A method for preparing cyclohexylamine and dicyclohexylamine, and a method for controlling the yield of dicyclohexylamine in the reaction for co-producing cyclohexylamine and dicyclohexylamine

Abstract

The application provides a preparation method of cyclohexylamine and dicyclohexylamine, and a control method of dicyclohexylamine yield in cyclohexylamine and dicyclohexylamine reaction, which comprises: carrying out hydrogenation reaction of aniline and hydrogen in the presence of a catalyst to prepare cyclohexylamine and dicyclohexylamine, wherein the raw material also contains water, and the content of water is 0.1wt%-3.0wt% of the mass of aniline; the yield of cyclohexylamine and dicyclohexylamine is adjusted by adjusting the water content, and the flexibility and market competitiveness of the production device are improved.

Description

Technical Field

[0001] This invention belongs to the field of catalytic hydrogenation technology, specifically relating to a method for preparing cyclohexylamine and dicyclohexylamine, and a method for controlling the yield of dicyclohexylamine in the reaction of cyclohexylamine co-producing dicyclohexylamine. Background Technology

[0002] Cyclohexylamine and dicyclohexylamine are important intermediates in organic and fine chemicals, widely used in rubber additives, food additives, metal corrosion inhibitors, preservatives, and papermaking. Currently, the global market demand for cyclohexylamine is approximately 110,000 tons, and for dicyclohexylamine, it is approximately 20,000-30,000 tons. Cyclohexylamine and dicyclohexylamine are mainly produced using the hydrogenation process of aniline. In actual industrial production, the ability to flexibly adjust the relative content of cyclohexylamine and dicyclohexylamine in the products is crucial for responding to market changes and enhancing competitiveness.

[0003] US Patent 5728883A discloses a method for preparing cyclohexylamine and dicyclohexylamine using unsupported metal oxides as catalysts, wherein the metals include Co, Mn, alkaline earth metals, and Group V and / or VI metals. By changing the reaction temperature, the yield of cyclohexylamine can be adjusted between 47% and 92%, and the yield of dicyclohexylamine between 4% and 44%. However, a drawback is that at higher reaction temperatures, the content of byproducts benzene and cyclohexane is excessively high, leading to a significant decrease in the overall yield of cyclohexylamine and dicyclohexylamine. Furthermore, frequent changes in reaction temperature shorten the catalyst's lifespan.

[0004] Patent CN113200864B discloses a method for the continuous production of cyclohexylamine and dicyclohexylamine. By optimizing catalyst loading and byproduct reuse, the ratio of cyclohexylamine to dicyclohexylamine can be maintained at 2.5:1, while reducing byproducts and increasing the overall yield. However, the drawbacks are that the ratio of cyclohexylamine to dicyclohexylamine cannot be adjusted, and hydrogenation of the byproducts requires additional equipment, resulting in a complex process and increased investment.

[0005] It is of great significance to develop a simple, high-yield preparation method for cyclohexylamine and dicyclohexylamine with adjustable yields. Summary of the Invention

[0006] To address the above technical problems, this invention provides a method for preparing cyclohexylamine and dicyclohexylamine. This method allows for adjustment of the yields of cyclohexylamine and dicyclohexylamine, enabling enterprises to adjust their production more flexibly according to market changes. Furthermore, it results in low by-product content and high total yields of cyclohexylamine and dicyclohexylamine.

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

[0008] A method for preparing cyclohexylamine and dicyclohexylamine includes: reacting aniline and hydrogen in the presence of a catalyst to prepare cyclohexylamine and dicyclohexylamine, wherein the raw materials also contain water, the water content being 0.1wt%-3.0wt% of the mass of aniline, and the yield of cyclohexylamine and dicyclohexylamine is adjusted by adjusting the water content.

[0009] Preferably, the water can be added to hydrogen or aniline or added alone.

[0010] Preferably, the water and aniline are mixed before the reaction, or a mixture of aniline and water with the above-mentioned water content is obtained during the preparation of aniline.

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

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

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

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

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

[0016] In this invention, the catalyst contains 40-45 wt% Co3O4, 0.5-2% NiO, 0.5-7 wt% additives, and 46-59 wt% support.

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

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

[0019] In some preferred embodiments of the present invention, the catalyst is prepared by: preparing a mixed solution containing calcium, Co, Ni and an auxiliary metal; adding the mixed solution and a precipitant to a water-containing container at a temperature of 60-80°C and stirring continuously; aging for 8-12 hours; then filtering and washing the precipitate with water; and drying and calcining to obtain the catalyst.

[0020] Preferably, the precipitant is a sodium or potassium hydroxide, carbonate, or bicarbonate;

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

[0022] Preferably, the roasting temperature is 400-650℃ and the roasting time is 4-6 hours.

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

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

[0025] Preferably, the catalyst is activated at a temperature of 200-500℃, an activation pressure of 50-400 kPaG, and an activation time of 24-72 h.

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

[0027] This invention also provides a method for controlling the yield of dicyclohexylamine in the reaction of cyclohexylamine co-production of dicyclohexylamine. The method described in this invention is used to co-produce cyclohexylamine and dicyclohexylamine, and the yield of cyclohexylamine and dicyclohexylamine in the product is controlled by adjusting the water content in the raw materials.

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

[0029] Preferably, when the desired 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 0.1 wt%-1 wt% 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 aniline is 1 wt%-2 wt% 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 aniline is 2 wt%-3 wt% 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 this invention are as follows:

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

[0033] 2) The high total yield of cyclohexylamine and dicyclohexylamine is due to two factors: firstly, the catalyst used in this invention has high hydrogenation activity, resulting in low contents of byproducts cyclohexanol and N-cyclohexylenecyclohexylamine; secondly, it does not require adjusting the contents of cyclohexylamine and dicyclohexylamine by increasing the temperature, resulting in low contents of byproducts benzene and cyclohexane, and a total yield of cyclohexylamine and dicyclohexylamine exceeding 98%. Detailed Implementation

[0034] The present invention will be further illustrated below with specific embodiments. These embodiments are merely illustrative and do not limit the scope of the invention.

[0035] Unless otherwise specified, the raw materials and reagents used in the following examples and comparative examples were all purchased through commercial channels.

[0036] The gas chromatography analysis conditions in the following examples were as follows: Agilent DB-5 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 temperature program was 50°C held for 2 min, then increased to 80°C at 5°C / min, and then increased to 280°C at 15°C / min and held for 10 min.

[0037]

Example 1

[0038] Catalyst preparation:

[0039] 71.3g of Na₂CO₃ was dissolved in 672.6g of deionized water to prepare solution A. 45.5g of calcium nitrate monohydrate, 81.6g of cobalt nitrate hexahydrate, 1.9g of nickel nitrate hexahydrate, 1.0g of strontium nitrate, 2.7g of zinc nitrate hexahydrate, and 1.9g of copper nitrate monohydrate were dissolved in 523.8g of deionized water to prepare solution B. The water bath temperature was controlled at 70℃. Solutions A and B were simultaneously added dropwise to a three-necked flask containing 100g of deionized water with continuous stirring. After the addition was complete, the mixture was aged for 10 hours. The precipitate was then filtered and washed with deionized water until the pH reached 7. The mixture was dried at 110℃ for 18 hours and calcined at 400℃ in air for 6 hours to obtain the catalyst Cat-1 of this invention.

[0040]

Example 2

[0041] Catalyst preparation:

[0042] 65.4g of NaOH was dissolved in 1635.9g of deionized water to prepare solution A. 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 were weighed and dissolved in 641.6g of deionized water to prepare solution B. The water bath temperature was controlled at 70℃. Solutions A and B were simultaneously added dropwise to a three-necked flask containing 100g of deionized water with continuous stirring. After the addition was complete, the mixture was aged for 10 hours. The precipitate was then filtered and washed with deionized water until the pH reached 7. The mixture was dried at 120℃ for 24 hours and calcined at 500℃ in air for 5 hours to obtain the catalyst Cat-2 of this invention.

[0043]

Example 3

[0044] 50 g of the catalyst Cat-1 prepared in Example 1 was loaded into a fixed-bed reactor and activated at 350 °C and 100 kPaG for 24 h. After activation, aqueous aniline (with a water content of 0.1% by mass of aniline) and hydrogen were mixed, controlling the molar ratio of hydrogen to aniline to be 10. The mixture was preheated to 160 °C and then introduced into the fixed-bed reactor. The reaction temperature was controlled at 170 °C, the pressure at 150 kPaG, and the aniline mass hourly space velocity at 0.4 g. 苯胺 / (g cat The reaction mixture was prepared by gas chromatography (GC) and the resulting cyclohexylamine solution was analyzed. 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 example and Example 2 is that the water content is 1% of the mass of aniline, while the other conditions are the same as in Example 2. Analysis of the reaction solution showed that the aniline conversion rate was 100%, the cyclohexylamine yield was 94.1%, and the dicyclohexylamine yield was 5.4%.

[0047]

Example 5

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

[0049]

Example 6

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

[0051]

Example 7

[0052] 50 g of the catalyst Cat-2 prepared in Example 2 was loaded into a fixed-bed reactor and activated at 400 °C and 200 kPaG for 48 h. After activation, aqueous aniline (with a water content of 0.5% by mass of aniline) and hydrogen were mixed, controlling the molar ratio of hydrogen to aniline to be 10. The mixture was preheated to 160 °C and then introduced into the fixed-bed reactor. The reaction temperature was controlled at 170 °C, the pressure at 150 kPaG, and the aniline mass hourly space velocity at 0.4 g. 苯胺 / (g cat The reaction mixture was prepared by gas chromatography (GC) and the resulting cyclohexylamine solution was analyzed. 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 example and Example 7 is that the water content is 1.5% of the aniline mass, while the other conditions are the same as in Example 7. Analysis of the reaction solution showed that the aniline conversion rate was 100%, the cyclohexylamine yield was 90.3%, and the dicyclohexylamine yield was 8.9%.

[0055]

Example 9

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

[0057] Comparative Example 1

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

[0059] Comparative Example 2

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

[0061] The above description is only a preferred embodiment of the present invention. It should be noted that those skilled in the art can make several improvements and additions without departing from the method of the present invention, and these improvements and additions should also be considered within 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 hydrogenation reaction of aniline and hydrogen in the presence of a catalyst. The raw materials also contain water, with the water content ranging from 0.1 wt% to 3.0 wt% of the mass of aniline. The catalyst is a cobalt and nickel supported catalyst; the catalyst includes Co3O4 and NiO and an auxiliary agent, which is an alkaline earth metal oxide and a transition metal oxide; 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. The water and aniline are mixed first and then reacted, or a mixture of aniline and water with the above-mentioned water content is obtained during the preparation of aniline.

2. The preparation method according to claim 1, characterized in that, The reaction was carried out in a fixed-bed reactor.

3. The preparation method according to claim 1, characterized in that, The catalyst is supported by CaCO3 or Ca(OH)2.

4. The preparation method according to claim 1, characterized in that, In the catalyst, the mass content of Co3O4 is 40-45 wt%, the mass content of NiO is 0.5-2%, the mass content of the additive is 0.5-7 wt%, and the mass content of the support is 46-59 wt%.

5. The preparation method according to claim 1, characterized in that, The mass content of the alkaline earth metal oxide is 0.01-2 wt%, and the mass content of the transition metal oxide is 0.01-5 wt%.

6. The preparation method according to claim 5, characterized in that, The alkaline earth metal oxide has a mass content of 0.5-2 wt%, and the transition metal oxide has a mass content of 0.5-5 wt%.

7. The preparation method according to claim 1, characterized in that, The catalyst is prepared by: preparing a mixed solution containing calcium, Co, Ni and an auxiliary metal salt; adding the mixed solution and precipitant to a water-containing container at a temperature of 60-80℃ and stirring continuously; aging for 8-12 hours; then filtering and washing the precipitate with water; and drying and calcining to obtain the catalyst.

8. The preparation method according to claim 7, characterized in that, The precipitant is a sodium or potassium hydroxide, carbonate, or bicarbonate.

9. The preparation method according to claim 7, characterized in that, The drying temperature is 100-120℃, and the drying time is 12-24 hours.

10. The preparation method according to claim 7, characterized in that, The roasting temperature is 400-650℃, and the roasting time is 4-6 hours.

11. The preparation method according to claim 7, characterized in that, Calcination is carried out in an air or oxygen atmosphere.

12. The preparation method according to claim 1, characterized in that, The catalyst is activated under hydrogen conditions before use.

13. The preparation method according to claim 12, characterized in that, The catalyst is activated at a temperature of 200-500℃, an activation pressure of 50-400 kPaG, and an activation time of 24-72 h.

14. The preparation method according to claim 1, characterized in that, The feed molar ratio of hydrogen to aniline is 10-15:1; the reaction is preheated to 150-180℃ and the reaction temperature is 170-190℃; the reaction pressure is 100-200 kPaG; and the feed mass hourly space velocity of aniline is 0.4-1 g aniline / (gcat·h).

15. A method for controlling the yield of dicyclohexylamine in a reaction of cyclohexylamine and dicyclohexylamine, wherein the yield of cyclohexylamine and dicyclohexylamine in the product is controlled by adjusting the water content in the raw materials.

16. The control method according to claim 15, characterized in that, When it is necessary to increase the yield of dicyclohexylamine in the product, the water content in the raw material should be increased; when it is necessary to decrease the yield of dicyclohexylamine, the water content in the raw material should be decreased.

17. The control method according to claim 15, characterized in that, When the desired 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. The yield of dicyclohexylamine in the product increases with the increase of water content.

18. The control method according to claim 15, characterized in that, When the water content in the raw material is 0.1 wt%-1 wt% of the aniline mass, the yield of cyclohexylamine in the reaction product is 89.0%-98.5%, and the yield of dicyclohexylamine is 1.0%-9.0%; when the water content in the aniline is 1 wt%-2 wt% of the aniline mass, the yield of cyclohexylamine in the reaction product is 81.0%-94.0%, and the yield of dicyclohexylamine is 5.0%-17.0%; when the water content in the aniline is 2 wt%-3 wt% of the aniline mass, the yield of cyclohexylamine in the reaction product is 70.0%-88.0%, and the yield of dicyclohexylamine is 11.0%-28.0%.