Preparation method of MOFs-based composite phase change material

Abstract

The invention discloses a preparation method of an MOFs (Metal-Organic Frameworks)-based composite phase change material, which comprises the following steps: (1) mixing soluble metal salt, an organic ligand and a solvent, then carrying out synthetic reaction, washing, separating and drying a hydrothermal product, and then carrying out activating treatment to obtain an MOFs carrier with unsaturated metal sites; (2) adding the MOFs carrier with the unsaturated metal sites obtained in the step (1) into a solution containing a soluble phase change material, dipping for a period of time, then adding a silane coupling agent, continuously reacting for a period of time, and then drying to obtain a composite phase change material precursor; and (3) carrying out condensation polymerization on the composite phase change material precursor and a silicon dioxide precursor in formamide, and filtering and drying a reaction product to obtain the MOFs-based composite phase change material. The composite phase change material prepared by the method has excellent permeability resistance, heat storage density and heat stability, and has a good application prospect.

Description

Technical Field

[0001] The invention belongs to the technical field of phase change materials, and in particular relates to a method for preparing a MOFs-based composite phase change material with excellent anti-permeability. Background Art

[0002] Phase change materials (PCMs) are functional materials that use the latent heat of phase change to achieve heat storage and utilization. These materials have been widely used in the fields of construction, textiles, electronics, medical treatment, solar energy, etc. Among them, solid-liquid phase change materials have attracted the attention of many researchers due to their wide variety, adjustable phase change temperature, and high latent heat. However, liquid leakage of solid-liquid phase change materials has always been a problem of concern.

[0003] In order to solve the problem of easy leakage of phase change materials, researchers use porous carriers to adsorb phase change materials. Common carriers include expanded graphite, bentonite, carbon nanotubes, aerogels, metal organic frameworks (MOFs), etc. Among them, MOFs have attracted more and more attention as adsorption carriers of phase change materials due to their large specific surface area, adjustable pore size and pore volume. CN 111187596 B discloses a metal-organic framework composite phase change material for thermal energy management system and a preparation method thereof. The method synthesizes a modified metal organic framework carrier by functional modification and synthesis of 1,3,5-benzenetriyl chloride as a ligand, and further obtains a composite phase change material with a higher loading amount by regulating the pore chemical properties of the metal organic framework. CN 108624295 B discloses a method for preparing a porous carbon-based electrothermal composite phase change material. The method uses a core-shell structure MOFs@MOFs as a template, prepares a three-dimensional carbon nanotube porous carbon carrier by a one-step calcination method, and then prepares a composite phase change material, which effectively improves the electrical conductivity and thermal conductivity of the material and has a high electrothermal conversion efficiency. CN104745149B discloses a method for preparing a carbon-containing metal organic framework-based composite phase change material. The method uses hydrothermal growth of MOFs particles as a carrier on a carbon material, and further prepares a composite phase change material by vacuum adsorption, which improves heat transfer performance and anti-permeability.

[0004] However, the pore structure of MOFs is mainly open interconnected micropores or mesopores, which only rely on weak capillary forces, surface tension and hydrogen bonds to adsorb phase change materials. Composite phase change materials based on MOFs have the risk of leakage during multiple heat absorption and heat release processes. Therefore, how to improve the anti-permeability performance of MOFs-based composite phase change materials is an important issue that needs to be solved at present. Summary of the invention

[0005] In view of the shortcomings of the prior art, the present invention provides a method for preparing a MOFs-based composite phase change material. The composite phase change material prepared by the method of the present invention has excellent anti-permeability, heat storage density and thermal stability, and has good application prospects.

[0006] The preparation method of the MOFs-based composite phase change material of the present invention comprises the following contents:

[0007] (1) A soluble metal salt, an organic ligand and a solvent are mixed, and then a synthesis reaction is carried out. The product after hydrothermal treatment is washed, separated, dried, and then activated to obtain a MOFs carrier with unsaturated metal sites;

[0008] (2) adding the MOFs support having unsaturated metal sites obtained in step (1) into a solution containing a soluble phase change material and immersing it for a period of time, then adding a silane coupling agent and continuing the reaction for a period of time, and then drying to obtain a composite phase change material precursor;

[0009] (3) The composite phase change material precursor and the silica precursor are subjected to a condensation reaction in formamide, and the reaction product is filtered and dried to obtain a MOFs-based composite phase change material.

[0010] In the method of the present invention, the soluble metal salt in step (1) is selected from one or more of chromium nitrate, ferric nitrate, ferric chloride, copper nitrate and zirconium chloride.

[0011] In the method of the present invention, the organic ligand described in step (1) is selected from one or more of terephthalic acid, 2-aminoterephthalic acid, trimesic acid and dicarboxylic acid terphenyl.

[0012] In the method of the present invention, the solvents in step (1) and step (2) are selected from one or more of water, N,N-dimethylformamide, anhydrous ethanol, methanol, dimethyl sulfoxide, n-hexane and n-pentane.

[0013] In the method of the present invention, the mass ratio of the soluble metal salt, the organic ligand and the solvent in step (1) is (4.1-1.5):1:(33.3-117.6).

[0014] In the method of the present invention, the reaction conditions of step (1) are: reaction at 30-180° C. for 5-24 hours, and the reaction is generally carried out under stirring conditions.

[0015] In the method of the present invention, the washing and separation process described in step (1) is well known to those skilled in the art, and is generally washed with N,N-dimethylformamide and anhydrous ethanol respectively, and then centrifugal separation or the like can be used.

[0016] In the method of the present invention, the drying conditions in step (1) are: a drying temperature of 80 to 120° C. and a drying time of 4 to 24 hours, generally carried out in an air atmosphere, such as using a blast drying oven.

[0017] In the method of the present invention, the activation treatment method described in step (1) can be vacuum drying, chemical activation, photothermal activation, etc., such as vacuum drying conditions: vacuum drying at 120-150° C. for 8-24 hours.

[0018] In the method of the present invention, the soluble phase change material described in step (2) is selected from one or more of stearic acid, lauric acid, palmitic acid, octadecyl alcohol, polyethylene glycol 2000, polyethylene glycol 4000, polyethylene glycol 6000, 52# paraffin, 28# paraffin, n-hexadecane, n-octadecane and n-docosane.

[0019] In the method of the present invention, the solvent used in the solution containing the soluble phase change material in step (2) is selected from one or more of water, N,N-dimethylformamide, anhydrous ethanol, methanol, dimethyl sulfoxide, n-hexane, and n-pentane; the concentration of the solution is 0.01 g / mL to 0.5 g / mL.

[0020] In the method of the present invention, the mass ratio of the MOFs carrier to the soluble phase change material in step (2) is 1-1:4-1.

[0021] In the method of the present invention, the immersion time in step (2) is 1 to 4 hours.

[0022] In the method of the present invention, the silane coupling agent described in step (2) is one or more of mercaptopropyltriethoxysilane, mercaptopropyltriethoxysilane, aminopropyltriethoxysilane, and aminopropyltrimethoxysilane.

[0023] In the method of the present invention, the reaction time after adding the silane coupling agent in step (2) is 3 to 5 hours.

[0024] In the method of the present invention, the drying conditions in step (2) are: drying time is 4 to 20 hours, and drying temperature is 80 to 100°C.

[0025] In the method of the present invention, the silicon dioxide precursor described in step (3) is selected from one or more of tetraethyl orthosilicate, methyltriethoxysilane, propyltriethoxysilane and octyltriethoxysilane.

[0026] In the method of the present invention, the mass ratio of the composite phase change material precursor to the silicon dioxide precursor in step (3) is 1-1:3-1.

[0027] In the method of the present invention, the polycondensation reaction conditions in step (3) are as follows: the reaction time is 1 to 7 days, the pH value is 2.5 to 4, the reaction temperature is at room temperature, and the reaction is generally carried out under stirring conditions.

[0028] The present invention uses a metal-organic framework material composed of a secondary structure containing metal clusters and organic ligands. By removing coordinated water molecules through high-temperature vacuum drying, a large number of unsaturated metal sites can be exposed on the MOFs, and further coordinated with electron-rich groups. In the present invention, coordinated water molecules in the MOFs are removed through activation treatment to expose unsaturated metal sites, and then a phase change material (PCM) is loaded by a solvent adsorption method to form PCM@MOFs. Then, the unsaturated metal sites in the MOFs are coordinated with a silane coupling agent to obtain a composite phase change material precursor. Finally, a layer of silica is formed on the surface of PCM@MOFs by the co-condensation of the silane coupling agent and tetraethyl orthosilicate (TEOS), obtaining a composite phase change material with excellent thermal stability and anti-permeability. By coordinating with unsaturated metal sites and electron-rich groups, the window pore size is effectively reduced, and silica is formed through hydrolysis polycondensation.

[0029] The beneficial effects of the present invention are as follows:

[0030] (1) By coordinating the unsaturated metal sites in the MOFs with a silane coupling agent, the anti-permeability of the composite phase change material is significantly improved. The melting permeability of the prepared PCM@MOFs@(Me)-S-Si@SiO 2 at (75 °C, 360 min) is only 0.69% - 2.97%, which is reduced by 5.78% - 38.81% compared with PCM@MOFs.

[0031] (2) The PCM@MOFs@(Me)-S-Si@SiO prepared by the present invention 2 has good heat storage density. The melting enthalpy of the sample can reach 60.3 - 118.3 J / g, and the crystallization enthalpy can reach 59.5 - 118.5 J / g.

[0032] (3) The PCM@MOFs@(Me)-S-Si@SiO prepared by the present invention 2 has good thermal stability. After the sample is dried in a blast oven at 75 °C for 7 days, the heat storage performance only decreases by 0.17%. Brief Description of the Drawings

[0033] Figure 1 is the DSC melting diagram of PCM@MOFs@(Me)-S-Si@SiO described in Examples 1 - 3 of the present invention 2 of.

[0034] Figure 2PCM@MOFs@(Me)-S-Si@SiO described in Examples 1 to 3 of the present invention 2 DSC crystallization diagram of .

[0035] Figure 3 PCM@MOFs@(Me)-S-Si@SiO described in Examples 1 to 3 of the present invention 2 Melt permeability test diagram.

[0036] Figure 4 PCM@MOFs@(Me)-S-Si@SiO described in Example 1 of the present invention 2 DSC analysis diagram before and after 7 days in 75℃ oven. DETAILED DESCRIPTION

[0037] It should be noted that the following detailed descriptions are exemplary and are intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs.

[0038] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0039] The present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments:

[0040] Example 1

[0041] MIL-101(Cr)-NH 2 As carrier; stearic acid as phase change material, the dosage is MIL-101(Cr)-NH 2 233.3%; TEOS is used as SA@MIL-101(Cr)-NH 2 @(Cr)-S-Si 50% as an example.

[0042] 1.44 g of 2-aminoterephthalic acid, 3.2 g of chromium nitrate nonahydrate and 0.8 g of sodium hydroxide were dissolved in 60 mL of N, N-dimethylformamide and stirred at 25 ° C for 30 min. The solution was then transferred to a reactor and hydrothermally reacted at 150 ° C for 12 h. The solid was collected by centrifugation and washed three times with N, N-dimethylformamide and anhydrous ethanol respectively. The solid was dried in a forced air drying oven at 80 ° C for 12 h and then vacuum dried at 120 ° C for 12 h to obtain MIL-101(Cr)-NH with unsaturated metal sites. 2 carrier.

[0043] 1.89 g of stearic acid was dissolved in 30 mL of 90 °C hot n-hexane by magnetic stirring. After 30 min, 0.81 g of MIL-101(Cr)-NH 2 Add to the solution and react for 4 h, then add 0.3 g of KH590 to the solution and react for 5 h to obtain SA@MIL-101(Cr)-NH 2 @(Cr)-S-Si composite phase change material.

[0044] Take 3.0g of SA@MIL-101(Cr)-NH 2 @(Cr)-S-Si and 1.5 g of TEOS were added to 40 mL of formamide solution and dispersed under magnetic stirring for 30 min. Then, 0.1 mol / L HCl solution was added dropwise to adjust the pH of the system to 3.5. The system was magnetically stirred at 25 °C for 7 days. The solid was collected by filtration and then washed three times with deionized water to obtain SA@MIL-101(Cr)-NH 2 @(Cr)-S-Si@SiO 2 Composite phase change materials.

[0045] The results show that if Figure 1 , 2 As shown, SA@MIL-101(Cr)-NH 2 @(Cr)-S-Si@SiO 2 The melting enthalpy of can reach 118.3 J / g. Figure 3 As shown, SA@MIL-101(Cr)-NH 2 @(Cr)-S-Si@SiO 2 The melt permeability of SA@MIL-101(Cr)-NH 2 It decreased by 8.06%. Figure 4 As shown, after the sample was placed in an oven at 75°C for 7 days, the melting enthalpy decreased by only 0.21 J / g.

[0046] Example 2

[0047] MIL-101(Cr)-NH2 As carrier; stearic acid as phase change material, the dosage is MIL-101(Cr)-NH 2 233.3%; based on the TEOS mass, SA@MIL-101(Cr)-NH 2 Take 33.3% of @(Cr)-S-Si as an example.

[0048] MIL-101(Cr)-NH with unsaturated metal sites 2 The preparation method of the carrier is the same as that in Example 1.

[0049] SA@MIL-101(Cr)-NH 2 The preparation method of @(Cr)-S-Si is the same as that in Example 1.

[0050] Take 3.0g of SA@MIL-101(Cr)-NH 2 @(Cr)-S-Si and 1.0 g of TEOS were added to 40 mL of formamide solution and dispersed under magnetic stirring for 30 min. Then, 0.1 mol / L HCl solution was added dropwise to adjust the pH of the system to 3.5. The system was magnetically stirred at 25 °C for 7 days and washed with deionized water and filtered to obtain SA@MIL-101(Cr)-NH 2 @(Cr)-S-Si@SiO 2 Composite phase change materials.

[0051] The results show that if Figure 1 , 2 As shown, SA@MIL-101(Cr)-NH 2 @(Cr)-S-Si@SiO 2 The melting enthalpy of can reach 107.2J. Figure 3 As shown, SA@MIL-101(Cr)-NH 2 @(Cr)-S-Si@SiO 2 The melt permeability of SA@MIL-101(Cr)-NH 2 A decrease of 6.94%.

[0052] Example 3

[0053] MIL-101(Cr)-NH 2 As carrier; stearic acid as phase change material, the dosage is MIL-101(Cr)-NH 2 233.3%; based on the TEOS mass, SA@MIL-101(Cr)-NH 2 @(Cr)-S-Si 100% as an example.

[0054] MIL-101(Cr)-NH with unsaturated metal sites 2 The preparation method of the carrier is the same as that in Example 1.

[0055] SA@MIL-101(Cr)-NH 2 The preparation method of @(Cr)-S-Si is the same as that in Example 1.

[0056] Take 3.0g of SA@MIL-101(Cr)-NH 2 @(Cr)-S-Si and 3.0 g of TEOS were added to 40 mL of formamide solution and dispersed under magnetic stirring for 30 min. Then, 0.1 mol / L HCl solution was added dropwise to adjust the pH of the system to 3.5. The system was magnetically stirred at 25 °C for 7 days and washed with deionized water and filtered to obtain SA@MIL-101(Cr)-NH 2 @(Cr)-S-Si@SiO 2 Composite phase change materials.

[0057] The results show that if Figure 1 , 2 As shown, SA@MIL-101(Cr)-NH 2 @(Cr)-S-Si@SiO 2 The melting enthalpy of can reach 79.3J / g. Figure 3 As shown, SA@MIL-101(Cr)-NH 2 @(Cr)-S-Si@SiO 2 The melt permeability of SA@MIL-101(Cr)-NH 2 A decrease of 5.78%.

[0058] Example 4

[0059] MIL-101(Cr)-NH 2 As carrier; polyethylene glycol 6000 (PEG) as phase change material, the dosage is MIL-101(Cr)-NH 2 150% of TEOS quality; SA@MIL-101(Cr)-NH 2 @(Cr)-S-Si 50% as an example.

[0060] MIL-101(Cr)-NH with unsaturated metal sites 2 The preparation method of the carrier is the same as that in Example 1.

[0061] 1.62 g of polyethylene glycol 6000 was dissolved in 30 mL of anhydrous ethanol at 90 °C with magnetic stirring. After 30 min, 1.08 g of MIL-101(Cr)-NH 2Add to the solution and react for 4 h, then add 0.3 g of KH590 to the solution and react for 5 h to obtain PEG@MIL-101(Cr)-NH 2 @(Cr)-S-Si composite phase change material.

[0062] Take 3.0g of PEG@MIL-101(Cr)-NH 2 @(Cr)-S-Si and 1.5 g of TEOS were added to 40 mL of formamide solution and dispersed under magnetic stirring for 30 min. Then, 0.1 mol / L HCl solution was added dropwise to adjust the pH of the system to 3.5. The system was magnetically stirred at 25 °C for 7 days and washed with anhydrous ethanol and filtered to obtain PEG@MIL-101(Cr)-NH 2 @(Cr)-S-Si@SiO 2 Composite phase change materials.

[0063] The results showed that PEG@MIL-101(Cr)-NH 2 @(Cr)-S-Si@SiO 2 The melting enthalpy of PEG@MIL-101(Cr)-NH 2 @(Cr)-S-Si@SiO 2 The melt permeability of PEG@MIL-101(Cr)-NH 2 Reduced by 5.75%.

[0064] Example 5

[0065] MIL-101(Cr)-NH 2 as carrier; 52# paraffin wax (PW) as phase change material, with the dosage of MIL-101(Cr)-NH 2 100%; TEOS quality is PW@MIL-101(Cr)-NH 2 @(Cr)-S-Si 50% as an example.

[0066] 1.35 g of 52# paraffin wax was dissolved in 30 mL of 90°C hot n-hexane by magnetic stirring. After 30 min, 1.35 g of MIL-101(Cr)-NH 2 Add to the solution and react for 4 h, then add 0.3 g of KH590 to the solution and react for 5 h to obtain PW@MIL-101(Cr)-NH 2 @(Cr)-S-Si composite phase change material.

[0067] Take 3.0g of PW@MIL-101(Cr)-NH 2@(Cr)-S-Si and 1.5 g of TEOS were added to 40 mL of formamide solution and dispersed under magnetic stirring for 30 min. Then, 0.1 mol / L HCl solution was added dropwise to adjust the pH of the system to 3.5. The system was magnetically stirred at 25 °C for 7 days and washed with anhydrous ethanol and filtered to obtain PW@MIL-101(Cr)-NH 2 @(Cr)-S-Si@SiO 2 Composite phase change materials.

[0068] The results show that PW@MIL-101(Cr)-NH 2 @(Cr)-S-Si@SiO 2 The melting enthalpy of PW@MIL-101(Cr)-NH 2 @(Cr)-S-Si@SiO 2 The melt permeability of PEG@MIL-101(Cr)-NH 2 A decrease of 3.14%.

[0069] Example 6

[0070] Take HKUST-1 as the carrier; stearic acid as the phase change material, with the dosage being 150% of HKUST-1; and TEOS with a mass of 50% of SA@HKUST-1@(Cu)-S-Si as an example.

[0071] 0.882 g of trimesic acid and 1.812 g of copper nitrate trihydrate were dissolved in 50 mL of methanol under magnetic stirring at room temperature for 5 min, and the two solutions were mixed and allowed to stand at room temperature for 2 h to obtain a sky blue precipitate. The HKUST-1 carrier with unsaturated metal sites was obtained by washing with methanol, centrifugal drying, forced air drying at 50 ° C for 12 h, and vacuum drying at 100 ° C for 12 h.

[0072] 1.62 g of stearic acid was dissolved in 30 mL of 90 °C hot n-hexane with magnetic stirring. After 30 min, 1.08 g of HKUST-1 was added to the solution and reacted for 4 h. 0.3 g of KH590 was added to the solution and reacted for 5 h to obtain the SA@HKUST-1@(Cu)-S-Si composite phase change material.

[0073] 3.0 g of SA@HKUST-1@(Cu)-S-Si and 1.5 g of TEOS were added to 40 mL of formamide solution and dispersed under magnetic stirring for 30 min. Then, 0.1 mol / L HCl solution was added dropwise to adjust the pH of the system to 3.5. The system was magnetically stirred at 25 °C for 7 days and washed with anhydrous ethanol and filtered to obtain SA@HKUST-1@(Cu)-S-Si@SiO 2 Composite phase change materials.

[0074] The results show that SA@HKUST-1@(Cu)-S-Si@SiO 2 The melting enthalpy of SA@HKUST-1@(Cu)-S-Si@SiO 2 The melt permeability can reach 0.79%, which is 24.04% lower than that of SA@HKUST-1.

[0075] Example 7

[0076] Take UiO-68 as the carrier; stearic acid as the phase change material, the dosage is 150% of UiO-68; take TEOS mass as 50% of SA@UiO-68@(Cu)-S-Si as an example.

[0077] 0.12g of dicarboxylic acid terphenyl and 0.098g of zirconium chloride were dissolved in 60mL of N, N-dimethylformamide under stirring at 25°C for 30min, and then 1.15mL of trifluoroacetic acid was added. The solution was transferred to a reactor for hydrothermal reaction at 120°C for 72h, and washed and centrifuged with N, N-dimethylformamide and anhydrous ethanol respectively. After air drying at 80°C for 12h and vacuum drying at 120°C for 12h, the UiO-68 carrier with unsaturated metal sites was obtained.

[0078] 1.62 g of stearic acid was dissolved in 30 mL of 90 °C hot n-hexane with magnetic stirring. After 30 min, 1.08 g of UiO-68 was added to the solution and reacted for 4 h. 0.3 g of KH590 was added to the solution and reacted for 5 h to obtain the SA@UiO-68@(Zr)-S-Si composite phase change material.

[0079] 3.0 g of SA@UiO-68@(Zr)-S-Si and 1.5 g of TEOS were added to 40 mL of formamide solution and magnetically stirred for 30 min. Then, 0.1 mol / L HCl solution was added dropwise to adjust the pH of the system to 3.5. The system was magnetically stirred at 25 °C for 7 days and washed with anhydrous ethanol and filtered to obtain SA@UiO-68@(Zr)-S-Si@SiO 2 Composite phase change materials.

[0080] The results show that SA@UiO-68@(Zr)-S-Si@SiO 2 The melting enthalpy of SA@UiO-68@(Zr)-S-Si@SiO 2 The melt permeability can reach 1.06%, which is 38.81% lower than that of SA@UiO-68.

[0081] Example 8

[0082] Take MIL-101(Fe) as carrier; stearic acid as phase change material, the dosage is 150% of MIL-101(Fe); the mass of tetraethyl orthosilicate is 50% of SA@MIL-101(Fe)@(Fe)-S-Si as an example.

[0083] 0.382 g of terephthalic acid and 0.622 g of ferric chloride hexahydrate were dissolved in 60 mL of N, N-dimethylformamide, stirred magnetically at 25°C for 30 min, transferred to a hydrothermal reactor and reacted at 110°C for 24 h. The MIL-101 (Fe) carrier with unsaturated metal sites was obtained by washing and centrifuging with N, N-dimethylformamide and anhydrous ethanol, respectively, and dried by forced air at 80°C for 12 h and vacuum drying at 120°C for 12 h.

[0084] 1.62 g of stearic acid was dissolved in 30 mL of 90°C hot n-hexane under magnetic stirring. After 30 min, 1.08 g of MIL-101(Fe) was added to the solution and reacted for 4 h. 0.3 g of KH590 was added to the solution and reacted for 5 h to obtain SA@MIL-101(Fe)@(Fe)-S-Si composite phase change material.

[0085] 3.0 g of SA@MIL-101(Fe)@(Fe)-S-Si and 1.5 g of TEOS were added to 40 mL of formamide solution and dispersed under magnetic stirring for 30 min. Then, 0.1 mol / L HCl solution was added dropwise to adjust the pH of the system to 3.5. The system was magnetically stirred at 25 °C for 7 days and washed with anhydrous ethanol and filtered to obtain SA@MIL-101(Fe)@(Fe)-S-Si@SiO 2 Composite phase change materials.

[0086] The results show that SA@MIL-101(Fe)@(Fe)-S-Si@SiO 2 The melting enthalpy can reach 75.9 J / g. SA@MIL-101(Fe)@(Fe)-S-Si@SiO 2 The melt permeability can reach 1.77%, which is 32.96% higher than that of SA@MIL-101(Fe).

[0087] In summary, the content of the present invention is not limited to the above-mentioned embodiments, and people with insight in the same field can easily propose other embodiments within the technical guiding ideology of the present invention, but such embodiments are all included in the scope of the present invention.

Claims

1. A method for preparing a MOFs-based composite phase change material, Features The method comprises the following contents: (1) mixing a soluble metal salt, an organic ligand and a solvent, and then carrying out a synthesis reaction, washing, separating, drying and then carrying out an activation treatment on the product after hydrothermal treatment to obtain a MOFs carrier with unsaturated metal sites; (2) adding the MOFs carrier with unsaturated metal sites obtained in step (1) into a solution containing a soluble phase change material and immersing it for a period of time, then adding a silane coupling agent and continuing the reaction for a period of time, and then drying to obtain a composite phase change material precursor; (3) carrying out a condensation reaction between the composite phase change material precursor and a silicon dioxide precursor in formamide, filtering and drying the reaction product to obtain a MOFs-based composite phase change material.

2. The method according to claim 1, Features: The soluble metal salt described in step (1) is selected from one or more of chromium nitrate, ferric nitrate, ferric chloride, copper nitrate and zirconium chloride.

3. The method according to claim 1, Features: The organic ligand described in step (1) is selected from one or more of terephthalic acid, 2-aminoterephthalic acid, trimesic acid and dicarboxylic acid terphenyl.

4. The method according to claim 1, Features: The solvent described in step (1) and step (2) is selected from one or more of water, N,N-dimethylformamide, anhydrous ethanol, methanol, dimethyl sulfoxide, n-hexane and n-pentane.

5. The method according to claim 1, Features: The mass ratio of the soluble metal salt, the organic ligand and the solvent in step (1) is (4.1-1.5):1:(33.3-117.6).

6. The method according to claim 1, Features: The reaction conditions of step (1) are: reaction at 30-180° C. for 5-24 hours, and the reaction is carried out under stirring conditions.

7. The method according to claim 1, Features: The drying conditions in step (1) are as follows: drying temperature is 80 to 120° C. and drying time is 4 to 24 hours.

8. The method according to claim 1, Features: The activation treatment method described in step (1) can be vacuum drying, chemical activation, or photothermal activation.

9. The method according to claim 1, Features: The soluble phase change material described in step (2) is selected from one or more of stearic acid, lauric acid, palmitic acid, octadecyl alcohol, polyethylene glycol 2000, polyethylene glycol 4000, polyethylene glycol 6000, 52# paraffin, 28# paraffin, n-hexadecane, n-octadecane and n-docosane.

10. The method according to claim 1, Features: The solvent used in the solution containing the soluble phase change material in step (2) is selected from one or more of water, N,N-dimethylformamide, anhydrous ethanol, methanol, dimethyl sulfoxide, n-hexane, and n-pentane; the concentration of the solution is 0.01 g / mL to 0.5 g / mL.

11. The method according to claim 1, Features: The mass ratio of the MOFs carrier to the soluble phase change material in step (2) is 1-1:4-1.

12. The method according to claim 1, Features: The immersion time in step (2) is 1 to 4 hours.

13. The method according to claim 1, Features: The silane coupling agent described in step (2) is one or more of mercaptopropyl triethoxysilane, mercaptopropyl triethoxysilane, aminopropyl triethoxysilane, and aminopropyl trimethoxysilane.

14. The method according to claim 1, Features: The reaction time after adding the silane coupling agent in step (2) is 3 to 5 hours.

15. The method according to claim 1, Features: The silicon dioxide precursor described in step (3) is selected from one or more of tetraethyl orthosilicate, methyltriethoxysilane, propyltriethoxysilane and octyltriethoxysilane.

16. The method according to claim 1, Features: The mass ratio of the composite phase change material precursor to the silicon dioxide precursor in step (3) is 1-1:3-1.

17. The method according to claim 1, Features: The polycondensation reaction conditions in step (3) are: reaction time 1 to 7 days, pH value 2.5 to 4, reaction temperature at room temperature, and the reaction is generally carried out under stirring conditions.

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