Method for preparing 6-aminocapronitrile by ammonolysis of caprolactam

Abstract

The invention discloses a method for preparing 6-aminocapronitrile from caprolactam through a one-step catalytic ammonolysis method, caprolactam and ammonia are used as raw materials, one-step efficient conversion is realized under the mild conditions of normal pressure and 200-350 DEG C through the innovative design of a composite oxide catalyst (main-auxiliary active components have a synergistic effect), the selectivity of a target product is greater than or equal to 99.5%, and the conversion rate is greater than or equal to 99%. Compared with the prior art, the method provided by the invention solves the core bottlenecks of fast catalyst deactivation (such as frequent replacement in CN107602416A operation), harsh reaction conditions (high temperature and high pressure), more byproducts and the like in a traditional process in a breakthrough manner, and has the advantages of short process flow, mild reaction conditions, environmental friendliness, high catalyst activity, good stability, high target product selectivity and the like; the method can realize one-step high-selectivity conversion of caprolactam into 6-aminocapronitrile, and has important industrial application prospects.

Description

Technical Field

[0001] The present invention relates to the technical field of preparation of 6-aminocapronitrile, and in particular to a method for preparing 6-aminocapronitrile by a one-step catalytic ammonolysis of caprolactam. Background Art

[0002] 1,6-Hexanediamine is an important chemical intermediate widely used in the production of nylon 66, nylon 610, polyurethane resins, and organic crosslinkers. Its industrial production routes can be categorized by raw material source into the adiponitrile method, the caprolactam method, the hexanediol method, and the adipaldehyde method. The caprolactam method is considered a highly promising process due to its short process flow, mild reaction conditions, and high safety profile. This method uses caprolactam and ammonia as raw materials, catalytically ammonolyzing them to produce 6-aminocapronitrile, which is then hydrogenated to produce hexanediamine. The specific reaction equation is as follows:

[0003]

[0004] Although the caprolactam method has significant advantages, the existing technology still has the following key issues that need to be solved:

[0005] (1) Catalyst preparation is complex and has poor stability

[0006] CN110404582A uses phosphorus aluminum molecular sieve to load active components such as magnesium nitrate and aluminum nitrate, which requires multiple roasting processes, resulting in a complicated process and high energy consumption;

[0007] CN111672494A prepares a composite catalyst by reacting silica hydrogel with aluminum salt, which involves two drying and calcination steps, significantly increasing production costs;

[0008] CN107602416A uses catalysts such as calcium oxide and iron oxide. Although the initial selectivity reaches 97%, the catalyst deactivates quickly and needs to be replaced frequently, which limits the continuity of industrialization.

[0009] (2) The reaction conditions are harsh, and energy consumption and pollution coexist

[0010] US3855267 requires a reaction temperature as high as 375°C and a molar ratio of ammonia to caprolactam of 75-100, resulting in high energy consumption and low raw material utilization;

[0011] CN113105362A requires a high temperature of 400°C and a pressure of 0.5 MPa in a fluidized bed reactor, which increases side reactions and makes product separation difficult.

[0012] Although the core-shell catalyst of CN111659374A improves the selectivity to 97%, the reaction temperature is high and the conversion rate is not high.

[0013] (3) Conflict between byproduct generation and selectivity

[0014] CN114192170A uses a high silicon aluminum phosphorus catalyst. Although it achieves a caprolactam conversion rate of 82.8-99.3% at 320°C, its catalyst requires a complex preparation process (containing P2O5) and the product purity is unstable;

[0015] In the gas phase method of CN111004148A, the reaction temperature needs to be 330-430°C, which causes thermal decomposition of part of the caprolactam to generate cyclic by-products, resulting in a loss in yield.

[0016] (4) Restrictions on large-scale production

[0017] Toray Industries, a Japanese company, had limited industrialization attempts due to the supply of raw materials. The attempts were only applicable to the recycling of waste nylon and could not meet the needs of large-scale continuous production.

[0018] CN111978207A uses a microchannel reactor. Although the conversion rate and selectivity are both over 99%, the equipment cost is high and the high temperature (400-550°C) process has strict requirements on the corrosion resistance of the material.

[0019] In summary, the existing caprolactam aminolysis methods generally have the following defects:

[0020] (1) Complex catalyst synthesis: multi-step calcination and loading processes result in long preparation cycles, high costs, and easy catalyst deactivation;

[0021] (2) Harsh reaction conditions: high temperature (350-550°C) and high pressure (0.5-1 MPa) increase energy consumption and increase side reactions;

[0022] (3) Unstable product selectivity: The proportion of by-products (such as cyclohexanone and caprolactam dimer) fluctuates, affecting product purity;

[0023] (4) Low industrial feasibility: high equipment requirements and insufficient raw material utilization make it difficult to achieve low-cost continuous production.

[0024] In response to the above technical problems, the present invention provides a method for preparing 6-aminocapronitrile by a one-step catalytic ammonolysis of caprolactam. The method has the advantages of a short process flow, mild reaction conditions, environmental friendliness, high catalyst activity and stability, and high selectivity for the target product. It can achieve a one-step, highly selective conversion of caprolactam to 6-aminocapronitrile, and has important industrial application prospects. Summary of the Invention

[0025] The present application aims to provide a method for preparing 6-aminocapronitrile by a one-step catalytic ammonolysis of caprolactam. This method uses caprolactam and ammonia as raw materials. By optimizing the reaction system and catalyst design, it achieves a one-step, highly selective conversion to 6-aminocapronitrile under mild process conditions. Compared to other hexamethylenediamine production routes, this method offers advantages such as a shorter process flow, mild reaction conditions, environmental friendliness, high catalyst activity and stability, and high selectivity for the target product, thus possessing significant industrial application prospects.

[0026] The present invention adopts the following technical solutions:

[0027] A method for preparing 6-aminocapronitrile by a one-step catalytic ammonolysis of caprolactam, comprising mixing caprolactam with ammonia, and carrying out an ammonolysis reaction under the action of a solid composite oxide catalyst to produce a 6-aminocapronitrile product in one step; the main active component of the solid composite oxide catalyst is selected from one or more of calcium, aluminum, magnesium, barium, strontium, titanium, zirconium, vanadium, niobium, chromium, molybdenum, tungsten, manganese, iron, zinc, copper, cobalt, nickel, antimony, bismuth, lanthanum, and cerium; and the auxiliary active component is selected from one or more of silicon, sulfur, selenium, boron, nitrogen, fluorine, phosphorus, arsenic, tellurium, and iodine, preferably AlPO x 、MgAlBO x 、ZnAsO x 、LaIO x 、BaWSO x 、VSO x 、CaMoPO x 、CaWPSO x Solid composite oxide catalysts.

[0028] Furthermore, the co-activating component accounts for 0.5-50 wt% of the total mass of the composite catalyst, preferably 1-45 wt%, more preferably 1.5-30 wt%, more preferably 2-25 wt%, more preferably 2.5-20 wt%.

[0029] Furthermore, the solvent of the caprolactam solution is selected from one or more of methanol, ethanol, tert-butanol, acetonitrile, benzene, toluene, and dioxane; preferably one or more of methanol, ethanol, and acetonitrile.

[0030] Furthermore, the mass concentration of the caprolactam solution is 5 to 100 wt %, preferably 10 to 60 wt %, and more preferably 20 to 40 wt %.

[0031] Furthermore, the molar ratio of ammonia to caprolactam is 10 to 300:1, preferably 50 to 250:1, and more preferably 100 to 200:1.

[0032] Furthermore, the ammonolysis reaction is carried out in a fixed bed, fluidized bed or trickle bed reactor, preferably a fixed bed reactor.

[0033] Furthermore, the temperature of the ammonolysis reaction is 100-380°C, preferably 150-350°C, and more preferably 200-350°C, which greatly reduces the heating cost compared with the prior art (generally >350°C); and avoids thermal decomposition of caprolactam, and significantly reduces the total amount of by-products.

[0034] Furthermore, the ammonolysis reaction can be carried out under normal pressure without the need for a high-pressure reactor, which significantly reduces equipment costs and significantly improves safety.

[0035] Furthermore, the ammonia is recovered and recycled for the reaction, with a tail gas recovery rate of ≥95%, and the raw material utilization rate is increased to about 1.5 times that of the traditional process.

[0036] The preparation methods of the above catalysts include but are not limited to sol-gel method, precipitation method, hydrothermal method, etc.

[0037] The sol-gel method specifically includes the following steps:

[0038] S1. In water and / or an organic solvent, a compound of the main active component is added to obtain a solution A;

[0039] S2. In an organic solvent and / or water, adding a co-active component compound and a hydrolysis inhibitor to obtain a solution B;

[0040] S3. Add liquid B dropwise to liquid A, stir to form a sol, and then age to obtain a gel.

[0041] S4. The gel obtained in step S3 was filtered and washed with deionized water until neutral to obtain a filter cake;

[0042] S5. Dry and calcine the filter cake obtained in step S4 to obtain a solid composite oxide catalyst.

[0043] Furthermore, the hydrolysis inhibitor is acetic acid and / or citric acid.

[0044] The above-mentioned precipitation method specifically comprises the following steps:

[0045] I. adding the main active component to water and / or an organic solvent to obtain solution A;

[0046] II. adding a precipitant to water and / or an organic solvent to obtain a solution B;

[0047] III. Liquid B is added dropwise to liquid A for precipitation reaction, and then a compound of the co-active component is added as a modifier, and then aged to obtain a solid precipitate;

[0048] IV. The solid precipitate obtained in step III was filtered and washed with deionized water until neutral to obtain a filter cake;

[0049] V. Dry and calcine the filter cake obtained in step IV to obtain a solid composite oxide catalyst.

[0050] Furthermore, the organic solvent is one or more of methanol, ethanol, n-propanol, isopropanol, tert-butanol, and ethylene glycol.

[0051] Furthermore, the precipitant is selected from at least one of urea, sodium carbonate, sodium bicarbonate, ammonium carbonate, ammonium bicarbonate, calcium hydroxide, ammonia water and sodium hydroxide.

[0052] Furthermore, the solid composite oxide catalyst is preferably a supported catalyst, and its carrier is selected from silica gel, alumina, molecular sieves, activated carbon, hydrotalcite and natural minerals, natural minerals such as sepiolite, diatomaceous earth, attapulgite, montmorillonite, etc., and the molecular sieve is preferably ZSM-5, HZSM-5, MCM-41, SBA-15, Y-type molecular sieve, mordenite, etc.; the active component accounts for 1 to 50% of the total mass of the supported catalyst, preferably 5 to 40%, and more preferably 10 to 30%.

[0053] Furthermore, the modifier containing the auxiliary active component is selected from one or more of silicic acid, sulfuric acid, phosphoric acid, arsenic acid, telluric acid, iodic acid, phosphotungstic acid and the like.

[0054] Furthermore, the aging temperature is 20-70°C, the aging time is 6-48h, preferably 12-36h; the drying temperature is 60-120°C, the drying time is 1-24h; the roasting temperature is 200-800°C, preferably 300-600°C; and the roasting time is 1-8h.

[0055] Compared with the prior art, the present invention has the following beneficial effects:

[0056] (1) Catalyst innovation: The present invention significantly improves catalytic performance through composite oxide design (synergistic effect of main and auxiliary active components), achieving a conversion rate ≥ 99% and a selectivity ≥ 99% under milder conditions (such as normal pressure and 300°C), which is significantly better than existing technologies.

[0057] (2) Breakthrough in stability: The catalyst has stable performance after 300 hours of operation, which solves the problem of rapid catalyst deactivation in the prior art (such as CN107602416A).

[0058] (3) Process simplification: One-step process, no need for multi-step reactions or complex post-processing. BRIEF DESCRIPTION OF THE DRAWINGS

[0059] Figure 1 This is a graph showing the stability test results of the catalyst of the present invention. DETAILED DESCRIPTION

[0060] The method of the present invention is described in detail below with reference to the embodiments, but the present invention is not limited thereto, and the relevant features of the present invention can be combined with each other.

[0061] Example 1: AlPO x Preparation of solid composite oxide catalysts

[0062] 82.7 g of aluminum isopropoxide was added to 200 g of isopropanol to obtain a mixed solution A; 34.6 g of phosphoric acid and 20.5 g of citric acid were added to a mixed solution of 67.5 g of isopropanol and 28.2 g of deionized water, and ultrasonic stirring was performed to obtain a mixed solution B; at 50 ° C, solution B was added dropwise to solution A, stirred to form a sol, aged at 50 ° C for 24 h to obtain a gel, then washed with deionized water until neutral, dried in a 110 ° C oven for 24 h, and finally calcined in a muffle furnace at 400 ° C for 2 h to obtain AlPO x Solid composite oxide catalyst.

[0063] Example 2: MgAlBO x Preparation of composite oxide catalysts

[0064] 61.3 g of magnesium methoxide and 26.4 g of aluminum sec-butoxide were added to 250 g of methanol to obtain a mixed solution A; 34.6 g of boric acid and 25.5 g of acetic acid were added to a mixed solution of 80.5 g of methanol and 30.1 g of deionized water, and ultrasonic stirring was performed to obtain a mixed solution B; at 65 ° C, solution B was added dropwise to solution A to form a sol under vigorous stirring, and aged at 65 ° C for 12 h to obtain a gel, which was then washed with deionized water until neutral, dried in an oven at 110 ° C for 12 h, and finally calcined in a muffle furnace at 500 ° C for 4 h to obtain MgAlBO x Composite oxide catalysts.

[0065] Example 3: ZnAsO x Preparation of solid composite oxide catalysts

[0066] Dissolve 32.5g of sodium carbonate and 40.8g of zinc nitrate hexahydrate in 450mL of deionized water and dissolve them by ultrasonication at 25°C. Transfer the evenly dissolved mixture to a 1000mL three-necked flask equipped with a thermometer and a mechanical stirring device. At 35°C, adjust the pH to about 9 with ammonia water, continue stirring for 2h, and age for 36h to obtain an aging solution. Filter the obtained aging solution with deionized water and wash it until it is neutral. Take the filter cake and dry it in an oven at 110°C for 24h to obtain dry particles. Disperse the particles in 300mL of deionized water, add arsenic acid modifier, stir for 2h, age at 35°C for 12h, dry in an oven at 110°C for 24h, and finally calcine at 350°C in a muffle furnace for 4h to obtain ZnAsO x Solid composite oxide catalyst.

[0067] Example 4: LaIO x Preparation of solid composite oxide catalysts

[0068] Dissolve 32.8g of urea and 47.3g of lanthanum nitrate hexahydrate in 300mL of deionized water and dissolve them by ultrasonication at 25°C. Transfer the evenly dissolved mixture to a 1000mL three-necked flask equipped with a condenser, thermometer, and mechanical stirring device. At 102°C, adjust the pH to about 9 with ammonia water, continue stirring for 2h, and age for 24h to obtain an aging solution. The obtained aging solution was filtered and washed with deionized water until it was neutral. The filter cake was dried in an oven at 110°C for 12h to obtain dry particles. The particles were dispersed in 200mL of deionized water, iodic acid modifier was added, stirred for 2h, aged at 35°C for 24h, dried in an oven at 110°C for 12h, and finally calcined at 700°C in a muffle furnace for 4h to obtain LaIO x Solid composite oxide catalyst.

[0069] Example 5: BaWSO x Preparation of solid composite oxide catalysts

[0070] Dissolve 56.4g of ammonium carbonate, 40.8g of barium chloride and 43.2g of ammonium metatungstate in 450mL of deionized water and dissolve them by ultrasonication at 25°C. Transfer the evenly dissolved mixture to a 1000mL three-necked flask equipped with a condenser, thermometer and mechanical stirring device. At 80°C, adjust the pH to about 9 with ammonia water, continue stirring for 2h, and age for 36h to obtain an aging solution. Filter the obtained aging solution with deionized water and wash it until it is neutral. Take the filter cake and dry it in a 110°C oven for 24h to obtain dry particles. Disperse the particles in 300mL of deionized water, add sulfuric acid modifier, stir for 2h, age at 35°C for 12h, dry in a 110°C oven for 24h, and finally calcine at 800°C in a muffle furnace for 6h to obtain BaWSO x Solid composite oxide catalyst.

[0071] Example 6: VSO x Preparation of solid composite oxide catalysts

[0072] Dissolve 37.9g of ammonium metavanadate and 68.8g of ammonia water in 350mL of deionized water and dissolve them by ultrasonication at 25°C. Transfer the evenly dissolved mixture to a 1000mL three-necked flask equipped with a thermometer and a mechanical stirring device, start stirring, heat in an oil bath until the temperature stabilizes to 40°C, continue stirring for 4h, and age for 12h to obtain an aging solution. The obtained aging solution is filtered and washed with deionized water until it becomes neutral. The filter cake is dried in an oven at 110°C for 24h to obtain dry particles. The particles are dispersed in 300mL of deionized water, sulfuric acid modifier is added, stirred for 2h, aged at room temperature for 12h, dried in an oven at 110°C for 24h, and finally calcined in a muffle furnace at 500°C for 2h to obtain VSO. x Solid composite oxide catalyst.

[0073] Example 7: CaMoPO x Preparation of composite oxide catalysts

[0074] Dissolve 36.4g of calcium hydroxide and 50.6g of ammonium molybdate in 400mL of deionized water and dissolve them by ultrasonication at 25°C. Transfer the evenly dissolved mixture to a 1000mL three-necked flask equipped with a thermometer and a mechanical stirring device. At 40°C, adjust the pH to about 10 with ammonia water, continue stirring for 2h, and age for 10h to obtain an aging solution. Filter and wash the obtained aging solution with deionized water until it is neutral. Take the filter cake and dry it in a 100°C oven for 24h to obtain dry particles. Disperse the particles in 300mL of deionized water, add phosphoric acid modifier, stir for 2h, age at room temperature for 12h, dry in a 100°C oven for 24h, and finally calcine at 400°C in a muffle furnace for 4h to obtain CaMoPO x Composite oxide catalysts.

[0075] Example 8: CaWPSO x Preparation of composite oxide catalysts

[0076] Dissolve 38.4g of calcium nitrate tetrahydrate, 52.8g of sodium hydroxide, and 36.5g of phosphotungstic acid in 350mL of deionized water and dissolve them by ultrasonication at 25°C. Transfer the evenly dissolved mixture to a 1000mL three-necked flask equipped with a thermometer and a mechanical stirring device, start stirring, heat in an oil bath until the temperature stabilizes to 40°C, continue stirring for 2h, and age for 36h to obtain an aging solution. Filter the obtained aging solution with deionized water, wash it until it is neutral, take the filter cake and dry it in a 110°C oven for 12h to obtain dry particles. Disperse the particles in 300mL of deionized water, add sulfuric acid modifier, stir for 2h, age at room temperature for 36h, and finally calcine at 600°C in a muffle furnace for 2h to obtain CaWPSO x Composite oxide catalysts.

[0077] Example 9: Supported CaWPSO x Preparation of Mg / SiO2 composite oxide catalyst

[0078] Dissolve 24.6g of calcium nitrate tetrahydrate, 58.9g of sodium hydroxide, and 26.3g of phosphotungstic acid in 450mL of deionized water and dissolve them by ultrasonication at 25°C. Transfer the evenly dissolved mixture to a 1000mL three-necked flask equipped with a thermometer and a mechanical stirring device, add 54.8g of silica, start stirring, heat in an oil bath until the temperature stabilizes to 40°C, continue stirring for 2h, and age for 12h to obtain an aging solution. The obtained aging solution is filtered and washed with deionized water until it is neutral. The filter cake is dried in an oven at 110°C for 12h to obtain dry particles. The particles are dispersed in 300mL of deionized water, sulfuric acid modifier is added, stirred for 2h, aged at room temperature for 36h, and finally calcined at 600°C in a muffle furnace for 2h to obtain loaded CaWPSO. x / SiO2 composite oxide catalyst.

[0079] The catalysts prepared in Examples 1-9 and commercial (commercially available) WO3 and Ca3(PO4)2 (common catalysts in the prior art) were respectively placed in a fixed bed reaction evaluation device for evaluation. The raw materials were 30 wt% caprolactam in acetonitrile and ammonia, with a molar ratio of ammonia to caprolactam of 30:1, the reaction temperature was 300°C, and the space velocity was 3h -1 , atmospheric pressure, the performance results of each catalyst are shown in Table 1.

[0080] Table 1 Comparison of catalytic performance of various catalysts

[0081]

[0082] From the reaction results in Table 1, it can be seen that the catalytic performance of the solid composite oxide catalyst provided by the present invention is significantly better than that of the catalyst of the prior art solution, the conversion rate of the raw material is significantly higher, and the selectivity of the target product is also significantly better.

[0083] The catalyst CaWPSOx prepared in Example 8 is taken as an example, and the reaction conditions and stability are investigated, as shown in Examples 10 to 12.

[0084] Example 10

[0085] The catalyst was evaluated using a fixed bed reaction evaluation device. The raw materials were acetonitrile solution containing 30 wt% caprolactam and ammonia, the reaction temperature was 330 ° C, and the space velocity was 3h -1 The molar ratio of ammonia to caprolactam is 30:1, and the experimental results show that the conversion rate of caprolactam is 99.5% and the selectivity of 6-aminocapronitrile is 99.7%.

[0086] Example 11

[0087] The catalyst was evaluated using a fixed bed reaction evaluation device. The raw materials were acetonitrile solution containing 50 wt% caprolactam and ammonia, the reaction temperature was 300 ° C, and the space velocity was 3h -1 The molar ratio of ammonia to caprolactam is 30:1, and the experimental results at normal pressure show that the conversion rate of caprolactam is 95.2% and the selectivity of 6-aminocapronitrile is 99.5%.

[0088] Example 12

[0089] The catalyst was evaluated using a fixed bed reaction evaluation device. The raw materials were acetonitrile solution containing 30 wt% caprolactam and ammonia, the reaction temperature was 300 ° C, and the space velocity was 15 h -1 The molar ratio of ammonia to caprolactam is 30:1, and the experimental results at normal pressure show that the conversion rate of caprolactam is 96.2% and the selectivity of 6-aminocapronitrile is 99.5%.

[0090] Example 13

[0091] Investigation of the stability of CaWPSOx composite oxide catalyst

[0092] The stability of the catalyst was determined using a fixed bed reaction evaluation device. The raw materials were acetonitrile solution containing 30 wt% caprolactam and ammonia, the reaction temperature was 300 ° C, and the space velocity was 3h -1 The molar ratio of ammonia to caprolactam is 30:1, atmospheric pressure, and the catalyst stability test results are as follows Figure 1 shown.

[0093] Depend on Figure 1 The catalyst stability test results show that the conversion rate of caprolactam and the selectivity of 6-aminocapronitrile remain stable after the catalyst is operated for nearly 300 hours, indicating that the CaWPSOx composite oxide catalyst provided by the present invention has excellent stability.

Claims

1. A method for preparing 6-aminocapronitrile by aminolysis of caprolactam, characterized in that A caprolactam solution is mixed with ammonia gas, and an ammonolysis reaction occurs under the action of a solid composite oxide catalyst to produce a 6-aminocapronitrile product in one step. The solid composite oxide catalyst is composed of a main active component and a co-active component, wherein the main active component is selected from one or more of calcium, aluminum, magnesium, barium, strontium, titanium, zirconium, vanadium, niobium, chromium, molybdenum, tungsten, manganese, iron, zinc, copper, cobalt, nickel, antimony, bismuth, lanthanum, and cerium, and the co-active component is selected from one or more of silicon, sulfur, selenium, boron, nitrogen, fluorine, phosphorus, arsenic, tellurium, and iodine.

2. The method according to claim 1, characterized in that The auxiliary active component accounts for 0.5-50wt%, or 1-45wt%, or 1.5-30wt%, or 2-25wt%, or 2.5-20wt% of the total mass of the composite catalyst. 3 . The method according to claim 1 , wherein the solid composite oxide catalyst is prepared by a sol-gel method, a precipitation method or a hydrothermal method.

4. The method according to claim 1, wherein The solid composite oxide catalyst is a supported catalyst, and the carrier is selected from silica gel, silicon dioxide, alumina, molecular sieves, activated carbon, hydrotalcite or natural minerals; the natural minerals include sepiolite, diatomaceous earth, attapulgite or montmorillonite, and the molecular sieves include ZSM-5, HZSM-5, MCM-41, SBA-15, Y-type molecular sieve or mordenite.

5. The method according to claim 1, wherein The ammonolysis reaction is carried out in a fixed bed, fluidized bed or trickle bed reactor.

6. The method according to claim 1, wherein The solvent of the caprolactam solution is selected from one or more of methanol, ethanol, tert-butanol, acetonitrile, benzene, toluene and dioxane.

7. The method according to claim 1 or 6, characterized in that The mass concentration of the caprolactam solution is 5-80 wt%, or 10-60 wt%, or 20-40 wt%.

8. The method according to claim 1 or 6, characterized in that The molar ratio of ammonia to caprolactam is 2 to 300:1, or 5 to 250:1, or 10 to 200:

1.

9. The method according to claim 1, characterized in that The temperature of the ammonolysis reaction is 100-500°C, or 140-400°C, or 180-350°C.

10. The method according to claim 1, characterized in that The aminolysis reaction pressure is ≤6 MPa, preferably ≤4 MPa, more preferably ≤2 MPa.

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