Silicon element directional trapping agent for silicon-containing organic waste gas as well as preparation method and application of silicon element directional trapping agent

Abstract

The invention discloses a silicon element directional trapping agent for silicon-containing organic waste gas as well as a preparation method and application thereof, and relates to the technical field of waste gas separation. The trapping agent is prepared from the following raw materials in parts by weight: 30 to 60 parts of attapulgite, 20 to 30 parts of sepiolite powder, 6 to 19.2 parts of modified mesoporous titanium dioxide, 3 to 8 parts of 1-butyl-3-methylimidazolium tetrafluoroborate, 4.2 to 6.2 parts of beta-cyclodextrin, 3 to 4 parts of 3-aminopropyltrimethoxysilane, 3.6 to 11.8 parts of aluminum hydroxide, 3 to 8 parts of sodium tetraborate, 2 to 3 parts of an interface agent and 5 to 10 parts of a binding agent. According to the application, directional trapping of the silicon element in the silicon-containing organic waste gas can be realized, and heat storage ceramic blockage caused by silicon dioxide aggregation is improved.

Description

Technical Field

[0001] This application relates to the field of waste gas separation technology, and in particular to a silicon-oriented trapping agent for silicon-containing organic waste gas, its preparation method, and its application. Background Technology

[0002] Regenerative thermal oxidizers (RTOs) are one of the most widely used technologies for treating industrial organic waste gas. Their core principle is to decompose volatile organic compounds (VOCs) into carbon dioxide and water through high-temperature oxidation (typically 760℃~870℃), and utilize regenerative ceramics to achieve efficient heat recovery, achieving a thermal efficiency of over 90%. They offer advantages such as stable operation, high treatment efficiency, and relatively low energy consumption, and are widely used in industries such as spraying, chemicals, and electronics. However, when RTO systems are used to treat silicon-containing organic waste gas, the silicon in the organic matter is converted into silicon dioxide during the high-temperature oxidation process. Silica readily combines chemically with or physically deposits aluminosilicate components on the surface of the regenerative ceramics, leading to crystallization and growth within the ceramic pores, ultimately causing blockage. In the early stages of blockage, the system pressure drop increases significantly, and the fan energy consumption increases substantially. As the blockage worsens, the system's exhaust capacity decreases, potentially even triggering an emergency shutdown of the RTO, severely impacting normal production operations.

[0003] To address the aforementioned issues, the following measures are currently being taken: First, using regenerative ceramics with high silica content to slow down the silica deposition rate; second, optimizing the ceramic loading method to reduce localized blockages; and third, abandoning the regenerative structure and adopting a direct-fired thermal oxidizer. However, these solutions all have significant limitations: silica-resistant ceramics can only slow down the blockage process and cannot reduce silica formation at the source; optimizing the ceramic loading method can only alleviate blockages locally and still requires frequent cleaning or replacement, resulting in high maintenance costs; while direct-fired thermal oxidizers avoid the blockage problem of regenerative ceramics, their lack of heat recovery structure leads to a significant decrease in thermal efficiency and a significant increase in operating costs.

[0004] Therefore, there is an urgent need to develop a special material that can efficiently capture silicon elements in silicon-containing organic matter at the front end of a regenerative combustion furnace, thereby reducing the generation of silica at the source and fundamentally solving the problem of blockage in regenerative ceramics. Summary of the Invention

[0005] To improve the capture effect of silicon and solve the problem of heat storage ceramic blockage caused by silicon dioxide accumulation, this application provides a silicon-oriented capture agent for silicon-containing organic waste gas, its preparation method, and its application.

[0006] In a first aspect, this application provides a silicon-oriented trapping agent for silicon-containing organic waste gas, employing the following technical solution: A silicon-oriented trapping agent for silicon-containing organic waste gas comprises the following raw materials in parts by weight: attapulgite 30-60 parts, sepiolite powder 20-30 parts, modified mesoporous titanium dioxide 6-19.2 parts, 1-butyl-3-methylimidazolium tetrafluoroborate 3-8 parts, β-cyclodextrin 4.2-6.2 parts, 3-aminopropyltrimethoxysilane 3-4 parts, aluminum hydroxide 3.6-11.8 parts, sodium tetraborate 3-8 parts, interface agent 2-3 parts, and binder 5-10 parts.

[0007] By adopting the above technical solution, this application achieves the targeted capture of silicon elements in silicon-containing organic waste gas by constructing a multi-element synergistic system of "mineral substrate-ionic liquid-cyclodextrin-metal oxide". Among them, attapulgite and sepiolite powder can form a hierarchical porous framework, providing a high specific surface area and achieving the initial enrichment of siloxanes; modified mesoporous titanium dioxide provides Lewis acidic active centers; 1-butyl-3-methylimidazolium tetrafluoroborate enhances selective adsorption through the specific interaction between its fluoroborate anion and siloxanes; 3-aminopropyltrimethoxysilane can anchor β-cyclodextrin in the pores, and utilize its cavity structure to achieve molecular sieving and inclusion of linear / cyclic siloxanes; aluminum hydroxide and sodium tetraborate form an Al-OB network structure during calcination to generate synergistic chemical complexation sites; and the interfacial agent ensures the compatibility of the organic-inorganic interface. The above components solve the problems of low capture efficiency and poor selectivity of single materials through multiple synergistic mechanisms of physical adsorption, chemical complexation, host-guest inclusion and ionic liquid dissolution, and achieve efficient and directional capture of silicon in waste gas under room temperature conditions.

[0008] Optionally, the method for preparing the modified mesoporous titanium dioxide includes: mixing cerium nitrate hexahydrate and deionized water, adding mesoporous titanium dioxide, ultrasonically dispersing, heating and allowing to stand to precipitate, filtering, and drying to obtain modified mesoporous titanium dioxide.

[0009] By adopting the above technical solution, this application introduces rare earth metal cerium into the mesoporous titanium dioxide framework through impregnation. After ultrasonic dispersion and static precipitation treatment, cerium nitrate hexahydrate is uniformly loaded on the surface and in the pores of titanium dioxide. Utilizing the variable valence characteristics of cerium, a Ce-O-Ti heterostructure is formed with titanium dioxide. On the one hand, this increases the density of Lewis acid sites on the surface of mesoporous titanium dioxide, enhancing its affinity and coordination ability for oxygen atoms in siloxanes. On the other hand, by modulating the band structure of titanium dioxide through cerium doping, mild catalytic ring-opening or polarization of siloxanes can be induced during the capture process, thereby significantly improving the selective adsorption rate and saturated adsorption capacity of the capture agent for siloxanes in silicon-containing organic waste gas.

[0010] Optionally, the weight ratio of 1-butyl-3-methylimidazolium tetrafluoroborate to modified mesoporous titanium dioxide is 1:(2-4).

[0011] By employing the above technical solution, this application uses a specific ratio of 1-butyl-3-methylimidazolium tetrafluoroborate and modified mesoporous titanium dioxide, which ensures that the ionic liquid can achieve uniform loading on the surface and within the pores of the modified mesoporous titanium dioxide. This avoids pore blockage or active site burial caused by excessive ionic liquid, while ensuring the specific interaction between sufficient fluoroborate anions and siloxanes. Based on this, the Lewis acidic sites provided by the modified mesoporous titanium dioxide form a highly efficient coupling with the dissolution and absorption mechanism of the ionic liquid, constructing a relay capture mode of "interfacial adsorption-liquid phase dissolution." This significantly improves the directional capture efficiency and saturated capture capacity of silicon elements in silicon-containing organic waste gas while maintaining the material's high specific surface area.

[0012] Optionally, the weight ratio of the β-cyclodextrin to 3-aminopropyltrimethoxysilane is (1.4-1.8):1.

[0013] By adopting the above technical solution, this application utilizes a specific ratio of β-cyclodextrin and 3-aminopropyltrimethoxysilane to achieve efficient immobilization of cyclodextrin on a mineral substrate. Specifically, 3-aminopropyltrimethoxysilane chemically anchors β-cyclodextrin uniformly within the pores, fully exposing the hydrophobic interior of the β-cyclodextrin. This allows for the specific recognition and encapsulation of linear and cyclic siloxanes in the waste gas, successfully introducing molecular recognition functionality into the inorganic framework of the trapping agent, significantly improving the directional trapping selectivity and adsorption efficiency for silicon.

[0014] Optionally, the weight ratio of aluminum hydroxide to sodium tetraborate is (1.2-2):1.

[0015] By employing the above technical solution, this application utilizes a specific ratio of aluminum hydroxide and sodium tetraborate, which allows for a complete solid-phase reaction during calcination, forming a continuous and dense Al-OB network structure. This network can specifically complex with silanol groups through aluminum oxide clusters, and also enhances its affinity for oxygen atoms in siloxanes through the polar characteristics of boron-oxygen bonds. This constructs a highly efficient chemisorption interface within the pores of the trapping agent, significantly improving the directional trapping selectivity and complexation stability of silicon in silicon-containing organic waste gas.

[0016] Optionally, the particle size of the attapulgite is 5-15 μm, and the particle size of the sepiolite powder is 0.5-2 μm.

[0017] By adopting the above technical solution, this application controls the particle size of attapulgite to 5-15 μm, allowing it to serve as a skeleton support material, constructing the basic pore structure of the trap and providing mechanical strength. Sepiolite powder, with a particle size of 0.5-2 μm, fills the gaps in the attapulgite skeleton, increasing the bulk density to reduce large-size defects. Furthermore, its fibrous structure forms abundant micropores on the skeleton surface and in the gaps. This synergistic combination of particle sizes enables the trap to form a multi-level gradient pore structure transitioning from macropores (built by attapulgite) to mesopores / micropores (filled by sepiolite powder and its own structure). This ensures smooth diffusion and mass transfer of waste gas within the trap, significantly increases the specific surface area and the exposure of active sites, and is beneficial for improving the trapping efficiency of silicon in silicon-containing organic waste gas.

[0018] Optionally, the binder includes aluminum phosphate sol and silica sol.

[0019] By adopting the above technical solution, this application uses a combination of aluminum phosphate sol and silica sol as a binder. The two play a synergistic role in the formation of the trap: the inorganic bonding bridge phase formed after the aluminum phosphate sol is cured can provide good initial bonding strength and heat resistance stability for the trap particles, preventing the porous skeleton from collapsing during calcination or use; the silica sol forms a Si-O-Si network structure rich in silanols after drying and curing. On the one hand, it fills the gaps between particles to enhance the overall mechanical strength, and on the other hand, the silanols exposed on its surface can synergistically participate in the adsorption of siloxanes in silicon-containing organic waste gas.

[0020] Optionally, the interface agent is γ-aminopropyltriethoxysilane.

[0021] By adopting the above technical solution, γ-aminopropyltriethoxysilane is selected as the interface agent. Its molecular structure contains both triethoxy groups that can undergo condensation reactions with the hydroxyl groups on the surface of inorganic fillers and amino functional groups that can interact with organic components. During the preparation of the trapping agent, after hydrolysis, the triethoxy groups can form covalent bonds with the hydroxyl groups on the surface of inorganic materials such as attapulgite, sepiolite powder, and modified mesoporous titanium dioxide, effectively bridging the inorganic particles with organic components (such as β-cyclodextrin and ionic liquids), significantly improving the compatibility and bonding strength of the organic-inorganic interface. At the same time, its terminal amino functional groups can not only participate in the coordination of silicon atoms in the siloxane, but also form hydrogen bond networks with other oxygen-containing functional groups in the system, further enhancing the structural integrity and synergistic effect of each component of the trapping agent. Through the interfacial modification and functional bridging effect of this coupling agent, the trapping agent can maintain structural stability during multiple adsorption-regeneration processes, effectively preventing the loss of active components, thereby improving the long-term effectiveness and recycling stability of silicon element capture in silicon-containing organic waste gas.

[0022] Secondly, this application provides a method for preparing a silicon-oriented precipitant for silicon-containing organic waste gas, employing the following technical solution: A method for preparing a silicon-oriented trapping agent for silicon-containing organic waste gas includes the following steps: S1. Mix 3-aminopropyltrimethoxysilane with the first solvent, add attapulgite and sepiolite powder, heat to react, and obtain the modified mineral. S2. Mix β-cyclodextrin and the second solvent, add to the modified mineral, heat to react, then add 1-butyl-3-methylimidazolium tetrafluoroborate, impregnate, dry, and obtain the functionalized carrier; S3. Mix modified mesoporous titanium dioxide, aluminum hydroxide and sodium tetraborate, add deionized water, stir evenly to obtain a mixed slurry; S4. Add the functionalized carrier to the mixed slurry, heat it, add the interface agent and binder in sequence, stir evenly, granulate, dry, calcine and activate to obtain a silicon-oriented trapping agent for silicon-containing organic waste gas.

[0023] Optionally, the first solvent is an ethanol solution.

[0024] Optionally, the second solvent is N,N-dimethylformamide.

[0025] Optionally, in step S1, the heating temperature is 60-80℃.

[0026] Optionally, in step S2, the heating reaction temperature is 80-100℃ and the drying temperature is 60-80℃.

[0027] Optionally, in step S3, the stirring speed is 400-600 rpm.

[0028] Optionally, in step S4, the heating temperature is 50-60℃, the stirring speed is 600-800 rpm, the drying temperature is 80-120℃, and the calcination temperature is 400-500℃.

[0029] Thirdly, this application provides the application of a silicon-oriented trapping agent for silicon-containing organic waste gas in the treatment of silicon-containing organic waste gas.

[0030] In summary, this application includes at least one of the following beneficial technical effects: 1. This application achieves the targeted capture of silicon elements in silicon-containing organic waste gas by constructing a multi-element synergistic system of "mineral substrate-ionic liquid-cyclodextrin-metal oxide". Among them, attapulgite and sepiolite powder can form a hierarchical porous framework, providing a high specific surface area and achieving the initial enrichment of siloxanes; modified mesoporous titanium dioxide provides Lewis acidic active centers; 1-butyl-3-methylimidazolium tetrafluoroborate enhances selective adsorption through the specific interaction between its fluoroborate anion and siloxanes; 3-aminopropyltrimethoxysilane can anchor β-cyclodextrin in the pores, and utilize its cavity structure to achieve molecular sieving and inclusion of linear / cyclic siloxanes; aluminum hydroxide and sodium tetraborate form an Al-OB network structure during calcination to generate synergistic chemical complexation sites; and the interfacial agent ensures the compatibility of the organic-inorganic interface; the above components solve the problems of low capture efficiency and poor selectivity of single materials through multiple synergistic mechanisms of physical adsorption, chemical complexation, host-guest inclusion and ionic liquid dissolution, and achieve efficient and directional capture of silicon in waste gas under room temperature conditions; 2. This application introduces rare earth metal cerium into the mesoporous titanium dioxide framework via impregnation. After ultrasonic dispersion and static precipitation, cerium nitrate hexahydrate is uniformly loaded on the surface and within the pores of titanium dioxide. Utilizing the variable valence characteristics of cerium, a Ce-O-Ti heterostructure is formed with titanium dioxide. On the one hand, this increases the density of Lewis acid sites on the surface of mesoporous titanium dioxide, enhancing its affinity and coordination ability for oxygen atoms in siloxanes. On the other hand, by modulating the band structure of titanium dioxide through cerium doping, mild catalytic ring-opening or polarization of siloxanes can be induced during the capture process, thereby significantly improving the selective adsorption rate and saturated adsorption capacity of the capture agent for siloxanes in silicon-containing organic waste gas. 3. This application employs a specific ratio of 1-butyl-3-methylimidazolium tetrafluoroborate and modified mesoporous titanium dioxide, ensuring uniform loading of the ionic liquid on the surface and within the pores of the modified mesoporous titanium dioxide. This avoids pore blockage or active site burial caused by excessive ionic liquid, while guaranteeing the specific interaction between sufficient fluoroborate anions and siloxanes. Based on this, the Lewis acidic sites provided by the modified mesoporous titanium dioxide form a highly efficient coupling with the dissolution and absorption mechanism of the ionic liquid, constructing a relay capture mode of "interfacial adsorption-liquid phase dissolution." This significantly improves the directional capture efficiency and saturated capture capacity of silicon in silicon-containing organic waste gas while maintaining the material's high specific surface area. 4. This application employs a specific ratio of β-cyclodextrin and 3-aminopropyltrimethoxysilane to achieve efficient immobilization of cyclodextrin on a mineral substrate. Specifically, 3-aminopropyltrimethoxysilane chemically anchors β-cyclodextrin uniformly within the pores, fully exposing the hydrophobic interior of the β-cyclodextrin. This allows for the specific recognition and encapsulation of linear and cyclic siloxanes in the waste gas, successfully introducing molecular recognition functionality into the inorganic framework of the trapping agent, significantly improving the directional trapping selectivity and adsorption efficiency for silicon. Detailed Implementation

[0031] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0032] This application discloses a silicon-oriented trapping agent for silicon-containing organic waste gas, comprising the following raw materials in parts by weight: attapulgite 30-60 parts, sepiolite powder 20-30 parts, modified mesoporous titanium dioxide 6-19.2 parts, 1-butyl-3-methylimidazolium tetrafluoroborate 3-8 parts, β-cyclodextrin 4.2-6.2 parts, 3-aminopropyltrimethoxysilane 3-4 parts, aluminum hydroxide 3.6-11.8 parts, sodium tetraborate 3-8 parts, interface agent 2-3 parts, and binder 5-10 parts.

[0033] This application discloses a method for preparing a silicon-oriented trapping agent for silicon-containing organic waste gas, comprising the following steps: S1. Mix 3-aminopropyltrimethoxysilane with the first solvent, add attapulgite and sepiolite powder, heat at 60-80℃ for 2-4 hours to obtain the modified mineral. S2. Mix β-cyclodextrin and the second solvent, add it to the modified mineral, react at 80-100℃ and 100-300rpm for 4-6h, then add 1-butyl-3-methylimidazolium tetrafluoroborate, impregnate for 2-3h, and dry at 60-80℃ for 6-8h to obtain the functionalized carrier. S3. Mix modified mesoporous titanium dioxide, aluminum hydroxide and sodium tetraborate, add deionized water, and stir at 400-600 rpm for 20-30 min to obtain a mixed slurry. S4. Add the functionalized carrier to the mixed slurry, heat to 50-60℃, add the interface agent and binder in sequence, stir at 600-800 rpm for 20-30 min, granulate, dry at 80-120℃ for 4-6 h, and calcine and activate at 400-500℃ for 2-4 h to obtain a silicon-oriented trapping agent for silicon-containing organic waste gas.

[0034] All raw materials used in the embodiments of this application are commercially available, wherein: Mesoporous titanium dioxide, Xi'an Qiyue Biotechnology Co., Ltd.; 3-Aminopropyltrimethoxysilane, Shanghai Aladdin Biochemical Technology Co., Ltd.; Attapulgite clay, Shenzhen Haiyang Powder Technology Co., Ltd.; Sepiolite powder, Lingshou County Hefeng Mineral Products Co., Ltd.; β-Cyclodextrin, Zibo Qianhui Biotechnology Co., Ltd.; 1-Butyl-3-methylimidazolium tetrafluoroborate, Linzhou Keneng Materials Technology Co., Ltd.; Aluminum hydroxide, Shandong Chenxu New Material Co., Ltd.; Sodium tetraborate, Shanghai Aladdin Biochemical Technology Co., Ltd.; γ-aminopropyltriethoxysilane, Shanghai Aladdin Biochemical Technology Co., Ltd.; Cerium nitrate hexahydrate, Shanghai Aladdin Biochemical Technology Co., Ltd.; Anhydrous ethanol, Shanghai Aladdin Biochemical Technology Co., Ltd.; N,N-Dimethylformamide, Shanghai Aladdin Biochemical Technology Co., Ltd.; Aluminum phosphate sol, Dalian Snow Chemical New Materials Science and Technology Co., Ltd.; Silica sol, Dalian Snow Chemical New Materials Science and Technology Co., Ltd.

[0035] Preparation Example 1 Preparation of modified mesoporous titanium dioxide: 2g of cerium nitrate hexahydrate and 100mL of deionized water were mixed, 10g of mesoporous titanium dioxide was added, ultrasonically dispersed at 500W for 20min, allowed to stand at 50℃ for 3h to precipitate, filtered, and dried at 80℃ for 12h to obtain modified mesoporous titanium dioxide.

[0036] Example 1 3g of 3-aminopropyltrimethoxysilane was mixed with 50mL of ethanol solution (a mixture of 40mL anhydrous ethanol and 10mL deionized water), and 30g of attapulgite (particle size 5-15μm) and 20g of sepiolite powder (0.5-2μm) were added. The mixture was heated at 60℃ for 4h to obtain a modified mineral. 4.2g of β-cyclodextrin and 30mL of N,N-dimethylformamide were mixed and added to the modified mineral. The mixture was reacted at 80℃ and 100rpm for 6h, and then 3g of 1-butyl-3-methylimidazolium tetrafluoroborate was added. The mixture was impregnated for 3h and dried at 60℃ for 8h to obtain a functionalized carrier. 6g of the modified mesoporous titanium dioxide obtained in Preparation Example 1, 3.6g of aluminum hydroxide, and 3g of sodium tetraborate were mixed and 50mL of deionized water were added. The mixture was stirred at 400rpm for 30min to obtain a mixed slurry. The functionalized carrier was added to the mixed slurry, the temperature was raised to 50℃, and 2g of... γ-aminopropyltriethoxysilane was stirred at 600 rpm for 30 min, 2.5 g of aluminum phosphate sol and 2.5 g of silica sol were added, stirred at 600 rpm for 10 min, granulated, dried at 80℃ for 6 h, and calcined and activated at 400℃ for 4 h to obtain a silicon-oriented trapping agent for silicon-containing organic waste gas.

[0037] Example 2 3.5 g of 3-aminopropyltrimethoxysilane was mixed with 60 mL of ethanol solution (a mixture of 50 mL of anhydrous ethanol and 10 mL of deionized water), and 45 g of attapulgite (particle size 5-15 μm) and 25 g of sepiolite powder (0.5-2 μm) were added. The mixture was heated at 70 °C for 3 h to obtain a modified mineral. 4.9 g of β-cyclodextrin and 40 mL of N,N-dimethylformamide were mixed and added to the modified mineral. The mixture was reacted at 90 °C and 200 rpm for 5 h, and then 5 g of 1-butyl-3-methylimidazolium tetrafluoroborate was added. The mixture was impregnated for 2.5 h and dried at 70 °C for 7 h to obtain a functionalized support. 10 g of the modified mesoporous titanium dioxide obtained in Preparation Example 1, 6 g of aluminum hydroxide, and 5 g of sodium tetraborate were mixed and 80 mL of deionized water were added. The mixture was stirred at 500 rpm for 25 min to obtain a mixed slurry. The functionalized support was added to the mixed slurry, the temperature was raised to 55 °C, and 2.5 g of... γ-aminopropyltriethoxysilane was stirred at 700 rpm for 25 min, and 3.75 g of aluminum phosphate sol and 3.75 g of silica sol were added. The mixture was stirred at 700 rpm for 20 min, granulated, dried at 100℃ for 5 h, and calcined at 450℃ for 3 h to obtain a silicon-oriented trapping agent for silicon-containing organic waste gas.

[0038] Example 3 4 g of 3-aminopropyltrimethoxysilane was mixed with 80 mL of ethanol solution (a mixture of 65 mL of anhydrous ethanol and 15 mL of deionized water), and 60 g of attapulgite (particle size 5-15 μm) and 30 g of sepiolite powder (0.5-2 μm) were added. The mixture was heated at 80 °C for 2 h to obtain a modified mineral. 5.6 g of β-cyclodextrin and 50 mL of N,N-dimethylformamide were mixed and added to the modified mineral. The mixture was reacted at 100 °C and 300 rpm for 4 h. Then, 8 g of 1-butyl-3-methylimidazolium tetrafluoroborate was added, and the mixture was impregnated for 2 h and dried at 80 °C for 6 h to obtain a functionalized carrier. 16 g of the modified mesoporous titanium dioxide obtained in Preparation Example 1, 9.6 g of aluminum hydroxide, and 8 g of sodium tetraborate were mixed and 100 mL of deionized water were added. The mixture was stirred at 600 rpm for 20 min to obtain a mixed slurry. The functionalized carrier was added to the mixed slurry, the temperature was raised to 60 °C, and 3 g of... γ-aminopropyltriethoxysilane was stirred at 800 rpm for 20 min, 5 g of aluminum phosphate sol and 5 g of silica sol were added, stirred at 800 rpm for 10 min, granulated, dried at 120℃ for 4 h, and calcined at 500℃ for 2 h to obtain a silicon-oriented trapping agent for silicon-containing organic waste gas.

[0039] Comparative Example 1 The difference between this comparative example and Example 3 is that the mass of 1-butyl-3-methylimidazolium tetrafluoroborate in Example 3 is replaced with modified mesoporous titanium dioxide.

[0040] Comparative Example 2 The difference between this comparative example and Example 3 is that the modified mesoporous titanium dioxide in Example 3 is replaced by 1-butyl-3-methylimidazolium tetrafluoroborate.

[0041] Comparative Example 3 The difference between this comparative example and Example 3 is that the β-cyclodextrin in Example 3 is replaced by 3-aminopropyltrimethoxysilane in this comparative example.

[0042] Comparative Example 4 The difference between this comparative example and Example 3 is that the 3-aminopropyltrimethoxysilane in Example 3 is replaced by β-cyclodextrin by mass.

[0043] The silicon-oriented trapping agents for silicon-containing organic waste gas prepared in Examples 1-3 and Comparative Examples 1-4 were tested for 5% adsorption capacity and saturation adsorption capacity. 0.8 g of the silicon-oriented trapping agent for silicon-containing organic waste gas was placed in a quartz glass tube. Methane gas with a tetraethoxysilane concentration of 50 mg / L was used as the gas to be treated. The quartz glass tube was operated at a flow rate of 80 mL / min. The adsorption capacity was measured when the siloxane concentration in the outlet gas was 5% of the inlet siloxane concentration. Adsorption ended when the siloxane concentration remained constant and approached the inlet concentration, yielding the saturation adsorption capacity.

[0044] Table 1 Performance of silicon-oriented traps for silicon-containing organic waste gases in Examples 1-3 and Comparative Examples 1-4

[0045] As shown in Examples 1-3 and Table 1, the 5% adsorption capacity of the silicon-oriented trapping agent for silicon-containing organic waste gas in Examples 1-3 of this application is above 82.1 mg / L, and the saturated adsorption capacity is above 102.7 mg / L. This indicates that this application can achieve the directional trapping of silicon in silicon-containing organic waste gas by constructing a multi-element synergistic system of "mineral substrate-ionic liquid-cyclodextrin-metal oxide".

[0046] As shown in Example 3, Comparative Examples 1-2, and Table 1, the 5% adsorption capacity of the silicon-oriented trapping agent for silicon-containing organic waste gas in Example 3 of this application is 87.3 mg / L, and the saturated adsorption capacity is 108.9 mg / L, which is significantly better than that in Comparative Examples 1-2. This indicates that this application constructs a relay trapping mode of "interfacial adsorption-liquid phase dissolution" through the synergistic effect of 1-butyl-3-methylimidazolium tetrafluoroborate and modified mesoporous titanium dioxide, which significantly improves the adsorption capacity of silicon. Compared with Example 3, although the modified mesoporous titanium dioxide in Comparative Example 1 can provide a certain amount of Lewis acidic active centers, its adsorption capacity for siloxanes is weak, resulting in a significant decrease in trapping efficiency. Compared with Example 3, although the simple 1-butyl-3-methylimidazolium tetrafluoroborate in Comparative Example 2 can provide a certain solubility and absorption capacity through the specific interaction between its fluoroborate anion and siloxane, it lacks the support of mesoporous structure. The ionic liquid is difficult to achieve uniform dispersion and stable immobilization in the trapping agent, and is prone to loss or aggregation, resulting in insufficient exposure of active sites and thus reduced adsorption performance.

[0047] As shown in Example 3, Comparative Examples 3-4, and Table 1, the 5% adsorption capacity of the silicon-oriented trapping agent for silicon-containing organic waste gas in Example 3 of this application is 87.3 mg / L, and the saturated adsorption capacity is 108.9 mg / L, which is significantly better than that in Comparative Examples 3-4. This indicates that the synergistic effect of β-cyclodextrin and 3-aminopropyltrimethoxysilane in this application achieves efficient immobilization and molecular recognition of cyclodextrin on mineral substrates. Compared with Example 3, although the simple 3-aminopropyltrimethoxysilane in Comparative Example 3 can be used as a coupling agent to modify the surface of attapulgite and sepiolite powder and improve the interfacial compatibility between inorganic minerals and organic components, its trapping selectivity and adsorption efficiency are low due to the coordination effect of amino groups and the physical adsorption on the mineral surface alone. Compared with Example 3, although the simple β-cyclodextrin in Comparative Example 3 can utilize its hydrophobic cavity to perform host-guest inclusion of siloxanes and provide a certain molecular recognition and physical capture ability, the interfacial binding force between β-cyclodextrin and the inorganic mineral framework is weak, and it cannot form a stable functionalized carrier structure, resulting in a significant reduction in adsorption performance.

[0048] Examples 4-5 Based on Example 3, except for the weight ratio of 1-butyl-3-methylimidazolium tetrafluoroborate and modified mesoporous titanium dioxide, the other components and preparation methods are the same as in Example 3, and the total weight of 1-butyl-3-methylimidazolium tetrafluoroborate and modified mesoporous titanium dioxide remains unchanged.

[0049] Example 4 The difference between this embodiment and Embodiment 3 is that the weight ratio of 1-butyl-3-methylimidazolium tetrafluoroborate and modified mesoporous titanium dioxide in this embodiment is 1:3. Specifically, the weight of 1-butyl-3-methylimidazolium tetrafluoroborate is 6g and the weight of modified mesoporous titanium dioxide is 18g.

[0050] Example 5 The difference between this embodiment and Embodiment 3 is that the weight ratio of 1-butyl-3-methylimidazolium tetrafluoroborate and modified mesoporous titanium dioxide in this embodiment is 1:4. Specifically, the weight of 1-butyl-3-methylimidazolium tetrafluoroborate is 4.8g and the weight of modified mesoporous titanium dioxide is 19.2g.

[0051] Examples 6-7 Based on Example 4, except for the weight ratio of β-cyclodextrin and 3-aminopropyltrimethoxysilane, the other components and preparation methods are the same as in Example 4, and the total weight of β-cyclodextrin and 3-aminopropyltrimethoxysilane remains unchanged.

[0052] Example 6 The difference between this embodiment and Embodiment 4 is that the weight ratio of β-cyclodextrin to 3-aminopropyltrimethoxysilane in this embodiment is 1.6:1. Specifically, the weight of β-cyclodextrin is 5.9g and the weight of 3-aminopropyltrimethoxysilane is 3.7g.

[0053] Example 7 The difference between this embodiment and Example 4 is that the weight ratio of β-cyclodextrin to 3-aminopropyltrimethoxysilane in this embodiment is 1.8:1. Specifically, the weight of β-cyclodextrin is 6.17g and the weight of 3-aminopropyltrimethoxysilane is 3.43g.

[0054] Examples 8-9 Based on Example 6, except for the weight ratio of aluminum hydroxide and sodium tetraborate, the other components and preparation methods are the same as in Example 6, and the total weight of aluminum hydroxide and sodium tetraborate remains unchanged.

[0055] Example 8 The difference between this embodiment and embodiment 6 is that the weight ratio of aluminum hydroxide to sodium tetraborate in this embodiment is 1.5:1. Specifically, the weight of aluminum hydroxide is 10.56g and the weight of sodium tetraborate is 7.04g.

[0056] Example 9 The difference between this embodiment and Embodiment 6 is that the weight ratio of aluminum hydroxide to sodium tetraborate in this embodiment is 2:1. Specifically, the weight of aluminum hydroxide is 11.73g and the weight of sodium tetraborate is 5.87g.

[0057] Performance Test 2 The silicon-oriented trapping agents for silicon-containing organic waste gas prepared in Examples 4-9 were tested for 5% adsorption capacity and saturated adsorption capacity. The test methods were the same as those in Performance Test 1, and the test results are shown in Table 2 below.

[0058] Table 2 Performance of silicon-oriented traps for silicon-containing organic waste gases in Examples 3-9

[0059] As shown in Examples 3-5 and Table 2, the 5% adsorption capacity of the silicon-oriented trapping agent for silicon-containing organic waste gas in Example 4 of this application is 96.2 mg / L, and the saturated adsorption capacity is 141.5 mg / L, which is significantly better than that in Examples 3 and 5. This indicates that the specific ratio of 1-butyl-3-methylimidazolium tetrafluoroborate and modified mesoporous titanium dioxide used in this application allows for a more uniform loading of ionic liquid on the surface of mesoporous titanium dioxide, avoiding pore blockage and enhancing the relay trapping efficiency of "interfacial adsorption-liquid phase dissolution". Compared to Example 4, the excessively high proportion of 1-butyl-3-methylimidazolium tetrafluoroborate in Example 3 leads to the formation of multiple layers of coverage and even pore blockage on the surface and within the pores of the modified mesoporous titanium dioxide, preventing the efficient transport of siloxane to the ionic liquid phase and reducing the overall trapping efficiency. Compared to Example 4, the excessively high proportion of modified mesoporous titanium dioxide in Example 5 affects the directional selectivity of the trapping agent for silicon.

[0060] As shown in Examples 4, 6-7, and Table 2, the 5% adsorption capacity of the silicon-oriented trapping agent for silicon-containing organic waste gas in Example 6 of this application is 98.4 mg / L, and the saturated adsorption capacity is 152.8 mg / L, which is significantly better than that in Examples 4 and 7. This indicates that the specific ratio of β-cyclodextrin and 3-aminopropyltrimethoxysilane used in this application enables more efficient immobilization of β-cyclodextrin within the mineral pores, fully exposing the cavity structure and significantly enhancing the host-guest inclusion effect. Compared to Example 6, the excessively high proportion of 3-aminopropyltrimethoxysilane in Example 4 leads to over-occupation of reactive hydroxyl sites on the mineral surface. Excess silane molecules are prone to self-polymerization and condensation, forming oligomers or localized enrichment zones, resulting in a decrease in the uniformity of β-cyclodextrin distribution within the pores, and consequently a decrease in adsorption kinetics and a reduction in the 5% adsorption capacity. Compared to Example 6, the excessively high proportion of β-cyclodextrin in Example 4 not only prevents the aggregates from performing molecular recognition functions, but also physically blocks the mesoporous and microporous channels of the mineral framework, resulting in a decrease in the accessibility of host-guest inclusion interactions, ultimately manifested as a simultaneous decrease in adsorption capacity and adsorption rate.

[0061] As shown in Examples 6, 8-9, and Table 2, the 5% adsorption capacity of the silicon-oriented trapping agent for silicon-containing organic waste gas in Example 8 of this application is 99.2 mg / L, and the saturated adsorption capacity is 158.5 mg / L, which is significantly better than that in Examples 6 and 9. This indicates that the specific ratio of aluminum hydroxide and sodium tetraborate used in this application makes the Al-OB network structure formed during the roasting process more continuous and dense, with richer chemical complexation sites, significantly improving the trapping selectivity and complexation stability. Compared to Example 8, the excessively high proportion of sodium tetraborate in Example 6 leads to the formation of a boron-rich phase, resulting in a reduction in the number of effective chemical complexation sites and a decrease in trapping selectivity. Compared to Example 8, the excessively high proportion of aluminum hydroxide in Example 9 leads to a decrease in its complexation ability for siloxanes, thereby reducing both the affinity and selectivity of the trapping agent for siloxanes.

[0062] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A silicon-oriented trapping agent for silicon-containing organic waste gas, characterized in that, The raw materials include the following parts by weight: attapulgite 30-60 parts, sepiolite powder 20-30 parts, modified mesoporous titanium dioxide 6-19.2 parts, 1-butyl-3-methylimidazolium tetrafluoroborate 3-8 parts, β-cyclodextrin 4.2-6.2 parts, 3-aminopropyltrimethoxysilane 3-4 parts, aluminum hydroxide 3.6-11.8 parts, sodium tetraborate 3-8 parts, interface agent 2-3 parts, and binder 5-10 parts; The method for preparing the modified mesoporous titanium dioxide includes: mixing cerium nitrate hexahydrate and deionized water, adding mesoporous titanium dioxide, ultrasonically dispersing, heating and allowing it to stand to precipitate, filtering, and drying to obtain modified mesoporous titanium dioxide.

2. The silicon-oriented trapping agent for silicon-containing organic waste gas according to claim 1, characterized in that, The weight ratio of 1-butyl-3-methylimidazolium tetrafluoroborate to modified mesoporous titanium dioxide is 1:(2-4).

3. The silicon-oriented trapping agent for silicon-containing organic waste gas according to claim 1, characterized in that, The weight ratio of the β-cyclodextrin to 3-aminopropyltrimethoxysilane is (1.4-1.8):

1.

4. The silicon-oriented trapping agent for silicon-containing organic waste gas according to claim 1, characterized in that, The weight ratio of aluminum hydroxide to sodium tetraborate is (1.2-2):

1.

5. The silicon-oriented trapping agent for silicon-containing organic waste gas according to claim 1, characterized in that, The attapulgite has a particle size of 5-15 μm, and the sepiolite powder has a particle size of 0.5-2 μm.

6. The silicon-oriented trapping agent for silicon-containing organic waste gas according to claim 1, characterized in that, The binder includes aluminum phosphate sol and silica sol.

7. The silicon-oriented trapping agent for silicon-containing organic waste gas according to claim 1, characterized in that, The interface agent is γ-aminopropyltriethoxysilane.

8. A method for preparing a silicon-oriented trapping agent for silicon-containing organic waste gas according to any one of claims 1-7, characterized in that, Includes the following steps: S1. Mix 3-aminopropyltrimethoxysilane with the first solvent, add attapulgite and sepiolite powder, heat to react, and obtain the modified mineral. S2. Mix β-cyclodextrin and the second solvent, add to the modified mineral, heat to react, then add 1-butyl-3-methylimidazolium tetrafluoroborate, impregnate, dry, and obtain the functionalized carrier; S3. Mix modified mesoporous titanium dioxide, aluminum hydroxide and sodium tetraborate, add deionized water, stir evenly to obtain a mixed slurry; S4. Add the functionalized carrier to the mixed slurry, heat it, add the interface agent and binder in sequence, stir evenly, granulate, dry, calcine and activate to obtain a silicon-oriented trapping agent for silicon-containing organic waste gas.

9. The application of a silicon-oriented trapping agent for silicon-containing organic waste gas according to any one of claims 1-7 in the treatment of silicon-containing organic waste gas.

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