Aerogel composite material for dehumidification and preparation method, recovery method and application thereof

Abstract

This invention relates to the field of dehumidification and drying technology, and discloses an aerogel composite material for dehumidification, its preparation method, recycling method, and application. The aerogel composite material includes a polymer aerogel and a moisture-absorbing material distributed on the polymer aerogel; the moisture-absorbing material is a water-soluble moisture-absorbing material; the polymer aerogel contains structural units with maleic anhydride groups and maleimide groups; based on a total weight of 100 wt% for the polymer aerogel and the moisture-absorbing material, the content of the moisture-absorbing material in the aerogel composite material is not less than 10 wt%; wherein the structure of the maleic anhydride groups is [missing information] and the structure of the maleimide groups is [missing information]. This aerogel composite material has a rapid moisture absorption effect, and its moisture absorption ratio is much higher than that of existing materials. After use, the aerogel composite material can be regenerated at a lower temperature, or it can be recycled and reprocessed for reuse, conforming to the concept of circular economy development.

Description

Technical Field

[0001] This invention relates to the field of dehumidification and drying technology, specifically to an aerogel composite material for dehumidification, its preparation method, recycling method, and application. Background Technology

[0002] Humidity is a physical quantity that indicates the degree of dryness or wetness of a gas, specifically the amount of water vapor it contains. At a given temperature, the less water vapor in a given volume of gas, the drier the gas; the more water vapor, the more humid. The degree of dryness or wetness of a gas is called "humidity." Current dehumidification methods include condensation dehumidification, solution dehumidification, solid-state dehumidification, membrane dehumidification, and electrochemical dehumidification. Condensation dehumidification is the most common method, but it requires a large amount of energy for cooling and presents environmental hygiene issues. Solution dehumidification and electrochemical dehumidification also suffer from high energy consumption and high equipment costs. Solid-state dehumidification utilizes the surface adsorption of porous solid materials to absorb moisture from the air, thus achieving dehumidification. The process is simple and is currently a rapidly developing, highly efficient, and energy-saving dehumidification method.

[0003] In industries such as chemical and medical, there are strict requirements regarding the water content in gases. Solid desiccant materials, such as silica gel and molecular sieves, are typically used to treat these gases and reduce their water content. Solid desiccant materials are crucial in solid desiccant treatment; they must first possess a porous structure and be regenerable under certain temperature conditions. Currently common desiccant materials include composite desiccant materials, inorganic desiccant materials, and polymer desiccant materials. For example, Sukhyy et al. used silica gel as a matrix and combined it with sodium sulfate to obtain a composite desiccant with a water absorption capacity of 0.85 g / g (published in Applied Thermal Engineering, Vol. 64, No. 1, 2014, pp. 408-412). Sapienza et al. used vermiculite / lithium nitrate composite materials and achieved a cyclic adsorption capacity of approximately 0.4 g / g (published in Applied Thermal Engineering, Vol. 32, pp. 141-146, 2012). Currently, lithium chloride, silica gel, and metal ion-doped silica gel are common solid dehumidifiers, but they each have drawbacks such as easy leakage and corrosion of equipment, low dehumidification capacity, and poor thermal stability. Many composite dehumidifiers exist, but they all face several problems. First, the moisture absorption capacity needs further improvement. More importantly, most of the matrix materials providing the porous structure cannot be recycled. After multiple cycles, changes in the pore structure render the material unusable, resulting in significant waste. Existing solid dehumidifiers such as molecular sieves and silica gel have low moisture absorption performance and low efficiency, and require regeneration after a short period of use. The regeneration temperature is high, requiring a long purging time at 180°C, resulting in significant energy waste.

[0004] Therefore, it is necessary to develop a moisture-absorbing material with high moisture absorption capacity and recyclability to ensure the development of solid dehumidification. Summary of the Invention

[0005] To address the problems existing in current moisture-absorbing materials, this invention provides an aerogel composite material with an ultra-high moisture absorption ratio. This aerogel composite material has a rapid moisture absorption effect and a moisture absorption ratio far higher than that of existing materials. After use, this aerogel composite material can be regenerated at a low temperature, or it can be recycled and reprocessed for reuse, which is in line with the concept of circular economy development.

[0006] Because water-soluble hygroscopic materials tend to agglomerate after absorbing moisture, they cannot be used directly. A framework material (support) is needed to uniformly disperse the hygroscopic material, resulting in a composite material that prevents agglomeration during preparation or use. Based on hydrophilicity, framework materials are divided into two categories: hydrophilic and non-hydrophilic. Conventionally, if a mixture is used to prepare a hygroscopic composite material, a hydrophilic framework material is required. This is because, on the one hand, a hydrophilic framework material can improve the hygroscopic capacity of the composite material; on the other hand, a poorly hydrophilic framework material may mask some of the hygroscopic material during preparation, reducing the overall hygroscopic performance. However, even with a hydrophilic framework, blending cannot effectively disperse the hygroscopic material and solve the problem of agglomeration, so blending is generally not recommended. For most framework materials (including both hydrophilic and non-hydrophilic ones), impregnation is generally used, where the hygroscopic material is impregnated and then adhered to the framework material.

[0007] Through preliminary research, the research team of this invention obtained a hydrophobic polymer aerogel. According to conventional understanding, if this polymer aerogel is used as the skeleton material of the composite moisture-absorbing material, the hydrophobic polymer aerogel needs to be impregnated and then the moisture-absorbing material is attached to the skeleton material. However, the inventors of this invention found through research that the impregnation method cannot obtain a composite moisture-absorbing material with good moisture absorption performance.

[0008] The precursor of the non-hydrophilic polymer aerogel obtained by the research team of this invention is a hydrophilic aerogel. However, if the precursor, i.e., the hydrophilic polymer aerogel, is used and the moisture-absorbing material is impregnated and then attached to the hydrophilic polymer aerogel, it is found that a composite moisture-absorbing material with good moisture-absorbing properties cannot be obtained. This is because, during the impregnation process, the hydrophilic polymer aerogel collapses and the pores are blocked, so the material with the target properties cannot be obtained.

[0009] The research team of this invention initially believed that the polymer aerogel was not suitable as a skeleton material for composite moisture-absorbing materials. Unexpectedly, the inventors of this invention obtained another composite moisture-absorbing material (i.e., the aerogel composite material of this invention). This aerogel composite material also uses the aforementioned hydrophobic polymer aerogel as the skeleton material and a water-soluble moisture-absorbing material as the moisture-absorbing material. During the preparation of the hydrophobic polymer aerogel, the water-soluble moisture-absorbing material is blended with the moisture-absorbing material, thereby ensuring that the water-soluble moisture-absorbing material is uniformly distributed on the hydrophobic polymer aerogel. Even more surprisingly, the moisture-absorbing performance of this aerogel composite material not only did not decrease, but also exhibited excellent moisture-absorbing properties.

[0010] The water absorption capacity is greater than 0.5 g / g in 24 hours under the conditions of 25°C and 40% RH; greater than 0.7 g / g in 24 hours under the conditions of 25°C and 60% RH; and greater than 0.9 g / g in 24 hours under the conditions of 25°C and 80% RH. Preferably, the water absorption capacity is greater than 1.3 g / g in 24 hours under the conditions of 25°C and 40% RH; greater than 1.6 g / g in 24 hours under the conditions of 25°C and 60% RH; and greater than 2.5 g / g in 24 hours under the conditions of 25°C and 80% RH. More preferably, the water absorption capacity is greater than 1.7 g / g in 24 hours under the conditions of 25°C and 40% RH; greater than 2.3 g / g in 24 hours under the conditions of 25°C and 60% RH; and greater than 3.9 g / g in 24 hours under the conditions of 25°C and 80% RH.

[0011] It is evident that the aerogel composite material of the present invention has a rapid moisture absorption effect, and its moisture absorption ratio is much higher than that of existing materials. Moreover, the aerogel composite material can be regenerated at a lower temperature after use, and can also be recycled and reprocessed for reuse, which is in line with the concept of circular economy development and represents a major breakthrough in the field of moisture-absorbing materials.

[0012] To achieve the aforementioned objective, a first aspect of the present invention is to provide an aerogel composite material, comprising a polymer aerogel and a hygroscopic material distributed on the polymer aerogel; the hygroscopic material is a water-soluble hygroscopic material; the polymer aerogel contains structural units of maleic anhydride groups and maleimide groups; based on a total weight of 100 wt% for the polymer aerogel and the hygroscopic material, the content of the hygroscopic material in the aerogel composite material is not less than 10 wt%; wherein the structure of the maleic anhydride groups is as follows: The structure of the maleimide group is:

[0013] According to the present invention, based on the total weight of the polymer aerogel and the hygroscopic material as 100 wt%, the content of the hygroscopic material in the aerogel composite material is not less than 10 wt%; the content of the hygroscopic material in the aerogel composite material can be selected within a wide range, for example, 10 wt%, 12 wt%, 14 wt%, 16 wt%, 18 wt%, 25 wt%, 30 wt%, 40 wt%, 50 wt%, 60 wt%, 70 wt%, 75 wt%... and any two values ​​or any range of any two values.

[0014] In a preferred embodiment of the present invention, based on a total weight of 100wt% of the polymer aerogel and the moisture-absorbing material, the content of the polymer aerogel in the aerogel composite material is 25-70wt%, and the content of the moisture-absorbing material is 30-75wt%.

[0015] More preferably, based on the total weight of the polymer aerogel and the moisture-absorbing material being 100 wt%, the content of the polymer aerogel in the aerogel composite material is 30-70 wt%, and the content of the moisture-absorbing material is 30-70 wt%.

[0016] According to the present invention, more preferably, based on the total weight of the polymer aerogel and the moisture-absorbing material as 100 wt%, the content of the moisture-absorbing material in the aerogel composite material is 30-70 wt%, for example 30 wt%, 40 wt%, 50 wt%, 60 wt%, 70 wt%, and any two values ​​or any range of any two values.

[0017] According to the present invention, the molar proportion of structural units containing maleic anhydride groups in the polymer of the polymer aerogel can be selected within a wide range. In a preferred embodiment of the present invention, with the total molar amount of structural units containing maleic anhydride groups and structural units containing maleimide groups as 100%, the molar proportion of structural units containing maleic anhydride groups in the polymer is 30%-90%, preferably 50%-80%.

[0018] In a preferred embodiment of the present invention, the polymer aerogel is soluble in ammonia water at 0-150°C to form a polymer aqueous solution; preferably, the polymer aqueous solution is pre-frozen, freeze-dried, and heat-treated to recover the polymer aerogel. Based on this, the aerogel composite material of the present invention can be conveniently and environmentally recycled.

[0019] In a preferred embodiment of the present invention, the polymer aerogel is a three-dimensional porous material.

[0020] In a preferred embodiment of the present invention, the density of the polymer aerogel is 10-100 kg / m³. 3The preferred value is 15-75 kg / m³. 3 Specifically, for example, 15kg / m 3 35kg / m 3 45kg / m 3 55kg / m 3 65kg / m 3 75kg / m 3 , and any two values ​​or any interval of any two values.

[0021] The inventors of this invention have discovered that the polymer aerogel exhibits fluorescence when copolymerized with monomers containing benzene rings, and the photoluminescence intensity of the composite material with this polymer aerogel as its backbone decreases after moisture absorption. For example, when the polymer aerogel is a styrene-maleic anhydride-maleimide copolymer aerogel, the aerogel composite material exhibits photoluminescence properties, emitting light with a wavelength of 400-650 nm under light excitation at a wavelength of 300-500 nm, and the photoluminescence intensity of the composite material with this polymer aerogel as its backbone decreases after moisture absorption. This allows for visual monitoring of the water absorption of dehumidifying aerogel materials.

[0022] In a preferred embodiment of the present invention, the static water contact angle of the polymer aerogel is 100° or more, preferably 110° or more, and more preferably 135° or more.

[0023] In a preferred embodiment of the present invention, the polymer aerogel is insoluble in water. Preferably, after soaking the polymer aerogel in water at 20-40°C for 24 hours, more preferably for 72 hours, and even more preferably for 168 hours, it will not dissolve to form an aqueous polymer solution. The polymer aerogel of the present invention has the characteristics of superoleophilicity and hydrophobicity.

[0024] In a preferred embodiment of the invention, the polymer is a linear copolymer. More preferably, the side chains of the linear copolymer contain maleic anhydride groups and maleimide groups.

[0025] According to the present invention, the polymer can be selected from a wide range of sources. In a preferred embodiment of the present invention, the polymer is derived from a polymer raw material having one or more of the structural units having maleic anhydride, maleimide, maleic acid and ammonium salt, maleamic acid and ammonium salt groups.

[0026] In this invention, maleic acid and ammonium salt groups, maleamic acid and ammonium salt groups refer to In the formula, M may be the same or different, each representing a hydroxyl, amino, or ammonium (-ONH4). In this invention, the polymer raw material includes, but is not limited to, copolymers of polymeric monomers having one or more of the following groups: maleic anhydride, maleimide, maleic acid and its ammonium salt, maleamic acid and its ammonium salt, and olefin monomers; for example, this invention can also be achieved when the polymer raw material is a copolymer such as styrene-maleic anhydride-vinyl silicone oil. The copolymers of polymeric monomers having one or more of the following groups—maleic anhydride, maleimide, maleic acid and its ammonium salt, maleamic acid and its ammonium salt, and olefin monomers—have lower raw material costs.

[0027] In a more preferred embodiment of the present invention, the polymer raw material is a copolymer of a polymeric monomer having one or more of the following groups: maleic anhydride, maleimide, maleic acid and ammonium salt, maleamic acid and ammonium salt groups, and an olefinic monomer.

[0028] In a further preferred embodiment of the present invention, the olefin monomer is at least one selected from α-methylstyrene, styrene, isobutylene, and vinyl acetate.

[0029] As an example, the polymer raw materials described in this invention include, but are not limited to, at least one of styrene-maleic anhydride copolymer, styrene-maleic anhydride vinyl silicone oil copolymer, and maleic anhydride isobutylene copolymer.

[0030] Preferably, the moisture-absorbing material in this invention is uniformly distributed on the backbone of the polymer aerogel. Uniform distribution can reduce the agglomeration of the moisture-absorbing material, thereby obtaining a moisture-absorbing material with a small particle size.

[0031] Preferably, the particle size of the moisture-absorbing material is no greater than 1000 nm, and more preferably no greater than 800 nm. Small particle size allows for a larger specific surface area. Compared to larger crystalline particles in moisture-absorbing materials, the moisture-absorbing material in this invention is uniformly distributed within the aerogel, resulting in a larger specific surface area and thus increasing its moisture absorption capacity.

[0032] Preferably, in this invention, the particle size range of the hygroscopic material in the aerogel composite material is below 500 nm, for example, 10-500 nm, 10-300 nm, 10-250 nm, or 10-200 nm, which further increases the contact area between the hygroscopic material and the gas. The porous structure provided by the aerogel skeleton brings better dispersibility to the hygroscopic material. The hygroscopic material with a small particle size has a larger specific surface area, and the hygroscopic material dispersed in the aerogel will not agglomerate due to water absorption, so that it can maintain its original hygroscopic performance, giving the composite aerogel material superior hygroscopic performance.

[0033] According to the present invention, the moisture-absorbing material is a water-soluble moisture-absorbing material. In a preferred embodiment of the present invention, the moisture-absorbing material is a water-soluble salt moisture-absorbing material, preferably a monovalent cationic salt moisture-absorbing material, more preferably an alkali metal salt moisture-absorbing material, even more preferably at least one of alkali metal halide salts, alkali metal sulfates, alkali metal acetates, alkali metal formates, alkali metal silicates, and alkali metal fluorosilicates, and even more preferably at least one of lithium chloride, potassium formate, lithium bromide, lithium sulfate, potassium sulfate, lithium acetate, sodium silicate, sodium fluorosilicate, and sodium sulfate; most preferably at least one of lithium chloride and potassium formate.

[0034] According to the present invention, "halogenated" in the above-mentioned alkali metal halide salts refers to a halide anion, and the halogen can be selected from at least one of fluorine, chlorine, bromine and iodine.

[0035] According to the present invention, the alkali metal may be selected from at least one of lithium, sodium, potassium, rubidium, cesium, and francium.

[0036] According to the present invention, considering that potassium formate is cheaper and its moisture absorption performance can meet application requirements, potassium formate is also a more preferred embodiment of the present invention. When potassium formate is used as the moisture-absorbing material, the aerogel composite material obtained by the present invention has better moisture absorption performance than potassium formate and its composite materials, as described above, and has also achieved unexpected technical effects.

[0037] According to the present invention, the dehumidification effect is most obvious when lithium chloride is used as the moisture-absorbing material.

[0038] According to the present invention, preferably, the aerogel composite material has an average particle size of less than 10 mm and an average particle size of less than 5 mm.

[0039] In a further preferred embodiment of the present invention, the aerogel composite material has the following properties: water absorption greater than 0.5 g / g after 24 hours at 25°C and 40% RH; water absorption greater than 0.7 g / g after 24 hours at 25°C and 60% RH; and water absorption greater than 0.9 g / g after 24 hours at 25°C and 80% RH. Preferably, water absorption greater than 1.3 g / g after 24 hours at 25°C and 40% RH. g; the water absorption capacity is greater than 1.6 g / g in 24 hours under conditions of 25°C and 60% RH; the water absorption capacity is greater than 2.5 g / g in 24 hours under conditions of 25°C and 80% RH; more preferably, the water absorption capacity is greater than 1.7 g / g in 24 hours under conditions of 25°C and 40% RH, greater than 2.3 g / g in 24 hours under conditions of 25°C and 60% RH, and greater than 3.9 g / g in 25°C and 80% RH.

[0040] Experiments have shown that, preferably, the aerogel composite material exhibits a water absorption capacity greater than 1.5 g / g after 8 hours at 25°C and 40% RH, greater than 2.0 g / g after 8 hours at 60% RH, and greater than 3.0 g / g after 8 hours at 80% RH. The aerogel composite material of this invention not only possesses high moisture absorption performance but also high moisture absorption efficiency.

[0041] In a preferred embodiment of the present invention, the aerogel composite material is prepared by reacting a polymer raw material containing at least one of the structural units containing maleic anhydride, maleimide, maleic acid and ammonium salt, maleamic acid and ammonium salt groups with ammonia water under a closed condition to obtain a polymer aqueous solution; then the polymer aqueous solution is mixed with the hygroscopic material, and then pre-frozen, freeze-dried, and heat-treated to dehydrate and remove ammonia.

[0042] According to the above technical solution, the aerogel composite material of the present invention, which can be used for dehumidification, has a porous structure, strong moisture absorption capacity, and is renewable. Furthermore, it can be recycled after processing, exhibiting advantages of being green and efficient compared to traditional moisture-absorbing materials.

[0043] Regeneration involves evaporating the moisture in a moisture-absorbing material at a certain temperature, allowing it to regain its moisture-absorbing capacity.

[0044] Recycling refers to the further reuse of composite materials when their performance after regeneration is still insufficient to meet requirements. In this invention, the aerogel composite material, compared to traditional hygroscopic materials, can not only be recycled, but the recycled composite material also retains performance comparable to the original fresh aerogel composite material, thus achieving circular utilization.

[0045] For example, desiccants in everyday medicine bottles and food products are solid dehumidifying materials, and they are also used in chemical and medical fields. For instance, a polypropylene plant has a drying tank containing solid dehumidifying materials (such as molecular sieves) to remove water from propylene gas. The aerogel composite material in this invention has high moisture absorption (dehumidification) performance, which can reduce the amount of composite material used and improve drying (dehumidification) efficiency, especially in industrial applications, where it has significant advantages.

[0046] The desiccant composite material for dehumidification described in this invention is regenerable. Regeneration refers to the complete desorption of absorbed moisture by the aerogel composite material after it has absorbed moisture. The regeneration conditions for the aerogel composite material in this invention can adopt the regeneration conditions for solid hygroscopic materials in the prior art, or a lower regeneration temperature can be used. Preferably, the regeneration process involves storing the material in an environment with a temperature above 80°C and a humidity below 20% for at least 8 hours; more preferably, it involves storing the material in an environment with a temperature above 100°C and a humidity below 20% for at least 8 hours. The regeneration conditions for the aerogel composite material in this invention are more demanding, making it easier to reuse in applications.

[0047] The second aspect of the present invention is to provide a method for preparing the aerogel composite material described in the first aspect, comprising reacting a polymer raw material containing at least one of the structural units of maleic anhydride, maleimide, maleic acid and ammonium salt, maleamic acid and ammonium salt groups with ammonia water under closed conditions to obtain a polymer aqueous solution; then mixing the polymer aqueous solution with the hygroscopic material, and then subjecting it to pre-freezing, freeze drying, and heat treatment for dehydration and deammoniation to obtain the aerogel composite material.

[0048] As mentioned earlier, the preparation of composite aerogel hygroscopic materials in the prior art involves two to three steps: first, preparing the aerogel; second, impregnating the aerogel in an aqueous solution of the hygroscopic material, followed by drying to obtain the composite aerogel. However, the polymer aerogel of this invention has strong hydrophobic properties, making it impossible to introduce the hygroscopic material onto the polymer aerogel framework using traditional impregnation methods. If a hydrophilic polymer aerogel precursor is used for impregnation, the surface of the aerogel precursor will collapse, and even if the subsequent preparation steps are the same, aerogel composite materials with good hygroscopic properties cannot be obtained.

[0049] Traditional impregnation methods can introduce hygroscopic materials into non-hydrophobic porous materials, such as silica gel and molecular sieves, but they cannot achieve a low particle size for the hygroscopic material. For example, in the prior art, when silica gel and molecular sieves are used as hygroscopic materials, the particle size is very large, and the hygroscopic capacity is lower than that of the material prepared by this method.

[0050] This invention eliminates the need for preparing a framework material followed by impregnation of the hygroscopic material. Instead, it employs a one-step molding method to prepare a composite material with nanoscale dispersion of the hygroscopic material. This one-step method is simpler, uses no organic solvents, and is more environmentally friendly. The method is simple and easy to implement, making it suitable for preparing low-cost aerogel composite materials. Furthermore, the hygroscopic material in the aerogel composite material prepared using this method can be uniformly distributed on the aerogel framework, promoting uniform dispersion and preventing agglomeration.

[0051] Because the hygroscopic material undergoes a dissolution and dispersion process, its crystal diameter on the aerogel framework is extremely small (the average particle size of the hygroscopic material dispersed on the aerogel framework is less than 30 nm, preferably less than 20 nm), effectively increasing its contact area with air. The porous structure provided by the aerogel framework also contributes to its better dispersibility. By obtaining nanoscale hygroscopic materials through a one-step molding method, the composite aerogel material possesses excellent hygroscopic properties. The small particle size of the hygroscopic material results in a larger specific surface area, and the hygroscopic material dispersed in the aerogel will not agglomerate due to water absorption, thus maintaining its original hygroscopic properties.

[0052] In a preferred embodiment of the present invention, the preparation method includes the following specific steps:

[0053] (1) The polymer raw material is reacted with ammonia water under closed conditions to obtain a polymer aqueous solution;

[0054] (2) The polymer aqueous solution obtained in step (1) is mixed with the moisture-absorbing material to obtain an aqueous solution containing the moisture-absorbing material and the polymer;

[0055] (3) The aqueous solution containing the hygroscopic material and the polymer is pre-frozen and then freeze-dried to obtain the aerogel composite material precursor;

[0056] (4) The aerogel composite material precursor obtained in step (3) is subjected to heat treatment to obtain the aerogel composite material.

[0057] According to the present invention, the amounts of polymer raw materials and ammonia in step (1) can be selected within a wide range. In a preferred embodiment of the present invention, in step (1):

[0058] Based on the total mass of the reaction system (100%), the mass fraction of the polymer raw material is 0.1%-30%, preferably 0.5%-10%, more preferably 1%-5%, and based on the mass of ammonia in the ammonia water, the mass fraction of ammonia is 0.0001%-30%, preferably 0.01%-10%, more preferably 0.1%-1%, with the remainder being water.

[0059] According to the present invention, the reaction conditions in step (1) can be selected within a wide range. In a preferred embodiment of the present invention, the reaction conditions include: a reaction temperature of 0-200°C, preferably 50-150°C, more preferably 80-100°C; and / or a reaction time of 0.01-100 h, preferably 0.5-10 h, more preferably 1-5 h. The reaction pressure is not particularly limited, but is preferably carried out at atmospheric pressure.

[0060] In a preferred embodiment of the present invention, there is no specific requirement for the concentration of the moisture-absorbing material in the aqueous solution containing the moisture-absorbing material and the polymer; preferably, the ratio of the polymer and the moisture-absorbing material is within a preferred range.

[0061] Preferably, based on a total mass of 100 parts of polymer and moisture-absorbing material, the amount of polymer used is 25-70 parts and the amount of moisture-absorbing material used is 30-75 parts; more preferably, the amount of polymer used is 30-70 parts and the amount of moisture-absorbing material used is 30-70 parts.

[0062] Step (3) involves pre-freezing the aqueous solution containing the hygroscopic material and polymer obtained in step (2). This pre-freezing can be done in a mold to obtain ice blocks, or it can be prepared into small droplets for pre-freezing. When pre-freezing in a mold, the mold can be of any shape and size and can be customized according to the required aerogel. Freezing can be performed using a cold source such as a refrigerator, or using liquid nitrogen.

[0063] In a preferred embodiment of the present invention, in step (3): before pre-freezing the aqueous solution containing the hygroscopic material and the polymer, small droplets are prepared, and then the small droplets are pre-frozen. Pre-freezing the small droplets to form a small-particle-size aerogel composite material increases the specific surface area and improves the hygroscopic effect. In the present invention, the small droplets prepared before pre-freezing can be continuously fed into liquid nitrogen, for example, dripped into a container containing liquid nitrogen at a rate of 0.5 ml / min. The specific feeding speed is not particularly limited in the present invention and can be flexibly adjusted according to the cold source, including but not limited to the specific methods in the embodiments of the present invention.

[0064] When pre-freezing in a mold to obtain ice blocks, and then obtaining large pieces of aerogel composite material, it is preferable to include a step of pulverizing the obtained aerogel composite material.

[0065] Preferably, the aerogel composite material has an average particle size of less than 10 mm and an average particle size of less than 5 mm.

[0066] Specifically, the pre-freezing conditions can be conventional temperature conditions in the art, and the present invention is not particularly limited thereto.

[0067] According to the present invention, the freeze-drying conditions can be selected within a wide range, and the present invention is not particularly limited. In a preferred embodiment of the present invention, the freeze-drying conditions include: a temperature below -10°C, for example, below -20°C or below -30°C; and a vacuum degree in the freeze-drying process, which can be selected within a wide range. In a preferred embodiment of the present invention, the vacuum degree is below 1000 Pa, for example, below 100 Pa or below 10 Pa. The above freeze-drying conditions can be flexibly selected based on cost, efficiency, and the conventional operating mode of the equipment.

[0068] The freeze-drying process can utilize various existing freeze-drying equipment, such as freeze dryers, freeze spray dryers, and industrial freeze dryers.

[0069] In a preferred embodiment of the present invention, the freeze-drying conditions include: a temperature preferably below -10°C; and a vacuum degree preferably below 1000 Pa.

[0070] According to the present invention, the heat treatment conditions in step (4) can be selected within a wide range. In a preferred embodiment of the present invention, the heat treatment conditions in step (4) include: a temperature of 150-200°C, preferably 180-200°C, more preferably 150-190°C, and / or a time of 1-5 hours, preferably 2-3 hours.

[0071] In a preferred embodiment of the present invention, the polymer raw material can react with ammonia to obtain a water-soluble polymer.

[0072] As previously stated, in a preferred embodiment of the present invention, the polymer raw material is a copolymer of a polymeric monomer having one or more of the following groups: maleic anhydride, maleimide, maleic acid and ammonium salt, maleamic acid and ammonium salt groups, and an olefin monomer; more preferably, the olefin monomer includes at least one of α-methylstyrene, styrene, and isobutylene; even more preferably,

[0073] The polymer raw material is at least one of styrene-maleic anhydride copolymer, styrene-maleic anhydride vinyl silicone oil copolymer, and maleic anhydride isobutylene copolymer.

[0074] The polymer raw materials described above are all polymers that have been disclosed in the prior art. They can be obtained from commercially available polymers or prepared according to methods disclosed in the prior art.

[0075] The material of the sealed container is not particularly limited in this invention, and it can be a container made of metal, non-metal, polymer, or other materials.

[0076] The "and / or" in this invention refers to the fact that either one of the two conditions before or after "and / or" can be chosen, or both conditions can coexist.

[0077] A third aspect of the present invention is to provide a method for recycling an aerogel composite material, wherein the aerogel composite material is the aerogel composite material described in the first aspect or the aerogel composite material prepared by the preparation method described in the second aspect, and the recycling method includes mixing the aerogel composite material and / or materials containing the aerogel composite material with ammonia water under closed conditions until an aqueous solution containing a recycled polymer and a moisture-absorbing material is obtained, thereby obtaining an aqueous solution of the recycled material.

[0078] This recycling method does not require the introduction of organic solvents or high-temperature and high-pressure stirring. It only requires a certain concentration of ammonia water, preferably kept below 100 degrees Celsius, to achieve rapid and efficient recycling. This method has low energy consumption, low pollution, and high efficiency. The recycled polymer solution can be used again to obtain aerogel composite materials for dehumidification.

[0079] The method for recycling the dehumidifying aerogel composite material of the present invention is as follows: the aerogel composite material is placed in ammonia water of a certain concentration and placed in a sealed container, heated at a certain temperature until it is completely dissolved to obtain an aqueous solution.

[0080] In a preferred embodiment of the present invention, the temperature of the mixing reaction is 50-100°C, preferably 60-100°C, and / or the mixing reaction time is 0.5-5h, preferably 1-5h.

[0081] In a preferred embodiment of the present invention, the recycling method further includes pre-freezing, freeze-drying, and heat-treating the aqueous solution of the recycled material to obtain the recycled aerogel composite material.

[0082] According to the present invention, the conditions for freeze-drying can be selected within a wide range. The present invention is not particularly limited. In a preferred embodiment of the present invention, the conditions for freeze-drying include: a temperature below -10°C, for example, below -20°C or below -30°C, and / or a vacuum degree below 1000Pa, for example, below 100Pa or below 10Pa.

[0083] In a preferred embodiment of the present invention, the freeze-drying conditions include a temperature below (-10)°C.

[0084] In a preferred embodiment of the present invention, the vacuum degree is below 1000 Pa.

[0085] In a preferred embodiment of the present invention, the heat treatment conditions include:

[0086] The temperature is 150-200℃, preferably 180-200℃, and / or the time is 1-5h, preferably 2-3h.

[0087] A fourth aspect of the present invention is to provide a recycled aerogel composite material obtained by the recycling method according to the third aspect.

[0088] The performance of the recycled aerogel composite material obtained by the above method is comparable to that of the initially prepared aerogel composite material, and it can be recycled again.

[0089] The fifth aspect of the present invention is to provide the application of the aerogel composite material described in the first aspect, the aerogel composite material prepared by the preparation method described in the second aspect, or the recycled aerogel composite material described in the fourth aspect as a drying and dehumidifying material.

[0090] Compared with the prior art, the present invention has the following advantages:

[0091] The dehumidifying aerogel composite material of this invention possesses extremely strong moisture absorption capacity, achieving excellent moisture absorption under varying humidity conditions. It is regenerable and recyclable. Regeneration requires minimal conditions, and the moisture absorption capacity of the recycled material is comparable to that of the material prepared previously. The preparation process of this dehumidifying aerogel material requires no organic reagents, is simple, and is easy to implement and cost-effective.

[0092] The dehumidifying aerogel material in this invention can be recycled and reused, making it more environmentally friendly than existing moisture-absorbing materials.

[0093] Meanwhile, through the preparation method of this invention, the moisture-absorbing material is more uniformly dispersed in the skeleton, and the particle size range of the moisture-absorbing material is as low as the nanometer level, which is superior to the traditional preparation method. Attached Figure Description

[0094] Figure 1 The curves show the moisture absorption capacity of Example 1 over 24 hours under different humidity conditions. The curves show that the material prepared in Example 1 has excellent moisture absorption capacity (large moisture absorption amount and high moisture absorption efficiency).

[0095] Figure 2 This is a scanning electron microscope image of Example 1. The white substance in the image is lithium chloride, and the measured particle size is 10-250 nm.

[0096] Figure 3 The graph shows the fluorescence intensity of the composite aerogel before and after moisture absorption in Example 1 (excitation wavelength 295nm). The fluorescence intensity of the material is significantly reduced after moisture absorption.

[0097] Figure 4The image shows a scanning electron microscope (SEM) image of Example 1 and the energy dispersive spectroscopy (EDS) results of chlorine in this field of view. The white dots in the chlorine EDS image on the right represent the distribution of lithium chloride. The results demonstrate that the hygroscopic material lithium chloride is uniformly distributed, with a particle size range of 10-250 nm. Detailed Implementation

[0098] The present invention will now be described in detail with reference to specific embodiments. It should be noted that the following embodiments are only used to further illustrate the present invention and should not be construed as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the content of the present invention are still within the scope of protection of the present invention.

[0099] The experimental data in the examples were measured using the following instruments and methods:

[0100] 1. Moisture absorption capacity test: Different amounts of recyclable desiccant aerogel material were placed in a 25°C constant temperature and humidity chamber with a specific humidity level. The weight change of the aerogel material was recorded every 1 minute using an electronic balance. The water absorption capacity after moisture absorption was calculated using the formula: Water uptake = (m³ / min) w -m a ) / m a , where m w The mass of the aerogel material after absorbing moisture at different times is represented by m. a It is the initial mass of the aerogel material before it absorbs moisture.

[0101] 2. Particle size and distribution of hygroscopic material in aerogel: The pore and pore wall morphology of aerogel were observed using a Hitachi S-4800 scanning electron microscope (SEM). The sample surfaces were all sputter-coated with gold, and the distribution of hygroscopic material in hygroscopic aerogel was observed by energy dispersive spectroscopy.

[0102] 3. Sample fluorescence properties: The photoluminescence properties of the samples were characterized using a Horiba FL-3 fluorescence spectrometer from Japan.

[0103] 4. Method for detecting the average particle size of aerogel composite materials: Randomly select 20 composite aerogel material particles, measure the particle size using vernier calipers, and take the average value as the average particle size.

[0104] The maleic anhydride, styrene, α-methylstyrene, azobisisobutyronitrile, methanol, n-hexane, isoamyl acetate, lithium chloride, and sodium sulfate used in the following preparation examples, embodiments, and comparative examples were all purchased from Sinopharm Group and were of analytical grade; butene-1 was obtained from Yanshan Petrochemical.

[0105] Preparation example 1 (A1) of aerogel polymer:

[0106] 500 ml of isoamyl acetate was placed in a 1000 ml reactor, and nitrogen gas was purged for 40 min to remove oxygen. 49 g of maleic anhydride and 52 g of styrene were added to the flask. After complete dissolution, 0.8 g of azobisisobutyronitrile (AIBN) was added, and the water bath temperature was raised to 70 °C, and the reaction was carried out for 7 h. After the reaction, the mixture was centrifuged at 10000 rpm for 10 min, the supernatant was removed, 500 ml of methanol was added, and the mixture was stirred for 0.5 h. After centrifugation, the supernatant was removed, and this process was repeated twice. The mixture was then dried under vacuum at 140 °C for 24 h to obtain the styrene-maleic anhydride copolymer.

[0107] Preparation Example 2 (A2) of Aerogel Polymer

[0108] 500 ml of isoamyl acetate was placed in a 1000 ml reactor, and nitrogen gas was purged for 40 min to remove oxygen. 49 g of maleic anhydride, 35.4 g of α-methylstyrene, and 20.8 g of styrene were added to the flask. After complete dissolution, 0.8 g of azobisisobutyronitrile (AIBN) was added, and the water bath temperature was raised to 70 °C, and the reaction was carried out for 7 h. After the reaction, the mixture was centrifuged at 10000 rpm for 10 min, the supernatant was removed, 500 ml of methanol was added, and the mixture was stirred for 0.5 h. After centrifugation, the supernatant was removed, and this process was repeated twice. The mixture was then dried under vacuum at 140 °C for 24 h to obtain the α-methylstyrene-styrene-maleic anhydride copolymer.

[0109] Preparation Example 3 (A3) of Aerogel Polymer

[0110] 500 ml of isoamyl acetate was placed in a 1000 ml reactor, and nitrogen gas was purged for 40 min to remove oxygen. 49 g of maleic anhydride and 28 g of butene-1 were added to the reactor. 0.8 g of azobisisobutyronitrile was added, and the water bath temperature was raised to 70 °C, and the reaction was carried out for 7 h. After the reaction, the mixture was centrifuged at 10000 rpm for 10 min, the supernatant was removed, 500 ml of n-hexane was added, and the mixture was stirred for 0.5 h. After centrifugation, the supernatant was removed, and this process was repeated twice. The mixture was then vacuum dried at 140 °C for 24 h to obtain the butene-1 maleic anhydride copolymer.

[0111] Example 1

[0112] Take 4g of the copolymer obtained in Preparation Example A1, 93.2g of water and 2.8g of ammonia water with a mass fraction of 25% and add them to the reaction vessel. After closing the reaction vessel, heat it to 95°C and keep it for 1.5 hours. Then take it out to obtain an aqueous solution of aerogel material with a mass concentration of 4%.

[0113] Subsequently, 30g of aerogel material aqueous solution was mixed with 28g of 10% lithium chloride aqueous solution, and 2g of deionized water was added and mixed evenly to prepare a dehumidifying aerogel material aqueous solution.

[0114] Subsequently, using a 20ml syringe, an aqueous solution of the desiccant aerogel material was dripped at a rate of 0.5ml / min into a thermostat containing liquid nitrogen. The droplets were approximately 4mm in diameter and rapidly frozen in the liquid nitrogen. The frozen droplets were then removed and placed in a freeze dryer for freeze-drying at -30℃ and 10Pa. This yielded the precursor of the desiccant aerogel material.

[0115] The obtained desiccant aerogel material precursor was placed in a forced-air drying oven at 150°C for 4 hours to obtain the desiccant aerogel material (i.e., aerogel composite material).

[0116] In the final desiccant aerogel material, lithium chloride, the moisture-absorbing material, accounted for 70% by mass, and the aerogel material (i.e., polymer aerogel) accounted for 30% by mass. Subsequently, 10g of the desiccant aerogel material was taken for a 24-hour moisture absorption capacity test, and its microstructure was observed using a scanning electron microscope. The changes in fluorescence intensity before and after moisture absorption were tested. The results are shown below. Figures 1-4 The test results are shown in Table 1.

[0117] The average particle size of the aerogel composite material obtained in this embodiment is 2 mm.

[0118] Example 2

[0119] Take 4g of the copolymer obtained in Preparation Example A2, 93.2g of water and 2.8g of ammonia water with a mass fraction of 25% and add them to the reaction vessel. After closing the reaction vessel, heat it to 55°C and keep it for 5 hours. Then take it out to obtain an aqueous solution of aerogel material with a mass concentration of 4%.

[0120] Subsequently, 30g of the aerogel material aqueous solution was mixed with 12g of a 10% lithium chloride aqueous solution, and 18g of deionized water was added and mixed thoroughly to prepare the dehumidifying aerogel material aqueous solution. Then, using a 20ml syringe, the dehumidifying aerogel material aqueous solution was dripped at a rate of 0.5ml / min into a thermostat containing liquid nitrogen, with droplets approximately 4mm in diameter, and rapidly frozen in the liquid nitrogen. The frozen droplets were then removed and placed in a freeze dryer for freeze-drying at -30℃ and 10Pa. This yielded the dehumidifying aerogel material precursor.

[0121] The obtained desiccant aerogel precursor was treated in a forced-air drying oven at 190℃ for 1.5 hours to obtain the desiccant aerogel material with an average particle size of 2.7 mm. In the final desiccant aerogel material, lithium chloride (a moisture-absorbing material) accounted for 50% by mass, and the aerogel material accounted for 50% by mass. Subsequently, 10 g of the desiccant aerogel material was used for a 24-hour moisture absorption capacity test. The test results are shown in Table 1.

[0122] Example 3

[0123] Take 4g of the copolymer obtained in Preparation Example A3, 93.2g of water and 2.8g of ammonia water with a mass fraction of 25% and add them to the reaction vessel. After closing the reaction vessel, heat it to 65°C and keep it for 4 hours. Then take it out to obtain an aqueous solution of aerogel material with a mass concentration of 4%.

[0124] Subsequently, 30g of the aerogel material aqueous solution was mixed with 6g of a 10% lithium chloride aqueous solution, and 24g of deionized water was added and mixed thoroughly to prepare the dehumidifying aerogel material aqueous solution. Then, using a 20ml syringe, the dehumidifying aerogel material aqueous solution was dripped at a rate of 0.5ml / min into a thermostat containing liquid nitrogen, with droplets approximately 4mm in diameter, and rapidly frozen in the liquid nitrogen. The frozen droplets were then removed and placed in a freeze dryer for freeze-drying at -30℃ and 10Pa. This yielded the dehumidifying aerogel material precursor.

[0125] The obtained desiccant aerogel precursor was treated in a forced-air drying oven at 180°C for 2 hours to obtain the desiccant aerogel material with an average particle size of 3 mm. In the final desiccant aerogel material, lithium chloride, the hygroscopic material, accounted for 33.3% by mass, and the aerogel material accounted for 66.7% by mass. Subsequently, 10 g of the desiccant aerogel material was taken for a moisture absorption capacity test. The test results are shown in Table 1.

[0126] Example 4

[0127] The preparation process was the same as in Example 1, except that a 10% potassium formate aqueous solution was used instead of a 10% lithium chloride aqueous solution. The average particle size of the resulting aerogel composite material was 2 mm, and the test results are shown in Table 1.

[0128] Comparative Example 1

[0129] The preparation process was the same as in Example 1, but without the addition of lithium chloride aqueous solution, to obtain the aerogel material.

[0130] The static water contact angle of the aerogel material was determined using the German EASYDROP contact angle tester: the polymer aerogel was cut into pieces of approximately 10*10*2mm using a thin blade. 3 A thin sheet of aerogel is prepared and fixed on the operating table. During the fixing process, the sample is kept flat in the horizontal direction. Then, the glass slide is placed on the sample stage of the EASYDROP contact angle measuring instrument and fixed. The instrument is adjusted to control the volume of water droplets to 4±0.02μL. The water droplets are dropped onto the aerogel surface for 1 minute. The angle between the solid-liquid interface, through the inside of the droplet, and the vapor-liquid interface at the three-phase interface is measured. This is the static water contact angle (abbreviated as water contact angle).

[0131] Testing revealed that the static water contact angle between the aerogel material obtained in this comparative example and water was greater than 100°, indicating that the aerogel material in this comparative example is not hydrophilic.

[0132] Infrared spectroscopy and proton nuclear magnetic resonance (HMR) spectroscopy confirmed the presence of a maleimide group. In the HMR spectrum, the chemical shifts of the five hydrogen atoms on the benzene ring ranged from 7.7 to 6.0 ppm, while the chemical shifts of the hydrogen atom on the NH group of maleimide ranged from 10.2 to 9.4 ppm. Using the hydrogen atoms on the benzene ring as an internal standard, the ratio of maleimide to maleic anhydride could be calculated by integrating the hydrogen areas of maleimide and the benzene ring.

[0133] Taking the total molar amount of structural units containing maleic anhydride groups and structural units containing maleimide groups in the polymer aerogel as 100%, the molar ratio of the structural units containing maleimide groups is the maleimization rate. The maleimization rate of the aerogel material obtained in this comparative example was found to be 40.6%.

[0134] The maleimide content of the polymer aerogel in the aerogel composites obtained in each example was found to be around 40% (i.e., within the range of 40% ± 2%).

[0135] Comparative Example 2

[0136] The preparation process was the same as in Example 1, except that 0.5 g of 10% lithium chloride aqueous solution and 2 g of deionized water were added instead of the 28 g of 10% lithium chloride aqueous solution and 2 g of deionized water used in Example 1. The average particle size of the resulting aerogel composite material was 3.8 mm, and the test results are shown in Table 1.

[0137] Comparative Example 3

[0138] Using 4A molecular sieve (a molecular sieve with a pore size of approximately 0.4 nm, commonly used for drying gases and liquids; Langfang Naco New Material Technology Co., Ltd.), its 24-hour moisture absorption capacity was tested and analyzed by placing it at 25℃ under conditions of 40%RH, 60%RH, and 80%RH for 24 hours. The test results are shown in Table 1.

[0139] Comparative Example 4

[0140] Take 4g of the copolymer obtained in Preparation Example A1, 93.2g of water and 2.8g of ammonia water with a mass fraction of 25% and add them to the reaction vessel. After closing the reaction vessel, heat it to 95°C and keep it for 1.5 hours. Then take it out to obtain an aqueous solution of aerogel material with a mass concentration of 4%.

[0141] Subsequently, using a 20ml syringe, an aqueous solution of the aerogel material was dripped at a rate of 0.5ml / min into a thermostat containing liquid nitrogen. The droplets were approximately 4mm in diameter and rapidly frozen in the liquid nitrogen. The frozen droplets were then removed and placed in a freeze dryer for freeze-drying at -30℃ and 10Pa. The resulting aerogel material had an average particle size of 3.9mm.

[0142] Take 28g of a 10% lithium chloride aqueous solution and immerse the aerogel material in the solution for 1 minute. After removal, the average particle size becomes 3.4mm. Upon removal, the aerogel is found to have dissolved, and the surface pore structure collapses. After drying, 10g of the composite material (No. A) is weighed and subjected to a 24-hour moisture absorption test. The obtained composite material (No. A) has limited moisture absorption properties, as shown in Table 1.

[0143] The above composite material was treated in a forced-air drying oven at 190°C for 1.5 hours. It was found that the moisture absorption performance of the resulting composite material (No. B) was slightly lower than that of No. A.

[0144] Comparative Example 5

[0145] Take 4g of the copolymer obtained in Preparation Example A1, 93.2g of water and 2.8g of ammonia water with a mass fraction of 25% and add them to the reaction vessel. After closing the reaction vessel, heat it to 95°C and keep it for 1.5 hours. Then take it out to obtain an aqueous solution of aerogel material with a mass concentration of 4%.

[0146] Subsequently, using a 20ml syringe, an aqueous solution of the aerogel material was dripped at a rate of 0.5ml / min into a thermostat containing liquid nitrogen. The droplets were approximately 4mm in diameter and rapidly frozen in the liquid nitrogen. The frozen droplets were then removed and placed in a freeze dryer for freeze-drying at -30℃ and 10Pa. This yielded the aerogel material precursor.

[0147] The obtained desiccant aerogel material precursor was placed in a forced-air drying oven at 150°C for 4 hours to obtain the aerogel material with an average particle size of 3.9 mm.

[0148] Take 28g of a 10% (w / w) lithium chloride aqueous solution and immerse the aerogel material in the solution for 1 minute, then remove and dry. Due to the hydrophobic nature of the aerogel material, the aqueous solution did not penetrate into the interior of the aerogel material, and the average particle size was 3.9mm. Subsequently, 10g of the material was weighed for a 24-hour moisture absorption performance test. The test results are shown in Table 1.

[0149] Example 5 (Recycling and Reuse)

[0150] Weigh 5g of the material prepared in Example 1, add it to a reaction vessel along with 91.5g of water and 2.5g of ammonia solution with a mass fraction of 25%, and treat at 95°C for 3 hours to obtain the recovered desiccant aerogel material aqueous solution.

[0151] Subsequently, using a 20ml syringe, an aqueous solution of the desiccant aerogel material was dripped at a rate of 0.5ml / min into a thermostat containing liquid nitrogen. The droplets were approximately 4mm in diameter and rapidly frozen in the liquid nitrogen. The frozen droplets were then removed and placed in a freeze dryer for freeze-drying at -30℃ and 10Pa. This yielded a reusable precursor of the desiccant aerogel material.

[0152] The obtained reusable desiccant aerogel precursor was placed in a forced-air drying oven at 150°C for 4 hours to obtain the reusable desiccant aerogel material with an average particle size of 2 mm. In the final desiccant aerogel material, the hygroscopic material lithium chloride accounts for 70% by mass, and the aerogel material accounts for 30% by mass.

[0153] Subsequently, 10g of the desiccant aerogel material was taken for a 24-hour moisture absorption capacity test. The test results are shown in Table 1.

[0154] Example 6

[0155] Take 4g of the copolymer obtained in Preparation Example A1, 93.2g of water and 2.8g of ammonia water with a mass fraction of 25% and add them to the reaction vessel. After closing the reaction vessel, heat it to 95°C and keep it for 1.5 hours. Then take it out to obtain an aqueous solution of aerogel material with a mass concentration of 4%.

[0156] Subsequently, 30g of aerogel material aqueous solution was mixed with 28g of 10% lithium chloride aqueous solution, and 2g of deionized water was added and mixed evenly to prepare a dehumidifying composite aerogel material aqueous solution.

[0157] The prepared aqueous solution was then poured into an 8cm diameter glass beaker, which was then placed in a freezer. After 24 hours of freezing, the frozen solid was removed and placed in a freeze dryer for freeze drying at -30℃ and 10Pa. This yielded a precursor for a desiccant composite aerogel material.

[0158] The obtained dehumidifying composite aerogel material precursor was placed in a forced-air drying oven at 180°C for 2 hours to obtain a cylindrical dehumidifying composite aerogel material with a diameter of approximately 7.3 cm and a height of 1.1 cm.

[0159] In the final desiccant composite aerogel material, lithium chloride, the moisture-absorbing material, accounted for 70% by mass, and the aerogel material accounted for 30% by mass. Subsequently, 10g of the desiccant composite aerogel material was used for a 24-hour moisture absorption capacity test. The test results are shown in Table 1.

[0160] Example 7

[0161] The aerogel material obtained in Example 6 was crushed using a high-speed crusher to obtain composite aerogel particles with an average particle size of approximately 1 mm. Its 24-hour moisture absorption capacity was then tested. The test results are shown in Table 1.

[0162] Example 8

[0163] 10g of the composite aerogel from Example 1 was placed in an environment with 60% humidity and 25℃ for 24 hours. It was then regenerated by desorption treatment in a 100℃ oven for 1 hour, resulting in an average particle size of 2mm. After repeated moisture absorption cycles (3 cycles in total), its 24-hour moisture absorption capacity was tested. The test results are shown in Table 1.

[0164] Example 9

[0165] The moisture-absorbing composite aerogel material prepared in Example 1 was placed in a constant temperature and humidity chamber for 8 hours to test its moisture absorption capacity. The test results are shown in Table 1.

[0166] Example 10

[0167] The preparation process was the same as in Example 1, except that 2g of a 10% lithium chloride aqueous solution and 28g of deionized water were added. The average particle size of the aerogel composite material was 3.4mm. The test results are shown in Table 1.

[0168] Example 11

[0169] The preparation process was the same as in Example 1, except that 4g of a 10% lithium chloride aqueous solution was added instead of deionized water. The average particle size of the resulting aerogel composite material was 3.3mm. The test results are shown in Table 1.

[0170] Comparative Example 6

[0171] Using molecular sieve 4A from Comparative Example 4 as the moisture-absorbing material, its moisture absorption capacity was tested after being placed in a constant temperature and humidity chamber for 8 hours. The test results are shown in Table 1.

[0172] Comparative Example 7

[0173] Silica gel (TH3-500, Shandong Rushan Taihe Desiccant Co., Ltd.) was used as the moisture-absorbing material and placed in a constant temperature and humidity chamber for 8 hours to test its moisture absorption capacity. The test results are shown in Table 1.

[0174] Table 1

[0175]

[0176] As shown in Comparative Example 1, the polymer aerogel in the aerogel composite material of the present invention is hydrophobic and non-hydrophilic. As can be seen from the examples and Comparative Examples 1-5, the present invention, by using a specific hydrophobic polymer aerogel and a water-soluble hygroscopic material in a specific ratio, unexpectedly obtained an aerogel composite material with excellent hygroscopic properties, achieving unexpected technical effects.

[0177] As can be seen from Example 5, the aerogel composite material of the present invention can be recycled and reused to prepare a reusable aerogel composite material. The moisture absorption performance of the reusable aerogel composite material is comparable to that of the fresh aerogel composite material, thus realizing recycling.

[0178] As can be seen from Example 8, the aerogel composite material of the present invention has comparable moisture absorption properties after regeneration to those of fresh aerogel composite material, and exhibits high moisture absorption stability.

[0179] As can be seen from Examples 9, 6, and 7, the aerogel composite material of the present invention has stronger moisture absorption capacity and higher moisture absorption efficiency after 8 hours.

[0180] It should be noted that the embodiments described above are only for explaining the present invention and do not constitute any limitation on the present invention. The present invention has been described with reference to typical embodiments, but it should be understood that the words used therein are descriptive and explanatory terms, not limiting terms. Modifications can be made to the present invention within the scope of the claims, and revisions can be made to the present invention without departing from the scope and spirit of the present invention. Although the present invention described herein relates to specific methods, materials, and embodiments, it does not mean that the present invention is limited to the specific examples disclosed herein; on the contrary, the present invention can be extended to all other methods and applications with the same function.

[0181] All publications, patent applications, patents, and other references mentioned in this specification are incorporated herein by reference. Unless otherwise defined, all technical and scientific terms used in this specification have the meanings commonly understood by those skilled in the art. In case of conflict, the definitions in this specification shall prevail.

[0182] When this specification uses the prefixes “known to those skilled in the art,” “prior art,” or similar terms to derive materials, substances, methods, steps, apparatus, or components, the objects derived from such prefixes cover those commonly used in the art at the time of this application, but also include those that are not currently commonly used but will become generally recognized in the art as suitable for similar purposes.

[0183] The endpoints and any values ​​of the ranges disclosed in this application are not limited to the precise ranges or values; such ranges or values ​​should be understood to include values ​​close to them. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein. In principle, various technical solutions can be combined with each other to obtain new technical solutions, which should also be considered as specifically disclosed herein.

[0184] In the context of this specification, except where expressly stated otherwise, any matters or issues not mentioned shall apply directly to those known in the art without any modification.

[0185] Furthermore, any implementation described herein can be freely combined with one or more other implementations described herein, and the resulting technical solutions or technical ideas shall be regarded as part of the original disclosure or original record of the present invention, and should not be regarded as new content not disclosed or anticipated herein, unless those skilled in the art consider the combination to be obviously unreasonable.

Claims

1. An aerogel composite material, comprising a polymer aerogel and a hygroscopic material distributed on the polymer aerogel; wherein the hygroscopic material is a water-soluble hygroscopic material; The polymer aerogel contains structural units with maleic anhydride groups and structural units with maleimide groups. Based on a total weight of 100 wt% for the polymer aerogel and the hygroscopic material, the content of the hygroscopic material in the aerogel composite material is not less than 10 wt%. in, The structure of the maleic anhydride group is The structure of the maleimide group is as follows: .

2. The aerogel composite material according to claim 1, characterized in that: Based on a total weight of 100wt% for the polymer aerogel and the moisture-absorbing material, the content of the polymer aerogel in the aerogel composite material is 25-70wt%, and the content of the moisture-absorbing material is 30-75wt%.

3. The aerogel composite material according to claim 1, characterized in that: Based on a total weight of 100wt% for the polymer aerogel and the moisture-absorbing material, the content of the polymer aerogel in the aerogel composite material is 30-70wt%, and the content of the moisture-absorbing material is 30-70wt%.

4. The aerogel composite material according to claim 1, characterized in that: With the total molar amount of structural units containing maleic anhydride groups and structural units containing maleimide groups as 100%, the molar proportion of structural units containing maleic anhydride groups in the polymer is 30%-90%; and / or, The polymer aerogel is soluble in ammonia water at 0-150°C to form a polymer aqueous solution; and / or, The polymer aerogel is a three-dimensional porous material.

5. The aerogel composite material according to claim 1, characterized in that: With the total molar amount of structural units containing maleic anhydride groups and structural units containing maleimide groups as 100%, the molar proportion of structural units containing maleic anhydride groups in the polymer is 50%-80%; and / or, The polymer aerogel can be dissolved in ammonia water at 0-150℃ to form a polymer aqueous solution; the polymer aqueous solution can be recycled to obtain the polymer aerogel after pre-freezing, freeze-drying and heat treatment.

6. The aerogel composite material according to claim 1, characterized in that: The polymer is a linear copolymer.

7. The aerogel composite material according to claim 1, characterized in that: The polymer is derived from a polymer raw material having one or more of the structural units having maleic anhydride, maleimide, maleic acid and ammonium salt, maleamic acid and ammonium salt groups; the polymer raw material is a copolymer of a polymeric monomer having one or more of the polymeric anhydride, maleimide, maleic acid and ammonium salt, maleamic acid and ammonium salt groups and an olefin monomer.

8. The aerogel composite material according to claim 7, characterized in that: The olefin monomer is at least one of α-methylstyrene, styrene, isobutylene, and vinyl acetate.

9. The aerogel composite material according to any one of claims 1-8, characterized in that: The hygroscopic material is distributed on the framework of the polymer aerogel; and / or, The particle size range of the moisture-absorbing material is no greater than 1000 nm.

10. The aerogel composite material according to any one of claims 1-8, characterized in that: The particle size range of the moisture-absorbing material is no greater than 800 nm.

11. The aerogel composite material according to any one of claims 1-8, characterized in that: The moisture-absorbing material is a water-soluble salt-based moisture-absorbing material.

12. The aerogel composite material according to claim 11, characterized in that: The water-soluble salt moisture-absorbing material is a monovalent cationic salt moisture-absorbing material.

13. The aerogel composite material according to claim 12, characterized in that: The monovalent cationic salt moisture-absorbing material is an alkali metal salt moisture-absorbing material.

14. The aerogel composite material according to claim 13, characterized in that: Alkali metal salt hygroscopic materials are at least one of the following: alkali metal halide, alkali metal sulfate, alkali metal acetate, alkali metal formate, alkali metal silicate, and alkali metal fluorosilicate.

15. The aerogel composite material according to claim 13, characterized in that: Alkali metal salt moisture-absorbing materials include at least one of lithium chloride, potassium formate, lithium bromide, lithium sulfate, potassium sulfate, lithium acetate, sodium silicate, sodium fluorosilicate, and sodium sulfate.

16. The aerogel composite material according to any one of claims 1-8, characterized in that: The aerogel composite material has an average particle size of less than 10 mm; and / or, The aerogel composite material has the following properties: The water absorption is greater than 0.5 g / g in 24 hours at 25℃ and 40%RH; greater than 0.7 g / g in 24 hours at 25℃ and 60%RH; and greater than 0.9 g / g in 24 hours at 25℃ and 80%RH.

17. The aerogel composite material according to any one of claims 1-8, characterized in that: The aerogel composite material is prepared by reacting a polymer raw material containing at least one of the structural units of maleic anhydride, maleimide, maleic acid and ammonium salt, maleamic acid and ammonium salt groups with ammonia water under closed conditions to obtain a polymer aqueous solution; then mixing the polymer aqueous solution with the hygroscopic material, and then pre-freezing, freeze-drying, and heat-treating to dehydrate and remove ammonia.

18. A method for preparing an aerogel composite material according to any one of claims 1-17, comprising reacting a polymer raw material containing at least one of the structural units of maleic anhydride, maleimide, maleic acid and ammonium salt, maleamic acid and ammonium salt groups with ammonia water under closed conditions to obtain a polymer aqueous solution; then mixing the polymer aqueous solution with the hygroscopic material, and then subjecting it to pre-freezing, freeze drying, and heat treatment for dehydration and deammoniation to obtain the aerogel composite material.

19. The preparation method according to claim 18, characterized in that... Includes the following steps: (1) The polymer raw material is reacted with ammonia water under closed conditions to obtain a polymer aqueous solution; (2) The polymer aqueous solution obtained in step (1) is mixed with the moisture-absorbing material to obtain an aqueous solution containing the moisture-absorbing material and the polymer; (3) The aqueous solution containing the hygroscopic material and the polymer is pre-frozen and then freeze-dried to obtain the aerogel composite material precursor; (4) Heat-treat the aerogel composite material precursor obtained in step (3) to obtain the aerogel composite material.

20. The preparation method according to claim 19, characterized in that: In step (1): Based on the total mass of the reaction system being 100%, the mass fraction of polymer raw materials is 0.1%-30%, and based on the mass of ammonia in ammonia water, the mass fraction of ammonia is 0.0001%-30%, with the remaining component being water.

21. The preparation method according to claim 19, characterized in that: In step (1): Based on the total mass of the reaction system being 100%, the mass fraction of polymer raw materials is 0.5%-10%, based on the mass of ammonia in ammonia water, the mass fraction of ammonia is 0.01%-10%, and the remaining component is water.

22. The preparation method according to claim 19, characterized in that: In step (1): Based on the total mass of the reaction system being 100%, the mass fraction of polymer raw materials is 1%-5%, the mass fraction of ammonia in ammonia water is 0.1%-1%, and the remaining components are water.

23. The preparation method according to claim 19, characterized in that: In step (1): The reaction temperature is 0-200℃; and / or the reaction time is 0.01-100h.

24. The preparation method according to claim 19, characterized in that: In step (1): The reaction temperature is 50-150℃; and / or the reaction time is 0.5-10h.

25. The preparation method according to claim 19, characterized in that: In step (1): The reaction temperature is 80-100℃; and / or the reaction time is 1-5h.

26. The preparation method according to claim 19, characterized in that: In step (3): small droplets are prepared before pre-freezing the aqueous solution containing the hygroscopic material and polymer; and / or, The conditions for freeze drying include: a temperature below -10℃ and a vacuum degree below 1000Pa.

27. The preparation method according to claim 19, characterized in that: The heat treatment conditions in step (4) include: The temperature is 150-200℃, and / or the time is 1-5h.

28. The preparation method according to claim 19, characterized in that: The heat treatment conditions in step (4) include: The temperature is 180-200℃, and / or the time is 2-3 hours.

29. The preparation method according to claim 19, characterized in that: The heat treatment conditions in step (4) include: The temperature is 150-190℃.

30. The preparation method according to any one of claims 18-29, characterized in that: The polymer raw material is a copolymer of a polymeric monomer having one or more of the following groups: maleic anhydride, maleimide, maleic acid and ammonium salt, maleamic acid and ammonium salt groups, and an olefinic monomer.

31. The preparation method according to claim 30, characterized in that: The olefin monomer includes at least one of α-methylstyrene, styrene, and isobutylene.

32. The preparation method according to claim 30, characterized in that: The polymer raw material is at least one of styrene-maleic anhydride copolymer, styrene-maleic anhydride vinyl silicone oil copolymer, and maleic anhydride isobutylene copolymer.

33. A method for recycling an aerogel composite material, wherein the aerogel composite material is the aerogel composite material according to any one of claims 1-17 or the aerogel composite material prepared by the preparation method according to any one of claims 18-32, and the recycling method comprises mixing the aerogel composite material and / or materials containing the aerogel composite material with ammonia water under closed conditions until an aqueous solution containing the recycled polymer and the hygroscopic material is obtained, thereby obtaining an aqueous solution of the recycled material.

34. The recycling method according to claim 33, characterized in that: The temperature of the mixed reaction is 50-100℃, and / or the reaction time is 0.5-5h.

35. The recycling method according to claim 33, characterized in that: The temperature of the mixed reaction is 60-100℃, and / or the reaction time is 1-5h.

36. The recycling method according to claim 33, characterized in that: The recycling method further includes pre-freezing, freeze-drying, and heat-treating the aqueous solution of the recycled material to obtain the recycled aerogel composite material.

37. The recycling method according to claim 36, characterized in that: Freeze-drying conditions include: a temperature below -10°C; and / or a vacuum degree below 1000 Pa; and / or heat treatment conditions include: The temperature is 150-200℃, and / or the time is 1-5h.

38. The recycling method according to claim 36, characterized in that: Freeze-drying conditions include: a temperature below -10°C; and / or a vacuum degree below 1000 Pa; and / or heat treatment conditions include: The temperature is 180-200℃, and / or the time is 2-3 hours.

39. The recycled aerogel composite material obtained by the recycling method according to any one of claims 33-38.

40. The use of the aerogel composite material according to any one of claims 1-17, the aerogel composite material prepared by the preparation method according to any one of claims 18-32, or the aerogel composite material according to claim 39 as a drying or dehumidifying material.

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