Zeolite molecular sieve for adsorbing and separating carbon dioxide and preparation method thereof

Abstract

The invention belongs to the technical field of carbon dioxide adsorption separation materials, and particularly discloses a zeolite molecular sieve for adsorbing and separating carbon dioxide and a preparation method thereof. The method is used for solving the problem of how to improve the adsorption selectivity of the 5A zeolite molecular sieve on carbon dioxide. Comprising the following steps: adding 5-phosphonovaleric acid or 4-aminobutylphosphonic acid into a carbon tetrachloride solvent, then adding a 5A zeolite molecular sieve, and stirring, with the ratio of the organic phosphonic acid to the 5A zeolite molecular sieve being 0.0053-0.53 mmol: 1 g and the ratio of the carbon tetrachloride solvent to the 5A zeolite molecular sieve being 150-250 mL: 1 g; carrying out centrifugal separation, removing an upper solution, carrying out heat treatment, cooling to room temperature, and washing with a carbon tetrachloride solvent for multiple times; and finally, carrying out vacuum drying to prepare the surface modified 5A zeolite molecular sieve. The method is beneficial to improving the adsorption kinetic selectivity of carbon dioxide in propylene and propane gas.

Description

Technical Field

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

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

[0003] The molecular dynamics diameter of CO2 is Smaller than the N2 molecule that accompanies it CH4 molecule C2H4 molecule C2H6 molecule C3H6 molecule C3H8 molecule If zeolite molecular sieve is used to adsorb and separate CO2, the pore size or pore size must be strictly controlled to make it easy for CO2 molecules to enter while other molecules are difficult to enter.

[0004] 5A zeolite molecular sieve is a commonly used adsorption material with a specific surface area of ​​up to 700m 2 / g, but its pores are too large, CO2 and the aforementioned hydrocarbon molecules can easily diffuse into it, and 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, using 5A zeolite molecular sieve as the adsorption material, and adjusting the pore structure of 5A zeolite molecular sieve to improve the adsorption selectivity of CO2. Summary of the invention

[0005] One object of the present invention is to provide a method for preparing a zeolite molecular sieve for adsorption and separation of carbon dioxide, so as to effectively solve the problem of how to improve the adsorption selectivity of 5A zeolite molecular sieve for carbon dioxide.

[0006] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0007] A method for preparing a zeolite molecular sieve for adsorbing and separating carbon dioxide comprises the following steps: S1, firstly adding an organic phosphonic acid having a carboxyl or amino tail functional group into a carbon tetrachloride solvent, then adding a 5A zeolite molecular sieve, and stirring for 10 to 20 hours.

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

[0009] S2. Centrifugal separation, the centrifuge speed is 10000-16000r / min, the centrifugal time is 5-15min, and after the centrifugation is completed, the upper solution is removed.

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

[0011] S4. Drying under vacuum in a vacuum drying oven to obtain a phosphonic acid grafted 5A zeolite molecular sieve for adsorption and separation of carbon dioxide.

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

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

[0014] Furthermore, in step S1, the stirring time is 15 hours.

[0015] Furthermore, in step S2, the centrifuge speed 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 washing times are 4 times, and the amount of carbon tetrachloride solvent used in each washing is 150 mL.

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

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

[0020] (1) The present invention uses a chemical grafting method to graft 5-phosphonovaleric acid or 4-aminobutylphosphonic acid on the outer surface of 5A zeolite molecular sieve, and hydrogen bonds are formed between the 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 the resistance to CO2 molecules, thereby improving the adsorption kinetic selectivity of CO2.

[0021] (2) The present invention adjusts the density of 5-phosphonovaleric acid or 4-aminobutylphosphonic acid molecules grafted on the surface of 5A zeolite molecular sieve to effectively solve the problem of slow CO2 adsorption due to the overly dense organic phosphonic acid layer while retaining a relatively high CO2 adsorption kinetic selectivity, thereby increasing the CO2 adsorption rate, that is, reducing the time required for CO2 adsorption to reach the saturated adsorption amount, while maintaining the material's relatively high CO2 adsorption kinetic selectivity.

[0022] (3) The present invention modifies the outer surface of 5A zeolite molecular sieve by selecting 5-phosphonovaleric acid or 4-aminobutylphosphonic acid to add a denser gas molecule diffusion resistance layer, 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 crystal cavity and main crystal pore in the 5A zeolite molecular sieve crystal are relatively large, and the CO2 molecules diffuse faster in the crystal. Therefore, as long as the organic phosphonic acid layer is not too dense, CO2 adsorption is relatively fast, and the saturated adsorption amount can be reached within a few minutes. The phosphonic acid head group of 5-phosphonovaleric acid or 4-aminobutylphosphonic acid of the present invention is connected to the surface of 5A zeolite molecular sieve by covalent bonds, has high stability, and is heat-resistant, water-resistant, and mechanically resistant. By changing the type of organic phosphonic acid tail functional group, adjusting the amount 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, and can provide solutions for CO2 adsorption and separation needs in various scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0024] Figure 2 It is a schematic diagram of the hydrogen bonds formed between the tail functional groups of 5-phosphonovaleric acid molecules on the surface of 5A zeolite molecular sieve.

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

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

[0027] Figure 5 It is the nitrogen adsorption isotherm of the 5A zeolite molecular sieve used in Examples 1 to 12 at liquid nitrogen temperature.

[0028] Figure 6 This is a graph showing the change in the amount of CO2 adsorbed by the 5A zeolite molecular sieve grafted with 5-phosphonovaleric acid prepared in Example 1 at 25°C over time.

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

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

[0031] Fig. 9 This is a graph showing the change in the adsorption selectivity of CO2 / C3H6 over time for unmodified 5A zeolite molecular sieve at 25°C.

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

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

[0034] Fig.12 This is a graph showing the change in the adsorption selectivity of CO2 / C3H6 over time at 25°C for the 5A zeolite molecular sieve grafted with 4-aminobutylphosphonic acid prepared in Example 4. DETAILED DESCRIPTION

[0035] Embodiment 1: A method for preparing a zeolite molecular sieve for adsorption and separation of carbon dioxide, comprising the following steps:

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

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

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

[0039] S2. Centrifugal separation, the centrifuge speed is 10000-16000r / min, the centrifugal time is 5-15min, and after the centrifugation is completed, the upper solution is removed.

[0040] S3, heat treatment at 110-130°C for 8-12h, cooling to room temperature, washing with carbon tetrachloride solvent for 3-5 times, with the amount of carbon tetrachloride solvent used for each washing being 100-200mL;

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

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

[0043] The principle of this embodiment is to graft an organic phosphonic acid having a carboxyl or amino tail functional group on the outer surface of 5A zeolite molecular sieve using chemical grafting technology, such as Figure 1 As 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 organic phosphonic acid loading is large, the organic phosphonic acid molecule is in a standing state, and hydrogen bonds are formed between the tail carboxyl or amino functional groups, such as Figure 2 As shown; when the loading amount of 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, presenting a flat bridge structure, such as Figure 3 As shown in the figure, the organic phosphonic acid grafted on the outer surface of 5A zeolite molecular sieve creates resistance to the diffusion and mass transfer of gas molecules, making it easier for small molecules of CO2 to pass through, while larger molecules of C3H6 and C3H8 are more difficult to pass through, thereby improving the adsorption selectivity of CO2.

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

[0045] The present invention is further described in detail below with reference to specific embodiments.

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

[0047] Then, the mixture was centrifuged at 12000 r / min for 10 min in a centrifuge to remove the upper solution; after heat treatment at 120°C for 10 h, the mixture was cooled to room temperature and washed with carbon tetrachloride solvent 4 times (150 mL each time); finally, the mixture was dried in a vacuum oven under vacuum (100 Pa) for 6 h to obtain 5A zeolite molecular sieve grafted with 5-phosphonovaleric acid, and its X-ray diffraction was as follows: Figure 4 (b) is the same as that of unmodified 5A zeolite molecular sieve.

[0048] 100 mg of the 5A zeolite molecular sieve grafted with 5-phosphonovaleric acid prepared in this example was taken and the adsorption amount of CO2 (purity 99.999%, the same below) was measured with a high pressure gas adsorption instrument (PCT-Pro, produced by Sethram, France) at 25°C and an initial pressure of 20 kPa to obtain the change in the adsorption amount of CO2 (purity 99.999%, the same below). Figure 6 As shown in the figure, CO2 adsorption reaches saturation adsorption capacity of 2.38mmol / g after 12min; the adsorption capacity of C3H6 (purity 99.5%, the same below) changes with time as shown in the figure Figure 7 As shown; the adsorption selectivity of CO2 / C3H6 changes with time, such as Figure 8 As shown in Figure 2, the maximum adsorption kinetic selectivity of CO2 / C3H6 is 601; while the adsorption kinetic selectivity of CO2 / C3H6 of 5A zeolite molecular sieve without surface modification is maintained at only about 1.3, as shown in Figure 2. Fig. 9 shown.

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

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

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

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

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

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

[0055] Example 5: This example is different from Example 1 in that 0.0290 g of 4-aminobutylphosphonic acid is used to replace the 5-phosphonovaleric acid in Example 1 to prepare a 5A zeolite molecular sieve grafted with 4-aminobutylphosphonic acid. The amount of 4-aminobutylphosphonic acid used is 0.8 times the theoretical amount required to form a complete monolayer on the outer surface of the 5A zeolite molecular sieve.

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

[0057] Example 6: This example is different from Example 1 in that 0.0036 g of 4-aminobutylphosphonic acid is used to replace the 5-phosphonovaleric acid in Example 1 to prepare a 5A zeolite molecular sieve grafted with 4-aminobutylphosphonic acid. The amount of 4-aminobutylphosphonic acid used is 0.1 times the theoretical amount required to form a complete monolayer on the outer surface of the 5A zeolite molecular sieve.

[0058] 100 mg of 5A zeolite molecular sieve grafted with 4-aminobutylphosphonic acid prepared in this example was taken, and the change of CO2 adsorption amount over time was measured by high-pressure gas adsorption instrument at 25°C and initial pressure of 20 kPa. The CO2 adsorption reached a saturated adsorption amount of 2.43 mmol / g after 10 minutes; the maximum adsorption kinetic selectivity of CO2 / C3H6 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 centrifuged at 10000 r / min in a centrifuge for 15 min to remove the upper solution; then heat treated at 110° C. for 12 h and then cooled to room temperature, washed with carbon tetrachloride solvent 3 times (200 mL each time); finally 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 5A zeolite molecular sieve grafted with 4-aminobutylphosphonic acid prepared in this example was taken, and the change of CO2 adsorption amount over time was measured by high-pressure gas adsorption instrument at 50°C and initial pressure of 20 kPa. The CO2 adsorption reached a saturated adsorption amount of 2.01 mmol / g after 8 minutes; the maximum 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 centrifuged at 16000 r / min in a centrifuge for 5 min to remove the upper solution; then heat treated at 130° C. for 8 h and then cooled to room temperature, washed with carbon tetrachloride solvent 5 times (100 mL each time); finally 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 5A zeolite molecular sieve grafted with 4-aminobutylphosphonic acid prepared in this example was taken, and the change of CO2 adsorption amount over time was measured by a high-pressure gas adsorption instrument at 100°C and an initial pressure of 20 kPa. The CO2 adsorption reached a saturated adsorption amount of 1.40 mmol / g after 6 minutes; the maximum adsorption kinetic selectivity of CO2 / C3H6 was 26.

[0063] Example 9: This example is different from Example 1 in that 0.0007 g of 4-aminobutylphosphonic acid is used to replace the 5-phosphonovaleric acid in Example 1 to prepare a 5A zeolite molecular sieve grafted with 4-aminobutylphosphonic acid. The amount of 4-aminobutylphosphonic acid used is 0.02 times the theoretical amount required to form a complete monolayer on the outer surface of the 5A zeolite molecular sieve.

[0064] 100 mg of 5A zeolite molecular sieve grafted with 4-aminobutylphosphonic acid prepared in this example was taken, and the change of CO2 adsorption amount over time was measured by high-pressure gas adsorption instrument at 25°C and initial pressure of 20 kPa. The CO2 adsorption reached a saturated adsorption amount of 2.45 mmol / g after 4 minutes; the maximum adsorption kinetic selectivity of CO2 / C3H6 was 3.7.

[0065] Example 10: This example is different from Example 1 in that 0.0015 g of 4-aminobutylphosphonic acid is used to replace the 5-phosphonovaleric acid in Example 1 to prepare a 5A zeolite molecular sieve grafted with 4-aminobutylphosphonic acid. The amount of 4-aminobutylphosphonic acid used is 0.04 times the theoretical amount required to form a complete monolayer on the outer surface of the 5A zeolite molecular sieve.

[0066] 100 mg of 5A zeolite molecular sieve grafted with 4-aminobutylphosphonic acid prepared in this example was taken, and the change of CO2 adsorption amount over time was measured by high-pressure gas adsorption instrument at 25°C and initial pressure of 20 kPa. The CO2 adsorption reached a saturated adsorption amount of 2.42 mmol / g after 5 minutes; the maximum adsorption kinetic selectivity of CO2 / C3H6 was 8.6.

[0067] Example 11: This example is different from Example 1 in that 0.0073 g of 4-aminobutylphosphonic acid is used to replace the 5-phosphonovaleric acid in Example 1 to prepare a 5A zeolite molecular sieve grafted with 4-aminobutylphosphonic acid. The amount of 4-aminobutylphosphonic acid used is 0.2 times the theoretical amount required to form a complete monolayer on the outer surface of the 5A zeolite molecular sieve.

[0068] 100 mg of 5A zeolite molecular sieve grafted with 4-aminobutylphosphonic acid prepared in this example was taken, and the change of CO2 adsorption amount over time was measured by high-pressure gas adsorption instrument at 25°C and initial pressure of 20 kPa. The CO2 adsorption reached a saturated adsorption amount of 2.40 mmol / g after 20 minutes; the maximum adsorption kinetic selectivity of CO2 / C3H6 was 317.

[0069] Example 12: This example is different from Example 1 in that 0.0022 g of 4-aminobutylphosphonic acid is used to replace the 5-phosphonovaleric acid in Example 1 to prepare a 5A zeolite molecular sieve grafted with 4-aminobutylphosphonic acid. The amount of 4-aminobutylphosphonic acid used is 0.06 times the theoretical amount required to form a complete monolayer on the outer surface of the 5A zeolite molecular sieve.

[0070] 100 mg of 5A zeolite molecular sieve grafted with 4-aminobutylphosphonic acid prepared in this example was taken, and the change of CO2 adsorption amount over time was measured by high-pressure gas adsorption instrument at 25°C and initial pressure of 20 kPa. The CO2 adsorption reached a saturated adsorption amount of 2.42 mmol / g after 5 minutes; the maximum adsorption kinetic selectivity of CO2 / C3H8 was 49.

[0071] It can be seen from Examples 1 to 12 that by modifying the surface of 5A zeolite molecular sieve with 5-phosphonovaleric acid or 4-aminobutylphosphonic acid and adjusting the dosage of 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 higher adsorption kinetic selectivity and faster CO2 adsorption rate.

[0072] The preferred process conditions for preparing 5A zeolite molecular sieve modified with 5-phosphonovaleric acid or 4-aminobutylphosphonic acid having high CO2 / C3H6 and CO2 / C3H8 adsorption kinetics selectivity and fast CO2 adsorption rate are as follows: the mass ratio of 4-aminobutylphosphonic acid to 5A zeolite molecular sieve is 0.0036:1, the mass ratio of 5-phosphonovaleric acid to 5A zeolite molecular sieve is 0.0244:1, the ratio of carbon tetrachloride solvent to 5A zeolite molecular sieve is 200mL:1g, the stirring time is 15h, the centrifugal separation speed is 12000r / min, the centrifugal separation time is 10min, the heat treatment temperature is 120°C, the heat treatment time is 10h, and the mixture is washed with carbon tetrachloride solvent 4 times, with 150mL 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 technicians in this technical field within the essential scope of the present invention should also fall within the protection scope of the present invention.

Claims

1. A method for preparing a zeolite molecular sieve for adsorption and separation of carbon dioxide, characterized in that: The following steps are involved: S1. First, add an organic phosphonic acid having a carboxyl or amino tail functional group into a carbon tetrachloride solvent, then add 5A zeolite molecular sieve, and stir for 10 to 20 hours; The ratio of the amount of the organic phosphonic acid to the amount of the 5A zeolite molecular sieve is 0.0053-0.53 mmol:1 g, and the ratio of the amount of the carbon tetrachloride solvent to the amount of the 5A zeolite molecular sieve is 150-250 mL:1 g; S2, centrifugal separation, the centrifuge speed is 10000~16000r / min, the centrifugal time is 5~15min, after the centrifugation is completed, the upper solution is removed; S3, heat treatment at 110-130°C for 8-12h, cooling to room temperature, washing with carbon tetrachloride solvent for 3-5 times, with the amount of carbon tetrachloride solvent used for each washing being 100-200mL; S4. Drying under vacuum in a vacuum drying oven to obtain a phosphonic acid grafted 5A zeolite molecular sieve for adsorption and separation of carbon dioxide.

2. The method for preparing a zeolite molecular sieve for adsorption and separation of carbon dioxide according to claim 1, characterized in that: In step S1, the organic phosphonic acid is 5-phosphonopentanoic acid or 4-aminobutylphosphonic acid.

3. The method for preparing a zeolite molecular sieve for adsorption and separation of carbon dioxide according to claim 2, characterized in that: In step S1, the mass ratio of 5-phosphonovaleric acid to 5A zeolite molecular sieve is 0.0244:1, the mass ratio of 4-aminobutylphosphonic acid to 5A zeolite molecular sieve is 0.0036:1, and the amount ratio of carbon tetrachloride solvent to 5A zeolite molecular sieve is 200 mL:1 g.

4. The method for preparing a zeolite molecular sieve for adsorption and separation of carbon dioxide according to claim 3, characterized in that: In step S1, the stirring time is 15 hours.

5. The method for preparing a zeolite molecular sieve for adsorption and separation of carbon dioxide according to claim 4, characterized in that: In step S2, the centrifuge speed is 12000 r / min, and the centrifugation time is 10 min.

6. The method for preparing a zeolite molecular sieve for adsorption and separation of carbon dioxide according to claim 5, characterized in that: In step S3, the heat treatment temperature is 120°C and the heat treatment time is 10 hours.

7. The method for preparing a zeolite molecular sieve for adsorption and separation of carbon dioxide according to claim 6, characterized in that: In step S3, the washing times are 4 times, and the amount of carbon tetrachloride solvent used in each washing is 150 mL.

8. A zeolite molecular sieve for adsorption and separation of carbon dioxide, characterized in that: The method is prepared according to any one of claims 1 to 7.

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