Composite material for separating aluminum chloride catalyst from PAO and preparation method of composite material

Abstract

The invention relates to the technical field of materials, and provides a composite material for separating an aluminum chloride catalyst in PAO and a preparation method of the composite material. The preparation method of the composite material for separating the aluminum chloride catalyst in the PAO comprises the following steps: mixing an MOF material and an organic solvent to obtain a suspension, then adding a grafting reagent, carrying out heating reaction, carrying out solid-liquid separation, and drying to obtain an MOF material with the surface modified with the grafting reagent; and adding the MOF material with the surface modified with the grafting reagent into a solution containing a deep eutectic solvent, dipping, carrying out solid-liquid separation, and drying to obtain the composite material for separating the aluminum chloride catalyst from the PAO. The composite material provided by the invention realizes advantage complementation of MOF and DES, improves the adsorption performance and selectivity of aluminum chloride, reduces environmental pollution, provides a new way for aluminum chloride separation, and is of great significance to development of the coal-based PAO production industry.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of materials, and particularly relates to a composite material for separating an aluminum chloride catalyst in PAO and a preparation method thereof. BACKGROUND

[0002] Coal-based poly-alpha-olefin (PAO) as a high-performance synthetic lubricating oil base oil occupies an important position in modern industry. In the production process of coal-based PAO, the use of aluminum chloride catalyst is indispensable. However, the separation of the aluminum chloride catalyst has become a key problem restricting the improvement of production efficiency and product quality.

[0003] Traditional separation methods such as distillation and extraction are feasible to a certain extent, but have many drawbacks. The distillation process has high energy consumption, and is prone to decomposition or deterioration of high-boiling-point or heat-sensitive substances, thereby reducing product quality. The extraction method often needs a large amount of organic solvent, which not only has high cost, but also causes serious environmental pollution problems due to the volatilization and residue of the organic solvent, and does not conform to the development concept of green chemistry. SUMMARY

[0004] The purpose of the present application is to provide a composite material for separating an aluminum chloride catalyst in PAO and a preparation method thereof, and to solve the problems.

[0005] To achieve the above-mentioned application purposes, the technical solutions adopted by the present application are as follows: In a first aspect, the present application provides a preparation method of a composite material for separating an aluminum chloride catalyst in PAO, comprising: mixing a MOF material and an organic solvent to obtain a suspension, then adding a grafting reagent and heating to react, solid-liquid separation and drying to obtain a MOF material with a surface modified with a grafting reagent; adding the MOF material with the surface modified with the grafting reagent into a solution containing a deep eutectic solvent, impregnating, solid-liquid separation and drying to obtain a composite material for separating an aluminum chloride catalyst in PAO.

[0006] Preferably, the MOF material is selected from one or more of UiO-66, UiO-66, MIL-101 and ZIF-8.

[0007] UiO-66 is a metal-organic framework material composed of zirconium ions and terephthalic acid ligands. It possesses high thermal and chemical stability, and the strong chemical bonds between nodes and linkers in its structure allow the material to withstand harsh processing conditions. This stability provides a good foundation for immobilized DES (delta-melt solvent). Its pore structure can effectively accommodate DES, which can be fixed within its pores through physical adsorption or chemical bonding. MIL-101, formed by chromium ions and terephthalic acid ligands, has an extremely large specific surface area and pore volume. Its pore structure is rich, exhibiting two different sizes of cage structures, and it possesses good water stability. These large cages can accommodate a large amount of DES, which can be fixed within the pores through electrostatic interactions, hydrogen bonding, and other methods. Its excellent water stability allows for the stable immobilization of DES in applications involving aqueous systems or humid environments. ZIF-8 is formed by zinc ions and imidazole ligands, possessing a zeolite-like topology with good thermal and chemical stability, moderate pore size, permanent microporosity, and high specific surface area. Its microporous structure can physically confine DES, ensuring its uniform distribution within the pores. Simultaneously, the surface functional groups of ZIF-8 can interact with DES through hydrogen bonds or coordination bonds, thereby achieving effective DES immobilization.

[0008] Preferably, the organic solvent is selected from one or more of toluene, xylene, ethylbenzene, acetone, ethyl acetate, tetrahydrofuran, and dimethylformamide.

[0009] Preferably, the mass ratio of the organic solvent to the MOF material is 2-5:1.

[0010] Optionally, the mass ratio of the organic solvent to the MOF material can be any value between 2:1, 3:1, 4:1, 5:1, or 2-5:1.

[0011] Preferably, the grafting reagent comprises a silane coupling agent and an organic crosslinking agent. The silane coupling agent is selected from one or more of γ-aminopropyltriethoxysilane, epoxysilane, vinylsilane, methacryloxysilane, and γ-glycidoxypropyltrimethoxysilane. The organic crosslinking agent is selected from one or more of glutaraldehyde, hexamethylenediamine, bismaleimide, melamine-formaldehyde resin, epoxy resin, and dicumyl peroxide.

[0012] The silane coupling agent in the grafting reagent reacts with MOF as follows: Hydrolysis: Silane coupling agents typically contain hydrolyzable groups, such as methoxy (-OCH3) or ethoxy (-OC2H5). Under appropriate conditions, these groups undergo hydrolysis. For example, in γ-aminopropyltriethoxysilane (KH-550), the ethoxy group hydrolyzes to produce silanol (-Si(OH)3) and ethanol. Silanol is a highly reactive group that can condense with the hydroxyl groups (-OH) on the surface of MOF materials.

[0013] Condensation reaction: The surface of MOF materials is rich in hydroxyl groups, which may be generated due to the dissociation of coordinated water molecules on metal nodes or the hydrolysis of functional groups on organic ligands. Silanol groups can undergo condensation reactions with hydroxyl groups on the MOF surface to form Si-OM (M represents the metal atom in the MOF) or Si-OC (C represents the carbon atom in the organic ligand) bonds. For example, in the UiO-66 MOF material, the silanol after hydrolysis of the silane coupling agent can undergo condensation reactions with the zirconium-hydroxyl (Zr-OH) on the UiO-66 surface or the hydroxyl groups after hydrolysis of the carboxyl groups on the terephthalic acid ligand, thereby grafting the silane coupling agent onto the MOF surface.

[0014] Coordination with open metal sites: Some MOF materials contain open metal sites, and the amino groups (such as KH-550) or other functional groups with lone pairs of electrons in the silane coupling agent molecule can coordinate with these open metal sites. This coordination can further enhance the binding force between the silane coupling agent and the MOF, and can also change the local chemical environment of the MOF, which may affect the adsorption, catalytic and other properties of the MOF.

[0015] The organic cross-linking agent in the grafting reagent reacts with MOF as follows: Reactions based on functional groups: Organic crosslinking agents possess various reactive functional groups, such as the maleimide group in bismaleimide and the amino and hydroxymethyl groups in melamine-formaldehyde resin. These functional groups can react with functional groups on the surface of MOF materials. For example, when the surface of the MOF material contains amino groups (such as some amino-functionalized MOFs), the maleimide group can undergo a Michael addition reaction with the amino group. If the MOF surface has carboxyl groups, the hydroxymethyl groups in melamine-formaldehyde resin can undergo an esterification reaction with them.

[0016] Free radical initiation: Some organic crosslinking agents containing unsaturated bonds, such as peroxide crosslinking agents (diisopropylbenzene peroxide), generate free radicals under heating or in the presence of an initiator. These free radicals can initiate polymerization reactions of unsaturated bonds (if present) on the organic ligands on the MOF surface. For example, in MOF materials containing alkenyl functionalized organic ligands, the free radicals generated by the peroxide crosslinking agent can cause the alkenyl groups to undergo crosslinking polymerization, thereby grafting the organic crosslinking agent onto the MOF surface.

[0017] Preferably, the mass ratio of the silane coupling agent to the organic crosslinking agent is 1-3:1; And / or, The mass ratio of the grafting reagent to the MOF material is 0.2-1:1.

[0018] Optionally, the mass ratio of the silane coupling agent to the organic crosslinking agent can be any value between 1:1, 2:1, 3:1, or 1-3:1; the mass ratio of the grafting reagent to the MOF material can be any value between 0.2:1, 0.3:1, 0.4:1, 0.5:1, 0.6:1, 0.7:1, 0.8:1, 0.9:1, 1:1, or 0.2-1:1.

[0019] Preferably, the heating reaction is carried out at a temperature of 40-80°C for 2-48 hours.

[0020] Optionally, the temperature of the heating reaction can be any value between 40°C, 50°C, 60°C, 70°C, 80°C or 40-80°C, and the time can be any value between 2h, 6h, 12h, 24h, 36h, 48h or 2-48h.

[0021] Preferably, the eutectic solvent includes one or more of the following: choline chloride and ethylene glycol, urea and malonic acid, betaine and glycerol, choline chloride and glycerol, urea and malic acid, and betaine and xylitol.

[0022] To achieve efficient separation of aluminum chloride and PAO, it is necessary to conduct in-depth research and screening of suitable DES composition. Specifically, this can be approached from the following aspects: (1) Analysis of the interaction between DES and aluminum chloride: In-depth study of the interaction types between DES and aluminum chloride, such as hydrogen bonding, ion-dipole interaction, and complexation. By analyzing and determining the influence of factors such as DES composition, temperature, and concentration on the dissolution behavior of aluminum chloride, an accurate dissolution model can be constructed. Based on this model, it can be determined which DES composition is more conducive to the dissolution of aluminum chloride, providing a theoretical basis for screening.

[0023] (2) Investigate the compatibility between DES and PAO: The compatibility between DES and PAO under different conditions was determined by experiment, and a detailed phase diagram was drawn to visually present the law of change of compatibility between the two with different conditions. Based on the phase diagram, DES compositions with poor compatibility with PAO under different conditions were screened out, thus laying the foundation for achieving efficient phase separation.

[0024] (3) Study on interfacial properties and interaction forces: Using interfacial chemistry theory and molecular simulation methods, we will explore in depth the interfacial properties between DES and PAO, such as interfacial tension and interfacial energy, as well as interaction forces, such as van der Waals forces and electrostatic forces. At the same time, we will analyze the driving forces of phase separation, such as density difference and interfacial tension difference, as well as the phase separation mechanism, including spontaneous phase separation and induced phase separation. Through these studies, we will understand how different DES compositions affect interfacial properties and interaction forces, thereby screening out DES compositions that help improve phase separation performance.

[0025] (4) Adjusting the structure and properties of DES: Explore methods to reduce the compatibility of DES with PAO by adjusting its structure and properties, such as changing the types and ratios of hydrogen bond donors and acceptors. Study the effects of DES with different structures and properties on the compatibility with PAO, and screen out DES compositions that can significantly reduce the compatibility between the two to achieve efficient separation of aluminum chloride and PAO.

[0026] Preferably, the mass ratio of the deep eutectic solvent to the MOF material is 0.1-1:1; And / or, The immersion temperature is 30-70℃, and the time is 12-24h.

[0027] Optionally, the mass ratio of the deep eutectic solvent to the MOF material can be any value between 0.1:1, 0.2:1, 0.3:1, 0.4:1, 0.5:1, 0.6:1, 0.7:1, 0.8:1, 0.9:1, 1:1, or 0.1:1; the impregnation temperature can be any value between 30℃, 40℃, 50℃, 60℃, 70℃, or 30-70℃; and the time can be any value between 12h, 16h, 18h, 20h, 22h, 24h, or 12-24h.

[0028] Secondly, this application provides a composite material for separating aluminum chloride catalyst from PAO, which is prepared using the method described above.

[0029] Compared with the prior art, this application has the following beneficial effects: This application provides a composite material for separating aluminum chloride catalysts in PAO and a method for preparing the same. The innovative technology of immobilizing DES onto MOF materials achieves complementary advantages between MOF and DES, generating new synergistic effects. The pore structure of MOF provides an excellent carrier and confined environment for DES, preventing DES loss and improving its stability and utilization rate; the special properties of DES enhance the interaction between MOF and aluminum chloride, significantly improving the adsorption performance and selectivity of aluminum chloride.

[0030] Metal-organic frameworks (MOFs), as a novel class of porous materials, possess ultra-high specific surface area, tunable pore structure, and abundant surface functional groups, demonstrating great potential in gas adsorption, separation, and catalysis. Eutectic solvents (DES), composed of hydrogen bond acceptors (HBAs) and hydrogen bond donors (HBDs) in a stoichiometric ratio, are novel green solvents with advantages such as low volatility, good solubility, and designability, exhibiting unique performance in separation processes. This invention delves into the synergistic mechanism of MOFs and DES, developing an innovative and practical aluminum chloride separation technology, providing crucial support for the efficient and green development of coal-based PAO production.

[0031] This application elucidates the interaction mechanism between MOF-DES composite materials and aluminum chloride at the molecular level, the recognition and binding process of aluminum chloride, and the microscopic mechanism of mass transfer. It proposes the aforementioned composite material and its preparation method, laying a solid theoretical foundation for aluminum chloride separation technology. Compared with traditional separation methods, this technology avoids the use of large amounts of organic solvents and chemical reagents, reduces environmental pollution, and improves separation efficiency and product quality. It has significant innovative value and broad application prospects, and is expected to promote the technological upgrading and sustainable development of the coal-based PAO production industry. Attached Figure Description

[0032] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0033] Figure 1 This is a photograph of the MOF-DES composite material prepared in Example 1 of the present invention for separating aluminum chloride catalyst in PAO. Detailed Implementation

[0034] To make the technical problems, technical solutions, and beneficial effects of this application clearer, the following detailed description is provided in conjunction with embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0035] The following description is based on specific embodiments.

[0036] Example 1 This embodiment provides a composite material for separating aluminum chloride catalyst from PAO, and its preparation method is as follows: Material preparation MOF material: UiO-66 was selected as the MOF material. 10g of UiO-66 was weighed and placed in 40g of toluene. The mixture was ultrasonically dispersed in an ultrasonic cleaner for 45 minutes to ensure the formation of a uniform and stable suspension.

[0037] Grafting reagent: Prepare a grafting reagent containing 6 g of γ-aminopropyltriethoxysilane and 4 g of bismaleimide. Slowly add the grafting reagent dropwise to the above suspension, continuously stirring with a magnetic stirrer during the addition, and control the reaction temperature at 65°C using an oil bath. The reaction continues for 30 hours, during which the state of the reaction system is closely observed.

[0038] DES solution: To prepare the DES solution, choline chloride and ethylene glycol were mixed in a 1:3 molar ratio as the DES system, and the solution was prepared with a concentration of 0.4 g / mL.

[0039] MOF grafting and DES fixation process MOF grafting: After the reaction was complete, the reaction product was transferred to a centrifuge tube and centrifuged at 5500 r / min for 15 minutes to separate the solid product. The product was washed six times with 30 mL of toluene each time to thoroughly remove unreacted grafting reagent and impurities. The washed product was then placed in a vacuum drying oven and dried at 60 °C to constant weight to obtain UiO-66 material with the grafting reagent modified on its surface.

[0040] DES Immobilization: 5g of the surface-modified UiO-66 material was added to 5mL of DES solution, and the mixture was stirred and impregnated at 45℃ for 20h using a magnetic stirrer to ensure that DES was fully adsorbed onto the pores and surface of the UiO-66 material. The DES-immobilized UiO-66 material was then separated by centrifugation at 4500r / min for 20min and dried in a 50℃ drying oven for 5h to obtain the MOF-DES composite material.

[0041] Figure 1 This is a photograph of the MOF-DES composite material prepared in Example 1 for separating aluminum chloride catalyst in PAO. Figure 1 As shown, the original white powdery UiO-66 MOF material (left) transforms into a pale yellow to brownish-yellow powder (right) after grafting modification and deep eutectic solvent (DES) immobilization, indicating that DES has been successfully loaded into the pores and surface of the MOF material.

[0042] aluminum chloride removal test 100 mL of a simulated PAO solution containing 10 g / L aluminum chloride was prepared, and 2 g of the prepared MOF-DES composite material was added to this solution. The mixture was stirred and reacted at room temperature for 3 h. After the reaction was completed, the composite material was separated by filtration, and the concentration of aluminum chloride in the filtrate was determined by inductively coupled plasma atomic emission spectrometry (ICP-AES). The removal rate of aluminum chloride was calculated. The determination showed that the removal rate of aluminum chloride reached 93%.

[0043] Example 2 This embodiment provides a composite material for separating aluminum chloride catalyst from PAO, and its preparation method is as follows: Material preparation MOF material: Take 8g of MIL-101 and put it into 30g of xylene, and ultrasonically disperse it for 50 minutes to form a suspension.

[0044] Grafting reagents: Measure 4g of epoxysilane and 4g of hexamethylenediamine as grafting reagents, and slowly add them dropwise to the suspension. Control the reaction temperature at 55℃ using a heating mantle, and stir the reaction for 35 hours.

[0045] DES solution: DES is composed of urea and malonic acid in a molar ratio of 1:2.5, and is prepared into a solution with a concentration of 0.35 g / mL.

[0046] MOF grafting and DES fixation process MOF grafting: After the reaction was completed, the product was filtered and separated, washed 7 times with xylene (25 mL each time), and dried under vacuum at 58 °C to constant weight to obtain the modified MIL-101 material.

[0047] DES immobilization: 4g of modified MIL-101 material was added to 4.5mL of DES solution and impregnated at 42℃ for 22h with stirring. Then, it was centrifuged at 4200r / min for 18 minutes and dried at 48℃ for 6h to obtain MOF-DES composite material.

[0048] aluminum chloride removal test A simulated PAO solution containing 8 g / L aluminum chloride was prepared in 150 mL. 3 g of MOF-DES composite material was added, and the mixture was stirred at 35 °C for 4 h. After the reaction was complete, the solution was filtered, and the aluminum chloride concentration in the filtrate was determined by ICP-AES. The aluminum chloride removal rate was calculated to be 82%.

[0049] Example 3 This embodiment provides a composite material for separating aluminum chloride catalyst from PAO, and its preparation method is as follows: Material preparation MOF material: 6g ZIF-8 was placed in 20g tetrahydrofuran and ultrasonically dispersed for 35 minutes to obtain a suspension.

[0050] Grafting reagent: Weigh 4.5g of vinylsilane and 3.5g of melamine-formaldehyde resin as grafting reagents, add them slowly dropwise, and stir the reaction at 75℃ for 18h.

[0051] DES solution: Prepare a DES solution consisting of betaine and glycerol in a 1:2 molar ratio, with a concentration of 0.45 g / mL.

[0052] MOF grafting and DES fixation process MOF grafting: After reaction, centrifuge (5000 r / min, 10 min), wash 6 times with tetrahydrofuran, 20 mL each time, and vacuum dry at 68 °C to constant weight to obtain surface-modified ZIF-8 material.

[0053] DES immobilization: 3g of modified ZIF-8 material was added to 3.5mL of DES solution and stirred and impregnated at 58℃ for 16h. The mixture was then centrifuged (4300r / min, 15min) to separate the components and dried at 53℃ for 4h to obtain the MOF-DES composite material.

[0054] aluminum chloride removal test Prepare 120 mL of a simulated PAO solution containing 12 g / L aluminum chloride, add 2.5 g of MOF-DES composite material, and stir the reaction at room temperature for 3.5 h. After filtration, determine the aluminum chloride concentration in the filtrate using ICP-AES. The calculated aluminum chloride removal rate reached 92%.

[0055] Example 4 This embodiment provides a composite material for separating aluminum chloride catalyst from PAO, and its preparation method is as follows: Material preparation MOF material: UiO-66 was selected as MOF material. 12g of UiO-66 was weighed and placed in 50g of acetone, and ultrasonically dispersed for 60 minutes to form a uniform and stable suspension.

[0056] Grafting reagent: Prepare a grafting reagent containing 7g γ-glycidoxypropyltrimethoxysilane and 5g epoxy resin. Slowly add the grafting reagent dropwise to the above suspension, continuously stirring with a mechanical stirrer during the addition, and control the reaction temperature at 70℃ using a water bath. The reaction continues for 40 hours, during which the state of the reaction system is observed periodically.

[0057] DES solution: To prepare the DES solution, choline chloride and glycerol were mixed in a 1:4 molar ratio as the DES system, and the solution was prepared with a concentration of 0.3 g / mL.

[0058] MOF grafting and DES fixation process MOF grafting: After the reaction was complete, the reaction product was transferred to a centrifuge tube and centrifuged at 6000 r / min for 20 minutes to separate the solid product. The product was washed seven times with 35 mL of acetone each time to thoroughly remove unreacted grafting reagent and impurities. The washed product was then placed in a vacuum drying oven and dried at 65 °C to constant weight to obtain UiO-66 material with the grafting reagent modified on its surface.

[0059] DES Immobilization: 6g of the surface-modified UiO-66 material was added to 6mL of DES solution, and the mixture was stirred and impregnated at 50℃ for 24h using a mechanical stirrer to ensure that DES was fully adsorbed into the pores and surface of the UiO-66 material. The DES-immobilized UiO-66 material was then separated by centrifugation at 5000r / min for 25min and dried in a 55℃ drying oven for 6h to obtain the MOF-DES composite material.

[0060] aluminum chloride removal test 150 mL of a simulated PAO solution containing 12 g / L aluminum chloride was prepared, and 3 g of the prepared MOF-DES composite material was added to this solution. The mixture was stirred and reacted at 30 °C for 4 h. After the reaction, the composite material was separated by filtration, and the concentration of aluminum chloride in the filtrate was determined by inductively coupled plasma atomic emission spectrometry (ICP-AES). The removal rate of aluminum chloride was calculated. The determination showed that the removal rate of aluminum chloride reached 86%.

[0061] Example 5 This embodiment provides a composite material for separating aluminum chloride catalyst from PAO, and its preparation method is as follows: Material preparation MOF material: Take 10g of MIL-101 and put it into 40g of ethyl acetate, and ultrasonically disperse for 55 minutes to form a suspension.

[0062] Grafting reagents: Measure 6g of methacryloxysilane and 4g of glutaraldehyde as grafting reagents, and slowly add them dropwise to the suspension. Control the reaction temperature at 60℃ using a heating mantle, and stir the reaction for 45 hours.

[0063] DES solution: DES is composed of urea and malic acid in a molar ratio of 1:3.5, and is prepared into a solution with a concentration of 0.4 g / mL.

[0064] MOF grafting and DES fixation process MOF grafting: After the reaction was completed, the product was filtered and separated, washed 8 times with ethyl acetate (30 mL each time), and dried under vacuum at 60 °C to constant weight to obtain the modified MIL-101 material.

[0065] DES immobilization: 5g of modified MIL-101 material was added to 5.5mL of DES solution and impregnated at 45℃ for 26h with stirring. Then, it was centrifuged at 4500r / min for 20min and dried at 50℃ for 7h to obtain MOF-DES composite material.

[0066] aluminum chloride removal test A simulated PAO solution containing 10 g / L aluminum chloride was prepared in 200 mL. 4 g of MOF-DES composite material was added, and the mixture was stirred at 40 °C for 5 h. After the reaction was complete, the solution was filtered, and the aluminum chloride concentration in the filtrate was determined by ICP-AES. The aluminum chloride removal rate was calculated to be 83%.

[0067] Example 6 This embodiment provides a composite material for separating aluminum chloride catalyst from PAO, and its preparation method is as follows: Material preparation MOF material: 8g ZIF-8 was placed in 30g dimethylformamide and ultrasonically dispersed for 45 minutes to obtain a suspension.

[0068] Grafting reagent: Weigh 5g of epoxy silane and 3g of dicumyl peroxide as grafting reagents, add them slowly dropwise, and stir the reaction at 80℃ for 24h.

[0069] DES solution: Prepare a DES solution consisting of betaine and xylitol in a molar ratio of 1:2.5, with a concentration of 0.5 g / mL.

[0070] MOF grafting and DES fixation process MOF grafting: After reaction, centrifuge (5500 r / min, 12 min), wash 7 times with dimethylformamide, 25 mL each time, and vacuum dry at 70 °C to constant weight to obtain surface-modified ZIF-8 material.

[0071] DES immobilization: 4g of modified ZIF-8 material was added to 4mL of DES solution and stirred and impregnated at 60℃ for 18h. The mixture was then centrifuged (4800r / min, 18min) to separate the materials and dried at 55℃ for 5h to obtain the MOF-DES composite material.

[0072] aluminum chloride removal test Prepare 180 mL of a simulated PAO solution containing 15 g / L aluminum chloride, add 3.5 g of MOF-DES composite material, and stir the reaction at room temperature for 4 h. After filtration, the aluminum chloride concentration in the filtrate is determined by ICP-AES, and the aluminum chloride removal rate is calculated to be 95%.

[0073] Comparative Example 1 This comparative example provides a material that does not undergo grafting treatment, and its preparation method is as follows: 10g of UiO-66 was placed in 40g of toluene and ultrasonically dispersed for 45 minutes to form a suspension. A DES solution (concentration 0.4g / mL) composed of 5g of choline chloride and ethylene glycol in a 1:3 molar ratio was added to the suspension. The mixture was stirred and impregnated at 45℃ for 20h, centrifuged at 4500r / min for 20 minutes, and dried at 50℃ for 5h to obtain the MOF-DES composite material.

[0074] Aluminum chloride removal test: Prepare 100 mL of simulated PAO solution containing 10 g / L aluminum chloride, add 2 g of composite material, stir at room temperature for 3 h, and then determine the aluminum chloride concentration in the filtrate by ICP-AES. The removal rate was calculated to be 68%.

[0075] Comparative analysis: Compared with the 93% removal rate in Example 1, the removal rate of the composite material without grafting treatment was significantly reduced (68% vs 93%), proving that grafting treatment plays a key role in improving the performance of composite materials.

[0076] Comparative Example 2 This comparative example provides a composite material using only hydrogen bond donors, and its preparation method is as follows: 10g of UiO-66 was placed in 40g of toluene and ultrasonically dispersed for 45 minutes to form a suspension. Grafting reagent (6g of γ-aminopropyltriethoxysilane and 4g of bismaleimide) was added, and the mixture was reacted at 65℃ for 30h to obtain surface-modified UiO-66. 5g of the modified UiO-66 was added to a solution containing only hydrogen bond donors (ethylene glycol, concentration 0.4g / mL), impregnated at 45℃ for 20h, and dried at 50℃ for 5h to obtain the MOF-DES composite material.

[0077] Aluminum chloride removal test: Prepare 100 mL of simulated PAO solution containing 10 g / L aluminum chloride, add 2 g of composite material, stir at room temperature for 3 h, and then determine the aluminum chloride concentration in the filtrate by ICP-AES. The removal rate was calculated to be 72%.

[0078] Comparative analysis: Compared with the 93% removal rate in Example 1, the removal rate of the composite material using only hydrogen bond donors was lower (72% vs 93%), demonstrating that the synergistic effect of hydrogen bond acceptors and hydrogen bond donors in DES is crucial to improving the adsorption performance of aluminum chloride.

[0079] Comparative Example 3 This comparative example provides a composite material that uses only hydrogen bond acceptors, and its preparation method is as follows: 10g of UiO-66 was placed in 40g of toluene and ultrasonically dispersed for 45 minutes to form a suspension. Grafting reagent (6g of γ-aminopropyltriethoxysilane and 4g of bismaleimide) was added, and the mixture was reacted at 65℃ for 30h to obtain surface-modified UiO-66. 5g of the modified UiO-66 was added to a solution containing only hydrogen bond acceptors (choline chloride, concentration 0.4g / mL), impregnated at 45℃ for 20h, and dried at 50℃ for 5h to obtain the MOF-DES composite material.

[0080] Aluminum chloride removal test: Prepare 100 mL of simulated PAO solution containing 10 g / L aluminum chloride, add 2 g of composite material, stir at room temperature for 3 h, and then determine the aluminum chloride concentration in the filtrate by ICP-AES. The removal rate was calculated to be 75%.

[0081] Comparative analysis: Compared with the 93% removal rate in Example 1, the removal rate of the composite material using only hydrogen bond acceptors was lower (75% vs 93%), further demonstrating the necessity of the synergistic effect of hydrogen bond acceptors and hydrogen bond donors in DES to improve the adsorption performance of aluminum chloride.

[0082] The above comparative examples, through comparative experimental data, powerfully illustrate that the technical solution of this invention, which involves "first modifying the surface of MOF with a specific grafting reagent and then immobilizing a complete DES system," produces unexpected synergistic effects and technological advancements compared to "simple physical mixing" or "using a single component of DES." This significantly improves the adsorption performance and stability of the composite material for aluminum chloride, thus fully demonstrating the inventiveness and industrial applicability of this invention.

[0083] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A method for preparing a composite material for separating aluminum chloride catalyst from PAO, characterized in that, include: MOF material and organic solvent are mixed to obtain a suspension, then grafting reagent is added and heated to react. Solid-liquid separation and drying are performed to obtain MOF material with surface modified with grafting reagent. The MOF material with the grafted reagent on its surface is added to a solution containing a deep eutectic solvent, and then impregnated, separated from solids, and dried to obtain a composite material for separating aluminum chloride catalyst in PAO.

2. The method for preparing the composite material for separating aluminum chloride catalyst in PAO as described in claim 1, characterized in that, The MOF material is selected from one or more of UiO-66, MIL-101, and ZIF-8.

3. The method for preparing the composite material for separating aluminum chloride catalyst in PAO as described in claim 1, characterized in that, The organic solvent is selected from one or more of toluene, xylene, ethylbenzene, acetone, ethyl acetate, tetrahydrofuran, and dimethylformamide.

4. The method for preparing the composite material for separating aluminum chloride catalyst in PAO as described in claim 1, characterized in that, The mass ratio of the organic solvent to the MOF material is 2-5:

1.

5. The method for preparing the composite material for separating aluminum chloride catalyst from PAO as described in claim 1, characterized in that, The grafting reagent includes a silane coupling agent and an organic crosslinking agent. The silane coupling agent is selected from one or more of γ-aminopropyltriethoxysilane, epoxysilane, vinylsilane, methacryloxysilane, and γ-glycidoxypropyltrimethoxysilane. The organic crosslinking agent is selected from one or more of glutaraldehyde, hexamethylenediamine, bismaleimide, melamine-formaldehyde resin, epoxy resin, and dicumyl peroxide.

6. The method for preparing the composite material for separating aluminum chloride catalyst in PAO as described in claim 5, characterized in that, The mass ratio of the silane coupling agent to the organic crosslinking agent is 1-3:1; And / or, The mass ratio of the grafting reagent to the MOF material is 0.2-1:

1.

7. The method for preparing the composite material for separating aluminum chloride catalyst in PAO as described in claim 1, characterized in that, The heating reaction is carried out at a temperature of 40-80℃ for 2-48 hours.

8. The method for preparing the composite material for separating aluminum chloride catalyst in PAO as described in claim 1, characterized in that, The deep eutectic solvent includes one or more of the following: choline chloride and ethylene glycol, urea and malonic acid, betaine and glycerol, choline chloride and glycerol, urea and malic acid, and betaine and xylitol.

9. The method for preparing the composite material for separating aluminum chloride catalyst in PAO according to any one of claims 1-8, characterized in that, The mass ratio of the deep eutectic solvent to the MOF material is 0.1-1:1; And / or, The immersion temperature is 30-70℃, and the time is 12-24h.

10. A composite material for separating aluminum chloride catalyst from PAO, characterized in that, It was prepared using the method for preparing the composite material for separating aluminum chloride catalyst in PAO according to any one of claims 1-9.

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