cyclohexylcyclohexylimine.

5. The method according to claim 1, wherein in the step (3), rectification is adopted for separation, and the separated cyclohexylamine is recycled for the oxidation reaction in the step (2).

6. The process according to any one of claims 1 to 5, wherein the active component of the solid catalyst in step (1) is one or more selected from transition metals belonging to group VIII of the periodic Table.

7. The method of claim 6, wherein the solid catalyst in step (2) is a surface hydroxyl-rich catalyst containing an active component.

8. The method according to claim 7, wherein the solid catalyst in step (3) is a catalyst formed by hydrotalcite or hydrotalcite-like compound transition metal elementary substance active component, wherein the transition metal elementary substance active component comprises a main active component and a co-active component, and the main active component is one or more than two selected from transition metals in group VIII of the periodic table of elements; the auxiliary active component is one or more than two of transition metals selected from IB-VIIB groups in the periodic table of elements.

9. The method according to claim 8, wherein the active component of the solid catalyst in step (1) is one or more selected from nickel, cobalt, copper, ruthenium, rhodium and palladium; the solid catalyst in the step (2) is one or more than two of titanium dioxide, silica gel, alumina, titanium phosphorus oxygen composite oxide, metatitanic acid, metasilicic acid and tungsten trioxide; in the solid catalyst in the step (3), the main active component is platinum or/and nickel, and the auxiliary active component is copper or/and iron.

10. The process of claim 1, wherein the aniline of step (1) is obtained by catalytic hydrogenation of nitrobenzene or by direct catalytic amination of benzene; the nitrobenzene is obtained by catalytic nitration of benzene.