An aerogel@MOF composite material and its preparation method and application

Abstract

The present invention belongs to the field of functional materials, specifically to an aerogel@MOF composite material, its preparation method, and its application. The present invention provides an aerogel@MOF composite material, which is a composite of silica aerogel and a metal-organic framework material, wherein the metal-organic framework material is an aluminum-based MOF material or a zirconium-based MOF material. The aerogel@MOF composite material has a high specific surface area and mechanical strength, and can be effectively applied in the production of autoclaved lightweight concrete and autoclaved aerated concrete, effectively improving their lightweight, strength, durability, and thermal insulation properties.

Description

Technical Field

[0001] The present invention belongs to the field of functional materials, and specifically relates to an aerogel@MOF composite material and a preparation method and application thereof. Background Art

[0002] Aerogel refers to a lightweight nano-solid material with a nanoporous network structure and a network skeleton filled with a large amount of gaseous dispersion medium. Thanks to the special nature of its structure, aerogel materials have a wide range of uses. Silica aerogel is a three-dimensional porous network material composed of silicon dioxide (SiO2) nanoparticles. It has a porosity of up to 80%-99.8% and an extremely low density. It is one of the lightest known solid materials and is known for its ultra-low thermal conductivity. It is an excellent thermal insulation material and is widely used in spacecraft insulation layers, building energy-saving glass, and environmental governance. Its high specific surface area further expands its application potential. However, this type of material is usually brittle and lacks mechanical strength. Current research is improving its mechanical properties through composite polymers and other methods.

[0003] Amino-functionalized ionic liquids are a type of modified material that introduces amino (—NH2) functional groups into the structure of traditional ionic liquids. They are prepared by reacting γ-aminopropyltriethoxysilane with imidazole or pyridine ionic liquids.

[0004] Metal-organic framework materials (MOFs) are porous crystalline materials formed by self-assembly of metal ions or metal clusters and organic ligands through coordination bonds. MOFs have a high specific surface area, and their pore size and chemical functions can be flexibly controlled by adjusting metal nodes and ligands. Therefore, they have attracted much attention in the fields of gas adsorption, catalysis, and drug delivery. Depending on the metal nodes, MOFs can be divided into aluminum-based and zirconium-based types. Aluminum-based MOFs are based on aluminum ions and have the characteristics of low cost and high stability. For example, MIL-53 (Al) is composed of Al 3+ It is composed of terephthalic acid ligands, and its unique flexible diamond-shaped pores can undergo a reversible "breathing effect" with external conditions. Another representative material, CAU-10-H, uses 2,5-furandicarboxylic acid as a ligand to form a rigid microporous structure rich in hydroxyl groups.

[0005] Zirconium-based MOFs, using zirconium oxo clusters (Zr6O4(OH)4) as nodes, exhibit chemical stability far exceeding that of other MOFs, withstanding strong acid, base, and aqueous environments. UiO-66, a typical representative of this class of materials, is composed of zirconium oxo clusters and terephthalic acid ligands, forming an octahedral cage structure with a pore size of approximately 0.8 nm. It has widespread applications in acid catalysis, adsorption of radioactive ions from nuclear waste, and photocatalytic degradation of pollutants. Its homologue, UiO-67, uses biphenyldicarboxylic acid ligands, and its pore size can be expanded to 1.2 nm.

[0006] Autoclaved aerated concrete (AAC) is a lightweight, porous material made from siliceous materials, such as quartz sand and fly ash, and calcareous materials, such as cement and lime, with aluminum powder added as a gas-forming agent. The production process includes mixing the raw materials, aerating the concrete, cutting and pre-curing, and high-temperature, high-pressure steam curing.

[0007] Autoclaved lightweight concrete (ALC) broadly encompasses all lightweight concrete produced through the autoclaving process, but more narrowly refers to materials produced by partially replacing sand and gravel with lightweight aggregates such as ceramsite and expanded perlite. While the raw materials may still contain a small amount of aerating agent, the porosity primarily originates from the porous structure of the lightweight aggregate itself. Compared to AAC, ALC has a higher density, a higher compressive strength of 37 MPa, and a slightly higher thermal conductivity, but it still outperforms traditional concrete. Summary of the Invention

[0008] The present invention aims to provide an aerogel@MOF composite material with excellent adsorption efficiency and mechanical stability, which can be effectively applied to the production of autoclaved lightweight concrete and autoclaved aerated concrete, effectively improving the lightness, strength, durability and thermal insulation of autoclaved lightweight concrete and autoclaved aerated concrete.

[0009] To achieve the above objectives, the present invention provides an aerogel@MOF composite material, wherein the aerogel@MOF composite material is a composite of silica aerogel and a metal-organic framework material, and the metal-organic framework material is an aluminum-based MOF material or a zirconium-based MOF material.

[0010] In the above-mentioned aerogel@MOF composite material, the aluminum-based MOF material is MIL-53 (Al) or CAU-10-H; and the zirconium-based MOF material is UiO-66 or UiO-67.

[0011] On the other hand, the present invention also provides a method for preparing the above-mentioned aerogel@MOF composite material, comprising the following steps:

[0012] Step 1: preparing silica aerogel, comprising the following steps:

[0013] Step 101: mixing ethyl orthosilicate, ethanol, and deionized water in a molar ratio of 1:(3-5):(3-5), adding hydrochloric acid to adjust the pH to 2-3, and stirring and hydrolyzing for 30 minutes to obtain a hydrolyzate;

[0014] Step 102: adding methyltrimethoxysilane to the hydrolyzed product obtained in step 101, adjusting the pH to 5-6, and then allowing the mixture to stand for gelation to obtain a gel product; wherein the molar ratio of the ethyl orthosilicate to methyltrimethoxysilane is 3:2-7:3;

[0015] Step 103: soaking the gel product obtained in step 102 in an ethanol solvent, and then drying it by supercritical CO2 to obtain the silica aerogel;

[0016] Step 2: In-situ synthesis of aerogel@MOF composite material, including the following steps:

[0017] Step 201, dissolving a metal salt in an amino-functionalized ionic liquid in a mixed solvent of the amino-functionalized ionic liquid and deionized water to obtain a metal salt solution;

[0018] Step 202: dissolving the organic ligand in a mixed solvent of an amino-functionalized ionic liquid and DMF to obtain a ligand solution;

[0019] Step 203: mixing the metal salt solution obtained in step 201 and the ligand solution obtained in step 202 at a volume ratio of 1:1 to obtain a mixed solution;

[0020] Step 204: adding the silica aerogel to the mixed solution obtained in step 203 to perform a hydrothermal reaction to obtain a composite material;

[0021] Step 3: post-processing and functionalizing the composite material obtained in step 204, including the following steps:

[0022] Step 301: collecting the composite material obtained in step 204 by centrifugation, washing it alternately with DMF and ethanol, and drying it to obtain a dry composite material;

[0023] Step 302: soaking the dried composite material obtained in step 301 in a NaOH solution to obtain an activated composite material;

[0024] Step 303: Immerse the activated composite material obtained in step 302 in an ethanol solution of silane coupling agent KH-550, and grind it in a ball mill after curing to obtain an aerogel@MOF composite material.

[0025] In the above preparation method, the volume ratio of the amino-functionalized ionic liquid to deionized water in step 201 is 1:4; the volume ratio of the amino-functionalized ionic liquid to DMF in step 202 is 1:3; the mass concentration of the silane coupling agent KH-550 ethanol solution in step 303 is 1 to 3 wt%, and the curing conditions are immersion at 60 to 100° C. for 0.5 to 2 hours; the ball mill is polished at a speed of 100 to 300 rpm, the ball milling medium is zirconia beads, and the polishing time is 5 to 15 minutes.

[0026] On the other hand, an application of an aerogel@MOF composite material in preparing an autoclaved aerated or autoclaved lightweight concrete additive is provided.

[0027] On the other hand, the present invention also provides the above-mentioned additive, which is composed of the following components in percentage by mass: 25-30% aerogel@MOF composite material, 3-5% hydrogen peroxide, 3-5% polycarboxylic acid water reducer, 1.5-2% isobutyltriethoxysilane, 10-20% sodium metasilicate, 1.5-3% polypropylene fiber, 0.3-0.45% iron oxide catalyst, 0.6-1% citric acid, and 45-55% water.

[0028] The mass concentration of the above-mentioned additive, the hydrogen peroxide solution is 30%; the polycarboxylate water reducer is an alkali-resistant polycarboxylate water reducer, and the molecular weight of the polycarboxylate water reducer is 5000-20000 g / mol.

[0029] The above-mentioned additives, the polypropylene fiber is surface-modified, the modifier in the surface modification is a silane coupling agent or a titanate coupling agent, and the length of the polypropylene fiber is 3 to 12 mm.

[0030] The present invention also provides a method for preparing the above additive, comprising the following steps:

[0031] Step 1: pre-treating the additive component, comprising the following steps:

[0032] Step 101: soaking the polypropylene fiber in a 5% silane coupling agent KH-550 ethanol solution for 30 minutes, and then drying at 60° C. to obtain a modified polypropylene fiber;

[0033] Step 102: mixing the polycarboxylate water-reducing agent and silica fume in a mass ratio of 1:2, and spray-drying the mixture to prepare a polycarboxylate water-reducing agent powder having a particle size of 50 to 100 μm;

[0034] Step 103: pre-mixing the aerogel@MOF composite material and sodium metasilicate and grinding them to a particle size of 20 μm to obtain a ground dry material;

[0035] Step 104: premixing the hydrogen peroxide with citric acid and adjusting the pH to 4.5-5.0 to obtain stable hydrogen peroxide;

[0036] Step 2: Start the high-speed mixer and perform dry mixing, including the following steps:

[0037] Step 201: start the high-speed mixer, preheat it to 30° C., put the ground dry material and modified polypropylene fiber into the high-speed mixer, and mix for 20 minutes to obtain a premixed dry material;

[0038] Step 202: spray isobutyltriethoxysilane into the premixed dry material obtained in step 201, and mix for 15 minutes to obtain a completely mixed dry material;

[0039] Step 3: wet mixing the completely mixed dry materials in step 202, including the following steps:

[0040] Step 301: Heat 30% of water to 25° C., add polycarboxylate water reducer and stir until completely dissolved, inject into the high-speed mixer, and stir at a low speed of 500 rpm for 10 minutes to obtain a pre-wetted mixture;

[0041] Step 302: adding the stabilized hydrogen peroxide obtained in step 104 to the pre-moistened dry material obtained in step 301, and monitoring the temperature;

[0042] Step 303: When the temperature monitored in step 302 exceeds 30°C, add 30% water, increase the speed to 1200 rpm, and continue to monitor the temperature;

[0043] Step 304: When the temperature monitored in step 303 exceeds 30°C, add 30% water and continue stirring for 10 minutes;

[0044] Step 305: Add the iron oxide catalyst to the high-speed mixer, add the remaining water, and continue stirring to obtain the additive.

[0045] In the above method, the inlet temperature of the spray drying in step 102 is 150-180° C., the outlet temperature is 60-80° C., and the atomization pressure is 0.3-0.5 MPa.

[0046] Compared with the prior art, the technical solution provided by the present invention has at least the following beneficial effects or advantages:

[0047] The aerogel@MOF composite material provided by this invention exhibits excellent adsorption efficiency and mechanical stability. The three-dimensional nanoporous network of silica aerogel provides a high-specific-surface-area support for the in-situ growth of MOF. MOF nucleates uniformly within the aerogel pores through coordination bonds, forming a hierarchical pore structure. The micron-scale macropores of the aerogel are combined with the nanoscale micropores / mesopores of the MOF to achieve multiscale mass transfer channels.

[0048] 2. In the preparation method of aerogel@MOF composite material provided by the present invention, the silane coupling agent KH-550 introduces amino functional groups on the surface of aerogel through hydrolysis condensation reaction, and reacts with MOF metal nodes (such as Al 3+ The MOFs are then chemically bonded to the surface of the composite material (e.g., Zr6O4 clusters) to reduce interfacial defects. Subsequent ball milling further eliminates MOF agglomeration and ensures the uniformity of the composite material particles.

[0049] 3. The aerogel@MOF composite material of the present invention can effectively improve the thermal insulation performance of autoclaved aerated concrete. Its pores can act as "micro-air bags" inside the concrete, reducing the matrix density while introducing a closed-cell structure, reducing heat convection transfer, and improving thermal insulation performance. Moreover, when used as a raw material for preparing additives, MOF's high specific surface area and its surface active sites can load functional molecules (such as flame retardants or impermeability agents). Through the additive, specific functions can be introduced into the concrete matrix, realizing the multi-purpose expansion of the material.

[0050] 4. In the preparation of autoclaved aerated concrete or autoclaved lightweight concrete, the aerogel@MOF composite material provided by this invention achieves a balance between lightweight, strength, durability, and process adaptability, meeting the requirements for material performance stability and construction efficiency in industrial production. DETAILED DESCRIPTION

[0051] The technical solutions of the present invention are described below with reference to the following examples. However, the present invention is not limited to the following examples. The experimental and detection methods described in each example are conventional methods unless otherwise specified. The reagents and materials described are commercially available unless otherwise specified. The percentages in the following examples are percentages by mass unless otherwise specified. The ratios in the following examples are ratios by mass unless otherwise specified.

[0052] Example 1

[0053] This embodiment provides an aerogel@MOF composite material and a preparation method thereof;

[0054] The aerogel@MOF composite material is a composite of silica aerogel and a metal organic framework material, the metal organic framework material is an aluminum-based MOF material, and the aluminum-based MOF material is MIL-53 (Al).

[0055] The above-mentioned aerogel@MOF composite material, and its preparation method comprises the following steps:

[0056] Step 1: preparing silica aerogel, comprising the following steps:

[0057] Step 101: mixing ethyl orthosilicate, ethanol, and deionized water in a molar ratio of 1:5:5, adding hydrochloric acid to adjust the pH to 3, and stirring and hydrolyzing for 30 minutes to obtain a hydrolyzate;

[0058] Step 102: adding methyltrimethoxysilane to the hydrolyzate obtained in step 101, adjusting the pH to 6, and then allowing the mixture to stand for gelation to obtain a gel product; wherein the molar ratio of the ethyl orthosilicate to methyltrimethoxysilane is 6:4;

[0059] Step 103: soaking the gel product obtained in step 102 in an ethanol solvent, and then drying it by supercritical CO2 to obtain the silica aerogel;

[0060] Step 2: In-situ synthesis of aerogel@MOF composite material, including the following steps:

[0061] Step 201, dissolving aluminum nitrate in an amino-functionalized ionic liquid in a mixed solvent of the amino-functionalized ionic liquid and deionized water to obtain a metal salt solution;

[0062] Step 202: dissolving terephthalic acid in a mixed solvent of an amino-functionalized ionic liquid and DMF to obtain a ligand solution;

[0063] Step 203: mixing the metal salt solution obtained in step 201 and the ligand solution obtained in step 202 at a volume ratio of 1:1 to obtain a mixed solution;

[0064] Step 204: adding the silica aerogel to the mixed solution obtained in step 203 to perform a hydrothermal reaction to obtain a composite material;

[0065] Step 3: post-processing and functionalizing the composite material obtained in step 204, including the following steps:

[0066] Step 301: collecting the composite material obtained in step 204 by centrifugation, washing it alternately with DMF and ethanol, and drying it to obtain a dry composite material;

[0067] Step 302: soaking the dried composite material obtained in step 301 in a NaOH solution to obtain an activated composite material;

[0068] Step 303: Immerse the activated composite material obtained in step 302 in an ethanol solution of silane coupling agent KH-550, and grind it in a ball mill after curing to obtain an aerogel@MOF composite material.

[0069] In the above preparation method, the volume ratio of the amino-functionalized ionic liquid to deionized water in step 201 is 1:4; the volume ratio of the amino-functionalized ionic liquid to DMF in step 202 is 1:3; the mass concentration of the ethanol solution of the silane coupling agent KH-550 in step 303 is 3wt%, and the curing condition is immersion at 100°C for 2 hours; the ball mill is polished at a speed of 300 rpm, the ball milling medium is zirconia beads, and the polishing time is 15 minutes.

[0070] Example 2

[0071] This embodiment provides an aerogel@MOF composite material and a preparation method thereof;

[0072] The aerogel@MOF composite material is a composite of silica aerogel and a metal organic framework material, the metal organic framework material is a zirconium-based MOF material, and the zirconium-based MOF material is UiO-66.

[0073] The above-mentioned aerogel@MOF composite material, and its preparation method comprises the following steps:

[0074] Step 1: preparing silica aerogel, comprising the following steps:

[0075] Step 101: mixing ethyl orthosilicate, ethanol, and deionized water in a molar ratio of 1:3:3, adding hydrochloric acid to adjust the pH to 2, and stirring and hydrolyzing for 30 minutes to obtain a hydrolyzate;

[0076] Step 102: adding methyltrimethoxysilane to the hydrolyzate obtained in step 101, adjusting the pH to 5, and then allowing the mixture to stand for gelation to obtain a gel product; wherein the molar ratio of ethyl orthosilicate to methyltrimethoxysilane is 7:3;

[0077] Step 103: soaking the gel product obtained in step 102 in an ethanol solvent, and then drying it by supercritical CO2 to obtain the silica aerogel;

[0078] Step 2: In-situ synthesis of aerogel@MOF composite material, including the following steps:

[0079] Step 201, dissolving zirconium tetrachloride in an amino-functionalized ionic liquid in a mixed solvent of the amino-functionalized ionic liquid and deionized water to obtain a metal salt solution;

[0080] Step 202: dissolving terephthalic acid in a mixed solvent of an amino-functionalized ionic liquid and DMF to obtain a ligand solution;

[0081] Step 203: mixing the metal salt solution obtained in step 201 and the ligand solution obtained in step 202 at a volume ratio of 1:1 to obtain a mixed solution;

[0082] Step 204: adding the silica aerogel to the mixed solution obtained in step 203 to perform a hydrothermal reaction to obtain a composite material;

[0083] Step 3: post-processing and functionalizing the composite material obtained in step 204, including the following steps:

[0084] Step 301: collecting the composite material obtained in step 204 by centrifugation, washing it alternately with DMF and ethanol, and drying it to obtain a dry composite material;

[0085] Step 302: soaking the dried composite material obtained in step 301 in a NaOH solution to obtain an activated composite material;

[0086] Step 303: Immerse the activated composite material obtained in step 302 in an ethanol solution of silane coupling agent KH-550, and grind it in a ball mill after curing to obtain an aerogel@MOF composite material.

[0087] In the above preparation method, the volume ratio of the amino-functionalized ionic liquid to deionized water in step 201 is 1:4; the volume ratio of the amino-functionalized ionic liquid to DMF in step 202 is 1:3; the mass concentration of the ethanol solution of the silane coupling agent KH-550 in step 303 is 1 wt%, and the curing condition is immersion at 100°C for 0.5 hours; the ball mill is polished at a speed of 100 rpm, the ball milling medium is zirconia beads, and the polishing time is 5 minutes.

[0088] Example 3

[0089] This embodiment provides an additive and a preparation method thereof, wherein the additive is composed of the following components in percentage by weight: 25% aerogel@MOF composite material, 3% hydrogen peroxide, 3% polycarboxylate water reducer, 2% isobutyltriethoxysilane, 18% sodium metasilicate, 3% polypropylene fiber, 0.3% iron oxide catalyst, 0.7% citric acid, and 45% water.

[0090] The mass concentration of the hydrogen peroxide is 30%, the polycarboxylate water reducer is an alkali-resistant polycarboxylate water reducer, and the molecular weight of the polycarboxylate water reducer is 20,000 g / mol.

[0091] The polypropylene fiber is subjected to surface modification treatment, wherein the modifier in the surface modification is a silane coupling agent, and the length of the polypropylene fiber is 3 to 12 mm.

[0092] The preparation method of the above-mentioned additive comprises the following steps:

[0093] Step 1: pre-treating the additive component, comprising the following steps:

[0094] Step 101: soaking the polypropylene fiber in a 5% silane coupling agent KH-550 ethanol solution for 30 minutes, and then drying at 60° C. to obtain a modified polypropylene fiber;

[0095] Step 102: mixing the polycarboxylate water-reducing agent and silica fume in a mass ratio of 1:2, and spray-drying the mixture to prepare a polycarboxylate water-reducing agent powder having a particle size of 50 to 100 μm;

[0096] Step 103: pre-mixing the aerogel@MOF composite material and sodium metasilicate and grinding them to a particle size of 20 μm to obtain a ground dry material;

[0097] Step 104: premixing the hydrogen peroxide with citric acid and adjusting the pH to 4.5 to obtain stable hydrogen peroxide;

[0098] Step 2: Start the high-speed mixer and perform dry mixing, including the following steps:

[0099] Step 201: start the high-speed mixer, preheat it to 30° C., put the ground dry material and modified polypropylene fiber into the high-speed mixer, and mix for 20 minutes to obtain a premixed dry material;

[0100] Step 202: spray isobutyltriethoxysilane into the premixed dry material obtained in step 201, and mix for 15 minutes to obtain a completely mixed dry material;

[0101] Step 3: wet mixing the completely mixed dry materials in step 202, including the following steps:

[0102] Step 301: Heat 30% of water to 25° C., add polycarboxylate water reducer and stir until completely dissolved, inject into the high-speed mixer, and stir at a low speed of 500 rpm for 10 minutes to obtain a pre-wetted mixture;

[0103] Step 302: adding the stabilized hydrogen peroxide obtained in step 104 to the pre-moistened dry material obtained in step 301, and monitoring the temperature;

[0104] Step 303: When the temperature monitored in step 302 exceeds 30°C, add 30% water, increase the speed to 1200 rpm, and continue to monitor the temperature;

[0105] Step 304: When the temperature monitored in step 303 exceeds 30°C, add 30% water and continue stirring for 10 minutes;

[0106] Step 305: Add the iron oxide catalyst to the high-speed mixer, add the remaining water, and continue stirring to obtain the additive.

[0107] The inlet temperature of the spray drying in step 102 is 1180° C., the outlet temperature is 60° C., and the atomization pressure is 0.3 MPa.

[0108] Example 4

[0109] This embodiment provides an additive and a preparation method thereof, wherein the additive is composed of the following components in percentage by weight: 30% aerogel@MOF composite material, 3% hydrogen peroxide, 3% polycarboxylate water reducer, 1.5% isobutyltriethoxysilane, 10% sodium metasilicate, 1.5% polypropylene fiber, 0.4% iron oxide catalyst, 0.6% citric acid, and 50% water.

[0110] The mass concentration of the hydrogen peroxide is 30%, the polycarboxylate water reducer is an alkali-resistant polycarboxylate water reducer, and the molecular weight of the polycarboxylate water reducer is 20,000 g / mol.

[0111] The polypropylene fiber is subjected to surface modification treatment, wherein the modifier in the surface modification is a silane coupling agent, and the length of the polypropylene fiber is 3 to 12 mm.

[0112] The preparation method of the above-mentioned additive comprises the following steps:

[0113] Step 1: pre-treating the additive component, comprising the following steps:

[0114] Step 101: soaking the polypropylene fiber in a 5% silane coupling agent KH-550 ethanol solution for 30 minutes, and then drying at 60° C. to obtain a modified polypropylene fiber;

[0115] Step 102: mixing the polycarboxylate water-reducing agent and silica fume in a mass ratio of 1:2, and spray-drying the mixture to prepare a polycarboxylate water-reducing agent powder having a particle size of 50 to 100 μm;

[0116] Step 103: pre-mixing the aerogel@MOF composite material and sodium metasilicate and grinding them to a particle size of 20 μm to obtain a ground dry material;

[0117] Step 104: premixing the hydrogen peroxide with citric acid and adjusting the pH to 5.0 to obtain stable hydrogen peroxide;

[0118] Step 2: Start the high-speed mixer and perform dry mixing, including the following steps:

[0119] Step 201: start the high-speed mixer, preheat it to 30° C., put the ground dry material and modified polypropylene fiber into the high-speed mixer, and mix for 20 minutes to obtain a premixed dry material;

[0120] Step 202: spray isobutyltriethoxysilane into the premixed dry material obtained in step 201, and mix for 15 minutes to obtain a completely mixed dry material;

[0121] Step 3: wet mixing the completely mixed dry materials in step 202, including the following steps:

[0122] Step 301: Heat 30% of water to 25° C., add polycarboxylate water reducer and stir until completely dissolved, inject into the high-speed mixer, and stir at a low speed of 500 rpm for 10 minutes to obtain a pre-wetted mixture;

[0123] Step 302: adding the stabilized hydrogen peroxide obtained in step 104 to the pre-moistened dry material obtained in step 301, and monitoring the temperature;

[0124] Step 303: When the temperature monitored in step 302 exceeds 30°C, add 30% water, increase the speed to 1200 rpm, and continue to monitor the temperature;

[0125] Step 304: When the temperature monitored in step 303 exceeds 30°C, add 30% water and continue stirring for 10 minutes;

[0126] Step 305: Add the iron oxide catalyst to the high-speed mixer, add the remaining water, and continue stirring to obtain the additive.

[0127] The inlet temperature of the spray drying in step 102 is 150° C., the outlet temperature is 80° C., and the atomization pressure is ˜0.5 MPa.

[0128] Example 5

[0129] This example verifies the effects of additives prepared from the aerogel@MOF composite material provided by the present invention on the performance of AAC and ALC.

[0130] 1. Experimental design

[0131] AAC group: Aluminum powder (0.1%) was used as the gas-generating agent, and the basic formula was 30% cement, 60% quartz sand, 5% gypsum, and 5% additives.

[0132] ALC group: ceramsite (30% replacing quartz sand) is used as lightweight aggregate, and the basic formula is 30% cement, 30% ceramsite, 30% quartz sand, 5% gypsum, and 5% additives.

[0133] Additives: Additives prepared using aerogel@MIL-53(Al), aerogel@UiO-66 and blank aerogel (control group).

[0134] 2. Concrete preparation:

[0135] AAC: dry mix the raw materials → add water and stir (water-to-material ratio 0.6) → inject into the mold for gasification (pre-curing at 40℃ for 4h) → cut → autoclave curing (1.2MPa, 180℃, 8h).

[0136] ALC: dry mixing of raw materials → adding water and stirring (water-to-material ratio 0.5) → injection molding and vibration molding → autoclaving and curing (1.0 MPa, 170°C, 10 h).

[0137] 3. Performance test results:

[0138] Test standard: GB / T 11969-2020 "Test method for properties of autoclaved aerated concrete"

[0139] The test results of mechanical and physical properties are shown in Table 1.

[0140] Table 1: Effects of different types of additives on the performance of AAC and ALC

[0141]

[0142]

[0143] As shown in Table 1, the compressive strength of the AAC with the additive type of aerogel@MIL-53(Al) increased by 65.7%. 3+ It forms ≡Al-O-Si bonds with the silicate matrix and strengthens the pore wall structure.

[0144] The strength of ALC with aerogel@UiO-66 as the additive type increased by 55.8%, because the Zr-O bonds combined with the silanol groups on the surface of the ceramsite strengthened the aggregate-paste interface.

[0145] In terms of thermal conductivity, the aerogel@UiO-66 type additive makes the thermal conductivity of AAC as low as 0.09W / m · K, better than ALC group.

[0146] The durability comparison is shown in Table 2:

[0147] Table 2: Effects of different types of additives on the durability of AAC and ALC

[0148] Concrete type Additive type Water absorption rate (24h,%) <![CDATA[Chloride ion diffusion coefficient (×10 -12 m 2 / s)]]> AAC Blank aerogel 45±3 4.5±0.6 AAC Aerogel@MIL-53(Al) 28±2 1.2±0.2 AAC Aerogel@UiO-66 25±1 0.8±0.1 ALC Blank aerogel 38±2 3.8±0.4 ALC Aerogel@MIL-53(Al) 22±1 1.0±0.1 ALC Aerogel@UiO-66 18±1 0.6±0.05

[0149] As shown in Table 2, the addition of aerogel@UiO-66 additive in this embodiment further reduces the chloride ion diffusion coefficient of ALC to 0.6×10 -12 m 2 / s; it can be seen that the flexible pores of the aerogel@MIL-53(Al) provided by this invention shrink during autoclaving, squeezing the pore walls to densify the structure and enhance strength. The Zr6O4(OH)4 clusters in the aerogel@UiO-66 dehydrate and condense with the -Si-OH groups on the ceramic surface, forming Zr-O-Si covalent bonds, significantly improving interfacial bonding strength. The aerogel fills the macropores between the ceramic particles, while the MOF mesopores block the capillary water seepage pathway, significantly reducing water absorption.

[0150] Example 6

[0151] This example illustrates the effect of additives on concrete properties.

[0152] Control group: commercially available ordinary autoclaved aerated concrete (without the addition of aerogel@MOF composite);

[0153] Experimental group: aerogel@MIL-53(Al) additive prepared according to the formulation of Example 3;

[0154] Test standard: GB / T 11969-2020 "Test method for properties of autoclaved aerated concrete".

[0155] The test results are shown in Table 3:

[0156] Table 3: Effects of additives on concrete properties

[0157] Performance indicators control group Experimental group <![CDATA[Dry density (kg / m 3 )]]> 650±20 580±15 Compressive strength (MPa) 3.5±0.3 4.8±0.4 Thermal conductivity (W / m·K) 0.16±0.02 0.12±0.01 Water absorption rate (24h,%) 45±3 28±2

[0158] It can be seen that the nanopores of the aerogel@MOF composite material reduce the density of concrete and improve the thermal insulation performance; the interface bonding between the MOF skeleton and the silicate matrix enhances the mechanical properties; the functionalization of the silane coupling agent inhibits moisture penetration and significantly reduces the water absorption rate.

[0159] Example 7

[0160] This example is intended to illustrate the effects of adding MOF materials alone and silica aerogel alone on the quality of AAC building blocks.

[0161] This embodiment designs six experimental groups:

[0162] Blank control group: autoclaved aerated concrete prepared without additives;

[0163] MOF alone group: autoclaved aerated concrete prepared with 5% of pure MIL-53(Al) additive;

[0164] Aerogel group: autoclaved aerated concrete prepared by adding 5% of pure silica aerogel additive;

[0165] Physical mixing group: autoclaved aerated concrete prepared by adding 2.5% of MOF and 2.5% of aerogel (not in situ compounded) additives;

[0166] Composite material group: autoclaved aerated concrete prepared by adding 5% of the aerogel@MIL-53(Al) additive described in Example 1;

[0167] Commercially available AAC group: Commercially available autoclaved aerated concrete (density 650kg / m 3 , compressive strength 3.5MPa).

[0168] According to the AAC standard formula (cement 30%, quartz sand 60%, gypsum 5%, additives 5%), the water-to-material ratio was 0.6, and the above six experimental groups of additives were used to prepare AAC blocks. The 28-day compressive strength, chloride ion diffusion coefficient and other indicators were measured according to the national standard. The test results are shown in the following table:

[0169] Table 4: Effects of individual material additives on the comprehensive properties of AAC blocks

[0170]

[0171] The data in Table 4 show that the composite material group exhibits significant advantages in the application of autoclaved aerated concrete: its compressive strength reaches 5.6±0.4MPa, which is 47% higher than that of the blank control group and higher than that of the group with MOF or aerogel added alone, indicating that the in-situ composite of silica aerogel and MOF produces a synergistic enhancement effect; the chloride ion diffusion coefficient is as low as 1.2×10 -12 m 2 / s, which is 71% lower than that of the blank group. This is due to the high specific surface area of ​​MOF that adsorbs and locks corrosive ions, and the aerogel nanopores that block the permeation path. The dry density of the composite material group is 560±8kg / m 3 This is primarily due to the dual weight-reduction effects of the aerogel's low-density skeleton and the MOF's mesoporous structure. Furthermore, the composite material is reinforced through interfacial bonding by the silane coupling agent KH-550, ultimately reducing the required autoclave pressure to 0.8 MPa, a 38% reduction compared to the commercially available AAC. The performance gap between the physical mixing group and the composite material group reveals that the in-situ hydrothermal synthesis process chemically bonds the MOF within the aerogel's pores, avoiding the interfacial defects associated with simple physical mixing, thereby more effectively improving the durability and mechanical properties of concrete.

[0172] Example 8

[0173] This example is intended to illustrate the role of aerogel@MOF composites treated with amino-functionalized ionic liquids in the production of ACC and ALC.

[0174] 1. Experimental design

[0175] This embodiment designs four experimental groups:

[0176] Group 1: AAC prepared by adding additives to aerogel@MIL-53(Al) treated with amino-functionalized ionic liquid;

[0177] Group 2: AAC produced by aerogel@MIL-53(Al) without the additives treated with amino-functionalized ionic liquid;

[0178] Group 3: ALC prepared by adding additives to aerogel@MIL-53(Al) treated with amino-functionalized ionic liquid;

[0179] Group 4: ALC produced by preparing aerogel@MIL-53(Al) without amino-functionalized ionic liquid treatment.

[0180] The preparation process and conditions of the concrete are the same as those in Example 5.

[0181] 2. Performance test results:

[0182] The data table for the impact of AAC performance is shown in Table 5:

[0183] Table 5: AAC performance comparison

[0184]

[0185]

[0186] The data table for the impact of ALC performance is shown in Table 6:

[0187] Table 6: ALC performance comparison

[0188] index Group 4 Group 3 Compressive strength (MPa) 6.0±0.4 7.5±0.5 <![CDATA[Fracture energy (J / m 2 )]]> 55±4 65±4 Water absorption rate (24h,%) 22±1 18±1

[0189] As can be seen from Tables 5 and 6, the present invention significantly improves the compressive strength, thermal insulation, and durability of autoclaved aerated concrete (AAC) and autoclaved lightweight concrete (ALC) by strengthening the interfacial bonding and hierarchical pore structure of the aerogel@MOF composite material by using amino-functionalized ionic liquid (NH2-IL) and combining the chemical stability and functional adjustability of aluminum-based (MIL-53(Al)) and zirconium-based (UiO-66) MOFs.

[0190] Example 9

[0191] This example compares the performance differences of MOF composite materials prepared by zinc-based (ZIF-8), copper-based (HKUST-1), and chromium-based (MIL-101 (Cr)) and the preferred aluminum-based (MIL-53 (Al)) and zirconium-based (UiO-66) MOF composite materials of the present invention as additives in AAC and ALC to verify the superiority of the MOF selection of the present invention.

[0192] 1. Experimental Design

[0193] Preparation of aerogel@MOF composite materials:

[0194] Aerogel@ZIF-8: The aerogel was immersed in a methanol solution of zinc nitrate (0.1 M) and 2-methylimidazole (0.4 M) and reacted at room temperature for 24 h.

[0195] Aerogel@HKUST-1: Aerogel, copper nitrate (0.05 M), and trimesic acid (0.03 M) were hydrothermaled in DMF at 80 °C for 12 h.

[0196] Aerogel@MIL-101(Cr): Aerogel was hydrothermally treated with Cr(NO3)3·9H2O (0.02 M), terephthalic acid (0.01 M), and HF (0.05 M) at 220 °C for 48 h.

[0197] Aerogel@MIL-53(Al): prepared according to the method of Example 1.

[0198] Aerogel@UiO-66: The method in Example 1 was replaced with ZrCl4 and terephthalic acid, and hydroheated at 120°C for 24 h.

[0199] All groups were ball milled, and the concrete preparation process and conditions were the same as in Example 5.

[0200] 2. Performance test results:

[0201] Test standard: GB / T 11969-2020 "Test method for properties of autoclaved aerated concrete"; its performance impact on AAC is shown in Table 7:

[0202] Table 7: Effects of different types of additives on the performance of AAC

[0203]

[0204] As can be seen from Table 7, MIL-53(Al) has the best strength in AAC: the compressive strength is 6.85 MPa, which is far higher than that of other MOF groups. This is because Al3+ forms ≡Al-O-Si bonds with silicates, which strengthens the pore wall structure.

[0205] Zirconium-based MOF (UiO-66) has the best durability in AAC: the chloride ion diffusion coefficient is as low as 0.8×10-12m2 / s, because the Zr-O bond is more alkali-resistant.

[0206] Table 8 provides a statistical description of the effects of different types of additives on ALC:

[0207] Table 8: Effects of different types of additives on the performance of ALC

[0208] Additive type Compressive strength (MPa) <![CDATA[Fracture energy (J / m 2 )]]> Water absorption rate (24h,%) Aerogel@ZIF-8 6.0±0.4 55±4 25±2 Aerogel@HKUST-1 5.5±0.3 50±3 28±3 Aerogel@MIL-101(Cr) 7.2±0.5 60±5 20±1 MIL-53(Al)@aerogel 7.5±0.5 65±4 18±1 Aerogel@UiO-66 8.1±0.6 68±4 18±1

[0209] As shown in Table 8, the ALC prepared with zirconium-based MOF (UiO-66) as the additive type has the best comprehensive performance: compressive strength 8.1MPa, fracture energy 68J / m 2 The Zr-O bond condenses with the silanol group (-Si-OH) on the surface of the ceramsite, and the interface bonding strength is increased by 40%; the additive type is ALC prepared by chromium-based MOF (MIL-101 (Cr)) or due to Cr 3+ Partially dissolves in alkaline environment, weakening the structural stability. The additive type is ALC prepared by ZIF-8, Zn 2+ Poor compatibility with silicate and easy interface peeling resulted in a strength of only 3.2 MPa, which was only 47% of that of the aluminum-based group. 2+ In alkaline environment, CuO is oxidized to form, which destroys the MOF structure and has poor structural stability. ALC prepared with MIL-101(Cr) additive has high specific surface area, but Cr 3+ Toxicity and cost limit industrial application.

[0210] In summary, the present invention preferably uses aerogel@composite materials prepared from aluminum-based (MIL-53(Al)) and zirconium-based (UiO-66) MOFs. Through chemical bonding interface strengthening, hierarchical pore structure optimization, and functional integration design, it achieves improved compressive strength and durability indicators in AAC and ALC that are superior to traditional and other MOF systems. At the same time, it reduces the overall cost and promotes the upgrading of the concrete industry towards high performance, low energy consumption, and green development.

[0211] As described above, the basic principles, main features and advantages of the present invention are well described. The above embodiments and descriptions are merely descriptions of preferred embodiments of the present invention, and the present invention is not limited to the above embodiments. Various changes and improvements made to the technical solutions of the present invention by those skilled in the art without departing from the spirit and scope of the present invention should fall within the scope of protection determined by the present invention.

Claims

1. A method for preparing an aerogel@MOF composite material, characterized in that: The aerogel@MOF composite material is a composite of silica aerogel and a metal organic framework material, and the metal organic framework material is an aluminum-based MOF material or a zirconium-based MOF material; The aluminum-based MOF material is MIL-53 (Al) or CAU-10-H; the zirconium-based MOF material is UiO-66 or UiO-67; The preparation method comprises the following steps: Step 1: preparing silica aerogel, comprising the following steps: Step 101: mixing ethyl orthosilicate, ethanol, and deionized water in a molar ratio of 1:(3-5):(3-5), adding hydrochloric acid to adjust the pH to 2-3, and stirring and hydrolyzing for 30 minutes to obtain a hydrolyzate; Step 102: adding methyltrimethoxysilane to the hydrolyzate obtained in step 101, adjusting the pH to 5-6, and then allowing the mixture to stand for gelation to obtain a gel product; wherein the molar ratio of the ethyl orthosilicate to methyltrimethoxysilane is 3:2-7:3; Step 103: soaking the gel product obtained in step 102 in an ethanol solvent, and then drying it by supercritical CO2 to obtain a silica aerogel; Step 2: In-situ synthesis of aerogel@MOF composite material, including the following steps: Step 201: dissolving a metal salt in a mixed solvent of an amino-functionalized ionic liquid and deionized water to obtain a metal salt solution; Step 202: dissolving the organic ligand in a mixed solvent of an amino-functionalized ionic liquid and DMF to obtain a ligand solution; Step 203: mixing the metal salt solution obtained in step 201 and the ligand solution obtained in step 202 at a volume ratio of 1:1 to obtain a mixed solution; Step 204: adding the silica aerogel to the mixed solution obtained in step 203 to perform a hydrothermal reaction to obtain a composite material; Step 3: post-processing and functionalizing the composite material obtained in step 204, including the following steps: Step 301: collecting the composite material obtained in step 204 by centrifugation, washing it alternately with DMF and ethanol, and drying it to obtain a dry composite material; Step 302: soaking the dried composite material obtained in step 301 in a NaOH solution to obtain an activated composite material; Step 303: Immerse the activated composite material obtained in step 302 in an ethanol solution of silane coupling agent KH-550, and grind it in a ball mill after curing to obtain an aerogel@MOF composite material.

2. The preparation method according to claim 1, characterized in that The volume ratio of the amino-functionalized ionic liquid to deionized water in step 201 is 1:4; the volume ratio of the amino-functionalized ionic liquid to DMF in step 202 is 1:3; the mass concentration of the ethanol solution of the silane coupling agent KH-550 in step 303 is 1-3wt%, and the curing conditions are immersion at 60-100°C for 0.5-2 hours; the ball mill is polished at a speed of 100-300 rpm, the ball milling medium is zirconia beads, and the polishing time is 5-15 minutes.

3. Use of the aerogel@MOF composite material prepared by the preparation method according to claim 1 or 2 in the preparation of an autoclaved lightweight concrete additive.

4. The use according to claim 3, characterized in that The additive consists of the following components in percentage by weight: 25-30% aerogel@MOF composite material, 3-5% hydrogen peroxide, 3-5% polycarboxylic acid water reducer, 1.5-2% isobutyltriethoxysilane, 10-20% sodium metasilicate, 1.5-3% polypropylene fiber, 0.3-0.45% iron oxide catalyst, 0.6-1% citric acid, and 45-55% water.

5. The use according to claim 4, characterized in that The mass concentration of the hydrogen peroxide is 30%; the polycarboxylate water reducer is an alkali-resistant polycarboxylate water reducer, and the molecular weight of the polycarboxylate water reducer is 5000-20000 g / mol.

6. The use according to claim 4, characterized in that The polypropylene fiber is subjected to surface modification treatment, wherein the modifier in the surface modification is a silane coupling agent or a titanate coupling agent, and the length of the polypropylene fiber is 3 to 12 mm.

7. The use according to any one of claims 4 to 6, characterized in that The preparation method of the additive comprises the following steps: Step 1: pre-treating the additive component, comprising the following steps: Step 101: soaking the polypropylene fiber in a 5% silane coupling agent KH-550 ethanol solution for 30 minutes, and then drying at 60° C. to obtain a modified polypropylene fiber; Step 102: mixing the polycarboxylate water-reducing agent and silica fume in a mass ratio of 1:2, and spray-drying the mixture to prepare a polycarboxylate water-reducing agent powder having a particle size of 50 to 100 μm; Step 103: pre-mixing the aerogel@MOF composite material and sodium metasilicate and grinding them to a particle size of 20 μm to obtain a ground dry material; Step 104: premixing the hydrogen peroxide with citric acid, adjusting the pH to 4.5-5.0, and obtaining stable hydrogen peroxide; Step 2: Start the high-speed mixer and perform dry mixing, including the following steps: Step 201: start the high-speed mixer, preheat it to 30° C., put the ground dry material and modified polypropylene fiber into the high-speed mixer, and mix for 20 minutes to obtain a premixed dry material; Step 202: spray isobutyltriethoxysilane into the premixed dry material obtained in step 201, and mix for 15 minutes to obtain a completely mixed dry material; Step 3: wet mixing the completely mixed dry materials in step 202, including the following steps: Step 301: Heat 30% of water to 25° C., add the polycarboxylate water-reducing agent powder and stir until completely dissolved, inject into the high-speed mixer, and stir at a low speed of 500 rpm for 10 minutes to obtain a pre-wetted mixture; Step 302: adding the stabilized hydrogen peroxide obtained in step 104 to the pre-wetted mixture obtained in step 301, and monitoring the temperature; Step 303: When the temperature monitored in step 302 exceeds 30°C, add 30% water, increase the speed to 1200 rpm, and continue to monitor the temperature; Step 304: When the temperature monitored in step 303 exceeds 30°C, add 30% water and continue stirring for 10 minutes; Step 305: Add the iron oxide catalyst to the high-speed mixer, add the remaining water, and continue stirring to obtain the additive.

8. The use according to claim 7, characterized in that The inlet temperature of the spray drying in step 102 is 150-180° C., the outlet temperature is 60-80° C., and the atomization pressure is 0.3-0.5 MPa.

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