Aerogel adsorbent as well as preparation method and application thereof

Abstract

The invention relates to an aerogel adsorbent as well as a preparation method and application thereof. The aerogel adsorbent is a melamine resin-inorganic hybrid aerogel or a melamine resin-inorganic hybrid carbon aerogel; the aerogel adsorbent is prepared from the following raw material components: melamine, formaldehyde, alkali and an inorganic substance precursor. The aerogel adsorbent is a melamine resin-inorganic composite material with the advantages of high specific surface area, high porosity, low density and the like, and is high in adsorption capacity and broad-spectrum adsorption performance.

Description

Technical Field

[0001] This invention relates to the field of adsorbent technology, and in particular to an aerogel adsorbent, its preparation method, and its application. Background Technology

[0002] CO2 is a greenhouse gas, and the CO2 produced by the burning of large amounts of fossil fuels is considered a major cause of global warming; SO2, NO X Acid rain is caused by gases that damage plants and many buildings; water pollution is becoming increasingly serious due to the emission of organic pollutants and their heavy metal ions. Adsorption methods have been widely used in water treatment, greenhouse gas treatment, and the treatment of harmful gases due to their simplicity, economy, and readily available materials.

[0003] Aerogels are highly porous three-dimensional (3D) materials, typically prepared via a sol-gel process and appropriate drying techniques. The main advantages of aerogel adsorbents include tunable surface chemistry, low density, high specific surface area, and a loose, porous structure. Over the past few decades, various aerogels have been developed as adsorbents using different precursors such as silica, graphene, and carbon nanotubes. However, the adsorption capacity of currently used inorganic aerogel adsorbents is limited.

[0004] Liu et al. (Liu XJ, Li HQ, Lin XY, et al. Synthesis of siloxane-modified melamine-formaldehyde microsphere and its heavy metal ions adsorption by coordination effects[J]. Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2015, 482: 491-499.) synthesized siloxane-modified melamine-formaldehyde microspheres for coordination adsorption of heavy metal ions, with an adsorption capacity of 10 mg / g for copper ions.

[0005] Therefore, designing and providing an aerogel adsorbent with high specific surface area, high porosity, low density and excellent adsorption performance has become an urgent problem to be solved. Summary of the Invention

[0006] To address the aforementioned technical problems, this invention provides an aerogel adsorbent, its preparation method, and its applications. The aerogel adsorbent is a melamine resin-inorganic composite material with advantages such as high specific surface area, high porosity, and low density. It not only possesses strong adsorption capacity but also exhibits broad-spectrum adsorption properties.

[0007] To achieve this objective, the present invention adopts the following technical solution:

[0008] In a first aspect, the present invention provides an aerogel adsorbent, wherein the aerogel adsorbent is a melamine resin-inorganic hybrid aerogel or a melamine resin-inorganic hybrid carbon aerogel.

[0009] The raw material components of the aerogel adsorbent include melamine, formaldehyde, alkali and inorganic precursors.

[0010] This invention designs the raw material components of the aerogel adsorbent by using widely available and inexpensive melamine, formaldehyde, alkali, and inorganic precursors in combination. The resulting aerogel adsorbent is a melamine resin-inorganic hybrid aerogel or melamine resin-inorganic hybrid carbon aerogel, a melamine resin-inorganic hybrid composite material with high specific surface area, high porosity, and low density. It not only has strong adsorption capacity but also broad-spectrum adsorption performance, capable of adsorbing organic pollutants and heavy metal ions in water, as well as organic / inorganic acidic gases and inorganic alkaline gases. It can also be used in the battery field, effectively meeting practical application needs and demonstrating strong practicality.

[0011] The following are preferred technical solutions of the present invention, but are not intended to limit the technical solutions provided by the present invention. The purpose and beneficial effects of the present invention can be better achieved and realized through the following preferred technical solutions.

[0012] As a preferred embodiment of the present invention, the molar ratio of melamine to formaldehyde is 1:(1.5-3.5), wherein (1.5-3.5) can be, for example, 1.5, 1.8, 2, 2.2, 2.4, 2.6, 2.8, 3 or 3.5, and specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0013] Preferably, the formaldehyde comprises a formaldehyde aqueous solution with a mass concentration of 35-40%, wherein 35-40% can be, for example, 35%, 35.5%, 36%, 36.5%, 37%, 37.5%, 38%, 38.5%, 39%, 39.5% or 40%, and specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0014] Preferably, the alkali includes a strong alkali.

[0015] Preferably, the strong base includes sodium hydroxide and / or potassium hydroxide.

[0016] Preferably, the mass ratio of the alkali to melamine is (0.015-0.06):1, wherein (0.015-0.06) can be, for example, 0.015, 0.02, 0.025, 0.03, 0.035, 0.04, 0.045, 0.05, 0.055 or 0.06, and specific values ​​between the above values. Due to space limitations and for the sake of brevity, this invention will not exhaustively list the specific values ​​included in the range.

[0017] Preferably, the mass ratio of the inorganic precursor to melamine is 1:(0.1-3.5), wherein (0.1-3.5) can be, for example, 0.1, 0.2, 0.3, 0.4, 0.5, 0.7, 1, 1.5, 2, 2.5, 3 or 3.5, and specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range, and is further preferably 1:(0.4-1.5).

[0018] In this invention, by optimizing the mass ratio of inorganic precursor to melamine, the adsorption capacity of the resulting aerogel adsorbent can be further improved. When the mass ratio of the two is low, the content of inorganic components in the resulting aerogel adsorbent is too low, which is not conducive to enhancing the adsorption effect and reducing the overall adsorption effect. When the mass ratio of the two is high, the content of inorganic components in the resulting aerogel adsorbent is too high, which is not conducive to the role of triazine rings and amino groups in melamine resin, thereby reducing the overall adsorption effect of the resulting aerogel adsorbent on the gas.

[0019] Preferably, the inorganic precursor includes any one or a combination of at least two of the following: an organosilicon source, an organotitanium source, an organozirconium source, or an inorganic sol.

[0020] Preferably, the organosilicon source includes any one or a combination of at least two of tetraethyl orthosilicate, methyl orthosilicate, methyltriethoxysilane, or methyltrimethoxysilane.

[0021] Preferably, the organic titanium source includes tetrabutyl titanate.

[0022] Preferably, the organic zirconium source includes any one or a combination of at least two of tetrabutyl zirconate, zirconium n-propoxide, zirconium isooctanoate, zirconium acetate, or zirconium propionate.

[0023] Preferably, the inorganic sol includes any one or a combination of at least two of silica sol, aluminum sol, titanium sol, or zirconium sol.

[0024] It should be noted that the inorganic sol provided in this invention can be a commercially available product or can be prepared by oneself. When the inorganic sol used is a self-made product, the preparation method used is the prior art, that is, the preparation methods of inorganic sol commonly used in the field are all applicable, including but not limited to the sol-gel method.

[0025] Preferably, the raw material components of the aerogel adsorbent further include a solvent.

[0026] Preferably, the solvent includes water.

[0027] Preferably, the mass ratio of the solvent to melamine is (5-16):1, wherein (5-16) can be, for example, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 or 16, and specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0028] Preferably, the melamine resin-inorganic hybrid aerogel includes any one or a combination of at least two of the following: melamine resin-silicon hybrid carbon aerogel, melamine resin-titanium hybrid carbon aerogel, melamine resin-zirconium hybrid carbon aerogel, melamine resin-alumina hybrid aerogel, melamine resin-silicon-titanium hybrid aerogel, or melamine resin-silicon-zirconium hybrid aerogel.

[0029] In a second aspect, the present invention employs a method for preparing an aerogel adsorbent as described in the first aspect, the method comprising the following steps:

[0030] (1) Mix melamine, formaldehyde, alkali and optional solvent, react to obtain organic precursor liquid;

[0031] (2) After cooling the organic precursor liquid in step (1), adjust the pH, add the inorganic precursor, mix and react, and then replace and dry to obtain melamine resin-inorganic hybrid aerogel.

[0032] Alternatively, the melamine resin-inorganic hybrid aerogel described in step (2) can be carbonized to obtain melamine resin-inorganic hybrid carbon aerogel.

[0033] The aerogel adsorbent preparation method provided by this invention ingeniously hybridizes melamine resin with inorganic components to form an aerogel adsorbent with high specific surface area, high porosity, and low density. The amine groups and triazine rings in the melamine resin exhibit good affinity for specific gases (such as SO2 and CO2), while the introduction of inorganic components provides more active sites, significantly improving the adsorption capacity of the resulting composite material and giving it broad-spectrum adsorption capabilities. Without carbonization, the obtained aerogel adsorbent is a melamine resin-inorganic hybrid aerogel, which can effectively adsorb organic pollutants and heavy metal ions in water. After carbonization, it can be used for the adsorption of organic / inorganic acidic gases, inorganic alkaline gases, or in the battery field. This effectively solves the problems of small specific surface area and insufficient adsorption performance of current adsorbents.

[0034] Preferably, the reaction temperature in step (1) is 70-90℃, for example, it can be 70℃, 72℃, 75℃, 78℃, 80℃, 82℃, 85℃, 88℃ or 90℃, and specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0035] Preferably, the reaction time in step (1) is 10-30 min, for example, it can be 10 min, 12 min, 15 min, 18 min, 20 min, 22 min, 25 min, 28 min or 30 min, as well as specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0036] Preferably, the cooling in step (2) includes cooling to 20-30°C, for example, 20°C, 21°C, 22°C, 23°C, 24°C, 25°C, 26°C, 27°C, 28°C, 29°C or 30°C, as well as specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0037] Preferably, step (2) involves adjusting the pH of the system to 1-1.5 using a pH adjuster. For example, the pH can be 1, 1.05, 1.1, 1.15, 1.2, 1.25, 1.3, 1.35, 1.4, 1.45 or 1.5, as well as specific values ​​between the above values. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific values ​​included in the range.

[0038] This invention uses a pH adjuster to adjust the pH of the system to 1-1.5, which can significantly shorten the gelation time, thereby improving the production efficiency. At the same time, it is beneficial to improve the adsorption performance of the obtained aerogel adsorbent for CO2.

[0039] Preferably, the pH adjuster includes hydrochloric acid and / or nitric acid.

[0040] Preferably, the mixing in step (2) is carried out under stirring.

[0041] Preferably, the mixing time in step (2) is 30-60 min, for example, it can be 30 min, 35 min, 40 min, 45 min, 50 min, 55 min or 60 min, and specific point values ​​between the above point values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific point values ​​included in the range.

[0042] Preferably, the reaction temperature in step (2) is 95-100℃, for example, it can be 95℃, 95.5℃, 96℃, 96.5℃, 97℃, 97.5℃, 98℃, 98.5℃, 99℃, 99.5℃ or 100℃, as well as specific values ​​between the above points. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0043] Preferably, the reaction time in step (2) is 1-24 h, for example, it can be 1 h, 2 h, 5 h, 8 h, 10 h, 12 h, 15 h, 18 h, 20 h, 22 h or 24 h, as well as specific point values ​​between the above point values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific point values ​​included in the range.

[0044] Preferably, the displacement treatment in step (2) is carried out in an alcohol solvent.

[0045] Preferably, the alcohol solvent includes any one or a combination of at least two of methanol, ethanol, or isopropanol.

[0046] Preferably, the number of replacement processes in step (2) is 3-5 times (for example, 3, 4 or 5 times), and the interval between two adjacent replacement processes is 24 hours.

[0047] Preferably, the drying method in step (2) includes freeze drying or supercritical drying.

[0048] Preferably, the supercritical drying includes CO2 supercritical drying or ethanol supercritical drying.

[0049] Preferably, the supercritical CO2 drying method includes drying under the protection of supercritical CO2 fluid, with an autoclave pressure of 8-15 MPa and a drying time of 5-15 h.

[0050] Wherein, 8-15 MPa can be 8 MPa, 9 MPa, 10 MPa, 11 MPa, 12 MPa, 13 MPa, 14 MPa or 15 MPa, and 5-15 h can be 5 h, 6 h, 7 h, 8 h, 9 h, 10 h, 11 h, 12 h, 13 h, 14 h or 15 h, as well as specific point values ​​between the above point values. Due to space limitations and for the sake of brevity, this invention will not exhaustively list the specific point values ​​included in the range.

[0051] This invention uses supercritical CO2 drying to replace the alcohol solvent in the three-dimensional network of the wet gel obtained after displacement treatment with CO2 to obtain an aerogel.

[0052] It should be noted that the temperature of supercritical CO2 drying in this invention is determined based on the alcohol solvent used in the actual displacement treatment. If the alcohol solvent is methanol, the temperature of supercritical CO2 drying is 40-50℃; if the alcohol solvent is ethanol, the temperature of supercritical CO2 drying is 40-60℃; if the alcohol solvent is isopropanol, the temperature of supercritical CO2 drying is 50-80℃.

[0053] Among them, 40-50℃ can be 40℃, 41℃, 42℃, 43℃, 44℃, 45℃, 46℃, 47℃, 48℃, 49℃ or 50℃; 40-60℃ can be 40℃, 42℃, 45℃, 48℃, 50℃, 52℃, 55℃, 58℃ or 60℃; 50-80℃ can be 50℃, 55℃, 60℃, 65℃, 70℃, 75℃ or 80℃; and specific point values ​​between the above point values. Due to space limitations and for the sake of brevity, this invention will not exhaustively list the specific point values ​​included in the range.

[0054] Preferably, the temperature for supercritical drying of ethanol is 260-320℃, the pressure in the autoclave is 8-12 MPa, and the reaction time is 5-15 h.

[0055] Wherein, 260-320℃ can be 260℃, 270℃, 280℃, 290℃, 300℃, 310℃ or 320℃, 8-12MPa can be 8 MPa, 8.5 MPa, 9 MPa, 9.5 MPa, 10 MPa, 10.5 MPa, 11 MPa, 11.5 MPa or 12 MPa, 5-15 h can be 5 h, 6 h, 7 h, 8 h, 9 h, 10 h, 11 h, 12 h, 13 h, 14 h or 15 h, and the specific point values ​​between the above point values ​​are not exhaustively listed in this invention due to space limitations and for the sake of brevity.

[0056] Preferably, the carbonization process is carried out in a tubular furnace.

[0057] Preferably, the carbonization process is carried out under a protective gas atmosphere.

[0058] Preferably, the protective gas includes any one or a combination of at least two of nitrogen, argon, or helium.

[0059] Preferably, the carbonization temperature is 500-800℃, for example, it can be 500℃, 550℃, 600℃, 650℃, 700℃, 750℃ or 800℃, and specific values ​​between the above points. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0060] Preferably, the carbonization treatment time is 1-3 hours, for example, it can be 1 hour, 1.2 hours, 1.5 hours, 1.8 hours, 2 hours, 2.2 hours, 2.5 hours, 2.8 hours or 3 hours, as well as specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0061] Preferably, the preparation method of the aerogel adsorbent provided by the present invention specifically includes the following steps:

[0062] (1) After mixing melamine, formaldehyde, alkali and optional solvent, react at 70-90℃ for 10-30 min to obtain organic precursor solution;

[0063] (2) After cooling the organic precursor liquid in step (1) to 20-30℃, the pH of the system is adjusted to 1-1.5 using a pH adjuster. Inorganic precursor is added, and after mixing for 30-60 min, the mixture is reacted at 95-100℃ for 1-24 h. After alcohol solvent replacement and drying, melamine resin-inorganic hybrid aerogel is obtained.

[0064] Alternatively, the melamine resin-inorganic hybrid aerogel described in step (2) can be carbonized at 500-800℃ for 1-3 hours to obtain melamine resin-inorganic hybrid carbon aerogel.

[0065] Thirdly, the present invention provides an application of an aerogel adsorbent prepared by the preparation method described in the second aspect in the adsorption of organic pollutants, adsorption of metal ions, adsorption of gases, or battery preparation.

[0066] Compared with the prior art, the present invention has at least the following beneficial effects:

[0067] (1) This invention designs the raw material components of the aerogel adsorbent by using widely available and inexpensive melamine, formaldehyde, alkali and inorganic precursors in combination, so that the resulting aerogel adsorbent is a melamine resin-inorganic hybrid aerogel or melamine resin-inorganic hybrid carbon aerogel with high specific surface area, high porosity and low density. It not only has strong adsorption capacity, but also has broad-spectrum adsorption performance. It can adsorb organic pollutants and heavy metal ions in water, as well as organic / inorganic acidic gases and inorganic alkaline gases. It can also be used in the battery field, which can well meet the practical application needs and has strong practicality.

[0068] (2) The aerogel adsorbent provided by the present invention has a high specific surface area (568-1219 m²). 2 High porosity (≥90%) and excellent adsorption performance (the aerogel adsorbent obtained without carbonization can adsorb up to 86 mg / g of copper ions and up to 608 mg / g of tetracycline; the aerogel adsorbent obtained after carbonization has excellent selective adsorption effect on CO2, with an adsorption capacity of 3.8-6.5 mmol / g). Attached Figure Description

[0069] Figure 1 A schematic diagram illustrating the preparation and application of the aerogel adsorbent provided by this invention;

[0070] Figure 2 A photograph of the melamine resin-inorganic hybrid aerogel provided in Example 1;

[0071] Figure 3 The image is a scanning electron microscope (SEM) image of the melamine resin-inorganic hybrid aerogel provided in Example 1.

[0072] Figure 4 The adsorption curve of the melamine resin-inorganic hybrid carbon aerogel provided in Example 1. Detailed Implementation

[0073] To facilitate understanding of the present invention, the following embodiments are provided. Those skilled in the art should understand that these embodiments are merely illustrative and should not be construed as limiting the scope of the invention.

[0074] Unless otherwise specified, the materials and equipment involved in the following detailed embodiments are all conventional materials and equipment in the art and will not affect the technical effects of the present invention.

[0075] Unless otherwise specified, all reagents and raw materials used in the following examples and comparative examples are commercially available products. Some raw material information is as follows:

[0076] Aluminum sol: The mass content of aluminum oxide is 30%; it is prepared and used immediately. It is prepared by dissolving aluminum isopropoxide in isopropanol, slowly adding hydrochloric acid (0.01 mol / L aqueous solution), and aging at 70°C to make the sol particles uniform.

[0077] Silicon-titanium mixed sol: The total mass content of oxides is 30%, and the molar ratio of silicon atoms to titanium atoms is 3:1; it is prepared and used immediately. The silica sol is prepared by mixing tetraethyl orthosilicate, ammonia, and ethanol, and the pH is adjusted to 2 with hydrochloric acid (0.1 mol / L alcohol solution). Then, tetraethyl titanate is added dropwise under stirring to prepare the sol.

[0078] The schematic diagram of the preparation and application of the aerogel adsorbent provided by this invention is shown below. Figure 1 As shown.

[0079] Example 1

[0080] This embodiment provides an aerogel adsorbent and its preparation method, the preparation method comprising the following steps:

[0081] (1) Melamine (3.5 g, 0.028 mol), 37% formaldehyde aqueous solution (6.9 mL, 0.094 mol), sodium hydroxide 0.2 g and water (50 mL, 50 g) were mixed and reacted at 80℃ for 20 min to obtain a colorless and transparent organic precursor solution;

[0082] (2) Cool the organic precursor solution described in step (1) to 25°C, adjust the pH to 1.2 using concentrated nitric acid with a mass concentration of 68%, add 7.9 g of tetraethyl orthosilicate, stir for 40 min, and react at 95°C for 3 h to obtain a white gel. Replace the gel with ethanol every 24 h for 4 replacements, and then dry it at 50°C and 15 MPa using supercritical CO2 drying for 9 h to obtain a melamine resin-silica hybrid aerogel (its physical image is shown below). Figure 2 As shown, the scanning electron microscope image is as follows: Figure 3 (as shown)

[0083] The melamine resin-silica hybrid aerogel obtained in step (2) was placed in a tube furnace and carbonized at 600°C under a nitrogen atmosphere for 2 h to obtain melamine resin-silica hybrid carbon aerogel.

[0084] like Figure 4 As shown, the aerogel adsorbent provided in this embodiment is a melamine resin-silica hybrid carbon aerogel, which can adsorb CO2 up to 6.5 mmol / g at 0.9 bar, and N2 at 0.2 mmol / g, which means it has excellent selective adsorption effect on CO2.

[0085] Example 2

[0086] This embodiment provides an aerogel adsorbent and its preparation method, the preparation method comprising the following steps:

[0087] (1) Melamine (3.5 g, 0.028 mol), 35% formaldehyde aqueous solution (3.2 mL, 0.042 mol), sodium hydroxide 0.06 g and water (35 mL, 35 g) were mixed and reacted at 70℃ for 30 min to obtain a colorless and transparent organic precursor solution;

[0088] (2) Cool the organic precursor liquid described in step (1) to 20°C, adjust the pH to 1 with concentrated hydrochloric acid with a mass concentration of 36%, add 8 g of aluminum sol, stir for 30 min, react at 98°C for 2 h to obtain a gel, use ethanol for replacement treatment, replace the ethanol every 24 h, after 3 replacement treatments, dry at 300°C and 10 MPa using supercritical ethanol drying for 10 h to obtain melamine resin-alumina hybrid aerogel;

[0089] The melamine resin-alumina hybrid aerogel obtained in step (2) was placed in a tube furnace and carbonized at 500°C under a nitrogen atmosphere for 4 h to obtain melamine resin-alumina hybrid carbon aerogel.

[0090] Example 3

[0091] This embodiment provides an aerogel adsorbent and its preparation method, the preparation method comprising the following steps:

[0092] (1) Melamine (3.5000 g, 0.028 mol), 40% formaldehyde aqueous solution (4.8 mL, 0.07 mol), potassium hydroxide 0.15 g and water (18 mL, 18 g) were mixed and reacted at 90℃ for 10 min to obtain a colorless and transparent organic precursor solution;

[0093] (2) Cool the organic precursor liquid described in step (1) to 30°C, adjust the pH to 1.4 with concentrated nitric acid with a mass concentration of 68%, add 4.58 g of zirconium acetate, stir for 60 min, and react at 100°C for 1 h to obtain a gel. Use isopropanol for replacement treatment, replace the isopropanol every 24 h, and after 5 replacement treatments, dry it at 65°C and 12 MPa using CO2 supercritical drying for 5 h to obtain melamine resin-zirconia hybrid aerogel.

[0094] The melamine resin-zirconia hybrid aerogel obtained in step (2) was placed in a tube furnace and carbonized at 800°C under a nitrogen atmosphere for 1 h to obtain melamine resin-zirconia hybrid carbon aerogel.

[0095] Example 4

[0096] This embodiment provides an aerogel adsorbent and its preparation method. The only difference between this embodiment and Example 1 is that the carbonization step is not performed. All other raw materials, contents and preparation methods are the same as in Example 1, resulting in a melamine resin-silica hybrid aerogel.

[0097] Example 5

[0098] This embodiment provides an aerogel adsorbent and its preparation method. The only difference between this embodiment and Example 1 is that the CO2 supercritical drying method in step (2) of Example 1 is replaced by freeze drying, and the carbonization step is not performed. The other raw materials, contents and preparation methods are the same as in Example 1, and melamine resin-silica hybrid aerogel is obtained.

[0099] Example 6

[0100] This embodiment provides an aerogel adsorbent and its preparation method. The only difference between this embodiment and Example 1 is that the tetraethyl orthosilicate in step (2) of Example 1 is replaced with silicon-titanium mixed sol (10 mL). The other raw materials, contents and preparation methods are the same as in Example 1, and melamine resin-zirconia / titanium oxide hybrid carbon aerogel is obtained.

[0101] Example 7

[0102] This embodiment provides an aerogel adsorbent and its preparation method. The only difference between this embodiment and Example 1 is that the amount of tetraethyl orthosilicate added in step (2) of Example 1 is adjusted from 7.9 g to 35 g. Other raw materials, contents and preparation methods are the same as in Example 1.

[0103] Example 8

[0104] This embodiment provides an aerogel adsorbent and its preparation method. The only difference between this embodiment and Example 1 is that the amount of tetraethyl orthosilicate added in step (2) of Example 1 is adjusted from 7.9 g to 12.5 g. Other raw materials, contents and preparation methods are the same as in Example 1.

[0105] Example 9

[0106] This embodiment provides an aerogel adsorbent and its preparation method. The only difference between this embodiment and Example 1 is that the amount of tetraethyl orthosilicate added in step (2) of Example 1 is adjusted from 7.9 g to 4.6 g. Other raw materials, contents and preparation methods are the same as in Example 1.

[0107] Example 10

[0108] This embodiment provides an aerogel adsorbent and its preparation method. The only difference between this embodiment and Example 1 is that the amount of tetraethyl orthosilicate added in step (2) of Example 1 is adjusted from 7.9 g to 2.34 g. Other raw materials, contents and preparation methods are the same as in Example 1.

[0109] Example 11

[0110] This embodiment provides an aerogel adsorbent and its preparation method. The only difference between this embodiment and Example 1 is that the amount of tetraethyl orthosilicate added in step (2) of Example 1 is adjusted from 7.9 g to 2 g. Other raw materials, contents and preparation methods are the same as in Example 1.

[0111] Example 12

[0112] This embodiment provides an aerogel adsorbent and its preparation method. The only difference between this embodiment and Example 1 is that the amount of tetraethyl orthosilicate added in step (2) of Example 1 is adjusted from 7.9 g to 1 g. Other raw materials, contents and preparation methods are the same as in Example 1.

[0113] Example 13

[0114] This embodiment provides an aerogel adsorbent and its preparation method, the preparation method comprising the following steps:

[0115] (1) Melamine (3.5 g, 0.028 mol), 37% formaldehyde aqueous solution (6.9 mL, 0.094 mol), sodium hydroxide 0.2 g and water (50 mL, 50 g) were mixed and reacted at 80℃ for 20 min to obtain a colorless and transparent organic precursor solution;

[0116] (2) Cool the organic precursor liquid described in step (1) to 25°C, adjust the pH to 1.6 with concentrated nitric acid with a mass concentration of 68%, add 7.9 g of tetraethyl orthosilicate, stir for 40 min, and react at 95°C for 5 h to obtain a white gel. Replace the gel with ethanol every 24 h. After 4 replacement treatments, dry it at 50°C and 15 MPa using supercritical CO2 drying for 9 h to obtain melamine resin-silica hybrid aerogel.

[0117] The melamine resin-inorganic hybrid aerogel obtained in step (2) was placed in a tube furnace and carbonized at 600°C under a nitrogen atmosphere for 2 h to obtain melamine resin-silica hybrid carbon aerogel.

[0118] The performance of the aerogel adsorbents provided in Examples 1-13 was tested, and the test results are shown in Table 1.

[0119] Table 1

[0120]

[0121] "-" indicates that no test was performed.

[0122] According to the test results in Table 1:

[0123] (1) As can be seen from Examples 1 to 13, the present invention, by using melamine, formaldehyde, alkali and inorganic precursors as raw materials, can produce an aerogel adsorbent with a high specific surface area (568-1219 m²). 2 With high porosity (≥90%), it is a melamine resin-inorganic hybrid aerogel when uncarbonized, which can effectively adsorb heavy metal ions and organic pollutants (adsorption capacity for copper ions can reach 86 mg / g, and adsorption capacity for tetracycline can reach 608 mg / g). After carbonization, it becomes a melamine resin-inorganic hybrid carbon aerogel, which can effectively adsorb CO2 (3.8-6.5 mmol / g).

[0124] (2) By comparing Example 1 with Examples 8-11, it can be seen that when the mass ratio of inorganic precursor to melamine is high (Example 8) or low (Example 11), the adsorption capacity of melamine resin-inorganic hybrid carbon aerogel obtained by both is significantly reduced. This indicates that by optimizing the mass ratio of inorganic precursor to melamine, the present invention can improve the adsorption effect of the obtained aerogel adsorbent (melamine resin-inorganic hybrid carbon aerogel) on CO2.

[0125] (3) By comparing Example 1 and Example 13, it can be seen that in Example 13, the pH was adjusted to 1.6 in step (2), the gelation time was longer during the preparation process, and the adsorption capacity of the obtained aerogel adsorbent for CO2 was reduced. This shows that the present invention can significantly shorten the gelation time by using a pH adjuster to adjust the pH of the system to 1-1.5, thereby improving production efficiency, and at the same time, it is beneficial to improve the adsorption performance of the obtained aerogel adsorbent for CO2.

[0126] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. An aerogel adsorbent, characterized in that, The aerogel adsorbent is a melamine resin-inorganic hybrid aerogel or a melamine resin-inorganic hybrid carbon aerogel. The raw material components of the aerogel adsorbent include melamine, formaldehyde, alkali and inorganic precursors.

2. The aerogel adsorbent according to claim 1, characterized in that, The molar ratio of melamine to formaldehyde is 1:(1.5-3.5); Preferably, the formaldehyde comprises an aqueous solution of formaldehyde with a mass concentration of 35-40%; Preferably, the alkali includes a strong alkali; Preferably, the strong base includes sodium hydroxide and / or potassium hydroxide; Preferably, the mass ratio of the alkali to melamine is (0.015-0.06):1; Preferably, the mass ratio of the inorganic precursor to melamine is 1:(0.1-3.5), more preferably 1:(0.4-1.5); Preferably, the inorganic precursor includes any one or a combination of at least two of the following: organosilicon source, organotitanium source, organozirconium source, or inorganic sol; Preferably, the organosilicon source includes any one or a combination of at least two of tetraethyl orthosilicate, methyl orthosilicate, methyltriethoxysilane, or methyltrimethoxysilane; Preferably, the organic titanium source includes tetrabutyl titanate; Preferably, the organic zirconium source includes any one or a combination of at least two of tetrabutyl zirconate, zirconium n-propoxide, zirconium isooctanoate, zirconium acetate, or zirconium propionate; Preferably, the inorganic sol includes any one or a combination of at least two of silica sol, aluminum sol, titanium sol, or zirconium sol; Preferably, the raw material components of the aerogel adsorbent further include a solvent; Preferably, the solvent includes water; Preferably, the mass ratio of the solvent to melamine is (5-16):

1.

3. A method for preparing the aerogel adsorbent as described in claim 1 or 2, the method comprising the following steps: (1) Mix melamine, formaldehyde, alkali and optional solvent, react to obtain organic precursor liquid; (2) After cooling the organic precursor liquid described in step (1), adjust the pH, add the inorganic precursor, mix and react, and then replace and dry to obtain melamine resin-inorganic hybrid aerogel. Alternatively, the melamine resin-inorganic hybrid aerogel described in step (2) can be carbonized to obtain melamine resin-inorganic hybrid carbon aerogel.

4. The preparation method according to claim 3, characterized in that, The reaction temperature in step (1) is 70-90℃; Preferably, the reaction time in step (1) is 10-30 min.

5. The preparation method according to claim 3 or 4, characterized in that, The cooling in step (2) includes cooling to 20-30°C; Preferably, step (2) involves adjusting the pH of the system to 1-1.5 using a pH adjuster; Preferably, the pH adjuster includes hydrochloric acid and / or nitric acid.

6. The preparation method according to any one of claims 3-5, characterized in that, The mixing in step (2) is carried out under stirring; Preferably, the mixing time in step (2) is 30-60 min; Preferably, the reaction temperature in step (2) is 95-100℃; Preferably, the reaction time in step (2) is 1-24 h.

7. The preparation method according to any one of claims 3-6, characterized in that, The displacement treatment in step (2) is carried out in an alcohol solvent; Preferably, the alcohol solvent includes any one or a combination of at least two of methanol, ethanol, or isopropanol; Preferably, the number of replacement treatments in step (2) is 3-5 times, and the interval between two adjacent replacement treatments is 24 hours; Preferably, the drying method in step (2) includes freeze-drying or supercritical drying; Preferably, the supercritical drying includes CO2 supercritical drying or ethanol supercritical drying.

8. The preparation method according to any one of claims 3-7, characterized in that, The carbonization process is carried out under a protective gas atmosphere; Preferably, the protective gas includes any one or a combination of at least two of nitrogen, argon, or helium; Preferably, the carbonization temperature is 500-800℃; Preferably, the carbonization process takes 1-3 hours.

9. The preparation method according to any one of claims 3-8, characterized in that, The preparation method includes the following steps: (1) After mixing melamine, formaldehyde, alkali and optional solvent, react at 70-90℃ for 10-30 min to obtain organic precursor solution; (2) After cooling the organic precursor liquid described in step (1) to 20-30℃, the pH of the system is adjusted to 1-1.5 using a pH adjuster. Inorganic precursor is added, and after mixing for 30-60 min, the mixture is reacted at 95-100℃ for 1-24 h. After alcohol solvent replacement and drying, melamine resin-inorganic hybrid aerogel is obtained. Alternatively, the melamine resin-inorganic hybrid aerogel described in step (2) can be carbonized at 500-800℃ for 1-3 h to obtain melamine resin-inorganic hybrid carbon aerogel.

10. The application of an aerogel adsorbent prepared by the preparation method according to any one of claims 3-9 in the adsorption of organic pollutants, adsorption of metal ions, adsorption of gases, or battery preparation.

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