Molecular sieve as well as preparation method and application thereof in nitrogen separation

Abstract

The invention relates to the technical field of molecular sieves, in particular to a molecular sieve and a preparation method and application thereof in nitrogen separation.The preparation method comprises the steps that a carbonized material and 3-chloropropyltrimethoxysilane are added into methylbenzene, heating is conducted under nitrogen protection till a reflux reaction is conducted for 12-48 h, after the reaction is finished, the room temperature is recovered, filtering is conducted, a product is collected, washing and drying are conducted, and a modified carbonized material is obtained; and adding the modified carbonized material and an ionic liquid into absolute ethyl alcohol, heating to reflux reaction for 12-48 hours, after the reaction is finished, recovering to room temperature, filtering, collecting a product, performing Soxhlet extraction with dichloromethane for 12-48 hours, drying to obtain an immobilized ionic liquid carbonized material, and performing CO2 activation and vapor deposition on the immobilized ionic liquid carbonized material to obtain the molecular sieve. The molecular sieve prepared by the invention has a relatively high specific surface area, and shows excellent performance of selectively adsorbing nitrogen in a methane and nitrogen mixed system.

Description

Technical Field

[0001] The present invention relates to the technical field of molecular sieves, in particular to a molecular sieve and a preparation method thereof and application thereof in nitrogen separation. Background Art

[0002] Natural gas is a clean fossil energy with strong demand and wide application. As the demand for natural gas becomes more and more urgent, separating and purifying low-quality natural gas that does not meet the natural gas qualification standards to meet the use requirements has become a current research hotspot. The main component of natural gas is methane (CH4), which usually also contains various impurities such as water (H2O), nitrogen (N2), oxygen (O2), carbon dioxide (CO2), sulfides and heavy hydrocarbons, which reduce the calorific value of natural gas and affect its transportation safety. Among the many impurities, N2 and CH4 have similar physical properties, making the removal of N2 the most difficult.

[0003] At present, the main methods for separating CH4 / N2 mixed gases include cryogenic separation, membrane separation and pressure swing adsorption. Cryogenic separation and membrane separation have the problem of high cost and energy consumption when used for large-scale mixed gas separation. Pressure swing adsorption technology is based on the adsorption difference of different gas components on the adsorbent, combined with the change of gas adsorption amount under different pressures, to achieve mixed gas separation.

[0004] Adsorbent is the core of pressure swing adsorption technology, and developing adsorbent with high adsorption capacity and high selectivity is the key to pressure swing adsorption technology. Carbon molecular sieve is a popular adsorbent used in CH4 / N2 mixed gas separation, but currently carbon molecular sieve still has problems such as low specific surface area and separation coefficient, which need further research and improvement. Summary of the invention

[0005] Purpose of the invention: In view of the above technical problems, the present invention proposes a molecular sieve and a preparation method thereof and application in nitrogen separation.

[0006] The technical solutions adopted are as follows: A method for preparing a molecular sieve is as follows: In a nitrogen atmosphere, the biomass raw material is heated to 500-600°C and kept at this temperature for 30-60 minutes before being crushed to obtain a pre-carbonized powder; Pre-carbonized powder, phenolic resin powder, coal tar and polyethylene glycol are mixed and then extruded to obtain pellets, which are then heated to 800-1000° C. and carbonized for 1-3 hours to obtain carbonized material; Add the carbonized material and 3-chloropropyltrimethoxysilane into toluene, heat to reflux for reaction for 12-48 hours under nitrogen protection, return to room temperature after the reaction is completed, filter, collect the product, wash and dry to obtain the modified carbonized material; Add the modified carbonized material and the ionic liquid into anhydrous ethanol, heat to reflux for reaction for 12-48 hours, return to room temperature after the reaction is completed, filter, collect the product, extract with dichloromethane for 12-48 hours, and then dry to obtain the immobilized ionic liquid carbonized material; Activate the immobilized ionic liquid carbonized material at a CO2 flow rate of 100-500 ml / min and a temperature of 600-800°C for 1-3 hours; Then, vapor deposition is carried out, with nitrogen as carrier gas, the vapor deposition temperature is 700-900°C, the vapor deposition time is 90-120min, and the vapor deposition is cooled to room temperature after completion.

[0007] Furthermore, the biomass raw material is nut shells.

[0008] The nut shells specifically include hazelnut shells, walnut shells, almond shells, cashew shells, almond shells, pine nut shells, chestnut shells, pistachio shells, and macadamia shells, preferably walnut shells.

[0009] Furthermore, the mass ratio of the pre-carbonized powder, phenolic resin powder, coal tar and polyethylene glycol is 1:0.1-0.3:0.1-0.3:0.01-0.1.

[0010] Furthermore, the mass ratio of the carbonized material to 3-chloropropyltrimethoxysilane is 1:0.1-0.5.

[0011] Furthermore, the mass ratio of the modified carbonized material to the ionic liquid is 1:0.1-0.5.

[0012] Furthermore, the ionic liquid is 1-aminopropyl-3-methylimidazolium lysine salt.

[0013] Furthermore, the deposition gas is any one of benzene, toluene and xylene, or a mixture of two or more thereof.

[0014] Furthermore, the carrier gas flow rate is 100-500 ml / min, and the deposition gas flow rate is 0.1-1 ml / min.

[0015] The present invention also provides a molecular sieve, which is specifically prepared by the above preparation method.

[0016] The present invention also provides an application of the molecular sieve in nitrogen separation.

[0017] Beneficial effects of the present invention: The present invention provides a molecular sieve. Due to the unsaturation of activated carbon atoms, the carbonized material will chemically combine atoms and atomic groups other than carbon components to form various surface functional groups such as hydroxyl groups. The hydroxyl groups on the carbonized material react with 3-chloropropyltrimethoxysilane and then react with ionic liquid to immobilize it. The carbonized material after immobilizing the ionic liquid can promote the transfer and absorption of CO2 through the interaction between lysine and CO2, and realize the diffusion of CO2 in the core parts of carbonized material particles and microdomains, thereby effectively forming pores and increasing its specific surface area, laying a foundation for the next step of gas phase deposition to adjust the pore size. The molecular sieve prepared by the present invention has a high specific surface area and shows excellent selective nitrogen adsorption performance in a methane nitrogen mixed system. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a reaction flow chart of the immobilized ionic liquid carbonized material prepared in Example 1. DETAILED DESCRIPTION

[0019] If the specific conditions are not specified in the examples, the experiments were carried out under conventional conditions or the conditions recommended by the manufacturer. If the manufacturer of the reagents or instruments is not specified, they are all conventional products that can be purchased commercially. The techniques not mentioned in the present invention are all referenced to the prior art. Unless otherwise specified, the following examples and comparative examples are parallel experiments, using the same processing steps and parameters.

[0020] Embodiment 1: A method for preparing a molecular sieve is as follows: In a nitrogen atmosphere, walnut shells with a particle size of 0.25-2 mm were heated to 550°C at a rate of 10°C / min and kept warm for 45 minutes. After returning to room temperature, they were crushed to less than 10 μm to obtain pre-carbonized powder. Pre-carbonized powder, 2124 phenolic resin powder, coal tar and polyethylene glycol 400 in a mass ratio of 1:0.2:0.15:0.05 were fully mixed and stirred in a kneader, and then extruded into pellets by a tablet press, which were heated to 1000°C at a speed of 10°C / min and carbonized for 2 hours to obtain a carbonized material; 10g of carbonized material and 2g of 3-chloropropyltrimethoxysilane were added to 100ml of toluene, and heated to reflux for 24h under nitrogen protection. After the reaction, the room temperature was restored, and the product was filtered and collected. The product was washed with anhydrous ethanol and dried to obtain a modified carbonized material. Figure 1 Middle S1; 10g of 1-aminopropyl-3-methylimidazolium hexafluorophosphate was added to 500ml of deionized water, and the obtained solution was passed through an anion exchange resin to obtain a 1-aminopropyl-3-methylimidazolium hydroxide solution. A sample was taken and titrated with 0.1mol / L hydrochloric acid to calculate the required amount of lysine. Lysine was dissolved in an appropriate amount of deionized water and added to the 1-aminopropyl-3-methylimidazolium hydroxide solution. After stirring at room temperature for 24h, it was concentrated under reduced pressure to remove water and low-boiling substances, and then vacuum dried at 55℃ for 48h. Then, it was added to a mixed solvent composed of acetonitrile and methanol (volume ratio 9:1) with a solid-liquid mass ratio of 1:10 and stirred for 8h. Then, it was cooled at -5℃ to precipitate the unreacted lysine. After filtering, the filtrate was concentrated under reduced pressure and vacuum dried to obtain 1-aminopropyl-3-methylimidazolium lysine salt. 10g of modified carbonized material and 2.7g of 1-aminopropyl-3-methylimidazolium lysine salt were added to 100ml of anhydrous ethanol, heated to reflux for 24h, and returned to room temperature after the reaction was completed. The product was collected by filtration, extracted with dichloromethane for 12h, and then dried to obtain a carbonized material with immobilized ionic liquid. Figure 1 Middle S2; The solid-supported ionic liquid carbonized material was activated for 2 hours at a CO2 flow rate of 200 ml / min and a temperature of 700°C, and then vapor deposited. During vapor deposition, nitrogen was used as the carrier gas, benzene was used as the deposition gas, the vapor deposition temperature was 700°C, the vapor deposition time was 120 minutes, the carrier gas flow rate was 200 ml / min, the deposition gas flow rate was 0.5 ml / min, and the material was cooled to room temperature after vapor deposition.

[0021] Embodiment 2: A method for preparing a molecular sieve is as follows: In a nitrogen atmosphere, walnut shells with a particle size of 0.25-2 mm were heated to 550°C at a rate of 10°C / min and kept warm for 45 minutes. After returning to room temperature, they were crushed to less than 10 μm to obtain pre-carbonized powder. Pre-carbonized powder, 2124 phenolic resin powder, coal tar and polyethylene glycol 400 in a mass ratio of 1:0.2:0.15:0.05 were fully mixed and stirred in a kneader, and then extruded into pellets by a tablet press, which were heated to 1000°C at a speed of 10°C / min and carbonized for 2 hours to obtain a carbonized material; 10 g of carbonized material and 2 g of 3-chloropropyltrimethoxysilane were added to 100 ml of toluene, and heated to reflux for 24 h under nitrogen protection. After the reaction was completed, the room temperature was restored, and the product was filtered and collected. The product was washed with anhydrous ethanol and dried to obtain a modified carbonized material; 10g of 1-aminopropyl-3-methylimidazolium hexafluorophosphate was added to 500ml of deionized water, and the obtained solution was passed through an anion exchange resin to obtain a 1-aminopropyl-3-methylimidazolium hydroxide solution. A sample was taken and titrated with 0.1mol / L hydrochloric acid to calculate the required amount of lysine. Lysine was dissolved in an appropriate amount of deionized water and added to the 1-aminopropyl-3-methylimidazolium hydroxide solution. After stirring at room temperature for 24h, it was concentrated under reduced pressure to remove water and low-boiling substances, and then vacuum dried at 55℃ for 48h. Then, it was added to a mixed solvent composed of acetonitrile and methanol (volume ratio 9:1) with a solid-liquid mass ratio of 1:10 and stirred for 8h. Then, it was cooled at -5℃ to precipitate the unreacted lysine. After filtering, the filtrate was concentrated under reduced pressure and vacuum dried to obtain 1-aminopropyl-3-methylimidazolium lysine salt. 10 g of the modified carbonized material and 2.7 g of 1-aminopropyl-3-methylimidazolium tetrafluoroborate were added to 100 ml of anhydrous ethanol, and the mixture was heated to reflux for 24 h. After the reaction was completed, the mixture was returned to room temperature, filtered, and the product was collected and extracted with dichloromethane for 12 h, and then dried to obtain a carbonized material with immobilized ionic liquid; The solid-supported ionic liquid carbonized material was activated for 2 hours at a CO2 flow rate of 200 ml / min and a temperature of 700°C, and then vapor deposited. During vapor deposition, nitrogen was used as the carrier gas, benzene was used as the deposition gas, the vapor deposition temperature was 800°C, the vapor deposition time was 120 minutes, the carrier gas flow rate was 200 ml / min, the deposition gas flow rate was 0.5 ml / min, and the material was cooled to room temperature after vapor deposition.

[0022] Embodiment 3: A method for preparing a molecular sieve is as follows: In a nitrogen atmosphere, walnut shells with a particle size of 0.25-2 mm were heated to 550°C at a rate of 10°C / min and kept warm for 45 minutes. After returning to room temperature, they were crushed to less than 10 μm to obtain pre-carbonized powder. Pre-carbonized powder, 2124 phenolic resin powder, coal tar and polyethylene glycol 400 in a mass ratio of 1:0.2:0.15:0.05 were fully mixed and stirred in a kneader, and then extruded into pellets by a tablet press, which were heated to 1000°C at a speed of 10°C / min and carbonized for 2 hours to obtain a carbonized material; 10 g of carbonized material and 2 g of 3-chloropropyltrimethoxysilane were added to 100 ml of toluene, and heated to reflux for 24 h under nitrogen protection. After the reaction was completed, the room temperature was restored, and the product was filtered and collected. The product was washed with anhydrous ethanol and dried to obtain a modified carbonized material; 10g of 1-aminopropyl-3-methylimidazolium hexafluorophosphate was added to 500ml of deionized water, and the obtained solution was passed through an anion exchange resin to obtain a 1-aminopropyl-3-methylimidazolium hydroxide solution. A sample was taken and titrated with 0.1mol / L hydrochloric acid to calculate the required amount of lysine. Lysine was dissolved in an appropriate amount of deionized water and added to the 1-aminopropyl-3-methylimidazolium hydroxide solution. After stirring at room temperature for 24h, it was concentrated under reduced pressure to remove water and low-boiling substances, and then vacuum dried at 55℃ for 48h. Then, it was added to a mixed solvent composed of acetonitrile and methanol (volume ratio 9:1) with a solid-liquid mass ratio of 1:10 and stirred for 8h. Then, it was cooled at -5℃ to precipitate the unreacted lysine. After filtering, the filtrate was concentrated under reduced pressure and vacuum dried to obtain 1-aminopropyl-3-methylimidazolium lysine salt. 10 g of the modified carbonized material and 2.7 g of 1-aminopropyl-3-methylimidazolium tetrafluoroborate were added to 100 ml of anhydrous ethanol, and the mixture was heated to reflux for 24 h. After the reaction was completed, the mixture was returned to room temperature, filtered, and the product was collected and extracted with dichloromethane for 12 h, and then dried to obtain a carbonized material with immobilized ionic liquid; The solid-supported ionic liquid carbonized material was activated for 2 hours at a CO2 flow rate of 200 ml / min and a temperature of 700°C, and then vapor deposited. During vapor deposition, nitrogen was used as the carrier gas, benzene was used as the deposition gas, the vapor deposition temperature was 900°C, the vapor deposition time was 120 minutes, the carrier gas flow rate was 200 ml / min, the deposition gas flow rate was 0.5 ml / min, and the material was cooled to room temperature after vapor deposition.

[0023] Comparative Example 1: It is basically the same as Example 2, except that the carbonized material is directly activated.

[0024] A method for preparing a molecular sieve is as follows: In a nitrogen atmosphere, walnut shells with a particle size of 0.25-2 mm were heated to 550°C at a rate of 10°C / min and kept warm for 45 minutes. After returning to room temperature, they were crushed to less than 10 μm to obtain pre-carbonized powder. Pre-carbonized powder, 2124 phenolic resin powder, coal tar and polyethylene glycol 400 in a mass ratio of 1:0.2:0.15:0.05 were fully mixed and stirred in a kneader, and then extruded into pellets by a tablet press, which were heated to 1000°C at a speed of 10°C / min and carbonized for 2 hours to obtain a carbonized material; The carbonized material was activated for 2 hours at a CO2 flow rate of 200 ml / min and a temperature of 700°C, and then vapor deposited. During vapor deposition, nitrogen was used as the carrier gas, benzene was used as the deposition gas, the vapor deposition temperature was 800°C, the vapor deposition time was 120 minutes, the carrier gas flow rate was 200 ml / min, the deposition gas flow rate was 0.5 ml / min, and the material was cooled to room temperature after vapor deposition.

[0025] Comparative Example 2: The method is substantially the same as Example 2, except that 1-aminopropyl-3-methylimidazolium tetrafluoroborate is used instead of 1-aminopropyl-3-methylimidazolium lysine salt.

[0026] A method for preparing a molecular sieve is as follows: In a nitrogen atmosphere, walnut shells with a particle size of 0.25-2 mm were heated to 550°C at a rate of 10°C / min and kept warm for 45 minutes. After returning to room temperature, they were crushed to less than 10 μm to obtain pre-carbonized powder. Pre-carbonized powder, 2124 phenolic resin powder, coal tar and polyethylene glycol 400 in a mass ratio of 1:0.2:0.15:0.05 were fully mixed and stirred in a kneader, and then extruded into pellets by a tablet press, which were heated to 1000°C at a speed of 10°C / min and carbonized for 2 hours to obtain a carbonized material; 10 g of carbonized material and 2 g of 3-chloropropyltrimethoxysilane were added to 100 ml of toluene, and heated to reflux for 24 h under nitrogen protection. After the reaction was completed, the room temperature was restored, and the product was filtered and collected. The product was washed with anhydrous ethanol and dried to obtain a modified carbonized material; 10 g of the modified carbonized material and 2.7 g of 1-aminopropyl-3-methylimidazolium tetrafluoroborate were added to 100 ml of anhydrous ethanol, and the mixture was heated to reflux for 24 h. After the reaction was completed, the mixture was returned to room temperature, filtered, and the product was collected and extracted with dichloromethane for 12 h, and then dried to obtain a carbonized material with immobilized ionic liquid; The solid-supported ionic liquid carbonized material was activated for 2 hours at a CO2 flow rate of 200 ml / min and a temperature of 700°C, and then vapor deposited. During vapor deposition, nitrogen was used as the carrier gas, benzene was used as the deposition gas, the vapor deposition temperature was 800°C, the vapor deposition time was 120 minutes, the carrier gas flow rate was 200 ml / min, the deposition gas flow rate was 0.5 ml / min, and the material was cooled to room temperature after vapor deposition.

[0027] Comparative Example 3: The method is substantially the same as Example 2, except that 1-aminopropyl-3-methylimidazolium hexafluorophosphate is used instead of 1-aminopropyl-3-methylimidazolium lysine salt.

[0028] A method for preparing a molecular sieve is as follows: In a nitrogen atmosphere, walnut shells with a particle size of 0.25-2 mm were heated to 550°C at a rate of 10°C / min and kept warm for 45 minutes. After returning to room temperature, they were crushed to less than 10 μm to obtain pre-carbonized powder. Pre-carbonized powder, 2124 phenolic resin powder, coal tar and polyethylene glycol 400 in a mass ratio of 1:0.2:0.15:0.05 were fully mixed and stirred in a kneader, and then extruded into pellets by a tablet press, which were heated to 1000°C at a speed of 10°C / min and carbonized for 2 hours to obtain a carbonized material; 10 g of carbonized material and 2 g of 3-chloropropyltrimethoxysilane were added to 100 ml of toluene, and heated to reflux for 24 h under nitrogen protection. After the reaction was completed, the room temperature was restored, and the product was filtered and collected. The product was washed with anhydrous ethanol and dried to obtain a modified carbonized material; 10 g of the modified carbonized material and 2.7 g of 1-aminopropyl-3-methylimidazolium hexafluorophosphate were added to 100 ml of anhydrous ethanol, and the mixture was heated to reflux for 24 h. After the reaction was completed, the mixture was returned to room temperature, filtered, and the product was collected and extracted with dichloromethane for 12 h, and then dried to obtain a carbonized material with immobilized ionic liquid; The solid-supported ionic liquid carbonized material was activated for 2 hours at a CO2 flow rate of 200 ml / min and a temperature of 700°C, and then vapor deposited. During vapor deposition, nitrogen was used as the carrier gas, benzene was used as the deposition gas, the vapor deposition temperature was 800°C, the vapor deposition time was 120 minutes, the carrier gas flow rate was 200 ml / min, the deposition gas flow rate was 0.5 ml / min, and the material was cooled to room temperature after vapor deposition.

[0029] Comparative Example 4: The method is substantially the same as Example 2, except that 1-aminopropyl-3-methylimidazolium bromide is used instead of 1-aminopropyl-3-methylimidazolium lysine.

[0030] A method for preparing a molecular sieve is as follows: In a nitrogen atmosphere, walnut shells with a particle size of 0.25-2 mm were heated to 550°C at a rate of 10°C / min and kept warm for 45 minutes. After returning to room temperature, they were crushed to less than 10 μm to obtain pre-carbonized powder. Pre-carbonized powder, 2124 phenolic resin powder, coal tar and polyethylene glycol 400 in a mass ratio of 1:0.2:0.15:0.05 were fully mixed and stirred in a kneader, and then extruded into pellets by a tablet press, which were heated to 1000°C at a speed of 10°C / min and carbonized for 2 hours to obtain a carbonized material; 10 g of carbonized material and 2 g of 3-chloropropyltrimethoxysilane were added to 100 ml of toluene, and heated to reflux for 24 h under nitrogen protection. After the reaction was completed, the room temperature was restored, and the product was filtered and collected. The product was washed with anhydrous ethanol and dried to obtain a modified carbonized material; 10 g of the modified carbonized material and 2.7 g of 1-aminopropyl-3-methylimidazolium bromide were added to 100 ml of anhydrous ethanol, and the mixture was heated to reflux for 24 h. After the reaction was completed, the mixture was returned to room temperature, filtered, and the product was collected and extracted with dichloromethane for 12 h, and then dried to obtain a carbonized material with immobilized ionic liquid; The solid-supported ionic liquid carbonized material was activated for 2 hours at a CO2 flow rate of 200 ml / min and a temperature of 700°C, and then vapor deposited. During vapor deposition, nitrogen was used as the carrier gas, benzene was used as the deposition gas, the vapor deposition temperature was 800°C, the vapor deposition time was 120 minutes, the carrier gas flow rate was 200 ml / min, the deposition gas flow rate was 0.5 ml / min, and the material was cooled to room temperature after vapor deposition.

[0031] Performance Test: ① The specific surface area of ​​the molecular sieves prepared in Examples 1-3 and Comparative Examples 1-4 of the present invention was measured using an ASAP2400 static nitrogen adsorption instrument.

[0032] ② The CH4 / N2 mixed gas separation performance of the molecular sieves prepared in Examples 1-3 of the present invention and Comparative Examples 1-4 was evaluated and screened using an adsorption instrument. Under the conditions of 0.1 MPa and 298 K, the adsorption volumes of the molecular sieves for single components He, CH4 and N2 within 3 min were tested, thereby calculating the adsorption amounts of the molecular sieves for CH4 and N2, respectively, and obtaining the corresponding separation coefficients of the CH4 / N2 mixed gas, as shown in Formulas (1) and (2), respectively.

[0033] Q i = (1) S ads = (2) In the formula, Q i , Q j are the adsorption amounts of gas components i and j, mL / g, respectively; V i 、V j is the adsorption volume of gas components i and j, mL; V He is the adsorption volume of He, mL; K is the equilibrium coefficient at the corresponding test temperature; m is the mass of the tested molecular sieve, g; S ads is the separation factor of the mixed gas; p i、p j is the adsorption pressure, MPa, and the results are shown in Table 1 below: Table 1: As can be seen from Table 1 above, the molecular sieve prepared by the method of the present invention has a high specific surface area and exhibits excellent selective nitrogen adsorption performance in a methane-nitrogen mixed system; By comparing Examples 1-3, it can be seen that different vapor deposition temperatures have an impact on the specific surface area and methane-nitrogen separation performance of the prepared molecular sieve. When the vapor deposition temperature is 800° C., the performance of the prepared molecular sieve is optimal.

[0034] By comparing Example 2 with Comparative Example 1, it can be seen that the treatment with 3-chloropropyltrimethoxysilane and ionic liquid plays a positive role in improving the specific surface area of ​​the molecular sieve and the methane and nitrogen separation performance.

[0035] By comparing Example 2 with Comparative Examples 2-4, it can be seen that 1-aminopropyl-3-methylimidazolium lysine salt has a greater improvement in the specific surface area of ​​the molecular sieve and the methane and nitrogen separation performance than 1-aminopropyl-3-methylimidazolium bromide, 1-aminopropyl-3-methylimidazolium tetrafluoroborate, and 1-aminopropyl-3-methylimidazolium hexafluorophosphate.

[0036] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a molecular sieve, characterized in that: The details are as follows: In a nitrogen atmosphere, the biomass raw material is heated to 500-600°C and kept at this temperature for 30-60 minutes before being crushed to obtain a pre-carbonized powder; Pre-carbonized powder, phenolic resin powder, coal tar and polyethylene glycol are mixed and then extruded to obtain pellets, which are then heated to 800-1000° C. and carbonized for 1-3 hours to obtain carbonized material; Add the carbonized material and 3-chloropropyltrimethoxysilane into toluene, heat to reflux for reaction for 12-48 hours under nitrogen protection, return to room temperature after the reaction is completed, filter, collect the product, wash and dry to obtain the modified carbonized material; Add the modified carbonized material and the ionic liquid into anhydrous ethanol, heat to reflux for reaction for 12-48 hours, return to room temperature after the reaction is completed, filter, collect the product, extract with dichloromethane for 12-48 hours, and then dry to obtain the immobilized ionic liquid carbonized material; Activate the immobilized ionic liquid carbonized material at a CO2 flow rate of 100-500 ml / min and a temperature of 600-800°C for 1-3 hours; Then, vapor deposition is carried out, with nitrogen as carrier gas, the vapor deposition temperature is 700-900°C, the vapor deposition time is 90-120min, and the vapor deposition is cooled to room temperature after completion.

2. The method for preparing a molecular sieve according to claim 1, characterized in that: The biomass raw material is nut shells.

3. The method for preparing a molecular sieve according to claim 1, characterized in that: The mass ratio of the pre-carbonized powder, phenolic resin powder, coal tar and polyethylene glycol is 1:0.1-0.3:0.1-0.3:0.01-0.

1.

4. The method for preparing a molecular sieve according to claim 1, characterized in that: The mass ratio of the carbonized material to 3-chloropropyltrimethoxysilane is 1:0.1-0.

5.

5. The method for preparing a molecular sieve according to claim 1, characterized in that: The mass ratio of the modified carbonized material to the ionic liquid is 1:0.1-0.

5.

6. The method for preparing a molecular sieve according to claim 1, characterized in that: The ionic liquid is 1-aminopropyl-3-methylimidazolium lysine salt.

7. The method for preparing a molecular sieve according to claim 1, characterized in that: The deposition gas is any one of benzene, toluene and xylene or a mixture of two or more thereof.

8. The method for preparing a molecular sieve according to claim 7, characterized in that: The carrier gas flow rate is 100-500 ml / min, and the deposition gas flow rate is 0.1-1 ml / min.

9. A molecular sieve, characterized in that: The molecular sieve is prepared by the preparation method of any one of claims 1 to 8.

10. Use of the molecular sieve according to claim 9 in nitrogen separation.

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