High-hydrophobicity molecular sieve with super-strong VOC (volatile organic compound) adsorption capacity and preparation method of high-hydrophobicity molecular sieve
By optimizing the silicon-aluminum ratio and pore structure of the molecular sieve through dealumination treatment and gradient silanization modification, a dense hydrophobic layer is formed, which solves the contradiction between the hydrophobicity and adsorption capacity of traditional molecular sieves and achieves efficient VOCs adsorption and stability.
Patent Information
- Application Number
- CN202511089843.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-08-05
- Publication Date
- 2025-10-10
AI Technical Summary
Traditional Y-type molecular sieves are prone to damage to the pore structure and decrease in adsorption capacity when increasing their hydrophobicity. Silanization modification is prone to clogging the pores, making it difficult to achieve efficient VOCs adsorption under complex working conditions.
The silicon-aluminum ratio is optimized through dealumination treatment, a dense hydrophobic layer is formed by gradient silanization modification, and the mesoporous structure is optimized by combining tetrapropylammonium hydroxide to form a hydrophobic gradient from the inside to the outside. Post-treatment controls the integrity of the modification process.
The integrity and high hydrophobicity of the molecular sieve structure are achieved, ensuring the efficient diffusion and adsorption of VOCs molecules in a humid environment, and improving the adsorption capacity and stability.
Smart Images
Figure BDA0005533577280000081
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of adsorbents and preparation thereof, and in particular to a highly hydrophobic molecular sieve with super-strong VOC adsorption capacity and a preparation method thereof. Background Art
[0002] With the acceleration of industrialization and urbanization, the emission of volatile organic compounds (VOCs) has increased dramatically, posing a serious threat to the environment and human health. As a highly efficient adsorption material, molecular sieves have shown great potential in the field of VOCs treatment. However, traditional Y-type molecular sieves face two major technical bottlenecks in practical applications: one is the contradiction between hydrophobicity and adsorption capacity, that is, when hydrophobicity is improved by dealumination modification, it often leads to the destruction of the pore structure and a decrease in adsorption capacity; the other is that although silanization modification can enhance hydrophobicity, it is easy to clog the pores, further restricting the diffusion of VOCs molecules. In addition, the existing modification methods are mostly single technologies or simple combinations, lacking the coordinated regulation of the structure and performance of molecular sieves, and it is difficult to meet the demand for efficient adsorption under complex working conditions.
[0003] Therefore, the development of a new molecular sieve material with both super strong VOCs adsorption capacity and high hydrophobicity has become an urgent need in the current field of environmental governance. Summary of the Invention
[0004] The purpose of the present invention is to provide a highly hydrophobic molecular sieve with super VOC adsorption capacity and a preparation method thereof, to solve the above-mentioned problems, after the molecular sieve framework is subjected to dealumination treatment to obtain an appropriate silicon-aluminum ratio, the surface hydroxyl density is optimized, and suitable grafting sites are provided for subsequent silanization. During the gradient silanization process, the smaller molecule methyltrimethoxysilane preferentially forms a dense hydrophobic layer at the pore opening, and then the larger molecule trimethylchlorosilane constructs a secondary hydrophobic structure on the outer surface, forming a hydrophobic gradient from the inside to the outside. In the post-processing stage, the unreacted silanization agent is removed by precise temperature control, and the structural defects caused by the chemical treatment are repaired at the same time, and finally a molecular sieve with complete pores and hydrophobic surface is obtained, realizing the directional regulation and synergistic strengthening modification of the Y-type molecular sieve, and providing an effective way to develop molecular sieve materials with super VOC adsorption capacity and high hydrophobicity.
[0005] To achieve the above object, the present invention discloses a method for preparing a highly hydrophobic molecular sieve with super strong VOC adsorption capacity, comprising the following steps:
[0006] S1, dealumination pretreatment of NaY molecular sieve;
[0007] S2, performing gradient silanization modification on the NaY molecular sieve after dealuminization pretreatment;
[0008] S3. Post-processing.
[0009] Preferably, step S1 specifically comprises the following steps:
[0010] S1-1, calcining NaY molecular sieve in a muffle furnace at 500℃ for 2 hours to remove water adsorbed in the pores of the molecular sieve;
[0011] S1-2, mixing the calcined NaY molecular sieve with an acid solution, stirring and refluxing at 80-85℃ for 4-6 hours, then filtering, washing to pH 6-8, and drying at 110℃ for 12 hours to obtain the dealuminated and pretreated NaY molecular sieve.
[0012] Preferably, the acid solution in step S1-2 is a mixed acid solution of citric acid solution and oxalic acid solution, and the concentration ratio of citric acid solution to oxalic acid solution in the mixed acid solution is 1:1 to 3:1, and the solid-liquid ratio of NaY molecular sieve to acid solution is 1g:(5-15)mL.
[0013] Preferably, in step S2, the dealuminated and pretreated NaY molecular sieve is preliminarily modified by methyltrimethoxysilane, and the preliminarily modified NaY molecular sieve is deeply modified by trimethylchlorosilane.
[0014] Preferably, specifically comprising the following steps:
[0015] S2-1, placing the dealuminated NaY molecular sieve in a tube furnace, introducing nitrogen containing 8-10vol% saturated vapor of methyltrimethoxysilane, keeping the temperature in the tube furnace at 80-100℃, and reacting for 1.5-2h, then stopping heating and introducing dry nitrogen until the temperature in the tube furnace reaches room temperature after forming a preliminary hydrophobic layer;
[0016] S2-2, heating the tube furnace to 200-250℃, introducing nitrogen containing 20-30vol% saturated vapor of trimethylchlorosilane, and reacting for 2-5h, then filtering, washing, and drying to obtain the surface-modified NaY molecular sieve;
[0017] S2-3, placing the surface-modified NaY molecular sieve in a tetrapropylammonium hydroxide solution, and crystallizing at 150-170℃.
[0018] Preferably, the mass ratio of methyltrimethoxysilane and trimethylchlorosilane deposited on the NaY molecular sieve to the mass of the NaY molecular sieve is (0.1-1):(0.01-0.1):1, and the mass ratio of tetrapropylammonium hydroxide in the tetrapropylammonium hydroxide solution to the mass of the surface-modified NaY molecular sieve is (0.1-0.5):1.
[0019] Preferably, the post-treatment after step S3 is specifically to raise the modified molecular sieve to 550 DEG C at a temperature rising rate of 5 DEG C / min in a muffle furnace, and to bake for 4 hours to remove residual modification reagents and impurities, and to naturally cool to room temperature after the baking is completed to obtain the final high hydrophobicity molecular sieve with super strong VOC adsorption capacity.
[0020] The application also provides a high hydrophobicity molecular sieve with super strong VOC adsorption capacity prepared by the preparation method, wherein the SiO2 / Al2O3 silicon aluminum ratio of the high hydrophobicity molecular sieve is 40-50, and the water absorption rate is <10%.
[0021] The dealumination pretreatment controls the concentration of citric acid and the reaction conditions to remove part of the aluminum elements while maintaining the stability of the molecular sieve framework, so that the silicon aluminum ratio is increased to the interval of 40-50, which not only reduces the hydrophilicity of aluminum hydroxyl, but also avoids the collapse of the pore caused by excessive dealumination. The gradient silanization modification uses short-chain methyltrimethoxysilane and long-chain trimethylchlorosilane in steps to form a preliminary hydrophobic layer on the surface of the molecular sieve, and then performs deep modification inside the pore, and optimizes the mesoporous distribution with tetrapropylammonium hydroxide to make the hydrophobic groups uniformly cover without blocking the pore. The hydrophobic layer formed on the surface of the molecular sieve is dense and continuous, which maintains a high specific surface area while controlling the water absorption rate below 10%, ensuring that VOC molecules can still diffuse and be adsorbed efficiently in a humid environment.
[0022] Therefore, the application has the following beneficial effects:
[0023] (1) The application avoids the collapse of the molecular sieve framework by mild dealumination and gradient silanization modification, and maintains the integrity of the molecular sieve structure. At the same time, the optimized pore structure and increased specific surface area make the molecular sieve have stronger VOC adsorption capacity for VOC molecules; the gradient silanization modification forms a uniform and dense hydrophobic layer on the surface of the molecular sieve, effectively preventing the adsorption of water molecules, so that the water absorption rate is <10%. The post-treatment step improves the thermal stability and hydrothermal stability of the molecular sieve, ensuring its long-term effectiveness in practical applications.
[0024] (2) The present application cooperates with the silicon aluminum ratio through gradient modification to maintain the connectivity of the pore while improving the hydrophobicity, overcoming the interference of water competition adsorption on the VOC adsorption efficiency. In addition, the structure directing agent in the prior art is only used in the synthesis stage of the molecular sieve, while the present application introduces tetrapropylammonium hydroxide to optimize the mesoporous structure in the modification stage, further enhancing the adsorption stability of the molecular sieve in a high humidity environment.
[0025] (2) The present application ensures that the performance of the molecular sieve in the modification process is not affected by residual acid by supplementing the mass control point of the washing pH value, improves the stability and reliability of the product, and the modification is reliable and the process is simple.
[0026] The technical solution of the present invention is further described in detail below through examples. DETAILED DESCRIPTION
[0027] The technical solution of the present invention is further illustrated by the following examples.
[0028] Unless otherwise defined, technical or scientific terms used in the present invention shall have the same meaning as commonly understood by one of ordinary skill in the art to which the present invention belongs.
[0029] Furthermore, it should be understood that although this specification describes the embodiments, not every embodiment includes only one independent technical solution. This description is for clarity only. Those skilled in the art should consider the specification as a whole. The technical solutions in the various embodiments may also be appropriately combined to form other embodiments that are understandable to those skilled in the art. These other embodiments are also encompassed within the scope of protection of the present invention.
[0030] Example 1
[0031] This embodiment provides a highly hydrophobic molecular sieve with super strong VOC adsorption capacity, the preparation of which includes the following steps:
[0032] (1) Place 60 g of NaY molecular sieve in a muffle furnace, heat to 550°C at 5°C / min, and calcine for 2 hours. Mix the calcined molecular sieve with 0.5 L of a mixed acid solution of 0.2 mol / L citric acid and 0.2 mol / L oxalic acid, stir and reflux at 85°C for 6 hours. Filter the resulting product, wash with deionized water until the filtrate has a pH of 7, and dry at 110°C for 12 hours.
[0033] (2) 50 g of the dealumination-treated NaY molecular sieve was placed in a tube furnace, and nitrogen containing 10 vol% saturated vapor of methyltrimethoxysilane was introduced. The temperature in the tube furnace was maintained at 80° C. and the reaction was carried out for 1.5 h. After a preliminary hydrophobic layer was formed, heating was stopped and dry nitrogen was introduced until the temperature in the tube furnace reached room temperature. The temperature in the tube furnace was raised to 200° C. again, and nitrogen containing 20 vol% saturated vapor of trimethylchlorosilane was introduced. The reaction was carried out for 3 h. After filtration, washing, and drying, the surface-modified NaY molecular sieve was obtained. The surface-modified NaY molecular sieve was placed in 10 ml of a 0.3 g / ml tetrapropylammonium hydroxide solution at a crystallization temperature of 170° C.
[0034] (3) The modified molecular sieve was placed in a muffle furnace, heated to 550°C at a rate of 5°C / min, calcined for 4 hours, and naturally cooled to room temperature.
[0035] Example 2
[0036] This embodiment provides a highly hydrophobic molecular sieve with super strong VOC adsorption capacity, the preparation of which includes the following steps:
[0037] (1) Place 250 g of NaY molecular sieve in a muffle furnace, heat to 550°C at 5°C / min, and calcine for 2 hours. Mix the calcined molecular sieve with 2.5 L of a mixed solution of 0.2 mol / L citric acid and 0.1 mol / L oxalic acid, stir and reflux at 85°C for 4 hours. Filter the resulting product, wash with deionized water until the filtrate has a pH of 7, and dry at 110°C for 12 hours.
[0038] (2) 200 g of the dealumination-treated NaY molecular sieve was placed in a tube furnace, and nitrogen containing 10 vol% saturated vapor of methyltrimethoxysilane was introduced. The temperature in the tube furnace was maintained at 80° C. and the reaction was carried out for 1.5 h. After a preliminary hydrophobic layer was formed, heating was stopped and dry nitrogen was introduced until the temperature in the tube furnace reached room temperature. The temperature in the tube furnace was raised to 200° C. again, and nitrogen containing 25 vol% saturated vapor of trimethylchlorosilane was introduced. The reaction was carried out for 4 h. After filtration, washing, and drying, a surface-modified NaY molecular sieve was obtained. The surface-modified NaY molecular sieve was placed in 40 ml of a 0.5 g / mL tetrapropylammonium hydroxide solution at a crystallization temperature of 170° C.
[0039] (3) The modified molecular sieve was placed in a muffle furnace, heated to 550°C at a rate of 5°C / min, calcined for 4 hours, and naturally cooled to room temperature.
[0040] Example 3
[0041] This embodiment provides a highly hydrophobic molecular sieve with super strong VOC adsorption capacity, the preparation of which includes the following steps:
[0042] (1) Place 110 g of NaY molecular sieve in a muffle furnace, heat to 550°C at 5°C / min, and calcine for 2 hours. Mix the calcined molecular sieve with 1.5 L of 0.3 mol / L citric acid + 0.1 mol / L oxalic acid solution, and stir and reflux at 83°C for 5 hours. Filter the resulting product, wash with deionized water until the filtrate has a pH of 7, and dry at 110°C for 12 hours.
[0043] (2) 100 g of the dealumination-treated NaY molecular sieve was placed in a tube furnace, and nitrogen containing 10 vol% saturated vapor of methyltrimethoxysilane was introduced. The temperature in the tube furnace was maintained at 80° C. and the reaction was carried out for 1.5 h. After a preliminary hydrophobic layer was formed, heating was stopped and dry nitrogen was introduced until the temperature in the tube furnace reached room temperature. The temperature in the tube furnace was raised to 200° C. again, and nitrogen containing 25 vol% saturated vapor of trimethylchlorosilane was introduced. The reaction was carried out for 4 h. After filtration, washing, and drying, the surface-modified NaY molecular sieve was obtained. The surface-modified NaY molecular sieve was placed in 20 ml of a 0.5 g / mL tetrapropylammonium hydroxide solution at a crystallization temperature of 170° C.
[0044] (3) The modified molecular sieve was placed in a muffle furnace, heated to 500 °C at 5 °C / min, calcined for 3 h, and naturally cooled to room temperature.
[0045] Example 4
[0046] (1) Place 160 g of NaY molecular sieve in a muffle furnace, heat to 550°C at 5°C / min, and calcine at this temperature for 2 hours. Mix the calcined molecular sieve with 1.6 L of a mixed solution of 0.25 mol / L citric acid and 0.05 mol / L oxalic acid, and reflux at 75°C with stirring for 4.5 hours. The resulting product is filtered, washed with deionized water until the filtrate has a pH of 6, and dried at 110°C for 12 hours.
[0047] (2) 150 g of the dealumination-treated NaY molecular sieve was placed in a tube furnace, and nitrogen containing 10 vol% saturated vapor of methyltrimethoxysilane was introduced. The temperature in the tube furnace was maintained at 80° C. and the reaction was carried out for 2 h. After a preliminary hydrophobic layer was formed, heating was stopped and dry nitrogen was introduced until the temperature in the tube furnace reached room temperature. The temperature in the tube furnace was raised to 220° C. again, and nitrogen containing 28 vol% saturated vapor of trimethylchlorosilane was introduced. The reaction was carried out for 3.5 h. After filtration, washing, and drying, a surface-modified NaY molecular sieve was obtained. The surface-modified NaY molecular sieve was placed in 30 ml of a 0.6 g / mL tetrapropylammonium hydroxide solution at a crystallization temperature of 170° C.
[0048] (3) The modified molecular sieve was placed in a muffle furnace, heated to 550°C at a rate of 5°C / min, calcined for 4 hours, and naturally cooled to room temperature.
[0049] Comparative Example 1
[0050] This comparative example provides a highly hydrophobic molecular sieve, the preparation steps of which are the same as those of Example 1, except that in step (1), the calcined molecular sieve is mixed with the acid solution and stirred at 70° C. and refluxed for 5 hours.
[0051] Comparative Example 2
[0052] The comparative example provides a high hydrophobic molecular sieve, the preparation steps of which are the same as those of Example 1, except that in step (1), the stirring temperature of the mixture of the calcined molecular sieve and the acid solution is 90°C, and the stirring is refluxed for 5 hours.
[0053] Comparative Example 3
[0054] The comparative example provides a high hydrophobic molecular sieve, the preparation steps of which are the same as those of Example 2, except that in step (2), only methyltrimethoxysilane is used to form a preliminary hydrophobic layer.
[0055] Comparative Example 4
[0056] The comparative example provides a high hydrophobic molecular sieve, the preparation steps of which are the same as those of Example 2, except that in step (2), tetrapropylammonium hydroxide is not used.
[0057] The silicon-aluminum ratio, specific surface area, hydrophobicity (contact angle), and VOC adsorption capacity of the molecular sieves prepared in Examples 1-4 and Comparative Examples 1-4 were detected, and the results are shown in Table 1:
[0058] Table 1: Molecular sieve performance table
[0059]
[0060] According to the comparative analysis of the silicon-aluminum ratio and specific surface area retention rate of the molecular sieves of Example 1 and Comparative Examples 1-2, it is found that 80-85°C is the best temperature range for the synergistic effect of oxalic acid and citric acid: below 80°C, the oxalic acid does not dissociate sufficiently, and the dealumination rate decreases; above 85°C, the decomposition of citric acid may be accelerated, resulting in a decrease in complexing ability. The total reaction time is recommended to be set to 4-6 hours, of which the first 1-2 hours are dominated by oxalic acid for rapid dealumination, and the last 3-4 hours introduce citric acid for deep modification. Under this process, the specific surface area retention rate of the molecular sieve can reach more than 90%, the silicon-aluminum ratio is uniformly distributed, and there is no local aluminum enrichment or overdealuminization phenomenon, thereby ensuring the stability of the structure while achieving the synergistic improvement of hydrophobicity and adsorption capacity.
[0061] According to the water adsorption capacity and contact angle results of the molecular sieves prepared in Examples 1-4, it is found that the molecular sieves prepared by the present preparation method all have high or super-high hydrophobicity. Through comparison, the surface hydrophobicity of Example 1 is reduced due to insufficient amount of structure-directing agent, and the residual reagent in Example 3 hinders the formation of the hydrophobic layer due to the low calcination temperature. Examples 2 and 4 show that the synergistic effect of mixed acid dealumination + gradient silanization and the structure-directing agent promoting the generation of ordered mesopores reduces the surface free energy of the molecular sieve.
[0062] Comparing the water adsorption and contact angle results of the molecular sieves of Example 2 and Comparative Examples 3-4 shows that long-chain silane (TMCS) enhances hydrophobicity through steric hindrance, but requires TPAOH to optimize the pore structure to avoid clogging. TPAOH improves performance through the following mechanisms:
[0063] Pore regulation: Induce the formation of open mesoporous structure and reduce the blockage of pores caused by silanization.
[0064] Grafting promotion: Forming hydrogen bonds with silane molecules to increase the chemical grafting rate (from 30% of physical adsorption to more than 80% of chemical bonding).
[0065] Surface energy regulation: Reduce the surface silanol density to reduce the surface free energy.
[0066] Therefore, there is no complete hydrophobic layer in Comparative Example 3, and the short-chain silane has little pore blocking effect. In Comparative Example 4, the long-chain silane requires TPAOH to balance the pore structure.
[0067] According to the results of the adsorption amount of VOCs in Examples 1-4 and Comparative Examples 1-4, it is shown that the molecular sieve prepared by the preparation method provided by the present invention has a super strong adsorption capacity for VOCs. At the same time, due to the too low or too high acidification treatment temperature in Comparative Examples 1 and 2, its adsorption capacity is volatile. The acidification temperature is too low, resulting in insufficient dealumination, resulting in more residual aluminum in the skeleton. The adsorption amount of acetone (polar) decreases less than that of toluene (non-polar) due to the hydrogen bonding effect of the surface hydroxyl groups, resulting in an increase in the acetone / toluene adsorption ratio. Excessively high acidification temperature leads to accelerated decomposition of citric acid, resulting in local pH fluctuations, and triggering desiliconization (Si-O-Si breakage) of the molecular sieve skeleton. The residual aluminum in the skeleton and the exposure of the surface hydroxyl groups work together to cause a sharp drop in hydrophobicity (contact angle <120°), making it difficult for VOCs molecules to enter the pores.
[0068] Due to the difference in the setting of the hydrophobic layer in Comparative Examples 3 and 4, their adsorption capacity is also affected accordingly. In Comparative Example 3, the hydrophobic layer is incomplete. MTMS is a short-chain silane that can only form a single layer of coverage on the surface of the molecular sieve and cannot penetrate deep into the micropores to build a dense hydrophobic layer. In addition, the pore blockage is limited. The short-chain silane has a weak physical blocking effect on the pores, but the chemical grafting rate is low (about 60%), resulting in residual polar hydroxyl groups on the surface, thereby affecting the adsorption selectivity. The adsorption of toluene (non-polar) decreases more significantly due to insufficient hydrophobicity, while acetone (polar) is less affected by hydrogen bonding and has a smaller decrease in adsorption.
[0069] The lack of TPAOH in Comparative Example 4 reduced the chemical grafting rate of the TMCS long-chain silane, leaving some silane physically adsorbed and easily detached after high-temperature calcination. Furthermore, without the structural guidance of TPAOH, the pores contracted unevenly during silanization, resulting in localized pore collapse and reduced effective adsorption surface area. This increased surface silanol density weakened hydrophobicity, particularly affecting the adsorption of polar acetone.
[0070] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.
Claims
1. A method for preparing a highly hydrophobic molecular sieve with super strong VOC adsorption capacity, characterized in that: The following steps are involved: S1, dealumination pretreatment of NaY molecular sieve; S2, performing gradient silanization modification on the NaY molecular sieve after dealuminization pretreatment; S3. Post-processing.
2. The method for preparing a highly hydrophobic molecular sieve with super VOC adsorption capacity according to claim 1, characterized in that: Step S1 specifically includes the following steps: S1-1, calcining the NaY molecular sieve at 500°C in a muffle furnace for 2 hours to remove the water adsorbed in the pores of the molecular sieve; S1-2. The calcined NaY molecular sieve is mixed with an acid solution, stirred and refluxed at 80-85° C. for 4-6 hours, filtered, washed until the pH value is 6-8, and then dried at 110° C. for 12 hours to obtain a NaY molecular sieve after dealuminized pretreatment.
3. The method for preparing a highly hydrophobic molecular sieve with super VOC adsorption capacity according to claim 2, characterized in that: The acid solution in step S1-2 is a mixed acid solution of citric acid solution and oxalic acid solution, the concentration ratio of citric acid solution to oxalic acid solution in the mixed acid solution is 1:1 to 3:1, and the solid-liquid ratio of NaY molecular sieve to acid solution is 1g:(5-15)mL.
4. The method for preparing a highly hydrophobic molecular sieve with super VOC adsorption capacity according to claim 1, characterized in that: In step S2, the NaY molecular sieve after dealuminization pretreatment is preliminarily modified by methyltrimethoxysilane, and the preliminarily modified NaY molecular sieve is deeply modified by trimethylchlorosilane.
5. The method for preparing a highly hydrophobic molecular sieve with super VOC adsorption capacity according to claim 4, characterized in that: The specific steps include: S2-1. Place the dealuminated NaY molecular sieve in a tube furnace and introduce nitrogen containing 8-10 vol% saturated vapor of methyltrimethoxysilane. Maintain the temperature in the tube furnace at 80-100° C. for 1.5-2 hours. After a preliminary hydrophobic layer is formed, stop heating and introduce dry nitrogen until the temperature in the tube furnace reaches room temperature. S2-2, raising the temperature in a tube furnace to 200-250° C., introducing nitrogen gas containing 20-30 vol% saturated vapor of trimethylchlorosilane, reacting for 2-5 hours, filtering, washing, and drying to obtain a surface-modified NaY molecular sieve; S2-3. Place the surface-modified NaY molecular sieve in a tetrapropylammonium hydroxide solution at a crystallization temperature of 150-170°C.
6. The method for preparing a highly hydrophobic molecular sieve with super VOC adsorption capacity according to claim 5, characterized in that: The mass ratio of methyltrimethoxysilane and trimethylchlorosilane deposited on the NaY molecular sieve to the mass ratio of the NaY molecular sieve is (0.1-1): (0.01-0.1): 1, and the mass ratio of the tetrapropylammonium hydroxide in the tetrapropylammonium hydroxide solution to the surface-modified NaY molecular sieve is (0.1-0.5):
1.
7. The method for preparing a highly hydrophobic molecular sieve with super VOC adsorption capacity according to claim 5, characterized in that: The post-treatment in step S3 is specifically to heat the modified molecular sieve to 550°C in a muffle furnace at a heating rate of 5°C / min and calcine for 4 hours to remove residual modification reagents and impurities. After calcination, it is naturally cooled to room temperature to obtain the final highly hydrophobic molecular sieve with super VOC adsorption capacity.
8. A highly hydrophobic molecular sieve with super strong VOC adsorption capacity, characterized in that: The highly hydrophobic molecular sieve is prepared by the preparation method according to any one of claims 1 to 7, has a SiO2 / Al2O3 silicon-aluminum ratio of 40-50, and a water absorption rate of less than 10%.