Zeolite molecular sieve for adsorptive separation of carbon dioxide and its preparation method

Abstract

The present invention belongs to the technical field of carbon dioxide adsorption and separation materials, and specifically discloses a zeolite molecular sieve for adsorbing and separating carbon dioxide and a preparation method thereof. It is used to solve the problem of how to improve the adsorption selectivity of 5A zeolite molecular sieve for carbon dioxide. The method includes the following steps: adding 5-phosphonopentanoic acid or 4-aminobutylphosphonic acid into a carbon tetrachloride solvent, and then adding 5A zeolite molecular sieve and stirring, wherein the dosage ratio of the organic phosphonic acid to the 5A zeolite molecular sieve is 0.0053-0.53 mmol:1 g, and the dosage ratio of the carbon tetrachloride solvent to the 5A zeolite molecular sieve is 150-250 mL:1 g; then centrifuging to separate, removing the upper solution, then after heat treatment, cooling to room temperature, and washing with the carbon tetrachloride solvent for multiple times; finally, drying under vacuum to obtain the surface-modified 5A zeolite molecular sieve. The present invention is beneficial to improving the adsorption kinetic selectivity of carbon dioxide in propylene and propane gases.

Description

Technical Field

[0001] The present invention belongs to the technical field of carbon dioxide adsorption and separation materials, and particularly relates to a zeolite molecular sieve for adsorbing and separating carbon dioxide and a preparation method thereof. Background Art

[0002] The adsorption method is a simple method for capturing carbon dioxide (CO2), which can adsorb and separate CO2 in industrial gases (such as coke oven gas, blast furnace gas, coal chemical waste gas, refinery waste gas, etc.), convert low-value gas or waste gas into high-value resource gas, reduce CO2 emissions, and alleviate problems such as climate change and ocean acidification. Adsorption separation can be based on the equilibrium separation mechanism (the equilibrium adsorption amounts of different components in the adsorption material are different), the kinetic separation mechanism (the adsorption rates of different components are different), and the steric hindrance separation mechanism (based on the sieving effect of the pore openings of porous adsorption materials, molecules smaller than the pore opening size can enter, while molecules larger than the pore opening size cannot enter). Solid materials used for adsorbing and separating CO2 include zeolite molecular sieves, carbon molecular sieves, porous alumina, porous silica, metal-organic framework materials, covalent organic framework materials, hydrogen-bonded organic framework materials, etc. Among them, zeolite molecular sieves are inorganic silicon (aluminum / phosphorus) salts, which have high thermal stability, high hydrothermal stability, and molecular-scale pores, and are a type of adsorption material with low production cost, large CO2 adsorption capacity, and low adsorption operation energy consumption.

[0003] The molecular kinetic diameter of CO2 is smaller than that of the accompanying N2 molecules CH4 molecules C2H4 molecules C2H6 molecules C3H6 molecules C3H8 molecules etc. If zeolite molecular sieves are used to adsorb and separate CO2, the pore opening or pore size needs to be strictly regulated so that CO2 molecules can easily enter, while other molecules cannot enter.

[0004] 5A zeolite molecular sieve is a commonly used adsorption material, and its specific surface area can reach 700 m 2 / g, but its pore openings are too large, and both CO2 and the aforementioned hydrocarbon molecules can easily diffuse into it, so that CO2 cannot be effectively adsorbed and separated. The present invention focuses on the adsorption and separation of CO2 in propylene (C3H6) and propane (C3H8) products, uses 5A zeolite molecular sieve as the adsorption material, and adjusts the pore structure of 5A zeolite molecular sieve to improve the adsorption selectivity of CO2. Summary of the Invention

[0005] An object of the present invention is to provide a preparation method of a zeolite molecular sieve for adsorbing and separating carbon dioxide, which effectively solves the problem of how to improve the adsorption selectivity of 5A zeolite molecular sieve for carbon dioxide.

[0006] To solve the above technical problems, the technical solution adopted by the present invention is as follows:

[0007] A preparation method of a zeolite molecular sieve for adsorbing and separating carbon dioxide, comprising the following steps: S1. First, add an organic phosphonic acid having a carboxyl or amino tail functional group to a carbon tetrachloride solvent, and then add a 5A zeolite molecular sieve, and stir for 10-20 h.

[0008] The dosage ratio of the organic phosphonic acid to the 5A zeolite molecular sieve is 0.0053-0.53 mmol: 1 g, and the dosage ratio of the carbon tetrachloride solvent to the 5A zeolite molecular sieve is 150-250 mL: 1 g.

[0009] S2. Centrifugally separate, the rotation speed of the centrifuge is 10000-16000 r / min, the centrifugation time is 5-15 min, and after centrifugation is completed, the upper solution is removed.

[0010] S3. Heat-treat at 110-130 °C for 8-12 h, cool to room temperature, wash with a carbon tetrachloride solvent 3-5 times, and the dosage of the carbon tetrachloride solvent for each wash is 100-200 mL.

[0011] S4. Dry under vacuum in a vacuum drying oven to obtain a phosphonic acid-grafted 5A zeolite molecular sieve for adsorbing and separating carbon dioxide.

[0012] Further, in step S1, the organic phosphonic acid is 5-phosphonopentanoic acid or 4-aminobutylphosphonic acid.

[0013] Further, in step S1, the mass ratio of 5-phosphonopentanoic acid to the 5A zeolite molecular sieve is 0.0244: 1, the mass ratio of 4-aminobutylphosphonic acid to the 5A zeolite molecular sieve is 0.0036: 1, and the dosage ratio of the carbon tetrachloride solvent to the 5A zeolite molecular sieve is 200 mL: 1 g.

[0014] Further, in step S1, the stirring time is 15 h.

[0015] Further, in step S2, the rotation speed of the centrifuge is 12000 r / min, and the centrifugation time is 10 min.

[0016] Further, in step S3, the heat treatment temperature is 120 °C, and the heat treatment time is 10 h.

[0017] Further, in step S3, the number of washing times is 4 times, and the dosage of the carbon tetrachloride solvent for each wash is 150 mL.

[0018] Another object of the present invention is to provide a zeolite molecular sieve for adsorbing and separating carbon dioxide, which is prepared by using the preparation method described in the above embodiments.

[0019] Compared with the prior art, the beneficial technical effects of the present invention are as follows:

[0020] (1) On the outer surface of the 5A zeolite molecular sieve, 5-phosphonopentanoic acid or 4-aminobutylphosphonic acid is grafted by chemical grafting method, and hydrogen bonds are formed between carboxyl or amino functional groups to form a dense monolayer. The resistance of this monolayer to the diffusion of C3H6 and C3H8 molecules is much greater than that to CO2 molecules, thereby improving the adsorption kinetic selectivity of CO2.

[0021] (2) By adjusting the density of 5-phosphonopentanoic acid or 4-aminobutylphosphonic acid molecules grafted on the surface of the 5A zeolite molecular sieve, on the basis of retaining a high CO2 adsorption kinetic selectivity, the problem of slow CO2 adsorption due to the overly dense organic phosphonic acid layer is effectively solved, thereby improving the CO2 adsorption rate, that is, reducing the time required for CO2 adsorption to reach the saturated adsorption amount, while maintaining the material with a high CO2 adsorption kinetic selectivity.

[0022] (3) By using 5-phosphonopentanoic acid or 4-aminobutylphosphonic acid to modify the outer surface of the 5A zeolite molecular sieve, a relatively dense gas molecule diffusion resistance layer is added, which can significantly slow down the diffusion of C3H6 and C3H8 molecules. Although it also slows down the diffusion of CO2 molecules to a certain extent, the main cavities and main pores in the 5A zeolite molecular sieve crystal are relatively large, and the diffusion of CO2 molecules in the crystal is relatively fast. Therefore, as long as the organic phosphonic acid layer is not overly dense, the CO2 adsorption is relatively fast and can reach the saturated adsorption amount within a few minutes. In the present invention, the phosphonic acid head group of 5-phosphonopentanoic acid or 4-aminobutylphosphonic acid is covalently bonded to the surface of the 5A zeolite molecular sieve, with high stability, heat resistance, water resistance, and mechanical collision resistance. By changing the types of organic phosphonic acid tail functional groups, adjusting the dosage of grafted organic phosphonic acid, and the material preparation process conditions, the CO2 adsorption kinetic selectivity and adsorption rate can be continuously regulated within a certain range according to actual needs, providing solutions for the CO2 adsorption and separation requirements in various scenarios. Description of the Drawings

[0023] Figure 1 is a schematic structural diagram of a phosphonic acid organic ligand on the surface of a 5A zeolite molecular sieve.

[0024] Figure 2 is a schematic diagram of hydrogen bond formation between the tail functional groups of 5-phosphonopentanoic acid molecules on the surface of a 5A zeolite molecular sieve.

[0025] Figure 3 is a schematic diagram of hydrogen bond formation between 4-aminobutylphosphonic acid and the zeolite surface at the pore orifice of a 5A zeolite molecular sieve.

[0026] Figure 4X-ray diffraction patterns of unmodified (a), 5-phosphonopentanoic acid grafted (b), and 4-aminobutylphosphonic acid grafted (c) 5A zeolite molecular sieves.

[0027] Figure 5 Are the nitrogen adsorption isotherms of the 5A zeolite molecular sieves used in Examples 1 to 12 at liquid nitrogen temperature.

[0028] Figure 6 Is the graph showing the change of CO2 adsorption amount with time at 25 °C for the 5-phosphonopentanoic acid grafted 5A zeolite molecular sieve prepared in Example 1.

[0029] Figure 7 Is the graph showing the change of C3H6 adsorption amount with time at 25 °C for the 5-phosphonopentanoic acid grafted 5A zeolite molecular sieve prepared in Example 1.

[0030] Figure 8 Is the graph showing the change of CO2 / C3H6 adsorption selectivity with time at 25 °C for the 5-phosphonopentanoic acid grafted 5A zeolite molecular sieve prepared in Example 1.

[0031] Figure 9 Is the graph showing the change of CO2 / C3H6 adsorption selectivity with time at 25 °C for the unmodified 5A zeolite molecular sieve.

[0032] Figure 10 Is the graph showing the change of CO2 adsorption amount with time at 25 °C for the 4-aminobutylphosphonic acid grafted 5A zeolite molecular sieve prepared in Example 4.

[0033] Figure 11 Is the graph showing the change of C3H6 adsorption amount with time at 25 °C for the 4-aminobutylphosphonic acid grafted 5A zeolite molecular sieve prepared in Example 4.

[0034] Figure 12 Is the graph showing the change of CO2 / C3H6 adsorption selectivity with time at 25 °C for the 4-aminobutylphosphonic acid grafted 5A zeolite molecular sieve prepared in Example 4. Detailed implementation mode

[0035] Implementation mode 1: A preparation method of a zeolite molecular sieve for adsorptive separation of carbon dioxide, comprising the following steps:

[0036] S1. First, add an organic phosphonic acid with a carboxyl or amino terminal functional group to a carbon tetrachloride solvent, and then add a 5A zeolite molecular sieve, and stir for 10 - 20 h.

[0037] The dosage ratio of the organic phosphonic acid to the 5A zeolite molecular sieve is 0.0053 - 0.53 mmol:1 g, and the dosage ratio of the carbon tetrachloride solvent to the 5A zeolite molecular sieve is 150 - 250 mL:1 g.

[0038] In this embodiment, the organic phosphonic acid used is 5-phosphonopentanoic acid or 4-aminobutylphosphonic acid.

[0039] S2. Centrifugal separation is carried out at a centrifuge speed of 10,000 - 16,000 r / min for 5 - 15 min. After centrifugation is completed, the upper solution is removed.

[0040] S3. Heat treatment is carried out at 110 - 130 °C for 8 - 12 h, cooled to room temperature, and washed 3 - 5 times with carbon tetrachloride solvent. The amount of carbon tetrachloride solvent used for each wash is 100 - 200 mL.

[0041] S4. Dry under vacuum in a vacuum drying oven to obtain 5A zeolite molecular sieve grafted with 5-phosphonopentanoic acid or 4-aminobutylphosphonic acid for carbon dioxide adsorption separation.

[0042] The 5A zeolite molecular sieve grafted with 5-phosphonopentanoic acid or 4-aminobutylphosphonic acid prepared in Embodiment 1 is used for gas adsorption tests. The specific adsorption test method is as follows: The Sieverts method (volumetric method) of a high-pressure gas adsorption instrument is used to measure the change of the pressure (adsorption amount) of a single gas (CO2, C3H6, C3H8) with adsorption time at a certain temperature (25, 50, 100 °C) in a closed system, and then the change of the adsorption selectivity of CO2 / C3H6 and CO2 / C3H8 with time is calculated based on the ideal adsorbed solution theory model IAST.

[0043] The principle of this embodiment is: Using chemical grafting technology to graft organic phosphonic acid with carboxyl or amino tail functional groups on the outer surface of 5A zeolite molecular sieve. As Figure 1 shown, the organic phosphonic acid includes a head group (head phosphonic acid functional group), a spacer group (carbon chain), and a tail group (tail carboxyl or amino functional group). The head phosphonic acid functional group of the organic phosphonic acid is connected to the surface of the 5A zeolite molecular sieve (covalent bond). When the loading amount of the organic phosphonic acid is large, the organic phosphonic acid molecules stand upright, and hydrogen bonds are formed between the tail carboxyl or amino functional groups. As Figure 2 shown; when the loading amount of the organic phosphonic acid is low, hydrogen bonds are formed between the tail functional group and the hydroxyl group on the outer surface of the zeolite, showing a lying bridge structure. As Figure 3 shown. The organic phosphonic acid grafted on the outer surface of the 5A zeolite molecular sieve generates resistance to the diffusion and mass transfer of gas molecules. The small molecule CO2 is relatively easy to pass through, while the larger C3H6 and C3H8 molecules are more difficult to pass through, thereby improving the adsorption selectivity of CO2.

[0044] 5-Phosphonopentanoic acid or 4-aminobutylphosphonic acid is grafted onto the outer surface of 5A zeolite molecular sieve without changing the internal crystal structure of the 5A zeolite molecular sieve. The X-ray diffraction (Rigaku Smartlab type X-ray diffractometer in Japan, Cu target Kα ray, scanning step 0.01°, scanning speed 2° / min) of 5-phosphonopentanoic acid or 4-aminobutylphosphonic acid grafted and unmodified 5A zeolite molecular sieve is compared, as Figure 4 shown. After surface grafting, the diffraction peak angles and relative intensities of the 5A zeolite molecular sieve remain unchanged, that is, the crystal structure of the 5A zeolite molecular sieve is not changed.

[0045] The present invention will be further described in detail below in conjunction with specific embodiments.

[0046] Example 1: Take 0.0610 g of 5-phosphonopentanoic acid (CAS No. 5650-84-0, (HO)2PO(CH2)4COOH, purity 99%, the same below), add it to 200 mL of carbon tetrachloride solvent (CAS No. 56-23-5, purity 99%, the same below), and then add 1 g of 5A zeolite molecular sieve (<10 μm, Sigma-Aldrich 233676, the same below). The dosage of 5-phosphonopentanoic acid is 2 times the theoretical dosage for forming a complete monolayer on the outer surface of the 5A zeolite molecular sieve, and stir for 15 h. The nitrogen adsorption isotherm of the 5A zeolite molecular sieve at liquid nitrogen temperature is as Figure 5 shown (measured by ASAP 2460 type adsorption instrument of American Micromeritics Instrument Corporation). The specific surface area is obtained by plotting with the BET equation as 726 m 2 / g, and the external surface area is obtained by the t-Plot method as 30 m 2 / g.

[0047] Then, centrifuge at a speed of 12000 r / min for 10 min in a centrifuge to remove the upper solution; then heat-treat at 120 °C for 10 h and cool to room temperature, and wash 4 times with carbon tetrachloride solvent (150 mL each time); finally, dry in a vacuum drying oven under vacuum (100 Pa) for 6 h to obtain 5-phosphonopentanoic acid grafted 5A zeolite molecular sieve, and its X-ray diffraction is as Figure 4 (b) shown, which is the same as that of the unmodified 5A zeolite molecular sieve.

[0048] Take 100 mg of the 5-phosphonopentanoic acid grafted 5A zeolite molecular sieve prepared in this example. At 25 °C and an initial pressure of 20 kPa, the change of the adsorption amount of CO2 (purity 99.999%, the same below) with time is measured by a high-pressure gas adsorption instrument (PCT-Pro type, produced by Setaram Company in France), as Figure 6 shown. The CO2 adsorption reaches the saturated adsorption amount of 2.38 mmol / g in 12 min; the change of the adsorption amount of C3H6 (purity 99.5%, the same below) with time is asFigure 7 as shown; the change of the adsorption selectivity of CO2 / C3H6 with time is as Figure 8 shown, the maximum value of the adsorption kinetic selectivity of CO2 / C3H6 is 601; while the adsorption kinetic selectivity of CO2 / C3H6 of the 5A zeolite molecular sieve without surface modification remains at only about 1.3, as Figure 9 shown.

[0049] Example 2: The difference between the method for preparing the 5-phosphonopentanoic acid grafted 5A zeolite molecular sieve in this example and that in Example 1 is that: the amount of 5-phosphonopentanoic acid used is 0.0244 g, and its amount is 0.8 times the theoretical amount for forming a complete monolayer on the surface of the 5A zeolite molecular sieve.

[0050] Take 100 mg of the 5-phosphonopentanoic acid grafted 5A zeolite molecular sieve prepared in this example. At 25 °C and an initial pressure of 20 kPa, the change of the CO2 adsorption amount with time was measured by a high-pressure gas adsorption instrument. The CO2 adsorption reached the saturated adsorption amount of 2.41 mmol / g in 7 min. The maximum value of the adsorption kinetic selectivity of CO2 / C3H8 is 903, while the adsorption kinetic selectivity of CO2 / C3H8 of the 5A zeolite molecular sieve without surface modification remains at only about 1.6.

[0051] Example 3: The difference between the method for preparing the 5-phosphonopentanoic acid grafted 5A zeolite molecular sieve in this example and that in Example 1 is that: the amount of 5-phosphonopentanoic acid used is 0.0183 g, and its amount is 0.6 times the theoretical amount for forming a complete monolayer on the outer surface of the 5A zeolite molecular sieve.

[0052] Take 100 mg of the 5-phosphonopentanoic acid grafted 5A zeolite molecular sieve prepared in this example. At 100 °C and an initial pressure of 20 kPa, the change of the CO2 adsorption amount with time was measured by a high-pressure gas adsorption instrument. The CO2 adsorption reached the saturated adsorption amount of 1.43 mmol / g in 3 min. The maximum value of the adsorption kinetic selectivity of CO2 / C3H6 is 220.

[0053] Example 4: The difference between this example and Example 1 is that: 0.0726 g of 4-aminobutylphosphonic acid (CAS No. 35622-27-6, (HO)2PO(CH2)4NH2, purity 99%) was used to replace 5-phosphonopentanoic acid in Example 1 to prepare a 4-aminobutylphosphonic acid grafted 5A zeolite molecular sieve. The amount of 4-aminobutylphosphonic acid used is 2 times the theoretical amount for forming a complete monolayer on the outer surface of the 5A zeolite molecular sieve. The X-ray diffraction of the 4-aminobutylphosphonic acid grafted 5A zeolite molecular sieve is as Figure 4 (c) shown, which is the same as that of the unmodified 5A zeolite molecular sieve.

[0054] Take 100 mg of the 4-aminobutylphosphonic acid-grafted 5A zeolite molecular sieve prepared in this example. At 25 °C and an initial pressure of 20 kPa, the change in the CO2 adsorption amount with time was measured using a high-pressure gas adsorption instrument, as Figure 10 shown. The CO2 adsorption was slow, and the adsorption amount at 60 min was 0.42 mmol / g; the change in the C3H6 adsorption amount with time is as Figure 11 shown; the change in the CO2 / C3H6 adsorption selectivity with time is as Figure 12 shown. The maximum value of the CO2 / C3H6 adsorption kinetic selectivity was 38.

[0055] Example 5: The difference between this example and Example 1 is that 0.0290 g of 4-aminobutylphosphonic acid was used instead of 5-phosphonopentanoic acid in Example 1 to prepare a 4-aminobutylphosphonic acid-grafted 5A zeolite molecular sieve. The amount of 4-aminobutylphosphonic acid used was 0.8 times the theoretical amount required to form a complete monolayer on the outer surface of the 5A zeolite molecular sieve.

[0056] Take 100 mg of the 4-aminobutylphosphonic acid-grafted 5A zeolite molecular sieve prepared in this example. At 25 °C and an initial pressure of 20 kPa, the change in the CO2 adsorption amount with time was measured using a high-pressure gas adsorption instrument. The CO2 adsorption was slow, and the adsorption amount at 60 min was 0.51 mmol / g; the maximum value of the CO2 / C3H6 adsorption kinetic selectivity was 54.

[0057] Example 6: The difference between this example and Example 1 is that 0.0036 g of 4-aminobutylphosphonic acid was used instead of 5-phosphonopentanoic acid in Example 1 to prepare a 4-aminobutylphosphonic acid-grafted 5A zeolite molecular sieve. The amount of 4-aminobutylphosphonic acid used was 0.1 times the theoretical amount required to form a complete monolayer on the outer surface of the 5A zeolite molecular sieve.

[0058] Take 100 mg of the 4-aminobutylphosphonic acid-grafted 5A zeolite molecular sieve prepared in this example. At 25 °C and an initial pressure of 20 kPa, the change in the CO2 adsorption amount with time was measured using a high-pressure gas adsorption instrument. The CO2 adsorption reached the saturated adsorption amount of 2.43 mmol / g in 10 min; the maximum value of the CO2 / C3H6 adsorption kinetic selectivity was 95.

[0059] Example 7: 0.0036 g of 4-aminobutylphosphonic acid was added to 150 mL of carbon tetrachloride solvent (the amount of 4-aminobutylphosphonic acid was 0.1 times the theoretical amount for forming a complete monolayer on the outer surface of 5A zeolite molecular sieve), and then 1 g of 5A zeolite molecular sieve was added and stirred for 10 h; then it was centrifuged at 10000 r / min for 15 min in a centrifuge to remove the upper solution; after heat treatment at 110 °C for 12 h and then cooled to room temperature, it was washed 3 times with carbon tetrachloride solvent (200 mL each time); finally, it was dried in a vacuum drying oven under vacuum (100 Pa) for 6 h to obtain 5A zeolite molecular sieve grafted with 4-aminobutylphosphonic acid.

[0060] 100 mg of the 5A zeolite molecular sieve grafted with 4-aminobutylphosphonic acid prepared in this example was taken, and at 50 °C and an initial pressure of 20 kPa, the change of CO2 adsorption amount with time was measured by a high-pressure gas adsorption instrument. The saturated adsorption amount of CO2 reached 2.01 mmol / g after 8 min of CO2 adsorption; the maximum value of the adsorption kinetic selectivity of CO2 / C3H6 was 43.

[0061] Example 8: 0.0036 g of 4-aminobutylphosphonic acid was added to 250 mL of carbon tetrachloride solvent (the amount of 4-aminobutylphosphonic acid was 0.1 times the theoretical amount for forming a complete monolayer on the outer surface of 5A zeolite molecular sieve), and then 1 g of 5A zeolite molecular sieve was added and stirred for 20 h; then it was centrifuged at 16000 r / min for 5 min in a centrifuge to remove the upper solution; after heat treatment at 130 °C for 8 h and then cooled to room temperature, it was washed 5 times with carbon tetrachloride solvent (100 mL each time); finally, it was dried in a vacuum drying oven under vacuum (100 Pa) for 6 h to obtain 5A zeolite molecular sieve grafted with 4-aminobutylphosphonic acid.

[0062] 100 mg of the 5A zeolite molecular sieve grafted with 4-aminobutylphosphonic acid prepared in this example was taken, and at 100 °C and an initial pressure of 20 kPa, the change of CO2 adsorption amount with time was measured by a high-pressure gas adsorption instrument. The saturated adsorption amount of CO2 reached 1.40 mmol / g after 6 min of CO2 adsorption; the maximum value of the adsorption kinetic selectivity of CO2 / C3H6 was 26.

[0063] Example 9: The difference between this example and Example 1 is that 0.0007 g of 4-aminobutylphosphonic acid was used to replace 5-phosphonopentanoic acid in Example 1 to obtain 5A zeolite molecular sieve grafted with 4-aminobutylphosphonic acid. The amount of 4-aminobutylphosphonic acid was 0.02 times the theoretical amount for forming a complete monolayer on the outer surface of 5A zeolite molecular sieve.

[0064] Take 100 mg of the 4-aminobutylphosphonic acid-grafted 5A zeolite molecular sieve prepared in this example. At 25 °C and an initial pressure of 20 kPa, the high-pressure gas adsorption instrument was used to measure the change in the CO2 adsorption amount over time. The CO2 adsorption reached the saturated adsorption amount of 2.45 mmol / g in 4 min; the maximum adsorption kinetic selectivity of CO2 / C3H6 was 3.7.

[0065] Example 10: The difference between this example and Example 1 is that 0.0015 g of 4-aminobutylphosphonic acid was used to replace 5-phosphonopentanoic acid in Example 1 to prepare a 4-aminobutylphosphonic acid-grafted 5A zeolite molecular sieve. The amount of 4-aminobutylphosphonic acid used was 0.04 times the theoretical amount for forming a complete monolayer on the outer surface of the 5A zeolite molecular sieve.

[0066] Take 100 mg of the 4-aminobutylphosphonic acid-grafted 5A zeolite molecular sieve prepared in this example. At 25 °C and an initial pressure of 20 kPa, the high-pressure gas adsorption instrument was used to measure the change in the CO2 adsorption amount over time. The CO2 adsorption reached the saturated adsorption amount of 2.42 mmol / g in 5 min; the maximum adsorption kinetic selectivity of CO2 / C3H6 was 8.6.

[0067] Example 11: The difference between this example and Example 1 is that 0.0073 g of 4-aminobutylphosphonic acid was used to replace 5-phosphonopentanoic acid in Example 1 to prepare a 4-aminobutylphosphonic acid-grafted 5A zeolite molecular sieve. The amount of 4-aminobutylphosphonic acid used was 0.2 times the theoretical amount for forming a complete monolayer on the outer surface of the 5A zeolite molecular sieve.

[0068] Take 100 mg of the 4-aminobutylphosphonic acid-grafted 5A zeolite molecular sieve prepared in this example. At 25 °C and an initial pressure of 20 kPa, the high-pressure gas adsorption instrument was used to measure the change in the CO2 adsorption amount over time. The CO2 adsorption reached the saturated adsorption amount of 2.40 mmol / g in 20 min; the maximum adsorption kinetic selectivity of CO2 / C3H6 was 317.

[0069] Example 12: The difference between this example and Example 1 is that 0.0022 g of 4-aminobutylphosphonic acid was used to replace 5-phosphonopentanoic acid in Example 1 to prepare a 4-aminobutylphosphonic acid-grafted 5A zeolite molecular sieve. The amount of 4-aminobutylphosphonic acid used was 0.06 times the theoretical amount for forming a complete monolayer on the outer surface of the 5A zeolite molecular sieve.

[0070] Take 100 mg of the 4-aminobutylphosphonic acid-grafted 5A zeolite molecular sieve prepared in this example. At 25 °C and an initial pressure of 20 kPa, the high-pressure gas adsorption instrument was used to measure the change in the CO2 adsorption amount with time. The CO2 adsorption reached the saturated adsorption amount of 2.42 mmol / g in 5 min; the maximum adsorption kinetic selectivity of CO2 / C3H8 was 49.

[0071] As can be seen from Examples 1 to 12, by modifying the surface of the 5A zeolite molecular sieve with 5-phosphonopentanoic acid or 4-aminobutylphosphonic acid, and by adjusting the dosage of the organic phosphonic acid and the material preparation process conditions, the adsorption kinetic selectivity of CO2 / C3H6 and CO2 / C3H8 of the modified 5A zeolite molecular sieve, as well as the speed of CO2 adsorption, can be regulated, so that it has a high adsorption kinetic selectivity and a fast CO2 adsorption speed at the same time.

[0072] The preferred process conditions for preparing the 5-phosphonopentanoic acid or 4-aminobutylphosphonic acid-modified 5A zeolite molecular sieve with high adsorption kinetic selectivity for CO2 / C3H6 and CO2 / C3H8 and fast CO2 adsorption speed are as follows: the mass ratio of 4-aminobutylphosphonic acid to 5A zeolite molecular sieve is 0.0036:1, the mass ratio of 5-phosphonopentanoic acid to 5A zeolite molecular sieve is 0.0244:1, the ratio of carbon tetrachloride solvent to 5A zeolite molecular sieve is 200 mL:1 g, the stirring time is 15 h, the centrifugation speed is 12,000 r / min, the centrifugation time is 10 min, the heat treatment temperature is 120 °C, the heat treatment time is 10 h, and it is washed 4 times with carbon tetrachloride solvent, with 150 mL of carbon tetrachloride solvent used for each wash.

[0073] Of course, the above description is not a limitation of the present invention, and the present invention is not limited to the above examples. Changes, modifications, additions or substitutions made by those skilled in the art within the essence of the present invention should also fall within the protection scope of the present invention.

Claims

1. A preparation method of a zeolite molecular sieve for adsorptive separation of carbon dioxide, characterized in that, It includes the following steps: S1. First, add an organic phosphonic acid with a carboxyl or amino terminal functional group into a carbon tetrachloride solvent, then add 5A zeolite molecular sieve, and stir for 10 - 20 h; The dosage ratio of the organic phosphonic acid to the 5A zeolite molecular sieve is 0.0053 - 0.53 mmol:1 g, and the dosage ratio of the carbon tetrachloride solvent to the 5A zeolite molecular sieve is 150 - 250 mL:1 g; S2. Centrifuge, with the centrifuge speed being 10000 - 16000 r / min and the centrifugation duration being 5 - 15 min. After centrifugation is completed, remove the upper solution; S3. Conduct heat treatment at 110 - 130 °C for 8 - 12 h, cool to room temperature, wash with the carbon tetrachloride solvent for 3 - 5 times, and the dosage of the carbon tetrachloride solvent for each wash is 100 - 200 mL; S4. Dry under vacuum in a vacuum drying oven to obtain a phosphonic acid grafted 5A zeolite molecular sieve for adsorptive separation of carbon dioxide; In step S1, the organic phosphonic acid is 5-phosphonopentanoic acid or 4-aminobutylphosphonic acid; In step S1, the mass ratio of 5-phosphonopentanoic acid to the 5A zeolite molecular sieve is 0.0244:1, the mass ratio of 4-aminobutylphosphonic acid to the 5A zeolite molecular sieve is 0.0036:1, and the dosage ratio of the carbon tetrachloride solvent to the 5A zeolite molecular sieve is 200 mL:1 g; By grafting 5-phosphonopentanoic acid or 4-aminobutylphosphonic acid on the outer surface of the 5A zeolite molecular sieve using the chemical grafting method, hydrogen bonds are formed between the carboxyl or amino functional groups to form a dense monolayer. The resistance of the monolayer to the diffusion of C3H6 and C3H8 molecules is greater than that to CO2 molecules, thereby improving the adsorption kinetic selectivity of CO2; By modulating the density of the 5-phosphonopentanoic acid or 4-aminobutylphosphonic acid molecules grafted on the surface of the 5A zeolite molecular sieve, the adsorption rate of CO2 is increased on the basis of retaining the adsorption kinetic selectivity of CO2.

2. The preparation method of the zeolite molecular sieve for adsorptive separation of carbon dioxide according to claim 1, characterized in that, In step S1, the stirring duration is 15 h.

3. The preparation method of the zeolite molecular sieve for adsorbing and separating carbon dioxide according to claim 2, characterized in that, In step S2, the centrifuge speed is 12000 r / min and the centrifugation duration is 10 min.

4. The preparation method of the zeolite molecular sieve for adsorptive separation of carbon dioxide according to claim 3, wherein, In step S3, the heat treatment temperature is 120 °C and the heat treatment duration is 10 h.

5. The preparation method of the zeolite molecular sieve for adsorptive separation of carbon dioxide according to claim 4, wherein, In step S3, the number of washing times is 4 times, and the dosage of the carbon tetrachloride solvent for each wash is 150 mL.

6. A zeolite molecular sieve for adsorptive separation of carbon dioxide, characterized in that, Prepared by using the preparation method described in any one of claims 1 - 5.

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