Method for preparing hydrophobic 13X zeolite molecular sieve
By pre-calcining, organic solution cleaning, ion exchange and bissilane modification, a dense hydrophobic layer is formed, which solves the problems of insufficient hydrophobicity, adsorption capacity and cycle stability of 13X zeolite molecular sieve in humid conditions, and realizes its stable application in high humidity environment.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-30
- Publication Date
- 2026-03-10
AI Technical Summary
Existing technologies cannot simultaneously improve the hydrophobicity, adsorption capacity, and cycle stability of 13X zeolite molecular sieves, thus limiting their application in humid conditions.
A dense hydrophobic layer is formed through pre-calcination, organic solution cleaning, ion exchange, and bissilane modification, while retaining the pore structure and adsorption sites, thereby enhancing hydrophobicity and cycling stability.
Simultaneous improvement of the hydrophobicity, adsorption capacity and cycle stability of 13X zeolite molecular sieve under high humidity conditions was achieved, enhancing its application capability in humid environments.
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Figure CN121627013A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of molecular sieve preparation technology, and in particular to a method for preparing hydrophobic 13X zeolite molecular sieves. Background Technology
[0002] 13X zeolite molecular sieve, as a typical representative of octahedral zeolite (FAU type) molecular sieves, has a large pore size (approximately 0.74 nm) and a high specific surface area (700 m²). 2 / g to 900m 2 13X zeolite molecular sieves possess advantages such as high adsorption capacity and large adsorption capacity. Therefore, they are widely used in gas separation and purification. However, in the original structure of 13X zeolite molecular sieves, there are a large number of exchangeable sodium ions outside the framework, and the surface is rich in hydroxyl groups. This results in extremely high hydrophilicity of 13X zeolite molecular sieves. In environments with relative humidity > 40%, water molecules easily compete with target impurities (such as VOCs, methane, etc.) for adsorption sites on the 13X zeolite molecular sieve, causing a significant decrease in the adsorption capacity of the 13X zeolite molecular sieve for the target impurities, severely limiting its application in humid conditions.
[0003] Currently, the main processes for improving the hydrophobicity of 13X zeolite molecular sieves are: (1) ion exchange modification, which replaces sodium ions with cations such as potassium and calcium ions that have low hydration energy, thereby weakening the binding ability of water molecules with 13X zeolite molecular sieves; (2) silanization modification, which grafts hydrophobic groups (such as methyl and phenyl) onto the surface of 13X zeolite molecular sieves using silane modifiers, thereby reducing the hydrophobicity of 13X zeolite molecular sieves to below 8%; and (3) high-temperature calcination modification, which removes the surface hydroxyl groups of 13X zeolite molecular sieves through high-temperature calcination, thereby reducing the hydrophilic sites of 13X zeolite molecular sieves. These processes for improving the hydrophobicity of 13X zeolite molecular sieves generally cannot simultaneously achieve the synergistic optimization of the hydrophobicity, adsorption capacity, and cycle stability of 13X zeolite molecular sieves. Summary of the Invention
[0004] This application provides a method for preparing hydrophobic 13X zeolite molecular sieves to solve the following technical problem: how to simultaneously improve the hydrophobicity, adsorption capacity and cycle stability of 13X zeolite molecular sieves.
[0005] In a first aspect, embodiments of this application provide a method for preparing hydrophobic 13X zeolite molecular sieves, the method comprising: 13X zeolite molecular sieve was pre-calcined to obtain calcined molecular sieve; The calcined molecular sieve was cleaned using an organic solvent to obtain a cleaned molecular sieve. The cleaned molecular sieve is ion-exchanged using an ion-exchange solution to obtain a purified molecular sieve. The impurity-removing molecular sieve is modified using a silane mixture solution to obtain a modified molecular sieve; wherein the silane mixture solution contains at least two silane modifiers; The modified molecular sieve was sequentially filtered, washed, dried, and calcined to obtain a hydrophobic 13X zeolite molecular sieve.
[0006] Optionally, the mass m1 of the silane mixed solution and the mass m2 of the impurity-removing molecular sieve satisfy: m1:m2 = (1 to 50):1.
[0007] Optionally, the silane mixed solution includes a first silane modifier and a second silane modifier, wherein the amount of the first silane modifier n1 and the amount of the second silane modifier n2 satisfy: n1:n2=1:(1 to 10).
[0008] Optionally, the first silane modifier and the second silane modifier are at least one of methyltriethoxysilane, vinyltriethoxysilane, methyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, phenyltriethoxysilane, and diphenyldimethoxysilane.
[0009] Optionally, the molar concentration of silane molecules in the silane mixture is from 0.1 mol / L to 5 mol / L; and / or The mass of organic molecules in the organic solution is 30% to 100% of the mass of the organic solution.
[0010] Optionally, the mass m3 of the ion exchange liquid and the mass m4 of the cleaning molecular sieve satisfy the following: m3:m4 = (20 to 50):1.
[0011] Optionally, the molar concentration of the exchangeable ions in the ion exchange solution is from 0.1 mol / L to 1 mol / L; and / or The ion exchange solution contains at least one of potassium ions, ammonium ions, calcium ions, or aluminum ions.
[0012] Optionally, the modification temperature is 40°C to 150°C, and the modification time is 2 hours to 20 hours.
[0013] Optionally, the pre-calcination temperature is 200°C to 500°C, and the pre-calcination time is 2 hours to 4 hours; and / or The roasting temperature is 150°C to 300°C, and the roasting time is 2 hours to 5 hours.
[0014] Optionally, the washing temperature is 50°C to 80°C; and / or The drying temperature is 80°C to 120°C, and the drying time is 4 hours to 10 hours.
[0015] The technical solutions provided in this application have the following advantages compared with the prior art: This application provides a method for preparing hydrophobic 13X zeolite molecular sieves. The method first removes impurities clogging the pores of the 13X zeolite molecular sieve through pre-calcination and cleaning with an organic solution, resulting in a clean molecular sieve. Subsequently, ion exchange is performed on the sieve using an ion exchange solution to remove extra-framework impurities, forming clean and high-density active sites on the sieve surface. Next, a mixed solution containing at least two silane modifiers is used for modification: one type of silane modifier provides hydrophobic groups to enhance hydrophobicity, while the other type of silane modifier undergoes a cross-linking reaction with the first type, forming a stable hydrophobic layer. This hydrophobic layer not only fixes the hydrophobic groups and retains adsorption sites within the pores of the 13X zeolite molecular sieve, but also allows for fine-tuning of the surface pore size distribution and enhances the adsorption selectivity of the 13X zeolite molecular sieve for target impurities through size sieving effects. Simultaneously, the hydrophobic layer can withstand stress caused by airflow impact and temperature changes during multiple cycles, effectively improving the cycling stability of the molecular sieve. Attached Figure Description
[0016] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.
[0017] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0018] Figure 1 This is a schematic flowchart of a method for preparing hydrophobic 13X zeolite molecular sieves provided in an embodiment of this application. Detailed Implementation
[0019] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.
[0020] The range descriptions used in this application, such as numerical ranges and proportional ranges, include all possible sub-ranges and single numerical values within that range. For example, the range descriptions of "1 to 6" or "1~6" cover all sub-ranges (such as 1 to 3, 2 to 5, etc.) and single numbers (such as 1, 2, 3, 4, 5, 6) between 1 and 6. Unless otherwise specified, the terms "comprising" and others used herein mean "including but not limited to"; relational terms such as "first" and "second" are used only to distinguish different entities or operations and do not imply an actual order or relationship; "and / or" indicates that multiple situations can exist individually or simultaneously; expressions such as "at least one," "multiple," and "at least one" refer to any combination of the corresponding objects, including combinations of single or multiple objects. The proportional relationships involved in this document, such as mass ratios and molar ratios, should be understood as the correspondence between the first and second terms of a proportional formula, according to the order of description. The raw materials, reagents, instruments, and equipment used herein can all be obtained by purchasing from the market or by existing methods.
[0021] It should be noted that in the current process of improving the hydrophobicity of 13X zeolite molecular sieve, regarding the prior art (1) mentioned in the background art, the inventors found that the hydrophobicity of 13X zeolite molecular sieve improved by ion exchange modification is limited, and the water absorption rate of 13X zeolite molecular sieve can usually only be reduced to 12% to 15%. Regarding the prior art (2) mentioned in the background art, the inventors found that the silane modification method generally uses a single silane modifier, and a single silane modifier is prone to causing pore blockage of 13X zeolite molecular sieve, resulting in the 13X zeolite molecular sieve retaining less than 80% of the adsorption capacity for the target adsorbed impurities. Furthermore, the hydrophobic groups imparted by a single silane modifier have poor stability, and after multiple adsorption + regeneration cycles of 13X zeolite molecular sieve, these hydrophobic groups are easily detached. Regarding the prior art (3) mentioned in the background art, the inventors found that the hydrophobicity of the 13X zeolite molecular sieve obtained by the high temperature calcination modification method is reversible. In particular, the 13X zeolite molecular sieve is easy to recover its hydrophilicity after being exposed to a high humidity environment. Moreover, the high temperature calcination conditions may cause the skeleton of the 13X zeolite molecular sieve to collapse locally, which reduces the specific surface area of the 13X zeolite molecular sieve.
[0022] In view of the above-mentioned deficiencies of the prior art, this application provides the following technical solution: Figure 1 An exemplary schematic diagram of a method for preparing hydrophobic 13X zeolite molecular sieves provided in an embodiment of this application is shown. like Figure 1 As shown in the embodiments of this application, a method for preparing hydrophobic 13X zeolite molecular sieves is provided, the method comprising: S1. Pre-calcining 13X zeolite molecular sieve to obtain calcined molecular sieve; S2. The calcined molecular sieve is cleaned with an organic solution to obtain a cleaned molecular sieve; S3. The cleaned molecular sieve is ion-exchanged using an ion exchange solution to obtain a purified molecular sieve; S4. The impurity-removing molecular sieve is modified using a silane mixed solution to obtain a modified molecular sieve; wherein the silane mixed solution contains at least two silane modifiers; S5. The modified molecular sieve is sequentially filtered, washed, dried and calcined to obtain hydrophobic 13X zeolite molecular sieve.
[0023] It should be noted that after the ion exchange, the residual ion exchange solution in the molecular sieve can be separated and purified by filtration, washing and drying.
[0024] It should be noted that this modification can be carried out under conditions of heating and stirring.
[0025] It should be noted that the 13X zeolite molecular sieve can be a commercial molecular sieve, and the silica-to-alumina ratio of the 13X zeolite molecular sieve can be 1.1 to 1.5. Furthermore, the silica-to-alumina ratio of the 13X zeolite molecular sieve can be 1.1 to 1.3.
[0026] It should be noted that the calcination can be carried out under inert gas (such as nitrogen) conditions.
[0027] It should be noted that the method for preparing hydrophobic 13X zeolite molecular sieves provided in this application uses a core chain of pretreatment to optimize the substrate, synergistic modification with bissilanes, and post-treatment to solidify performance. Through precise matching of structure, performance, and mechanism of action, this method resolves the contradiction between improved hydrophobicity and decreased adsorption capacity and insufficient cycling stability in traditional modifications, achieving simultaneous optimization of the hydrophobicity, adsorption capacity, and cycling stability of 13X zeolite molecular sieves. The specific mechanism is as follows: I. Enhanced hydrophobicity: Dense cross-linked hydrophobic layers create a water molecule barrier.
[0028] The core of the hydrophobicity of 13X zeolite molecular sieve lies in reducing the interaction between the 13X zeolite molecular sieve surface and water molecules, which relies heavily on the dual guarantee of pretreatment activation sites and synergistic film formation by dual silanes. 1. Pretreatment lays the foundation for the surface: Pre-calcination can remove water, hydroxyl impurities, and template agent residues adsorbed on the surface of 13X zeolite molecular sieves, exposing more active silanol groups; at the same time, organic solvent cleaning can further remove oil-soluble impurities from the 13X zeolite molecular sieve, while ion exchange removes impurities (such as Ca) outside the 13X zeolite molecular sieve framework. 2+ Mg 2+This avoids impurities occupying the hydroxyl active sites of the 13X zeolite molecular sieve, ultimately resulting in a clean and high-density active site on the surface of the 13X zeolite molecular sieve, providing sufficient anchoring points for the covalent bonding of the silane mixed solution.
[0029] 2. Dual silanes synergistically form a dense hydrophobic layer: (1) The first silane modifier (containing strong hydrophobic groups, such as long-chain alkyl and trifluoropropyl) provides the core hydrophobic unit: the hydrophobic group of the first silane modifier repels the water molecules of 13X zeolite molecular sieve through steric hindrance effect, reducing the contact probability between the water molecules of 13X zeolite molecular sieve and the surface of 13X zeolite molecular sieve, which is the core of hydrophobicity. (2) The second silane modifier (containing crosslinking groups, such as amino and epoxy groups) plays a "bridging role": on the one hand, the second silane modifier and the active groups of the first silane modifier will undergo crosslinking reaction (such as the ring-opening reaction of amino and epoxy groups), on the other hand, the second silane modifier and the first silane modifier can form Si-O-Si covalent bonds with -Si-OH on the surface of 13X zeolite molecular sieve, and construct a double crosslinking network of silane + molecular sieve and silane + silane; (3) Multiple covalent bonds enable the hydrophobic layer to form a dense structure without pores, avoiding the defects (such as pinholes and cracks) in the hydrophobic layer caused by monolayer adsorption when modified with single silane. This prevents water molecules from penetrating to the surface of the 13X zeolite molecular sieve, ultimately achieving a water contact angle of ≥110° for the 13X zeolite molecular sieve (5° to 10° higher than that of the 13X zeolite molecular sieve modified with single silane). The static water adsorption capacity of the 13X zeolite molecular sieve is ≤0.06 g / g (far lower than that of the traditional 13X zeolite molecular sieve and the 13X zeolite molecular sieve modified with single silane).
[0030] II. Improved adsorption capacity: Preservation of pore structure + optimization of adsorption selectivity.
[0031] The core of the adsorption capacity of 13X zeolite molecular sieve lies in retaining effective adsorption sites and matching the molecular size of the target component. This is achieved through pretreatment to open up the pores and directional modification with bissilanes. 1. Pretreatment ensures unobstructed pores: Pre-calcination and cleaning with organic solutions can remove impurities (such as salts and organic matter remaining in the preparation process) that clog the pores of 13X zeolite molecular sieves. Ion exchange optimizes the framework charge distribution of 13X zeolite molecular sieves, avoiding the loss of adsorption sites caused by pore blockage and providing smooth diffusion channels for target adsorption impurities (such as CO2 and VOCs).
[0032] 2. Dual-silane modification avoids pore blockage: Traditional single-silane modifiers are prone to disordered aggregation of silane molecules, leading to pore blockage of the 13X zeolite molecular sieve and thus reducing the specific surface area of the 13X zeolite molecular sieve (reducing adsorption sites); however, the method provided in this application can constrain the distribution of the first silane through the cross-linking effect of the first and second silane modifiers. (1) The silane mixed solution forms an ultrathin cross-linked layer on the surface of the 13X zeolite molecular sieve through the cross-linking reaction of the first silane modifier and the second silane modifier, rather than entering the pores of the 13X zeolite molecular sieve, so that the specific surface area retention rate of the 13X zeolite molecular sieve is ≥92%, and the adsorption sites (such as framework cation sites and micropore adsorption sites) in the pores of the 13X zeolite molecular sieve are well preserved. (2) The surface pore size distribution of 13X zeolite molecular sieve can be finely adjusted in the cross-linking reaction of the first silane modifier and the second silane modifier through the silane mixed solution, so that the pores of 13X zeolite molecular sieve are concentrated in 0.95nm to 1.1nm (highly matched with the dynamic diameter of CO2 molecules of 0.33nm and the diameter of toluene molecules of 0.58nm). The adsorption selectivity of the target adsorbed impurities is improved through the size sieving effect, and the influence of competitive adsorption of water molecules is reduced.
[0033] 3. Synergistic effect enhances adsorption capacity: The hydrophobic layer only blocks water molecules and does not affect the interaction between the target adsorbed impurities and the adsorption sites within the pores of the 13X zeolite molecular sieve. Under high humidity conditions, water molecules are repelled by the hydrophobic layer on the surface of the 13X zeolite molecular sieve, while target adsorbed impurities such as CO2 and toluene can rapidly diffuse into the pores of the 13X zeolite molecular sieve and bind to the adsorption sites (CO2 adsorption capacity ≥1.9 mmol / g at 25℃ and RH 75%; toluene adsorption capacity ≥0.16 g / g at 40℃ and RH 75%). After ion exchange, the 13X zeolite molecular sieve framework has a more uniform charge distribution, which enhances the electrostatic adsorption of polar target impurities (such as CO2), further improving the adsorption capacity of the 13X zeolite molecular sieve (5.6% higher than that of single silane modification).
[0034] III. Improved Cyclic Stability: The cross-linked structure enhances the adhesion of the hydrophobic layer and the stability of the skeleton.
[0035] The core of the cyclic stability of 13X zeolite molecular sieve lies in the hydrophobic layer's resistance to shedding and the molecular sieve structure's resistance to cycling, relying on cross-linking reinforcement and full-process structural protection. 1. The cross-linked structure of bissilanes in silane mixed solutions is resistant to desorption: The bissilanes in silane mixed solutions can form a three-dimensional network composed of Si-O-Si covalent bonds and inter-silane cross-linking bonds, rather than single-point adsorption formed by single silane modification. This three-dimensional network has higher mechanical strength and can resist the stress caused by airflow impact and temperature changes during the adsorption and desorption cycle of 13X zeolite molecular sieve, thus preventing the hydrophobic layer of 13X zeolite molecular sieve from falling off. The hydrophobic layer is covalently bonded to the surface of the 13X zeolite molecular sieve (rather than physically adsorbed), which further reduces the risk of hydrophobic layer detachment. After multiple cycles, the water contact angle of the 13X zeolite molecular sieve is still ≥105°, and the change rate of water adsorption after multiple cycles is ≤3%.
[0036] 2. Ensuring the stability of the molecular sieve framework throughout the entire process: The ion exchange pretreatment removes impurity ions that can easily cause the framework of 13X zeolite molecular sieve to collapse, making the framework structure of 13X zeolite molecular sieve more stable and avoiding damage to the pore structure caused by the framework rupture of 13X zeolite molecular sieve during the circulation process. The post-treatment drying and calcination steps can solidify the covalent bonds between the two silane modifiers in the silane mixed solution and the surface of the 13X zeolite molecular sieve, further strengthening the bonding force between the hydrophobic layer and the 13X zeolite molecular sieve, while removing residual unreacted silane modifiers to prevent these residual silane modifiers from decomposing or falling off during the cycle and contaminating the pores.
[0037] 3. Enhanced adaptability to high temperature and high humidity conditions: The cross-linked hydrophobic layer has excellent chemical stability and will not hydrolyze or decompose under high temperature and high humidity conditions. The framework of 13X zeolite molecular sieve will not swell due to humidity changes. This ensures that the hydrophobicity, pore structure and adsorption sites of 13X zeolite molecular sieve remain stable during the circulation process, and the service life is significantly extended.
[0038] IV. The core contradiction-solving logic of simultaneous improvement of the three aspects.
[0039] The core contradiction in the modification of traditional 13X zeolite molecular sieves is that a thicker hydrophobic layer leads to pore blockage (resulting in a decrease in adsorption capacity), while a thinner hydrophobic layer results in poor resistance to shedding (insufficient cycle stability of 13X zeolite molecular sieves). The method provided in this application addresses this contradiction through the following design: 1. Dual silane synergy achieves hydrophobic layer densification and pore retention: The first silane modifier in the silane mixed solution provides hydrophobic function, while the second silane modifier achieves ultra-thin and dense film through cross-linking, achieving high hydrophobicity without thickening, while avoiding pore blockage of 13X zeolite molecular sieve. 2. Covalent bonding replaces physical adsorption: Multiple covalent bonds allow the hydrophobic layer to form an integrated structure with the 13X zeolite molecular sieve, which not only improves the durability of hydrophobicity (cycle stability) but also does not occupy adsorption sites in the pores (ensuring adsorption capacity). 3. Synergistic optimization of pretreatment and posttreatment: Pretreatment opens up the pores of 13X zeolite molecular sieve and activates the adsorption sites of 13X zeolite molecular sieve, while posttreatment solidifies the structure of 13X zeolite molecular sieve, providing a stable substrate and performance lock for the modification of silane mixed solution, ensuring that the effect of simultaneous improvement of the three is stably exerted in actual working conditions.
[0040] In summary, the present application provides a method for preparing hydrophobic 13X zeolite molecular sieves. This method achieves simultaneous improvement in the hydrophobicity, adsorption capacity, and cycle stability of 13X zeolite molecular sieves through a full-chain design of "structural optimization (pore retention + cross-linking membrane) + functional enhancement (hydrophobic groups + adsorption sites) + stability assurance (covalent bonding + framework protection)". It can be adapted to complex working conditions such as CO2 removal and VOCs adsorption under high humidity.
[0041] In some alternative embodiments, the mass m1 of the silane mixed solution and the mass m2 of the impurity-removing molecular sieve satisfy: m1:m2 = (1 to 50):1.
[0042] In these embodiments, a silane mixed solution with a mass-to-impurity molecular sieve mass ratio of (1 to 50):1 can form an ultrathin cross-linked layer on the surface of the 13X zeolite molecular sieve through the cross-linking reaction of the first and second silane modifiers in the silane mixed solution. This results in a specific surface area retention rate of ≥92% for the 13X zeolite molecular sieve, and the adsorption sites within the pores of the 13X zeolite molecular sieve are well preserved. At the same time, the cross-linking reaction of the first and second silane modifiers can also fine-tune the surface pore size distribution of the 13X zeolite molecular sieve and improve the adsorption selectivity for target adsorbed impurities through the size sieving effect, reducing the impact of competitive adsorption of water molecules.
[0043] The mass m1 of the silane mixture solution can be 1, 2, 3, 4, 5, 10, 15, 20, 25, 30, 35, 40, 45 or 50.
[0044] It should be noted that the mass m1 of the silane mixed solution and the mass m2 of the impurity-removing molecular sieve satisfy the following condition: m1:m2 = (10 to 30):1.
[0045] In some optional embodiments, the silane mixture includes a first silane modifier and a second silane modifier, wherein the amount of the first silane modifier n1 and the amount of the second silane modifier n2 satisfy: n1:n2=1:(1 to 10).
[0046] In these embodiments, a first silane modifier and a second silane modifier are used as a silane mixed solution, and the molar ratio of the first silane modifier and the second silane modifier is controlled to be 1:(1 to 10). An ultrathin cross-linked layer can be formed on the surface of the 13X zeolite molecular sieve through the cross-linking reaction of the first silane modifier and the second silane modifier, which effectively retains the adsorption sites in the pores of the 13X zeolite molecular sieve. At the same time, the cross-linking reaction of the first silane modifier and the second silane modifier can also fine-tune the surface pore size distribution of the 13X zeolite molecular sieve and improve the adsorption selectivity for target adsorbed impurities through the size sieving effect, reducing the influence of competitive adsorption of water molecules.
[0047] The amount of substance n2 of the second silane modifier can be 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10.
[0048] It should be noted that the amount of the first silane modifier n1 and the amount of the second silane modifier n2 satisfy the following: n1:n2=1:(3 to 7).
[0049] In some optional embodiments, the first silane modifier and the second silane modifier are at least one of methyltriethoxysilane, vinyltriethoxysilane, methyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, phenyltriethoxysilane, and diphenyldimethoxysilane.
[0050] In these embodiments, at least one of methyltriethoxysilane, vinyltriethoxysilane, methyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, phenyltriethoxysilane, and diphenyldimethoxysilane is used as the first silane modifier and the second silane modifier. An ultrathin cross-linked layer can be formed on the surface of the 13X zeolite molecular sieve through the cross-linking reaction of the first silane modifier and the second silane modifier. This effectively retains the adsorption sites within the pores of the 13X zeolite molecular sieve. At the same time, the cross-linking reaction of the first silane modifier and the second silane modifier can also fine-tune the surface pore size distribution of the 13X zeolite molecular sieve and improve the adsorption selectivity for target adsorbed impurities through the size sieving effect.
[0051] In some optional embodiments, the molar concentration of silane molecules in the silane mixture is from 0.1 mol / L to 5 mol / L; and / or The mass of organic molecules in the organic solution is 30% to 100% of the mass of the organic solution.
[0052] In these embodiments, the silane mixture, with a molar concentration of 0.1 mol / L to 5 mol / L, ensures sufficient first and second silane modifiers. The cross-linking reaction of the first and second silane modifiers forms an ultrathin cross-linked layer on the surface of the 13X zeolite molecular sieve, effectively preserving adsorption sites within the pores of the 13X zeolite molecular sieve. Simultaneously, the cross-linking reaction of the first and second silane modifiers can fine-tune the surface pore size distribution of the 13X zeolite molecular sieve and enhance adsorption selectivity for target impurities through a size sieving effect. Furthermore, in the organic solution, organic molecules comprising 30% to 100% of the organic solution's mass can effectively remove impurities clogging the pores of the 13X zeolite molecular sieve, facilitating the subsequent ion exchange process by optimizing the framework charge distribution of the 13X zeolite molecular sieve.
[0053] In a silane mixture, the molar concentration of the silane molecules can be 0.1 mol / L, 0.2 mol / L, 0.3 mol / L, 0.4 mol / L, 0.5 mol / L, 1.0 mol / L, 1.5 mol / L, 2.0 mol / L, 2.5 mol / L, 3.0 mol / L, 3.5 mol / L, 1.0 mol / L, 3.5 mol / L, 4.0 mol / L, 4.5 mol / L, or 5.0 mol / L.
[0054] The mass of organic molecules in the organic solution can be 30%, 40%, 50%, 60%, 70%, 80%, 90%, or 100% of the mass of the organic solution.
[0055] It should be noted that the molar concentration of silane molecules in the silane mixture can be from 0.2 mol / L to 3 mol / L.
[0056] It should be noted that the mass of organic molecules in this organic solution is 40% to 60% of the mass of the organic solution.
[0057] In some alternative embodiments, the mass m3 of the ion exchange liquid and the mass m4 of the cleaning molecular sieve satisfy: m3:m4 = (20 to 50):1.
[0058] In these embodiments, an ion exchange solution with a mass-to-mass ratio of (20 to 50):1 for the cleaning molecular sieve can remove impurity ions from the cleaning molecular sieve that could easily cause the framework of the 13X zeolite molecular sieve to collapse, thereby making the framework structure of the 13X zeolite molecular sieve more stable and avoiding damage to the pore structure caused by the rupture of the framework of the 13X zeolite molecular sieve during circulation.
[0059] The mass m3 of the ion exchange solution can be 20, 25, 30, 35, 40, 45 or 50.
[0060] The mass m3 of the ion exchange solution and the mass m4 of the molecular sieve being cleaned satisfy the following condition: m3:m4 = (30 to 40):1.
[0061] In some optional embodiments, the molar concentration of exchangeable ions in the ion exchange solution is from 0.1 mol / L to 1 mol / L; and / or The ion exchange solution contains at least one of potassium ions, ammonium ions, calcium ions, or aluminum ions.
[0062] In these embodiments, the ion exchange solution contains exchange ions with a molar concentration of 0.1 mol / L to 1 mol / L, and at least one of potassium ions, ammonium ions, calcium ions, or aluminum ions is used as the ion exchange solution. This allows for the removal of impurity ions from the molecular sieve that could easily cause the framework of the 13X zeolite molecular sieve to collapse, thereby making the framework structure of the 13X zeolite molecular sieve more stable.
[0063] The molar concentration of the exchange ions in the ion exchange solution can be 0.1 mol / L, 0.2 mol / L, 0.3 mol / L, 0.4 mol / L, 0.5 mol / L, 0.6 mol / L, 0.7 mol / L, 0.8 mol / L, 0.9 mol / L, or 1.0 mol / L.
[0064] It should be noted that the molar concentration of the exchange ions in the ion exchange solution can be from 0.3 mol / L to 0.6 mol / L.
[0065] In some alternative embodiments, the modification temperature is from 40°C to 150°C, and the modification time is from 2 hours to 20 hours.
[0066] In these embodiments, modification at temperatures of 40°C to 150°C and for times of 2h to 20h allows the first and second silane modifiers in the silane mixture to undergo a crosslinking reaction. This crosslinking reaction forms an ultrathin crosslinked layer on the surface of the 13X zeolite molecular sieve, effectively preserving the adsorption sites within the pores of the 13X zeolite molecular sieve. Simultaneously, the crosslinking reaction of the first and second silane modifiers can also fine-tune the surface pore size distribution of the 13X zeolite molecular sieve and enhance the adsorption selectivity for target impurities through the size sieving effect.
[0067] The modification temperature can be 40℃, 50℃, 60℃, 70℃, 80℃, 90℃, 100℃, 110℃, 120℃, 130℃, 140℃ or 150℃.
[0068] The modification time can be 2h, 3h, 4h, 5h, 10h, 15h or 20h.
[0069] It should be noted that the modification temperature can be between 50℃ and 100℃, and the modification time can be between 5 hours and 15 hours.
[0070] In some optional embodiments, the pre-calcination temperature is 200°C to 500°C, and the pre-calcination time is 2 hours to 4 hours; and / or The roasting temperature is 150°C to 300°C, and the roasting time is 2 hours to 5 hours.
[0071] In these embodiments, pre-calcination at 200°C to 500°C for 2 to 4 hours effectively removes adsorbed water, hydroxyl impurities, and template agent residues from the surface of the 13X zeolite molecular sieve, exposing more active silanol groups, which is beneficial for subsequent ion exchange and modification. Additionally, calcination at 150°C to 300°C for 2 to 5 hours, combined with drying, solidifies the covalent bonds between the two silane modifiers in the silane mixture and the surface of the 13X zeolite molecular sieve, further strengthening the bonding force between the hydrophobic layer and the 13X zeolite molecular sieve. Simultaneously, it removes residual unreacted silane modifiers, preventing these residual silane modifiers from decomposing or detaching during the circulation of the 13X zeolite molecular sieve and contaminating the pores.
[0072] The pre-baking temperature can be 200℃, 250℃, 300℃, 350℃, 400℃, 450℃ or 500℃.
[0073] The pre-calcination time can be 2h, 2.5h, 3.0h, 3.5h or 4.0h.
[0074] The roasting temperature can be 150℃, 160℃, 170℃, 180℃, 190℃, 200℃, 250℃ or 300℃.
[0075] The roasting time can be 2h, 2.5h, 3.0h, 3.5h, 4.0h, 4.5h or 5.0h.
[0076] It should be noted that the pre-baking temperature can be between 300℃ and 400℃.
[0077] It should be noted that the roasting temperature can be between 200℃ and 300℃. The roasting time can be between 3 hours and 4 hours.
[0078] In some alternative embodiments, the washing temperature is 50°C to 80°C; and / or The drying temperature is 80°C to 120°C, and the drying time is 4 hours to 10 hours.
[0079] In these embodiments, washing at a temperature of 50°C to 80°C can initially remove most of the silane mixture solution from the modified molecular sieve, preventing these residual silane modifiers from decomposing or detaching during the circulation of the 13X zeolite molecular sieve and contaminating the pores. Additionally, drying at a temperature of 80°C to 120°C for 4 to 10 hours can be combined with calcination to solidify the covalent bonds between the two silane modifiers in the silane mixture solution and the surface of the 13X zeolite molecular sieve, further strengthening the bonding force between the hydrophobic layer and the 13X zeolite molecular sieve, while simultaneously removing residual unreacted silane modifiers, preventing these residual silane modifiers from decomposing or detaching during the circulation of the 13X zeolite molecular sieve and contaminating the pores.
[0080] The washing temperature can be 50℃, 55℃, 60℃, 65℃, 70℃, 75℃ or 80℃.
[0081] The drying temperature can be 80℃, 85℃, 90℃, 95℃, 100℃, 105℃, 110℃, 115℃ or 120℃.
[0082] The drying time can be 4h, 5h, 6h, 7h, 8h, 9h or 10h.
[0083] It should be noted that the washing temperature can be between 60°C and 70°C.
[0084] It should be noted that the drying temperature can be between 90℃ and 110℃. The drying time can be between 6 hours and 8 hours.
[0085] The present application is further illustrated below with reference to specific embodiments. Experimental methods in the following embodiments that do not specify specific conditions are generally determined according to national / industry standards; if there is no corresponding national / industry standard, they are performed according to general international standards, conventional conditions, or conditions recommended by the manufacturer.
[0086] Example 1 like Figure 1 As shown, a method for preparing hydrophobic 13X zeolite molecular sieves includes: S1. Pre-calcining 13X zeolite molecular sieve to obtain calcined molecular sieve; S2. The calcined molecular sieve is cleaned with an organic solvent to obtain a cleaned molecular sieve; S3. Use an ion exchange solution to perform ion exchange on the cleaned molecular sieve, and then filter, wash and dry the ion-exchanged cleaned molecular sieve at 80°C to obtain a cleaned molecular sieve. S4. Modify the impurity-removing molecular sieve using a silane mixed solution to obtain a modified molecular sieve; wherein the silane mixed solution contains at least two silane modifiers; S5. The modified molecular sieve is sequentially filtered, washed, dried and calcined to obtain hydrophobic 13X zeolite molecular sieve.
[0087] The mass m1 of the silane mixed solution and the mass m2 of the impurity-removing molecular sieve satisfy the following ratio: m1:m2=10:1.
[0088] The silane mixed solution includes a first silane modifier and a second silane modifier, and the amount of the first silane modifier n1 and the amount of the second silane modifier n2 satisfy: n1:n2=1:3.
[0089] The first silane modifier is methyltriethoxysilane, and the second silane modifier is vinyltriethoxysilane.
[0090] The molar concentration of silane molecules in the silane mixture is 0.5 mol / L; The mass of organic molecules in an organic solution is 40% to 60% of the mass of the organic solution.
[0091] The mass m3 of the ion exchange solution and the mass m4 of the molecular sieve being washed satisfy the following ratio: m3:m4 = 20:1.
[0092] The molar concentration of exchangeable ions in the ion exchange solution is 1.0 mol / L; The ion exchange solution is potassium chloride.
[0093] The modification temperature was 60℃, and the modification time was 4 hours.
[0094] The pre-baking temperature is 300℃ and the pre-baking time is 3 hours; The roasting temperature was 300℃ and the roasting time was 4 hours.
[0095] The washing temperature is 70℃; The drying temperature (drying of the final product) is 90℃, and the drying time is 8 hours.
[0096] Example 2 Compared to Example 1, the differences in this example are as follows, while the rest are the same: The mass m1 of the silane mixed solution and the mass m2 of the impurity-removing molecular sieve satisfy the following ratio: m1:m2=10:1.
[0097] The silane mixed solution includes a first silane modifier and a second silane modifier, and the amount of the first silane modifier n1 and the amount of the second silane modifier n2 satisfy: n1:n2=1:3.
[0098] The first silane modifier is methyltriethoxysilane, and the second silane modifier is vinyltriethoxysilane.
[0099] The molar concentration of silane molecules in the silane mixture is 0.5 mol / L; The mass m3 of the ion exchange solution and the mass m4 of the molecular sieve being washed satisfy the following ratio: m3:m4 = 20:1.
[0100] The molar concentration of exchanged ions in the ion exchange solution is 1 mol / L; The ion exchange solution is calcium chloride.
[0101] The modification temperature was 60℃, and the modification time was 4 hours.
[0102] The pre-baking temperature was 220℃, and the pre-baking time was 2.5h; The roasting temperature was 250℃ and the roasting time was 3 hours.
[0103] The washing temperature is 55℃; The drying temperature is 80℃, and the drying time is 10 hours.
[0104] Example 3 Compared to Example 1, the differences in this example are as follows, while the rest are the same: The mass m1 of the silane mixed solution and the mass m2 of the impurity-removing molecular sieve satisfy the following ratio: m1:m2=25:1.
[0105] The silane mixed solution includes a first silane modifier and a second silane modifier, and the amount of the first silane modifier n1 and the amount of the second silane modifier n2 satisfy: n1:n2=1:3.
[0106] The first silane modifier is γ-aminopropyltriethoxysilane, and the second silane modifier is phenyltriethoxysilane.
[0107] The molar concentration of silane molecules in the silane mixture is 0.8 mol / L; The mass of organic molecules in an organic solution is 40% to 60% of the mass of the organic solution.
[0108] The mass m3 of the ion exchange solution and the mass m4 of the molecular sieve being washed satisfy the following ratio: m3:m4 = 15:1.
[0109] The molar concentration of exchangeable ions in the ion exchange solution is 0.8 mol / L; The ion exchange solution is aluminum chloride.
[0110] The modification temperature was 60℃, and the modification time was 4 hours.
[0111] The pre-baking temperature is 480℃, and the pre-baking time is 2 to 4 hours. The roasting temperature was 200℃ and the roasting time was 3 hours.
[0112] The washing temperature is 80℃; The drying temperature is 80℃ and the drying time is 6 hours.
[0113] Comparative Example 1 Compared to Example 1, the differences in this comparative example are as follows, while the rest are the same: Modification is not performed using silane mixtures.
[0114] The mass m3 of the ion exchange solution and the mass m4 of the molecular sieve being washed satisfy the following ratio: m3:m4=10:1.
[0115] The molar concentration of exchangeable ions in the ion exchange solution is 1.0 mol / L; The ion exchange solution is potassium chloride.
[0116] The roasting temperature was 300℃ and the roasting time was 4 hours.
[0117] Comparative Example 2 Compared to Example 1, the differences in this comparative example are as follows, while the rest are the same: A single silane modifier is used, specifically a methyltriethoxysilane solution with a molar concentration of 0.5 mol / L.
[0118] Comparative Example 3 Compared to Example 1, the differences in this comparative example are as follows, while the rest are the same: The amount of the first silane modifier n1 and the amount of the second silane modifier n2 satisfy the following: n1:n2=1:5.
[0119] Relevant experimental and effect data: Hydrophobic 13X zeolite molecular sieves obtained from each example and comparative example were collected and tested. The results are shown in Table 1. In Table 1, the test conditions for carbon dioxide adsorption were 25℃ and 75% relative humidity; the test conditions for toluene adsorption were 40℃ and 80% relative humidity. The test conditions for cycle stability were: nitrogen purging at 200℃ for 1 hour, followed by testing the water adsorption rate and the change in contact angle.
[0120] Table 1. Performance of hydrophobic 13X zeolite molecular sieves in various embodiments and comparative examples.
[0121] As shown in Table 1, the method for preparing hydrophobic 13X zeolite molecular sieve provided in this application achieves simultaneous improvement in the hydrophobicity, adsorption capacity, and cycle stability of 13X zeolite molecular sieve through a full-chain design of "structural optimization (pore retention + cross-linking membrane) + functional enhancement (hydrophobic groups + adsorption sites) + stability assurance (covalent bonding + framework protection)". It can maintain a high water absorption rate and contact angle even after multiple cycles.
[0122] Compared to Example 1, Comparative Example 1 did not use a silane mixed solution for modification, which resulted in poor hydrophobicity and adsorption capacity of the 13X zeolite molecular sieve obtained in Comparative Example 1. Furthermore, after multiple cycles of use, the water absorption rate and contact angle of the 13X zeolite molecular sieve changed significantly.
[0123] Compared to Example 1, Comparative Example 2 used a single silane modifier. Although the hydrophobicity and adsorption capacity of the 13X zeolite molecular sieve obtained in Comparative Example 2 were similar to those of the 13X zeolite molecular sieve obtained in this application, the water absorption rate and contact angle of the 13X zeolite molecular sieve in Comparative Example 2 changed to some extent after multiple cycles. This indicates that the cyclic stability of the 13X zeolite molecular sieve in Comparative Example 2 was poor.
[0124] Compared to Example 1, Comparative Example 3 used an excessive amount of the second silane modifier. The excessive amount of the second silane modifier would dilute the concentration and amount of the first silane modifier, affecting the hydrophobic modification of the 13X zeolite molecular sieve. At the same time, although the second silane modifier and the first silane modifier could still form a hydrophobic layer, the strength of the formed three-dimensional network structure was low. After multiple cycles, the hydrophobic groups were easy to fall off, affecting the stability of multiple cycles.
[0125] In summary, the present application provides a method for preparing hydrophobic 13X zeolite molecular sieves. This method takes pretreatment to optimize the substrate, synergistic modification with bissilane, and post-treatment to solidify the performance as the core link. Through precise matching of structure, performance, and mechanism of action, it solves the contradiction between improved hydrophobicity and decreased adsorption capacity and insufficient cycle stability in traditional modification, and achieves simultaneous optimization of hydrophobicity, adsorption capacity, and cycle stability of 13X zeolite molecular sieves.
[0126] In addition, the embodiments of this application provide a method for preparing hydrophobic 13X zeolite molecular sieves. This method is based on a synergistic process of "pretreatment to optimize the substrate + synergistic modification with bissilane + post-treatment to solidify the performance", which can significantly improve the hydrophobic properties of 13X zeolite molecular sieves as well as their adsorption performance of carbon dioxide and toluene under high humidity conditions.
[0127] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed in this application.
Claims
1. A process for preparing a hydrophobic 13X zeolite molecular sieve, characterized by, The method comprises: pre-calcining a 13X zeolite molecular sieve to obtain a calcined molecular sieve; cleaning the calcined molecular sieve using an organic solution to obtain a cleaned molecular sieve; ion exchanging the cleaned molecular sieve using an ion exchange solution to obtain a molecular sieve with impurities removed; modifying the molecular sieve with impurities removed using a silane mixed solution to obtain a modified molecular sieve; wherein the silane mixed solution comprises at least two silane modifiers; sequentially filtering, washing, drying and calcining the modified molecular sieve to obtain a hydrophobic 13X zeolite molecular sieve.
2. The method of claim 1, wherein, The mass m1 of the silane mixed solution and the mass m2 of the molecular sieve with impurities removed satisfy: m1:m2=(1-50):
1.
3. The method according to claim 1 or 2, characterized in that, The silane mixed solution comprises a first silane modifier and a second silane modifier, and the amount of substance n1 of the first silane modifier and the amount of substance n2 of the second silane modifier satisfy: n1:n2=1:(1-10).
4. The method of claim 3, wherein, The types of the first silane modifier and the second silane modifier are at least one of methyltriethoxysilane, vinyltriethoxysilane, methyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, phenyltriethoxysilane and diphenyldimethoxysilane.
5. The method according to claim 1 or 2, characterized in that, The molar concentration of silane molecules in the silane mixed solution is 0.1-5 mol / L; and / or The mass of organic molecules in the organic solution is 30%-100% of the mass of the organic solution.
6. The method of claim 1, wherein, The mass m3 of the ion exchange solution and the mass m4 of the cleaned molecular sieve satisfy: m3:m4=(20-50):
1.
7. The method of claim 1, wherein, The molar concentration of exchange ions in the ion exchange solution is 0.1-1 mol / L; and / or The types of exchange ions in the ion exchange solution are at least one of potassium ions, ammonium ions, calcium ions or aluminum ions.
8. The method of claim 1, wherein, The modification temperature is 40-150°C, and the modification time is 2-20 h.
9. The method of claim 1, wherein, The pre-calcination temperature is 200-500°C, and the pre-calcination time is 2-4 h; and / or The calcination temperature is 150-300°C, and the calcination time is 2-5 h.
10. The method of claim 1, wherein, The washing temperature is 50-80°C; and / or The drying temperature is 80-120°C, and the drying time is 4-10 h.