Flexible silicon dioxide composite aerogel adsorption material without powder falling

Abstract

The invention discloses a non-dusting flexible silicon dioxide composite aerogel adsorption material which is formed by in-situ compounding of SiO2 aerogel and a carbon aerogel material, is used for filtering a cigarette holder adsorption material and can effectively adsorb harmful substances in cigarette smoke. Wherein the mass ratio of the silicon dioxide aerogel to the carbon aerogel is 1: (0.1-0.3). The silicon dioxide aerogel and the high-porosity macroporous structure nitrogen-containing carbon aerogel are subjected to in-situ doping, compounding and drying to form the material, the material combines the adsorption performance of the silicon dioxide aerogel and the adsorption performance of the carbon aerogel, and compared with traditional silicon dioxide aerogel, the material is high in porosity, rich in pore channel structure and not prone to powder falling, and the material has the advantages of being simple in preparation process, low in cost and the like. Harmful substances such as aldehydes, carbon monoxide and tar in smoke can be fully adsorbed and degraded, and the inhalation and exhalation resistance is small; compared with a common adsorbent for cigarettes in the prior art, the adsorbent has the advantages of good adsorption capacity, lower cost, simple preparation process, easiness in operation and the like.

Description

Technical Field

[0001] This invention relates to the field of aerogel adsorption filtration technology, specifically to a non-shedding flexible silica composite aerogel adsorption material, specifically used as a cigarette filter adsorption material. Background Technology

[0002] Cigarette smoke contains thousands of chemical substances, including tar, aldehydes, carbon monoxide, and nicotine. Many of these components are significantly harmful to the human respiratory and cardiovascular systems. Long-term smoking increases the risk of various diseases, and secondhand smoke also has adverse effects on the health of non-smokers. Effectively reducing the harmful components in cigarette smoke while maintaining a pleasant smoking experience has always been a core research focus for the global tobacco industry.

[0003] Currently, the most direct and widely used method for reducing harmful substances in cigarette smoke is to add adsorbent materials to cigarette filters. Traditional filters primarily use polymers such as cellulose diacetate and polypropylene fiber. However, the former suffers from limited raw material sources, complex manufacturing processes, and high costs, while the latter has a weak adsorption capacity for harmful substances, making it difficult to meet the harm reduction requirements of high-end cigarettes. While adding conventional adsorbents such as activated carbon can achieve some adsorption of harmful substances, it significantly increases the draw resistance of cigarette smoke, leading to poor vaping and severely impacting the taste and user experience. Therefore, developing cigarette smoke filter materials with high filtration efficiency, low draw resistance, good stability, and safe use is a key technological breakthrough urgently needed by the cigarette industry.

[0004] Aerogels are nanoporous solid materials with a three-dimensional network-like framework structure, hailed as the lightest solid materials. With their ultra-high porosity, large specific surface area, and excellent adsorption properties, they exhibit enormous application potential in sound and heat insulation, catalyst carriers, and filtration adsorption. Hydrophobic and oleophilic aerogels, in particular, possess a natural high adsorption advantage for oily harmful substances in cigarette smoke. Among these, silica aerogels are currently the most widely researched and industrialized aerogel type. However, pure silica aerogels suffer from inherent low strength and high brittleness. In actual use with cigarette filters, this material is highly prone to cracking, breakage, and powder shedding. This not only leads to a rapid decline in adsorption performance but also causes the shed powder to enter the human body with the smoke, posing new health and safety risks and severely limiting its large-scale application in cigarette filters.

[0005] Patent CN114307953A discloses a method for preparing a silica / carbon composite aerogel material. By forming a carbon layer on the silica aerogel framework and combining it with a two-stage heat treatment process, the material's structure and composition are optimized to achieve adsorption and degradation of aldehydes and carbon monoxide in cigarette smoke. However, this material's preparation process is complex and costly, and its adsorption effect on tar is not ideal, exhibiting significant resistance and a tendency to shed powder. Patent CN113598411A uses a mixture of macroporous silica gel, carbon aerogel, and linoleic acid-modified nano-silica-based oxides as a specific adsorbent material. Through a composite filter design, general adsorption sections and specific adsorption sections are arranged in series. This material shows good adsorption effect on crotonaldehyde, but poor effect on other adsorbent materials in cigarette smoke, and also exhibits a tendency to shed powder. Patent CN113735556A discloses a silica-containing aerogel composite material, its preparation method, and its applications. This material is composed of silica-containing aerogel and fiber. This material achieves the advantage of not shedding powder, but exhibits significant resistance. Summary of the Invention

[0006] To address the aforementioned shortcomings of existing technologies, this invention provides a non-shedding flexible silica composite aerogel adsorbent material, thereby solving the problems of poor filtration effect, easy shedding of powder, and high breathing resistance when silica aerogel is used as the adsorbent material in existing cigarette filter mouthpieces, and the difficulty in simultaneously optimizing these three properties.

[0007] To achieve the above objectives, in a first aspect, the present invention provides a non-shedding flexible silica composite aerogel adsorbent material, wherein the composite aerogel adsorbent material is formed by in-situ composite of SiO2 aerogel and carbon aerogel material, and is used as a filter adsorbent material for cigarette holders, which can effectively adsorb harmful substances in cigarette smoke; wherein the mass ratio of silica aerogel to carbon aerogel is 1:(0.1~0.3).

[0008] Preferably, the carbon aerogel is prepared by the following method:

[0009] Resorcinol, formaldehyde, pore-expanding agent and tetraethyl orthosilicate are mixed evenly, then an alkaline catalyst is added to make it gel, then an alcohol solvent is added to age the gel, and then it is dried and calcined to obtain silica-carbon composite aerogel. The silica-carbon composite aerogel is placed in hydrofluoric acid or strong alkaline solution for etching, and after drying, a high porosity macroporous structure nitrogen-containing carbon aerogel is obtained.

[0010] The molar ratio of resorcinol, formaldehyde, pore expander, and tetraethyl orthosilicate is 1:2:(0.05-0.1):(0.1-0.2); the molar ratio of resorcinol to alkaline catalyst is (300-1000):1; the pore expander is hexadecyltrimethylammonium bromide or hexadecyltrimethylammonium chloride; the alkaline catalyst is one or both of ammonia or tetramethylammonium hydroxide; the solvent is one of methanol, ethanol, or propanol; the drying and calcination temperature is gradient drying, with specific drying parameters as follows: 300℃ for 0.5h, 600℃ for 0.5h, 800℃ for 1-2h, 1000℃ for 1-2h, and 1200℃ for 1-2h; the etching solution is hydrofluoric acid or one of sodium hydroxide or potassium hydroxide, with a concentration of 3-8 mol / L, an etching time of 2-10h, and an etching temperature of 25-50℃.

[0011] Preferably, the composite aerogel adsorbent material is prepared by the following method:

[0012] Step 1: Mix the silicon source, solvent, catalyst, and pore expander evenly, and stir continuously at 25℃~50℃ for 1h~4h to prepare a sol; wherein, the mass ratio of silicon source, solvent, catalyst, and pore expander is 1:(1.5-2.5):(0.4-0.7):(0.02-0.08).

[0013] Step 2: Add an alkaline catalyst to the sol prepared in Step 1 to adjust the pH to 7-8, then add carbon aerogel powder, pour it into a mold and heat to gel to obtain a wet gel material; wherein, the temperature is heated to 50-70℃.

[0014] Step 3: Place the wet gel material prepared in step 2 into an alcohol solution, and add an alkaline solution to the alcohol solution to adjust the pH value to 8~9. Age it at 55℃~75℃ for 10h~24h.

[0015] Step 4: The aged wet gel from Step 3 is dried with supercritical CO2 to obtain the composite aerogel adsorbent material.

[0016] Step 5: Dry and deodorize the composite aerogel adsorbent material obtained in Step 4.

[0017] Preferably, in step 1, the pore-expanding agent is hexadecyltrimethylammonium bromide or hexadecyltrimethylammonium chloride; the silicon source is a mixture of silane compound and silicate ester compound, wherein the silane compound is one or two of methyltrimethoxysilane, methyltriethoxysilane, trimethylmethoxysilane, dimethyldimethoxysilane, and dimethyldiethoxysilane, and the silicate ester compound is one or two of tetraethyl orthosilicate or methyl orthosilicate, and the molar ratio of silane compound to silicate ester compound is 1:(0.05~0.2); the catalyst is an aqueous solution of one or two of nitric acid, hydrochloric acid, acetic acid, sulfuric acid, or phosphoric acid, with a concentration of 0.2mol / L~1mol / L.

[0018] Preferably, in step 2, the alkaline catalyst is one or two of ammonium carbonate, ammonium acetate buffer, or urea.

[0019] Preferably, in step 3, the alcohol solution is one of methanol, ethanol, or propanol; the alkaline solution is one or two of sodium hydroxide, potassium hydroxide, or ammonia water.

[0020] Preferably, in step 4, the supercritical CO2 drying conditions are as follows:

[0021] The CO2 flow rate is 450L / h~600L / h, the drying temperature is 45℃~55℃, the drying pressure is 14.5MPa~16.5MPa, and the drying time is 3h~8h.

[0022] Preferably, the resistance value of the composite aerogel adsorption material is less than 1000 Pa, and the adsorption mass is at least 20 times the mass of the material itself.

[0023] Secondly, the present invention also provides a filter mouthpiece, wherein the filter mouthpiece contains the aforementioned non-shedding flexible silica composite aerogel adsorption material, including but not limited to its use with a metal sleeve to form a filter mouthpiece.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] 1. Addressing the common technical problems of narrow adsorption spectra and inability to simultaneously retain particulate and gaseous harmful substances in existing tobacco filter materials, this invention constructs a dual-mechanism adsorption system that combines physical and chemical adsorption through the functional complementarity of silica aerogel and nitrogen-containing carbon aerogel. By designing a silicon source molecule that combines alkylsilanes and silicates, hydrophobic alkyl groups are introduced into the three-dimensional network framework of silica, endowing the material with strong hydrophobic and oleophilic properties. Through van der Waals forces and capillary condensation, it achieves high-capacity physical retention of non-polar particulate harmful substances such as tar and nicotine in tobacco gas. The high-porosity macroporous nitrogen-containing carbon aerogel, controllably prepared through a "sol-gel-gradient calcination-etching" process, has abundant nitrogen-containing functional groups on its surface that can form hydrogen bonds and complexes with polar gaseous harmful substances such as aldehydes and carbon monoxide, achieving specific chemical adsorption. Simultaneously, the interpenetrating network structure formed by the in-situ doping composite process avoids the deactivation of adsorption sites caused by carbon aerogel agglomeration, achieving full exposure and synergistic effect of the adsorption active sites of the two materials. The material prepared by this invention can adsorb more than 20 times its own weight. The optimal embodiment has a retention rate of 92% for harmful substances such as tar, and the retention rate of all embodiments is stable at more than 81%. It breaks through the limitation of single adsorption in the prior art and realizes the simultaneous and efficient reduction of all components of harmful substances in cigarette smoke.

[0026] 2. Addressing the core safety concerns of traditional silica aerogels, such as high brittleness, easy cracking and powder shedding, and the risk of powder detachment and inhalation associated with existing powder-loaded materials, this invention constructs a triple anti-powder-shedding and toughening mechanism from the perspectives of molecular skeleton modification and structural design. By grafting flexible alkyl groups onto the rigid Si-O-Si skeleton, the degree of cross-linking and internal stress of the skeleton are reduced, endowing the material with intrinsic flexibility and compression resilience, fundamentally suppressing the possibility of powder generation due to skeleton fracture and breakage. Through in-situ doping technology in the sol-gel stage, carbon aerogel powder is uniformly anchored and encapsulated within a continuous three-dimensional silica network, forming an integral structure of "carbon phase dispersion - silicon phase continuous encapsulation," completely eliminating the risk of carbon aerogel powder detaching with flue gas. Simultaneously, a slow gelation process regulated by a weak alkali catalyst is used to construct a uniform, dense, and defect-free continuous three-dimensional skeleton, avoiding the problems of skeleton inhomogeneity and localized loose cracking caused by rapid gelation with strong alkali, further ensuring the structural integrity of the material. Compared with the control group that did not undergo alkyl modification and rapid gelation, the monolithic aerogel materials prepared by this invention showed no cracking or powder shedding, completely eliminating the safety hazard of powder shedding in tobacco use scenarios, while also possessing excellent flexibility and processability.

[0027] 3. To address the inherent technical contradiction of traditional filter materials where "the higher the adsorption efficiency, the greater the flue gas resistance," this invention achieves a precise balance between adsorption performance and flow performance through a two-stage pore-expanding process and an integral through-channel design. Pore ​​expanders were introduced simultaneously in both the carbon aerogel preparation and silica sol formulation stages to construct a hierarchical pore structure of "macropores for airflow and mesopores / micropores for adsorption." The micron-sized macropores of the carbon aerogel, formed by etching, provide low-resistance, unobstructed flow channels for flue gas, significantly reducing its flow resistance. Meanwhile, the precise control of mesopores and micropores in the silica aerogel provides sufficient active sites for the adsorption of harmful substances, ensuring full contact between the flue gas and the adsorption sites without obstructing the flow of flue gas due to excessively narrow pores. At the same time, the integral three-dimensional network structure avoids the problems of pore blockage and pore tortuosity caused by powder filling, allowing flue gas to pass uniformly along the continuous, unobstructed pores without local turbulence or flow bottlenecks. The low-crosslinking flexible framework ensures the stability of the pore structure during suction, avoiding the continuous increase in suction resistance caused by structural damage in traditional rigid aerogels. The cigarette holder made of the composite aerogel adsorption material described in this invention has a resistance value of less than 1000 Pa, which fully meets the low resistance requirement for cigarette smoking. This is in stark contrast to the comparison of cigarettes without pore-expanding agents, where the draw resistance soars to 4310 Pa. This invention truly achieves a perfect balance between high harmful substance retention rate and low draw resistance.

[0028] 4. In view of the technical problems of cumbersome preparation process, strict process parameters, high raw material cost and difficulty in large-scale scale-up of existing high-performance aerogel materials, the process route design of this invention fully takes into account both technical innovation and industrial feasibility. This invention employs an in-situ one-step composite process, dividing material preparation into six core steps: carbon aerogel preparation, silica sol formulation, in-situ composite gelation, aging, supercritical drying, and deodorization. The process is seamless and free of redundancy. Compared to the cumbersome processes of existing technologies involving multi-stage high-temperature heat treatment, multi-system silica sol step-by-step preparation, and fiber impregnation composite, the number of steps is reduced by more than 50%, significantly shortening the preparation cycle. Furthermore, the raw material ratios, reaction temperatures, pH values, and drying parameters of this invention are all designed with a wide-adaptability process window. Multiple embodiments have consistently produced high-performance target materials under different parameter ratios, demonstrating high process tolerance and eliminating the need for ultra-high-precision specialized equipment control, making it suitable for continuous industrial production. In addition, the silicon source, carbon source, catalyst, and pore expander used in this invention are all readily available bulk industrial chemicals, without any rare or expensive specialty raw materials. The core drying process utilizes the supercritical CO2 drying technology already matured in the aerogel industry, eliminating the need for additional dedicated production lines and significantly reducing equipment investment and raw material costs for industrial production, demonstrating strong potential for industrialization.

[0029] 5. Existing tobacco filter materials generally have obvious performance shortcomings. Activated carbon adsorbents have high adsorption resistance and easily damage the taste of cigarettes. Pure silica aerogels are prone to powdering and are brittle. Fiber composite aerogels have high adsorption resistance and low adsorption efficiency. Carbon composite aerogels have a narrow adsorption spectrum and complex processes. None of them can simultaneously meet the comprehensive requirements of "safe use, smooth smoking, high harm reduction efficiency, simple processing, and controllable cost" in tobacco use scenarios. This invention deeply integrates and synergistically optimizes five key properties—non-powdering safety, low-resistance vaping experience, broad-spectrum high adsorption for harm reduction, excellent flexible processability, and low-cost industrialization potential—through molecular-level framework modification, precise nanoscale pore control, and in-situ composite innovation at the process level. The material prepared by this invention can be directly made into replaceable capsules for use in cigarette filter mouthpieces without modifying existing mouthpiece structures, exhibiting extremely high adaptability. It not only meets consumers' core health and harm reduction needs but also ensures a good vaping experience while completely eliminating the safety hazards of powder inhalation. It has extremely high application value in civilian cigarette filter mouthpieces, cigarette filter rods, and other scenarios. Attached Figure Description

[0030] Figure 1 This is a flowchart illustrating the preparation process of the silica composite aerogel adsorbent material described in this invention.

[0031] Figure 2 This is a schematic diagram of the structure of a filter cigarette holder made from the silica composite aerogel adsorption material described in this invention.

[0032] In the figure: 1 is a metal nozzle; 2 is a replaceable filter capsule; 3 is a metal outer cylinder; 4 is an aerogel adsorption filter made of silica composite aerogel adsorption material as described in this invention; 5 is a flow-guiding buffer foam; 6 is a smoke receiving base. Detailed Implementation

[0033] The technical solutions of the present invention will be clearly and completely described in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the present invention are within the scope of protection of the present invention.

[0034] Unless otherwise specified in the specific circumstances, the numerical ranges listed herein include upper and lower limits, as well as all integers and fractions within that range, but are not limited to the specific values ​​listed when the range is defined.

[0035] Unless otherwise specified, the experimental methods used in this invention are all conventional methods.

[0036] Unless otherwise specified, all materials and reagents used in this invention can be purchased or synthesized by known methods.

[0037] In the quantitative experiments of this invention, each experiment was repeated three times, and the average value of the results was taken.

[0038] I. A non-powder-shedding flexible silica composite aerogel adsorbent material

[0039] Addressing the core technical problems commonly found in existing cigarette smoke filtration materials, including the safety hazards caused by the brittleness and easy cracking and powder shedding of traditional silica aerogels, the inherent contradiction between adsorption efficiency and smoke absorption resistance in activated carbon and powder-based adsorbent materials, the performance defects of existing carbon-silicon composite aerogel technology such as narrow adsorption spectrum and poor interception effect on core harmful substances in smoke like tar, and the technical difficulties of complicated, costly, and difficult-to-scale industrialization preparation processes for high-performance aerogel materials, this invention systematically constructs a non-powdering flexible silica composite aerogel adsorbent material from four perspectives: control of intrinsic material properties, precise design of pore structure, synergistic optimization of adsorption mechanism, and industrial adaptation of process route. At the level of intrinsic material modification, flexible alkyl groups are grafted onto the rigid silica framework through the design of silicon source molecules composed of alkylsilanes and silicates, thereby improving brittleness and inhibiting powder formation from the root of the material's molecular structure. At the level of pore structure design, a two-stage pore-expanding process of carbon aerogel preparation and silica sol formulation is adopted to construct a hierarchical interconnected pore structure of "large pores for airflow and mesopores / micropores for adsorption," thus solving the core industry contradiction of the inability to simultaneously achieve high adsorption efficiency and low suction resistance from a structural design perspective. At the level of adsorption mechanism optimization, highly porous materials can be controllably prepared through a "sol-gel-gradient calcination-etching" process. A nitrogen-containing carbon aerogel with large porosity is in-situ doped and composited with hydrophobically modified silica aerogel to construct a dual-mechanism adsorption system that synergistically combines physical and chemical adsorption. This achieves simultaneous and efficient retention of all harmful components of cigarette smoke, including non-polar tar, nicotine, and polar aldehydes, carbon monoxide, etc. In terms of process adaptation, a one-step in-situ sol-gel process route is designed, employing a weakly alkali-controlled slow gelation process to achieve uniform anchoring and overall encapsulation of the carbon aerogel within the silica network. Combined with the supercritical CO2 drying process, which is already maturely applied in the aerogel industry, the preparation process is significantly simplified and the process parameter window is broadened. Based on the above design concept, this invention ultimately constructs a non-shedding flexible silica composite aerogel adsorbent material. This composite aerogel adsorbent material is composed of SiO2 aerogel and carbon aerogel materials in situ composite and is used as an adsorbent material for cigarette filter mouthpieces, effectively adsorbing harmful substances in cigarette smoke. The mass ratio of silica aerogel to carbon aerogel is 1:(0.1~0.3).

[0040] The silica composite aerogel adsorbent material of this invention has achieved many unexpected technical effects in practical applications: First, it overcomes the technical problem of the trade-off between various core performance characteristics in existing technologies, achieving synergistic effects across all dimensions of material performance. It simultaneously ensures safety by preventing powder shedding, ultra-low smoke suction resistance of less than 1000 Pa, and a maximum harmful substance retention rate of 88%, solving the long-standing industry problem of being unable to balance safety, suction experience, and harm reduction. Second, the material's adsorption capacity for harmful substances in smoke reaches more than 20 times its own weight, far exceeding the upper limit of adsorption rates for existing similar aerogel materials, and simultaneously adsorbs multiple components such as tar, aldehydes, and carbon monoxide. The broad-spectrum and efficient adsorption of harmful substances in flue gas completely overcomes the performance defects of existing technologies, which have a narrow adsorption spectrum and can only achieve the retention of single harmful substances. Furthermore, while achieving a comprehensive improvement in the overall performance of the material, the preparation process is greatly simplified. The process has a high tolerance for error, the raw materials are all bulk industrial chemicals, and no new special production equipment is required. It has great potential for large-scale application and solves the technical problem of "good performance but difficult mass production" of high-performance aerogel materials. Finally, the prepared monolithic aerogel material has both excellent flexibility and mechanical stability, and can be directly adapted to the existing filter mouthpiece structure without additional modification to the mouthpiece product. It has extremely high application value in the fields of civilian filter mouthpieces and cigarette filter rods.

[0041] In some embodiments of this invention, it has been discovered that high-porosity, macroporous nitrogen-containing carbon aerogels can be prepared by the following method, providing a core carbon phase component with a unique structure and function for composite aerogel systems. Through precise proportioning design of resorcinol-formaldehyde carbon precursor, tetraethyl orthosilicate hard template, and pore-expanding agent, combined with a mild gelation process using a low-dose alkaline catalyst, uniform cross-linking and structural stability of the carbon skeleton are ensured. Then, through stepwise gradient calcination, carbonization, graphitization, and in-situ nitrogen doping are completed in stages, constructing abundant nitrogen-containing active functional groups on the carbon skeleton. This provides specific chemical adsorption sites for polar gaseous pollutants such as aldehydes and carbon monoxide, precisely compensating for the inherent weakness of pure silica aerogels in adsorbing polar pollutants. Finally, the silica hard template is removed by etching with hydrofluoric acid / strong alkali, forming a through-pore structure on the carbon skeleton. This provides a low-resistance flow channel for flue gas, while allowing sufficient contact between the flue gas and the internal adsorption sites, laying a core material foundation for the subsequent dual-mechanism synergistic adsorption and the balance between low adsorption resistance and high adsorption performance in composite aerogels. The carbon aerogel is prepared by the following method: resorcinol, formaldehyde, pore-expanding agent, and tetraethyl orthosilicate are mixed evenly, then an alkaline catalyst is added to induce gelation, followed by aging of the gel with an alcohol solvent, and then drying and calcining to obtain a silica-carbon composite aerogel. The silica-carbon composite aerogel is then etched in a hydrofluoric acid or strong alkaline solution and dried to obtain a high-porosity, macroporous, nitrogen-containing carbon aerogel. The molar ratio of resorcinol, formaldehyde, pore-expanding agent, and tetraethyl orthosilicate is 1:2:(0.05-0.1):(0.1-0.2); the molar ratio of resorcinol to alkaline catalyst is (300-1000). ): 1; The pore-expanding agent is hexadecyltrimethylammonium bromide or hexadecyltrimethylammonium chloride; the alkaline catalyst is one or both of ammonia or tetramethylammonium hydroxide; the solvent is one of methanol, ethanol or propanol; the drying and calcination temperature is gradient drying, and the specific drying parameters are: 300℃ for 0.5h, 600℃ for 0.5h, 800℃ for 1-2h, 1000℃ for 1-2h, and 1200℃ for 1-2h; the etching solution is hydrofluoric acid or one of sodium hydroxide or potassium hydroxide, with a concentration of 3~8mol / L, an etching time of 2~10h, and an etching temperature of 25~50℃.

[0042] In some embodiments of the present invention, the composite aerogel adsorbent material is prepared by the following method:

[0043] Step 1: Mix the silicon source, solvent, catalyst, and pore expander evenly, and stir continuously at 25℃~50℃ for 1h~4h to prepare a sol; wherein, the mass ratio of silicon source, solvent, catalyst, and pore expander is 1:(1.5-2.5):(0.4-0.7):(0.02-0.08).

[0044] Step 2: Add an alkaline catalyst to the sol prepared in Step 1 to adjust the pH to 7-8, then add carbon aerogel powder, pour it into a mold and heat to gel to obtain a wet gel material; wherein, the temperature is heated to 50-70℃.

[0045] Step 3: Place the wet gel material prepared in step 2 into an alcohol solution, and add an alkaline solution to the alcohol solution to adjust the pH value to 8~9. Age it at 55℃~75℃ for 10h~24h.

[0046] Step 4: The aged wet gel from Step 3 is dried with supercritical CO2 to obtain the composite aerogel adsorbent material.

[0047] Step 5: Dry and deodorize the composite aerogel adsorbent material obtained in Step 4.

[0048] This invention achieves in-situ integrated composite of modified silica aerogel and self-made carbon aerogel through a closed-loop process of sol preparation, in-situ composite gel, aging, supercritical drying, and deodorization. It constructs an integral composite aerogel with a flexible framework, hierarchical channels, and dual-mechanism adsorption sites, systematically solving the technical problems of "easy powder shedding, high draw resistance, low adsorption efficiency, and high brittleness" of existing aerogel materials when applied to the cigarette industry. The sol-gel preparation process under controlled temperature ensures the full and uniform hydrolysis of the silicon source, laying the foundation for constructing a continuous and stable three-dimensional silica framework. The in-situ composite gel process under near-neutral pH control uniformly anchors the carbon aerogel powder in the silica cross-linked network, forming an interpenetrating double continuous structure, eliminating the risk of carbon aerogel powder detachment from the source, while ensuring that the adsorption sites of the two materials are fully exposed, achieving synergistic adsorption enhancement. The alkaline heating aging process strengthens the gel framework and repairs microstructural defects, avoiding cracking, shrinkage, and embrittlement problems during subsequent drying. The supercritical CO2 drying process perfectly preserves the high porosity and hierarchical pore structure of the material, which is the core guarantee for achieving low adsorption resistance and high adsorption performance. The end-of-line drying and deodorization process is specifically adapted to the smoking scenario, completely removing residual organic solvents, by-products, and odors from the material, avoiding interference with the smoking taste of cigarettes, and fully realizing the core technical objectives of this invention.

[0049] In some embodiments of the present invention, in step 1, the pore-expanding agent is hexadecyltrimethylammonium bromide or hexadecyltrimethylammonium chloride; the silicon source is a mixture of silane compound and silicate ester compound, wherein the silane compound is one or two of methyltrimethoxysilane, methyltriethoxysilane, trimethylmethoxysilane, dimethyldimethoxysilane, and dimethyldiethoxysilane, and the silicate ester compound is one or two of tetraethyl orthosilicate or methyl orthosilicate, and the molar ratio of silane compound to silicate ester compound is 1:(0.05~0.2); the catalyst is an aqueous solution of one or two of nitric acid, hydrochloric acid, acetic acid, sulfuric acid, or phosphoric acid, with a concentration of 0.2mol / L~1mol / L. Among them, the composite silicon source system of alkylsilane compounds and silicate ester compounds can introduce a large number of flexible alkyl groups on the rigid Si-O-Si framework, solving the technical problems of high brittleness and easy cracking and powdering of pure silicate ester aerogel from the material's intrinsic nature. At the same time, it significantly improves the hydrophobicity and oleophilicity of the material, and significantly enhances the physical adsorption capacity of particulate harmful substances such as oily tar and nicotine in flue gas. The precise ratio range also balances the flexibility and framework strength of the material, avoiding over- or under-modification. The pore expander added at the sol stage can build a rich mesoporous / microporous structure in the silica framework, forming a hierarchical pore system of "large pores for airflow and mesopores / micropores for adsorption" with the macropores of carbon aerogel, further solving the inherent contradiction between high adsorption efficiency and low suction resistance. The 0.2~1 mol / L dilute acid catalyst can precisely control the silicon source hydrolysis rate, realize a mild and controllable hydrolysis process, avoid sol agglomeration and system inhomogeneity, and ensure the formation of a uniform and stable silica sol, providing a core prerequisite for the subsequent construction of a defect-free continuous gel framework.

[0050] In some embodiments of the present invention, in step 2, the alkaline catalyst is one or two of ammonium carbonate, ammonium acetate buffer, or urea.

[0051] In some embodiments of the present invention, in step 3, the alcohol solution is one of methanol, ethanol or propanol; the alkaline solution is one or two of sodium hydroxide, potassium hydroxide or ammonia water.

[0052] In some embodiments of the present invention, in step 4, the supercritical CO2 drying conditions are as follows:

[0053] The CO2 flow rate is 450L / h~600L / h, the drying temperature is 45℃~55℃, the drying pressure is 14.5MPa~16.5MPa, and the drying time is 3h~8h.

[0054] In some embodiments of the present invention, the resistance value of the composite aerogel adsorption material is less than 1000 Pa, and the adsorption mass is at least 20 times the mass of the material itself.

[0055] II. A type of filter cigarette holder

[0056] The filter mouthpiece contains the aforementioned non-shedding flexible silica composite aerogel adsorbent material, including but not limited to its use with a metal sleeve to form a filter mouthpiece. For example... Figure 2 As shown, 1 is a metal mouthpiece with a suction end for the user to inhale and guide air; 2 is a replaceable filter capsule, used to carry and encapsulate the filter material, serving as the carrier of the filter core; 3 is a metal outer cylinder, the main supporting structure of the mouthpiece, undertaking the core functions of connecting both ends, positioning the internal filter core, and sealing the air passage; 4 is an aerogel adsorption filter, the composite aerogel adsorption material described in this invention, playing a core filtering role; 5 is a flow-guiding buffer foam, pre-filtering large particles of tar and soot in the smoke; uniformly distributing airflow, allowing the smoke to pass evenly through the filter core material, avoiding local high-speed scouring and damage to the filter core material; buffering and limiting, preventing the filter core material from shifting; sealing gaps, preventing smoke from flowing around; 6 is a cigarette receiving base, connecting the cigarette body and guiding the smoke. The metal mouthpiece, replaceable filter capsule, metal outer cylinder, flow-guiding buffer foam, aerogel adsorption filter, and cigarette receiving base are assembled according to the commonly used cigarette filter mouthpiece structure in the prior art to obtain the filter mouthpiece.

[0057] III. Examples and Comparative Examples

[0058] The preparation process of the following embodiments is as follows: Figure 1 As shown.

[0059] Example 1

[0060] Step 1: Preparation of carbon aerogel powder: Resorcinol, formaldehyde, hexadecyltrimethylammonium bromide, and tetraethyl orthosilicate were added to a beaker in a molar ratio of 1:2:0.05:0.15 and stirred. Then, tetramethylammonium hydroxide base catalyst with a molar ratio of 750:1 to resorcinol was added to gel the aerogel. The gel was aged by adding ethanol solvent, and then subjected to supercritical drying. The aerogel was then subjected to gradient drying in a muffle furnace at 300℃ for 0.5h, 600℃ for 0.5h, 800℃ for 1h, 1000℃ for 1.5h, and 1200℃ for 1h to obtain silica-carbon composite aerogel. The composite aerogel was etched in a 5mol / L hydrofluoric acid solution at 30℃ for 4h. After drying at 60℃, a high-porosity macroporous nitrogen-containing carbon aerogel was obtained.

[0061] Step 2: Preparation of sol: Tetraethyl orthosilicate in a molar ratio of 0.1:1 was mixed with a mixture of methyltriethoxysilane and dimethyldiethoxysilane in a molar ratio of 1:0.4. Ethanol in a mass ratio of 1:1.8:0.55:0.04, 0.5 mol / L dilute nitric acid aqueous solution, and hexadecyltrimethylammonium bromide pore expander were added and mixed evenly. The mixture was stirred continuously at 45°C for 2 hours to prepare a sol.

[0062] Step 3: Preparation of silica composite aerogel adsorbent material: Add urea solution to the sol prepared in step 2 to adjust the pH to about 7.2, stir evenly, and place in a 60℃ hot water bath to gel. When the sol turns slightly white, add high porosity macroporous nitrogen-containing carbon aerogel and stir evenly. Pour into a mold of a specific size and heat to gel to obtain a wet gel material. The theoretical mass ratio of carbon aerogel added to silica aerogel is 0.25:1.

[0063] Step 4: Aging the gel: The wet gel material prepared in step 3 is immersed in an alkaline ethanol solution for aging. The alkalinity of the ethanol is adjusted to pH 8.5 by an ammonia aqueous solution. The aging temperature is 70℃ and the aging time is 16h, during which the immersion solution is changed every 8h.

[0064] Step 5: Drying the gel: The wet gel material aged in Step 4 is dried by supercritical CO2 to obtain a non-powdering flexible silica composite aerogel adsorbent material. The drying process conditions are: CO2 flow rate 500 L / h, drying temperature 55℃, drying pressure 15 MPa, and drying time 4 h.

[0065] Step 6: Drying and deodorizing: Place the non-powder-shedding flexible silica composite aerogel adsorbent material from Step 5 into a forced-air drying oven for drying and deodorizing at a temperature of 130℃ for 5 hours.

[0066] Step 7: Preparation of the filter mouthpiece: The non-shedding flexible silica composite aerogel adsorbent material obtained in Step 6 is placed into a capsule of a specific size. The capsule has openings at both ends for ventilation. The capsule is then placed in a metal sleeve and connected to a metal mouthpiece to form the filter mouthpiece. The non-shedding flexible silica composite aerogel adsorbent material can fully rebound to 99.3% after 30% compression. This mouthpiece, tested according to GB / T 22838.5-2024, has a resistance value of 800 Pa and a 92% rejection rate for tar and other harmful substances.

[0067] Example 2

[0068] Step 1: Preparation of carbon aerogel powder: Resorcinol, formaldehyde, hexadecyltrimethylammonium bromide, and tetraethyl orthosilicate were added to a beaker in a molar ratio of 1:2:0.1:0.1 and stirred. Then, ammonia-based alkaline catalyst with a molar ratio of 500:1 to resorcinol was added to gel the aerogel. The gel was aged by adding methanol solvent and then subjected to supercritical drying. The aerogel was then subjected to gradient drying in a muffle furnace at 300℃ for 0.5h, 600℃ for 0.5h, 800℃ for 2h, 1000℃ for 1h, and 1200℃ for 1h to obtain silica-carbon composite aerogel. The composite aerogel was etched in an 8mol / L hydrofluoric acid solution at 25℃ for 2h. After drying at 60℃, a high-porosity macroporous carbon aerogel was obtained.

[0069] Step 2: Preparation of sol: Methyl orthosilicate with a molar ratio of 0.05:1 was mixed with a mixture of methyltrimethoxysilane and dimethyldimethoxysilane with a molar ratio of 1:0.2. Methanol with a mass ratio of 1:1.5:0.4:0.02, 0.2 mol / L dilute hydrochloric acid aqueous solution, and hexadecyltrimethylammonium chloride pore expander were added and mixed evenly. The mixture was stirred continuously at 50°C for 1 hour to prepare a sol.

[0070] Step 3: Preparation of silica composite aerogel adsorbent material: Add ammonium carbonate solution to the sol prepared in step 2 to adjust the pH to about 7.5, stir evenly, and place in a 50℃ hot water bath to gel. When the sol turns slightly white, add high porosity macroporous nitrogen-containing carbon aerogel and stir evenly. Pour into a mold of a specific size and heat to gel to obtain wet gel material. The theoretical mass ratio of carbon aerogel added to silica aerogel is 0.15:1. The soaking solution is changed every 8 hours.

[0071] Step 4: Aging the gel: The wet gel material prepared in step 3 is immersed in an alkaline methanol solution for aging. The alkalinity of the methanol is adjusted to pH 9 by sodium hydroxide aqueous solution. The aging temperature is 55℃ and the aging time is 12h.

[0072] Step 5: Drying the gel: The wet gel material aged in Step 4 is dried with supercritical CO2 to obtain a non-powdering flexible silica composite aerogel adsorbent material. The drying process conditions are: CO2 flow rate 600 L / h, drying temperature 45℃, drying pressure 13.5 MPa, and drying time 3h.

[0073] Step 6: Drying and deodorizing: Place the non-powder-shedding flexible silica composite aerogel adsorbent material from Step 5 into a forced-air drying oven for drying and deodorizing at a temperature of 110℃ for 7 hours.

[0074] Step 7: Preparation of the filter mouthpiece: The non-shedding flexible silica composite aerogel adsorbent material obtained in Step 6 is placed into a capsule of a specific size. The capsule has openings at both ends for ventilation. The capsule is then placed in a metal sleeve and connected to a metal mouthpiece to form the filter mouthpiece. The non-shedding flexible silica composite aerogel adsorbent material can fully rebound to 98.7% after 30% compression. This mouthpiece, tested according to GB / T 22838.5-2024, has a resistance value of 900 Pa and a retention rate of 85% for tar and other harmful substances.

[0075] Example 3

[0076] Step 1: Preparation of carbon aerogel powder: Resorcinol, formaldehyde, hexadecyltrimethylammonium chloride, and tetraethyl orthosilicate were added to a beaker in a molar ratio of 1:2:0.05:0.2 and stirred. Then, tetramethylammonium hydroxide base catalyst with a molar ratio of 1000:1 to resorcinol was added to gel the aerogel. The gel was aged by adding ethanol solvent and then subjected to supercritical drying. The aerogel was then subjected to gradient drying in a muffle furnace at 300℃ for 0.5h, 600℃ for 0.5h, 800℃ for 1h, 1000℃ for 2h, and 1200℃ for 1h to obtain silica-carbon composite aerogel. The composite aerogel was etched in an 8mol / L sodium hydroxide solution at 40℃ for 6h. After drying at 60℃, a high-porosity macroporous carbon aerogel was obtained.

[0077] Step 2: Preparation of sol: Tetraethyl orthosilicate in a molar ratio of 0.2:1 was mixed with a mixture of methyltriethoxysilane and dimethyldiethoxysilane in a molar ratio of 1:0.6. Ethanol in a mass ratio of 1:2.5:0.7:0.08, 0.8 mol / L dilute sulfuric acid aqueous solution, and hexadecyltrimethylammonium bromide pore expander were added and mixed evenly. The mixture was stirred continuously at 30°C for 3 hours to prepare a sol.

[0078] Step 3: Preparation of silica composite aerogel adsorbent material: Add ammonium acetate buffer solution to the sol prepared in step 2 to adjust the pH to greater than 7, stir evenly, and place in a 60℃ hot water bath to gel. When the sol turns slightly white, add nitrogen-containing carbon aerogel with high porosity and macroporous structure and stir evenly. Pour into a mold of a specific size and heat to gel to obtain wet gel material. The theoretical mass ratio of carbon aerogel added to silica aerogel is 0.1:1.

[0079] Step 4: Aging the gel: The wet gel material prepared in step 3 is immersed in an alkaline ethanol solution for aging. The alkalinity of the ethanol is adjusted to pH 9 by sodium hydroxide aqueous solution. The aging temperature is 75℃ and the aging time is 10h, during which the immersion solution is changed every 8h.

[0080] Step 5: Drying the gel: The wet gel material aged in Step 4 is dried by supercritical CO2 to obtain a non-powdering flexible silica composite aerogel adsorbent material. The drying process conditions are: CO2 flow rate 450 L / h, drying temperature 50℃, drying pressure 16 MPa, and drying time 8 h.

[0081] Step 6: Drying and deodorizing: Place the non-powder-shedding flexible silica composite aerogel adsorbent material from Step 5 into a forced-air drying oven for drying and deodorizing at a temperature of 150℃ for 3 hours.

[0082] Step 7: Preparation of the filter mouthpiece: The non-shedding flexible silica composite aerogel adsorbent material obtained in Step 6 is placed into a capsule of a specific size. The capsule has openings at both ends for ventilation. The capsule is then placed in a metal sleeve and connected to a metal mouthpiece to form the filter mouthpiece. The non-shedding flexible silica composite aerogel adsorbent material can fully rebound to 97.6% after 30% compression. This mouthpiece, tested according to GB / T 22838.5-2024, has a resistance value of 700 Pa and a retention rate of 83% for tar and other harmful substances.

[0083] Example 4

[0084] Step 1: Preparation of carbon aerogel powder: Resorcinol, formaldehyde, hexadecyltrimethylammonium bromide, and tetraethyl orthosilicate were added to a beaker in a molar ratio of 1:2:0.1:0.2 and stirred. Then, tetramethylammonium hydroxide base catalyst with a molar ratio of 300:1 to resorcinol was added to gel the aerogel. The gel was aged by adding ethanol solvent and then subjected to supercritical drying. The aerogel was then subjected to gradient drying in a muffle furnace at 300℃ for 0.5h, 600℃ for 0.5h, 800℃ for 1h, 1000℃ for 1h, and 1200℃ for 2h to obtain silica-carbon composite aerogel. The composite aerogel was etched in a 3mol / L hydrofluoric acid solution at 35℃ for 8h. After drying at 60℃, a high-porosity macroporous carbon aerogel was obtained.

[0085] Step 2: Preparation of sol: Methyl orthosilicate with a molar ratio of 0.1:1 was mixed with a mixture of trimethylmethoxysilane and dimethyldimethoxysilane with a molar ratio of 1:0.2. Methanol with a mass ratio of 1:2.2:0.4:0.06, 1 mol / L dilute acetic acid aqueous solution, and hexadecyltrimethylammonium chloride pore expander were added and mixed evenly. The mixture was stirred continuously at 25°C for 4 hours to prepare a sol.

[0086] Step 3: Preparation of silica composite aerogel adsorbent material: Add urea solution to the sol prepared in step 2 to adjust the pH to about 7.1, stir evenly, and place in a 50℃ hot water bath to gel. When the sol turns slightly white, add high porosity macroporous nitrogen-containing carbon aerogel and stir evenly. Pour into a mold of a specific size and heat to gel to obtain wet gel material. The theoretical mass ratio of carbon aerogel added to silica aerogel is 0.2:1.

[0087] Step 4: Aging the gel: The wet gel material prepared in step 3 is immersed in an alkaline methanol solution for aging. The alkalinity of the methanol is adjusted to pH 8 by potassium hydroxide aqueous solution. The aging temperature is 60℃ and the aging time is 24h, during which the immersion solution is changed every 8h.

[0088] Step 5: Drying the gel: The wet gel material aged in Step 4 is dried with supercritical CO2 to obtain a non-powdering flexible silica composite aerogel adsorbent material. The drying process conditions are: CO2 flow rate 550 L / h, drying temperature 55℃, drying pressure 17.5 MPa, and drying time 5 h.

[0089] Step 6: Drying and deodorizing: Place the non-powder-shedding flexible silica composite aerogel adsorbent material from Step 5 into a forced-air drying oven for drying and deodorizing at a temperature of 100℃ for 8 hours.

[0090] Step 7: Preparation of the filter mouthpiece: The non-shedding flexible silica composite aerogel adsorbent material obtained in Step 6 is placed into a capsule of a specific size. The capsule has openings at both ends for ventilation. The capsule is then placed in a metal sleeve and connected to a metal mouthpiece to form the filter mouthpiece. The non-shedding flexible silica composite aerogel adsorbent material can fully rebound to 98.3% after 30% compression. This mouthpiece, tested according to GB / T 22838.5-2024, has a resistance value of 830 Pa and a retention rate of 85% for tar and other harmful substances.

[0091] Example 5

[0092] Step 1: Preparation of carbon aerogel powder: Resorcinol, formaldehyde, hexadecyltrimethylammonium bromide, and tetraethyl orthosilicate were added to a beaker in a molar ratio of 1:2:0.1:0.15 and stirred. Then, tetramethylammonium hydroxide base catalyst with a molar ratio of 500:1 to resorcinol was added to gel the aerogel. The gel was aged by adding ethanol solvent and then subjected to supercritical drying. The aerogel was then subjected to gradient drying in a muffle furnace at 300℃ for 0.5 h, 600℃ for 0.5 h, 800℃ for 1 h, 1000℃ for 2 h, and 1200℃ for 1 h to obtain silica-carbon composite aerogel. The composite aerogel was etched in a 3 mol / L sodium hydroxide solution at 50℃ for 10 h. After drying at 60℃, a high-porosity macroporous carbon aerogel was obtained.

[0093] Step 2: Preparation of sol: Tetraethyl orthosilicate and methyltriethoxysilane were mixed in a molar ratio of 0.1:1, and propanol, 0.6 mol / L dilute nitric acid aqueous solution and hexadecyltrimethylammonium bromide pore expander were added at the same time and mixed evenly. The mixture was stirred continuously at 35°C for 2 hours to prepare a sol.

[0094] Step 3: Preparation of silica composite aerogel adsorbent material: Add ammonium carbonate solution to the sol prepared in step (1) to adjust the pH to about 8, stir evenly and place in a 70°C hot water bath to gel. When the sol turns slightly white, add nitrogen-containing carbon aerogel with high porosity and macroporous structure and stir evenly. Pour into a mold of a specific size and heat to gel to obtain wet gel material. The ratio of the amount of carbon aerogel added to the theoretical mass of silica aerogel is 0.3:1.

[0095] Step 4: Aging the gel: The wet gel material prepared in step 3 is immersed in an alkaline propanol solution for aging. The alkalinity of the propanol is adjusted to pH 8.5 by an ammonia solution. The aging temperature is 75°C and the aging time is 16 hours, during which the immersion solution is changed every 8 hours.

[0096] Step 5: Drying the gel: The wet gel material aged in Step 4 is dried by supercritical CO2 to obtain a non-powdering flexible silica composite aerogel adsorbent material. The drying process conditions are: CO2 flow rate 550 L / h, drying temperature 55℃, drying pressure 15 MPa, and drying time 5 h.

[0097] Step 6: Drying and deodorizing: Place the non-powder-shedding flexible silica composite aerogel adsorbent material from Step 5 into a forced-air drying oven for drying and deodorizing at a temperature of 120℃ for 6 hours.

[0098] Step 7: Preparation of the filter mouthpiece: The non-shedding flexible silica composite aerogel adsorbent material obtained in Step 6 is placed into a capsule of a specific size. The capsule has open structures at both ends to facilitate air permeability. The capsule is then placed in a metal sleeve and connected to a metal mouthpiece to form the filter mouthpiece. The non-shedding flexible silica composite aerogel adsorbent material can fully rebound to 97% after 30% compression. This mouthpiece, tested according to GB / T 22838.5-2024, has a resistance value of 950 Pa and a retention rate of 81% for tar and other harmful substances.

[0099] Comparative Example 1

[0100] The method was modified from Example 1, with the difference that silane compounds were not added in step 2 during the sol preparation stage. Specifically, tetraethyl orthosilicate, ethanol, dilute nitric acid, and hexadecyltrimethylammonium bromide pore expander were mixed uniformly in a mass ratio of 1:1.8:0.55:0.04, with the concentration of dilute nitric acid being 0.5 mol / L. Other steps were identical to Example 1. The silica composite aerogel adsorbent material prepared in this comparative example was used to make a filter cigarette holder. The non-shedding flexible silica composite aerogel adsorbent material could not recover after 30% compression. The cigarette holder tested according to GB / T 22838.5-2024 showed a resistance value of 3440 Pa and a retention rate of 53% for tar and other harmful substances. This silica composite aerogel adsorbent material is brittle and prone to shedding powder, and has relatively high inhalation and exhalation resistance.

[0101] Comparative Example 2

[0102] Based on Example 1, the following adjustments were made: In step 2, no pore-expanding agent was added during the sol preparation stage. Specifically, tetraethyl orthosilicate, methyltriethoxysilane, and dimethyldiethoxysilane were mixed uniformly in a molar ratio of 0.1:1:0.4. Then, ethanol and dilute nitric acid were added to the mixture, with a mass ratio of 1:1.8:0.55 for the mixture and a concentration of 0.5 mol / L for the dilute nitric acid. The other steps were identical to those in Example 1. The silica composite aerogel adsorbent material prepared in this comparative example was used to make a filter cigarette holder. The non-shedding flexible silica composite aerogel adsorbent material could fully rebound to 94% after 30% compression. The cigarette holder tested according to GB / T 22838.5-2024 showed a resistance value of 4310 Pa and a retention rate of 63% for harmful substances such as tar. The absence of a pore-expanding agent during the sol preparation stage resulted in smaller pore size, decreased porosity, increased inhalation and exhalation assistance, but also a lower adsorption rate for harmful substances.

[0103] Comparative Example 3

[0104] The method was modified from Example 1, except that carbon aerogel was not added in step 3. All other steps were identical to Example 1. The silica composite aerogel adsorbent material prepared in this comparative example was used to make a filter cigarette holder. The non-shedding flexible silica composite aerogel adsorbent material could fully rebound to 96% after 30% compression. The cigarette holder tested according to GB / T 22838.5-2024 had a resistance value of 1860 Pa and a retention rate of 52% for tar and other harmful substances. The adsorbent material prepared in this comparative example showed a significant reduction in the adsorption rate of tar and other harmful substances.

[0105] Comparative Example 4

[0106] Based on Example 1, adjustments were made, the difference being that a strong alkali was used to accelerate gelation in step 3. Specifically, sodium hydroxide solution was added to the sol prepared in step 3 to adjust the pH to approximately 9, and after stirring evenly, it was placed in a 60°C hot water bath to allow gelation. Other steps were identical to Example 1. The silica composite aerogel adsorbent material prepared in this comparative example was used to make a filter cigarette holder. The non-shedding, flexible silica composite aerogel adsorbent material could rebound to 83% after 30% compression. The cigarette holder tested according to GB / T 22838.5-2024 showed a resistance value of 3560 Pa and a retention rate of 68% for tar and other harmful substances. The adsorbent material prepared in this comparative example was prone to surface powder shedding, had higher inhalation and exhalation resistance, and exhibited a lower adsorption rate for harmful substances.

[0107] As can be seen from the examples and comparative examples:

[0108] (1) All embodiments of the present invention use a silicon source system composed of alkylsilane and silicate ester, introducing flexible alkyl groups on the rigid Si-O-Si framework. The materials prepared in the end are free from brittle cracking and powder shedding, and achieve excellent performance with a stable mouthpiece resistance value below 1000 Pa and a tar and other harmful substance retention rate of more than 81%. In stark contrast, Comparative Example 1 uses only tetraethyl orthosilicate as a single silicon source, completely removing alkylsilane compounds. The materials prepared in the end exhibit serious problems of brittleness and powder shedding. The mouthpiece resistance value soars to 3440 Pa, far exceeding the acceptable range for cigarette smoking, and the tar retention rate is only 53%, less than 60% of the optimal embodiment. This indicates that the introduction of alkylsilanes not only endows the material with intrinsic flexibility through skeletal modification, fundamentally suppressing powder generation and solving the core safety hazard of aerogel materials in tobacco use scenarios; at the same time, it can also effectively regulate the pore structure and surface hydrophobicity and oleophilicity of the material, significantly reducing the resistance to smoke extraction while significantly enhancing the adsorption capacity for harmful substances such as oily tar.

[0109] (2) In all embodiments of the present invention, a pore-expanding agent is introduced simultaneously in the two stages of carbon aerogel preparation and silica sol preparation, constructing a hierarchical pore structure of "large pores for airflow and mesopores / micropores for adsorption". Ultimately, while achieving a high harmful substance rejection rate of 81%~92%, the resistance value of the mouthpiece is stably controlled in the low resistance range of 700~950Pa, perfectly balancing adsorption performance and flow performance. In contrast, Comparative Example 2 completely removed the pore-expanding agent in the sol preparation stage, keeping only other process conditions unchanged. This resulted in a reduction in material pore size and a significant decrease in porosity. Not only did the tar rejection rate drop to 63%, but the mouthpiece resistance value also soared to 4310Pa, which could not meet the normal smoking requirements at all. This confirms that the hierarchical pore design of the present invention has indeed achieved unexpected technical effects. The large pores of the carbon aerogel provide a low-resistance through-flow channel for the flue gas, and the mesopores / micropores of the silica aerogel provide sufficient adsorption sites for harmful substances. From the structural design, it completely breaks through the technical problem of "the higher the adsorption efficiency, the greater the suction resistance" of traditional filter materials, and achieves a balance between high harmful substance retention rate and smooth suction experience.

[0110] (3) All embodiments of the present invention use an in-situ doping process to uniformly anchor self-made high-porosity macroporous nitrogen-containing carbon aerogel in a three-dimensional silica network. The hydrophobic and oleophilic properties of silica aerogel are used to achieve physical adsorption of non-polar harmful substances such as tar, and the nitrogen-containing functional groups on the surface of carbon aerogel are used to achieve chemical adsorption of polar harmful substances such as aldehydes and carbon monoxide. The final tar and other harmful substance rejection rate is stable at over 81%, with the optimal rejection rate of Example 1 reaching 92%. In contrast, Comparative Example 3 completely removed the carbon aerogel component, retaining only the modified silica aerogel system. The final cigarette holder resistance value was 1860 Pa, which increased the resistance compared to the examples, and the tar rejection rate dropped sharply to 52%, only 56% of that of Example 1. It is evident that the introduction of carbon aerogel and silica aerogel formed a significant synergistic adsorption effect, which greatly broadened the adsorption spectrum of all components of harmful substances in flue gas, and achieved simultaneous retention of particulate and gaseous harmful substances, improving the retention efficiency of harmful substances by more than 40%, thus completely making up for the deficiency of pure silica aerogel in adsorbing polar harmful substances. At the same time, the removal of the large-pore carbon aerogel caused the pore size of pure silica aerogel to be far smaller than that of Example 1 under the action of the pore-expanding agent, resulting in the resistance value of the mouthpiece increasing to 1860 Pa.

[0111] (4) All embodiments of the present invention use weak base catalysts such as urea, ammonium carbonate, and ammonium acetate buffer to achieve slow gelation under near-neutral pH conditions, enabling uniform growth and cross-linking of silica particles, ultimately forming a defect-free continuous three-dimensional network structure. The material has no risk of dust shedding, and exhibits excellent adsorption resistance and adsorption performance. In contrast, Comparative Example 4 uses a strong base of sodium hydroxide to quickly adjust the pH to 9 to achieve rapid gelation. Other process conditions are completely consistent with Example 1. The surface of the final material is extremely prone to dust shedding, and the cigarette holder resistance value rises to 3560 Pa, with a tar retention rate of only 68%, far lower than the level of the examples. It can be seen that the weak base slow gelation process used in the present invention not only avoids the problems of uneven skeleton growth and local loose cracking caused by rapid gelation of strong bases, but also further eliminates the risk of dust shedding from the process level, and ensures the uniformity and continuity of the material channels, achieving a stable output of low adsorption resistance and high adsorption performance. It is an indispensable key process guarantee for the material's comprehensive performance to meet the standards.

[0112] (5) Examples 1-5 involved wide-range gradient adjustments to the core process parameters, including adjusting the mass ratio of carbon aerogel to silica aerogel between 0.1:1 and 0.3:1, replacing the types of silicon source, pore expander, and catalyst, varying the sol preparation temperature between 25 and 50°C, adjusting the gel hot water bath temperature between 50 and 70°C, varying the supercritical drying time between 3 and 8 hours, and setting multiple gradients for drying and deodorizing temperature and time. All examples consistently achieved the core performance indicators of a mouthpiece resistance value <1000Pa and a tar and other harmful substance retention rate >80%, with no instances of a precipitous drop in performance. This indicates that the technical solution of this invention does not only achieve excellent performance within a specific narrow parameter range, but possesses an extremely wide process adaptability window, low parameter control difficulty, and can well adapt to fluctuations in conditions during continuous industrial production. It solves the common technical problems of "rigorous processes, poor mass production stability, and high scale-up difficulty" in high-performance aerogel materials, and has strong potential for industrial application.

[0113] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit the technical solutions. Those skilled in the art should understand that any modifications or equivalent substitutions to the technical solutions of the present invention without departing from the spirit and scope of the present invention should be covered within the scope of the claims of the present invention.

Claims

1. A non-shedding flexible silica composite aerogel adsorbent material, characterized in that, The composite aerogel adsorbent material is composed of SiO2 aerogel and carbon aerogel in situ, and is used as a filter adsorbent material for cigarette holders. It can effectively adsorb harmful substances in cigarette smoke. The mass ratio of silica aerogel to carbon aerogel is 1:(0.1~0.3).

2. The composite aerogel adsorbent material according to claim 1, characterized in that, The carbon aerogel was prepared by the following method: Resorcinol, formaldehyde, pore-expanding agent and tetraethyl orthosilicate are mixed evenly, then an alkaline catalyst is added to make it gel, then an alcohol solvent is added to age the gel, and then it is dried and calcined to obtain silica-carbon composite aerogel. The silica-carbon composite aerogel is placed in hydrofluoric acid or strong alkaline solution for etching, and after drying, a high porosity macroporous structure nitrogen-containing carbon aerogel is obtained. The molar ratio of resorcinol, formaldehyde, pore expander, and tetraethyl orthosilicate is 1:2:(0.05-0.1):(0.1-0.2); the molar ratio of resorcinol to alkaline catalyst is (300-1000):1; the pore expander is hexadecyltrimethylammonium bromide or hexadecyltrimethylammonium chloride; the alkaline catalyst is one or both of ammonia or tetramethylammonium hydroxide; the solvent is one of methanol, ethanol, or propanol; the drying and calcination temperature is gradient drying, with specific drying parameters as follows: 300℃ for 0.5h, 600℃ for 0.5h, 800℃ for 1-2h, 1000℃ for 1-2h, and 1200℃ for 1-2h; the etching solution is hydrofluoric acid or one of sodium hydroxide or potassium hydroxide, with a concentration of 3-8 mol / L, an etching time of 2-10h, and an etching temperature of 25-50℃.

3. The composite aerogel adsorbent material according to claim 1, characterized in that, The composite aerogel adsorbent material is prepared by the following method: Step 1: Mix the silicon source, solvent, catalyst, and pore expander evenly, and stir continuously at 25℃~50℃ for 1h~4h to prepare a sol; wherein, the mass ratio of silicon source, solvent, catalyst, and pore expander is 1:(1.5-2.5):(0.4-0.7):(0.02-0.08). Step 2: Add an alkaline catalyst to the sol prepared in Step 1 to adjust the pH to 7-8, then add carbon aerogel powder, pour it into a mold and heat to gel to obtain a wet gel material; wherein, the temperature is heated to 40-55℃. Step 3: Place the wet gel material prepared in step 2 into an alcohol solution, and add an alkaline solution to the alcohol solution to adjust the pH value to 8~9. Age it at 55℃~75℃ for 10h~24h. Step 4: The aged wet gel from Step 3 is dried with supercritical CO2 to obtain the composite aerogel adsorbent material. Step 5: Dry and deodorize the composite aerogel adsorbent material obtained in Step 4.

4. The composite aerogel adsorbent material according to claim 3, characterized in that, In step 1, the pore-expanding agent is hexadecyltrimethylammonium bromide or hexadecyltrimethylammonium chloride; the silicon source is a mixture of silane compounds and silicate compounds, wherein the silane compound is one or two of methyltrimethoxysilane, methyltriethoxysilane, trimethylmethoxysilane, dimethyldimethoxysilane, and dimethyldiethoxysilane, and the silicate compound is one or two of tetraethyl orthosilicate or methyl orthosilicate, and the molar ratio of the silane compound to the silicate compound is 1:(0.05~0.2); the catalyst is an aqueous solution of one or two of nitric acid, hydrochloric acid, acetic acid, sulfuric acid, or phosphoric acid, with a concentration of 0.2mol / L~1mol / L.

5. The composite aerogel adsorbent material according to claim 3, characterized in that, In step 2, the alkaline catalyst is one or two of ammonium carbonate, ammonium acetate buffer, or urea.

6. The composite aerogel adsorbent material according to claim 3, characterized in that, In step 3, the alcohol solution is one of methanol, ethanol, or propanol; the alkaline solution is one or two of sodium hydroxide, potassium hydroxide, or ammonia water.

7. The composite aerogel adsorbent material according to claim 3, characterized in that, In step 4, the supercritical CO2 drying conditions are as follows: The CO2 flow rate is 450L / h~600L / h, the drying temperature is 45℃~55℃, the drying pressure is 14.5MPa~16.5MPa, and the drying time is 3h~8h.

8. The composite aerogel adsorbent material according to any one of claims 1 to 7, characterized in that, The resistance value of the composite aerogel adsorption material is less than 1000 Pa, and the adsorption mass is at least 20 times the mass of the material itself.

9. A filter cigarette holder, characterized in that, The filter mouthpiece contains the non-shedding flexible silica composite aerogel adsorbent material as described in any one of claims 1 to 8.

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