Preparation method of cyclohexylamine and dicyclohexylamine, and method for controlling yield of dicyclohexylamine in reaction of co-production of cyclohexylamine and dicyclohexylamine

Abstract

The invention provides a preparation method of cyclohexylamine and dicyclohexylamine and a control method of dicyclohexylamine yield in cyclohexylamine and dicyclohexylamine co-production reaction, the method comprises the following steps: aniline and hydrogen are subjected to hydrogenation reaction in the presence of a catalyst to prepare cyclohexylamine and dicyclohexylamine, the raw materials also contain water, the water content is 0.1 wt%-3.0 wt% of the mass of aniline, and the water content is 0.1 wt%-3.0 wt% of the mass of hydrogen. The yield of cyclohexylamine and dicyclohexylamine is adjusted by adjusting the water content, and the flexibility and market competitiveness of a production device are improved.

Description

Technical Field

[0001] The invention belongs to the technical field of catalytic hydrogenation, and in particular relates to a method for preparing cyclohexylamine and dicyclohexylamine, and a method for controlling the output of dicyclohexylamine in a reaction of co-producing dicyclohexylamine from cyclohexylamine. Background Art

[0002] Cyclohexylamine and dicyclohexylamine are important organic chemical and fine chemical intermediates, widely used in rubber additives, food additives, metal corrosion inhibitors, antiseptics, papermaking and other fields. At present, the global market demand for cyclohexylamine is about 110,000 tons, and the market demand for dicyclohexylamine is about 20,000-30,000 tons. Cyclohexylamine and dicyclohexylamine are mainly prepared by the process of aniline hydrogenation. In actual industrial production, the ability to flexibly adjust the relative content of cyclohexylamine and dicyclohexylamine in the product is of great significance for responding to market changes and improving competitiveness.

[0003] U.S. Patent No. 5,728,883A discloses a method for preparing cyclohexylamine and dicyclohexylamine using a non-supported metal oxide as a catalyst, wherein the metal includes Co, Mn, alkaline earth metals, and V and / or VI main group metal elements. By changing the reaction temperature, the yield of cyclohexylamine can be adjusted between 47% and 92%, and the yield of dicyclohexylamine can be adjusted between 4% and 44%. The disadvantage is that when the reaction temperature is high, the content of byproducts benzene and cyclohexane is too high, resulting in a significant decrease in the total yield of cyclohexylamine and dicyclohexylamine, and frequent changes in the reaction temperature will shorten the service life of the catalyst.

[0004] Patent CN113200864B discloses a method for continuous production of cyclohexylamine and dicyclohexylamine. By optimizing the catalyst loading and the by-product recycling method, the ratio of cyclohexylamine to dicyclohexylamine can be maintained at 2.5:1, and the by-products are reduced and the total yield is improved. The disadvantage is that the ratio of cyclohexylamine to dicyclohexylamine cannot be adjusted, and the hydrogenation of the by-products requires additional equipment, which complicates the process and increases the investment.

[0005] How to create a preparation method with simple operation, high yield and adjustable yield of cyclohexylamine and dicyclohexylamine is of great significance. Summary of the invention

[0006] In order to solve the above technical problems, the present invention provides a method for preparing cyclohexylamine and dicyclohexylamine, which can adjust the yield of cyclohexylamine and dicyclohexylamine, so that the production of enterprises can be more flexibly adjusted according to market changes, and the by-product content is low, and the total yield of cyclohexylamine and dicyclohexylamine is high.

[0007] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0008] A method for preparing cyclohexylamine and dicyclohexylamine comprises: subjecting aniline and hydrogen to a hydrogenation reaction in the presence of a catalyst to prepare cyclohexylamine and dicyclohexylamine, wherein the raw material also contains water, the content of the water is 0.1wt%-3.0wt% of the mass of the aniline, and the yield of the cyclohexylamine and dicyclohexylamine is adjusted by adjusting the water content.

[0009] Preferably, the water may be added in hydrogen or in aniline or added separately.

[0010] Preferably, the water and aniline are first mixed and then reacted, or a mixed solution of aniline and water meeting the above water content is obtained during the preparation process of aniline.

[0011] Preferably, the reaction is carried out using a fixed bed reactor.

[0012] In the present invention, the catalyst is a cobalt and nickel supported catalyst.

[0013] Preferably, the catalyst further comprises an auxiliary agent, and the auxiliary agent is an alkaline earth metal oxide and a transition metal oxide. Furthermore, the alkaline earth metal is selected from one or more of Mg, Sr, and Ba; the transition metal is selected from one or more of Fe, Cu, Zn, and Mn.

[0014] Preferably, the carrier in the catalyst is CaCO3 or Ca(OH)2,

[0015] Preferably, the catalyst comprises Co3O4 and NiO.

[0016] In the present invention, in the catalyst, the mass content of Co3O4 is 40-45wt%, the mass content of NiO is 0.5-2%, the mass content of the auxiliary agent is 0.5-7wt%, and the mass content of the carrier is 46-59wt%.

[0017] Preferably, the mass content of the alkaline earth metal oxide is 0.01-2wt%, preferably 0.5-2wt%, and the mass content of the transition metal oxide is 0.01-5wt%, preferably 0.5-5wt%.

[0018] In one embodiment, the catalyst is prepared by a co-current co-precipitation method.

[0019] In some preferred embodiments of the present invention, the preparation method of the catalyst is: salts containing calcium, Co, Ni and auxiliary metals are configured into a mixed solution, the mixed solution and the precipitant are added into a container containing water at a temperature of 60-80°C and continuously stirred, aged for 8-12 hours, and then the precipitate is filtered and washed with water, and dried and burned to obtain the catalyst.

[0020] Preferably, the precipitating agent is a hydroxide, carbonate or bicarbonate of sodium or potassium;

[0021] Preferably, the drying temperature is 100-120°C and the drying time is 12-24h;

[0022] Preferably, the calcination temperature is 400-650° C. and the calcination time is 4-6 hours.

[0023] Preferably, calcination is carried out in an air or oxygen atmosphere.

[0024] Preferably, the catalyst is activated under hydrogen conditions before use.

[0025] Preferably, the catalyst activation temperature is 200-500° C., the activation pressure is 50-400 kPaG, and the activation time is 24-72 h.

[0026] In the present invention, the feed molar ratio of hydrogen to aniline is 10-15:1; preheating is performed before the reaction, the preheating temperature is 150-180°C, the reaction temperature is 170-190°C; the reaction pressure is 100-200 kPaG; the feed mass space velocity of aniline is 0.4-1 g 苯胺 / (g cat h).

[0027] The present invention also provides a method for controlling the output of dicyclohexylamine in the reaction of co-producing cyclohexylamine with dicyclohexylamine. The preparation method of the present invention is used to co-produce cyclohexylamine and dicyclohexylamine, and the yields of cyclohexylamine and dicyclohexylamine in the product are regulated by adjusting the water content in the raw materials.

[0028] When it is necessary to increase the yield of dicyclohexylamine in the product, the content of water in the raw material is increased; when it is necessary to reduce the yield of dicyclohexylamine, the content of water in the raw material is reduced.

[0029] Preferably, when the yield of dicyclohexylamine in the product is 1.0%-28.0%, the water content in the raw material is 0.1wt%-3.0wt% of the mass of aniline, and the yield of dicyclohexylamine in the product increases with the increase of water content.

[0030] In some preferred embodiments of the present invention, when the water content in the raw material is 0.1wt%-1wt% of the mass of aniline, the yield of cyclohexylamine in the reaction product is about 89.0%-98.5%, and the yield of dicyclohexylamine is about 1.0%-9.0%; when the water content in the aniline is 1wt%-2wt% of the mass of aniline, the yield of cyclohexylamine in the reaction product is about 81.0%-94.0%, and the yield of dicyclohexylamine is about 5.0%-17.0%; when the water content in the aniline is 2wt%-3wt% of the mass of aniline, the yield of cyclohexylamine in the reaction product is about 70.0%-88.0%, and the yield of dicyclohexylamine is about 11.0%-28.0%.

[0031] The beneficial effects of the present invention are:

[0032] 1) By adopting the method of the present invention, the content of cyclohexylamine and dicyclohexylamine in the reaction product can be regulated within a certain range by adjusting the water content in the raw material aniline, thereby improving the flexibility and market competitiveness of the production device;

[0033] 2) The total yield of cyclohexylamine and dicyclohexylamine is high. On the one hand, it is because the catalyst hydrogenation activity adopted in the present invention is high, the byproduct cyclohexanol and N-cyclohexylidenecyclohexylamine contents are all low, and on the other hand, it is not necessary to regulate the content of cyclohexylamine and dicyclohexylamine by raising the temperature, the byproduct benzene and cyclohexane contents are low, and the total yield of cyclohexylamine and dicyclohexylamine reaches more than 98%. DETAILED DESCRIPTION

[0034] The present invention is further described below by means of specific examples. The examples described in the present invention are only used to illustrate the present invention and do not limit the scope of the present invention.

[0035] Unless otherwise specified, the raw materials and reagents in the following examples and comparative examples were purchased from commercial sources.

[0036] The gas chromatography analysis conditions in the following examples are: Agilent DB-5 chromatographic column, injection port temperature 280°C, FID detector temperature 300°C, column flow rate 1.5 ml / min, hydrogen flow rate 30 ml / min, air flow rate 400 ml / min, and the programmed temperature rise mode is 50°C for 2 min, then heated to 80°C at 5°C / min, then heated to 280°C at 15°C / min and held for 10 min.

[0037] [Example 1]

[0038] Catalyst preparation:

[0039] Weigh 71.3 g of Na2CO3 and dissolve it in 672.6 g of deionized water to prepare solution A; weigh 45.5 g of calcium nitrate monohydrate, 81.6 g of cobalt nitrate hexahydrate, 1.9 g of nickel nitrate hexahydrate, 1.0 g of strontium nitrate, 2.7 g of zinc nitrate hexahydrate, and 1.9 g of copper nitrate monohydrate respectively, and dissolve the above metal salts in 523.8 g of deionized water to prepare solution B; control the water bath temperature to 70°C, and simultaneously add A and B dropwise into a three-necked flask containing 100 g of deionized water while stirring continuously. After the dropwise addition is completed, age for 10 hours, and then filter and wash the precipitate with deionized water until the pH value reaches 7; dry at 110°C for 18 hours, and calcine at 400°C in an air atmosphere for 6 hours to obtain the catalyst Cat-1 of the present invention.

[0040] [Example 2]

[0041] Catalyst preparation:

[0042] Weigh 65.4g of NaOH and dissolve it in 1635.9g of deionized water to prepare solution A; weigh 67.0g of calcium nitrate monohydrate, 72.5g of cobalt nitrate hexahydrate, 3.9g of nickel nitrate hexahydrate, 9.5g of magnesium nitrate hexahydrate, and 3.5g of manganese nitrate tetrahydrate respectively, and dissolve the above metal salts in 641.6g of deionized water to prepare solution B; control the water bath temperature to 70°C, and simultaneously add A and B dropwise into a three-necked flask containing 100g of deionized water while stirring continuously. After the dropwise addition is completed, age for 10h, and then filter and wash the precipitate with deionized water until the pH value reaches 7; dry at 120°C for 24h, and calcine at 500°C in an air atmosphere for 5h to obtain the catalyst Cat-2 of the present invention.

[0043] [Example 3]

[0044] Take 50g of the catalyst Cat-1 prepared in Example 1, load it into a fixed bed reactor, and activate it at 350°C and 100kpaG for 24h. After activation, mix the water-containing aniline (the water content in the aniline is 0.1% of the mass of the aniline) with hydrogen, control the molar ratio of hydrogen to aniline to be 10, preheat to 160°C and then pass it into the fixed bed reactor, control the reaction temperature to be 170°C, the pressure to be 150kpaG, and the mass space velocity of aniline to be 0.4g 苯胺 / (g cat h), and a cyclohexylamine reaction liquid was obtained, and analyzed by gas chromatography. The analysis showed that the aniline conversion rate was 100%, the cyclohexylamine yield was 98.5%, and the dicyclohexylamine yield was 0.8%.

[0045] [Example 4]

[0046] The main difference between this embodiment and embodiment 2 is that the water content is 1% of the mass of aniline, and the other conditions are the same as those of embodiment 2. Analysis of the reaction solution shows that the aniline conversion rate is 100%, the cyclohexylamine yield is 94.1%, and the dicyclohexylamine yield is 5.4%.

[0047] [Example 5]

[0048] The main difference between this embodiment and embodiment 2 is that the water content is 2% of the mass of aniline, and the other conditions are the same as those of embodiment 2. Analysis of the reaction solution shows that the aniline conversion rate is 100%, the cyclohexylamine yield is 87.7%, and the dicyclohexylamine yield is 11.6%.

[0049] [Example 6]

[0050] The main difference between this embodiment and embodiment 2 is that the water content is 3% of the mass of aniline, and the other conditions are the same as those of embodiment 2. Analysis of the reaction solution shows that the aniline conversion rate is 100%, the cyclohexylamine yield is 78.8%, and the dicyclohexylamine yield is 20.2%.

[0051] [Example 7]

[0052] Take 50g of the catalyst Cat-2 prepared in Example 2, load it into a fixed bed reactor, and activate it at 400°C and 200kpaG for 48h. After activation, mix the water-containing aniline (the water content of aniline is 0.5% of the mass of aniline) with hydrogen, control the molar ratio of hydrogen to aniline to be 10, preheat to 160°C and then pass it into the fixed bed reactor, control the reaction temperature to be 170°C, the pressure to be 150kpaG, and the mass space velocity of aniline to be 0.4g 苯胺 / (g cat h), and a cyclohexylamine reaction liquid was obtained, and analyzed by gas chromatography. The analysis showed that the aniline conversion rate was 100%, the cyclohexylamine yield was 96.2%, and the dicyclohexylamine yield was 3.2%.

[0053] [Example 8]

[0054] The main difference between this embodiment and embodiment 7 is that the water content is 1.5% of the mass of aniline, and the other conditions are the same as those of embodiment 7. Analysis of the reaction solution shows that the aniline conversion rate is 100%, the cyclohexylamine yield is 90.3%, and the dicyclohexylamine yield is 8.9%.

[0055] [Example 9]

[0056] The main difference between this embodiment and embodiment 7 is that the water content is 2.5% of the mass of aniline, and the other conditions are the same as those of embodiment 7. Analysis of the reaction solution shows that the aniline conversion rate is 100%, the cyclohexylamine yield is 80.7%, and the dicyclohexylamine yield is 18.3%.

[0057] [Comparative Example 1]

[0058] The main difference between this embodiment and embodiment 2 is that the water content is 0.01% of the mass of aniline, and the other conditions are the same as those of embodiment 2. Analysis of the reaction solution shows that the aniline conversion rate is 91.2%, the cyclohexylamine yield is 89.1%, and the dicyclohexylamine yield is 0.05%.

[0059] [Comparative Example 2]

[0060] The main difference between this embodiment and embodiment 2 is that the water content is 5% of the mass of aniline, and the other conditions are the same as those of embodiment 2. Analysis of the reaction solution shows that the aniline conversion rate is 87.1%, the cyclohexylamine yield is 78.1%, and the dicyclohexylamine yield is 0.8%.

[0061] The above is only a preferred embodiment of the present invention. It should be pointed out that ordinary technicians in this field can make several improvements and supplements without departing from the method of the present invention. These improvements and supplements should also be regarded as the scope of protection of the present invention.

Claims

1. A method for preparing cyclohexylamine and dicyclohexylamine, characterized in that: include: Cyclohexylamine and dicyclohexylamine are prepared by hydrogenating aniline and hydrogen in the presence of a catalyst, wherein the raw materials also contain water, and the water content is 0.1wt%-3.0wt% of the mass of the aniline.

2. The preparation method according to claim 1, characterized in that: The water can be added in hydrogen or aniline or added alone; Preferably, the water and aniline are first mixed and then reacted, or a mixed solution of aniline and water meeting the above water content is obtained during the preparation process of aniline.

3. The preparation method according to claim 1 or 2, characterized in that: The reaction is carried out using a fixed bed reactor; Preferably, the catalyst is a cobalt and nickel supported catalyst; Preferably, the catalyst further comprises an additive, wherein the additive is an alkaline earth metal oxide and a transition metal oxide, and further, the alkaline earth metal is selected from one or more of Mg, Sr, and Ba; the transition metal is selected from one or more of Fe, Cu, Zn, and Mn; Preferably, the carrier in the catalyst is CaCO3 or Ca(OH)2; Preferably, the catalyst comprises Co3O4 and NiO; Preferably, in the catalyst, the mass content of Co3O4 is 40-45wt%, the mass content of NiO is 0.5-2%, the mass content of the auxiliary agent is 0.5-7wt%, and the mass content of the carrier is 46-59wt%; Preferably, the mass content of the alkaline earth metal oxide is 0.01-2wt%, preferably 0.5-2wt%, and the mass content of the transition metal oxide is 0.01-5wt%, preferably 0.5-5wt%.

4. The preparation method according to any one of claims 1 to 3, characterized in that The preparation method of the catalyst is as follows: salts containing calcium, Co, Ni and auxiliary metals are configured into a mixed solution, the mixed solution and a precipitant are added into a container containing water at a temperature of 60-80°C and stirred continuously, aged for 8-12 hours, and then the precipitate is filtered and washed with water, and dried and burned to obtain the catalyst.

5. The preparation method according to claim 4, characterized in that: The precipitant is a hydroxide, carbonate or bicarbonate of sodium or potassium; Preferably, the drying temperature is 100-120°C and the drying time is 12-24h; Preferably, the calcination temperature is 400-650°C and the calcination time is 4-6h; Preferably, calcination is carried out in an air or oxygen atmosphere.

6. The preparation method according to any one of claims 1 to 5, characterized in that: The catalyst is activated under hydrogen conditions before use; Preferably, the catalyst activation temperature is 200-500° C., the activation pressure is 50-400 kPaG, and the activation time is 24-72 h.

7. The preparation method according to any one of claims 1 to 6, characterized in that: The feed molar ratio of hydrogen to aniline is 10-15:1; preheating is performed before the reaction, the preheating temperature is 150-180°C, and the reaction temperature is 170-190°C; the reaction pressure is 100-200 kPaG; the feed mass space velocity of aniline is 0.4-1 g 苯胺 / (g cat h).

8. A method for controlling the yield of dicyclohexylamine in the reaction of cyclohexylamine and dicyclohexylamine, wherein the yield of cyclohexylamine and dicyclohexylamine in the product is regulated by adjusting the water content in the raw materials according to the preparation method of any one of claims 1 to 7; Preferably, when the yield of dicyclohexylamine in the product needs to be increased, the content of water in the raw material is increased; when the yield of dicyclohexylamine needs to be reduced, the content of water in the raw material is reduced.

9. The control method according to claim 8, characterized in that: When the yield of dicyclohexylamine in the product is 1.0%-28.0%, the water content in the raw material is 0.1wt%-3.0wt% of the mass of aniline, and the yield of dicyclohexylamine in the product increases with the increase of water content; Preferably, when the water content in the raw material is 0.1wt%-1wt% of the mass of aniline, the yield of cyclohexylamine in the reaction product is about 89.0%-98.5%, and the yield of dicyclohexylamine is about 1.0%-9.0%; when the water content in the aniline is 1wt%-2wt% of the mass of aniline, the yield of cyclohexylamine in the reaction product is about 81.0%-94.0%, and the yield of dicyclohexylamine is about 5.0%-17.0%; when the water content in the aniline is 2wt%-3wt% of the mass of aniline, the yield of cyclohexylamine in the reaction product is about 70.0%-88.0%, and the yield of dicyclohexylamine is about 11.0%-28.0%.