A catalyst for preparing 6-aminocapronitrile and a preparation method thereof

Abstract

The present invention discloses a catalyst for preparing 6 - aminohexanenitrile and a preparation method thereof. The catalyst has a core of an active component, and a dehydration aid is in - situ crystallized into a shell on the surface of the core, and has a pore structure in the shell or the core - shell; the active component is selected from one or more of zirconia, silica, magnesia, alumina, titania, boron oxide, zinc oxide, and lanthanum oxide; the dehydration aid is a weakly acidic molecular sieve; calculated by mass percentage, the active component accounts for 10 - 99% of the catalyst. The present invention adopts the in - situ crystallization technology, adds a molecular sieve with extremely weak acidity that can rapidly adsorb and desorb water at high temperature to prepare a composite catalyst in the active component, accelerates the desorption rate of the reaction products water and 6 - aminohexanenitrile on the active sites, promotes the forward progress of the ammoniation reaction, thereby improving the conversion rate and selectivity of caprolactam, and increasing the catalyst life.

Description

Technical Field

[0001] The present invention relates to the technical field of catalytic preparation of 6 - aminocapronitrile, and particularly to a catalyst for preparing 6 - aminocapronitrile and a preparation method thereof. Background Art

[0002] 6 - Aminocapronitrile is an important organic chemical, mainly used for the production of hexamethylenediamine, and then for the production of polymers such as nylon 66. The methods for producing 6 - aminocapronitrile mainly include the liquid - phase method and the gas - phase method of caprolactam ammoniation. In the liquid - phase method, the conversion rate of caprolactam is relatively low, the catalyst recovery is difficult, and the cost is high, which is not suitable for large - scale production. In the gas - phase method, the conversion rate of caprolactam is mostly between 50% and 80%, and the selectivity of 6 - aminocapronitrile is mostly between 92% and 98%. The water generated during the ammoniation reaction is difficult to desorb from the active sites of the catalyst, which limits the further improvement of the caprolactam conversion rate. CN 111659463 A uses a silicoaluminophosphate molecular sieve with a specific silicon - aluminum - phosphorus molar ratio to facilitate the hydrolysis ammoniation and dehydration of caprolactam. However, such molecular sieves have strong acidity. Although the caprolactam conversion rate is relatively high, it is not conducive to the desorption of the reaction product 6 - aminocapronitrile from the active sites, resulting in low selectivity and easy carbon deposition deactivation. Summary of the Invention

[0003] Aiming at the technical problems in the prior art, such as low caprolactam conversion rate, low selectivity of the target product 6 - aminocapronitrile, and short catalyst life due to the adsorption of water generated on the catalyst surface, the present invention provides a catalyst and a preparation method thereof. In the reaction of caprolactam with ammonia to prepare 6 - aminocapronitrile, the catalyst facilitates the rapid desorption of the reaction products water and 6 - aminocapronitrile from the active sites, and has the characteristics of high conversion rate, high selectivity, high stability, and less carbon deposition.

[0004] Specifically, the technical solution of the present invention is as follows:

[0005] In the first aspect, the present invention provides a catalyst for the reaction of caprolactam with ammonia to prepare 6 - aminocapronitrile, which has an active component as the core, and a dehydration aid is in - situ crystallized into a shell on the surface of the core, and has a pore structure in the shell or the core - shell; the active component is selected from one or more of zirconia, silica, magnesia, alumina, titania, boron oxide, zinc oxide, and lanthanum oxide; the dehydration aid is a weakly acidic molecular sieve; calculated by mass percentage, the active component accounts for 10 - 99% of the catalyst.

[0006] In a specific embodiment, the weakly acidic molecular sieve is selected from one or more of 3A, 4A, and 5A, and preferably 3A molecular sieve.

[0007] In a specific embodiment, the active component is selected from ZrO 2 、SiO 2 、MgO、A1 2O 3 、TiO 2 。

[0008] In a specific embodiment, by mass percentage, the active component accounts for 40-90% of the catalyst, preferably 50-85%.

[0009] In a specific embodiment, the surface pore diameter of the catalyst is 5-30 nm.

[0010] In a second aspect, the present invention provides a method for preparing the above-mentioned catalyst for the reaction of caprolactam with ammonia to prepare 6-aminocapronitrile. The preparation method adopts an in-situ crystallization method and includes the following steps:

[0011] (1) At 50-60 °C, a soluble compound solution A of active elements zirconium, silicon, boron, magnesium, zinc, lanthanum, titanium, and aluminum and an aqueous precipitant solution B are slowly added dropwise to an ethanol solution C of a dispersant for precipitation reaction. During the precipitation process, the pH value is controlled at 4-10. After precipitation, stirring is continued for 0.5-2 hours, followed by standing, aging at room temperature for 8-24 hours, or crystallizing at 110-250 °C for 1-48 hours. Then, filtration, washing, and drying are carried out to obtain a catalyst active component precursor a; wherein, the dosage ratio of the active element: precipitant: dispersant is 1 mol: 0.5-10 mol: 1-6 g, and the volume ratio of the solution A: solution B: solution C is 0.5-5 L: 0.1-2 L: 10-30 mL;

[0012] (2) An aqueous solution D of sodium aluminate and sodium hydroxide and an aqueous solution E of sodium metasilicate and sodium hydroxide are rapidly mixed, the catalyst active component precursor a is added, and stirring is carried out until a thick gel is formed. Then, crystallization, filtration, washing, drying, and calcination at 450-700 °C for 1-24 hours are carried out to obtain product b;

[0013] (3) After the product b is subjected to ion exchange with an aqueous solution of KCl or CaCl 2 , filtration, washing, and drying are carried out to obtain product c;

[0014] (4) The product b or product c is taken, mixed with a pore-forming agent and a 5-68 wt% HNO 3 aqueous solution, kneaded, extruded into strips, dried, calcined at 300-750 °C for 1-24 hours, and cooled to obtain the catalyst; wherein, the dosage ratio of the product b or product c: pore-forming agent: 5-68 wt% HNO 3 aqueous solution is 200-1000 g: 10-300 g: 2-300 g.

[0015] In a specific embodiment, in step (1):

[0016] The soluble compound of the active element is selected from Zr(NO3 ) 4 , tetraethyl orthosilicate, Mg(NO 3 ) 2 , Al(NO 3 ) 3 , TiCl 4 . In particular, when Zr(NO 3 ) 4 is used as the active component, in the reaction of caprolactam with ammonia to prepare 6-aminocapronitrile, the conversion rate of caprolactam and the selectivity of 6-aminocapronitrile have better catalytic effects.

[0017] The solvent of the soluble compound solution A of the active element is water or an ethanol-aqueous solution. In particular, when the soluble compound of the active element is tetraethyl orthosilicate, the solvent of solution A is an ethanol-aqueous solution, preferably 75% (v / v) ethanol aqueous solution.

[0018] The precipitant is selected from one or more of sodium carbonate, sodium hydroxide, and ammonia, and is used to form hydroxide precipitates / basic carbonates, which will turn into oxide forms after calcination.

[0019] The dispersant is selected from dodecyltrimethylammonium bromide, dodecyltrimethylammonium chloride, cetyltrimethylammonium bromide, cetyltrimethylammonium chloride, octadecyltrimethylammonium bromide, octadecyltrimethylammonium chloride, tetramethylammonium hydroxide, and tetrabutylammonium bromide; preferably selected from cetyltrimethylammonium bromide, cetyltrimethylammonium chloride, tetramethylammonium hydroxide, and tetrabutylammonium bromide.

[0020] The dosage ratio of the active element: precipitant: dispersant is: 1 mol: 1-7 mol: 1-6 g; the volume ratio of solution A: solution B: solution C is: 2-3 L: 0.5-1 L: 15-25 mL.

[0021] The pH value during the precipitation process is controlled at 6-8, preferably 7-7.5.

[0022] The stirring time after the precipitation is continued for 0.8-1.5 hours, preferably 1 hour.

[0023] The aging time at room temperature is 10-14 hours, preferably 12 hours.

[0024] In a specific embodiment, in step (2):

[0025] The dosage ratio of the catalyst active component precursor a: sodium aluminate: sodium metasilicate is: 250-1200 g: 50-120 g: 80-200 g, preferably 400-600 g: 60-100 g: 120-180 g, such as 560 g: 82.58 g: 154.8 g.

[0026] The crystallization temperature is 60 to 140 °C, preferably 90 to 110 °C, such as 99 °C, and the crystallization time is 1 to 48 hours, preferably 2 to 8 hours, such as 4 hours.

[0027] The calcination temperature is 450 to 650 °C and the time is 6 to 12 hours. Calcination after in-situ crystallization of the molecular sieve can enhance the binding force between the molecular sieve and the active component. Low-temperature calcination will result in weak binding force between the active component and the molecular sieve. The molecular sieve layer covers the outside of the active component core, showing a poreless or small-pore situation. This pore structure has no effect on the diffusion of water, but limits the adsorption and desorption of raw material caprolactam and product aminocapronitrile, especially the desorption of high-carbon products is extremely difficult; therefore, too low a calcination temperature will not only reduce the catalyst activity but also make the catalyst prone to coking and deactivation. While too high a calcination temperature will cause catalyst sintering, grain growth, small specific surface area, and reduced activity.

[0028] The present invention prepares different types of molecular sieves by the ion exchange method. In a specific embodiment, the product b prepared in step (2) can be directly subjected to step (4) to prepare a catalyst with 4A molecular sieve as the dehydration aid. After the product b is subjected to ion exchange with an aqueous solution of KCl or CaCl 2 in step (3), catalysts with 3A or 5A molecular sieve as the dehydration aid can be formed respectively. Specifically, in step (3), the concentration of the aqueous solution of KCl or CaCl 2 is 0.6 to 0.8 mol / L; the ion exchange temperature is 40 to 90 °C, preferably 70 to 90 °C, more preferably 80 °C, and the ion exchange time is 0.1 to 2.5 hours, preferably 1 to 2 hours, preferably 2 hours.

[0029] In a specific embodiment, in step (4),

[0030] The pore-forming agent is selected from one or more of polyacrylamide, polyvinyl alcohol, polyethylene glycol, sesbania powder, carbon black, polyethylene oxide, carboxymethyl cellulose, etc.

[0031] The concentration of the aqueous solution of HNO 3 is 20 to 68 wt%.

[0032] The dosage ratio of the product b or product c: pore-forming agent: 5-68% aqueous solution of HNO 3 is: 500 g: 30 to 60 g: 8 to 30 g.

[0033] The calcination temperature is 450-600°C, and the calcination time is 4-12 hours. A calcination temperature higher than this will cause the catalyst to sinter, the crystal grains to grow, the specific surface area to be small, and the activity to be low; while a too low calcination temperature will cause incomplete decomposition of the pore-forming agent, resulting in no pore-forming effect and poor catalyst activity.

[0034] In a specific embodiment, in steps (1)-(4), the drying temperature is 90-130°C, preferably 100-120°C, and more preferably 110°C.

[0035] In the third aspect of the present invention, a method for preparing 6-aminocapronitrile by reacting caprolactam with ammonia is provided, which catalyzes the reaction of caprolactam with ammonia in the presence of the above catalyst (i.e., the catalyst of the present invention or the catalyst prepared according to the preparation method of the present invention).

[0036] In a specific embodiment, the temperature for the catalyst to catalyze the reaction of caprolactam with ammonia is 340-400°C; preferably 340-380°C;

[0037] The molar ratio of ammonia to caprolactam is 8-50, preferably 12-30.

[0038] Beneficial effects

[0039] The present invention adopts the in-situ crystallization technology to prepare a composite catalyst by adding a molecular sieve with extremely weak acidity that can rapidly adsorb and desorb water at high temperature to the active component, which speeds up the desorption rate of the reaction products water and 6-aminocapronitrile from the active sites, promotes the forward progress of the ammoniation reaction, and thus improves the conversion rate of caprolactam. Since the molecular sieve used has extremely weak acidity, caprolactam will not undergo an ammoniation reaction on its surface, and 6-aminocapronitrile has weak adsorption on the molecular sieve surface, and its desorption from the active sites will not be restricted. Therefore, while improving the conversion rate of caprolactam, the selectivity of 6-aminocapronitrile is also slightly increased, and the generation amount of other by-products such as high-carbon compounds that are not easily desorbed is reduced, thereby improving the service life of the catalyst.

[0040] The present invention selects the active component of the catalyst and controls the dosage ratio of the precursor of the active component of the catalyst to the precursor of the dehydration aid to facilitate the rapid removal of water, one of the products, from the catalytic active sites. By controlling the calcination temperature and time, the surface pore structure of the catalyst is controlled to make its surface pore diameter appropriate (about 5-30 nm) to facilitate the rapid removal of the other main product 6-aminocapronitrile from the catalytic active sites, greatly improving the conversion rate of caprolactam and also improving the selectivity of 6-aminocapronitrile. Brief description of the drawings

[0041] Figure 1 It is a schematic structural diagram of the catalyst in the embodiment of the present invention.

[0042] Figure 2 The experimental results of the 1000 - hour stability of Catalyst 1 in Example 1. Detailed implementation manners

[0043] It should be noted that, without conflict, the implementation manners in the present invention and the features in the implementation manners can be combined with each other. The technical solutions of the present invention are not limited to the following specific implementation manners listed, but also include any combination between the specific implementation manners.

[0044] In the present invention, unless otherwise specified, the reagents used can be obtained through regular commercial purchase, and the equipment and testing methods used are all conventional equipment and methods in the art.

[0045] Example 1

[0046] A preparation method of a catalyst for the reaction of caprolactam with ammonia to prepare 6 - aminocapronitrile, comprising the following steps:

[0047] (1) Add 429 g of Zr(NO 3 ) 4 ·5H 2 O to 3 L of water, and stir until a clear solution is formed; dissolve 318 g of Na 2 CO 3 in 1 L of water; dissolve 4 g of cetyltrimethylammonium bromide in 20 mL of ethanol;

[0048] (2) At 60 °C, slowly add the above - mentioned Zr(NO 3 ) 4 solution and Na 2 CO 3 solution drop - by - drop into the ethanol solution of cetyltrimethylammonium bromide for precipitation reaction. During the precipitation process, the pH value is controlled at about 7.0. After the precipitation is completed, continue to stir for 1 hour, let it stand, age at room temperature for 12 hours, filter, wash, and dry at 110 °C to obtain the precursor a of the catalyst active component;

[0049] (3) Dissolve 3.615 g of NaOH in 1 L of deionized water, and then add 82.58 g of sodium aluminate and stir evenly; dissolve 3.615 g of NaOH in 1 L of deionized water, and then add 154.8 g of sodium metasilicate and stir evenly; quickly mix the solution of sodium aluminate and NaOH with the solution of sodium metasilicate and NaOH, add 560 g of the precursor a of the catalyst active component described in step (2), stir until a thick gel is formed, place it in a hydrothermal reaction kettle, crystallize at 99 ± 1 °C for 4 hours, filter, wash, dry at 110 °C, and calcine at 650 °C for 12 hours to obtain product b;

[0050] (4) The KCl solution with a concentration of 0.6 mol / L is used for ion exchange with the product b obtained in step (3): at a temperature of 80 °C, the exchange is carried out for 2 hours, then filtered, washed, and dried at 110 °C to obtain product c;

[0051] (5) Take 500 g of product c obtained in step (4), add 40 g of polyacrylamide, and then add 10 g of 68% HNO 3 After mixing, knead, extrude, dry, and calcine at 500 °C for 12 hours, and cool to obtain a cylindrical 3A molecular sieve - ZrO 2 Composite catalyst.

[0052] Example 2

[0053] A preparation method of a catalyst for the reaction of caprolactam with ammonia to prepare 6 - aminocapronitrile, comprising the following steps:

[0054] (1) Add 429 g of Zr(NO 3 ) 4 ·5H 2 O to 3 L of water and stir until a clear solution is formed; dissolve 318 g of Na 2 CO 3 in 1 L of water; dissolve 4 g of cetyltrimethylammonium bromide in 20 mL of ethanol;

[0055] (2) At 60 °C, slowly add the above Zr(NO 3 ) 4 solution and Na 2 CO 3 solution dropwise to the ethanol solution of cetyltrimethylammonium bromide for precipitation reaction. During the precipitation process, the pH value is controlled at about 7.0. After precipitation, continue to stir for 1 hour, let stand, age at room temperature for 12 hours, filter, wash, and dry at 110 °C to obtain the precursor a of the catalyst active component;

[0056] (3) Dissolve 3.615 g of NaOH in 1 L of deionized water, then add 82.58 g of sodium aluminate and stir evenly; dissolve 3.615 g of NaOH in 1 L of deionized water, then add 154.8 g of sodium metasilicate and stir evenly; quickly mix the solution of sodium aluminate and NaOH, and the solution of sodium metasilicate and NaOH, add 560 g of the precursor a of the catalyst active component described in step (2), stir until a thick gel is formed, place it in a hydrothermal reaction kettle, and crystallize at 99 ± 1 °C for 4 hours, filter, wash, dry at 110 °C, and calcine at 450 °C for 12 hours to obtain product b;

[0057] (4) The KC1 solution with a concentration of 0.6 mol / L is used for ion exchange with the product b obtained in step (3): at a temperature of 80 °C, exchange for 2 hours, then filter, wash, and dry at 110 °C;

[0058] (5) Take 500 g of the product c in step (4), add 40 g of polyethylene glycol, and then add 10 g of 68% HNO 3 After mixing, knead, extrude into strips, dry, and calcine at 500 °C for 12 hours. After cooling, a cylindrical 3A molecular sieve - ZrO 2 composite catalyst is obtained.

[0059] Example 3

[0060] A preparation method of a catalyst for the reaction of caprolactam with ammonia to prepare 6 - aminocapronitrile, comprising the following steps:

[0061] (1) Add 429 g of Zr(NO 3 ) 4 ·5H 2 O to 3 L of water and stir until a clear solution is formed; dissolve 318 g of Na 2 CO 3 in 1 L of water; dissolve 4 g of cetyltrimethylammonium bromide in 20 mL of ethanol;

[0062] (2) At 60 °C, slowly add the above Zr(NO 3 ) 4 solution and the Na 2 CO 3 solution dropwise to the ethanol solution of cetyltrimethylammonium bromide for precipitation reaction. During the precipitation process, the pH value is controlled at about 7.0. After precipitation, continue to stir for 1 hour, let stand, age at room temperature for 12 hours, filter, wash, and dry at 110 °C to obtain the precursor a of the catalyst active component;

[0063] (3) Dissolve 3.615 g of NaOH in 1 L of deionized water, then add 82.58 g of sodium aluminate and stir evenly; dissolve 3.615 g of NaOH in 1 L of deionized water, then add 154.8 g of sodium metasilicate and stir evenly; quickly mix the sodium aluminate and NaOH solution with the sodium metasilicate and NaOH solution, add 560 g of the precursor a of the catalyst active component obtained in step (2), stir until a thick gel is formed, place it in a hydrothermal reaction kettle and crystallize at 99 ± 1 °C for 4 hours, filter, wash, dry at 110 °C, and calcine at 450 °C for 12 hours to obtain the product b;

[0064] (4) Prepare a KCl solution with a concentration of 0.6 mol / L for ion exchange with the product b obtained in step (3): at a temperature of 80 °C, exchange for 2 hours, then filter, wash, and dry at 110 °C;

[0065] (5) Take 500 g of product c in step (4), add 40 g of polyvinyl alcohol, and then add 10 g of 68% HNO 3 After mixing, knead, extrude, dry, calcine at 600 °C for 12 hours, and after cooling, cylindrical 3A molecular sieve-ZrO 2 Composite catalyst.

[0066] Example 4

[0067] A preparation method of a catalyst for the reaction of caprolactam with ammonia to prepare 6-aminocapronitrile, comprising the following steps:

[0068] (1) Add 429 g of Zr(NO 3 ) 4 ·5H 2 O to 3 L of water and stir until a clear solution is formed; dissolve 318 g of Na 2 CO 3 in 1 L of water; dissolve 4 g of cetyltrimethylammonium bromide in 20 mL of ethanol;

[0069] (2) At 60 °C, slowly add the above Zr(NO 3 ) 4 solution and Na 2 CO 3 solution dropwise to the ethanol solution of cetyltrimethylammonium bromide for precipitation reaction. During the precipitation process, the pH value is controlled at about 7.0. After the precipitation is completed, continue to stir for 1 hour, let stand, age at room temperature for 12 hours, filter, wash, and dry at 110 °C to obtain the precursor a of the catalyst active component;

[0070] (3) Dissolve 3.615 g of NaOH in 1 L of deionized water, then add 82.58 g of sodium aluminate and stir evenly; dissolve 3.615 g of NaOH in 1 L of deionized water, then add 154.8 g of sodium metasilicate and stir evenly; quickly mix the solution of sodium aluminate and NaOH and the solution of sodium metasilicate and NaOH, add 280 g of the precursor a of the catalyst active component described in step (2), stir until a thick gel is formed, place it in a hydrothermal reaction kettle, and crystallize at 99 ± 1 °C for 4 hours, filter, wash, dry at 110 °C, and calcine at 450 °C for 12 hours to obtain product b;

[0071] (4) Configure a KCl solution with a concentration of 0.6 mol / L and perform ion exchange with product b obtained in step (3): at a temperature of 80 °C, exchange for 2 hours, then filter, wash, and dry at 110 °C;

[0072] (5) Take 500 g of product c in step (4), add 40 g of polyethylene glycol, and then add 10 g of 68% HNO3 Mix and knead, extrude, dry, calcine at 500 °C for 12 hours, and obtain cylindrical 3A molecular sieve-ZrO after cooling 2 composite catalyst.

[0073] Example 5

[0074] A preparation method of a catalyst for the reaction of caprolactam with ammonia to prepare 6-aminocapronitrile, comprising the following steps:

[0075] (1) Add 429 g of Zr(NO 3 ) 4 ·5H 2 O to 3 L of water, stir until a clear solution is formed; dissolve 318 g of Na 2 CO 3 in 1 L of water; dissolve 4 g of cetyltrimethylammonium bromide in 20 mL of ethanol;

[0076] (2) At 60 °C, slowly add the above Zr(NO 3 ) 4 solution and Na 2 CO 3 solution dropwise to the ethanol solution of cetyltrimethylammonium bromide for precipitation reaction. During the precipitation process, the pH value is controlled at about 7.0. After the precipitation is completed, continue to stir for 1 hour, let stand, age at room temperature for 12 hours, filter, wash, and dry at 110 °C to obtain the precursor a of the catalyst active component;

[0077] (3) Dissolve 3.615 g of NaOH in 1 L of deionized water, then add 82.58 g of sodium aluminate and stir evenly; dissolve 3.615 g of NaOH in 1 L of deionized water, then add 154.8 g of sodium metasilicate and stir evenly; quickly mix the solution of sodium aluminate and NaOH with the solution of sodium metasilicate and NaOH, add 1200 g of the precursor a of the catalyst active component obtained in step (2), stir until a thick gel is formed, place it in a hydrothermal reaction kettle, and crystallize at 99 ± 1 °C for 4 hours, filter, wash, dry at 110 °C, and calcine at 450 °C for 12 hours to obtain product b;

[0078] (4) Configure a 0.6 mol / L KC1 solution to perform ion exchange with product b obtained in step (3): at a temperature of 80 °C, exchange for 2 hours, then filter, wash, and dry at 110 °C;

[0079] (5) Take 500 g of product c in step (4), add 40 g of polyvinyl alcohol, and then add 10 g of 68% HNO 3 Mix and knead, extrude, dry, calcine at 600 °C for 12 hours, and obtain cylindrical 3A molecular sieve-ZrO 2 composite catalyst.

[0080] Example 6

[0081] A preparation method of a catalyst for the reaction of caprolactam with ammonia to prepare 6 - aminocapronitrile, comprising the following steps:

[0082] (1) Add 429 g of Zr(NO 3 ) 4 ·5H 2 O to 3 L of water and stir until a clear solution is formed; dissolve 318 g of Na 2 CO 3 in 1 L of water; dissolve 4 g of cetyltrimethylammonium bromide in 20 mL of ethanol;

[0083] (2) At 60 °C, slowly add the above Zr(NO 3 ) 4 solution and Na 2 CO 3 solution dropwise to the ethanol solution of cetyltrimethylammonium bromide for precipitation reaction. During the precipitation process, the pH value is controlled at about 7.0. After precipitation, continue to stir for 1 hour, let stand, age at room temperature for 12 hours, filter, wash, and dry at 110 °C to obtain the precursor a of the catalyst active component;

[0084] (3) Dissolve 3.615 g of NaOH in 1 L of deionized water, then add 82.58 g of sodium aluminate and stir evenly; dissolve 3.615 g of NaOH in 1 L of deionized water, then add 154.8 g of sodium metasilicate and stir evenly; quickly mix the sodium aluminate and NaOH solution with the sodium metasilicate and NaOH solution, add 1200 g of the precursor a of the catalyst active component obtained in step (2), stir until a thick gel is formed, place it in a hydrothermal reaction kettle and crystallize at 99 ± 1 °C for 4 hours, filter, wash, dry at 110 °C, and calcine at 700 °C for 12 hours to obtain product b;

[0085] (4) Configure a KCl solution with a concentration of 0.6 mol / L and perform ion exchange with product b obtained in step (3): at a temperature of 80 °C, exchange for 2 hours, then filter, wash, and dry at 110 °C;

[0086] (5) Take 500 g of product c in step (4), add 40 g of polyvinyl alcohol, then add 10 g of 68% HNO 3 mix and knead, extrude into strips, dry, calcine at 500 °C for 12 hours, and cool to obtain a cylindrical 3A molecular sieve - ZrO 2 composite catalyst.

[0087] Example 7

[0088] A preparation method of a catalyst for the reaction of caprolactam with ammonia to prepare 6 - aminocapronitrile, comprising the following steps:

[0089] (1) Add 429 g of Zr(NO 3 ) 4 ·5H 2 O to 3 L of water and stir until a clear solution is formed; dissolve 318 g of Na 2 CO 3 in 1 L of water; dissolve 4 g of cetyltrimethylammonium bromide in 20 mL of ethanol;

[0090] (2) At 60 °C, slowly add the above Zr(NO 3 ) 4 solution and Na 2 CO 3 solution dropwise to the ethanol solution of cetyltrimethylammonium bromide for precipitation reaction. During the precipitation process, control the pH value at about 7.0. After precipitation, continue to stir for 1 hour, let it stand, age at room temperature for 12 hours, filter, wash, and dry at 110 °C to obtain the precursor a of the catalyst active component;

[0091] (3) Dissolve 3.615 g of NaOH in 1 L of deionized water, then add 82.58 g of sodium aluminate and stir evenly; dissolve 3.615 g of NaOH in 1 L of deionized water, then add 154.8 g of sodium metasilicate and stir evenly; quickly mix the sodium aluminate and NaOH solution with the sodium metasilicate and NaOH solution, add 1200 g of the precursor a of the catalyst active component obtained in step (2), stir until a thick gel is formed, place it in a hydrothermal reaction kettle and crystallize at 99 ± 1 °C for 4 hours, filter, wash, dry at 110 °C, and calcine at 650 °C for 12 hours to obtain product b;

[0092] (4) Configure a KCl solution with a concentration of 0.6 mol / L and perform ion exchange with product b obtained in step (3): at a temperature of 80 °C, exchange for 2 hours, then filter, wash, and dry at 110 °C;

[0093] (5) Take 500 g of product c in step (4), add 40 g of polyvinyl alcohol, then add 10 g of 68% HNO 3 mix and knead, extrude into strips, dry, calcine at 750 °C for 12 hours, and cool to obtain a cylindrical 3A molecular sieve - ZrO 2 composite catalyst.

[0094] Example 8

[0095] A preparation method of a catalyst for the reaction of caprolactam with ammonia to prepare 6 - aminocapronitrile, comprising the following steps:

[0096] (1) Add 429 g of Zr(NO 3 ) 4 ·5H 2 O to 3 L of water and stir until a clear solution is formed; dissolve 318 g of Na 2 CO 3 in 1 L of water; dissolve 4 g of cetyltrimethylammonium bromide in 20 mL of ethanol;

[0097] (2) At 60 °C, slowly add the above Zr(NO 3 ) 4 solution and Na 2 CO 3 solution dropwise to the ethanol solution of cetyltrimethylammonium bromide for precipitation reaction. During the precipitation process, control the pH value at about 7.0. After precipitation, continue to stir for 1 hour, let stand, age at room temperature for 12 hours, filter, wash, and dry at 110 °C to obtain the precursor a of the catalyst active component;

[0098] (3) Dissolve 3.615 g of NaOH in 1 L of deionized water, then add 82.58 g of sodium aluminate and stir evenly; dissolve 3.615 g of NaOH in 1 L of deionized water, then add 154.8 g of sodium metasilicate and stir evenly; quickly mix the solution of sodium aluminate and NaOH, and the solution of sodium metasilicate and NaOH, add 1200 g of the precursor a of the catalyst active component obtained in step (2), stir until a thick gel is formed, place it in a hydrothermal reaction kettle and crystallize at 99 ± 1 °C for 4 hours, filter, wash, dry at 110 °C, and calcine at 650 °C for 12 hours to obtain product b;

[0099] (4) Prepare a KCl solution with a concentration of 0.6 mol / L and perform ion exchange with product b obtained in step (3): At a temperature of 80 °C, exchange for 2 hours, then filter, wash, and dry at 110 °C;

[0100] (5) Take 500 g of product c in step (4), add 40 g of polyvinyl alcohol, then add 10 g of 68% HNO 3 mix and knead, extrude into strips, dry, calcine at 400 °C for 12 hours, and cool to obtain a cylindrical 3A molecular sieve-ZrO 2 composite catalyst.

[0101] Example 9

[0102] A preparation method of a catalyst for the reaction of caprolactam with ammonia to prepare 6-aminocapronitrile, using the following method steps:

[0103] (1) Add 208 g of tetraethyl orthosilicate to 3 L of 75% ethanol aqueous solution and stir evenly; dissolve 500 g of 25% ammonia water in 0.5 L of water; dissolve 2 g of cetyltrimethylammonium bromide in 20 mL of ethanol;

[0104] (2) At 50 °C, slowly add the above tetraethyl orthosilicate solution and ammonia water to the ethanol solution of cetyltrimethylammonium bromide for precipitation reaction. During the precipitation process, control the pH value at about 7.0. After precipitation, age for 1 hour, filter, wash, and dry at 110 °C to obtain the precursor a of the catalyst active component;

[0105] (3) Dissolve 3.615 g of NaOH in 1 L of deionized water, then add 82.58 g of sodium aluminate and stir evenly; dissolve 3.615 g of NaOH in 1 L of deionized water, then add 154.8 g of sodium metasilicate and stir evenly; quickly mix the solution of sodium aluminate and NaOH with the solution of sodium metasilicate and NaOH, add 560 g of the precursor a of the catalyst active component obtained in step (2), stir until a thick gel is formed, place it in a hydrothermal reaction kettle, crystallize at 99 ± 1 °C for 4 hours, filter, wash, dry at 110 °C, and calcine at 500 °C for 12 hours to obtain product b;

[0106] (4) Take 500 g of product b obtained in step (3), 35 g of polyethylene glycol, and 9 g of 40% HNO 3 Mix and knead, extrude into strips, dry, calcine at 600 °C for 4 hours, and cool to obtain a cylindrical 4A zeolite - SiO 2 composite catalyst.

[0107] Example 10

[0108] A preparation method of a catalyst for the reaction of caprolactam and ammonia to prepare 6 - aminocapronitrile, comprising the following steps:

[0109] (1) Add 208 g of tetraethyl orthosilicate to 3 L of 75% ethanol aqueous solution and stir evenly; dissolve 500 g of 25% ammonia water in 0.5 L of water; dissolve 2 g of cetyltrimethylammonium bromide in 20 mL of ethanol;

[0110] (2) At 50 °C, slowly add the above tetraethyl orthosilicate solution and ammonia water to the ethanol solution of cetyltrimethylammonium bromide for precipitation reaction. During the precipitation process, control the pH value at about 7.0. After precipitation, age for 1 hour, filter, wash, and dry at 110 °C to obtain the precursor a of the catalyst active component;

[0111] (3) Dissolve 3.615 g of NaOH in 1000 mL of deionized water, then add 82.58 g of sodium aluminate and stir evenly; dissolve 3.615 g of NaOH in 1000 mL of deionized water, then add 154.8 g of sodium metasilicate and stir evenly; quickly mix the solution of sodium aluminate and NaOH with the solution of sodium metasilicate and NaOH, add 560 g of the catalyst active component precursor a obtained in step (2), stir until a thick gel is formed, place it in a hydrothermal reaction kettle and crystallize at 99 ± 1 °C for 4 hours, filter, wash, dry at 110 °C, and calcine at 500 °C for 12 hours to obtain product b;

[0112] (4) Prepare a CaCl solution with a concentration of 0.6 mol / L and perform ion exchange with the product obtained in step (3): at a temperature of 80 °C, exchange for 2 hours, then filter, wash, and dry at 110 °C to obtain product c; 2 Solution and the product obtained in step (3) are subjected to ion exchange: at a temperature of 80 °C, exchange for 2 hours, then filter, wash, and dry at 110 °C to obtain product c;

[0113] (5) Take 500 g of product c obtained in step (4), 40 g of polyethylene glycol, and 12 g of 40% HNO 3 Mix and knead, extrude into strips, dry, calcine at 600 °C for 4 hours, and cool to obtain a cylindrical 5A molecular sieve - SiO 2 Composite catalyst.

[0114] Example 11

[0115] A preparation method of a catalyst for the reaction of caprolactam and ammonia to prepare 6 - aminocapronitrile, comprising the following steps:

[0116] (1) Add 256 g of Mg(NO 3 ) 2 ·6H 2 O to 2 L of water and stir until a clear solution is formed; dissolve 106 g of Na 2 CO 3 in 1 L of water; dissolve 2 g of tetrabutylammonium hydroxide in 20 mL of ethanol;

[0117] (2) At 50 °C, slowly add the above - mentioned Mg(NO 3 ) 2 solution and Na 2 CO 3 solution drop - by - drop into the ethanol solution of tetrabutylammonium bromide for precipitation reaction. During the precipitation process, the pH value is controlled at about 7.0. After precipitation, continue to stir for 1 hour, let stand, age at room temperature for 12 hours, filter, wash, and dry at 110 °C to obtain the catalyst active component precursor a;

[0118] (3) Dissolve 3.615 g of NaOH in 1 L of deionized water, then add 82.58 g of sodium aluminate and stir evenly; dissolve 3.615 g of NaOH in 1 L of deionized water, then add 154.8 g of sodium metasilicate and stir evenly; quickly mix the sodium aluminate and NaOH solution with the sodium metasilicate and NaOH solution, add 560 g of the catalyst active component precursor a described in step (2), stir until a thick gel is formed, place it in a hydrothermal reaction kettle and crystallize at 99 ± 1 °C for 4 hours, filter, wash, dry at 110 °C, and calcine at 500 °C for 4 hours to obtain product b;

[0119] (4) Prepare a 0.6 mol / L KCl solution and perform ion exchange with product b obtained in step (3): at a temperature of 80 °C, exchange for 2 hours, then filter, wash, and dry at 110 °C to obtain product c;

[0120] (5) Take 500 g of product c obtained in step (4), 60 g of polyethylene glycol, and 10 g of 40% HNO 3 Mix them, knead, extrude into strips, dry, calcine at 550 °C for 8 hours, and cool to obtain a cylindrical 3A molecular sieve - MgO composite catalyst.

[0121] Example 12

[0122] A preparation method of a catalyst for the reaction of caprolactam with ammonia to prepare 6 - aminocapronitrile, adopting the following method steps:

[0123] (1) Add 256 g of Mg(NO 3 ) 2 ·6H 2 O to 2 L of water and stir until a clear solution is formed; dissolve 106 g of Na 2 CO 3 in 1 L of water; dissolve 2 g of cetyltrimethylammonium chloride in 20 mL of ethanol;

[0124] (2) At 50 °C, slowly add the above - mentioned Mg(NO 3 ) 2 solution and Na 2 CO 3 solution drop - by - drop into the ethanol solution of cetyltrimethylammonium chloride for precipitation reaction. During the precipitation process, control the pH value at about 7.5. After the precipitation is completed, continue to stir for 1 hour, let it stand, age at room temperature for 12 hours, filter with suction, wash, and dry at 110 °C to obtain the catalyst active component precursor a;

[0125] (3) Dissolve 3.615 g of NaOH in 1000 mL of deionized water, then add 82.58 g of sodium aluminate and stir evenly; dissolve 3.615 g of NaOH in 1000 mL of deionized water, then add 154.8 g of sodium metasilicate and stir evenly; quickly mix the solution of sodium aluminate and NaOH with the solution of sodium metasilicate and NaOH, add 560 g of the catalyst active component precursor a obtained in step (2), stir until a thick gel is formed, place it in a hydrothermal reaction kettle and crystallize at 99 ± 1 °C for 4 hours, filter, wash, dry at 110 °C, and calcine at 500 °C for 4 hours to obtain product b;

[0126] (4) Mix 500 g of product b obtained in step (3), 30 g of polyethylene glycol pore-forming agent, and 10 g of 30% HNO 3 After mixing, knead, extrude into strips, dry at 110 °C for 24 hours, calcine at 550 °C for 8 hours, and cool to obtain a cylindrical 4A molecular sieve-MgO composite catalyst for the ammoniation of caprolactam to prepare 6-aminocapronitrile.

[0127] Example 13

[0128] A preparation method of a catalyst for the reaction of caprolactam with ammonia to prepare 6-aminocapronitrile, comprising the following steps:

[0129] (1) Add 375 g of Al(NO 3 ) 3 ·9H 2 O to 2 L of water and stir until a clear solution is formed; dissolve 40 g of NaOH in 1 L of water; dissolve 2 g of cetyltrimethylammonium chloride in 20 mL of ethanol;

[0130] (2) At 50 °C, slowly drop the above-mentioned Al(NO 3 ) 3 solution and NaOH solution into the ethanol solution of cetyltrimethylammonium chloride for precipitation reaction. During the precipitation process, the pH value is controlled at about 7.0. After the precipitation is completed, continue to stir for 1 hour, let it stand, age at room temperature for 12 hours, filter, wash, and dry at 110 °C to obtain the catalyst active component precursor a;

[0131] (3) Dissolve 3.615 g of NaOH in 1 L of deionized water, then add 82.58 g of sodium aluminate and stir evenly; dissolve 3.615 g of NaOH in 1 L of deionized water, then add 154.8 g of sodium metasilicate and stir evenly; quickly mix the solution of sodium aluminate and NaOH with the solution of sodium metasilicate and NaOH, add 560 g of the catalyst active component precursor a obtained in step (2), stir until a thick gel is formed, place it in a hydrothermal reaction kettle and crystallize at 99 ± 1 °C for 4 hours, filter, wash, dry at 110 °C, and calcine at 550 °C for 12 hours to obtain product b;

[0132] (4) Exchange the KCl solution with a concentration of 0.7 mol / L with the product b obtained in step (3): at a temperature of 80 °C, exchange for 2 hours, then filter, wash, and dry at 110 °C to obtain product c;

[0133] (5) Mix 500 g of the product c obtained in step (3), 30 g of polyethylene glycol pore-forming agent, and 20 g of 30% HNO 3 After mixing, knead, extrude into strips, dry at 110 °C for 24 hours, calcine at 500 °C for 8 hours, and cool to obtain a cylindrical 3A molecular sieve - Al 2 O 3 Composite catalyst.

[0134] Example 14

[0135] A preparation method of a catalyst for the reaction of caprolactam with ammonia to prepare 6 - aminocapronitrile, comprising the following steps:

[0136] (1) Add 375 g of Al(NO 3 ) 3 ·9H 2 O to 2 L of water and stir until a clear solution is formed; dissolve 106 g of Na 2 CO 3 in 1 L of water; dissolve 2 g of cetyltrimethylammonium bromide in 20 mL of ethanol;

[0137] (2) At 50 °C, slowly add the above Al(NO 3 ) 3 solution and the Na 2 CO 3 solution dropwise into the ethanol solution of cetyltrimethylammonium bromide for precipitation reaction. During the precipitation process, control the pH value at about 7.0. After precipitation, continue to stir for 1 hour, let stand, age at room temperature for 12 hours, filter, wash, and dry at 110 °C to obtain the precursor a of the catalyst active component;

[0138] (3) Dissolve 3.615 g of NaOH in 1000 mL of deionized water, then add 82.58 g of sodium aluminate and stir evenly; dissolve 3.615 g of NaOH in 1000 mL of deionized water, then add 154.8 g of sodium metasilicate and stir evenly; quickly mix the solution of sodium aluminate and NaOH with the solution of sodium metasilicate and NaOH, add 560 g of the precursor a of the catalyst active component obtained in step (2), stir until a thick gel is formed, place it in a hydrothermal reaction kettle, and crystallize at 99 ± 1 °C for 4 hours, filter, wash, dry at 110 °C, and calcine at 550 °C for 12 hours to obtain product b;

[0139] (4) Mix 500 g of the product b obtained in step (3), 60 g of polyacrylamide pore-forming agent, and 15 g of 40% HNO 3 After mixing, knead, extrude, dry at 110 °C for 24 hours, calcine at 550 °C for 4 hours, and after cooling, obtain a cylindrical 4A molecular sieve - Al 2 O 3 Composite catalyst for the ammoniation of caprolactam to prepare 6-aminocapronitrile.

[0140] Example 15

[0141] A preparation method of a catalyst for the reaction of caprolactam with ammonia to prepare 6-aminocapronitrile, comprising the following steps:

[0142] (1) Add 189 g of TiCl 4 to 2 L of water and stir until a clear solution is formed; dissolve 40 g of NaOH in 1 L of water; dissolve 2 g of cetyltrimethylammonium chloride in 20 mL of ethanol;

[0143] (2) At 50 °C, slowly drop the above TiCl 4 solution and NaOH solution into the ethanol solution of cetyltrimethylammonium chloride for precipitation reaction. During the precipitation process, the pH value is controlled at about 7.0. After precipitation, continue to stir for 1 hour, let stand, age at room temperature for 12 hours, filter, wash, and dry at 110 °C to obtain the precursor a of the catalyst active component;

[0144] (3) Dissolve 3.615 g of NaOH in 1 L of deionized water, then add 82.58 g of sodium aluminate and stir evenly; dissolve 3.615 g of NaOH in 1 L of deionized water, then add 154.8 g of sodium metasilicate and stir evenly; quickly mix the solution of sodium aluminate and NaOH and the solution of sodium metasilicate and NaOH, add 560 g of the precursor a of the catalyst active component obtained in step (2), stir until a thick gel is formed, place it in a hydrothermal reaction kettle, and crystallize at 99 ± 1 °C for 4 hours, filter, wash, dry at 110 °C, and calcine at 550 °C for 12 hours to obtain product b;

[0145] (4) Mix 500 g of the product b obtained in step (3), 50 g of polyethylene glycol pore-forming agent, and 30 g of 30% HNO 3 After mixing, knead, extrude, dry at 110 °C for 24 hours, calcine at 550 °C for 4 hours, and after cooling, obtain a cylindrical 4A molecular sieve - TiO 2 Composite catalyst for the ammoniation of caprolactam to prepare 6-aminocapronitrile.

[0146] Example 16

[0147] A preparation method of a catalyst for the reaction of caprolactam with ammonia to prepare 6-aminocapronitrile, comprising the following steps:

[0148] (1) Add 189 g of TiCl 4 to 2 L of water and stir until a clear solution is formed; dissolve 40 g of NaOH in 1 L of water; dissolve 2 g of cetyltrimethylammonium chloride in 20 mL of ethanol;

[0149] (2) At 50 °C, slowly add the above TiCl 4 solution and NaOH solution dropwise to the ethanol solution of cetyltrimethylammonium chloride for precipitation reaction. During the precipitation process, control the pH value at about 7.0. After precipitation, continue to stir for 1 hour, let stand, age at room temperature for 12 hours, filter, wash, and dry at 110 °C to obtain the precursor a of the catalyst active component;

[0150] (3) Dissolve 3.615 g of NaOH in 1 L of deionized water, then add 82.58 g of sodium aluminate and stir evenly; dissolve 3.615 g of NaOH in 1 L of deionized water, then add 154.8 g of sodium metasilicate and stir evenly; quickly mix the solution of sodium aluminate and NaOH and the solution of sodium metasilicate and NaOH, add 560 g of the precursor a of the catalyst active component obtained in step (2), stir until a thick gel is formed, place it in a hydrothermal reaction kettle, crystallize at 99 ± 1 °C for 4 hours, filter, wash, dry at 110 °C, and calcine at 550 °C for 12 hours to obtain product b;

[0151] (4) Prepare a CaCl solution with a concentration of 0.8 mol / L and perform ion exchange with product b obtained in step (3): at a temperature of 80 °C, exchange for 2 hours, then filter, wash, and dry at 110 °C to obtain product c; 2

[0152] (5) Mix 500 g of product c obtained in step (4), 50 g of polyethylene glycol pore-forming agent, and 30 g of 30% HNO 3 and knead, extrude, dry at 110 °C for 24 hours, calcine at 550 °C for 4 hours, and cool to obtain a cylindrical 5A molecular sieve - TiO 2 composite catalyst.

[0153] Comparative Example 1

[0154] The preparation method of Comparative Catalyst 1 is as follows:

[0155] (1) Add 429 g of Zr(NO 3 ) 4 ·5H 2 O to 3 L of water and stir until a clear solution is formed; dissolve 318 g of Na 2 CO 3 in 1 L of water; dissolve 4 g of cetyltrimethylammonium bromide in 20 mL of ethanol;​

[0156] (2) At 60 °C, the above Zr(NO 3 ) 3 solution and Na 2 CO 3 solution were slowly added dropwise to an ethanol solution of cetyltrimethylammonium bromide for precipitation reaction. During the precipitation process, the pH value was controlled at about 7.0. After precipitation, stirring was continued for 1 hour, then left standing, aged at room temperature for 12 hours, filtered, washed, and dried at 110 °C to obtain the precursor of the catalyst active component;

[0157] (3) 500 g of the above precursor of the active component, 40 g of polyacrylamide pore-forming agent, and 20 g of 20% HNO 3 were mixed and kneaded, extruded into strips, dried at 110 °C for 24 hours, calcined at 450 °C for 4 hours, and after cooling, a cylindrical ZrO 2 catalyst with a diameter of 3 mm was obtained.

[0158] Comparative Example 2

[0159] The preparation method of Comparative Catalyst 2 is as follows:

[0160] Preparation of 3A molecular sieve: 3.615 g of NaOH was dissolved in 1 L of deionized water, and then 82.58 g of sodium aluminate was added and stirred evenly; 3.615 g of NaOH was dissolved in 1 L of deionized water, and then 154.8 g of sodium metasilicate was added and stirred evenly; the solution of sodium aluminate and NaOH, and the solution of sodium metasilicate and NaOH were quickly mixed and stirred until a thick gel was formed. After being placed in a hydrothermal reaction kettle, it was crystallized at 99 ± 1 °C for 4 h, filtered, washed, and dried at 110 °C to obtain product a; a KC1 solution with a concentration of 0.6 mol / L was prepared for ion exchange with product a: at a temperature of 80 °C, the exchange was carried out for 2 hours, then filtered, washed, dried at 110 °C, and calcined at 500 °C for 12 hours to obtain 3A molecular sieve.

[0161] (1) 429 g of Zr(NO 3 ) 4 ·5H 2 O was added to 3 L of water and stirred until a clear solution was formed; 318 g of Na 2 CO 3 was dissolved in 1 L of water; 4 g of cetyltrimethylammonium bromide was dissolved in 20 mL of ethanol;

[0162] (2) At 60 °C, the Zr(NO 3 ) 3 solution and Na 2 CO 3The solution was slowly added dropwise to an ethanol solution of cetyltrimethylammonium bromide for precipitation reaction. During the precipitation process, the pH value was controlled at about 7.0. After precipitation, stirring was continued for 1 hour, followed by standing, aging at room temperature for 12 hours, suction filtration, washing, and drying at 110 °C to obtain the precursor of the catalyst active component;

[0163] (3) Mix 50 g of 3A molecular sieve, 500 g of the above-mentioned precursor of the active component, 40 g of polyacrylamide pore-forming agent, and 20 g of 20% HNO 3 After mixing, knead, extrude into strips, dry at 110 °C for 24 hours, calcine at 550 °C for 4 hours, and cool to obtain a cylindrical 3A molecular sieve-ZrO 2 composite catalyst with a diameter of 3 mm.

[0164] Comparative Example 3

[0165] The preparation method of the comparative catalyst 3 is as follows:

[0166] Preparation of 3A molecular sieve: Dissolve 3.615 g of NaOH in 1 L of deionized water, then add 82.58 g of sodium aluminate and stir evenly; dissolve 3.615 g of NaOH in 1 L of deionized water, then add 154.8 g of sodium metasilicate and stir evenly; quickly mix the solution of sodium aluminate and NaOH with the solution of sodium metasilicate and NaOH, stir until a thick gel is formed, place it in a hydrothermal reaction kettle and crystallize at 99 ± 1 °C for 4 hours, filter, wash, and dry at 110 °C to obtain product a; prepare a 0.6 mol / L KCl solution for ion exchange with product a: at a temperature of 80 °C, exchange for 2 hours, then filter, wash, dry at 110 °C, and calcine at 500 °C for 12 hours to obtain 3A molecular sieve.

[0167] (1) Add 429 g of Zr(NO 3 ) 4 ·5H 2 O to 3 L of water and stir until a clear solution is formed; dissolve 318 g of Na 2 CO 3 in 1 L of water; dissolve 4 g of cetyltrimethylammonium bromide in 20 mL of ethanol;

[0168] (2) At 60 °C, slowly add dropwise the Zr(NO 3 ) 3 solution and the Na 2 CO 3 solution to the ethanol solution of cetyltrimethylammonium bromide for precipitation reaction. During the precipitation process, the pH value was controlled at about 7.0. After precipitation, stirring was continued for 1 hour, followed by standing, aging at room temperature for 12 hours, suction filtration, washing, and drying at 110 °C to obtain the precursor of the catalyst active component;

[0169] (3) Grind 50 g of 3A molecular sieve, 500 g of the above-mentioned active component precursor, and 50 g of polyacrylamide pore-forming agent with a planetary ball mill for 12 hours, then add 20 g of 20% HNO 3 Mix and knead, extrude into strips, dry at 110 °C for 24 hours, calcine at 450 °C for 4 hours, and cool to obtain a cylindrical 3A molecular sieve-ZrO with a diameter of 3 mm 2 composite catalyst.

[0170] Comparative Example 4

[0171] The preparation method of Comparative Catalyst 4 is as follows:

[0172] (1) Add 429 g of Zr(NO 3 ) 4 ·5H 2 O to 3 L of water and stir until a clear solution is formed; dissolve 318 g of Na 2 CO 3 in 1 L of water; dissolve 4 g of cetyltrimethylammonium bromide in 20 mL of ethanol;

[0173] (2) At 60 °C, slowly add the above Zr(NO 3 ) 4 solution and Na 2 CO 3 solution dropwise to the ethanol solution of cetyltrimethylammonium bromide for precipitation reaction. During the precipitation process, control the pH value at about 7.0. After precipitation, continue to stir for 1 hour, let stand, age at room temperature for 12 hours, filter, wash, and dry at 110 °C to obtain the active component precursor a of the catalyst;

[0174] (3) Dissolve 3.615 g of NaOH in 1 L of deionized water, then add 82.58 g of sodium aluminate and stir evenly; dissolve 3.615 g of NaOH in 1 L of deionized water, then add 154.8 g of sodium metasilicate and stir evenly; quickly mix the sodium aluminate and NaOH solution with the sodium metasilicate and NaOH solution, add 560 g of the active component precursor a of the catalyst described in step (2), stir until a thick gel is formed, place it in a hydrothermal reaction kettle, and crystallize at 99 ± 1 °C for 4 hours, filter, wash, dry at 110 °C, and calcine at 400 °C for 6 hours to obtain product b;

[0175] (4) Prepare a KCl solution with a concentration of 0.6 mol / L and perform ion exchange with product b obtained in step (3): at a temperature of 80 °C, exchange for 2 hours, then filter, wash, and dry at 110 °C to obtain product c;

[0176] (5) Take 500 g of product c obtained in step (4), add 40 g of polyacrylamide, and then add 10 g of 68% HNO3 After mixing, kneading, extrusion, drying, calcining at 400 °C for 12 hours, and cooling, a cylindrical 3A molecular sieve-ZrO 2 composite catalyst is obtained.

[0177] Comparative Example 5

[0178] The preparation method of the comparative catalyst 5 is as follows:

[0179] (1) Add 429 g of Zr(NO 3 ) 4 ·5H 2 O to 3 L of water and stir until a clear solution is formed; dissolve 318 g of Na 2 CO 3 in 1 L of water; dissolve 4 g of cetyltrimethylammonium bromide in 20 mL of ethanol;

[0180] (2) At 60 °C, slowly add the above Zr(NO 3 ) 4 solution and Na 2 CO 3 solution dropwise to the ethanol solution of cetyltrimethylammonium bromide for precipitation reaction. During the precipitation process, the pH value is controlled at about 7.0. After the precipitation is completed, continue to stir for 1 hour, let stand, age at room temperature for 12 hours, filter, wash, and dry at 110 °C to obtain the precursor a of the catalyst active component;

[0181] (3) Dissolve 3.615 g of NaOH in 1 L of deionized water, then add 82.58 g of sodium aluminate and stir evenly; dissolve 3.615 g of NaOH in 1 L of deionized water, then add 154.8 g of sodium metasilicate and stir evenly; quickly mix the sodium aluminate and NaOH solution with the sodium metasilicate and NaOH solution, add 560 g of the precursor a of the catalyst active component described in step (2), stir until a thick gel is formed, place it in a hydrothermal reaction kettle, and crystallize at 99 ± 1 °C for 4 hours, filter, wash, dry at 110 °C, and calcine at 750 °C for 6 hours to obtain product b;

[0182] (4) Prepare a CaCl solution with a concentration of 0.6 mol / L and perform ion exchange with product b obtained in step (3): at a temperature of 80 °C, exchange for 2 hours, then filter, wash, and dry at 110 °C to obtain product c; 2 solution and product b obtained in step (3) for ion exchange: at a temperature of 80 °C, exchange for 2 hours, then filter, wash, and dry at 110 °C to obtain product c;

[0183] (5) Take 500 g of product c obtained in step (4), add 40 g of polyacrylamide, and then add 10 g of 68% HNO 3 After mixing, kneading, extrusion, drying, calcining at 550 °C for 6 hours, and cooling, a cylindrical 5A molecular sieve-ZrO 2 composite catalyst is obtained.

[0184] Comparative Example 6

[0185] The preparation method of the comparative catalyst 6 is as follows:

[0186] (1) Add 429 g of Zr(NO 3 ) 4 ·5H 2 O to 3 L of water and stir until a clear solution is formed; dissolve 318 g of Na 2 CO 3 in 1 L of water; dissolve 4 g of cetyltrimethylammonium bromide in 20 mL of ethanol;

[0187] (2) At 60 °C, slowly add the above Zr(NO 3 ) 4 solution and the Na 2 CO 3 solution dropwise into the ethanol solution of cetyltrimethylammonium bromide for precipitation reaction. During the precipitation process, control the pH value at about 7.0. After the precipitation is completed, continue to stir for 1 hour, let it stand, age at room temperature for 12 hours, filter, wash, and dry at 110 °C to obtain the precursor a of the catalyst active component;

[0188] (3) Dissolve 3.615 g of NaOH in 1 L of deionized water, then add 82.58 g of sodium aluminate and stir evenly; dissolve 3.615 g of NaOH in 1 L of deionized water, then add 154.8 g of sodium metasilicate and stir evenly; quickly mix the sodium aluminate and NaOH solution with the sodium metasilicate and NaOH solution, add 560 g of the precursor a of the catalyst active component described in step (2), stir until a thick gel is formed, place it in a hydrothermal reaction kettle, crystallize at 99 ± 1 °C for 4 hours, filter, wash, dry at 110 °C, and calcine at 550 °C for 6 hours to obtain product b;

[0189] (4) Prepare a CaCl 2 solution with a concentration of 0.6 mol / L and perform ion exchange with product b obtained in step (3): at a temperature of 80 °C, exchange for 2 hours, then filter, wash, and dry at 110 °C to obtain product c;

[0190] (5) Take 500 g of product c obtained in step (4), add 40 g of polyacrylamide, then add 10 g of 68% HNO 3 Mix and knead, extrude into strips, dry, calcine at 800 °C for 6 hours, and cool to obtain a cylindrical 5A zeolite-ZrO 2 composite catalyst.

[0191] Comparative Example 7

[0192] The preparation method of the comparative catalyst 7 is as follows:

[0193] (1) Add 429 g of Zr(NO 3 ) 4 ·5H 2 O to 3 L of water and stir until a clear solution is formed; dissolve 318 g of Na 2 CO 3 in 1 L of water; dissolve 4 g of cetyltrimethylammonium bromide in 20 mL of ethanol;

[0194] (2) At 60 °C, slowly add the above Zr(NO 3 ) 4 solution and Na 2 CO 3 solution dropwise to the ethanol solution of cetyltrimethylammonium bromide for precipitation reaction. During the precipitation process, control the pH value at about 7.0. After the precipitation is completed, continue to stir for 1 hour, let it stand, age at room temperature for 12 hours, filter, wash, and dry at 110 °C to obtain the precursor a of the catalyst active component;

[0195] (3) Dissolve 3.615 g of NaOH in 1 L of deionized water, then add 82.58 g of sodium aluminate and stir evenly; dissolve 3.615 g of NaOH in 1 L of deionized water, then add 154.8 g of sodium metasilicate and stir evenly; quickly mix the solution of sodium aluminate and NaOH with the solution of sodium metasilicate and NaOH, add 560 g of the precursor a of the catalyst active component described in step (2), stir until a thick gel is formed, place it in a hydrothermal reaction kettle, crystallize at 99 ± 1 °C for 4 hours, filter, wash, dry at 110 °C, and calcine at 550 °C for 6 hours to obtain product b;

[0196] (4) Prepare a CaCl 2 solution with a concentration of 0.6 mol / L and perform ion exchange with product b obtained in step (3): at a temperature of 80 °C, exchange for 2 hours, then filter, wash, and dry at 110 °C to obtain product c;

[0197] (5) Take 500 g of product c obtained in step (4), add 40 g of polyacrylamide, then add 10 g of 68% HNO 3 Mix and knead, extrude into strips, dry, calcine at 350 °C for 6 hours, and cool to obtain a cylindrical 5A zeolite-ZrO 2 composite catalyst.

[0198] Test Examples

[0199] The catalysts prepared in the above Examples 1 to 13 and Comparative Examples 1 - 7 were subjected to the ammoxidation reaction of caprolactam in a continuous flow fixed-bed stainless steel reactor. The reactor was 2 meters long and had an inner diameter of 25 mm. It was heated by molten salt, and the catalyst loading was 1000 mL. The preheated caprolactam was mixed with hot ammonia gas at a rate of 200 - 5000 g / h and then entered the catalyst bed for the ammoxidation reaction. The molar ratio of ammonia gas / caprolactam was 8 - 50. The reaction solution was cooled and then entered the gas-liquid separation tank, where all the liquid reaction products were collected, weighed, and analyzed for composition. The conversion rate of caprolactam and the selectivity for the formation of 6-aminocapronitrile were calculated, and the results are listed in Table 1 respectively.

[0200] Under the conditions of Example 1 in Table 1, a 1000-hour stability experiment was carried out on the catalyst prepared in Example 1, and the results are shown in Figure 2 , indicating its good stability.

[0201] Table 1 Summary of Catalyst Activity Data

[0202]

[0203]

[0204] The catalysts in Examples 1 - 16 are all similar Figure 1 with the active component as the core and the molecular sieve as the outer layer in structure. There is a strong interaction between the active component particles and the molecular sieve crystals, and they are closely combined. Water, one of the reaction products, can be quickly adsorbed and desorbed by the surface molecular sieve, thereby driving the reaction forward. The main differences between the catalysts in different examples are the types and contents of the active component and the molecular sieve, as well as the difference in the calcination temperature.

[0205] In Comparative Example 1, no molecular sieve was added. In Comparative Example 2, the catalyst was prepared by simply mixing the active component and the molecular sieve, and the distance between the active component and the molecular sieve microcrystals was relatively far, so water could not be quickly adsorbed from the active surface to the molecular sieve surface in a timely manner. In Comparative Example 3, the catalyst was prepared by ball-milling and dispersing the active component and the molecular sieve, which shortened the distance between the two. The molecular sieve played a certain role in quickly adsorbing / desorbing water, but the effect was not good. Comparing the data of these three comparative examples and Example 1, it can be seen that adding a molecular sieve helps the forward reaction of caprolactam ammoxidation to produce 6-aminocapronitrile, and can improve the conversion rate of caprolactam and the selectivity for 6-aminocapronitrile (Comparative Example 1, Example 1). However, this method cannot be a simple mixing (Comparative Example 2, Comparative Example 3, Example 1), and only the method of in-situ crystallization of the molecular sieve on the surface of the active component, that is, the structural form of constructing a molecular sieve shell layer on the active component core, is effective.

[0206] In Comparative Examples 4-7, the catalyst was prepared by in-situ crystallization of zeolite on the surface of the active component, and the catalyst was similar to a core-shell structure. The main differences among the comparative examples were the type of zeolite, the calcination temperature after zeolite crystallization, and the calcination temperature after extrusion molding. Both the calcination temperature after zeolite crystallization and the calcination temperature after pore formation had an impact on the catalytic performance of the zeolite: after zeolite crystallization, at a relatively low calcination temperature, the pore diameter of the accumulated pores formed on the surface of the zeolite was too small, which was not conducive to the diffusion of caprolactam to the surface of the active component and also not conducive to the desorption of 6-aminocapronitrile from the surface of the active component. Therefore, the conversion rate of caprolactam on the catalyst was relatively low (Comparative Example 4); at a relatively high calcination temperature, the grains of the composite catalyst became larger and the number of active sites decreased, which would also cause a decrease in the conversion rate of caprolactam on the catalyst (Comparative Example 5). After the pore-forming agent was added, too low a calcination temperature would cause incomplete decomposition of the pore-forming agent and could not play a pore-forming role, thus being not conducive to the diffusion of caprolactam / 6-aminocapronitrile and resulting in low catalytic activity (Comparative Example 7); too high a calcination temperature after the pore-forming agent was added would also cause the catalyst grains to become larger and the number of active sites to decrease, thereby resulting in low catalytic activity of the catalyst (Comparative Example 6). Therefore, too low / high calcination temperature was not conducive to the preparation of a catalyst with high catalytic activity.

Claims

1. A catalyst for the reaction of caprolactam with ammonia to prepare 6 - aminocapronitrile, which has a core of active components, and a shell is in - situ crystallized on the surface of the core by a dehydration aid, and has a pore structure in the shell or the core - shell; the active components are selected from one or more of zirconium oxide, silicon dioxide, magnesium oxide, aluminum oxide, titanium oxide, boron oxide, zinc oxide, and lanthanum oxide; the dehydration aid is a weakly acidic molecular sieve, and the weakly acidic molecular sieve is selected from one or more of 3A, 4A, and 5A; by mass percentage, the active components account for 10 - 99% of the catalyst.

2. The catalyst according to claim 1, characterized in that, the weakly acidic molecular sieve is 3A molecular sieve; and / or, The active component is selected from ZrO 2 , SiO 2 , MgO, Al 2 O 3 , TiO 2 ; and / or, by mass percentage, the active components account for 40 - 90% of the catalyst; and / or, the surface pore diameter of the catalyst is 5 - 30 nm.

3. The catalyst according to claim 1, characterized in that, by mass percentage, the active components account for 50 - 85% of the catalyst 4. A preparation method of the catalyst for the reaction of caprolactam with ammonia to prepare 6 - aminocapronitrile according to any one of claims 1 - 3, characterized in that, the preparation method adopts the in - situ crystallization method, and comprises the following steps: (1) At 50 - 60 °C, a soluble compound solution A selected from one or more of active elements zirconium, silicon, boron, magnesium, zinc, lanthanum, titanium, and aluminum and an aqueous precipitant solution B are slowly added dropwise to an ethanol solution C of a dispersant for precipitation reaction. During the precipitation process, the pH value is controlled at 4 - 10. After the precipitation ends, stirring continues for 0.5 - 2 hours, standing, aging at room temperature for 8 - 24 hours, or crystallizing at 110 - 250 °C for 1 - 48 hours, filtering, washing, and drying to obtain a catalyst active component precursor a; wherein, the dosage ratio of the active element: precipitant: dispersant is 1 mol: 0.5 - 10 mol: 1 - 6 g, and the volume ratio of the solution A: solution B: solution C is 0.5 - 5 L: 0.1 - 2 L: 10 - 30 mL; (2) An aqueous solution D of sodium aluminate and sodium hydroxide and an aqueous solution E of sodium metasilicate and sodium hydroxide are rapidly mixed, the catalyst active component precursor a is added, stirred until a thick gel is formed, crystallized, filtered, washed, dried, and calcined at 450 - 700 °C for 1 - 24 hours to obtain product b; (3) After the product b is subjected to ion exchange with an aqueous solution of KCl or CaCl 2 , it is filtered, washed, and dried to obtain the product c; (4) Take the product b or product c, mix it with a pore-forming agent and an aqueous solution of 5-68 wt% HNO 3 and knead, extrude, dry, and calcine at 400-750 °C for 1-24 hours, and then cool to obtain the catalyst; wherein, the dosage ratio of the product b or product c: pore-forming agent: aqueous solution of 5-68 wt% HNO 3 is 200-1000 g: 10-300 g: 2-300 g.

5. The preparation method according to claim 4, characterized in that, in step (1): The soluble compound of the active element is selected from Zr(NO 3 ) 4 , tetraethyl orthosilicate, Mg(NO 3 ) 2 , Al(NO 3 ) 3 , TiCl 4 ; and / or, the solvent of the soluble compound solution A of the active element is water or an ethanol - aqueous solution; and / or, the precipitant is selected from one or more of sodium carbonate, sodium hydroxide, and ammonia; and / or, the dispersant is selected from one or more of dodecyl trimethyl ammonium bromide, dodecyl trimethyl ammonium chloride, cetyl trimethyl ammonium bromide, cetyl trimethyl ammonium chloride, octadecyl trimethyl ammonium bromide, octadecyl trimethyl ammonium chloride, tetramethyl ammonium hydroxide, and tetrabutyl ammonium bromide; and / or, The dosage ratio of the active element: precipitant: dispersant is: 1 mol: 1 - 7 mol: 1 - 6 g; the volume ratio of solution A: solution B: solution C is: 2 - 3 L: 0.5 - 1 L: 15 - 25 mL; and / or, During the precipitation process, the pH value is controlled at 6 - 8; and / or, After the precipitation is completed, the stirring time is 0.8 - 1.5 hours; and / or, The aging time at room temperature is 10 - 14 hours.

6. The preparation method according to claim 5, characterized in that, In step (1): The soluble compound of the active element is Zr(NO 3 ) 4 ; and / or, The dispersant is selected from cetyltrimethylammonium bromide, cetyltrimethylammonium chloride, tetramethylammonium hydroxide, and tetrabutylammonium bromide; and / or, During the precipitation process, the pH value is controlled at 7 - 7.5; and / or, After the precipitation is completed, the stirring time is 1 hour; and / or, The aging time at room temperature is 12 hours.

7. The preparation method according to claim 4, characterized in that, In step (2): The dosage ratio of the catalyst active component precursor a: sodium aluminate: sodium metasilicate is: 250 - 1200 g: 50 - 120 g: 80 - 200 g; and / or, The crystallization temperature is 60 - 140 °C, and the crystallization time is 1 - 48 hours.

8. The preparation method according to claim 7, characterized in that, In step (2): The dosage ratio of the catalyst active component precursor a: sodium aluminate: sodium metasilicate is: 400 - 600 g: 60 - 100 g: 120 - 180 g; and / or, The crystallization temperature is 90 - 110 °C, and the crystallization time is 2 - 8 hours.

9. The preparation method according to claim 4, characterized in that, In step (2): The calcination temperature is 450 - 650 °C, and the time is 6 - 12 hours.

10. The preparation method according to claim 4, characterized in that, In step (3): The concentration of the aqueous solution of the KCl or CaCl 2 is 0.6 to 0.8 mol / L; and / or, The ion exchange temperature is 40 - 90 °C, and / or, The ion exchange time is 0.1 - 2.5 hours.

11. The preparation method according to claim 10, characterized in that, In step (3): The ion exchange temperature is 70 - 90 °C, and / or, The ion exchange time is 1 - 2 hours.

12. The preparation method according to claim 10, characterized in that, In step (3): The ion exchange temperature is 80 °C, and / or, The ion exchange time is 2 hours.

13. The preparation method according to claim 4, characterized in that, In step (4), The pore-forming agent is selected from one or more of polyacrylamide, polyvinyl alcohol, polyethylene glycol, sesbania powder, carbon black, polyethylene oxide, and carboxymethyl cellulose; and / or, The concentration of the HNO 3 aqueous solution is 20 to 68 wt%; and / or, The product b or product c: Pore-forming agent: HNO 3 The dosage ratio of the aqueous solution is: 500 g: 30 - 60 g: 8 - 30 g; and / or, The calcination temperature is 450 - 600 °C, and the calcination time is 4 - 12 hours.

14. The preparation method according to claim 4, characterized in that, In steps (1) - (4), The drying temperature is 90 - 130 °C.

15. The preparation method according to claim 14, characterized in that, The drying temperature is 100 - 120 °C.

16. A method for preparing 6 - aminocapronitrile by the reaction of caprolactam with ammonia, which conducts the reaction of caprolactam with ammonia in the presence of the catalyst described in any one of claims 1 - 3.

17. According to the method described in claim 16, it is characterized in that the temperature of the reaction is 340 - 400 °C.

18. According to the method described in claim 17, it is characterized in that the temperature of the reaction is 340 - 380 °C.

19. According to the method described in claim 16, it is characterized in that the molar ratio of ammonia to caprolactam is 8 - 50.

20. According to the method described in claim 19, it is characterized in that the molar ratio of ammonia to caprolactam is 12 - 30.

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