An electric heating material based on modified blue carbon powder containing carbon nanotubes and doped waste bagasse and its preparation method

Abstract

The present invention discloses an electric heating material based on modified blue charcoal powder containing carbon nanotubes doped with waste bagasse and a preparation method thereof. The electric heating material is prepared by homogenizing, filtering and drying a cellulose solution containing lignin prepared from waste bagasse and modified blue charcoal powder containing carbon nanotubes prepared by catalytic microwave pyrolysis of low-order pulverized coal. The modified blue charcoal powder containing carbon nanotubes is a conductive filler for the electric heating material, and its preparation process greatly reduces the cost and time of preparing the conductive filler; the cellulose containing lignin is the matrix material of the electric heating material, and its raw material source is wide and inexpensive. The electric heating material has the characteristics of being cheap, light in weight, and having excellent electric-to-heat conversion efficiency, and can be applied to electric heating films, electric floor heating, wearable physiotherapy products, and the like.

Description

Technical Field

[0001] The present invention belongs to the field of material preparation, and in particular relates to an electric heating material based on modified blue charcoal containing carbon nanotubes and doped with waste bagasse, and a preparation method thereof. Background Art

[0002] At present, heating is mainly based on the combustion of fossil resources to generate heat. This process is bound to cause a large amount of carbon emissions, environmental pollution and resource utilization problems. "Replacing coal with electricity to generate heat" is a new concept to solve the above problems caused by the traditional combustion of fossil resources to generate heat. It is also one of the important measures to save energy and reduce emissions and control carbon emissions. The key to the new clean heat generation method of converting electrical energy into thermal energy lies in the preparation of electric heating materials. Existing carbon-based electric heating materials are used in the field of medium and low temperature heating. They mainly use carbon black, carbon fiber, graphene, carbon crystals, etc. as conductive fillers. Although they have the advantages of acid and alkali corrosion resistance, oxidation resistance, high electric heat conversion efficiency, and light weight, they have disadvantages such as high price and complex preparation process.

[0003] Low-grade pulverized coal is a cheap coal resource that is difficult to utilize at present. Its annual output is astonishing, but its high-value utilization channels are relatively single. Summary of the Invention

[0004] In order to solve the problems existing in the prior art, the purpose of the present invention is to provide an electric heating material based on modified blue charcoal containing carbon nanotubes and doped waste sugarcane bagasse and a preparation method thereof. The present invention modifies low-rank pulverized coal into high-value modified carbon material as a conductive filler for the electric heating material, which can greatly improve the utilization value of the low-rank pulverized coal.

[0005] The technical solution adopted in the present invention is as follows:

[0006] A method for preparing an electric heating material based on modified semi-coke containing carbon nanotubes and doped with waste bagasse comprises the following steps:

[0007] The cellulose solution containing lignin and the modified blue charcoal powder containing carbon nanotubes are homogeneously mixed, filtered, dried, and peeled to obtain the electric heating material based on the modified blue charcoal powder containing carbon nanotubes and doped with waste sugarcane bagasse;

[0008] The cellulose solution containing lignin was obtained by decomposing sugarcane bagasse with formic acid;

[0009] The preparation process of modified semi-coke powder containing carbon nanotubes includes:

[0010] The low-grade coal is added to an ethanol solution containing Fe(NO3)3, mixed evenly to form a dispersion, and then dried to obtain a mixed low-grade pulverized coal containing Fe(NO3)3;

[0011] Adding KOH solution to the mixed low-rank pulverized coal containing Fe(NO3)3, mixing uniformly to form a dispersion, and then drying to obtain a mixed low-rank pulverized coal containing Fe(NO3)3 and KOH;

[0012] The mixed low-rank pulverized coal containing Fe(NO3)3 and KOH is subjected to microwave pyrolysis to generate carbon nanotubes in the mixed low-rank pulverized coal containing Fe(NO3)3 and KOH. After the pyrolysis is completed, the obtained solid product is washed to neutrality and then dried to obtain the modified lignite powder containing carbon nanotubes.

[0013] Preferably, the particle size of the low-metamorphic coal is below 200 mesh.

[0014] Preferably, when preparing modified semi-coke powder containing carbon nanotubes, the mass ratio of low-metamorphosis coal, Fe(NO3)3, and KOH is (2.5-10):(0.125-0.5):(0.1-2).

[0015] Preferably, when the mixed low-rank pulverized coal containing Fe(NO3)3 and KOH is subjected to microwave pyrolysis, the microwave power is 560-1200W and the microwave pyrolysis time is 20-60min.

[0016] Preferably, the preparation process of the lignin-containing cellulose solution comprises:

[0017] The crushed sugarcane bagasse and formic acid are mixed at a mass / volume ratio of 1:(12-45) g / mL, and then stirred for reaction. After the reaction, the treated product is repeatedly washed with deionized water until it is neutral, and then a preset amount of deionized water is added to obtain a suspension. The concentration of the suspension is adjusted to a mass concentration of 0.35% to 0.75%, and then the suspension is homogenized to obtain the lignin-containing cellulose solution.

[0018] Preferably, when the suspension is homogenized, the suspension is homogenized by a high-speed disperser at 8000-12000 rpm.

[0019] Preferably, the mass volume ratio of the modified blue charcoal powder containing carbon nanotubes to the cellulose solution containing lignin is (1-5):(5-9).

[0020] Preferably, when the cellulose solution containing lignin is homogeneously mixed with the modified blue carbon powder containing carbon nanotubes:

[0021] The stirring rate is 500-1200 rpm, and the mixing time is 2-6 hours;

[0022] The drying temperature after filtration is 50-80°C.

[0023] The present invention also provides an electric heating material based on modified blue charcoal containing carbon nanotubes doped with waste bagasse, and the thermoelectric material is prepared by the preparation method of the present invention as described above.

[0024] Preferably, the electric heating material based on the modified blue charcoal containing carbon nanotubes and doped with waste bagasse has a resistance of 200 to 500 Ω / cm at room temperature. -2 , at a voltage of 12 to 36V, the maximum temperature is 25 to 75°C.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] The raw materials used in the technical solution of the present invention are cheap, difficult-to-use or waste materials. The modified blue charcoal powder containing carbon nanotubes is prepared by catalytic microwave pyrolysis as a conductive filler, and the modified blue charcoal powder containing carbon nanotubes is filled into a cellulose-based material containing lignin prepared from waste sugarcane bagasse, and then the electric heating material is formed by homogenizing, mixing, filtering and drying. The preparation method of the present invention greatly reduces the cost and preparation time of the conductive filler, and the prepared electric heating material has the characteristics of being cheap, light in weight, and having excellent electric heat conversion efficiency. In addition, the raw material source range of the present invention is relatively wide. In addition to the waste sugarcane bagasse described in the present invention, other cellulose-rich biomass can be used as the raw material of the electric heating material. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a microscopic morphology of the modified semi-coke powder containing carbon nanotubes used in Example 1 of the present invention at 2000 times magnification;

[0028] Figure 2 This is a microscopic morphology of the modified semi-coke powder containing carbon nanotubes used in Example 1 of the present invention at a magnification of 4000 times. DETAILED DESCRIPTION

[0029] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0030] Coal is rich in aromatic carbon structures, and modified semi-coke containing carbon nanotubes can be produced through catalytic microwave pyrolysis. This invention modifies low-rank pulverized coal into a high-value modified carbon material, which can be used as a conductive filler for electric heating materials, significantly increasing their utility. Therefore, the present invention prepares modified semi-coke powder through catalytic microwave pyrolysis of low-rank pulverized coal, and then fills this material into a waste bagasse-based material, producing an inexpensive, lightweight electric heating material with excellent electric-to-heat conversion efficiency.

[0031] The electric heating material based on modified blue charcoal powder containing carbon nanotubes and doped with waste bagasse is prepared by homogeneously mixing, filtering, drying and peeling a cellulose solution containing lignin prepared from waste bagasse and modified blue charcoal powder containing carbon nanotubes prepared by catalytic microwave pyrolysis of low-order pulverized coal.

[0032] Specifically, the process for preparing a cellulose solution containing lignin from waste bagasse of the present invention is as follows: crushed waste bagasse and formic acid are mixed at a mass / volume ratio of 1:(12-45) g / mL, and treated at 75-105°C and 500-700 rpm for 4-10 hours under mechanical stirring conditions to allow for sufficient reaction. The treated product is repeatedly washed with deionized water until neutral, and a certain amount of deionized water is added to adjust the suspension concentration to a mass concentration of 0.35% to 0.75%. The suspension is homogenized in a high-speed disperser at 8000-12000 rpm for five minutes each time, for a total of ten times, to obtain a cellulose solution containing lignin.

[0033] The modified semi-coal powder containing carbon nanotubes is prepared by catalytic microwave pyrolysis of low-rank pulverized coal as follows: 2.5-10 g of 200-mesh low-grade coal from northern Shaanxi is added to an ethanol solution containing 0.125-0.5 g of Fe(NO3)3, stirred at a constant temperature of 40-80°C for 2-6 hours, and then dried to produce a mixed low-rank pulverized coal containing Fe(NO3)3. 0.5-10 g of a 20% KOH solution (mass fraction) is then dropwise added to the mixed low-rank pulverized coal containing Fe(NO3)3. After stirring at a constant temperature of 40-80°C for 4-8 hours, the mixture is thoroughly dried to produce a mixed low-rank pulverized coal containing Fe(NO3)3 and KOH. The mixed low-rank pulverized coal containing Fe(NO3)3 and KOH is microwave pyrolyzed at a microwave power of 560-1200 W for 30-60 minutes. After the pyrolysis is complete, the resulting solid product is washed to neutrality and dried to produce the modified semi-coal powder containing carbon nanotubes.

[0034] The preparation method of the electric heating material based on modified blue charcoal containing carbon nanotubes and doped with waste bagasse comprises the following steps:

[0035] The modified semi-coke powder containing carbon nanotubes is added to the cellulose solution containing lignin, mixed and stirred homogeneously, and then vacuum filtered to form a sheet material. The sheet material is peeled and dried to obtain the electric heating material based on the modified semi-coke powder containing carbon nanotubes and doped with waste sugarcane bagasse.

[0036] In the above-mentioned preparation method of the present invention, the mass volume ratio of the modified blue charcoal powder containing carbon nanotubes and the cellulose solution containing lignin is (1-5): (5-9), the homogenizing mixing stirring rate is 500-1200 rpm, the mixing stirring time is 2-6 hours, and when peeling and drying the sheet material, it needs to be clamped and dried at 50-80°C with a glass plate clamp.

[0037] Example 1

[0038] This embodiment is based on the electric heating material of modified blue charcoal powder containing carbon nanotubes doped with waste sugarcane bagasse. The electric heating material is made by homogenizing, filtering, drying and stripping the cellulose solution containing lignin prepared from waste sugarcane bagasse and the modified blue charcoal powder containing carbon nanotubes prepared by catalytic microwave pyrolysis of low-order pulverized coal.

[0039] The lignin-containing cellulose solution used in this example was prepared as follows: pulverized waste bagasse and formic acid were mixed at a mass / volume ratio of 1:30 g / mL and treated at 95°C with mechanical stirring at 500 rpm for 8 hours. The treated product was washed with deionized water until neutral, and deionized water was added to adjust the suspension concentration to 0.5% by mass. The suspension was homogenized in a high-speed disperser at 10,000 rpm for five minutes each, for a total of ten times, to obtain a lignin-containing cellulose solution.

[0040] The process of preparing modified semi-coal powder containing carbon nanotubes used in this embodiment is as follows: 5 g of 200 mesh low-grade coal from northern Shaanxi is added to an ethanol solution containing 0.25 g of Fe(NO3)3, stirred at a constant temperature of 60°C for 4 hours, and then dried to obtain a mixed low-grade pulverized coal containing Fe(NO3)3. Then, 5 g of KOH solution (mass concentration of 20%) is added dropwise to the mixed low-grade pulverized coal containing Fe(NO3)3, stirred at a constant temperature of 60°C for 6 hours, and then dried to obtain a mixed low-grade pulverized coal containing Fe(NO3)3 and KOH. The mixed low-grade pulverized coal containing Fe(NO3)3 and KOH is pyrolyzed by microwave at a microwave power of 700 W for 40 minutes. After the pyrolysis is completed, the obtained solid product is washed to neutrality and dried to obtain modified semi-coal powder containing carbon nanotubes. See Figure 1 and Figure 2 , indicating that carbon nanotubes are generated in the modified semi-coke powder containing carbon nanotubes used in the embodiment of the present invention.

[0041] The specific preparation process conditions for preparing the electric heating material of this embodiment by combining a cellulose solution containing lignin with modified blue charcoal powder containing carbon nanotubes include: a mass volume ratio of the modified blue charcoal powder to the cellulose solution containing lignin of 1:9, a homogenizing stirring rate of 500 rpm, a mixing stirring time of 2 hours, and a drying process of the sheet material by clamping it with a glass plate at 50°C. Under these conditions, the electric heating material prepared has a resistance of 500 Ω / cm at room temperature. -2 , at 36V voltage, the maximum temperature is 25℃.

[0042] Example 2

[0043] This embodiment is based on the electric heating material of modified blue charcoal powder containing carbon nanotubes doped with waste sugarcane bagasse. The electric heating material is made by homogenizing, filtering, drying and stripping the cellulose solution containing lignin prepared from waste sugarcane bagasse and the modified blue charcoal powder containing carbon nanotubes prepared by catalytic microwave pyrolysis of low-order pulverized coal.

[0044] The lignin-containing cellulose solution used in this example was prepared as follows: pulverized waste bagasse and formic acid were mixed at a mass / volume ratio of 1:30 g / mL and treated at 95°C with mechanical stirring at 500 rpm for 8 hours. The treated product was washed with deionized water until neutral, and deionized water was added to adjust the suspension concentration to 0.5% by mass. The suspension was homogenized in a high-speed disperser at 10,000 rpm for five minutes each, for a total of ten times, to obtain a lignin-containing cellulose solution.

[0045] The modified semi-coal powder containing carbon nanotubes used in this example is produced as follows: 5g of 200-mesh low-grade coal from northern Shaanxi was added to an ethanol solution containing 0.25g of Fe(NO3)3, stirred at 60°C for 4 hours, and then dried to produce a mixed low-grade pulverized coal containing Fe(NO3)3. 5g of a 20% KOH solution was then dropwise added to the mixed low-grade pulverized coal containing Fe(NO3)3. After stirring at 60°C for 6 hours, the mixture was dried to produce a mixed low-grade pulverized coal containing Fe(NO3)3 and KOH. The mixed low-grade pulverized coal containing Fe(NO3)3 and KOH was then pyrolyzed at a microwave power of 700W for 40 minutes. After the pyrolysis was complete, the resulting solid product was washed to neutrality and dried to produce the modified semi-coal powder containing carbon nanotubes.

[0046] The specific preparation process conditions for preparing the electric heating material of this embodiment by combining a cellulose solution containing lignin with modified blue charcoal powder containing carbon nanotubes include: a mass volume ratio of the modified blue charcoal powder to the cellulose solution containing lignin of 2:8, a homogenizing stirring rate of 800 rpm, a mixing time of 5 hours, and a drying process of the sheet material at 70°C using a glass plate clamp. Under these conditions, the prepared electric heating material has a resistivity of 352 Ω / cm at room temperature. -2 , at 36V voltage, the maximum temperature is 42℃.

[0047] Example 3

[0048] This embodiment is based on the electric heating material of modified blue charcoal powder containing carbon nanotubes doped with waste sugarcane bagasse. The electric heating material is made by homogenizing, filtering, drying and stripping the cellulose solution containing lignin prepared from waste sugarcane bagasse and the modified blue charcoal powder containing carbon nanotubes prepared by catalytic microwave pyrolysis of low-order pulverized coal.

[0049] The lignin-containing cellulose solution used in this example was prepared as follows: pulverized waste bagasse and formic acid were mixed at a mass / volume ratio of 1:30 g / mL and treated at 95°C with mechanical stirring at 500 rpm for 8 hours. The treated product was washed with deionized water until neutral, and deionized water was added to adjust the suspension concentration to 0.5% by mass. The suspension was homogenized in a high-speed disperser at 10,000 rpm for five minutes each, for a total of ten times, to obtain a lignin-containing cellulose solution.

[0050] The modified semi-coal powder containing carbon nanotubes used in this example is produced as follows: 5g of 200-mesh low-grade coal from northern Shaanxi was added to an ethanol solution containing 0.25g of Fe(NO3)3, stirred at 60°C for 4 hours, and then dried to produce a mixed low-grade pulverized coal containing Fe(NO3)3. 5g of a 20% KOH solution was then dropwise added to the mixed low-grade pulverized coal containing Fe(NO3)3. After stirring at 60°C for 6 hours, the mixture was dried to produce a mixed low-grade pulverized coal containing Fe(NO3)3 and KOH. The mixed low-grade pulverized coal containing Fe(NO3)3 and KOH was then pyrolyzed at a microwave power of 700W for 40 minutes. After the pyrolysis was complete, the resulting solid product was washed to neutrality and dried to produce the modified semi-coal powder containing carbon nanotubes.

[0051] The specific preparation process conditions for preparing the electric heating material of this embodiment by combining a cellulose solution containing lignin with modified blue charcoal powder containing carbon nanotubes include: a mass volume ratio of the modified blue charcoal powder to the cellulose solution containing lignin of 5:5, a homogenizing stirring rate of 1200 rpm, a mixing stirring time of 6 hours, and a drying process of the sheet material by clamping it with a glass plate at 80°C. Under these conditions, the electric heating material prepared has a resistance of 200Ω / cm at room temperature. -2 , at 36V voltage, the maximum temperature is 75℃.

[0052] Example 4

[0053] This embodiment is based on the electric heating material of modified blue charcoal powder containing carbon nanotubes doped with waste sugarcane bagasse. The electric heating material is made by homogenizing, filtering, drying and stripping the cellulose solution containing lignin prepared from waste sugarcane bagasse and the modified blue charcoal powder containing carbon nanotubes prepared by catalytic microwave pyrolysis of low-order pulverized coal.

[0054] The lignin-containing cellulose solution used in this example was prepared as follows: pulverized waste bagasse and formic acid were mixed at a mass / volume ratio of 1:12 g / mL and treated at 75°C with mechanical stirring at 500 rpm for 4 hours. The treated product was washed with deionized water until neutral, and deionized water was added to adjust the suspension concentration to 0.35% by mass. The suspension was homogenized using a high-speed disperser at 8000 rpm for five minutes each, for a total of ten times, to obtain a lignin-containing cellulose solution.

[0055] The modified semi-coal powder containing carbon nanotubes used in this example is produced as follows: 2.5 g of 200-mesh Shaanxi low-grade coal is added to an ethanol solution containing 0.125 g of Fe(NO3)3, stirred at 40°C for 2 hours, and then dried to produce a mixed low-grade pulverized coal containing Fe(NO3)3. 0.5 g of a 20% KOH solution (mass concentration) is then dropwise added to the mixed low-grade pulverized coal containing Fe(NO3)3. After stirring at 40°C for 4 hours, the mixture is dried to produce a mixed low-grade pulverized coal containing Fe(NO3)3 and KOH. The mixed low-grade pulverized coal containing Fe(NO3)3 and KOH is then microwave-pyrolyzed at a microwave power of 560 W for 60 minutes. After the pyrolysis is complete, the resulting solid product is washed to neutrality and dried to produce the modified semi-coal powder containing carbon nanotubes.

[0056] The specific preparation process conditions for preparing the electric heating material of this embodiment by combining a cellulose solution containing lignin with modified blue charcoal powder containing carbon nanotubes include: a mass volume ratio of the modified blue charcoal powder to the cellulose solution containing lignin of 5:5, a homogenizing stirring rate of 1200 rpm, a mixing time of 6 hours, and a drying process of the sheet material by clamping and drying it at 80°C using a glass plate clamp. Under these conditions, the prepared electric heating material has a resistance of 450Ω / cm at room temperature. -2 , at 24V voltage, the maximum temperature is 38℃.

[0057] Example 5

[0058] This embodiment is based on the electric heating material of modified blue charcoal powder containing carbon nanotubes doped with waste sugarcane bagasse. The electric heating material is made by homogenizing, filtering, drying and stripping the cellulose solution containing lignin prepared from waste sugarcane bagasse and the modified blue charcoal powder containing carbon nanotubes prepared by catalytic microwave pyrolysis of low-order pulverized coal.

[0059] The lignin-containing cellulose solution used in this example was prepared as follows: pulverized waste bagasse and formic acid were mixed at a mass / volume ratio of 1:45 g / mL and treated at 105°C with mechanical stirring at 700 rpm for 10 hours. The treated product was washed with deionized water until neutral, and deionized water was added to adjust the suspension concentration to 0.75% by mass. The suspension was homogenized in a high-speed disperser at 12,000 rpm for five minutes each, for a total of ten times, to obtain a lignin-containing cellulose solution.

[0060] The modified semi-coal powder containing carbon nanotubes used in this embodiment is produced as follows: 10g of 200-mesh low-grade coal from northern Shaanxi is added to an ethanol solution containing 0.5g of Fe(NO3)3, stirred at 80°C for 6 hours, and then dried to produce a mixed low-grade pulverized coal containing Fe(NO3)3. 10g of a 20% KOH solution (mass concentration) is then dropwise added to the mixed low-grade pulverized coal containing Fe(NO3)3. After stirring at 80°C for 8 hours, the mixture is dried to produce a mixed low-grade pulverized coal containing Fe(NO3)3 and KOH. The mixed low-grade pulverized coal containing Fe(NO3)3 and KOH is then pyrolyzed at a microwave power of 1200W for 30 minutes. After the pyrolysis is complete, the resulting solid product is washed to neutrality and dried to produce modified semi-coal powder containing carbon nanotubes.

[0061] The specific preparation process conditions for preparing the electric heating material of this embodiment by combining a cellulose solution containing lignin with modified blue charcoal powder containing carbon nanotubes include: a mass volume ratio of the modified blue charcoal powder to the cellulose solution containing lignin of 5:5, a homogenizing stirring rate of 1200 rpm, a mixing stirring time of 6 hours, and a drying process of the sheet material by clamping it with a glass plate at 80°C. Under these conditions, the electric heating material prepared has a resistance of 200Ω / cm at room temperature. -2 , at 36V voltage, the maximum temperature is 70℃.

[0062] Example 6

[0063] This embodiment is based on the electric heating material of modified blue charcoal powder containing carbon nanotubes doped with waste sugarcane bagasse. The electric heating material is made by homogenizing, filtering, drying and stripping the cellulose solution containing lignin prepared from waste sugarcane bagasse and the modified blue charcoal powder containing carbon nanotubes prepared by catalytic microwave pyrolysis of low-order pulverized coal.

[0064] The lignin-containing cellulose solution used in this example was prepared as follows: pulverized waste bagasse and formic acid were mixed at a mass / volume ratio of 1:25 g / mL and treated at 75°C with mechanical stirring at 750 rpm for 9 hours. The treated product was washed with deionized water until neutral, and deionized water was added to adjust the suspension concentration to 0.6% by mass. The suspension was homogenized using a high-speed disperser at 9000 rpm for five minutes each, for a total of ten times, to obtain a lignin-containing cellulose solution.

[0065] The modified semi-coal powder containing carbon nanotubes used in this example is produced as follows: 5g of 200-mesh low-grade coal from northern Shaanxi was added to an ethanol solution containing 0.25g of Fe(NO3)3, stirred at 60°C for 4 hours, and then dried to produce a mixed low-grade pulverized coal containing Fe(NO3)3. 5g of a 20% KOH solution was then dropwise added to the mixed low-grade pulverized coal containing Fe(NO3)3. After stirring at 80°C for 8 hours, the mixture was dried to produce a mixed low-grade pulverized coal containing Fe(NO3)3 and KOH. The mixed low-grade pulverized coal containing Fe(NO3)3 and KOH was then pyrolyzed at a microwave power of 640W for 30 minutes. After the pyrolysis was complete, the resulting solid product was washed to neutrality and dried to produce the modified semi-coal powder containing carbon nanotubes.

[0066] The specific preparation process conditions for preparing the electric heating material of this embodiment by combining a cellulose solution containing lignin with modified blue charcoal powder containing carbon nanotubes include: a mass volume ratio of the modified blue charcoal powder to the cellulose solution containing lignin of 5:5, a homogenizing stirring rate of 1200 rpm, a mixing stirring time of 6 hours, and a drying process of the sheet material at 80°C using a glass plate clamp. Under these conditions, the prepared electric heating material has a resistance of 240 Ω / cm at room temperature. -2 , at 12V voltage, the maximum temperature is 54℃.

[0067] From the above, it can be seen that the electric heating material prepared by the method of the present invention has a resistance of 200 to 500 Ω / cm at room temperature. -2 , at a voltage of 12 to 36 V, the maximum temperature is 25 to 75°C, with good electrothermal performance.

[0068] The above embodiments are intended to illustrate the technical solutions of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the embodiments, those skilled in the art will appreciate that modifications or equivalent substitutions to the present invention that do not depart from the spirit and scope of the present invention are intended to be encompassed within the scope of the present invention. In addition, unless otherwise specified, all or part of any embodiment may be used in combination with all or part of any other embodiment.

Claims

1. A method for preparing an electric heating material based on modified blue charcoal containing carbon nanotubes and doped with waste bagasse, characterized in that: The process includes the following: The cellulose solution containing lignin and the modified blue charcoal powder containing carbon nanotubes are homogeneously mixed, filtered, dried, and peeled to obtain the electric heating material based on the modified blue charcoal powder containing carbon nanotubes and doped with waste sugarcane bagasse; The cellulose solution containing lignin was obtained by decomposing sugarcane bagasse with formic acid; The preparation process of modified semi-coke powder containing carbon nanotubes includes: The low-grade coal is added to an ethanol solution containing Fe(NO3)3, mixed evenly to form a dispersion, and then dried to obtain a mixed low-grade pulverized coal containing Fe(NO3)3; Adding KOH solution to the mixed low-rank pulverized coal containing Fe(NO3)3, mixing uniformly to form a dispersion, and then drying to obtain a mixed low-rank pulverized coal containing Fe(NO3)3 and KOH; The mixed low-rank pulverized coal containing Fe(NO3)3 and KOH is subjected to microwave pyrolysis to generate carbon nanotubes in the mixed low-rank pulverized coal containing Fe(NO3)3 and KOH. After the pyrolysis is completed, the obtained solid product is washed to neutrality and then dried to obtain the modified lignite powder containing carbon nanotubes.

2. The method for preparing an electric heating material based on modified blue charcoal containing carbon nanotubes and doped with waste bagasse according to claim 1, characterized in that: The particle size of the low metamorphic coal is below 200 meshes.

3. The method for preparing an electric heating material based on modified blue carbon powder containing carbon nanotubes and doped with waste bagasse according to claim 1, characterized in that: When preparing modified semi-coke powder containing carbon nanotubes, the mass ratio of low-metamorphosis coal, Fe(NO3)3, and KOH is (2.5-10):(0.125-0.5):(0.1-2).

4. The method for preparing an electric heating material based on modified blue charcoal containing carbon nanotubes and doped with waste bagasse according to claim 1, characterized in that: When the mixed low-rank pulverized coal containing Fe(NO3)3 and KOH is subjected to microwave pyrolysis, the microwave power is 560-1200W and the microwave pyrolysis time is 20-60min.

5. The method for preparing an electric heating material based on modified blue charcoal containing carbon nanotubes and doped with waste bagasse according to claim 1, characterized in that: The preparation process of the lignin-containing cellulose solution comprises: The crushed sugarcane bagasse and formic acid are mixed at a mass / volume ratio of 1:(12-45) g / mL, and then stirred for reaction. After the reaction, the treated product is repeatedly washed with deionized water until it is neutral, and then a preset amount of deionized water is added to obtain a suspension. The concentration of the suspension is adjusted to a mass concentration of 0.35% to 0.75%, and then the suspension is homogenized to obtain the lignin-containing cellulose solution.

6. The method for preparing an electric heating material based on modified blue charcoal containing carbon nanotubes and doped with waste bagasse according to claim 5, characterized in that: When the suspension is homogenized, the suspension is homogenized by passing it through a high-speed disperser at 8000 to 12000 rpm.

7. The method for preparing an electric heating material based on modified blue charcoal containing carbon nanotubes and doped with waste bagasse according to claim 5, characterized in that: The mass volume ratio of the modified blue charcoal powder containing carbon nanotubes and the cellulose solution containing lignin is (1-5): (5-9).

8. The method for preparing an electric heating material based on modified blue charcoal containing carbon nanotubes and doped with waste bagasse according to claim 5, characterized in that: When the cellulose solution containing lignin is homogeneously mixed with the modified semi-carbon powder containing carbon nanotubes: The stirring rate is 500-1200 rpm, and the mixing time is 2-6 hours; The drying temperature after filtration is 50-80°C.

9. An electric heating material based on modified blue charcoal containing carbon nanotubes and doped with waste bagasse, characterized in that: The electrothermal material is prepared by the preparation method according to any one of claims 1 to 8.

10. The electric heating material based on modified blue charcoal containing carbon nanotubes and doped with waste bagasse according to claim 9, characterized in that: The electric heating material based on the modified blue charcoal containing carbon nanotubes and doped with waste bagasse has a resistance of 200 to 500 Ω / cm at room temperature. -2 , at a voltage of 12 to 36V, the maximum temperature is 25 to 75°C.

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