Process for the preparation of alkyl diamines

Abstract

The application relates to the field of catalytic amination, and discloses a preparation method of alkyl diamine, which comprises the following steps: under the condition that a supported nickel catalyst exists, alkyl diol, ammonia and hydrogen are subjected to an amination reaction; the alkyl is C6-C 13 The alkyl diamine yield of the method is high, the reaction process does not involve toxic substances, and the amination reaction can be carried out at a relatively mild temperature.

Description

Technical Field

[0001] This invention relates to the field of catalytic amination, and more specifically to a method for preparing an alkyl diamine. Background Technology

[0002] Long-chain diamines possess strong basicity and react with long-carbon diacids to produce long-carbon diacid amines, which are the main raw materials for synthesizing long-chain polyamides. Long-chain polyamides are widely used in the automotive, aerospace, and electronics industries. Long-chain nylons have excellent properties, wide applications, and high added value; however, due to complex process routes, harsh production conditions, numerous synthesis steps, and high costs, the production of long-chain nylons and high-temperature resistant nylons has long been virtually nonexistent.

[0003] Nylon 1212, made from dodecanediamine, has low water absorption and boasts advantages such as good dimensional stability, oil resistance, alkali resistance, abrasion resistance, chemical resistance, good transparency, and excellent toughness at low temperatures, making it a viable alternative to Nylon 11 and Nylon 12. In recent years, with the development and industrial restructuring of aerospace, automotive, textile, instrumentation, and medical equipment industries, the demand for Nylon 1212 has been continuously increasing, creating market opportunities for dodecanediamine. The industrialization of dodecanediamine in China started late; currently, only three companies in China—Zibo Guangtong Chemical Co., Ltd., Wuxi Xingda Nylon Co., Ltd., and Hubei Jusheng Technology Co., Ltd.—are capable of large-scale production. The main production process involves a two-step method: dehydration of high-carbon dibasic acid to prepare high-carbon dinitrile, followed by hydrogenation of the high-carbon dinitrile to prepare high-carbon diamine. This route suffers from low yield and high cost, severely hindering the development of Nylon 1212 materials.

[0004] The traditional synthesis process uses dodecanoic acid and ammonia as raw materials, and reacts them at 270-300°C in the presence of phosphoric acid or its salts or esters as catalysts to produce diammonium dodecanoic acid. Then, it is heated and dehydrated to produce crude dodecanoic acid dinitrile, which is then hydrogenated to prepare dodecanediamine.

[0005] The above traditional reaction processes involve high temperatures and the toxic substance dodecanedionitrile, and the reaction yield is relatively low. Summary of the Invention

[0006] The purpose of this invention is to overcome the problems of low reaction yield, generation of toxic alkyl dinitrile, and high reaction temperature in existing alkyl diamine preparation methods, and to provide a method for preparing alkyl diamines that features low reaction temperature, avoidance of toxic substances, and high reaction yield.

[0007] To achieve the above objectives, the present invention provides a method for preparing alkyl diamines, the method comprising: an amination reaction of an alkyl diol, ammonia, and hydrogen in the presence of a supported nickel catalyst; wherein the alkyl group is C6-C. 13 alkyl.

[0008] The method of this invention produces high yields of alkyl diamines, the reaction process does not involve toxic substances, and the amination reaction can be carried out at a relatively mild temperature. Detailed Implementation

[0009] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0010] This invention provides a method for preparing alkyl diamines, comprising: an amination reaction of an alkyl diol, ammonia, and hydrogen in the presence of a supported nickel catalyst; wherein the alkyl group is C6-C. 13 alkyl.

[0011] According to a preferred embodiment of the present invention, the amination reaction is carried out in the presence of a solvent.

[0012] In this invention, the solvent can be any conventional choice in the art, as long as it achieves the objective of the invention. According to a preferred embodiment of the invention, the solvent is a hydroxyl-free solvent selected from one or more of tetrahydrofuran, cyclohexane, toluene, and benzene. By adopting the aforementioned preferred solution, the selectivity of alkyl diamines can be further improved, and the generation of secondary amines and other byproducts can be avoided.

[0013] According to a preferred embodiment of the present invention, the method for preparing the alkyl diamine of the present invention includes the following steps:

[0014] (1) Add alkyl diol, optionally solvent and supported nickel catalyst to the reactor and purge the reactor with nitrogen;

[0015] (2) Ammonia and hydrogen are introduced sequentially, the temperature is raised, and an amination reaction is carried out at a certain stirring speed to obtain alkyl diamine.

[0016] According to a preferred embodiment of the present invention, the alkyl group is C8-C. 12 alkyl.

[0017] In this invention, as long as the objective of the invention can be achieved, there are no special requirements regarding the purity of the alkyl diol. According to a preferred embodiment of the invention, the purity of the alkyl diol is greater than 98 wt%, and the content of the alkyl diacid is less than 100 ppm. By adopting the aforementioned preferred embodiment, the yield of the alkyl diamine product can be further improved.

[0018] In this invention, as long as the objective of the invention can be achieved, there are no particular requirements on the mass ratio of the alkyl diol, solvent, and supported nickel catalyst. According to a preferred embodiment of the invention, the mass ratio of the alkyl diol, solvent, and supported nickel catalyst is 1:(1-5):(0.02-0.15). By adopting the aforementioned preferred embodiment, the conversion rate of alkyl diol and the selectivity of alkyl diamine can be further improved.

[0019] In this invention, as long as the objective of the invention can be achieved, there are no particular requirements for the molar ratio of ammonia to alkyl diol. According to a preferred embodiment of the invention, the molar ratio of ammonia to alkyl diol is (5-12):1. By adopting the aforementioned preferred embodiment, the selectivity of alkyl diamines can be further improved.

[0020] In this invention, the conditions for the amination reaction can be any conventional selection in the art, as long as the objective of this invention is achieved. According to a preferred embodiment of this invention, the conditions for the amination reaction include: a reaction temperature of 180–250°C and an initial hydrogen partial pressure of 1–5 MPa. By adopting the aforementioned preferred scheme, the conversion rate of alkyl diols can be further improved.

[0021] To further improve the conversion rate of alkyl diols, according to a preferred embodiment of the present invention, the conditions for the amination reaction further include: a stirring speed of 100-1000 rpm / min.

[0022] In this invention, there are no special requirements for the supported nickel catalyst as long as the objective of the invention can be achieved. According to a preferred embodiment of the invention, the supported nickel catalyst is activated with an activator before the amination reaction, the activation temperature is 5-30°C, and the activation time is 5-15 hours. By adopting the aforementioned preferred scheme, the conversion rate of alkyl diols and the selectivity of alkyl diamines can be further improved.

[0023] To further improve the conversion rate of alkyl diols and the selectivity of alkyl diamines, according to a preferred embodiment of the present invention, the activator is an alkaline solution selected from one or more of ammonia, sodium bicarbonate aqueous solution, sodium hydroxide aqueous solution and potassium hydroxide aqueous solution, preferably ammonia or sodium bicarbonate aqueous solution, and the concentration of the activator is 5-20 wt%.

[0024] According to a preferred embodiment of the present invention, a mixed solution of ammonia and sodium bicarbonate is more preferably provided, and the molar ratio of sodium bicarbonate to ammonia is (2-4):1.

[0025] According to a preferred embodiment of the present invention, the preparation method of the present invention involves reducing the supported nickel catalyst with hydrogen gas before carrying out the amination reaction.

[0026] In this invention, the conditions for the reduction treatment can be any conventional selection in the art, as long as the objective of the invention is achieved. According to a preferred embodiment of the invention, the conditions for the reduction treatment include: a reduction temperature of 180–320°C, a reduction time of 3–12 h, and a hydrogen pressure of 0.1–2.5 MPa. By adopting the aforementioned preferred scheme, the catalyst activity can be further improved, and the conversion rate of alkyl diols can be increased.

[0027] According to a preferred embodiment of the present invention, the supported nickel catalyst is one or more of Ni / ZnO / Al2O3, Ni / CuO / Al2O3, and Ni / Al2O3 catalyst.

[0028] In this invention, as long as the objective of the invention can be achieved, there are no special requirements for the content of the components in the supported nickel catalyst. According to a preferred embodiment of the invention, the supported nickel catalyst, by weight, has a Ni content of 20-40%, a ZnO or CuO content of 0-15%, and a support Al2O3 content of 45-80%. By adopting the aforementioned preferred embodiment, the conversion rate of alkyl diols and the selectivity of alkyl diamines can be further improved.

[0029] To further improve the conversion rate of alkyl diols and the selectivity of alkyl diamines, according to a preferred embodiment of the present invention, the Al2O3 carrier is in one or more of the following shapes: clover-shaped, honeycomb-shaped, and gear-shaped.

[0030] The present invention does not impose any special requirements on the preparation method of the supported nickel catalyst, which is a conventional technical choice in the field and will not be described in detail here.

[0031] According to a preferred embodiment of the present invention, in the preparation method, the yield of the alkyl diamine is greater than 90%.

[0032] The present invention will be further described below through specific embodiments, but the scope of the present invention is not limited to the scope covered by the embodiments. In the present invention, unless otherwise specified, all reagents used are commercially available.

[0033] Dodecanoic acid (Yangzi Petrochemical Qingjiang Petrochemical Co., Ltd., model DDA)

[0034] Tetrahydrofuran (Nanjing Chemical Reagent Co., Ltd., analytical grade)

[0035] Benzene (Nanjing Chemical Reagent Co., Ltd., analytical grade)

[0036] Cyclohexane (Nanjing Chemical Reagent Co., Ltd., analytical grade)

[0037] Decanediol (Sinopec Nanjing Chemical Research Institute Co., Ltd., model number NH-10)

[0038] Nonyl glycol (Sinopec Nanjing Chemical Research Institute Co., Ltd., model number NH-9)

[0039] Raney nickel catalyst (Johnson & Johnson Catalysts Ltd., model A-5000)

[0040] The method involved in this invention is as follows:

[0041] Dodecanoic acid is prepared by esterification followed by hydrogenation. The esterification temperature is 120℃ and the reaction time is 10 h. The hydrogenation temperature is 195℃ and the space velocity is 0.5 h⁻¹. -1 Hydrogenation pressure: 6 MPa. Yield: 97.89%.

[0042] Preparation method of supported nickel catalyst: Weigh appropriate amounts of nickel nitrate, copper nitrate, or zinc nitrate to prepare an aqueous solution, add the shaped alumina support to the aqueous solution, and impregnate overnight. Place the impregnated support in an oven and dry at 120-150℃ for 12 hours, and finally calcine it in a muffle furnace at 300-350℃ for 8-12 hours.

[0043] Dehydration catalyst: Weigh an appropriate amount of zinc nitrate to prepare an aqueous solution, add the shaped alumina support to the aqueous solution, and impregnate overnight. Place the impregnated support in an oven and dry at 120-150℃ for 12 hours, and finally calcine it in a muffle furnace at 400-450℃ for 8-12 hours.

[0044] Analytical method for alkyl diamine products: Analysis was performed using an Agilent 7890 gas chromatograph with a DB-1701 capillary column. The vaporizer temperature was 250℃, the detector temperature was 250℃, and the column temperature was maintained at 230℃ for 20 min.

[0045] Method for calculating the yield of alkyldiamine:

[0046]

[0047]

[0048] Alkyl diamine yield (%) = alkyl diol conversion × alkyl diamine selectivity (Equation 3)

[0049] In the formula:

[0050] C1: Amount of alkyl diols involved in the reaction (%);

[0051] C2: Amount of unreacted alkyl diols (%);

[0052] C3: The amount (%) of alkyl diamines consumed.

[0053] Example 1

[0054] A Ni / CuO / Al2O3 supported nickel catalyst (Ni content 30wt%, CuO content 12wt%, Al2O3 content 58wt%, gear-shaped support) was prepared by impregnation method, activated at 25℃ for 10h with 10wt% ammonia solution, and reduced at 300℃ for 10h under hydrogen at 0.1MPa.

[0055] 30g of dodecanediol (purity 99.10%, dodecyl diacid content 20ppm), 140g of tetrahydrofuran, and 3g of supported nickel catalyst were weighed and added to a reactor. The reactor was purged with nitrogen, and ammonia and hydrogen were introduced separately. The initial partial pressure of hydrogen was 1.5MPa, and the molar ratio of ammonia to dodecanediol was 8:1. The amination reaction was carried out at a reaction temperature of 210℃ and a stirring speed of 700rpm / min to obtain dodecanediamine.

[0056] The yield of dodecanediamine was 97.03%.

[0057] Example 2

[0058] A Ni / Al2O3 supported nickel catalyst (Ni content 40wt%, Al2O3 content 60wt%, support in honeycomb briquette form) was prepared by impregnation method, activated at 20℃ for 12h with 18wt% sodium bicarbonate aqueous solution, and reduced at 290℃ for 12h under hydrogen at 0.5MPa.

[0059] 30g of dodecanediol (purity 99.42%, dodecyl diacid content 15ppm), 140g of cyclohexane, and 4.5g of supported nickel catalyst were weighed and added to a reaction vessel. The reaction vessel was purged with nitrogen, and ammonia and hydrogen were introduced separately. The initial partial pressure of hydrogen was 2.5MPa, and the molar ratio of ammonia to dodecanediol was 9:1. The amination reaction was carried out at a reaction temperature of 200℃ and a stirring speed of 900rpm / min to obtain dodecanediamine.

[0060] The yield of dodecanediamine was 96.43%.

[0061] Example 3

[0062] A Ni / ZnO / Al2O3 supported nickel catalyst (Ni content 30wt%, ZnO content 15wt%, Al2O3 content 55wt%, clover-shaped support) was prepared by impregnation method, activated at 15℃ for 15h with 15wt% ammonia solution, and reduced at 300℃ for 10h under hydrogen at 0.1MPa.

[0063] 30g of dodecanediol (purity 99.24%, dodecyl diacid content 25ppm), 140g of benzene, and 3.6g of supported nickel catalyst were weighed and added to a reaction vessel. The reaction vessel was purged with nitrogen, and ammonia and hydrogen were introduced separately. The initial partial pressure of hydrogen was 2.5MPa, and the molar ratio of ammonia to dodecanediol was 9:1. The amination reaction was carried out at a reaction temperature of 200℃ and a stirring speed of 600rpm / min to obtain dodecanediamine.

[0064] The yield of dodecanediamine was 96.83%.

[0065] Example 4

[0066] Repeat Example 1, but replace the 10wt% ammonia solution in Example 1 with a mixed solution of 10wt% ammonia and sodium bicarbonate in decanediol. The molar ratio of sodium bicarbonate to ammonia is 3:1. All other treatment conditions are the same as in Example 1.

[0067] The yield of dodecanediamine was 97.85%.

[0068] Example 5

[0069] Repeat Example 1, but replace dodecanediol in Example 1 with decanediol (purity 99.16%, sebacic acid 24ppm), and keep all other treatment conditions the same as in Example 1.

[0070] The yield of sebacdiamine was 95.86%.

[0071] Example 6

[0072] Repeat Example 1, but replace dodecanediol in Example 1 with nonanediol (purity 99.26%, azelaic acid 23ppm), and keep all other treatment conditions the same as in Example 1.

[0073] The yield of nonadiamine was 96.56%.

[0074] Example 7

[0075] Repeat Example 1, but replace the dodecyl glycol (99.10% purity, 20ppm dodecyl diacid content) in Example 1 with dodecyl glycol (94.59% purity, 150ppm dodecyl diacid content), and keep all other processing conditions the same as in Example 1.

[0076] The yield of dodecanediamine was 89.69%.

[0077] Example 8

[0078] Repeat Example 1, with the same mass of dodecyl glycol added, and the molar ratio of ammonia to dodecyl glycol being 3:1. All other treatment conditions were the same as in Example 1.

[0079] The yield of dodecanediamine was 87.29%.

[0080] Example 9

[0081] Repeat Example 1, with the same mass of dodecyl diol added, an initial hydrogen partial pressure of 0.5 MPa, and other treatment conditions as in Example 1.

[0082] The yield of dodecanediamine was 80.59%.

[0083] Example 10

[0084] Example 1 was repeated, and a Ni / CuO / Al2O3 supported nickel catalyst (Ni content 18wt%, CuO content 20wt%, Al2O3 content 62wt%, clover-shaped support) was prepared by impregnation, replacing the Ni / CuO / Al2O3 supported nickel catalyst in Example 1. All other processing conditions were the same as in Example 1.

[0085] The yield of dodecanediamine was 84.25%.

[0086] Example 11

[0087] Example 1 was repeated, except that the supported nickel catalyst was not activated with an activator, and all other treatment conditions were the same as in Example 1.

[0088] The yield of dodecanediamine was 89.76%.

[0089] Example 12

[0090] Repeat Example 1, using an impregnation method to prepare a Ni / CuO / Al2O3 supported nickel catalyst (cylindrical support), replacing the Ni / CuO / Al2O3 supported nickel catalyst in Example 1. All other processing conditions were the same as in Example 1.

[0091] The yield of dodecanediamine was 80.29%.

[0092] Comparative Example 1

[0093] Weigh 30g of dodecanoic acid and 3g of dehydration catalyst and place them in a high-pressure reactor. Purge the reactor twice with nitrogen. Start stirring and gradually increase the temperature. Introduce ammonia gas intermittently until the reactor pressure no longer drops. Then, raise the temperature to 300℃ and react for 12 hours to obtain dodecanoic dinitrile with a yield of 80.15%.

[0094] 25 g of dodecanedionitrile and 2.5 g of Raney nickel catalyst were weighed, and hydrogen gas at 2.5 MPa was introduced. The reaction was carried out at 150 °C for 8 h to obtain dodecanediamine. The yield of dodecanediamine was 78.19%.

[0095] Dodecanedionitrile is a toxic substance.

[0096] Comparative Example 2

[0097] Example 1 was repeated, and the Cu / ZnO / Al2O3 catalyst was prepared by impregnation instead of the Ni / CuO / Al2O3 supported nickel catalyst in Example 1. All other processing conditions were the same as in Example 1.

[0098] The yield of dodecanediamine was 41.59%.

[0099] As can be seen from Examples 1-12 and Comparative Examples 1-2, the alkyl diamines prepared by the method of the present invention in Examples 1-11 have high yields, relatively mild reaction temperatures, and do not involve toxic substances such as dinitriles in the reaction process.

[0100] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A method for preparing an alkyl diamine, characterized in that, The method includes: (1) Add alkyl glycol, solvent and supported nickel catalyst to the reactor and purge the reactor with nitrogen; (2) Ammonia and hydrogen are introduced sequentially, the temperature is raised, and the amination reaction is carried out under stirring; The alkyl group is C6-C. 13 alkyl; The supported nickel-based catalyst is one or more of Ni / ZnO / Al2O3, Ni / CuO / Al2O3, and Ni / Al2O3 catalyst; Before the amination reaction, the supported nickel catalyst is activated with an activator selected from one or more of ammonia, sodium bicarbonate aqueous solution, sodium hydroxide aqueous solution and potassium hydroxide aqueous solution, with a concentration of 5-20 wt%; the activation temperature is 5-30℃ and the activation time is 5-15 h.

2. The preparation method according to claim 1, wherein, The solvent is a solvent that does not contain hydroxyl groups.

3. The preparation method according to claim 2, wherein, The solvent is selected from one or more of tetrahydrofuran, cyclohexane, toluene, and benzene.

4. The preparation method according to claim 1, wherein, The alkyl group is C8-C. 12 Alkyl groups; and / or The alkyl diol has a purity greater than 98 wt%, and the alkyl diic acid content in the alkyl diol is less than 100 ppm.

5. The preparation method according to claim 1, wherein, The mass ratio of the alkyl diol, solvent, and supported nickel catalyst is 1:(1-5):(0.02-0.15); and / or The molar ratio of ammonia to alkyl diol is (5-12):

1.

6. The preparation method according to claim 1, wherein, The conditions for the amination reaction include: a reaction temperature of 180~250℃; and / or The initial partial pressure of hydrogen is 1~5 MPa; and / or The stirring speed is 100-1000 rpm / min.

7. The preparation method according to claim 1, wherein, The activator is ammonia or sodium bicarbonate aqueous solution.

8. The preparation method according to claim 7, wherein, The activator is a mixed solution of ammonia and sodium bicarbonate, and the molar ratio of sodium bicarbonate to ammonia is (2-4):

1.

9. The preparation method according to claim 1, wherein, Prior to the amination reaction, the supported nickel catalyst is reduced with hydrogen gas under the following conditions: a reduction temperature of 180–320 °C; and / or The restoration time is 3~12 hours; and / or The hydrogen pressure is 0.1~2.5MPa.

10. The preparation method according to claim 1, wherein, The supported nickel-based catalyst, by weight, has a Ni content of 20-40%, a ZnO or CuO content of 0-15%, and a support Al2O3 content of 45-80%; and / or The Al2O3 carrier has one or more shapes, such as clover-shaped, honeycomb-shaped, and gear-shaped.

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