Preparation method of modified molecular sieve adsorbent

Abstract

According to the preparation method of the modified molecular sieve adsorbent provided by the invention, the molecular sieve is subjected to pore modification, amine modification, two times of modification and carbon dioxide adsorption, the carbon dioxide adsorption amount is 4.0 mmol / g or above, the adsorbent can be recycled for multiple times, the used adsorbent can be subjected to desorption treatment for recycling, the consumption is low, and the problems of solvent loss and the like are avoided; the problems of high energy consumption and solvent loss and recovery of a traditional absorption method are overcome.

Description

Technical Field

[0001] The invention belongs to the technical field of gas adsorption, and specifically, is a method for preparing a modified molecular sieve adsorbent. Background Art

[0002] Carbon dioxide emissions mainly come from the combustion and conversion of fossil fuels (coal, oil, natural gas, etc.). With the determination of my country's dual carbon goals, it is of great significance to capture and store (CCS) CO2 emitted by various industries.

[0003] The main methods for capturing carbon dioxide include absorption, adsorption, membrane separation, and cryogenic freezing. At present, the most mature and widely used carbon dioxide capture technology is the absorption method, but it consumes a lot of energy, and the loss and recovery of solvents need to be solved urgently; the membrane separation method has high manufacturing costs, and it is easy to scale during operation, resulting in low permeability, and unstable operation in humid environments. The adsorbent of the adsorption method can be recycled and is suitable for low CO2 concentration gas streams. It is easier to separate and has been widely studied in recent years. However, due to the low CO2 adsorption capacity of solid adsorbents, its industrial application faces challenges.

[0004] Molecular sieves have been widely studied as catalysts. In recent years, due to their unique morphology and structure, molecular sieves have been increasingly studied as CO2 adsorbents. Modified molecular sieves as adsorbents will be the focus of future research.

[0005] Chinese patent CN201310509561.X, a ZSM-5 molecular sieve modified catalyst and its preparation method, using ZSM-5 molecular sieve as a carrier, through group grafting and surface modification to make a loaded modified catalyst, which is used in a fixed bed reactor for the preparation of ethylene by dehydration of low-concentration acetic acid.

[0006] Chinese patent CN202210261958.0, a modified molecular sieve for CO2 adsorption separation and its preparation method and device, the molecular sieve is vacuum degassed and activated, the organic amine is deposited on the molecular sieve, and the modified molecular sieve is obtained by vacuum degassing. The vacuum gas phase step-by-step dynamic deposition is adopted to overcome the shortcomings of the traditional organic amine impregnation method of uneven loading and easy pore blockage, no waste liquid is generated, and it is easy to industrialize mass production.

[0007] Chinese patent CN202211600250.X, a Zn-MOR molecular sieve and its application in the adsorption and separation of CO2 in low-carbon hydrocarbons, mixes zinc salt, sodium aluminate, sodium hydroxide, silicon source and water, and hydrothermally crystallizes the obtained gel to obtain zinc-containing MOR heteroatom molecular sieve. The synthesis process is simple and the product cost is low. It is the first molecular sieve material to achieve CO2 capture by CO2 / C2H2. Summary of the invention

[0008] The purpose of the present invention is to provide a method for preparing a modified molecular sieve adsorbent. The molecular sieve is subjected to pore modification and then amine modification. After the two modifications, a carbon dioxide adsorption test is carried out. The carbon dioxide adsorption amount is above 4.0 mmol / g, and the adsorbent can be recycled for multiple times. The used adsorbent can be desorbed and reused.

[0009] The present invention provides a method for preparing a molecular sieve adsorbent. After the molecular sieve carrier is subjected to pretreatment, pore modification, primary loading and secondary loading, the molecular sieve adsorbent is obtained and used for adsorbing CO2 gas.

[0010] Generally, the preparation steps of the molecular sieve adsorbent are: (1) Pretreatment: The molecular sieve carrier is acid-washed, with the mass ratio of the molecular sieve carrier to the acid being 1:0.5-1:10. After stirring for 0.5 h-3 h, the carrier is washed with distilled water until neutral, filtered, and dried. (2) Modified molecular sieve: The pretreated molecular sieve is modified to change the pore size and the internal pores, and is modified with a modifier. The treatment temperature is 5°C-100°C, the treatment time is 0.5 h-8 h, and the immersion time is 0.5 h-24 h. After modification, the molecular sieve is washed to neutrality, filtered, and dried. (3) Loading molecular sieve once: Under microwave induction, the modified molecular sieve is loaded with amine solution, stirred and allowed to stand for 0.5 h to 8 h; the same type of amine solution is added again for loading, stirred and allowed to stand for the same time, microwave induction is stopped, and the molecular sieve is filtered and dried; (4) Secondary loading of molecular sieve: The molecular sieve after primary loading is ultrasonically loaded with an aminosilane solvent, filtered and dried to prepare a molecular sieve adsorbent.

[0011] Preferably, the acid in step (1) comprises nitric acid, sulfuric acid or hydrochloric acid.

[0012] The modifier described in step (2) is one of hydrogen peroxide, phosphoric acid, sodium hypochlorite, perchloric acid, sodium hydroxide and potassium hydroxide.

[0013] The molecular sieve is of MCM-41, ZSM-5, SAPO-34, MOR or NaY type.

[0014] The microwave power in step (3) is 600-800 W, and the microwave irradiation time is 5-10 min.

[0015] The amine solution in step (3) is at least one of monoethanolamine, diethanolamine, diethylenetriamine, triethanolamine, diisopropanolamine, 2-aminoisobutanol, N-methylmonoethanolamine and N-methyldiethanolamine.

[0016] The aminosilane in step (4) is one of bis(dimethylaminodimethylsilane) and aminopropyltriethoxysilane.

[0017] In step (4), the ultrasonic dispersion loading time is 30 min-60 min, and the ultrasonic dispersion loading temperature is 50°C-80°C.

[0018] The molecular sieve adsorbent prepared by the method of the present invention can be used to adsorb CO2 gas. A fixed bed reactor containing a glass adsorption column is used to adsorb CO2, and the inlet and outlet CO2 content is measured by gas chromatography.

[0019] The preparation method of the modified molecular sieve adsorbent provided by the present invention comprises the following steps: firstly subjecting the molecular sieve to pore modification and then subjecting it to amine modification; and after the two modifications, a carbon dioxide adsorption test is conducted, wherein the carbon dioxide adsorption amount is above 4.0 mmol / g and the adsorbent can be recycled for multiple times; and the used adsorbent can be desorbed and reused, with low consumption and no problems such as solvent loss, thereby overcoming the problems of high energy consumption and solvent loss and recovery in traditional absorption methods. Implementation

[0020] The present invention is described in detail below with reference to the embodiments. Example 1

[0021] Molecular sieve adsorbent preparation: (1) Pretreatment: Take 10 g of ZSM-5 molecular sieve, add 50 mL of 20% nitric acid, stir with a magnetic stirrer for 0.5 h, wash with distilled water to neutrality, filter and dry; (2) Modified molecular sieve: Add 100 mL of 30% H2O2 and stir at 20°C for 2 h. After soaking for 20 h, wash to neutrality and dry at 150°C. (3) Loading molecular sieves once: Adjust the microwave power to 800 W, place the modified molecular sieves in 20 mL of monoethanolamine solution, stir with a magnetic stirrer for 10 min, let stand for 4 h, add 10 mL of monoethanolamine solution again, stir with a magnetic stirrer for 10 min, let stand for 4 h, stop microwave induction, filter and dry; (4) Secondary loading of molecular sieve: The molecular sieve after the primary loading was placed in 10 mL of bis(dimethylaminodimethylsilane) solution for ultrasonic loading at a temperature of 60°C for 30 min, filtered and dried to prepare a molecular sieve adsorbent; Adsorption of CO2: The fixed bed reactor contains a glass adsorption column, and the temperature of the adsorption column is controlled by a heating furnace. During the adsorption process, 10g of molecular sieve adsorbent is loaded into the adsorption column, and a dry CO2 / N2 mixed gas (CO2 content of 12.5 wt%) is passed through the pipeline at a flow rate of 40 mL / min. The inlet and outlet CO2 content is measured by gas chromatography. The CO2 adsorption amount is 4.8mmol / g. Example 2

[0022] Molecular sieve adsorbent preparation: (1) Pretreatment: Take 10 g of ZSM-5 molecular sieve, add 50 mL of 10% hydrochloric acid, stir with a magnetic stirrer at 20 °C for 3 h, wash with distilled water to neutrality, filter and dry; (2) Modified molecular sieve: Add 100 mL of 30% H2O2 and stir at 40 °C for 4 h. After soaking for 24 h, wash to neutrality and dry at 150 °C. (3) Loading molecular sieves once: Adjust the microwave power to 800 W, place the modified molecular sieves in 20 mL of diethanolamine solution, stir with a magnetic stirrer for 5 min, let stand for 0.5 h, add 10 mL of monoethanolamine solution again, stir with a magnetic stirrer for 5 min, let stand for 0.5 h, stop microwave induction, filter and dry; (4) Secondary loading of molecular sieve: The molecular sieve after the primary loading was placed in 10 mL of aminopropyltriethoxysilane solution for ultrasonic loading at a temperature of 50 °C for 40 min, filtered and dried to prepare a molecular sieve adsorbent; Adsorption of CO2: The fixed bed reactor contains a glass adsorption column, and the temperature of the adsorption column is controlled by a heating furnace. During the adsorption process, 10g of molecular sieve adsorbent is loaded into the adsorption column, and a dry CO2 / N2 mixed gas (CO2 content of 12.5 wt%) is passed through the pipeline at a flow rate of 40 mL / min. The inlet and outlet CO2 content is measured by gas chromatography. The CO2 adsorption amount is 4.5mmol / g. Example 3

[0023] Molecular sieve adsorbent preparation: (1) Pretreatment: Take 10 g of ZSM-5 molecular sieve, add 100 mL of 20% nitric acid, stir with a magnetic stirrer at 20 °C for 1 h, wash with distilled water to neutrality, filter and dry; (2) Modified molecular sieve: Add 100 mL of 30% H2O2 and stir at 40 °C for 6 h, soak for 0.5 h, wash to neutrality, and dry at 150 °C; (3) Loading molecular sieves once: Adjust the microwave power to 800 W, place the modified molecular sieves in 20 mL of triethylenetriamine solution, stir with a magnetic stirrer for 10 min, let stand for 8 h, add 10 mL of triethylenetriamine solution again, stir with a magnetic stirrer for 10 min, let stand for 8 h, stop microwave induction, filter and dry; (4) Secondary loading of molecular sieve: The molecular sieve after the primary loading was placed in 10 mL of aminopropyltriethoxysilane solution for ultrasonic loading at a temperature of 70 °C for 50 min, filtered and dried to prepare a molecular sieve adsorbent; Adsorption of CO2: The fixed bed reactor contains a glass adsorption column, and the temperature of the adsorption column is controlled by a heating furnace. During the adsorption process, 10g of molecular sieve adsorbent is loaded into the adsorption column, and a dry CO2 / N2 mixed gas (CO2 content of 12.5 wt%) is passed through the pipeline at a flow rate of 40 mL / min. The inlet and outlet CO2 content is measured by gas chromatography. The CO2 adsorption amount is 4.7mmol / g. Example 4

[0024] Molecular sieve adsorbent preparation: (1) Pretreatment: Take 10 g of ZSM-5 molecular sieve, add 50 mL of 5% nitric acid, stir with a magnetic stirrer at 20 °C for 2 h, wash with distilled water to neutrality, filter and dry; (2) Modified molecular sieve: Add 100 mL of 30% H2O2 and stir at 80°C for 8 h. After soaking for 10 h, wash to neutrality and dry at 150°C. (3) Loading molecular sieves once: Adjust the microwave power to 600 W, place the modified molecular sieves in 20 mL of monoethanolamine solution, stir with a magnetic stirrer for 5 min, let stand for 2 h, add 10 mL of monoethanolamine solution again, stir with a magnetic stirrer for 5 min, let stand for 2 h, stop microwave induction, filter and dry; (4) Secondary loading of molecular sieve: The molecular sieve after the primary loading was placed in 10 mL of bis(dimethylaminodimethylsilane) solution for ultrasonic loading at a temperature of 80 °C for 60 min, filtered and dried to prepare a molecular sieve adsorbent; Adsorption of CO2: The fixed bed reactor contains a glass adsorption column, and the temperature of the adsorption column is controlled by a heating furnace. During the adsorption process, 10g of molecular sieve adsorbent is loaded into the adsorption column, and a dry CO2 / N2 mixed gas (CO2 content of 12.5 wt%) is passed through the pipeline at a flow rate of 40 mL / min. The inlet and outlet CO2 content is measured by gas chromatography. The CO2 adsorption amount is 4.8mmol / g. Example 5

[0025] Molecular sieve adsorbent preparation: (1) Pretreatment: Take 10 g of MCM-41 molecular sieve, add 50 mL of 20% nitric acid, stir with a magnetic stirrer at 20 °C for 1.5 h, wash with distilled water to neutrality, filter and dry; (2) Modified molecular sieve: Add 100 mL of 20% sodium hydroxide and stir at 100 °C for 0.5 h. After soaking for 15 h, wash until neutral and dry at 150 °C. (3) Loading molecular sieves once: Adjust the microwave power to 700 W, place the modified molecular sieves in 20 mL of triethanolamine solution, stir with a magnetic stirrer for 8 min, let stand for 4 h, add 10 mL of triethanolamine solution again, stir with a magnetic stirrer for 8 min, let stand for 4 h, stop microwave induction, filter and dry; (4) Secondary loading of molecular sieve: The molecular sieve after the primary loading was placed in 10 mL of bis(dimethylaminodimethylsilane) solution for ultrasonic loading at a temperature of 60°C for 30 min, filtered and dried to prepare a molecular sieve adsorbent; Adsorption of CO2: The fixed bed reactor contains a glass adsorption column, and the temperature of the adsorption column is controlled by a heating furnace. During the adsorption process, 10g of molecular sieve adsorbent is loaded into the adsorption column, and a dry CO2 / N2 mixed gas (CO2 content of 12.5 wt%) is passed through the pipeline at a flow rate of 40 mL / min. The inlet and outlet CO2 content is measured by gas chromatography. The CO2 adsorption amount is 4.0mmol / g. Example 6

[0026] Molecular sieve adsorbent preparation: (1) Pretreatment: Take 10 g of MCM-41 molecular sieve, add 50 mL of 20% nitric acid, stir with a magnetic stirrer at 20 °C for 2.5 h, wash with distilled water to neutrality, filter and dry; (2) Modified molecular sieve: Add 100 mL of 10% phosphoric acid and stir at 5 °C for 3 h. After soaking for 5 h, wash until neutral and dry at 150 °C. (3) Loading molecular sieves once: Adjust the microwave power to 800 W, place the modified molecular sieves in 20 mL of N-methyldiethanolamine, stir with a magnetic stirrer for 6 min, let stand for 6 h, add 10 mL of N-methyldiethanolamine solution again, stir with a magnetic stirrer for 6 min, let stand for 6 h, stop microwave induction, filter and dry; (4) Secondary loading of molecular sieve: The molecular sieve after the primary loading was placed in 10 mL of aminopropyltriethoxysilane solution for ultrasonic loading at a temperature of 60 °C for 30 min, filtered and dried to prepare a molecular sieve adsorbent; Adsorption of CO2: The fixed bed reactor contains a glass adsorption column, and the temperature of the adsorption column is controlled by a heating furnace. During the adsorption process, 10g of molecular sieve adsorbent is loaded into the adsorption column, and a dry CO2 / N2 mixed gas (CO2 content of 12.5 wt%) is passed through the pipeline at a flow rate of 40 mL / min. The inlet and outlet CO2 content is measured by gas chromatography. The CO2 adsorption amount is 4.1mmol / g. Example 7

[0027] Molecular sieve adsorbent preparation: (1) Pretreatment: Take 10 g of SAPO-34 molecular sieve, add 50 mL of 20% nitric acid, stir with a magnetic stirrer at 20 °C for 0.5 h, wash with distilled water to neutrality, filter and dry; (2) Modified molecular sieve: Add 100 mL of 10% sodium hydroxide and stir at 20 °C for 1 h, soak for 7 h, wash to neutrality, and dry at 150 °C; (3) Loading molecular sieves once: Adjust the microwave power to 800 W, place the modified molecular sieves in 20 mL of monoethanolamine, stir with a magnetic stirrer for 10 min, let stand for 4 h, add 10 mL of monoethanolamine solution again, stir with a magnetic stirrer for 10 min, let stand for 4 h, stop microwave induction, filter and dry; (4) Secondary loading of molecular sieve: The molecular sieve after the primary loading was placed in 10 mL of bis(dimethylaminodimethylsilane) solution for ultrasonic loading at a temperature of 60°C for 40 min, filtered and dried to prepare a molecular sieve adsorbent; Adsorption of CO2: The fixed bed reactor contains a glass adsorption column, and the temperature of the adsorption column is controlled by a heating furnace. During the adsorption process, 10g of molecular sieve adsorbent is loaded into the adsorption column, and a dry CO2 / N2 mixed gas (CO2 content of 12.5 wt%) is passed through the pipeline at a flow rate of 40 mL / min. The inlet and outlet CO2 content is measured by gas chromatography. The CO2 adsorption amount is 4.0mmol / g.

[0028] Comparative Example 1: Molecular sieve adsorbent preparation: (1) Pretreatment: Take 10 g of ZSM-5 molecular sieve, add 50 mL of 20% nitric acid, stir with a magnetic stirrer for 0.5 h, wash with distilled water to neutrality, filter and dry; (2) Modified molecular sieve: Add 100 mL of 30% H2O2 and stir at 20°C for 2 h. After soaking for 20 h, wash to neutrality and dry at 150°C. (3) Loading molecular sieves once: Adjust the microwave power to 800 W, place the modified molecular sieves in 20 mL of monoethanolamine solution, stir with a magnetic stirrer for 10 min, let stand for 4 h, add 10 mL of monoethanolamine solution again, stir with a magnetic stirrer for 10 min, let stand for 4 h, stop microwave induction, filter and dry.

[0029] Adsorption of CO2: The fixed bed reactor contains a glass adsorption column, and the temperature of the adsorption column is controlled by a heating furnace. During the adsorption process, 10g of molecular sieve adsorbent is loaded into the adsorption column, and a dry CO2 / N2 mixed gas (CO2 content of 12.5 wt%) is passed through the pipeline at a flow rate of 40 mL / min. The inlet and outlet CO2 content is measured by gas chromatography. The CO2 adsorption amount is 2.0mmol / g.

[0030] Comparative Example 2: Molecular sieve adsorbent preparation: (1) Pretreatment: Take 10 g of ZSM-5 molecular sieve, add 50 mL of 20% nitric acid, stir with a magnetic stirrer for 0.5 h, wash with distilled water to neutrality, filter and dry; (2) Modified molecular sieve: Add 100 mL of 30% H2O2 and stir at 20°C for 2 h. After soaking for 20 h, wash to neutrality and dry at 150°C. (3) Primary loading of molecular sieve: Adjust the microwave power to 800 W, place the modified molecular sieve in 20 mL of monoethanolamine solution, stir with a magnetic stirrer for 10 min, let stand for 4 h, stop microwave induction, filter and dry; (4) Secondary loading of molecular sieve: The molecular sieve after the primary loading was placed in 10 mL of bis(dimethylaminodimethylsilane) solution for ultrasonic loading at a temperature of 60°C for 30 min, filtered and dried to prepare a molecular sieve adsorbent; Adsorption of CO2: The fixed bed reactor contains a glass adsorption column, and the temperature of the adsorption column is controlled by a heating furnace. During the adsorption process, 10g of molecular sieve adsorbent is loaded into the adsorption column, and a dry CO2 / N2 mixed gas (CO2 content of 12.5 wt%) is passed through the pipeline at a flow rate of 40 mL / min. The inlet and outlet CO2 content is measured by gas chromatography. The CO2 adsorption amount is 2.6mmol / g.

[0031] Comparative Example 3: Molecular sieve adsorbent preparation: (1) Pretreatment: Take 10 g of ZSM-5 molecular sieve, add 50 mL of 20% nitric acid, stir with a magnetic stirrer for 0.5 h, wash with distilled water to neutrality, filter and dry; (2) Modified molecular sieve: Add 100 mL of 30% H2O2 and stir at 20°C for 2 h. After soaking for 20 h, wash to neutrality and dry at 150°C. (3) Loading molecular sieves once: Adjust the microwave power to 800 W, place the modified molecular sieves in 20 mL of monoethanolamine solution, stir with a magnetic stirrer for 10 min, let stand for 4 h, add 10 mL of monoethanolamine solution again, stir with a magnetic stirrer for 10 min, let stand for 4 h, stop microwave induction, filter and dry; (4) Secondary loading of molecular sieve: The molecular sieve after primary loading is placed in 10 mL of bis(dimethylaminodimethylsilane) solution for impregnation loading, filtered and dried to prepare a molecular sieve adsorbent; Adsorption of CO2: The fixed bed reactor contains a glass adsorption column, and the temperature of the adsorption column is controlled by a heating furnace. During the adsorption process, 10g of molecular sieve adsorbent is loaded into the adsorption column, and a dry CO2 / N2 mixed gas (CO2 content of 12.5 wt%) is passed through the pipeline at a flow rate of 40 mL / min. The inlet and outlet CO2 content is measured by gas chromatography. The CO2 adsorption amount is 3.0mmol / g.

[0032] Comparative Example 4: Molecular sieve adsorbent preparation: (1) Pretreatment: Take 10 g of ZSM-5 molecular sieve, add 50 mL of 20% nitric acid, stir with a magnetic stirrer for 0.5 h, wash with distilled water to neutrality, filter and dry; (2) Modified molecular sieve: Add 100 mL of 30% H2O2 and stir at 20°C for 2 h. After soaking for 20 h, wash to neutrality and dry at 150°C. (3) Primary loading of molecular sieves: Place the modified molecular sieves in 20 mL of monoethanolamine solution, stir with a magnetic stirrer for 10 min, let stand for 4 h, add 10 mL of monoethanolamine solution again, stir with a magnetic stirrer for 10 min, let stand for 4 h, stop microwave induction, filter and dry; (4) Secondary loading of molecular sieve: The molecular sieve after the primary loading was placed in 10 mL of bis(dimethylaminodimethylsilane) solution for ultrasonic loading at a temperature of 60°C for 30 min, filtered and dried to prepare a molecular sieve adsorbent; Adsorption of CO2: The fixed bed reactor contains a glass adsorption column, and the temperature of the adsorption column is controlled by a heating furnace. During the adsorption process, 10g of molecular sieve adsorbent is loaded into the adsorption column, and a dry CO2 / N2 mixed gas (CO2 content of 12.5 wt%) is passed through the pipeline at a flow rate of 40 mL / min. The inlet and outlet CO2 content is measured by gas chromatography. The CO2 adsorption amount is 3.4mmol / g.

[0033] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the present invention can be implemented in other specific forms without departing from the spirit or essential features of the present invention. Therefore, the embodiments should be considered exemplary and non-restrictive in all respects, and the scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims be included in the present invention.

[0034] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A method for preparing a molecular sieve adsorbent, characterized in that: The molecular sieve carrier is subjected to pretreatment, pore modification, primary loading and secondary loading to obtain a molecular sieve adsorbent.

2. The preparation method according to claim 1, characterized in that: The preparation steps of molecular sieve adsorbent are: (1) Pretreatment: The molecular sieve carrier is acid-washed, with the mass ratio of the molecular sieve carrier to the acid being 1:0.5-1:

10. After stirring for 0.5h-3h, the carrier is washed with distilled water until neutral, filtered, and dried. (2) Modified molecular sieve: The pretreated molecular sieve is modified to change the pore size and the internal pores, and is modified with a modifier. The treatment temperature is 5°C-100°C, the treatment time is 0.5 h-8 h, and the immersion time is 0.5 h-24 h. After modification, the molecular sieve is washed to neutrality, filtered, and dried. (3) Loading molecular sieve once: Under microwave induction, the modified molecular sieve is loaded with amine solution, stirred and allowed to stand for 0.5 h to 8 h; the same type of amine solution is added again for loading, stirred and allowed to stand for the same time, microwave induction is stopped, and the molecular sieve is filtered and dried; (4) Secondary loading of molecular sieve: The molecular sieve after the primary loading is ultrasonically loaded with an aminosilane solvent, filtered and dried to prepare a molecular sieve adsorbent.

3. The preparation method according to claim 2, characterized in that The acid described in step (1) includes nitric acid, sulfuric acid and hydrochloric acid.

4. The preparation method according to claim 2, characterized in that The modifier described in step (2) is one of hydrogen peroxide, phosphoric acid, sodium hypochlorite, perchloric acid, sodium hydroxide and potassium hydroxide.

5. The preparation method according to claim 1 or 2, characterized in that The molecular sieve is of MCM-41, ZSM-5, SAPO-34, MOR or NaY type.

6. The preparation method according to claim 2, characterized in that The microwave power in step (3) is 600-800 W, and the microwave irradiation time is 5-10 min.

7. The preparation method according to claim 2, characterized in that The amine solution in step (3) is at least one of monoethanolamine, diethanolamine, diethylenetriamine, triethanolamine, diisopropanolamine, 2-aminoisobutanol, N-methylmonoethanolamine and N-methyldiethanolamine.

8. The preparation method according to claim 2, characterized in that The aminosilane in step (4) is one of bis(dimethylaminodimethylsilane) and aminopropyltriethoxysilane.

9. The preparation method according to claim 2, characterized in that In step (4), the ultrasonic dispersion loading time is 30 min-60 min, and the ultrasonic dispersion loading temperature is 50°C-80°C.

10. The preparation method according to claim 1, characterized in that The prepared molecular sieve adsorbent is used to adsorb CO2 gas, and a fixed bed reactor containing a glass adsorption column is used to adsorb CO2.