Hydrophobically modified zeolite, method of preparation and use thereof in co2 capture

Abstract

The application discloses a hydrophobic modified zeolite, a preparation method and application, and by means of in-situ structure regulation, a bifunctional modifier is introduced to change the surface energy of the zeolite pore and realize the remodeling of the zeolite structure, the zeolite grain size is reduced, the surface tension of the grain is increased, and the hydrophobic performance of the zeolite is greatly improved. The hydrophobic modification method breaks the barrier and difficulty that the existing modification method causes the adsorption performance of the modified zeolite to be reduced and the relationship between the hydrophobic and adsorption performances cannot be balanced, and realizes the technical advantage that the zeolite still maintains excellent CO2 adsorption capacity after being hydrophobically modified. The hydrophobic modified zeolite prepared by the application has the characteristics of high CO2 adsorption performance and strong hydrophobicity, and can save the flue gas drying and dehydration link in the actual operation of the zeolite, and save the process flow. The method has the characteristics of simple preparation mode, mild synthesis condition and no pollution, and has the potential for industrial production.

Description

Technical Field

[0001] This invention relates to the field of carbon dioxide capture, specifically to a hydrophobically modified zeolite, its preparation method, and its application in CO2 capture, particularly a method for modifying the internal pore structure of zeolite with a bifunctional modifier. Background Technology

[0002] In 2023, global energy-related CO2 emissions increased by 1.1%, rising by 410 million tons to a record high of 37.4 billion tons. Coal emissions accounted for over 65% of this increase. The Intergovernmental Panel on Climate Change (IPCC) has revised its estimates on the likelihood of exceeding 1.5°C of global warming in the coming decades, concluding that limiting warming to near 1.5°C or even 2°C is unattainable unless immediate, rapid, and large-scale reductions in greenhouse gas emissions are implemented. Given the impossibility of completely abandoning fossil fuels, carbon capture, utilization, and storage (CCUS) technology is considered a key technological means and a safety net for achieving temperature control targets. Amine solution absorption is considered the most mature post-combustion CO2 capture technology and is currently in the commercialization stage. Asia's largest carbon capture demonstration project for thermal power—the 500,000-ton-per-year carbon capture project at the Jiangsu Taizhou Power Plant of the State Energy Group—is already operational, and plans for a million-ton-per-year carbon capture capacity are underway. However, the technical drawbacks of the amine solution absorption method include high energy consumption, equipment corrosion, and secondary pollution caused by amine volatilization. Recent research on amine solutions focuses on reducing the water content in the solvent system or using low- or anhydrous phase change absorbents to reduce regeneration energy consumption and alleviate equipment corrosion. However, this leads to increased solution viscosity, resulting in increased energy consumption for liquid transport and pumping. Therefore, the overall energy consumption reduction is not significant, and there is limited room for further energy saving and consumption reduction. In contrast, solid adsorption technology does not involve additional energy consumption due to solvent evaporation, does not have equipment corrosion problems, does not produce volatile secondary pollution, and has a simple operating process, making it considered one of the carbon capture technologies with the greatest energy-saving potential.

[0003] In actual carbon capture processes, flue gas compositions are complex. Besides CO2, N2, and O2, it also contains impurities such as water vapor, making carbon capture challenging. As the core of solid adsorption technology, the adsorbent's CO2 adsorption performance and cycle stability directly determine the cost of carbon capture. To date, various solid adsorbents have been developed. Zeolite, an aluminosilicate with a unique ordered structure, is widely available, has low preparation costs, and possesses high porosity, high thermal stability, and chemical stability. In particular, its pore structure can be achieved through compositional variations, demonstrating great potential in CO2 capture. However, several issues remain to be addressed before its engineering application can be realized. Typically, flue gas contains a certain amount of moisture, and zeolite (especially low silica-to-alumina ratio zeolite) preferentially adsorbs water vapor due to its high hygroscopicity. On the one hand, water adsorbed on zeolite occupies adsorption active sites, reducing the zeolite's CO2 adsorption capacity. On the other hand, the hydroxyl groups generated by water cause the intermediate products formed after zeolite adsorbs CO2 to become stable bicarbonates, leading to an increase in the CO2 desorption temperature, even reaching 200°C, resulting in material deactivation. Therefore, solving the problem of zeolite adsorption of water vapor is of great significance for reducing CO2 capture costs. Currently reported commonly used hydrophobic modification methods mainly include the following:

[0004] Increasing the Si / Al ratio in the zeolite structure can reduce the water absorption rate of zeolite and even synthesize superhydrophobic zeolites. Hydrothermal generation and acid extraction, silicon tetrachloride method, ammonium hexafluorosilicate method, and chemical vapor deposition are common methods for eliminating polar ions in the zeolite framework and increasing the Si / Al ratio in the zeolite structure. The literature ACS Applied Materials & Interfaces, 2019, 11(4), 3946-3960 reported a method to increase the Si / Al ratio to 100 by adjusting the silicon content in CHA zeolite, achieving good CO2 molecular sieving ability in the presence of water vapor. The application document with publication number CN115818661A disclosed a method to increase the Si / Al ratio by high-temperature treatment of USY zeolite and removing aluminum ions in the framework using dilute acid solution. However, the above methods of increasing the Si / Al ratio of zeolite to improve hydrophobicity will lead to a decrease or even insufficiency of the zeolite's CO2 adsorption capacity, making it difficult to balance the relationship between adsorption capacity and hydrophobicity.

[0005] Surface hydrophobic coatings are another way to improve the hydrophobicity of zeolites. Application CN111302354A discloses a method of hydrophobic modification of zeolite molecular sieves using a toluene solution of chlorosilanes. The mixture is refluxed at 110–120°C, resulting in a water contact angle of 158–165 degrees for the modified zeolite, exhibiting hydrophobicity. Application CN116237011A discloses a modification method of impregnating zeolite with an acetone solution of an organic polymer containing fluorine functional groups. After drying and high-temperature carbonization (400–700°C), a hydrophobic coating is finally obtained on the zeolite surface. However, physical impregnation is difficult to control and can easily lead to uneven hydrophobic coatings on the zeolite surface. Furthermore, once the coating penetrates the material, it can easily clog pores, causing a decrease in CO2 adsorption capacity or slowed kinetics. Currently, zeolite hydrophobic modification methods often employ post-modification techniques, which have drawbacks such as complex processing, high pollution, and high control difficulty. Apart from the above, few inventions can maintain or improve the CO2 adsorption efficiency of zeolite after hydrophobic modification.

[0006] Therefore, given the reality that flue gas contains moisture, there is an urgent need to develop an efficient, simple, and rapid method for hydrophobic modification of zeolites, which can simultaneously maintain their high CO2 adsorption capacity and high selectivity, in order to realize their engineering applications. Summary of the Invention

[0007] The purpose of this invention is to address the problems of varying degrees of performance degradation caused by hydrophobic modification of zeolites and the high pollution and complexity of commonly used hydrophobic modification methods. This invention provides a modified zeolite, a method for preparing the modified zeolite, and its application in CO2 capture. This invention utilizes in-situ structural regulation, employing a bifunctional modifier during material preparation to adjust the surface characteristics and pore structure of the zeolite channels, achieving a synergistic improvement in hydrophobic modification and material adsorption performance. It offers advantages such as a simple method, no pollution, and controllable modification degree.

[0008] To achieve the above objectives, the present invention provides the following technical solution:

[0009] A method for preparing hydrophobically modified zeolite includes the following steps:

[0010] Silicon liquid is prepared by dissolving a silicon source in water;

[0011] Aluminum liquid is prepared by dissolving an aluminum source and a fluoride in water under an alkaline environment;

[0012] The molten silicon is added dropwise to the molten aluminum, and the mixture is thoroughly mixed after the addition is complete.

[0013] After the silicon source and aluminum source are mixed evenly, they are allowed to stand for 12-24 hours. After standing, they are heated and filtered to obtain a white solid.

[0014] The obtained white solid was washed until neutral and dried to obtain hydrophobically modified zeolite.

[0015] Furthermore, the silicon source includes: powdered sodium silicate with a modulus of 2.0 to 2.2, powdered sodium silicate with a modulus of 2.3 to 2.5, and powdered sodium silicate with a modulus of 2.8 to 3.0, and the solid-liquid ratio of the silicon source to water in the silicon liquid is 0.056 to 0.308 g / mL.

[0016] Furthermore, the silicon source is dissolved in water by ultrasonic dissolution to obtain molten silicon.

[0017] Furthermore, the aluminum liquid specifically refers to the solution of sodium aluminate, sodium hydroxide, and fluoride in water.

[0018] Furthermore, aluminum liquid is prepared by dissolving aluminum source, sodium hydroxide, and fluoride in water at a temperature of 50–90°C.

[0019] Furthermore, the fluoride includes one or more of sodium fluoride (NaF), sodium hydrogen fluoride (NaHF2), potassium fluoride (KF), potassium fluoride dihydrate (KF·2H2O), potassium fluorosilicate (K2SiF6), ammonium fluoride (NH4F), ammonium hydrogen fluoride (NH4HF2), silver fluoride (AgF), and lithium fluoride (LiF).

[0020] Furthermore, the molar ratio of aluminum in the aluminum source to hydroxide in the alkali to fluorine in the fluoride is 0.7–5.7:1.8–13:1, and the solid-liquid ratio of aluminum source to water is 0.017–0.121 g / mL.

[0021] Furthermore, under continuous stirring, the silicon liquid is added dropwise into the aluminum liquid, with a silicon source to aluminum source molar ratio of (0.78 to 5.02): 1, and then stirring is continued for 30 to 60 minutes to make the solution uniformly mixed.

[0022] Furthermore, after the silicon source and aluminum source are mixed evenly, they are allowed to stand for 12-24 hours, and then transferred to a 60-120℃ forced-air drying oven for 4-8 hours. After cooling to room temperature, the white solid product is centrifuged and filtered out.

[0023] Furthermore, the obtained white solid product is washed with a solvent until neutral. The solvent used for washing until neutral includes one or more of water, ethanol, methanol, ethyl acetate, dichloromethane, and toluene.

[0024] The core technical feature of this invention's hydrophobic modification method, which differs from existing methods, is that it utilizes the tunable structure of zeolite and employs an in-situ structural control strategy. A modifier is introduced during zeolite synthesis to participate in the crystallization process. The hydrophobic groups of the modifier are uniformly distributed on the pore surface, forming a uniform hydrophobic layer, significantly improving the hydrophobic effect of the zeolite. This avoids the problems of uneven hydrophobic layers and insignificant hydrophobic effects caused by existing methods such as physical impregnation or surface spraying. Furthermore, by adjusting the amount of modifier, the target product can be easily and quickly made to have different degrees of hydrophobic effect. The process is pollution-free and has potential for engineering applications.

[0025] The core technical feature that distinguishes this hydrophobically modified zeolite from existing modified zeolite materials is that, during the hydrophobic modification process, the modifier participates in the construction of the zeolite framework. This modifier increases the cation charge density within the zeolite framework, enhancing its interaction with CO2 molecules. Simultaneously, by controlling the structure to reduce the zeolite crystal size, abundant active adsorption sites are exposed, synergistically improving the CO2 adsorption capacity and efficiency of the hydrophobically modified zeolite. This results in an increase, rather than a decrease, in CO2 adsorption capacity after hydrophobic modification.

[0026] Beneficial effects

[0027] This invention discloses a method for hydrophobic modification of zeolite, which introduces a bifunctional modifier through in-situ structural regulation to change the surface energy of zeolite channels and reshape the zeolite structure, thereby reducing the zeolite grain size, increasing the surface tension of the grains, and significantly improving the hydrophobic properties of zeolite.

[0028] This invention discloses a method for hydrophobic modification of zeolite. The prepared hydrophobically modified zeolite exposes abundant active sites, and its pore size is reduced while its specific surface area is increased, enhancing its interaction force with CO2 molecules and significantly improving the CO2 adsorption performance and efficiency of the zeolite. The hydrophobic modification method proposed in this invention solves the problem that existing hydrophobic modification methods (such as increasing the silica-alumina ratio or surface hydrophobic coating) result in reduced CO2 adsorption capacity of the modified zeolite and an inability to balance the relationship between hydrophobic modification and CO2 adsorption performance. Specifically, the modified hydrophobic zeolite obtained by the method disclosed in this invention can significantly improve the hydrophobicity of zeolite while simultaneously greatly enhancing its CO2 adsorption performance and adsorption efficiency, achieving a synergistic effect.

[0029] The hydrophobic modification method proposed in this invention prepares modified hydrophobic zeolites, which possess both excellent CO2 adsorption performance and strong hydrophobicity. This method eliminates the need for flue gas drying and dehydration in actual zeolite production, thus simplifying the process. Furthermore, this method is characterized by its simple preparation method, mild synthesis conditions, and lack of pollution, making it a potential candidate for industrial production. Attached Figure Description

[0030] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0031] Figure 1 The following are scanning electron microscope (SEM) morphologies of the zeolite materials in specific embodiments. (a) SEM morphology of the original zeolite; (b) SEM morphology of the zeolite prepared in Example 1; (c) SEM morphology of the zeolite prepared in Example 2; (d) SEM morphology of the zeolite prepared in Example 3;

[0032] Figure 2 The XRD powder diffraction patterns of the original zeolite and the hydrophobically modified zeolite in the specific implementation embodiment are shown below.

[0033] Figure 3 The following are N2 adsorption isotherms and DFT model pore size distribution curves of zeolite materials at 77 K in specific embodiments: (a) original zeolite; (b) zeolite prepared in Example 1; (c) zeolite prepared in Example 2; (d) zeolite prepared in Example 3;

[0034] Figure 4 The following are CO2 adsorption isotherms of zeolite materials at 298 K in specific embodiments. (a) Original zeolite; (b) Zeolite prepared in Example 1; (c) Zeolite prepared in Example 2; (d) Zeolite prepared in Example 3;

[0035] Figure 5 The specific embodiment shows the water vapor adsorption isotherm of the zeolite material at 298K.

[0036] Figure 6 The N2 adsorption isotherms at 298 K are for the original zeolite in the specific implementation and the hydrophobically modified zeolite in Example 3. Detailed Implementation

[0037] To better understand the present invention, the present invention will be further described below with reference to the embodiments, but the content of the present invention is not limited to the following embodiments.

[0038] Example 1

[0039] The following explanation uses NaX zeolite as an example. To better illustrate the performance of hydrophobically modified zeolite, the original NaX (unmodified) is used as a comparison.

[0040] Accurately weigh 2.80 g of water glass and ultrasonically dissolve it in 10 mL of water to form a silicon solution; dissolve 2.67 g of sodium hydroxide, 2.42 g of sodium aluminate, and 0.30 g of potassium fluoride in 10 mL of water at 80 °C to form an aluminum solution. Add the silicon solution dropwise to the aluminum solution with continuous stirring, stirring for 30 min to ensure homogeneity. Let the mixture stand at room temperature for 12 h, then transfer it to an 80 °C forced-air drying oven and heat for 4 h. After cooling to room temperature, centrifuge and filter to obtain a white solid product. Wash the solid product with ethanol for 2 days, then with water for 2 days, changing the solution three times a day. Finally, dry the solid product in a vacuum drying oven at 130 °C to constant weight to obtain the modified zeolite.

[0041] The morphology of the hydrophobically modified zeolite prepared in this embodiment is shown in the figure. Figure 1 (b); with the original zeolite ( Figure 1 a) Compared to a) the modified zeolite, the particle size is significantly reduced, decreasing by a factor of 5. From Figure 2 As can be seen, the modified zeolite exhibits good crystallinity, and its characteristic peaks correspond one-to-one with those of the original NaX, proving that the crystal structure of the zeolite was not destroyed during the modification process. Figure 3 In the N2 adsorption isotherms at 77 K, both the original NaX and the modified zeolite prepared in this example exhibit typical Type I isotherms. The BET specific surface area of ​​the original NaX is 606.23 m². 2 / g, the BET specific surface area of ​​the modified zeolite is 684.46m². 2 / g, an increase of 12.90% compared to the original NaX. Figure 3 (a) and Figure 3 (b) shows the pore size distribution curves calculated using the DFT model, corresponding to the original NaX and the hydrophobically modified zeolite prepared in this embodiment, respectively. The comparison shows that the pore size of the original NaX is mainly concentrated at 1.57 nm, while the pore size of the hydrophobically modified zeolite prepared in this embodiment is mainly concentrated at 1.22 nm. The increase in specific surface area and the decrease in pore size confirm that the structure of the hydrophobically modified zeolite has changed. This change is beneficial for the material to adsorb CO2 molecules, improving its CO2 adsorption capacity. Figure 4 (a) and Figure 4 This conclusion is confirmed in (b). Through the synergistic effect of reduced pore size, increased specific surface area, and the resulting abundance of exposed active adsorption sites, the hydrophobically modified zeolite prepared in this example exhibits a CO2 adsorption capacity of 3.39 mmol / g at a partial pressure of 298 K and 10 kPa (10% CO2 content in coal-fired flue gas). This represents an 18.53% increase compared to the original zeolite NaX (2.86 mmol / g), or 1.18 times that of the original NaX. Figure 5The hydrophobic modification effect of the material was further demonstrated in the study. At 298 K and 20% RH, the water absorption of the original NaX was 317.07 cm³. 3 / g, the water absorption of the hydrophobically modified zeolite in this embodiment is 292.65cm³. 3 / g, a decrease of 7.70% compared to the previous value.

[0042] Example 2

[0043] The following explanation uses NaX zeolite as an example. To better illustrate the performance of hydrophobically modified zeolite, the original NaX (unmodified) is used as a comparison.

[0044] Accurately weigh 4.74 g of anhydrous sodium metasilicate and ultrasonically dissolve it in 10 mL of water to form a silicon solution; dissolve 0.78 g of sodium hydroxide, 1.38 g of sodium aluminate, and 0.40 g of ammonium fluoride in 10 mL of water at 80 °C to form an aluminum solution; add the silicon solution dropwise to the aluminum solution with continuous stirring for 30 min to ensure uniform mixing. Let the above mixture stand at room temperature for 18 h, then transfer it to a 90 °C forced-air drying oven and heat for 5 h. After cooling to room temperature, centrifuge and filter to obtain a white solid product. Wash the solid product with methanol for 2 days and with water for 2 days, changing the solution three times a day. Finally, dry the solid product in a vacuum drying oven at 130 °C to constant weight to obtain the modified zeolite.

[0045] The morphology of the hydrophobically modified zeolite prepared in this embodiment is shown in the figure. Figure 1 (c); with primitive zeolite ( Figure 1 a) Compared to a), the particle size of modified zeolite is significantly reduced, decreasing by a factor of 7. From Figure 2 It can be observed that the modified zeolite has good crystallinity, and its characteristic peaks correspond one-to-one with those of the original NaX, proving that the crystal structure of the zeolite was not destroyed during the modification process. Figure 3 In (c), the modified zeolite prepared in this embodiment exhibits a typical Type I isotherm in its N2 adsorption isotherm at 77 K, with a BET specific surface area of ​​725.04 m². 2 / g, an increase of 19.60% compared to the original NaX. Figure 3 (c) is the pore size distribution curve of the hydrophobically modified zeolite prepared in this embodiment, calculated by the DFT model. The pore size is further reduced compared to Example 1, with the main pore size distribution concentrated at 0.89 nm. Figure 4 In (c), the hydrophobically modified zeolite prepared in this embodiment exhibits a CO2 adsorption capacity of 3.76 mmol / g at a partial pressure of 298 K and 10 kPa (CO2 content in coal-fired flue gas is 10%). This represents a 31.47% increase in CO2 adsorption capacity compared to the original NaX, which is 1.31 times that of the original NaX. Figure 5As shown, the water absorption of the hydrophobically modified zeolite in this embodiment is 233.49 cm³. 3 / g, a decrease of 26.36% compared to the previous value.

[0046] Example 3

[0047] The following explanation uses NaX zeolite as an example. To better illustrate the performance of hydrophobically modified zeolite, the original NaX (unmodified) is used as a comparison.

[0048] Accurately weigh 6.16g of sodium silicate (modulus 2.0–2.2) and ultrasonically dissolve it in 10mL of water to form a silica liquid; dissolve 1.56g of sodium hydroxide, 0.83g of sodium aluminate, and 0.60g of sodium fluoride in 10mL of water at 80℃ to form an aluminum liquid; add the silica liquid dropwise to the aluminum liquid with continuous stirring for 30 minutes until they are thoroughly mixed. Let the above mixture stand at room temperature for 24 hours, then transfer it to a 100℃ forced-air drying oven and heat it for 6 hours. After cooling to room temperature, centrifuge and filter to obtain a white solid product. Wash the solid product with methanol for 2 days and with ethanol for 2 days, changing the solution three times a day. Finally, dry the solid product in a vacuum drying oven at 130℃ to constant weight to obtain the modified zeolite.

[0049] The morphology of the hydrophobically modified zeolite prepared in this embodiment is shown in the figure. Figure 1 (d). With the original zeolite ( Figure 1 a) Compared to a), the particle size of modified zeolite is significantly reduced, decreasing by a factor of 10. From Figure 2 It can be observed that the modified zeolite has good crystallinity, and its characteristic peaks correspond one-to-one with those of the original NaX, proving that the crystal structure of the zeolite was not destroyed during the modification process. Figure 3 In (d), the modified zeolite prepared in this embodiment exhibits a typical Type I isotherm in its N2 adsorption isotherm at 77 K, with a BET specific surface area of ​​1114.15 m². 2 / g, an increase of 83.78% compared to the original NaX. Figure 3 (d) is the pore size distribution curve of the hydrophobically modified zeolite prepared in this embodiment, calculated by the DFT model. The pore size is further reduced compared to Example 1, with the main pore size distribution concentrated at 0.78 nm. Figure 4 In (d), the hydrophobically modified zeolite prepared in this embodiment exhibits a CO2 adsorption capacity of 4.43 mmol / g at a partial pressure of 298 K and 10 kPa (CO2 content in coal-fired flue gas is 10%). This represents a 54.89% increase in CO2 adsorption capacity compared to the original NaX, which is 1.55 times that of the original NaX. Figure 5 As shown, the water absorption of the hydrophobically modified zeolite in this embodiment is 185.96 cm³. 3 / g, a decrease of 41.35% compared to the previous value. Figure 6Further testing was conducted on the nitrogen adsorption isotherms of the hydrophobically modified zeolite and the original NaX prepared in this embodiment. The nitrogen adsorption capacity of the material was defined as 70 kPa (70% nitrogen content in flue gas, pressure 100 kPa). Figure 6 As can be seen, the nitrogen adsorption capacities of the original NaX and the hydrophobically modified zeolite prepared in this example are 0.075 mmol / g and 0.050 mmol / g, respectively. Based on the Ideal Solution Adsorption Theory (IAST), the CO2 / N2 selectivity of the original NaX and the hydrophobically modified zeolite prepared in this example are calculated to be 266.9 and 620.2, respectively. Therefore, the CO2 / N2 selectivity of the hydrophobically modified zeolite prepared in this example is 1.34 times higher than that of the original zeolite.

[0050] Comparative Example 1

[0051] Using the hydrophobic modification method described in Example 1 of CN116237011A, raw NaX was impregnated in a mixed solution of polyvinylidene fluoride (PVDF) and acetone, followed by drying and calcination to obtain hydrophobically modified zeolite. Using the same testing method as in this patent, the results showed that the CO2 adsorption capacity of the obtained hydrophobically modified zeolite decreased by 20%. The experimental results verify that the CO2 adsorption capacity of the modified zeolite obtained using PVDF as a modifier decreases, while the present invention maintains excellent CO2 adsorption performance while performing hydrophobic modification.

[0052] The results above show that the modified hydrophobic zeolite prepared by the hydrophobic modification method proposed in this invention can significantly improve the hydrophobicity of the zeolite and at the same time greatly improve the CO2 adsorption performance of the zeolite, even exceeding the CO2 adsorption performance of the original zeolite, achieving a dual synergistic effect.

[0053] The embodiments of the present invention have been described in detail above, but the present invention is not limited to the described embodiments. For those skilled in the art, various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles of the present invention, and these variations still fall within the protection scope of the present invention.

[0054] Matters not covered in this invention are common knowledge.

Claims

1. A method for preparing hydrophobically modified zeolite, comprising the following steps: Silicon liquid is prepared by dissolving a silicon source in water; Aluminum liquid is prepared by dissolving an aluminum source and a fluoride in water under an alkaline environment; The molten silicon is added dropwise to the molten aluminum, and the mixture is thoroughly mixed after the addition is complete. After the silicon liquid and aluminum liquid are mixed evenly, they are allowed to stand. After standing, they are heated and filtered to obtain a white solid. The obtained white solid was washed until neutral and dried to obtain hydrophobically modified zeolite; The fluoride includes one or more of sodium fluoride, sodium hydrogen fluoride, potassium fluoride, potassium fluoride dihydrate, potassium fluorosilicate, ammonium fluoride, ammonium hydrogen fluoride, silver fluoride, and lithium fluoride.

2. The preparation method according to claim 1, characterized in that, The silicon source includes one or more of sodium silicate, sodium metasilicate anhydrous, sodium metasilicate pentahydrate, and sodium metasilicate nonahydrate.

3. The preparation method according to claim 2, characterized in that, The sodium silicate comprises: powdered sodium silicate with a modulus of 2.0 to 2.2, powdered sodium silicate with a modulus of 2.3 to 2.5, and powdered sodium silicate with a modulus of 2.8 to 3.0, wherein the solid-liquid ratio of silicon source to water in the silicon liquid is 0.056 to 0.308 g / mL.

4. The preparation method according to claim 1, characterized in that, The aluminum source is sodium aluminate.

5. The preparation method according to claim 1, characterized in that, The molar ratio of aluminum in the aluminum source: hydroxide ions in the alkali: fluorine in the fluoride is 0.7~5.7:1.8~13:

1.

6. The preparation method according to claim 1, characterized in that, The solid-liquid ratio of aluminum source to water is 0.017~0.121 g / mL.

7. The preparation method according to claim 1, characterized in that, The molar ratio of silicon to aluminum in the silicon and aluminum sources is (0.78~5.02):

1.

8. The preparation method according to claim 7, characterized in that, The obtained white solid product is washed with a solvent until neutral, said solvent including one or more of water, ethanol, methanol, ethyl acetate, dichloromethane, and toluene.

9. A hydrophobically modified zeolite obtained by the preparation method according to any one of claims 1-8.

10. The application of the hydrophobically modified zeolite according to claim 9 in CO2 capture.

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