Catalyst for synthesizing aminocapronitrile from caprolactam as well as preparation method and application of catalyst

Abstract

The invention provides a catalyst for synthesizing aminocapronitrile from caprolactam as well as a preparation method and application of the catalyst. The preparation method comprises the following steps: (1) carrying out alkali treatment and ammonium exchange on a molecular sieve carrier, and calcining to obtain a pretreated carrier; (2) placing the pretreated carrier in a metal salt solution for ion exchange to obtain a first catalyst precursor; (3) carrying out phosphoric acid treatment on the first catalyst precursor to obtain a second catalyst precursor; (4) putting the second catalyst precursor into a treating fluid containing a silicon source and an aluminum source, and carrying out hydrothermal treatment to obtain a third catalyst precursor; and (5) carrying out acid treatment on the third catalyst precursor to obtain the catalyst for synthesizing aminocapronitrile from caprolactam. The preparation method is simple to operate and easy to amplify, and the prepared catalyst is high in catalytic activity and long in service life and can be widely applied to a production process for synthesizing aminocapronitrile from caprolactam industrially.

Description

Technical Field

[0001] The invention relates to the technical field of chemical synthesis, and in particular to a catalyst for synthesizing aminocapronitrile from caprolactam, and a preparation method and application thereof. Background Art

[0002] 1,6-Hexanediamine (hereinafter referred to as hexanediamine) is one of the three major raw materials for nylon production. As an important chemical intermediate, it can react with adipic acid and sebacic acid to produce nylon 66 and nylon 610 products, and then make various nylon resins, nylon fibers and engineering plastic products. It can also be used to synthesize diisocyanates, epoxy resins or urea-formaldehyde resin curing agents, organic crosslinking agents, etc. As the global demand for nylon products continues to expand, nylon companies are required to continuously expand their production capacity.

[0003] There are many methods for industrial production of hexamethylenediamine, such as butadiene hydrocyanation, acrylonitrile electrolysis, and adipic acid ammoniation dehydration. However, almost all large-scale production methods of hexamethylenediamine start with adiponitrile. Due to the extremely high technical barriers of adiponitrile, the supply of adiponitrile and hexamethylenediamine has always been at a high cost, which is not conducive to the expansion of the production scale of hexamethylenediamine. In contrast, the raw material caprolactam of the caprolactam ammoniation dehydration method has a wide source, simple reaction conditions, low equipment investment, and non-corrosive raw materials, which is suitable for industrial production.

[0004] The process for preparing hexamethylenediamine by caprolactam ammoniation and dehydration comprises the following steps: 1) caprolactam undergoes a ring-opening ammoniation and dehydration reaction with ammonia at high temperature to generate 6-aminocapronitrile (hereinafter referred to as aminocapronitrile); 2) aminocapronitrile is hydrogenated to generate 1,6-hexamethylenediamine. The specific reaction formula is as follows:

[0005]

[0006] Compared with the butadiene hydrocyanation method and the adipic acid ammoniation dehydration method, the caprolactam method has the advantages of short process, low raw material toxicity, low equipment cost and high product yield. Especially in recent years, with the continuous expansion of caprolactam production capacity, the process of preparing 6-aminocapronitrile and then producing hexamethylenediamine using caprolactam as raw material has received widespread attention.

[0007] It should be noted that the process of preparing aminocapronitrile by ammoniation of caprolactam is carried out at a high temperature of about 350°C, and caprolactam itself is a heat-sensitive substance, which is prone to coking and depositing on specific acidic sites on the catalyst surface at high temperatures. In addition, the strong alkaline ammonia gas corrodes the catalyst during the amination reaction, which ultimately leads to catalyst coking and deactivation, reduced service life, decreased reaction selectivity, and decreased raw material conversion rate. These conditions will restrict the improvement of production efficiency and capacity in large-scale industrial production. Summary of the invention

[0008] In view of the deficiencies in the prior art, the present invention discloses a catalyst for synthesizing aminocapronitrile from caprolactam, a preparation method and an application thereof. The catalyst preparation method of the present invention has mild conditions, simple operation and is easy to scale up; the prepared catalyst has good catalytic activity and long service life, and is suitable for industrial production of synthesizing aminocapronitrile using caprolactam as a raw material.

[0009] In order to achieve the above technical objectives, on the one hand, the present invention provides a method for preparing a catalyst for synthesizing aminocapronitrile from caprolactam, the method comprising the following steps:

[0010] (1) treating the molecular sieve carrier with alkali and exchanging ammonium, and calcining the carrier to obtain a pretreated carrier;

[0011] (2) placing the pretreated support in a metal salt solution for ion exchange to obtain a first catalyst precursor;

[0012] (3) treating the first catalyst precursor with phosphoric acid to obtain a second catalyst precursor;

[0013] (4) placing the second catalyst precursor in a treatment solution containing a silicon source and an aluminum source, and subjecting the treatment to hydrothermal treatment to obtain a third catalyst precursor;

[0014] (5) The third catalyst precursor is acid-washed to obtain the catalyst for synthesizing aminocapronitrile from caprolactam.

[0015] In step (1) of the above technical solution, the molecular sieve carrier is treated with alkali to make the molecular sieve framework structure have defects and pores where ion exchange can occur, and through ammonium exchange and calcination operations, the ion exchangeable positions in the molecular sieve are changed into H atoms; in step (2), H atoms are exchanged with metal salt ions, so that metal cations are dispersed into the molecular sieve framework by atomic-level replacement; after step (3) phosphoric acid treatment, a uniformly distributed metal phosphate active phase is formed in the molecular sieve framework, which is not only conducive to improving the stability of the catalyst structure and thus increasing the service life of the catalyst, but also avoiding the agglomeration of active components and improving the catalyst performance of the catalyst. Further, in step (4) of the above technical solution, the second catalyst precursor is subjected to hydrothermal treatment containing silicon and aluminum sources to form an aluminum-rich layer on the surface of the molecular sieve; step (5) removes free aluminum that has not entered the molecular sieve framework structure by pickling to obtain the catalyst product; the aluminum-rich layer in the catalyst product can repair the framework structure of the molecular sieve, enhance alkali resistance and adjust the electron density on the surface of the molecular sieve, effectively prevent the occurrence of catalyst coking, and further increase the service life of the catalyst.

[0016] Based on the above technical scheme, the present invention does not limit the type of the molecular sieve carrier, and those skilled in the art can select a suitable molecular sieve to prepare a catalyst for the synthesis of aminocapronitrile from caprolactam according to actual working conditions. In an optional example of the present invention, the molecular sieve carrier includes at least one of S-1 molecular sieve, ZSM-5 molecular sieve, β molecular sieve, Y molecular sieve, mordenite molecular sieve, SAPO molecular sieve, and MCM molecular sieve.

[0017] Based on the above technical solution, the alkali treatment is used to create pores in the molecular sieve carrier, increase the specific surface area of ​​the carrier, and at the same time make the molecular sieve framework structure have defects and vacancies that can cause ion exchange. Optionally, the alkali treatment in step (1) includes: contacting the molecular sieve carrier with an alkaline solution.

[0018] The present invention does not limit the type of alkali used for alkali treatment, and any alkali that can remove silicon from the molecular sieve structure and facilitate pore formation is sufficient. In an optional example of the present invention, the alkali used for alkali treatment includes one of lithium hydroxide, sodium hydroxide, potassium hydroxide, and barium hydroxide.

[0019] The present invention does not limit the type of solvent of the alkaline solution, and any solvent that can be used to prepare the alkaline solution by mixing the alkali solution. In a further optional example of the present invention, the solvent of the alkaline solution includes one of water, methanol, ethanol, isopropanol, and tert-butanol.

[0020] In a further optional example of the present invention, the mass concentration of the alkaline solution is 2-50%.

[0021] In a further optional example of the present invention, the temperature of the alkali treatment is 30 to 120° C., and the treatment time is 2 to 10 hours, which is beneficial to improving the pore-forming efficiency.

[0022] The present invention does not limit the amount of alkaline solution, as long as the molecular sieve carrier can be fully in contact with the alkaline solution. It can be understood that in the actual process, the molecular sieve carrier is immersed in the alkaline solution as a whole; in an optional example of the present invention, the alkaline solution can be recycled.

[0023] The present invention does not limit the number of alkali treatments. It is understood that, depending on the amount and concentration of the alkali solution, in the actual process, the molecular sieve carrier can be treated once with a large amount of relatively high-concentration alkali solution, or the molecular sieve carrier can be treated multiple times with a relatively low-concentration alkali solution to achieve the purpose of pore formation and obtaining ion-exchangeable sites. In a further optional example of the present invention, the number of alkali treatments is 1 to 5 times.

[0024] In a further optional example of the present invention, the carrier is washed and dried after the alkali treatment to improve the operability of subsequent processes.

[0025] Based on the above technical solution, alkali metal or alkaline earth metal may be introduced into the molecular sieve framework during the alkali treatment process, and the introduced alkali metal or alkaline earth metal is replaced with ammonium radicals through the ammonium exchange process, and the ion exchangeable position is converted into H atom through calcination operation to facilitate subsequent metal cation ion exchange. In an optional example of the present invention, the ammonium exchange includes: contacting the alkali-treated carrier with an ammonium nitrate solution.

[0026] In a further optional example of the present invention, the mass concentration of the ammonium nitrate solution is 1-10%.

[0027] In a further optional example of the present invention, the temperature of the ammonium exchange is 30 to 120° C., and the processing time is 6 to 24 hours, thereby improving the efficiency of the ammonium exchange.

[0028] The present invention does not limit the number of ammonium exchanges. In a further optional example of the present invention, the number of ammonium exchanges is 1 to 5 times. In the actual process, the appropriate number of ammonium exchanges can be selected as needed.

[0029] The present invention does not limit the control conditions of the carrier calcination operation after ammonium exchange. Those skilled in the art can select appropriate calcination conditions to convert the ammonium radicals at the ion-exchangeable positions into H atoms through very creative labor. For example, calcination can be performed at a temperature of 400 to 800° C. for 4 to 12 hours. The technical solutions thus formed are all within the protection scope of the present invention.

[0030] The present invention does not limit the amount of ammonium salt aqueous solution used, as long as the carrier treated with alkali can be in contact with the ammonium salt solution to fully exchange ammonium ions. It can be understood that in the actual process, the molecular sieve carrier is immersed in the ammonium salt solution as a whole; in an optional example of the present invention, the ammonium salt solution can be recycled.

[0031] Based on the above technical solution, in step (2), the pretreated carrier is placed in a metal salt solution to exchange cations in the metal salt solution with H atoms in the ion-exchangeable positions in the carrier, thereby uniformly dispersing the metal cations into the framework of the molecular sieve. In an optional example of the present invention, the metal salt solution in step (2) is prepared by dissolving a metal salt in water.

[0032] In a further optional example of the present invention, the cation of the metal salt may optionally include Ni 2+ 、Co 2+ 、Ce 3+ , Fe 3 + Mg 2+ ,La + , Mn 4+ 、Zn 2+ At least one of .

[0033] The present invention does not limit the type of anion of the metal salt, and any anion type that can make the metal salt soluble in water is sufficient. In a further optional example of the present invention, the anion of the metal salt includes at least one of nitrate, formate, acetate, and benzoate, and those skilled in the art can select a suitable soluble metal salt for preparing the metal salt solution according to specific working conditions.

[0034] In a further optional example of the present invention, the mass concentration of the metal salt solution is 1-20%.

[0035] In a further optional example of the present invention, the temperature of the ion exchange is 30 to 120° C., and the treatment time is 2 to 10 hours.

[0036] The present invention does not limit the number of ion exchanges in the ammonium step (2). In a further optional example of the present invention, the number of ion exchanges in step (2) is 1 to 5 times. In the actual process, the appropriate number of ion exchanges can be selected as needed.

[0037] In a further optional example of the present invention, the step (2) further includes washing and calcining the catalyst precursor after ion exchange, washing with water to neutrality to remove metal residues on the surface of the first catalyst precursor, and then calcining to improve the stability of the structure of the first catalyst precursor. Further optionally, the temperature of the calcination operation is 400 to 800°C, and the calcination time is 4 to 12 hours. Further optionally, between the washing operation and the calcination operation, an operation of drying the first catalyst precursor is also included to improve the calcination operability and calcination efficiency.

[0038] Based on the above technical solution, phosphoric acid treatment can make the metal cations dispersed in the molecular sieve framework in the first catalyst precursor adsorb phosphate, forming a stable metal phosphate active component in the framework during analysis. In an optional example of the present invention, the phosphoric acid treatment in step (3) includes: contacting the first catalyst precursor with a phosphoric acid solution.

[0039] In a further optional example of the present invention, the mass concentration of the phosphoric acid solution is 5-20%.

[0040] In a further optional example of the present invention, the temperature of the phosphoric acid treatment is 30 to 100° C., and the treatment time is 8 to 24 hours.

[0041] The present invention does not limit the amount of phosphoric acid solution used, as long as the first catalyst precursor can be fully in contact with the phosphoric acid solution. It can be understood that in the actual process, the first catalyst precursor is immersed in the phosphoric acid solution as a whole; in an optional example of the present invention, the phosphoric acid solution can be recycled.

[0042] In a further optional example of the present invention, step (3) further includes taking out the second catalyst precursor that has completed the phosphoric acid treatment, washing it to neutrality, and drying it to enhance the stability of the metal phosphate active component.

[0043] Based on the above technical scheme, in the step (3), the second catalyst precursor is hydrothermally treated in a treatment solution containing a silicon source and an aluminum source, and aluminum atoms are embedded in the conformation formed on the surface of the molecular sieve to form an aluminum-rich layer. The formation of the aluminum-rich layer can enhance the alkali resistance of the catalyst itself; in addition, the formation of the aluminum-rich layer destroys the acidic sites on the surface of the analytical sieve that are prone to caprolactam coking deposition, thereby reducing the adhesion of coking on the catalyst surface and increasing the service life of the catalyst.

[0044] The present invention does not limit the source of the silicon source. In an optional example of the present invention, the silicon source in step (4) includes at least one of 30% silica sol, tetraethyl orthosilicate, gas phase silicon oxide, silicic acid, and metasilicic acid. Those skilled in the art can select a suitable silicon source according to their needs.

[0045] The present invention does not limit the source of the aluminum source. In an optional example of the present invention, the aluminum source in step (4) includes at least one of 20% aluminum sol, pseudo-boehmite, sodium aluminate, and γ-alumina. Those skilled in the art can select a suitable silicon source as needed.

[0046] In an optional example of the present invention, the atomic ratio of silicon to aluminum in the treatment solution is 10 to 100, and a suitable ratio of silicon atoms to aluminum atoms is conducive to embedding aluminum atoms into the conformation of the molecular sieve surface during hydrothermal treatment.

[0047] In an optional example of the present invention, the mass ratio of the sum of the mass of the silicon source and the aluminum source in the treatment liquid to the mass of the second catalyst precursor is (0.2-1):1.

[0048] The present invention does not limit the specific operation of the hydrothermal treatment. In an optional example of the present invention, the temperature of the hydrothermal treatment is 120-200°C, and the hydrothermal treatment time is 2-12 hours, which provides suitable control conditions for the formation of an aluminum-rich layer on the surface of the molecular sieve.

[0049] In an optional example of the present invention, the step (4) further comprises taking out the third catalyst precursor, washing it to neutrality, and drying it.

[0050] Based on the above technical solution, the third catalyst precursor is acid-washed to remove free aluminum not embedded in the molecular sieve framework, further improving the service life of the catalyst. In an optional example of the present invention, the acid washing in step (5) includes: contacting the third catalyst precursor with an acid.

[0051] The present invention does not limit the type of acid used for pickling, and can be used to wash and remove the aluminum atoms remaining on the surface of the molecular sieve. In a further optional example of the present invention, the acid in step (5) includes at least one of nitric acid, sulfuric acid, hydrochloric acid, oxalic acid, and citric acid, and technicians in the art can select a suitable type of acid for treating the third catalyst precursor as needed.

[0052] In a further optional example of the present invention, the mass concentration of the acid in step (5) is 10-50%.

[0053] In a further optional example of the present invention, the pickling temperature in step (5) is 30 to 100° C., and the treatment time is 2 to 12 hours.

[0054] In a further optional example of the present invention, the step (5) further includes washing and calcining the catalyst precursor after acid washing. The organic impurities in the catalyst can be removed by calcining with a detergent, thereby improving the catalytic performance of the catalyst. Further optionally, the calcination temperature is 400 to 800°C, and the calcination time is 4 to 12 hours; further optionally, between the washing operation and the calcination operation, an operation of drying the first catalyst precursor is also included, thereby improving the calcination operability and calcination efficiency.

[0055] The present invention does not limit the amount of acid solution used, as long as the third catalyst precursor is fully in contact with the acid solution. It is understandable that in the actual process, the third catalyst precursor is immersed in the acid as a whole; in an optional example of the present invention, the acid can be recycled.

[0056] On the other hand, the present invention provides a catalyst for synthesizing aminocapronitrile from caprolactam, which is prepared by the above preparation method.

[0057] On the other hand, the present invention proposes the use of the catalyst for synthesizing aminocapronitrile from caprolactam in preparing aminocapronitrile by amination using caprolactam as a raw material.

[0058] Compared with the prior art, the beneficial effects of the present invention are as follows: the catalyst preparation method of the present invention makes the metal phosphate active component uniformly and stably dispersed in the framework structure of the molecular sieve through ion exchange and phosphoric acid treatment, thereby improving the catalytic activity and product selectivity of the catalyst; further, by forming an aluminum-rich layer on the surface of the molecular sieve, the service life of the catalyst is significantly improved. The preparation method of the present invention is simple to operate and easy to scale up. The prepared catalyst for synthesizing aminocapronitrile from caprolactam has high catalytic activity and long service life, and can be widely used in the industrialized production process of synthesizing aminocapronitrile from caprolactam; the catalyst cost and process maintenance cost of the aminocapronitrile method using the catalyst of the present invention are reduced, and the labor cost is reduced, which brings significant economic benefits to the large-scale production of aminocapronitrile. BRIEF DESCRIPTION OF THE DRAWINGS

[0059] The drawings constituting a part of the present application are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0060] Figure 1 The electron microscope morphology of the catalyst prepared in Example 6 of the present invention is shown. DETAILED DESCRIPTION

[0061] In order to facilitate the understanding of the present invention, the present invention will be described more comprehensively below, and preferred embodiments of the present invention are given. However, it should be understood that these embodiments are only used for more detailed description and should not be understood as limiting the present invention in any form, i.e., not intended to limit the scope of protection of the present invention.

[0062] Unless otherwise defined, the technical terms used in the following examples have the same meanings as those generally understood by those skilled in the art to which the present invention belongs. The test reagents used in the following examples, unless otherwise specified, are all conventional biochemical reagents; the experimental methods, unless otherwise specified, are all conventional methods.

[0063] The terms "first", "second", "third", etc. are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Therefore, a feature defined as "first", "second", "third", etc. may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "plurality" means two or more.

[0064] The service life of the catalyst of the present invention is detected by a long-time evaluation method. When the conversion rate of the reaction is lower than 80% of the initial conversion rate, the catalyst is considered to be deactivated.

[0065] The catalyst evaluation method is as follows: using ammonia and caprolactam as raw materials, the catalyst is used to prepare aminocapronitrile in a fixed bed reactor, the reaction temperature is 280-400°C, and the caprolactam reaction space velocity is 0.2-4.0h -1 ; Among them, the single-pass conversion rate of caprolactam = (1-the percentage of caprolactam content in the reaction solution) × 100%, the yield of aminocapronitrile = the percentage of aminocapronitrile content in the reaction solution / (1-the content of caprolactam in the reaction solution) × 100%.

[0066] Example 1

[0067] A method for preparing a catalyst for synthesizing aminocapronitrile from caprolactam, specifically:

[0068] (1) Prepare a 10% NaOH solution and heat it to 30° C. Place the β molecular sieve carrier in the alkaline solution for treatment for 10 hours. After the treatment, wash the carrier to neutrality and dry it. Repeat the alkaline treatment for a total of 5 times.

[0069] Prepare 10% ammonium nitrate solution and heat it to 30°C. Place the alkali-treated carrier in the ammonium nitrate solution for 6 hours. After the treatment, wash the carrier to neutrality and dry it. Repeat the ammonium nitrate treatment for 5 times. Calcine the carrier at 600°C for 10 hours to obtain the pretreated carrier.

[0070] (2) Prepare a mixed salt solution of zinc acetate and magnesium acetate with a mass concentration of 5% (the ratio of zinc to magnesium in atoms is 1:2), and heat it to 30°C. Place the pretreated carrier in the metal salt solution for ion exchange treatment for 10 hours. After the treatment, wash the carrier to neutrality and dry it. Repeat the metal salt ion exchange treatment for a total of 5 times. Calcine the catalyst precursor after ion exchange at 600°C for 10 hours. Obtain the first catalyst precursor.

[0071] (3) Prepare a phosphoric acid solution with a concentration of 20%, heat it to 30° C., place the first catalyst precursor in the phosphoric acid solution for treatment for 24 hours, and after the treatment, wash the catalyst precursor to neutrality and dry it to obtain a second catalyst precursor.

[0072] (4) Dissolve 30% silica sol in water, stir evenly, then add pseudo-boehmite, the atomic ratio of silicon to aluminum is 25, stir the liquid until it forms a uniform treatment liquid, the total mass of the silicon source and the aluminum source is 1 kg; place 1 kg of the second catalyst precursor in the treatment liquid, mix evenly, heat to 200° C. in a hydrothermal kettle, and perform hydrothermal treatment for 2 hours. After the treatment is completed, neutralize the catalyst precursor and dry it. A third catalyst precursor is obtained.

[0073] (5) Prepare a 20% hydrochloric acid solution and heat it to 30° C. Place the third catalyst precursor in the hydrochloric acid solution for 12 hours. After the treatment, wash the catalyst to neutrality and dry it. Calcining the catalyst at 800° C. for 6 hours. A catalyst for synthesizing aminocapronitrile from caprolactam is obtained.

[0074] Example 2

[0075] A method for preparing a catalyst for synthesizing aminocapronitrile from caprolactam, specifically:

[0076] (1) Prepare a 2% Ca(OH)2 solution and heat it to 120°C. Place the Y molecular sieve carrier in the Ca(OH)2 solution for 2 hours. After the treatment, wash the molecular sieve to neutrality and dry it.

[0077] Prepare 1% ammonium nitrate solution and heat it to 120°C. Place the alkali-treated carrier in the ammonium nitrate solution for 24 hours. After the treatment, wash the carrier to neutrality and dry it. Calcining the catalyst at 600°C for 10 hours. Obtain the pretreated carrier.

[0078] (2) Prepare a metal salt solution of nickel citrate and cobalt citrate with a mass concentration of 1% (the ratio of nickel to cobalt in atoms is 1:1), and heat it to 120° C. Place the pretreated carrier in the metal salt solution for ion exchange treatment for 24 hours. After the treatment, wash the carrier to neutrality and dry it. Calcining the catalyst precursor after ion exchange at 800° C. for 4 hours to obtain a first catalyst precursor.

[0079] (3) Prepare a 5% phosphoric acid solution and heat it to 100° C. Place the first catalyst precursor in the phosphoric acid solution for treatment for 8 hours. After the treatment, wash the catalyst precursor to neutrality and dry it to obtain a second catalyst precursor.

[0080] (4) Dissolve fumed silicon oxide in water, stir evenly, then add 20% aluminum sol, the atomic ratio of silicon to aluminum is 10, stir the liquid until it forms a uniform treatment liquid, the total mass of silicon source and aluminum source is 0.5 kg; place 1 kg of the second catalyst precursor in the treatment liquid, mix evenly, heat to 120° C. in a hydrothermal autoclave, hydrothermally treat for 12 hours, wash the catalyst precursor to neutrality after the treatment is completed, and dry it to obtain a third catalyst precursor.

[0081] (5) Prepare a 10% oxalic acid solution and heat it to 80° C. Place the third catalyst precursor in the oxalic acid solution for 6 hours. After the treatment, wash the catalyst to neutrality and dry it. Calcining the catalyst at 500° C. for 6 hours. A catalyst for synthesizing aminocapronitrile from caprolactam is obtained.

[0082] Example 3

[0083] A method for preparing a catalyst for synthesizing aminocapronitrile from caprolactam, specifically:

[0084] (1) Prepare a 50% KOH ethanol solution and heat it to 50°C. Place the ZSM-5 molecular sieve carrier in the KOH ethanol solution for 10 hours. After the treatment, wash the molecular sieve to neutrality and dry it. Repeat the alkaline treatment for a total of 5 times.

[0085] Prepare 10% ammonium nitrate solution and heat it to 80°C. Place the alkali-treated carrier in the ammonium nitrate solution for 24 hours. After the treatment, wash the carrier to neutrality and dry it. Repeat the ammonium nitrate treatment for 2 times. Calcine the carrier at 600°C for 10 hours to obtain the pretreated carrier.

[0086] (2) Prepare a 5% metal salt solution of zinc acetate and magnesium acetate (the ratio of zinc to magnesium in atoms is 1:2), and heat it to 30°C. Place the pretreated carrier in the metal salt solution for ion exchange treatment for 10 hours. After the treatment, wash the carrier to neutrality and dry it. Repeat the metal salt treatment for a total of 3 times. Calcine the catalyst precursor after ion exchange at 400°C for 24 hours. Obtain the first catalyst precursor.

[0087] (3) Prepare a 10% phosphoric acid solution and heat it to 80° C. Place the first catalyst precursor in the phosphoric acid solution for treatment for 24 hours. After the treatment, wash the molecular sieve to neutrality and dry it. Repeat the phosphoric acid treatment for a total of 3 times to obtain a second catalyst precursor.

[0088] (4) Tetraethyl orthosilicate was dissolved in water, stirred evenly, and then pseudo-boehmite was added thereto, with the atomic ratio of silicon to aluminum being 10, and the liquid was stirred until a uniform treatment liquid was formed, with the total mass of the silicon source and the aluminum source being 0.2 kg; 1 kg of the second catalyst precursor was placed in the treatment liquid, mixed evenly, and heated to 180° C. in a reactor for hydrothermal treatment for 8 h. After the treatment was completed, the catalyst precursor was washed to neutrality and dried. A third catalyst precursor was obtained.

[0089] (5) Prepare a nitric acid solution with a concentration of 50%, heat it to 80°C, place the catalyst in the nitric acid solution for treatment for 8 hours, wash the catalyst to neutrality after treatment, and dry it. Calcining the catalyst at 600°C for 4 hours, obtain a catalyst for synthesizing aminocapronitrile from caprolactam.

[0090] Example 4

[0091] A method for preparing a catalyst for synthesizing aminocapronitrile from caprolactam, specifically:

[0092] (1) Prepare a 10% Ba(OH)2 isopropanol solution and heat it to 90°C. Place the S-1 molecular sieve carrier in the Ba(OH)2 isopropanol solution for 10 hours. After the treatment, wash the molecular sieve to neutrality and dry it. Repeat the alkaline treatment for a total of 2 times.

[0093] Prepare 2% ammonium nitrate solution and heat it to 90°C. Place the alkali-treated carrier in the ammonium nitrate solution for 18 hours. After the treatment, wash the carrier to neutrality and dry it. Repeat the ammonium nitrate treatment for 3 times. Calcine the catalyst at 600°C for 10 hours. Obtain the pretreated carrier.

[0094] (2) Prepare a 12% metal salt solution of iron nitrate and manganese nitrate (iron and manganese in an atomic ratio of 3:1), heat it to 80°C, place the pretreated carrier in the metal salt solution for ion exchange treatment for 6 hours, and after the treatment, wash the carrier to neutrality and dry it. Repeat the metal salt treatment for a total of 3 times. Calcine the catalyst precursor after ion exchange at 550°C for 11 hours. Obtain the first catalyst precursor.

[0095] (3) Prepare a phosphoric acid solution with a concentration of 15%, heat it to 90° C., place the first catalyst precursor in the phosphoric acid solution for treatment for 16 hours, wash the catalyst precursor to neutrality after the treatment, and dry it, repeat the phosphoric acid treatment for a total of 4 times to obtain a second catalyst precursor.

[0096] (4) Dissolve metasilicic acid in water, stir evenly, then add sodium aluminate, the atomic ratio of silicon to aluminum is 100, stir the liquid until it forms a uniform treatment liquid, the total mass of the silicon source and the aluminum source is 0.25 kg; place 1 kg of the second catalyst precursor in the treatment liquid, mix evenly, heat to 200° C. in a reactor, and perform hydrothermal treatment for 3 hours. After the treatment is completed, wash the catalyst precursor to neutrality and dry it. A third catalyst precursor is obtained.

[0097] (5) Prepare a 50% citric acid solution and heat it to 90°C. Place the catalyst in the citric acid solution for treatment for 8 hours. After the treatment, wash the catalyst to neutrality and dry it. Calcining the catalyst at 700°C for 10 hours. A catalyst for synthesizing aminocapronitrile from caprolactam is obtained.

[0098] Example 5

[0099] A method for preparing a catalyst for synthesizing aminocapronitrile from caprolactam, specifically:

[0100] (1) Prepare a 2% LiOH tert-butanol solution and heat it to 50°C. Place the MCM molecular sieve carrier in the LiOH tert-butanol solution for 10 hours. After the treatment, wash the carrier to neutrality and dry it. Repeat the alkaline treatment for a total of 5 times.

[0101] Prepare 10% ammonium nitrate solution and heat it to 50°C. Place the alkali-treated carrier in the ammonium nitrate solution for 24 hours. After the treatment, wash the molecular sieve to neutrality and dry it. Repeat the ammonium nitrate treatment for 3 times. Calcine the catalyst at 500°C for 6 hours. Obtain the pretreated carrier.

[0102] (2) Prepare a 5% cerium formate solution and heat it to 80°C. Place the pretreated carrier in the cerium formate metal salt solution for ion exchange treatment for 3 hours. After the treatment, wash the carrier to neutrality and dry it. Repeat the metal salt treatment for a total of 5 times. Calcine the catalyst at 450°C for 12 hours to obtain the first catalyst precursor.

[0103] (3) Prepare a 10% phosphoric acid solution and heat it to 50° C. Place the first catalyst precursor in the phosphoric acid solution for treatment for 12 hours. After the treatment, wash the catalyst precursor to neutrality and dry it. Repeat the phosphoric acid treatment for a total of 5 times to obtain a second catalyst precursor.

[0104] (4) Dissolve fumed silicon oxide in water, stir evenly, then add γ-alumina, the atomic ratio of silicon to aluminum is 80, stir the liquid until it forms a uniform treatment liquid, the total mass of silicon source and aluminum source is 0.7 kg; place 1 kg of the second catalyst precursor in the treatment liquid, mix evenly, heat to 200° C. in a hydrothermal autoclave, and perform hydrothermal treatment for 10 hours. After the treatment is completed, wash the catalyst precursor to neutrality and dry it. A third catalyst precursor is obtained.

[0105] (5) Prepare a sulfuric acid solution with a concentration of 35%, heat it to 50°C, place the catalyst in the sulfuric acid solution for treatment for 2 hours, wash the catalyst to neutrality after treatment, and dry it. Calcining the catalyst at 450°C for 12 hours, obtain a catalyst for the synthesis of aminocapronitrile from caprolactam.

[0106] Example 6

[0107] A method for preparing a catalyst for synthesizing aminocapronitrile from caprolactam, specifically:

[0108] (1) Prepare a 50% NaOH ethanol solution and heat it to 40° C. Place the mordenite molecular sieve carrier in the NaOH ethanol solution for treatment for 2 hours. After the treatment, wash the carrier to neutrality and dry it.

[0109] Prepare 3% ammonium nitrate solution and heat it to 80°C. Place the alkali-treated carrier in the ammonium nitrate solution for 6 hours. After the treatment, wash the carrier to neutrality and dry it. Repeat the ammonium nitrate treatment for 5 times. Calcine the catalyst at 750°C for 6 hours. Obtain the pretreated carrier.

[0110] (2) Prepare a 20% lanthanum nitrate solution and heat it to 40°C. Place the pretreated carrier in the lanthanum nitrate solution for ion exchange treatment for 10 hours. After the treatment, wash the carrier to neutrality and dry it. Repeat the metal salt treatment for a total of 3 times. Calcine the catalyst precursor at 500°C for 8 hours. Obtain the first catalyst precursor.

[0111] (3) Prepare a phosphoric acid solution with a concentration of 20%, heat it to 40° C., place the first catalyst precursor in the phosphoric acid solution for treatment for 6 hours, wash the catalyst precursor to neutrality after the treatment, and dry it, repeat the phosphoric acid treatment for a total of 4 times to obtain a second catalyst precursor.

[0112] (4) Dissolve silicic acid in water, stir evenly, then add sodium aluminate, the atomic ratio of silicon to aluminum is 50, stir the liquid until it forms a uniform treatment liquid, the total mass of the silicon source and the aluminum source is 0.5 kg; place 1 kg of the second catalyst precursor in the treatment liquid, mix evenly, heat to 120° C. in a reactor, and perform hydrothermal treatment for 3 hours. After the treatment is completed, wash the catalyst precursor to neutrality and dry it. A third catalyst precursor is obtained.

[0113] (5) Prepare 25% oxalic acid solution and heat it to 40°C. Place the catalyst in the oxalic acid solution for 12 hours. After the treatment, wash the catalyst to neutrality and dry it. Calcining the catalyst at 550°C for 12 hours. Obtain a catalyst for preparing aminocapronitrile from caprolactam. Obtain a catalyst for synthesizing aminocapronitrile from caprolactam. The electron microscope morphology of the catalyst is shown in the following figure. Figure 1 .

[0114] Comparative Example 1

[0115] A method for preparing a catalyst comprises the following steps:

[0116] (1) Prepare a metal salt solution of zinc acetate and magnesium acetate with a concentration of 5%, heat it to 30°C, place the β molecular sieve carrier in the metal salt solution for ion exchange treatment for 10 hours, and after the treatment, wash the catalyst precursor to neutrality and dry it. Repeat the metal salt treatment for a total of 5 times. Calcine the catalyst precursor at 600°C for 10 hours.

[0117] (2) Prepare a phosphoric acid solution with a concentration of 20% and heat it to 30° C. Place the catalyst precursor obtained in step (1) in the phosphoric acid solution for treatment for 24 hours. After the treatment, wash the molecular sieve to neutrality and dry it.

[0118] (3) Dissolve 30% silica sol in water, stir evenly, then add pseudo-boehmite, where the atomic ratio of silicon to aluminum is 25, and stir the liquid until it forms a uniform treatment liquid. The total mass of the silicon source and the aluminum source is 1 kg. Place 1 kg of the catalyst precursor obtained in step (2) in the treatment liquid, mix evenly, and place in a hydrothermal autoclave, heat the autoclave to 200°C, and perform hydrothermal treatment for 2 hours. After the treatment is completed, wash the catalyst precursor to neutrality and dry it.

[0119] (4) Prepare a 20% hydrochloric acid solution and heat it to 30°C. Place the catalyst precursor obtained in step (3) in the hydrochloric acid solution for treatment for 12 hours. After the treatment, wash the catalyst to neutrality and dry it. Calcining the catalyst at 800°C for 6 hours to obtain a finished catalyst.

[0120] Comparative Example 2

[0121] A method for preparing a catalyst comprises the following steps:

[0122] (1) Prepare a 2% Ca(OH)2 solution and heat it to 120°C. Place the Y molecular sieve carrier in the Ca(OH)2 solution for 2 hours. After the treatment, wash the carrier to neutrality and dry it.

[0123] Prepare 1% ammonium nitrate solution and heat it to 120°C, place the alkali-treated carrier in the ammonium nitrate solution for 24 hours, wash the carrier to neutrality and dry it, and calcine the carrier at 600°C for 10 hours.

[0124] (2) Prepare a 1% nickel citrate and cobalt citrate metal salt solution (the ratio of nickel to cobalt in atoms is 1:1), and heat it to 120° C. Place the carrier treated in step (1) in the metal salt solution for ion exchange treatment for 24 hours. After the treatment, wash the catalyst precursor to neutrality and dry it. Calcine the catalyst precursor at 800° C. for 4 hours.

[0125] (3) Dissolve fumed silicon oxide in water, stir evenly, then add 20% aluminum sol, where the atomic ratio of silicon to aluminum is 10, and stir the liquid until it forms a uniform treatment liquid. The total mass of the silicon source and the aluminum source is 0.5 kg. Place 1 kg of the catalyst precursor obtained in step (2) in the treatment liquid, mix evenly, heat to 120°C in a hydrothermal autoclave, and perform hydrothermal treatment for 12 hours. After the treatment is completed, wash the catalyst precursor to neutrality and dry it.

[0126] (4) Prepare a 10% oxalic acid solution and heat it to 80° C. Place the catalyst precursor obtained in step (3) in the oxalic acid solution for treatment for 6 hours. After the treatment, wash the catalyst to neutrality and dry it. Calcining the catalyst at 500° C. for 6 hours to obtain a finished catalyst.

[0127] Comparative Example 3

[0128] A method for preparing a catalyst comprises the following steps:

[0129] (1) Prepare a 50% KOH ethanol solution and heat it to 50°C. Place the ZSM-5 molecular sieve carrier in the KOH ethanol solution for 10 hours. After the treatment, wash the carrier to neutrality and dry it. Repeat the alkali treatment for a total of 5 times.

[0130] Prepare 10% ammonium nitrate solution and heat it to 80°C. Place the alkali-treated carrier in the ammonium nitrate solution for 24 hours. After the treatment, wash the carrier to neutrality and dry it. Repeat the ammonium nitrate treatment for 2 times. Calcine the carrier at 600°C for 10 hours.

[0131] (2) Prepare a 5% mixed salt solution of zinc acetate and magnesium acetate (the ratio of zinc to magnesium in atoms is 1:2), and heat it to 30°C. Place the carrier treated in step (1) in the metal salt solution for ion exchange treatment for 10 hours. After the treatment, wash the catalyst precursor to neutrality and dry it. Repeat the metal salt treatment for a total of 3 times. Calcine the catalyst at 400°C for 24 hours.

[0132] (3) Prepare a 10% phosphoric acid solution and heat it to 80°C. Place the catalyst precursor obtained in step (2) in the phosphoric acid solution for treatment for 24 hours. After the treatment, wash the catalyst to neutrality and dry it. Repeat the phosphoric acid treatment for a total of 3 times. Calcine the catalyst at 600°C for 6 hours to obtain a finished catalyst.

[0133] Comparative Example 4

[0134] A method for preparing a catalyst comprises the following steps:

[0135] (1) Prepare a 10% BaOH isopropanol solution and heat it to 90°C. Place the S-1 molecular sieve carrier in the strong alkaline solution for 10 hours. After the treatment, wash the carrier to neutrality and dry it. Repeat the alkaline treatment for a total of 2 times.

[0136] Prepare a 2% ammonium nitrate solution and heat it to 90°C. Place the alkali-treated carrier in the ammonium nitrate solution for 18 hours. After the treatment, wash the carrier to neutrality and dry it. Repeat the ammonium nitrate treatment for a total of 3 times. Calcine the carrier at 600°C for 10 hours.

[0137] (2) Prepare a 12% mixed salt solution of iron nitrate and manganese nitrate (iron:manganese atomic ratio 3:1), and heat it to 80°C. Place the carrier treated in step (1) in the metal salt solution for ion exchange treatment for 6 hours. After the treatment, wash the catalyst precursor to neutrality and dry it. Repeat the metal salt treatment for a total of 3 times. Calcine the catalyst precursor at 550°C for 11 hours.

[0138] (3) Prepare a 15% phosphoric acid solution and heat it to 90° C. Place the catalyst precursor obtained in step (2) in the phosphoric acid solution for treatment for 16 hours. After the treatment, wash the catalyst precursor to neutrality and dry it. Repeat the phosphoric acid treatment for a total of 4 times.

[0139] (4) Dissolve metasilicic acid in water, stir evenly, then add sodium aluminate, the atomic ratio of silicon to aluminum is 100, stir the liquid until it forms a uniform treatment liquid, the total mass of silicon source and aluminum source is 0.25 kg; place 1 kg of the catalyst precursor obtained in step (3) in the treatment liquid, mix evenly, heat water to 200° C. in a hydrothermal kettle, and perform hydrothermal treatment for 3 hours. After the treatment is completed, wash the catalyst to neutrality and dry it. Calcine the catalyst at 700° C. for 10 hours to obtain a finished catalyst.

[0140] Comparative Example 5

[0141] A method for preparing a catalyst comprises the following steps:

[0142] (1) A solution of magnesium nitrate with a concentration of 15% was prepared and heated to 50° C. The SAPO molecular sieve carrier was added to the metal salt solution and stirred for 12 hours until it was fully soaked. The molecular sieve soaked with the metal salt was then taken out and dried.

[0143] (2) Prepare a phosphoric acid solution with a concentration of 15%, heat it to 50°C, stir the solution and gradually add the molecular sieve treated in step (1) into the phosphoric acid solution, and stir for 24 hours after the addition. After the reaction is completed, wash the catalyst to neutrality, dry it, and then calcine it at 700°C for 10 hours to obtain a finished catalyst.

[0144] Comparative Example 6

[0145] A method for preparing a catalyst comprises the following steps: preparing a 15% magnesium nitrate solution and heating it to 50°C, gradually adding a 10% phosphoric acid solution to the magnesium nitrate solution until no new precipitation is generated, washing the generated solid catalyst with water until it is neutral, and drying it, and calcining the catalyst at 450°C for 12 hours to obtain a finished catalyst.

[0146] Test Case

[0147] The present invention tests the catalysts prepared in Examples 1-6 for synthesizing aminocapronitrile from caprolactam, and the finished catalysts prepared in Comparative Examples 1-6 for catalyzing the amination of caprolactam to prepare aminocapronitrile. The specific control conditions and test results are as follows.

[0148] Implementation of test case 1

[0149] A method for preparing aminocapronitrile, specifically: placing the catalyst obtained in Example 1 in a fixed bed reaction evaluation device for evaluation; the reaction temperature is 340°C, the reaction space velocity is 1.5h -1 The single-pass conversion rate of caprolactam was 72.97%, the yield of aminocapronitrile was 97.74%, and the catalyst life was 8150h.

[0150] Implementation of Test Example 2

[0151] A method for preparing aminocapronitrile, specifically: placing the catalyst obtained in Example 2 in a fixed bed reaction evaluation device for evaluation; the reaction temperature is 280°C, the reaction space velocity is 0.2h -1 The single-pass conversion rate of caprolactam was 52.28%, the yield of aminocapronitrile was 98.56%, and the catalyst life was 12040h.

[0152] Implementation of Test Case 3

[0153] A method for preparing aminocapronitrile, specifically: the catalyst obtained in Example 3 is placed in a fixed bed reaction evaluation device for evaluation; the reaction temperature is 310°C, the reaction space velocity is 1.2h -1 The single-pass conversion rate of caprolactam was 61.93%, the yield of aminocapronitrile was 96.87%, and the catalyst life was 6520h.

[0154] Implementation of Test Case 4

[0155] A method for preparing aminocapronitrile, specifically: placing the catalyst obtained in Example 4 in a fixed bed reaction evaluation device for evaluation; the reaction temperature is 400°C, the reaction space velocity is 4h -1 The single-pass conversion rate of caprolactam was 77.66%, the yield of aminocapronitrile was 97.06%, and the catalyst life was 5890h.

[0156] Implementation of Test Case 5

[0157] A method for preparing aminocapronitrile, specifically: the catalyst obtained in Example 5 is placed in a fixed bed reaction evaluation device for evaluation; the reaction temperature is 370°C, the reaction space velocity is 2.0h-1; the caprolactam single-pass conversion rate is 74.87%, the aminocapronitrile yield is 97.26%, and the catalyst life is 7630h.

[0158] Implementation of Test Case 6

[0159] A method for preparing aminocapronitrile, specifically: placing the catalyst obtained in Example 6 in a fixed bed reaction evaluation device for evaluation; the reaction temperature is 380°C, the reaction space velocity is 3.0h -1 The single-pass conversion rate of caprolactam was 71.08%, the yield of aminocapronitrile was 97.54%, and the catalyst life was 6850h.

[0160] Comparative test example 1

[0161] A method for preparing aminocapronitrile, specifically: placing the catalyst obtained in Comparative Example 1 in a fixed bed reaction evaluation device for evaluation; the reaction temperature is 340° C., the reaction space velocity is 1.5 h -1 The one-way conversion rate of caprolactam was 21.51%, and the yield of aminocapronitrile was 97.62%. The catalyst life of the present invention is evaluated by the one-way conversion rate of the raw material. In the comparative test example, the one-way conversion rate of caprolactam is relatively low, so the catalyst life does not require conventional testing.

[0162] Comparative test example 2

[0163] A method for preparing aminocapronitrile, specifically: placing the catalyst obtained in Comparative Example 2 in a fixed bed reaction evaluation device for evaluation; the reaction temperature is 280° C., the reaction space velocity is 0.2 h -1 The one-way conversion rate of caprolactam is 12.28%, and the yield of aminocapronitrile is 97.12%. The catalyst life of the present invention is evaluated by the one-way conversion rate of the raw material. In the comparative test example, the one-way conversion rate of caprolactam is relatively low, so the catalyst life does not need to be routinely tested.

[0164] Comparative test example 3

[0165] A method for preparing aminocapronitrile, specifically: placing the catalyst obtained in Comparative Example 3 in a fixed bed reaction evaluation device for evaluation; the reaction temperature is 310° C., the reaction space velocity is 1.2 h -1 It was found that the single-pass conversion rate of caprolactam was 65.31%, the yield of aminocapronitrile was 97.15%, and the catalyst life was 1400h.

[0166] Comparative test example 4

[0167] A method for preparing aminocapronitrile, specifically: placing the catalyst obtained in Comparative Example 4 in a fixed bed reaction evaluation device for evaluation; the reaction temperature is 400° C., the reaction space velocity is 4 h -1 The single-pass conversion rate of caprolactam was 51.73%, the yield of aminocapronitrile was 93.74%, and the catalyst life was 1520h.

[0168] Comparative test example 5

[0169] A method for preparing aminocapronitrile, specifically: the catalyst obtained in comparative example 5 is placed in a fixed bed reaction evaluation device for evaluation; the reaction temperature is 360°C, the reaction space velocity is 1.5h -1 The single-pass conversion rate of caprolactam was 69.41%, the yield of aminocapronitrile was 97.12%, and the catalyst life was 920h.

[0170] Comparative test example 6

[0171] A method for preparing aminocapronitrile, specifically: placing the catalyst obtained in Comparative Example 6 in a fixed bed reaction evaluation device for evaluation; the reaction temperature is 370° C., the reaction space velocity is 2.0 h -1 The single-pass conversion rate of caprolactam was 62.86%, the yield of aminocapronitrile was 96.85%, and the catalyst life was 2220h.

[0172] It should be noted that the above contents are further detailed descriptions of the present invention in combination with specific implementation methods, and it cannot be determined that the specific implementation of the present invention is limited to these descriptions; the dimensional data of this embodiment does not limit the technical solution, but only shows one of the specific working conditions. For ordinary technicians in the technical field to which the present invention belongs, several simple improvements and modifications can be made without departing from the concept of the present invention, which should be regarded as falling within the scope of protection of the present invention.

Claims

1. A method for preparing a catalyst for synthesizing aminocapronitrile from caprolactam, characterized in that: The following steps are involved: (1) treating the molecular sieve carrier with alkali and exchanging with ammonium, and calcining the carrier to obtain a pretreated carrier; (2) placing the pretreated support in a metal salt solution for ion exchange to obtain a first catalyst precursor; (3) treating the first catalyst precursor with phosphoric acid to obtain a second catalyst precursor; (4) placing the second catalyst precursor in a treatment solution containing a silicon source and an aluminum source, and subjecting the treatment to hydrothermal treatment to obtain a third catalyst precursor; (5) The third catalyst precursor is acid-washed to obtain the catalyst for synthesizing aminocapronitrile from caprolactam.

2. The method for preparing a catalyst for synthesizing aminocapronitrile from caprolactam according to claim 1, characterized in that: The molecular sieve carrier includes at least one of S-1 molecular sieve, ZSM-5 molecular sieve, β molecular sieve, Y molecular sieve, mordenite molecular sieve, SAPO molecular sieve and MCM molecular sieve.

3. The method for preparing a catalyst for synthesizing aminocapronitrile from caprolactam according to claim 1, characterized in that: The alkali treatment in step (1) comprises: contacting the molecular sieve support with an alkali solution; Preferably, the alkali used for the alkali treatment includes one of lithium hydroxide, sodium hydroxide, potassium hydroxide, barium hydroxide, and calcium hydroxide; Preferably, the solvent of the alkaline solution includes one of water, methanol, ethanol, isopropanol, and tert-butanol; Preferably, the mass concentration of the alkaline solution is 2 to 50%; Preferably, the temperature of the alkali treatment is 30 to 120° C., and the treatment time is 2 to 10 hours; Preferably, the alkali treatment is performed 1 to 5 times.

4. The method for preparing a catalyst for synthesizing aminocapronitrile from caprolactam according to claim 1, characterized in that: The ammonium exchange comprises: contacting the alkali-treated carrier with an ammonium nitrate solution; Preferably, the mass concentration of the ammonium nitrate solution is 1 to 10%; Preferably, the temperature of the ammonium exchange is 30 to 120° C., and the treatment time is 6 to 24 hours; Preferably, the number of ammonium exchanges is 1 to 5 times.

5. The method for preparing a catalyst for synthesizing aminocapronitrile from caprolactam according to claim 1, characterized in that: In step (2), the metal salt solution is prepared by dissolving a metal salt in water; Preferably, the cation of the metal salt comprises Ni 2+ 、Co 2+ 、Ce 3+ , Fe 3+ Mg 2+ ,La + , Mn 4+ 、Zn 2+ At least one of; Preferably, the anion of the metal salt includes at least one of nitrate, formate, acetate and benzoate; Preferably, the mass concentration of the metal salt solution is 1 to 20%; Preferably, the ion exchange temperature is 30 to 120° C., and the treatment time is 2 to 10 hours; Preferably, the number of ion exchanges is 1 to 5 times; Preferably, the step (2) further comprises washing and calcining the catalyst precursor after ion exchange; Preferably, the calcination temperature is 400-800° C. and the calcination time is 4-12 hours.

6. The method for preparing a catalyst for synthesizing aminocapronitrile from caprolactam according to claim 1, characterized in that: The phosphoric acid treatment in step (3) comprises: contacting the first catalyst precursor with a phosphoric acid solution; Preferably, the mass concentration of the phosphoric acid solution is 5-20%; Preferably, the phosphoric acid treatment is carried out at a temperature of 30 to 100° C. and for a treatment time of 8 to 24 hours.

7. The method for preparing a catalyst for synthesizing aminocapronitrile from caprolactam according to claim 1, characterized in that: In the step (4), the silicon source includes at least one of 30% silica sol, tetraethyl orthosilicate, fumed silicon oxide, silicic acid, and metasilicic acid; And / or, in the step (4), the aluminum source comprises at least one of 20% aluminum sol, pseudo-boehmite, sodium aluminate, and γ-alumina; And / or, in step (4), the atomic ratio of silicon to aluminum in the treatment solution is 10 to 100; And / or, in the step (4), the mass ratio of the sum of the mass of the silicon source and the aluminum source in the treatment liquid to the mass of the second catalyst precursor is (0.2-1):1; And / or, in step (4), the temperature of the hydrothermal treatment is 120-200° C., and the time of the hydrothermal treatment is 2-12 hours.

8. The method for preparing a catalyst for synthesizing aminocapronitrile from caprolactam according to claim 1, characterized in that: The step (5) of acid washing comprises: contacting the third catalyst precursor with an acid; Preferably, the acid comprises at least one of nitric acid, sulfuric acid, hydrochloric acid, oxalic acid, and citric acid; Preferably, the mass concentration of the acid is 10-50%; Preferably, the pickling temperature is 30 to 100°C and the treatment time is 2 to 12 hours; Preferably, the step (5) further comprises washing and calcining the catalyst precursor after acid washing; Preferably, the calcination temperature is 400-800° C., and the calcination time is 4-12 hours.

9. A catalyst for synthesizing aminocapronitrile from caprolactam, characterized in that The catalyst is prepared by the preparation method according to any one of claims 1 to 8.

10. Use of the catalyst for synthesizing aminocapronitrile from caprolactam according to claim 9 in preparing aminocapronitrile by ammoniation using caprolactam as a raw material.

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