Molecular sieve adsorbent applied to synthesis ammonia production and preparation method thereof

Abstract

The invention relates to the technical field of adsorbent synthesis, and discloses a molecular sieve adsorbent applied to synthesis ammonia production and a preparation method thereof. The preparation method comprises the following steps: reacting a silane coupling agent with an amine compound to prepare a silane precursor; ascorbic acid is used as a reducing agent, and composite modified liquid is formed in the copper salt solution; synthesizing a molecular sieve matrix and carrying out magnesium ion exchange modification; and finally, carrying out dipping treatment on the composite molecular sieve matrix and the modification liquid in an inert atmosphere, and carrying out heat treatment to obtain the adsorbent. The adsorbent has a highly ordered pore structure, can selectively adsorb impurities such as carbon dioxide, moisture and trace alcohols in synthetic ammonia feed gas, has the characteristics of large adsorption capacity, high selectivity, good thermal stability and excellent regeneration performance, and can effectively improve the production efficiency and product purity of synthetic ammonia.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of adsorbent synthesis, and particularly relates to a molecular sieve adsorbent applied to synthesis ammonia production and a preparation method thereof. BACKGROUND

[0002] The synthesis ammonia industry is the basis of nitrogen fertilizer production, energy storage and manufacturing of various chemical products, and a high-purity nitrogen-hydrogen mixed gas needs to be used in the production process. Raw gas often contains carbon dioxide, moisture and alcohol impurities, which not only causes the poisoning and deactivation of the synthesis ammonia catalyst, but also forms corrosion or blockage in the pipeline equipment, seriously affecting the production efficiency and product quality. Therefore, before the synthesis gas enters the synthesis tower, high-efficiency purification treatment must be carried out.

[0003] At present, the commonly used purification methods include low-temperature separation, solvent absorption and solid adsorption. Among them, the molecular sieve adsorbent is widely used in the gas separation and purification process due to its regular pore structure and selective adsorption characteristics. In the synthesis ammonia process, the molecular sieve is mainly used to remove CO, CO2 and H2O and other components in the raw gas, however, the traditional molecular sieve adsorbent has problems of limited adsorption capacity, low selectivity, poor thermal stability and insufficient regeneration performance. Especially in the high-temperature and high-pressure synthesis ammonia process environment, the ordinary molecular sieve is prone to have the phenomena of decreased adsorption efficiency and shortened service life, which limits its application in the field of efficient gas separation. Therefore, the present application provides a molecular sieve adsorbent applied to synthesis ammonia production and a preparation method thereof to solve the above-mentioned technical problems. SUMMARY

[0004] The purpose of the present application is to provide a molecular sieve adsorbent applied to synthesis ammonia production and a preparation method thereof, the adsorbent has a highly ordered pore structure, can selectively adsorb carbon dioxide, moisture and trace alcohol impurities in the raw gas for synthesis ammonia production, has the characteristics of large adsorption capacity, high selectivity, good thermal stability and excellent regeneration performance, and can effectively improve the synthesis ammonia production efficiency and product purity.

[0005] In the first aspect, the present application provides a preparation method of a molecular sieve adsorbent applied to synthesis ammonia production, which adopts the following technical scheme:

[0006] The preparation method of the molecular sieve adsorbent applied to synthesis ammonia production comprises the following steps:

[0007] S1, 3-aminopropyltriethoxysilane and ethylenediamine are dissolved in anhydrous ethanol, glacial acetic acid is added to adjust the pH to 6-7, and the reaction is carried out under nitrogen protection at 300-400 rpm, and then the silane precursor is obtained by vacuum concentration, and the silane precursor is sealed, filled with nitrogen and stored in the dark;

[0008] S2, dissolve copper acetate in mixed solvent, under stirring and nitrogen protection, add ascorbic acid to react, add silane precursor prepared in S1, continue to stir and react to obtain a composite modified solution, seal and store in the dark under nitrogen protection;

[0009] S3, take sodium silicate, sodium aluminate, sodium hydroxide and deionized water in turn into a polytetrafluoroethylene lined reaction kettle, stir and dissolve at room temperature at 350-400 rpm, seal the reaction kettle, heat and then keep constant temperature for crystallization, cool, filter and wash until neutral, filter cake is dried at 100-120℃ with air blowing for 4-6h, calcined at 500-550℃ for 1-2h, and grinded through a 200-300 mesh sieve to obtain a molecular sieve matrix;

[0010] S4, take the molecular sieve matrix and magnesium chloride together into deionized water, ion exchange at 200-300 rpm, filter, wash and dry to obtain a composite molecular sieve matrix;

[0011] S5, take the composite molecular sieve matrix into the composite modified solution prepared in S2, immerse at room temperature under nitrogen protection, transfer to a tube furnace after vacuum drying, heat treat under nitrogen atmosphere, cool, grind through a 180-300 mesh sieve to obtain a molecular sieve adsorbent.

[0012] Preferably, in step S1, 10-15 parts of 3-aminopropyltriethoxysilane, 5-8 parts of ethylenediamine, 50-55 parts of anhydrous ethanol and 0.5-0.8 parts of glacial acetic acid are used.

[0013] Preferably, in step S2, 5-7 parts of copper acetate, 25-35 parts of mixed solvent, 2-3 parts of ascorbic acid and 10-15 parts of silane precursor are used, and the mixed solvent is composed of 20-25 parts of anhydrous methanol and 5-10 parts of deionized water.

[0014] Preferably, in step S3, 6-8 parts of sodium silicate, 2-4 parts of sodium aluminate, 0.8-1.2 parts of sodium hydroxide and 40-45 parts of deionized water are used.

[0015] Preferably, in step S4, 8-12 parts of molecular sieve matrix, 1-3 parts of magnesium chloride and 70-80 parts of deionized water are used.

[0016] Preferably, in step S5, 8-12 parts of composite molecular sieve matrix and 40-45 parts of composite modified solution are used.

[0017] Preferably, the reaction in step S1 is carried out at 60-70℃, and the reaction time is 2-4h.

[0018] Preferably, the reaction after adding ascorbic acid in step S2 is carried out at 40-45℃ for 25-35min, and the reaction is continued for 1-2h after adding the silane precursor; the constant temperature crystallization in step S3 is carried out at 100-105℃ for 8-10h.

[0019] Preferably, the ion exchange in step S4 is carried out at 70-80℃ for 1-3h; the impregnation time in step S5 is 4-6h, and the temperature is raised to 350-420℃ at a rate of 2-4℃ / min during the heat treatment process, and the temperature is maintained at 350-420℃ for 2-3h.

[0020] In a second aspect, the present application also provides a molecular sieve adsorbent applied to synthetic ammonia production, which adopts the following technical scheme:

[0021] A molecular sieve adsorbent applied to synthetic ammonia production is prepared by the above preparation method.

[0022] The present application has the following beneficial effects:

[0023] The present application successfully prepares a composite molecular sieve adsorbent with highly ordered pore structure and rich active sites by reacting a silane coupling agent with an amine compound to prepare a silane precursor, using ascorbic acid as a reducing agent to form a composite modification liquid in a copper salt solution, synthesizing a molecular sieve matrix and modifying it by magnesium ion exchange, and finally impregnating the composite molecular sieve matrix with the modification liquid and heat treating it in an inert atmosphere. The adsorbent exhibits excellent comprehensive performance in the raw gas purification process of synthetic ammonia, has high adsorption capacity, which is provided by the ordered open pore structure and the uniformly distributed copper-magnesium active components, has excellent selective adsorption capacity, which is due to the specific combination of the amino groups on the surface with metal sites to carbon dioxide, water and alcohol molecules, and has good thermal stability and cyclic regeneration performance, so that it can maintain structural integrity and adsorption activity under harsh conditions of high temperature and high humidity, significantly prolongs the service life of the adsorbent, reduces the energy consumption of the synthetic ammonia process, and improves the purity of the ammonia product. DETAILED DESCRIPTION

[0024] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0025] The experimental methods in the following examples are all conventional methods, and the experimental materials used are all purchased from conventional biochemical reagent stores unless otherwise specified. The quantitative tests in the following examples are all set up with three repeated experiments, and the data are the average values of the three repeated experiments or the average values ± standard deviations.

[0026] Example 1

[0027] The present embodiment provides a preparation method of a molecular sieve adsorbent applied to synthetic ammonia production, comprising the following steps:

[0028] S1, 10 parts of 3-aminopropyltriethoxysilane and 5 parts of ethylenediamine were dissolved in 50 parts of anhydrous ethanol, 0.5 parts of glacial acetic acid was added to adjust the pH to 6.5, and the reaction was carried out at 60°C under nitrogen protection at a stirring speed of 300 rpm for 4 h. After the reaction was completed, the silane precursor was obtained by vacuum concentration, and was sealed and stored under nitrogen protection and away from light for standby use;

[0029] S2, 5 parts of copper acetate was dissolved in a mixed solvent composed of 20 parts of anhydrous methanol and 5 parts of deionized water, 2 parts of ascorbic acid was added under nitrogen protection and 350 rpm stirring, and the reaction was carried out at 40°C for 35 min. Then, 10 parts of the silane precursor was added for further reaction for 2 h to obtain a composite modification liquid, which was sealed and stored under nitrogen protection and away from light;

[0030] S3, 6 parts of sodium silicate, 2 parts of sodium metaaluminate and 0.8 parts of sodium hydroxide were dissolved in 40 parts of deionized water, and were fully dissolved at room temperature under 350 rpm stirring for 30 min. The mixed liquid was transferred into a polytetrafluoroethylene-lined reaction kettle, sealed, and crystallized at 100°C for 10 h. After cooling, it was suction filtered and washed with deionized water until the filtrate was neutral. The obtained solid was dried at 100°C under blast for 6 h, and then calcined at 500°C for 2 h. After being ground through a 200 mesh sieve, a molecular sieve matrix was obtained;

[0031] S4, 8 parts of the molecular sieve matrix and 1 part of magnesium chloride were added into 70 parts of deionized water, and ion exchange was carried out at 70°C under 200 rpm stirring for 3 h. After filtration and washing, it was dried at 100°C for 6 h to obtain a composite molecular sieve matrix;

[0032] S5, under nitrogen protection, 8 parts of the composite molecular sieve matrix was immersed in 40 parts of the composite modification liquid, and stirred at room temperature at 250 rpm for 6 h. After filtration, it was vacuum dried at 60°C for 4 h, and then heat treated at 2°C / min to 350°C in a nitrogen atmosphere for 3 h. After cooling, it was ground through a 180 mesh sieve to obtain a molecular sieve adsorbent.

[0033] Example 2

[0034] The present embodiment provides a preparation method of a molecular sieve adsorbent applied to synthetic ammonia production, comprising the following steps:

[0035] S1, 12 parts of 3-aminopropyl triethoxysilane and 6 parts of ethylenediamine were dissolved in 52 parts of anhydrous ethanol, 0.6 parts of glacial acetic acid was added to adjust the pH to 6.5, and the reaction was carried out at 65°C under nitrogen protection at a stirring speed of 350 rpm for 3h. After the reaction was completed, the silane precursor was obtained by vacuum concentration, and was stored in a sealed nitrogen atmosphere and protected from light for standby use;

[0036] S2, 6 parts of copper acetate was dissolved in a mixed solvent composed of 22 parts of anhydrous methanol and 8 parts of deionized water, 2.5 parts of ascorbic acid was added under nitrogen protection and 380 rpm stirring, and the reaction was carried out at 42°C for 30 min. Then, 12 parts of the silane precursor was added and the reaction was continued for 1.5h to obtain a composite modification liquid, which was sealed and stored in a nitrogen atmosphere and protected from light;

[0037] S3, 7 parts of sodium silicate, 3 parts of sodium metaaluminate and 1.0 part of sodium hydroxide were dissolved in 42 parts of deionized water, and were fully dissolved at room temperature under stirring at 380 rpm for 25 min. The mixed solution was transferred to a polytetrafluoroethylene-lined reaction kettle, sealed, and crystallized at 102°C for 9h. After cooling, it was filtered and washed with deionized water until the filtrate was neutral. The obtained solid was dried at 110°C with air blowing for 5h, and then calcined at 520°C for 1.5h. The calcined product was ground to pass through a 250 mesh sieve to obtain a molecular sieve matrix;

[0038] S4, 10 parts of the molecular sieve matrix and 2 parts of magnesium chloride were added to 75 parts of deionized water, and ion exchange was carried out at 75°C under stirring at 250 rpm for 2h. After filtration and washing, the product was dried at 110°C for 5h to obtain a composite molecular sieve matrix;

[0039] S5, under nitrogen protection, 10 parts of the composite molecular sieve matrix was immersed in 42 parts of the composite modification liquid, and stirred at room temperature at 300 rpm for 5h. After filtration, the product was vacuum dried at 65°C for 3h, and then heat treated at 380°C at a temperature rising rate of 3°C / min for 2.5h in a nitrogen atmosphere. After cooling, the product was ground to pass through a 200 mesh sieve to obtain a molecular sieve adsorbent.

[0040] Example 3

[0041] The present embodiment provides a preparation method of a molecular sieve adsorbent applied to synthetic ammonia production, which comprises the following steps:

[0042] S1, 15 parts of 3-aminopropyl triethoxysilane and 8 parts of ethylenediamine were dissolved in 55 parts of anhydrous ethanol, 0.8 parts of glacial acetic acid was added to adjust the pH to 7, and the reaction was carried out at 70°C under nitrogen protection at a stirring speed of 400 rpm for 2h. After the reaction was completed, the silane precursor was obtained by vacuum concentration, and was stored in a sealed nitrogen atmosphere and protected from light for standby use;

[0043] S2, 7 parts of copper acetate were dissolved in a mixed solvent composed of 25 parts of anhydrous methanol and 10 parts of deionized water, 3 parts of ascorbic acid were added under the conditions of nitrogen protection and 400 rpm stirring, and the mixture was reacted at 45°C for 25 min, then 15 parts of silane precursor were added and the reaction was continued for 1 h to obtain a composite modification liquid, which was sealed and stored in the dark under nitrogen protection;

[0044] S3, 8 parts of sodium silicate, 4 parts of sodium metaaluminate and 1.2 parts of sodium hydroxide were dissolved in 45 parts of deionized water, and the mixture was stirred at 400 rpm at room temperature for 20 min to fully dissolve, then the mixture was transferred into a polytetrafluoroethylene-lined reaction kettle, sealed, and crystallized at 105°C for 8 h, then filtered and washed with deionized water until the filtrate was neutral, the obtained solid was dried at 120°C for 4 h, then calcined at 550°C for 1 h, and finally ground through a 300 mesh sieve to obtain a molecular sieve matrix;

[0045] S4, 12 parts of the molecular sieve matrix and 3 parts of magnesium chloride were added to 80 parts of deionized water, and the mixture was stirred at 300 rpm at 80°C for 1 h for ion exchange, then filtered, washed and dried at 120°C for 4 h to obtain a composite molecular sieve matrix;

[0046] S5, under nitrogen protection, 12 parts of the composite molecular sieve matrix were immersed in 45 parts of the composite modification liquid, stirred at 350 rpm at room temperature for 4 h, then filtered and vacuum dried at 70°C for 2 h, then heated to 420°C at a rate of 4°C / min in a nitrogen atmosphere and heat-treated for 2 h, then cooled and ground through a 300 mesh sieve to obtain a molecular sieve adsorbent.

[0047] Example 4

[0048] The present embodiment provides a preparation method of a molecular sieve adsorbent applied to synthetic ammonia production, comprising the following steps:

[0049] S1, 15 parts of 3-aminopropyltriethoxysilane and 7 parts of ethylenediamine were dissolved in 55 parts of anhydrous ethanol, 0.8 parts of glacial acetic acid was added to adjust the pH to 7, and the mixture was reacted at 68°C for 2.5 h under nitrogen protection and at a stirring speed of 380 rpm, then vacuum concentrated to obtain a silane precursor, which was sealed, stored in the dark under nitrogen protection and ready for use;

[0050] S2, 6.5 parts of copper acetate were dissolved in a mixed solvent composed of 23 parts of anhydrous methanol and 8 parts of deionized water, 2.8 parts of ascorbic acid were added under the conditions of nitrogen protection and 390 rpm stirring, and the mixture was reacted at 43°C for 28 min, then 14 parts of silane precursor were added and the reaction was continued for 1.2 h to obtain a composite modification liquid, which was sealed and stored in the dark under nitrogen protection;

[0051] S3, 7.5 parts of sodium silicate, 3.5 parts of sodium metaaluminate and 1.1 parts of sodium hydroxide were dissolved in 43 parts of deionized water, and stirred at 390 rpm for 22 min at room temperature to make them fully dissolved, the mixed solution was transferred into a polytetrafluoroethylene-lined reaction kettle and sealed, and crystallized at 103°C for 8.5 h, after cooling, it was filtered and washed with deionized water until the filtrate was neutral, the obtained solid was dried at 115°C for 4.5 h, and then calcined at 530°C for 1.2 h, and ground through a 280 mesh sieve to obtain a molecular sieve matrix;

[0052] S4, 11 parts of the molecular sieve matrix and 2.5 parts of magnesium chloride were added to 78 parts of deionized water, and ion exchange was carried out at 78°C under stirring at 280 rpm for 1.5 h, after filtration and washing, it was dried at 115°C for 4.5 h to obtain a composite molecular sieve matrix;

[0053] S5, under the protection of nitrogen, 11 parts of the composite molecular sieve matrix were immersed in 44 parts of the composite modification liquid, stirred at 320 rpm at room temperature for 4.5 h, filtered, vacuum dried at 68°C for 2.5 h, then heated to 400°C at a rate of 3.5°C / min under a nitrogen atmosphere and heat-treated for 2.2 h, after cooling, it was ground through a 250 mesh sieve to obtain a molecular sieve adsorbent.

[0054] Comparative Example 1

[0055] The difference between this comparative example and Example 4 is that the preparation of the silane precursor is omitted in step S1, and the unmodified 3-aminopropyltriethoxysilane is directly used for the preparation of the composite modification liquid in step S2, and the rest of the steps and parameters are the same as those in Example 4.

[0056] Comparative Example 2

[0057] The difference between this comparative example and Example 4 is that ascorbic acid is not added as a reducing agent in step S2, and copper acetate is directly dissolved in the mixed solvent to react with the silane precursor, and the rest of the steps and parameters are the same as those in Example 4.

[0058] Comparative Example 3

[0059] The difference between this comparative example and Example 4 is that the magnesium ion exchange process is omitted in step S4, and the sodium type molecular sieve matrix is directly used for the immersion treatment in step S5, and the rest of the steps and parameters are the same as those in Example 4.

[0060] Comparative Example 4

[0061] The difference between this comparative example and Example 4 is that ZSM-5 molecular sieve is used instead of the in-situ synthesized sodium type molecular sieve matrix in step S3, and the rest of the steps and parameters are the same as those in Example 4.

[0062] Comparative Example 5

[0063] The comparative example is different from example 4 in that an equivalent amount of sodium borohydride is used instead of ascorbic acid as a reducing agent in step S2, and the remaining steps and parameters are exactly the same as those of example 4.

[0064] Performance test

[0065] The performance of the molecular sieve adsorbents for synthetic ammonia production and the preparation method thereof of examples 1-4 and comparative examples 1-5 were determined, and the test results are shown in Table 1.

[0066] Table 1

[0067] Test item CO2adsorption capacity (mmol / g) Water adsorption capacity (mmol / g) Methanol adsorption capacity (mmol / g) Example 1 6.26 7.86 5.57 Example 2 6.55 8.13 5.82 Example 3 6.35 7.90 5.65 Example 4 6.64 8.33 5.95 Comparative Example 1 4.17 5.21 3.34 Comparative Example 2 3.80 4.94 3.01 Comparative Example 3 4.51 5.87 3.78 Comparative Example 4 4.36 5.52 3.56 Comparative Example 5 4.72 6.09 3.90

[0068] From the table data, it can be seen that the molecular sieve adsorbents of examples 1-4 exhibit superior carbon dioxide, water and methanol adsorption capacity, among which the comprehensive adsorption performance of example 4 is the most outstanding, indicating that it has a highly ordered pore structure and abundant surface active sites, and is suitable for efficient removal of various impurities in synthetic ammonia raw gas.

[0069] In comparison, the adsorption performance of all comparative examples has decreased to varying degrees, among which the adsorption capacity of comparative example 2 is the lowest, with a CO2 adsorption capacity of only 3.80 mmol / g, because the copper species cannot be effectively reduced and dispersed due to the absence of ascorbic acid as a reducing agent; the surface modification of comparative example 1 is insufficient due to the omission of the preparation step of the silane precursor, resulting in a significant reduction of active sites; the pore structure and surface chemical properties of the commercial ZSM-5 molecular sieve used in comparative example 4 do not match the modified components, limiting the development of adsorption performance; comparative example 3 does not perform magnesium ion exchange, and the molecular sieve still remains in sodium type, lacking the structural stability and strong adsorption sites provided by magnesium ions; comparative example 5 uses sodium borohydride instead of ascorbic acid, although it has reducing ability, but the reduction process is too violent and easy to cause metal agglomeration, still resulting in lower adsorption performance than the examples.

[0070] In the description of the specification, the description of the terms "embodiment", "each embodiment" and the like means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or preparation example are contained in at least one embodiment or preparation example of the present application. In the present specification, the illustrative description of the above terms does not necessarily refer to the same embodiment or preparation example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or preparation examples in a suitable manner.

[0071] The above is only a preferred specific embodiment of the present application, but the protection scope of the present application is not limited thereto, and any person skilled in the art can make equivalent substitutions or changes within the technical scope disclosed by the present application according to the technical solution and inventive concept of the present application, which should be covered within the protection scope of the present application.

Claims

1. A process for the preparation of a molecular sieve adsorbent for use in the production of synthetic ammonia, characterized by, It comprises the following steps: S1, 3-aminopropyl triethoxysilane and ethylenediamine are dissolved in anhydrous ethanol, glacial acetic acid is added to adjust the pH, and the reaction is carried out under nitrogen protection, and then vacuum concentration is carried out to obtain a silane precursor, which is sealed and stored in the dark under nitrogen protection; S2, copper acetate is dissolved in a mixed solvent, ascorbic acid is added under stirring and nitrogen protection, and then the silane precursor prepared in S1 is added for continuous stirring and reaction to obtain a composite modification liquid, which is sealed and stored in the dark under nitrogen protection; S3, sodium silicate, sodium metaaluminate and sodium hydroxide are dissolved in deionized water for constant temperature crystallization reaction, and then filtration, washing, drying and calcination are carried out to obtain a molecular sieve matrix; S4, the molecular sieve matrix and magnesium chloride are added into deionized water for ion exchange, and then filtration, washing and drying are carried out to obtain a composite molecular sieve matrix; S5, under nitrogen protection, the composite molecular sieve matrix is impregnated with the composite modification liquid, and then drying and heat treatment are carried out to obtain a molecular sieve adsorbent.

2. The method for producing a molecular sieve adsorbent for use in the production of synthetic ammonia according to claim 1, characterized by, In the step S1, 10-15 parts of 3-aminopropyl triethoxysilane, 5-8 parts of ethylenediamine, 50-55 parts of anhydrous ethanol and 0.5-0.8 parts of glacial acetic acid are used.

3. The method for producing a molecular sieve adsorbent for use in the production of synthetic ammonia according to claim 1, characterized by, In the step S2, 5-7 parts of copper acetate, 25-35 parts of a mixed solvent, 2-3 parts of ascorbic acid and 10-15 parts of the silane precursor are used, and the mixed solvent is composed of 20-25 parts of anhydrous methanol and 5-10 parts of deionized water.

4. The method for producing a molecular sieve adsorbent for use in the production of synthetic ammonia according to claim 1, characterized by, In the step S3, 6-8 parts of sodium silicate, 2-4 parts of sodium metaaluminate, 0.8-1.2 parts of sodium hydroxide and 40-45 parts of deionized water are used.

5. The method for preparing a molecular sieve adsorbent for use in the production of synthetic ammonia according to claim 1, characterized by, In the step S4, 8-12 parts of the molecular sieve matrix, 1-3 parts of magnesium chloride and 70-80 parts of deionized water are used.

6. The method for preparing a molecular sieve adsorbent for use in the production of synthetic ammonia according to claim 1, characterized by, In the step S5, 8-12 parts of the composite molecular sieve matrix and 40-45 parts of the composite modification liquid are used.

7. The method for producing a molecular sieve adsorbent for use in the production of synthetic ammonia according to claim 1, characterized by, In the step S1, the reaction is carried out at 60-70℃ for 2-4h.

8. The method for producing a molecular sieve adsorbent for use in the production of synthetic ammonia according to claim 1, characterized by, In the step S2, the reaction after adding ascorbic acid is carried out at 40-45℃ for 25-35min, and the reaction after adding the silane precursor is continued for 1-2h; in the step S3, the constant temperature crystallization is carried out at 100-105℃ for 8-10h.

9. The method for preparing a molecular sieve adsorbent for use in the production of synthetic ammonia according to claim 1, characterized by, In the step S4, the ion exchange is carried out at 70-80℃ for 1-3h; in the step S5, the impregnation time is 4-6h, the temperature is raised to 350-420℃ at a rate of 2-4℃ / min during the heat treatment process, and the temperature is maintained at 350-420℃ for 2-3h.

10. A molecular sieve adsorbent for use in the production of synthetic ammonia, characterized by, The molecular sieve adsorbent is prepared by the method of any one of claims 1-9. The molecular sieve adsorbent is prepared by the method of any one of claims 1-9.