Preparation method of flame-retardant heat-storage wood with high energy storage density

Abstract

A method for preparing flame-retardant, heat-storage wood with high energy storage density, belonging to the field of heat-storage wood, addresses the problem that adding flame retardants to existing heat-storage wood to address its flammability significantly reduces its energy storage density. The method includes: 1. preparing delignified wood; 2. preparing a cellulose wood skeleton; 3. preparing a composite flame-retardant phase change energy storage material; and 4. vacuum impregnation. This method is used to prepare flame-retardant, heat-storage wood with high energy storage density.

Description

Technical Field

[0001] The invention belongs to the field of heat storage wood. Background Art

[0002] Phase change materials, because they can utilize the phase change conversion process to store environmental energy such as excess waste heat in the form of latent heat, thereby reducing the consumption of non-renewable fuels, reducing carbon emissions, and achieving green and sustainable development. However, due to the problem of liquid phase leakage in actual use, phase change energy storage materials usually need to be solved by being adsorbed in a supporting material. As a natural biomass material, wood has a unique anisotropic porous structure, excellent mechanical strength, biodegradability, renewability, low cost, wide source, and environmental friendliness. Combining wood with phase change energy storage materials to construct heat storage wood is currently an effective way to solve the leakage problem of phase change energy storage materials. However, long-term phase change energy storage at high temperatures makes it difficult to avoid local overheating, which can cause risks such as fire and cause huge losses.

[0003] In previous studies, some flame retardants (such as montmorillonite, expanded graphite, magnesium hydroxide, red phosphorus, etc.) are usually added to heat storage wood to solve its flammability, but with the addition of flame retardant additives, the energy storage density will be greatly reduced. Summary of the Invention

[0004] The present invention aims to solve the problem that adding some flame retardants to existing heat storage wood to solve its flammability will greatly reduce the energy storage density, and further provide a preparation method of flame retardant heat storage wood with high energy storage density.

[0005] A method for preparing flame-retardant heat-storage wood with high energy storage density is carried out according to the following steps:

[0006] 1. Add the wood into the delignification solution and cook until the wood turns white, and finally wash it to obtain delignified wood;

[0007] Second, the delignified wood is placed in a NaOH solution and boiled to remove hemicellulose to obtain a cellulose wood skeleton;

[0008] 3. Mixing triphenyl phosphate and phase change energy storage material, heating and stirring, to obtain a composite flame retardant phase change energy storage material;

[0009] Fourth, the cellulose wood skeleton is impregnated into the composite flame-retardant phase change energy storage material by vacuum impregnation to obtain flame-retardant heat storage wood with high energy storage density.

[0010] The beneficial effects of the present invention are:

[0011] The high-energy-storage-density flame-retardant heat-storage wood of the present invention not only stores and releases heat and regulates ambient temperature, but is also flame-retardant, addressing the flammability drawback of conventional heat-storage wood and broadening its scope and applications. Furthermore, it features a simple preparation method, a short production cycle, minimal equipment requirements, and low cost, promising broad application prospects.

[0012] 1. The present invention removes lignin and hemicellulose and uses a cellulose wood skeleton as a supporting material, which not only retains the original three-dimensional porous structure and uses capillary force to limit the leakage of phase change energy storage materials, but also increases the specific surface area and porosity after removing lignin and hemicellulose, which can adsorb more phase change energy storage materials, thereby improving the energy storage density of the composite material.

[0013] 2. Triphenyl phosphate itself has both flame retardant properties and heat energy storage properties. With the addition of triphenyl phosphate, it will not only not reduce the energy storage density of heat storage wood, but also give it flame retardant properties.

[0014] 3. The present invention regulates the ratio of triphenyl phosphate to phase change energy storage material. As the content of phase change energy storage material increases, the supercooling of triphenyl phosphate can be reduced, thereby regulating the supercooling of the composite material, thereby improving the energy storage efficiency of the heat storage wood.

[0015] 4. The scheme of the present invention has high feasibility, simple operation process, short preparation cycle, mild reaction conditions, low cost, can realize large-scale industrial production and processing, and has very broad application prospects.

[0016] Figures in the specification

[0017] Figure 1 are SEM images, a is the delignified wood prepared in step 1 of Example 1, b is the flame-retardant heat storage wood with high energy storage density prepared in Example 1;

[0018] Figure 2 This is an EDS graph of the flame-retardant heat storage wood with high energy storage density prepared in Example 1;

[0019] Figure 3 This is a DSC curve diagram of the flame-retardant heat storage wood with high energy storage density prepared in Example 1;

[0020] Figure 4The composite flame-retardant phase-change energy storage material prepared in step 3 of Examples 1 to 5 and Comparative Experiments 1 to 6 is a physical picture after high-temperature melting and low-temperature cooling. (1) The composite flame-retardant phase-change energy storage material is taken out of the oven just after melting. (2) The composite flame-retardant phase-change energy storage material is cooled and allowed to stand for 30 minutes. a is 0:10 for Comparative Experiment 1, b is 1.1:10 for Example 2, c is 2.5:10 for Example 3, d is 4.3:10 for Example 1, e is 6.7:10 for Example 4, f is 10:10 for Example 5, g is 12:10 for Comparative Experiment 3, h is 23.3:10 for Comparative Experiment 4, i is 40:10 for Comparative Experiment 5, j is 90:10 for Comparative Experiment 6, and k is 10:0 for Comparative Experiment 2.

[0021] Figure 5 This is a picture of the combustion of the heat storage wood without triphenyl phosphate prepared in the first comparative experiment;

[0022] Figure 6 This is a picture of the flame-retardant heat storage wood with high energy storage density prepared in Example 1 self-extinguishing after combustion;

[0023] Figure 7 The heat release rate (HRR) curve of the cone calorimetry experiment of the heat storage wood without triphenyl phosphate prepared in comparative experiment 1 is shown;

[0024] Figure 8 The total heat release rate curve obtained from the cone calorimetry experiment of the heat storage wood without triphenyl phosphate prepared in comparative experiment 1 is shown in FIG.

[0025] Figure 9 This is the heat release rate curve measured by cone calorimetry experiment of the flame-retardant heat storage wood with high energy storage density prepared in Example 1;

[0026] Figure 10 This is the total heat release rate curve measured by the cone calorimetry experiment of the flame-retardant heat storage wood with high energy storage density prepared in Example 1. DETAILED DESCRIPTION

[0027] Specific embodiment 1: This embodiment is a method for preparing flame-retardant heat storage wood with high energy storage density, which is carried out according to the following steps:

[0028] 1. Add the wood into the delignification solution and cook until the wood turns white, and finally wash it to obtain delignified wood;

[0029] Second, the delignified wood is placed in a NaOH solution and boiled to remove hemicellulose to obtain a cellulose wood skeleton;

[0030] 3. Mixing triphenyl phosphate and phase change energy storage material, heating and stirring, to obtain a composite flame retardant phase change energy storage material;

[0031] Fourth, the cellulose wood skeleton is impregnated into the composite flame-retardant phase change energy storage material by vacuum impregnation to obtain flame-retardant heat storage wood with high energy storage density.

[0032] This specific embodiment proposes to use delignified and de-hemicellulosed wood skeleton as the supporting material, which effectively solves the problem of liquid leakage of phase change energy storage materials. By introducing triphenyl phosphate into the phase change energy storage material, the phase change energy storage performance and flame retardancy of triphenyl phosphate itself are utilized, which not only effectively improves the flame retardancy of the heat storage wood, but also improves the energy storage density of the heat storage wood. In addition, the supercooling degree of triphenyl phosphate is large, which is not conducive to the occurrence of phase change heat energy storage and release. By combining with the phase change energy storage material, the supercooling degree of triphenyl phosphate can be greatly reduced. The flame retardant heat storage wood with high energy storage density prepared by the present invention not only has flame retardancy, solves the flammability problem of phase change energy storage materials and wood, but also has high energy storage density and excellent heat storage capacity, thereby efficiently regulating the ambient temperature and alleviating energy pressure.

[0033] The beneficial effects of this embodiment are:

[0034] The high-energy-density, flame-retardant, heat-storage wood of this embodiment not only stores and releases heat, regulating ambient temperature, but also exhibits flame retardancy, addressing the flammability drawback of existing heat-storage wood and broadening its scope and applications. Furthermore, it features a simple preparation method, a short production cycle, minimal equipment requirements, and low cost, promising broad application prospects.

[0035] 1. This embodiment removes lignin and hemicellulose and uses a cellulose wood skeleton as a supporting material, which not only retains the original three-dimensional porous structure and uses capillary force to limit the leakage of phase change energy storage materials, but also increases the specific surface area and porosity after removing lignin and hemicellulose, which can adsorb more phase change energy storage materials, thereby improving the energy storage density of the composite material.

[0036] 2. Triphenyl phosphate itself has both flame retardant properties and heat energy storage properties. With the addition of triphenyl phosphate, it will not only not reduce the energy storage density of heat storage wood, but also give it flame retardant properties.

[0037] 3. This embodiment regulates the ratio of triphenyl phosphate to phase change energy storage material. As the content of phase change energy storage material increases, the supercooling of triphenyl phosphate can be reduced, thereby regulating the supercooling of the composite material, thereby improving the energy storage efficiency of the heat storage wood.

[0038] 4. This embodiment has high feasibility, simple operation process, short preparation cycle, mild reaction conditions, low cost, can realize large-scale industrial production and processing, and has very broad application prospects.

[0039] Specific embodiment 2: This embodiment differs from specific embodiment 1 in that the delignified solution described in step 1 is prepared by preparing a 1% to 3% by mass NaClO2 solution, and then adjusting the pH to 1 to 6 with acetic acid to obtain a delignified solution. Other processes are the same as specific embodiment 1.

[0040] Specific embodiment 3: This embodiment differs from specific embodiment 1 or 2 in that the wood in step 1 is poplar, paulownia, balsa, basswood or birch. Other aspects are the same as specific embodiment 1 or 2.

[0041] Specific embodiment 4: This embodiment differs from Specific embodiments 1 to 3 in that, in step 1, the wood is added to the delignification solution and cooked until the wood turns white. Specifically, the wood is added to the delignification solution and cooked at a temperature of 80°C to 100°C for 2 to 12 hours. Other steps are the same as Specific embodiments 1 to 3.

[0042] Specific embodiment 5: This embodiment differs from specific embodiments 1 to 4 in that the cleaning in step 1 is specifically performed with distilled water at a temperature of 80° C. to 100° C. for 3 to 5 times. Other aspects are the same as specific embodiments 1 to 4.

[0043] Specific embodiment 6: This embodiment differs from Specific embodiments 1 to 5 in that, in step 2, the delignified wood is placed in a 5% to 8% by mass NaOH solution and cooked at 80°C to 100°C for 1 to 10 hours to obtain a cellulose wood skeleton. Other steps are the same as Specific embodiments 1 to 5.

[0044] Specific embodiment 7: This embodiment differs from specific embodiments 1 to 6 in that the phase change energy storage material in step 3 is polyethylene glycol, fatty acid or fatty alcohol phase change energy storage material. Other aspects are the same as specific embodiments 1 to 6.

[0045] Specific embodiment 8: This embodiment differs from specific embodiments 1 to 7 in that the heating and stirring in step 3 is carried out at a temperature of 50°C to 70°C and a stirring speed of 1000 rpm to 2000 rpm for 1 to 3 hours. Other steps are the same as specific embodiments 1 to 7.

[0046] Specific embodiment 9: This embodiment differs from specific embodiments 1 to 8 in that the mass ratio of triphenyl phosphate to phase change energy storage material in step 3 is (1-10):10. Other aspects are the same as specific embodiments 1 to 8.

[0047] Specific embodiment 10: This embodiment differs from specific embodiments 1 to 9 in that the vacuum impregnation in step 4 is carried out at a temperature of 30°C to 100°C and a pressure of 0.06 MPa to 0.08 MPa for 1 to 5 hours. Other steps are the same as specific embodiments 1 to 9.

[0048] The following examples are used to verify the beneficial effects of the present invention:

[0049] Example 1:

[0050] A method for preparing flame-retardant heat-storage wood with high energy storage density is carried out according to the following steps:

[0051] First, add the wood into the delignification solution and cook it at 80℃ for 10 hours until the wood turns white. Finally, wash it with distilled water at 80℃ for 5 times to obtain delignified wood.

[0052] 2. The delignified wood was placed in a 5% by mass NaOH solution and boiled at 80°C for 6 hours to remove hemicellulose and obtain a cellulose wood skeleton;

[0053] 3. Mixing triphenyl phosphate and phase change energy storage material, heating and stirring at a temperature of 60°C and a stirring speed of 1000 r / min for 2 hours to obtain a composite flame retardant phase change energy storage material;

[0054] 4. The cellulose wood skeleton was impregnated into the composite flame-retardant phase change energy storage material, and vacuum impregnation was performed for 3 hours at a temperature of 60°C and a pressure of 0.08 MPa to obtain a flame-retardant heat storage wood with high energy storage density.

[0055] The delignification solution described in step 1 is specifically prepared according to the following steps: preparing a 1% by mass NaClO2 solution, and then adjusting the pH to 4.6 with acetic acid to obtain a delignification solution.

[0056] The wood described in step 1 is balsa wood.

[0057] The phase change energy storage material described in step three is polyethylene glycol 2000.

[0058] The mass ratio of triphenyl phosphate (TPP) to phase change energy storage material (PEG) described in step 3 is 4.3:10;

[0059] Example 2: This example differs from Example 1 in that the mass ratio of triphenyl phosphate to phase change energy storage material in step 3 is 1.1:10. Other steps are the same as Example 1.

[0060] Example 3: This example differs from Example 1 in that the mass ratio of triphenyl phosphate to phase change energy storage material in step 3 is 2.5:10. Other steps are the same as Example 1.

[0061] Example 4: This example differs from Example 1 in that the mass ratio of triphenyl phosphate to phase change energy storage material in step 3 is 6.7:10. Other steps are the same as Example 1.

[0062] Example 5: This example differs from Example 1 in that the mass ratio of triphenyl phosphate to phase change energy storage material in step 3 is 10:10. Other steps are the same as Example 1.

[0063] Comparative Experiment 1: This comparative experiment differs from Example 1 in that the mass ratio of triphenyl phosphate to phase change energy storage material in step 3 is 0:10. Other steps are the same as Example 1.

[0064] Comparative Experiment 2: This comparative experiment differs from Example 1 in that the mass ratio of triphenyl phosphate to phase change energy storage material in step 3 is 10:0. Other steps are the same as Example 1.

[0065] Comparative Experiment 3: This embodiment differs from the first embodiment in that the mass ratio of triphenyl phosphate to phase change energy storage material in step 3 is 12:10. Other steps are the same as those in the first embodiment.

[0066] Comparative Experiment 4: This embodiment differs from the first embodiment in that the mass ratio of triphenyl phosphate to phase change energy storage material in step 3 is 23.3:10. Other steps are the same as the first embodiment.

[0067] Comparative Experiment 5: This embodiment differs from the first embodiment in that the mass ratio of triphenyl phosphate to phase change energy storage material in step 3 is 40:10. Other steps are the same as the first embodiment.

[0068] Comparative Experiment 6: This embodiment differs from the first embodiment in that the mass ratio of triphenyl phosphate to phase change energy storage material in step 3 is 90:10. Other aspects are the same as those of the first embodiment.

[0069] Figure 1 are SEM images, a is the delignified wood prepared in step 1 of Example 1, b is the flame-retardant heat storage wood with high energy storage density prepared in Example 1; Figure 2This is an EDS image of the high-energy-density flame-retardant thermal storage wood prepared in Example 1. As can be seen, the delignified wood retains its original three-dimensional porous structure. After impregnation with triphenyl phosphate and the phase-change energy storage material, the pores in the delignified wood are completely filled, demonstrating the successful preparation of the high-energy-density flame-retardant thermal storage wood. Furthermore, EDS spectrum analysis reveals a carbon content of 51%, an oxygen content of 34%, and a phosphorus content of 5%, indicating that the triphenyl phosphate and the phase-change energy storage material are uniformly distributed throughout the high-energy-density flame-retardant thermal storage wood.

[0070] Figure 3 This is a DSC curve diagram of the flame-retardant heat storage wood with high energy storage density prepared in Example 1; as can be seen from the figure, the melting enthalpy of the heat storage wood is 121.4 kJ / kg and the crystallization enthalpy is 106.2 kJ / kg, indicating that it has a high energy storage density and good heat storage capacity.

[0071] Figure 4 The actual pictures of the composite flame-retardant phase-change energy storage materials prepared in step 3 of Examples 1 to 5 and Comparative Experiments 1 to 6 after high-temperature melting and low-temperature cooling, (1) the composite flame-retardant phase-change energy storage material is taken out of the oven just after melting, (2) the composite flame-retardant phase-change energy storage material is cooled and allowed to stand for 30 minutes, a is 0:10 in Comparative Experiment 1, b is 1.1:10 in Example 2, c is 2.5:10 in Example 3, d is 4.3:10 in Example 1, e is 6.7:10 in Example 4, f is 10:10 in Example 5, g is 12:10 in Comparative Experiment 3, h is 23.3:10 in Comparative Experiment 4, i is 40:10 in Comparative Experiment 5, j is 90:10 in Comparative Experiment 6, and k is 10:0 in Comparative Experiment 2; it can be seen from the figure that the supercooling degree of pure triphenyl phosphate is very large, but the supercooling degree decreases with the increase of the proportion of polyethylene glycol. In Example 1, the ratio of triphenyl phosphate to polyethylene glycol is 4.3:10, and the supercooling degree is small, which meets the experimental requirements.

[0072] Figure 5 This is a picture of the combustion of the heat storage wood without triphenyl phosphate prepared in comparative experiment 1. As can be seen from the picture, the heat storage wood without triphenyl phosphate continues to burn after leaving the flame, indicating that the heat storage wood is flammable.

[0073] Figure 6 This is a picture of the flame-retardant heat storage wood with high energy storage density prepared in Example 1 self-extinguishing after burning; as can be seen from the figure, the heat storage wood will self-extinguish after leaving the flame, indicating that it has good flame retardancy.

[0074] Figure 7The heat release rate (HRR) curve of the cone calorimetry experiment of the heat storage wood without triphenyl phosphate prepared in the comparative experiment 1 is shown in the figure. As can be seen from the figure, after the heat storage wood is ignited after 46 seconds, the typical maximum heat release peak appears at 246 seconds, and the maximum heat release peak is 583KW / m 2 .

[0075] Figure 8 The total heat release rate curve of the cone calorimetry experiment for the heat storage wood without triphenyl phosphate prepared in the comparative experiment 1 is shown in the figure. As can be seen from the figure, the heat storage wood was ignited after 46 seconds, and the total heat release rate data continued to increase until 510 seconds, reaching a maximum total heat release rate of 120.48MJ / m 2 , showing that thermal storage wood without triphenyl phosphate is flammable.

[0076] Figure 9 This is the heat release rate curve of the flame-retardant heat storage wood with high energy storage density prepared in Example 1 measured by cone calorimetry experiment; as can be seen from the figure, after the heat storage wood is ignited after 51 seconds, a typical maximum heat release peak appears at 222 seconds, and the maximum heat release peak is 402KW / m 2 .

[0077] Figure 10 This is the total heat release rate curve of the flame-retardant heat storage wood with high energy storage density prepared in Example 1 measured by cone calorimetry experiment; as can be seen from the figure, the heat storage wood was ignited after 51 seconds, and the total heat release rate data continued to increase until 435 seconds, reaching a maximum total heat release rate of 70.32 MJ / m 2 , compared with the heat storage wood without triphenyl phosphate, the total heat release rate is smaller, indicating that the addition of triphenyl phosphate gives the heat storage wood good flame retardancy.

[0078] The data of the cone calorimetry experiment are detailed in Table 1.

[0079] Table 1

[0080]

Claims

1. A method for preparing flame-retardant heat-storage wood with high energy storage density, characterized in that It is carried out in the following steps:

1. Add the wood into the delignification solution and cook until the wood turns white, and finally wash it to obtain delignified wood; Second, the delignified wood is placed in a NaOH solution and boiled to remove hemicellulose to obtain a cellulose wood skeleton; 3. Mixing triphenyl phosphate and phase change energy storage material, heating and stirring, to obtain a composite flame retardant phase change energy storage material; The mass ratio of triphenyl phosphate to phase change energy storage material is 4.3:10; the phase change energy storage material is polyethylene glycol 2000; Fourth, the cellulose wood skeleton is impregnated into the composite flame-retardant phase change energy storage material by vacuum impregnation to obtain flame-retardant heat storage wood with high energy storage density.

2. The method for preparing a flame-retardant heat-storage wood with high energy storage density according to claim 1, characterized in that The delignified solution described in step 1 is specifically prepared according to the following steps: preparing a NaClO2 solution with a mass percentage of 1% to 3%, and then adjusting the pH to 1 to 6 with acetic acid to obtain a delignified solution.

3. The method for preparing a flame-retardant heat-storage wood with high energy storage density according to claim 1, characterized in that The wood in step 1 is poplar, paulownia, balsa, basswood or birch.

4. The method for preparing a flame-retardant heat-storage wood with high energy storage density according to claim 1, characterized in that In step 1, the wood is added to the delignification solution and boiled until the wood turns white. The process is specifically carried out in the following steps: the wood is added to the delignification solution and boiled at a temperature of 80° C. to 100° C. for 2 h to 12 h.

5. The method for preparing a flame-retardant heat-storage wood with high energy storage density according to claim 1, characterized in that The cleaning described in step 1 is specifically cleaning 3 to 5 times with distilled water at a temperature of 80° C. to 100° C.

6. The method for preparing a flame-retardant heat-storage wood with high energy storage density according to claim 1, characterized in that In step 2, the delignified wood is placed in a NaOH solution with a mass percentage of 5% to 8%, and is soaked and boiled at a temperature of 80° C. to 100° C. for 1 hour to 10 hours to obtain a cellulose wood skeleton.

7. The method for preparing a flame-retardant heat-storage wood with high energy storage density according to claim 1, characterized in that The heating and stirring in step 3 is specifically carried out at a temperature of 50° C. to 70° C. and a stirring speed of 1000 r / min to 2000 r / min for 1 h to 3 h.

8. The method for preparing flame-retardant heat-storage wood with high energy storage density according to claim 1, characterized in that The vacuum impregnation in step 4 is carried out at a temperature of 30°C to 100°C and a pressure of 0.06MPa to 0.08MPa. a Under the conditions of vacuum impregnation for 1h to 5h.

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