A method for producing aminododeconitrile from laurolactam

Abstract

This invention provides a method for producing aminododecanoic acid from laurolactam. The method includes reacting ammonia and a laurolactam solution under a composite catalyst to obtain a product containing aminododecanoic acid. This method uses laurolactam as a raw material and directly produces aminododecanoic acid through high-temperature alkaline ring-opening under the action of a composite catalyst, while simultaneously yielding high-value-added aminododecanoic acid. Furthermore, the product can be promptly removed, avoiding system blockage caused by overheating and coking, thus improving economic efficiency and making it suitable for industrial production.

Description

Technical Field

[0001] This invention belongs to the field of organic synthesis technology and relates to a method for producing aminododecylonitrile from laurolactam. Background Technology

[0002] Nylon (Polyamide, abbreviated as PA) refers to plastics composed of polyamide resins. Long-chain nylon is a type of specialty nylon, generally referring to nylon materials with more than 10 methylene groups in the molecular chain. Due to its higher number of methylene groups, it has greater flexibility and suppleness. In addition, the reduced density of amide groups on the chain significantly reduces its hydrophilicity, improving its dimensional stability. Main varieties include PA12, PA1212, PA1012, and PA612, with PA12 having the highest market share, accounting for approximately 50% of the total specialty nylon market. It is an important engineering plastic. PA12 has advantages such as low water absorption, good low-temperature resistance, dimensional stability, and high toughness, and is mainly used in automobiles, communications, and as oil and gas pipelines.

[0003] US3705152 discloses a method for preparing 1,1'-dicyclohexyl peroxide (PXA) from cyclohexanone. PXA is then pyrolyzed to yield cyano-undecanoic acid (55% yield), cyclohexanone (16% yield), and caprolactam (10%), with a total yield of only 81%. Cyano-undecanoic acid is hydrogenated to obtain aminododecanoic acid, which is further polymerized to obtain PA12. However, the production process produces many byproducts, making purification difficult.

[0004] Baling Petrochemical disclosed a method for synthesizing cyanoundecanoic acid via high-temperature pyrolysis of 1,1'-dicyclohexyl peroxide. The pyrolysis temperature is 370–520 °C, and the ratio of deionized water to 1,1'-dicyclohexyl peroxide is 3:1. This method eliminates the need for pyrolysis under negative pressure, achieving a 11-cyanoundecanoic acid yield of up to 57%. However, the overall yield of the three products (11-cyanoundecanoic acid + cyclohexanone + caprolactam) is only 75%, and the pyrolysis process produces numerous byproducts, making subsequent product separation complex.

[0005] Therefore, in the existing cyclohexanone process, the production of PA12 intermediate cyanoundecanoic acid by PXA pyrolysis suffers from problems such as low yield, easy coking, and difficulty in continuous production. There is an urgent need to develop a low-cost, simple, and continuous production process for PA12 intermediate. Summary of the Invention

[0006] The purpose of this invention is to provide a method for producing aminododeconitrile from laurolactam, which directly produces aminododeconitrile by high-temperature alkaline ring-opening of laurolactam. This method can greatly simplify the production process and achieve continuous production, while reducing production costs and achieving higher raw material economy.

[0007] To achieve this objective, the present invention adopts the following technical solution:

[0008] This invention provides a method for producing aminododecylonitrile from laurolactam, the method comprising:

[0009] Ammonia and laurolactam solution react under a composite catalyst to obtain a product containing aminododecanoic acid.

[0010] The method described in this invention uses laurolactam as a raw material, and performs high-temperature alkaline ring-opening hydrolysis to produce aminododecanoic acid under the action of a composite catalyst. The aminododecanoic acid is then hydrogenated to obtain aminododecanoic acid, which is further polymerized to obtain PA12. Furthermore, the method utilizes a pyrolysis reaction under the action of a composite catalyst, improving the raw material conversion rate and product selectivity. Simultaneously, the produced aminododecanoic acid product is stable, the yield of the target product is significantly improved, and the coking problem common in traditional high-temperature pyrolysis processes is avoided, making it suitable for industrial production.

[0011] As a preferred technical solution of the present invention, the molar ratio of ammonia to laurolactam is (10-20):1, for example, it can be 11:1, 12:1, 13:1, 14:1, 15:1, 16:1, 17:1, 18:1 or 19:1, etc., but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0012] As a preferred embodiment of the present invention, the ammonia gas is preheated and then mixed with laurolactam solution before reacting.

[0013] Preferably, the temperature of the ammonia gas after preheating is 100-300℃, for example, it can be 120℃, 140℃, 150℃, 170℃, 190℃, 200℃, 220℃, 240℃, 250℃, 270℃ or 290℃, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0014] It is worth noting that in this invention, ammonia is preheated by a preheater, and the hot ammonia is used to bring laurolactam to the vaporization temperature in a timely manner, thereby improving the reaction efficiency.

[0015] As a preferred technical solution of the present invention, the mass fraction of the laurolactam solution is 20% to 50%, for example, it can be 22%, 24%, 25%, 26%, 28%, 30%, 32%, 34%, 35%, 36%, 38%, 40%, 42%, 44%, 45%, 46%, 48%, or 49%, etc., but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0016] As a preferred embodiment of the present invention, the laurolactam solution comprises laurolactam and an organic solvent.

[0017] Preferably, the organic solvent includes any one or a combination of at least two of methanol, ethanol, toluene, ethylbenzene or cyclohexane, wherein typical but non-limiting combinations are: a combination of methanol and ethanol, a combination of ethanol and toluene, a combination of toluene and ethylbenzene or a combination of ethylbenzene and cyclohexane, etc.

[0018] As a preferred embodiment of the present invention, the space velocity of the composite catalyst is 0.2–5 h⁻¹. -1 For example, it could be 0.5h -1 0.7h -1 1h -1 1.5h -1 2h -1 2.5h -1 3h -1 3.5h -1 4h -1 Or 4.5h -1 The values ​​are not limited to those listed; other unlisted values ​​within the range also apply.

[0019] The space velocity of the composite catalyst described in this invention refers to the mass space velocity of the composite catalyst.

[0020] Preferably, the composite catalyst comprises a first catalyst and a second catalyst.

[0021] Preferably, the mass ratio of the first catalyst to the second catalyst is 1:(1 to 5), for example, it can be 1:1.5, 1:2, 1:2.5, 1:3, 1:3.5, 1:4 or 1:4.5, etc., but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0022] It is worth noting that the composite catalyst used in this invention can further improve the raw material conversion rate and product selectivity compared to using aluminum oxide alone.

[0023] Preferably, the first catalyst is aluminum oxide.

[0024] Preferably, the second catalyst comprises any one or a combination of at least two of aluminum phosphate, boron phosphate, MCM-41 (molecular sieve), MCM22 (molecular sieve), HY (molecular sieve), or Beta zeolite, wherein typical but non-limiting combinations include: a combination of aluminum phosphate and boron phosphate, a combination of boron phosphate and MCM-41, a combination of MCM22 and HY, or a combination of Beta zeolite and boron phosphate, etc.

[0025] As a preferred embodiment of the present invention, the preparation method of the composite catalyst includes:

[0026] The first and second catalysts were mixed and then ball-milled. They were then mixed with stabilizers and sol, and then shaped and calcined in sequence to obtain the composite catalyst.

[0027] Preferably, the rotational speed of the ball mill is 350 to 450 r / min, for example, it can be 370 r / min, 390 r / min, 400 r / min, 410 r / min, 430 r / min or 440 r / min, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0028] Preferably, the stabilizer comprises polyethylene glycol.

[0029] Preferably, the amount of stabilizer added is 0.8% to 1.5% of the total mass of the first catalyst and the second catalyst, for example, it can be 0.9%, 1%, 1.1%, 1.2%, 1.3% or 1.4%, etc., but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0030] Preferably, the sol comprises silica sol and / or aluminum sol.

[0031] Preferably, the amount of sol added is 5% to 8% of the total mass of the first catalyst and the second catalyst, for example, it can be 5.5%, 6%, 6.5%, 7%, 7.5% or 7.9%, etc., but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0032] Preferably, the heating rate of the calcination is 3 to 8 °C / min, for example, it can be 4 °C / min, 5 °C / min, 6 °C / min or 7 °C / min, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0033] Preferably, the calcination temperature rise endpoint is 300-500℃, for example, it can be 320℃, 340℃, 350℃, 370℃, 390℃, 400℃, 420℃, 440℃, 450℃, 470℃ or 490℃, etc., but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0034] Preferably, the calcination holding time is 3 to 4 hours, for example, it can be 3.1 hours, 3.2 hours, 3.3 hours, 3.4 hours, 3.5 hours, 3.6 hours, 3.7 hours, 3.8 hours or 3.9 hours, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0035] In this invention, the molding method is not specifically limited, and conventional methods in the art can be used. The present invention involves calcining the molded composite catalyst to remove stabilizers and residual organic matter, allowing the sol to form materials such as alumina or silicates.

[0036] As a preferred embodiment of the present invention, the reaction is carried out in a fixed-bed reactor.

[0037] Preferably, the composite catalyst is packed in a fixed-bed reactor.

[0038] Preferably, the reaction is an alkaline ring-opening reaction.

[0039] Preferably, the reaction temperature is 250–350°C, for example, 260°C, 270°C, 280°C, 290°C, 300°C, 310°C, 320°C, 330°C, or 340°C, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0040] In this invention, the reaction can be carried out under normal pressure conditions.

[0041] As a preferred embodiment of the present invention, the product comprises aminododeconitrile and aminododeconitrile amide.

[0042] In this invention, the products include aminododeconitrile and aminododecamide. The present invention does not specifically limit the method for separating the two, and those skilled in the art can choose the appropriate technical means according to actual needs.

[0043] Preferably, the selectivity of the aminododecanoic acid is ≥63 mol.%, for example, it can be 65 mol.%, 67 mol.%, 70 mol.%, 72 mol.%, or 75 mol.%, etc., but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0044] As a preferred technical solution of the present invention, the method includes:

[0045] A laurolactam solution and preheated ammonia gas were introduced into a fixed-bed reactor packed with a composite catalyst, with the composite catalyst space velocity ranging from 0.2 to 5 h⁻¹. -1 The reaction was carried out at a temperature of 250–350 °C to obtain aminododeconitrile and aminododecamide.

[0046] The molar ratio of ammonia to laurolactam is (10-20):1; the temperature of the ammonia after preheating is 100-300℃; and the mass fraction of the laurolactam solution is 20%-50%.

[0047] The composite catalyst includes a first catalyst and a second catalyst; the mass ratio of the first catalyst and the second catalyst is 1:(1-5); the first catalyst is aluminum oxide; the second catalyst includes any one or a combination of at least two of aluminum phosphate, boron phosphate, MCM-41, MCM22, HY or Beta zeolite.

[0048] The preparation method of the composite catalyst includes: mixing the first catalyst and the second catalyst and then ball milling them, then mixing them with a stabilizer and a sol, and then successively molding and calcining them.

[0049] The numerical range described in this invention includes not only the point values ​​listed above, but also any point values ​​within the numerical ranges not listed above. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific point values ​​included in the range.

[0050] Compared with the prior art, the present invention has the following beneficial effects:

[0051] (1) The method provided by the present invention uses laurolactam as raw material and directly produces aminododecanoic acid by high-temperature alkaline ring opening under the action of composite catalyst, which can simultaneously obtain high-value-added aminododecanoic acid; and the product can be discharged in time to avoid system blockage caused by overheating and coking, thus improving economic efficiency.

[0052] (2) The method provided by this invention has low cost, simple process flow, and continuous production capability, and the conversion rate of laurolactam is ≥67 mol.% and the selectivity of aminododeconitrile is ≥63 mol.%. Attached Figure Description

[0053] Figure 1 This is a schematic diagram of the apparatus for producing aminododecanoic acid from laurolactam provided by the present invention.

[0054] Figure 2 The reaction formula for the production of aminododecylonitrile from ammonia and laurolactam provided by the present invention;

[0055] Among them, 1-preheater, 2-fixed bed reactor, 3-condenser, 4-collection tank, 5-composite catalyst. Detailed Implementation

[0056] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0057] This invention provides an apparatus for producing aminododecylnitrile from laurolactam, the schematic diagram of which is shown below. Figure 1 As shown, the device includes a preheater 1, a fixed-bed reactor 2, a condenser 3, and a receiving tank 4 connected in sequence;

[0058] The preheater 1 is provided with an ammonia inlet;

[0059] The bottom of the fixed-bed reactor 2 is provided with a raw material inlet;

[0060] The fixed-bed reactor 2 is filled with a composite catalyst 5.

[0061] This invention also provides a method for producing aminododeconitrile from laurolactam, the reaction formula of which is as follows: Figure 2 As shown, the method includes:

[0062] A laurolactam solution and preheated ammonia gas were introduced into a fixed-bed reactor packed with a composite catalyst, with the composite catalyst space velocity ranging from 0.2 to 5 h⁻¹. -1 The reaction was carried out at a temperature of 250–350 °C to obtain aminododeconitrile and aminododecamide.

[0063] The molar ratio of ammonia to laurolactam is (10-20):1; the temperature of the ammonia after preheating is 100-300℃; and the mass fraction of the laurolactam solution is 20%-50%.

[0064] The composite catalyst includes a first catalyst and a second catalyst; the mass ratio of the first catalyst and the second catalyst is 1:(1-5); the first catalyst is aluminum oxide; the second catalyst includes any one or a combination of at least two of aluminum phosphate, boron phosphate, MCM-41, MCM22, HY or Beta zeolite.

[0065] The preparation method of the composite catalyst includes: mixing the first catalyst and the second catalyst and then ball milling them, then mixing them with a stabilizer and a sol, and then successively molding and calcining them.

[0066] In the following examples and comparative examples, all aluminum oxide is γ-phase aluminum oxide.

[0067] Example 1

[0068] This embodiment provides a method for producing aminododecanoic acid from laurolactam, the reaction formula of which is as follows: Figure 2 As shown, the method includes:

[0069] A 30% laurolactam solution and high-purity ammonia gas preheated to 200°C were introduced into a fixed-bed reactor packed with a composite catalyst and allowed to remain for 2 hours at a catalyst space velocity of 1 h⁻¹. -1 The reaction was carried out at a temperature of 300℃ to obtain aminododeconitrile and aminododecanoic acid;

[0070] The molar ratio of ammonia to laurolactam is 15:1; the feed rate of ammonia is 33.6 L / h; the laurolactam solution comprises laurolactam and toluene; the feed rate of the laurolactam solution is 32 g / h.

[0071] The composite catalyst comprises aluminum oxide and aluminum phosphate in a mass ratio of 1:3;

[0072] The preparation method of the composite catalyst includes: mixing aluminum oxide and aluminum phosphate and then ball milling at a speed of 420 r / min, then mixing with polyethylene glycol and aluminum sol, and then molding and calcining at a temperature of 5℃ / min to 400℃ for 3.5 h.

[0073] The amount of polyethylene glycol added is 1% of the total mass of aluminum oxide and aluminum phosphate; the amount of aluminum sol added is 6.5% of the total mass of aluminum oxide and aluminum phosphate.

[0074] Example 2

[0075] This embodiment provides a method for producing aminododecanoic acid from laurolactam, the method comprising:

[0076] A 30% laurolactam solution and high-purity ammonia gas preheated to 200°C were introduced into a fixed-bed reactor packed with a composite catalyst and allowed to remain for 1 hour. The space velocity of the composite catalyst was 1 h⁻¹. -1 The reaction was carried out at a temperature of 300℃ to obtain aminododeconitrile and aminododecanoic acid;

[0077] The molar ratio of ammonia to laurolactam is 20:1; the feed rate of ammonia is 44.8 L / h; the laurolactam solution comprises laurolactam and toluene; the feed rate of the laurolactam solution is 65 g / h.

[0078] The composite catalyst comprises aluminum oxide and boron phosphate in a mass ratio of 1:1;

[0079] The preparation method of the composite catalyst includes: mixing aluminum oxide and boron phosphate and then ball milling at a speed of 420 r / min, then mixing with polyethylene glycol and aluminum sol, molding and calcining at a heating rate of 5℃ / min to 300℃ for 4h to obtain the catalyst.

[0080] The amount of polyethylene glycol added is 0.9% of the total mass of aluminum oxide and boron phosphate; the amount of aluminum sol added is 5% of the total mass of aluminum oxide and boron phosphate.

[0081] Example 3

[0082] This embodiment provides a method for producing aminododecanoic acid from laurolactam, the method comprising:

[0083] A 20% laurolactam solution and high-purity ammonia gas preheated to 200°C were introduced into a fixed-bed reactor packed with a composite catalyst and allowed to remain for 2 hours at a catalyst space velocity of 2 h⁻¹. -1 The reaction was carried out at a temperature of 300℃ to obtain aminododeconitrile and aminododecanoic acid;

[0084] The molar ratio of ammonia to laurolactam is 15:1; the feed rate of ammonia is 33.6 L / h; the laurolactam solution comprises laurolactam and toluene; the feed rate of the laurolactam solution is 32 g / h.

[0085] The composite catalyst comprises aluminum oxide and aluminum phosphate in a mass ratio of 1:5;

[0086] The preparation of the composite catalyst is the same as in Example 1.

[0087] Example 4

[0088] This embodiment provides a method for producing aminododecanoic acid from laurolactam, the method comprising:

[0089] A 50% laurolactam solution and high-purity ammonia gas preheated to 200°C were introduced into a fixed-bed reactor packed with a composite catalyst and held for 1.7 h at a catalyst space velocity of 1.7 h⁻¹. -1 The reaction was carried out at a temperature of 250℃ to obtain aminododeconitrile and aminododecamide;

[0090] The molar ratio of ammonia to laurolactam is 15:1; the feed rate of ammonia is 33.6 L / h; the laurolactam solution comprises laurolactam and toluene; the feed rate of the laurolactam solution is 40 g / h.

[0091] The composite catalyst is aluminum oxide and Beta zeolite in a mass ratio of 1:3;

[0092] The preparation method of the composite catalyst includes: mixing alumina and Beta zeolite and then ball milling at a speed of 400 r / min, then mixing with polyethylene glycol and aluminum sol, molding, and calcining at a heating rate of 5℃ / min to 500℃ for 3h.

[0093] The amount of polyethylene glycol added is 1.5% of the total mass of aluminum oxide and Beta zeolite; the amount of aluminum sol added is 8% of the total mass of aluminum oxide and Beta zeolite.

[0094] Example 5

[0095] This embodiment provides a method for producing aminododeconitrile from laurolactam. Except for the temperature of 100°C after preheating with high-purity ammonia, all other conditions are the same as in Example 1.

[0096] Example 6

[0097] This embodiment provides a method for producing aminododeconitrile from laurolactam. Except for the temperature of 70°C after preheating with high-purity ammonia, all other conditions are the same as in Example 1.

[0098] Example 7

[0099] This embodiment provides a method for producing aminododecanoic acid from laurolactam. Except for the temperature of 400°C after preheating with high-purity ammonia, all other conditions are the same as in Example 1.

[0100] Example 8

[0101] This embodiment provides a method for producing aminododecylonitrile from laurolactam. Except for the molar ratio of ammonia to laurolactam being 5:1, all other conditions are the same as in Example 1.

[0102] Example 9

[0103] This embodiment provides a method for producing aminododecylonitrile from laurolactam. Except for the molar ratio of ammonia to laurolactam being 30:1, all other conditions are the same as in Example 1.

[0104] Example 10

[0105] This embodiment provides a method for producing aminododecanoic acid from laurolactam. Except for the mass ratio of aluminum oxide to aluminum phosphate being 1:0.5, all other conditions are the same as in Example 1.

[0106] Example 11

[0107] This embodiment provides a method for producing aminododecylonitrile from laurolactam. Except for the mass ratio of aluminum oxide to aluminum phosphate being 1:7, all other conditions are the same as in Example 1.

[0108] Example 12

[0109] This embodiment provides a method for producing aminododecanoic acid from laurolactam. Except for the absence of aluminum sol in the preparation of the composite catalyst, all other conditions are the same as in Example 1.

[0110] Example 13

[0111] This embodiment provides a method for producing aminododecanoic acid from laurolactam. Except for the reaction temperature of 350°C, all other conditions are the same as in Example 1.

[0112] Example 14

[0113] This embodiment provides a method for producing aminododecanoic acid from laurolactam. Except for the reaction temperature of 200°C, all other conditions are the same as in Example 1.

[0114] Example 15

[0115] This embodiment provides a method for producing aminododecanoic acid from laurolactam. Except for the reaction temperature of 400°C, all other conditions are the same as in Example 1.

[0116] Comparative Example 1

[0117] This comparative example provides a method for producing aminododecanoic acid from laurolactam, except that the catalyst is aluminum oxide, and all other conditions are the same as in Example 1.

[0118] Comparative Example 2

[0119] This comparative example provides a method for producing aminododecanoic acid from laurolactam, except that the catalyst is aluminum phosphate, and all other conditions are the same as in Example 1.

[0120] The conversion rate of the raw material laurolactam and the selectivity of the products aminododeconitrile and aminododeconitrile were quantitatively analyzed by gas chromatography. The test results of the above examples and comparative examples are shown in Table 1.

[0121] Table 1

[0122]

[0123] As shown in Table 1:

[0124] (1) The method provided by the present invention directly produces aminododecanoic acid by high-temperature alkaline ring-opening of laurolactam, which has good raw material conversion rate and product selectivity, and the conversion rate of laurolactam is ≥67 mol.% and the selectivity of aminododecanoic acid is ≥63 mol.%.

[0125] (2) Comparison of Examples 1 and 6-7 shows that when the temperature of ammonia after preheating is too low, laurolactam cannot reach the vaporization temperature in time, resulting in a low conversion rate of laurolactam; when the temperature of ammonia after preheating is too high, the volume of the heated gas expands, resulting in a faster flow rate of ammonia carrier gas. When laurolactam comes into contact with ammonia, a ring-opening reaction will occur. Although this increases the conversion rate of laurolactam, the ammonia effect is worse and the selectivity of aminododeconitrile decreases because the residence time in the reactor is shortened.

[0126] (3) Comparing Example 1 and Example 8-9, it can be seen that when the molar ratio of ammonia to laurolactam is too low, the selectivity of the by-product aminododecylamide increases due to insufficient ammonia participating in the reaction; when the molar ratio of ammonia to laurolactam is too high, the conversion rate of laurolactam decreases due to the increased gas volume and excessive flow rate.

[0127] (4) A comparison of Examples 1 and 10-12, and Comparative Examples 1-2 shows that when the proportion of aluminum oxide in the composite catalyst is too high, the number of aluminum active sites increases, the amount of raw material ring opening increases, and the raw material conversion rate increases. However, the phosphorus active sites are insufficient, resulting in a poor ammoniation effect and a decrease in the selectivity of the target product, aminododecylonitrile. When the proportion of aluminum oxide in the composite catalyst is too low, the insufficient aluminum metal leads to a lower ring opening efficiency of laurolactam and a decrease in conversion rate. When aluminum sol is not added during the preparation of the composite catalyst, the catalyst strength is insufficient, leading to breakage, pulverization, and blockage of the reactor pipeline. When the catalyst is only aluminum oxide or aluminum phosphate, the insufficient aluminum and phosphorus active sites lead to a decrease in both raw material conversion rate and product selectivity.

[0128] (5) Comparing Example 1 and Example 14-15, it can be seen that when the reaction temperature is too low, the ammoniation temperature of laurolactam is not reached, resulting in only a small portion of the raw material undergoing ammoniation to generate aminododeconitrile after ring opening, while most of it generates aminododeconitrile. When the reaction temperature is too high, although the conversion rate of laurolactam will increase, the organic matter will carbonize, causing the material to coke on the catalyst surface and inside the reactor, thus clogging the reactor.

[0129] The applicant declares that the detailed structural features of the present invention are illustrated through the above embodiments, but the present invention is not limited to the above detailed structural features, that is, it does not mean that the present invention must rely on the above detailed structural features to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent substitutions for the components selected in the present invention, additions of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

[0130] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention.

[0131] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not describe the various possible combinations separately.

[0132] Furthermore, various different embodiments of the present invention can be combined in any way, as long as they do not violate the spirit of the present invention, they should also be regarded as the content disclosed by the present invention.

Claims

1. A method for producing aminododecanoic acid from laurolactam, characterized in that, The method includes: Ammonia and laurolactam solution reacted under a composite catalyst to yield a product containing aminododecanoic acid. The composite catalyst includes a first catalyst and a second catalyst; The mass ratio of the first catalyst to the second catalyst is 1:(1~5); The first catalyst is aluminum oxide; The second catalyst is any one or a combination of at least two of the following: aluminum phosphate, boron phosphate, MCM-41 molecular sieve, MCM22 molecular sieve, HY molecular sieve, or Beta zeolite; The preparation method of the composite catalyst includes: The first and second catalysts were mixed and then ball-milled. They were then mixed with stabilizers and sol, and then shaped and calcined in sequence to obtain the composite catalyst.

2. The method according to claim 1, characterized in that, The molar ratio of ammonia to laurolactam is (10~20):

1.

3. The method according to claim 1 or 2, characterized in that, The ammonia gas is preheated and then mixed with laurolactam solution before the reaction is carried out.

4. The method according to claim 3, characterized in that, The temperature of the ammonia gas after preheating is 100~300℃.

5. The method according to claim 1, characterized in that, The laurolactam solution has a mass fraction of 20% to 50%.

6. The method according to claim 1, characterized in that, The laurolactam solution comprises laurolactam and an organic solvent.

7. The method according to claim 6, characterized in that, The organic solvent is any one or a combination of at least two of methanol, ethanol, toluene, ethylbenzene or cyclohexane.

8. The method according to claim 1, characterized in that, The space velocity of the composite catalyst is 0.2~5h. -1 .

9. The method according to claim 1, characterized in that, The ball mill rotates at a speed of 350~450 r / min.

10. The method according to claim 1, characterized in that, The stabilizer is polyethylene glycol.

11. The method according to claim 1, characterized in that, The amount of stabilizer added is 0.8% to 1.5% of the total mass of the first catalyst and the second catalyst.

12. The method according to claim 1, characterized in that, The sol is a silica sol and / or an aluminum sol.

13. The method according to claim 1, characterized in that, The amount of sol added is 5% to 8% of the total mass of the first catalyst and the second catalyst.

14. The method according to claim 1, characterized in that, The heating rate for calcination is 3~8℃ / min.

15. The method according to claim 1, characterized in that, The calcination temperature rise endpoint is 300~500℃.

16. The method according to claim 1, characterized in that, The calcination holding time is 3-4 hours.

17. The method according to claim 1, characterized in that, The reaction is carried out in a fixed-bed reactor.

18. The method according to claim 17, characterized in that, The composite catalyst is packed in a fixed-bed reactor.

19. The method according to claim 1, characterized in that, The reaction is a base hydrolysis ring-opening reaction.

20. The method according to claim 1, characterized in that, The reaction temperature is 250~350℃.

21. The method according to claim 1, characterized in that, The products include aminododeconitrile and aminododecylamide.

22. The method according to claim 21, characterized in that, The selectivity of the aminododeconitrile is ≥63 mol.%.

23. The method according to claim 1, characterized in that, The method includes: Lauryl lactam solution and preheated ammonia gas were introduced into a fixed-bed reactor packed with a composite catalyst, with the composite catalyst space velocity being 0.2~5 h⁻¹. -1 The reaction was carried out at a temperature of 250~350℃ to obtain aminododeconitrile and aminododecamide; The molar ratio of ammonia to laurolactam is (10~20):1; the temperature of the ammonia after preheating is 100~300℃; the mass fraction of the laurolactam solution is 20%~50%. The composite catalyst includes a first catalyst and a second catalyst; the mass ratio of the first catalyst and the second catalyst is 1:(1~5); the first catalyst is aluminum oxide; the second catalyst is any one or a combination of at least two of aluminum phosphate, boron phosphate, MCM-41 molecular sieve, MCM22 molecular sieve, HY molecular sieve or Beta zeolite. The preparation method of the composite catalyst includes: mixing the first catalyst and the second catalyst and then ball milling them, then mixing them with a stabilizer and a sol, and then successively molding and calcining them.

Images