Carbon nanotube-activated carbon composite material, and preparation method and application thereof

Abstract

The application discloses a carbon nanotube-activated carbon composite material and a preparation method and application thereof. The composite material comprises carbon nanotubes and activated carbon, and the weight loss ratio R of the composite material is 0.5-20. The preparation method of the composite material comprises the following steps: mixing petroleum coke, an activating agent and a transition metal compound and reacting; washing and drying the reaction product; treating the obtained material with polyhydric alcohol; further mixing the material with waste plastics and reacting; and washing and drying the reaction product to obtain the carbon nanotube-activated carbon composite material. The carbon nanotube-activated carbon composite material with excellent performance is obtained by comprehensively regulating a process route and reaction conditions with waste plastics and petroleum coke as raw materials.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of carbon-containing composite material preparation, and particularly relates to an activated carbon / carbon nanotube composite material and a preparation method and application thereof. BACKGROUND

[0002] Carbon nanotubes are one-dimensional nanomaterials mainly composed of carbon atoms in sp2 hybridization, and have excellent mechanical, electrical and chemical properties. In recent years, with the in-depth research of carbon nanotubes and nanomaterials, its broad application prospects have been constantly revealed. Carbon nanotubes have good mechanical properties, and the hardness is comparable to that of diamond, while they also have good flexibility. The P electrons of carbon atoms on the carbon nanotube form a large range of delocalized π bonds, and due to the existence of significant conjugation effect, the carbon nanotube exhibits specific electrical properties.

[0003] Activated carbon is a disordered porous carbon material, and due to its large specific surface area, rich pore structure and other characteristics, it has wide application prospects in the fields of adsorption separation, electrochemistry, energy storage, catalysis and the like. The carbon nanotube / activated carbon composite material can simultaneously have the advantages of both materials and exhibit excellent performance in some application fields.

[0004] Plastics are an important class of organic synthetic polymer materials. Since they were discovered, they have been widely used in various industries due to their durability, plasticity, low cost and other characteristics, greatly enriching and facilitating people's daily life. However, a large amount of waste plastics generated after use cannot be naturally degraded and are difficult to recycle, thereby causing "white pollution" that has irreversible harm to the natural environment and also causing a large amount of resource waste. Therefore, how to realize efficient and reasonable resource utilization of waste plastics has become a research hotspot in the field, and the preparation of high-value carbon nanotube products from waste plastics through catalytic pyrolysis is a utilization approach with great economic value.

[0005] Patent CN112408364A discloses a method for preparing carbon nanotubes by catalytic pyrolysis of waste thermosetting plastics. Fe@NiO core-shell catalyst is used, and waste thermosetting plastics are used as raw materials. The pyrolysis gas generated in the two-stage fixed bed reactor forms carbon nanotubes on the surface of the catalyst by controlling the reaction temperature. Patent CN104787747A discloses a preparation method and application of nanocarbon material. Plastic and other carbon chain polymer substances are used as raw materials, and nanocarbon material is prepared through three-stage microwave treatment under the action of a microwave catalyst. SUMMARY

[0006] In view of the deficiencies in the prior art, the main purpose of the present application is to provide a carbon nanotube-activated carbon composite material and a preparation method thereof, which uses waste plastics and petroleum coke as raw materials, and through comprehensive regulation of process routes and reaction conditions, a carbon nanotube-activated carbon composite material with excellent performance is obtained.

[0007] The first aspect of the present application provides a carbon nanotube-activated carbon composite material, the composite material comprising carbon nanotubes and activated carbon, the weight loss ratio R of the composite material being 0.5-20, preferably 1-10, wherein the weight loss ratio R of the composite material is calculated by the following formula: R=Am1 / Am2, wherein Am1 refers to the weight loss ratio before 660℃ in thermogravimetric analysis under oxygen condition, and Am2 refers to the weight loss ratio after 660℃.

[0008] Further, in the above-mentioned carbon nanotube-activated carbon composite material, the specific surface area of the composite material is 800-2500 m 2 / g, preferably 1000-2000 m 2 / g.

[0009] Further, in the above-mentioned carbon nanotube-activated carbon composite material, the carbon nanotubes are multi-walled carbon nanotubes, the average wall number of the multi-walled carbon nanotubes being 10-40, preferably 15-25; the average tube length of the carbon nanotubes being 1-20 μm, preferably 3-10 μm.

[0010] The second aspect of the present application provides a preparation method of a carbon nanotube-activated carbon composite material, comprising the following steps:

[0011] (1) mixing and reacting petroleum coke, an activating agent and a transition metal compound under contact condition, and obtaining material A after washing and drying the reaction product;

[0012] (2) mixing and treating material A obtained in step (1) with a polyol solution, and obtaining material B after separation, drying and calcination after the treatment is completed;

[0013] (3) mixing and reacting waste plastic and material B obtained in step (2) under contact condition, and obtaining the carbon nanotube-activated carbon composite material after washing and drying the reaction product.

[0014] Further preferably, in the above-mentioned preparation method of the carbon nanotube-activated carbon composite material, the waste plastic is any carbon chain-containing high molecular polymer, including but not limited to one or more of polyethylene, polypropylene, polyvinyl chloride, polystyrene, etc.

[0015] Further preferably, in the above-mentioned preparation method of the carbon nanotube-activated carbon composite material, the petroleum coke is solid coke generated by cracking and coking of residual oil in a coking device.

[0016] Further preferably, in the above-mentioned preparation method of the carbon nanotube-activated carbon composite material, the activating agent in step (1) can be selected from one or more of potassium hydroxide, calcium hydroxide, sodium hydroxide, potassium bicarbonate and potassium carbonate, and is preferably potassium hydroxide.

[0017] Further preferably, in the preparation method of the carbon nanotube-activated carbon composite material, the transition metal compound in step (1) can be selected from one or more of transition metal salts, transition metal oxides, and transition metal hydroxides; wherein the transition metal can be one or more of Fe, Co, Ni, Cu, Cr, Mo, and Pt; further, the transition metal compound can be specifically selected from one or more of iron nitrate, iron sulfate, iron chloride, iron phosphate, iron acetate, iron sesquioxide, iron hydroxide, nickel nitrate, nickel sulfate, nickel chloride, nickel phosphate, nickel acetate, nickel oxide, nickel hydroxide, cobalt nitrate, cobalt sulfate, cobalt chloride, cobalt phosphate, cobalt acetate, cobalt oxide, cobalt hydroxide, copper nitrate, copper sulfate, copper chloride, copper phosphate, copper acetate, copper oxide, copper hydroxide, chromium nitrate, chromium sulfate, chromium chloride, chromium phosphate, chromium acetate, chromium oxide, chromium hydroxide, molybdenum nitrate, molybdenum sulfate, molybdenum chloride, molybdenum phosphate, molybdenum acetate, molybdenum oxide, molybdenum hydroxide, platinum nitrate, platinum sulfate, platinum chloride, platinum phosphate, platinum acetate, platinum oxide, and platinum hydroxide; further preferably, one or more of iron nitrate, iron sulfate, iron chloride, nickel nitrate, nickel sulfate, nickel chloride, cobalt nitrate, and cobalt sulfate.

[0018] Further preferably, in the preparation method of the carbon nanotube-activated carbon composite material, the mass ratio of the petroleum coke, the activating agent, and the transition metal compound in step (1) is 1:0.2-8:0.01-1.5, and preferably 1:1-5:0.1-1.

[0019] Further preferably, in the preparation method of the carbon nanotube-activated carbon composite material, the reaction in step (1) is carried out in the presence of an inert atmosphere, which can be one or more of nitrogen, helium, neon, and argon, and is preferably nitrogen.

[0020] Further preferably, in the preparation method of the carbon nanotube-activated carbon composite material, the reaction temperature in step (1) is 500-1000°C, and is preferably 600-900°C.

[0021] Further preferably, in the preparation method of the carbon nanotube-activated carbon composite material, the reaction time in step (1) is 0.1-12h, and is preferably 0.3-5h.

[0022] Further preferably, in the preparation method of the carbon nanotube-activated carbon composite material, the washing in step (1) can be carried out by water washing, and the water washing is further specifically washing with water until the pH value of the filtrate is neutral.

[0023] Further preferably, in the preparation method of the carbon nanotube-activated carbon composite material, the drying in step (1) can be normal pressure drying or vacuum drying; the drying temperature is generally 50-250°C, and is preferably 60-150°C; and the drying time is 5-36h, and is preferably 8-24h.

[0024] Further preferably, in the preparation method of the carbon nanotube-activated carbon composite material, the polyol in step (2) is selected from polyhydric alcohols with 3 or more hydroxyl groups and C3-C7, and preferably one or both of glucose and xylitol.

[0025] Further preferably, in the preparation method of the carbon nanotube-activated carbon composite material, the treatment in step (2) is specifically as follows: material A is added to the polyol solution and stirred for 1-24 hours, preferably 4-10 hours, and then aged for 1-24 hours, preferably 2-8 hours. The mass ratio of material A to polyol is 1:0.001-0.05, preferably 1:0.01-0.04; and the mass concentration of the polyol solution is 0.05wt%-10wt%, preferably 0.5wt%-5wt%.

[0026] Further preferably, in the preparation method of the carbon nanotube-activated carbon composite material, the separation in step (2) is solid-liquid separation, and the specific separation means can be any means that can achieve liquid-solid separation in the art, such as at least one of filtration, centrifugal separation, and sedimentation separation.

[0027] Further preferably, in the preparation method of the carbon nanotube-activated carbon composite material, the drying temperature in step (2) is 60-150°C, preferably 80-130°C; and the drying time is 4-40 hours, preferably 6-24 hours.

[0028] Further preferably, in the preparation method of the carbon nanotube-activated carbon composite material, the calcination temperature in step (2) is 200-600°C, preferably 300-500°C, and the calcination time is 0.5-6 hours, preferably 1-4 hours. The calcination is carried out in an inert atmosphere, which can be one or more of nitrogen, helium, neon, argon, etc.; and preferably in a nitrogen atmosphere.

[0029] Further preferably, in the preparation method of the carbon nanotube-activated carbon composite material, the mass ratio of waste plastic to material B obtained in step (2) in step (3) is 1:0.1-10, preferably 1:0.2-8.

[0030] Further preferably, in the preparation method of the carbon nanotube-activated carbon composite material, the reaction in step (3) is carried out in the presence of an inert atmosphere, which can be one or more of nitrogen, helium, neon, argon, etc., and is preferably nitrogen.

[0031] Further preferably, in the preparation method of the carbon nanotube-activated carbon composite material, the reaction temperature in step (3) is 500-800°C, preferably 550-700°C.

[0032] Further preferably, in the preparation method of the carbon nanotube-activated carbon composite material, the reaction time in step (3) is 0.1-180 min, preferably 1-120 min.

[0033] Further preferably, in the preparation method of the carbon nanotube-activated carbon composite material, the reaction process in step (3) is carried out under microwave irradiation conditions, the microwave frequency is 2450 MHz or 915 MHz, and the microwave power is 0.1-10 kw per g of the mass of the reactants, preferably 0.5-5 kw.

[0034] Further preferably, in the preparation method of the carbon nanotube-activated carbon composite material, the washing in step (3) is carried out by first acid washing and then water washing. Generally, water washing refers to washing with water until the pH value of the filtrate is neutral. Further, acid washing is carried out by washing with an inorganic acid solution, and the inorganic acid can be one or more of hydrochloric acid, sulfuric acid, phosphoric acid and nitric acid, preferably one or more of hydrochloric acid, nitric acid and sulfuric acid. The concentration of the inorganic acid solution is 1-50 wt%, preferably 5-40 wt%. The acid washing temperature is 25-100℃, preferably 25-80℃, and the acid washing time is 0.5-10 h, preferably 1-6 h.

[0035] Further preferably, in the preparation method of the carbon nanotube-activated carbon composite material, the drying in step (3) can be atmospheric drying or vacuum drying. The drying temperature is 60-250℃, preferably 60-140℃, and the drying time is 2-36 h, preferably 3-24 h.

[0036] The third aspect of the present application provides a carbon nanotube-activated carbon composite material obtained by the above preparation method.

[0037] The fourth aspect of the present application provides an application of the above carbon nanotube-activated carbon composite material or the carbon nanotube-activated carbon composite material obtained by the above preparation method in a lithium ion battery negative electrode material or a supercapacitor carbon.

[0038] Compared with the prior art, the carbon nanotube-activated carbon composite material and the preparation method and application thereof have the following advantages:

[0039] 1. The present application provides a carbon nanotube-activated carbon composite material, which has a unique multi-level structure, both disordered porous structure and regular graphite structure, greatly improving the conductivity of the material compared with pure activated carbon material, and having smaller internal resistance. When used as a supercapacitor carbon, no additional conductive agent is needed, and the material has excellent electrochemical performance.

[0040] 2、The carbon nanotube-activated carbon composite material preparation method provided by the application uses cheap waste plastics and petroleum coke as raw materials, and provides a simple and low-cost carbon nanotube-activated carbon composite material preparation method, which greatly improves the resource utilization rate of waste plastics and petroleum coke.

[0041] 3、In the carbon nanotube-activated carbon composite material preparation method provided by the application, the metal-loaded activated carbon is treated with a polyol, so that a layer of carbon is deposited on the surface of the metal, which is beneficial to the immobilization and dispersion of the active metal, avoids the agglomeration of the metal in the subsequent reaction, and is not conducive to the growth of carbon nanotubes, and affects the quality of the carbon nanotubes; meanwhile, the deposited carbon can be used as a growth substrate for carbon nanotubes, and can effectively promote the growth of the subsequently introduced waste plastics into carbon nanotubes through microwave pyrolysis.

[0042] 4、In the carbon nanotube-activated carbon composite material preparation method provided by the application, a transition metal compound is introduced in the petroleum coke activation process to obtain activated carbon loaded with a transition metal, which has good wave absorption and is helpful to the rapid pyrolysis of waste plastics, thereby solving the problem that waste plastics cannot absorb microwaves under microwave conditions, and the advantage of fast microwave heating rate cannot be utilized; on the other hand, the activated carbon loaded with a transition metal can effectively catalyze the cracking of waste plastics to generate carbon nanotubes, and the carbon nanotube-activated carbon composite material is prepared.

[0043] 5、In the carbon nanotube-activated carbon composite material preparation method provided by the application, a transition metal compound is introduced in the in-situ activation process of petroleum coke, the activated agent is used to form pores to enter the diffusion path of the graphite crystallite layers and amorphous defects of the petroleum coke, and the transition metal enters the pore channel of the petroleum coke-based porous carbon together with the molten activated agent to form a high-dispersion structure loaded on the activated carbon, which has the advantages of high metal dispersion and good catalytic activity. BRIEF DESCRIPTION OF DRAWINGS

[0044] Figure 1 The TEM image (1 μm) of the carbon nanotube-activated carbon composite material prepared in Example 1 of the application.

[0045] Figure 2 The TEM image (20 nm) of the carbon nanotube-activated carbon composite material prepared in Example 1 of the application. DETAILED DESCRIPTION

[0046] The technical content and technical effects of the application will be further described in combination with specific embodiments, but the application is not limited by the embodiments.

[0047] In the examples and comparative examples of the present application, the specific surface area is measured by low temperature nitrogen physical adsorption method, and the instrument is an ASAP2460 physical adsorption instrument of Micromeritics Company. The test conditions are as follows: the sample is treated at 200°C for 5h under vacuum, and the test is carried out at liquid nitrogen temperature (-196°C). The adsorption-desorption isotherm is measured according to the static method, and the specific surface area of the catalyst is calculated according to the BET (Brunauer-Emmett-Teller) equation.

[0048] The thermogravimetric test is carried out on a STA449F5 synchronous thermal analyzer of NETZSCH Company. First, about 10mg of sample is added to an alumina crucible, the carrier gas (oxygen) flow rate is adjusted to 50mL / min, and the temperature is raised to the set temperature at a rate of 10°C / min. The weight loss curve is recorded, and then the temperature is lowered to room temperature (25°C). The weight loss ratio R of the composite material is calculated by the following formula: R=Δm1 / Δm2. Wherein Δm1 refers to the weight loss rate before 660°C in the thermogravimetric analysis under oxygen condition, and Δm2 refers to the weight loss rate after 660°C.

[0049] The electrochemical performance test of the composite material as the supercapacitor carbon is carried out as follows: the composite material and the binder polytetrafluoroethylene are mixed uniformly in a paste state according to a weight ratio of 9:1, then coated on a foamed nickel, pressed into a sheet by a tablet press, and dried at 60°C for 12h to prepare a composite material electrode sheet. The electrolyte is a 6mol / L potassium hydroxide solution, the test adopts a three-electrode system, the counter electrode is a Pt electrode, the reference electrode is a mercury-mercury electrode, and the composite material electrode sheet is the working electrode. The constant current charge and discharge test is carried out by using a Swiss Wintech Autolab electrochemical workstation, the test current is 1A / g, and the voltage is 0-1V. The specific capacitance of the composite material is calculated by the formula C=I·Δt / m·ΔV, wherein C is the specific capacitance of the electrode material, F / g; I is the discharge current, A; Δt is the discharge time, s; ΔV is the voltage difference, V; and m is the mass of the composite material, g.

[0050] Example 1

[0051] Petroleum coke, potassium hydroxide and nickel nitrate were mixed uniformly in a mass ratio of 1:3:0.37, and the mixture was reacted at 900°C under a nitrogen atmosphere for 1 h. After the product was cooled to room temperature, it was washed with water until the filtrate was neutral. The solid product was dried at 120°C for 12 h to obtain product A1. A xylitol solution (concentration of 1.5 wt%) was prepared, and product A1 and xylitol were added to the xylitol solution in a mass ratio of 1:0.03. After stirring for 2 h, the mixture was aged for 3 h, and the solid product was separated by filtration. The product was dried at 120°C for 12 h, and then calcined at 400°C under a nitrogen atmosphere for 3 h to obtain product B1. Waste plastic pipes crushed to a particle size of 20-300 mesh and product B1 were mixed uniformly in a mass ratio of 1:1, and the mixture was reacted at 580°C under a nitrogen atmosphere for 60 min by microwave irradiation. After the product was cooled to room temperature, it was washed with 5 wt% dilute hydrochloric acid at 40°C for 4 h. After filtration, the product was washed with water until the filtrate was neutral. The solid product was dried at 120°C for 12 h to obtain carbon nanotube-activated carbon composite material C-1. The material properties and evaluation results are shown in Table 1.

[0052] Example 2

[0053] Petroleum coke, potassium hydroxide and nickel nitrate were mixed uniformly in a mass ratio of 1:3:0.37, and the mixture was reacted at 900°C under a nitrogen atmosphere for 1 h. After the product was cooled to room temperature, it was washed with water until the filtrate was neutral. The solid product was dried at 120°C for 12 h to obtain product A1. A xylitol solution (concentration of 1.5 wt%) was prepared, and product A1 and xylitol were added to the xylitol solution in a mass ratio of 1:0.03. After stirring for 2 h, the mixture was aged for 3 h, and the solid product was separated by filtration. The product was dried at 120°C for 12 h, and then calcined at 400°C under a nitrogen atmosphere for 3 h to obtain product B1. Waste plastic pipes crushed to a particle size of 20-300 mesh and product B1 were mixed uniformly in a mass ratio of 1:1, and the mixture was reacted at 580°C under a nitrogen atmosphere for 60 min by microwave irradiation. After the product was cooled to room temperature, it was washed with 5 wt% dilute hydrochloric acid at 40°C for 4 h. After filtration, the product was washed with water until the filtrate was neutral. The solid product was dried at 120°C for 12 h to obtain carbon nanotube-activated carbon composite material C-1. The material properties and evaluation results are shown in Table 1.

[0054] Example 3

[0055] Petroleum coke crushed to a particle size of 20-300 mesh, potassium hydroxide and nickel nitrate were mixed uniformly in a mass ratio of 1:4:0.23, reacted at 850°C under a nitrogen atmosphere for 1 h, and the product was washed with water after being cooled to room temperature, filtered until the filtrate was neutral, and the solid product was dried at 130°C for 10 h to obtain product A3. A xylitol solution (concentration of 1.9 wt%) was prepared, product A3 and xylitol were added to the xylitol solution in a mass ratio of 1:0.035, stirred for 2 h, and then aged for 4 h, and the solid product was separated by filtration and dried at 110°C for 12 h. The product was calcined at 400°C under a nitrogen atmosphere for 4 h to obtain product B3. Waste plastic water pipes crushed to a particle size of 20-300 mesh and product B3 were mixed uniformly in a mass ratio of 1:1, reacted at 600°C under a nitrogen atmosphere for 50 min under microwave irradiation, and the product was washed with 5 wt% dilute hydrochloric acid at 25°C for 6 h after being cooled to room temperature. After filtration, the product was washed with water until the filtrate was neutral, and the solid product was dried at 110°C for 15 h to obtain carbon nanotube-activated carbon composite material C-3. The material properties and evaluation results are shown in Table 1.

[0056] Example 4

[0057] Petroleum coke crushed to a particle size of 20-300 mesh, potassium hydroxide and nickel nitrate were mixed uniformly in a mass ratio of 1:4:0.23, reacted at 850°C under a nitrogen atmosphere for 1 h, and the product was washed with water after being cooled to room temperature, filtered until the filtrate was neutral, and the solid product was dried at 130°C for 10 h to obtain product A3. A xylitol solution (concentration of 1.9 wt%) was prepared, product A3 and xylitol were added to the xylitol solution in a mass ratio of 1:0.035, stirred for 2 h, and then aged for 4 h, and the solid product was separated by filtration and dried at 110°C for 12 h. The product was calcined at 400°C under a nitrogen atmosphere for 4 h to obtain product B3. Waste plastic water pipes crushed to a particle size of 20-300 mesh and product B3 were mixed uniformly in a mass ratio of 1:1, reacted at 600°C under a nitrogen atmosphere for 50 min under microwave irradiation, and the product was washed with 5 wt% dilute hydrochloric acid at 25°C for 6 h after being cooled to room temperature. After filtration, the product was washed with water until the filtrate was neutral, and the solid product was dried at 110°C for 15 h to obtain carbon nanotube-activated carbon composite material C-3. The material properties and evaluation results are shown in Table 1.

[0058] Example 5

[0059] Petroleum coke, potassium hydroxide and ferric nitrate were mixed uniformly in a mass ratio of 1:3:0.52, and then reacted at 800°C under a nitrogen atmosphere for 1.5 h. After the product was cooled to room temperature, it was washed with water until the filtrate was neutral. The solid product was dried at 130°C for 10 h to obtain product A5. A glucose solution (concentration of 1.8 wt%) was prepared, and product A5 and glucose were added to the glucose solution in a mass ratio of 1:0.035. After stirring for 3 h, the mixture was aged for 5 h, and then the solid product was separated by filtration. The product was dried at 130°C for 8 h, and then calcined at 450°C under a nitrogen atmosphere for 3 h to obtain product B5. Waste plastic bottles and product B5 were mixed uniformly in a mass ratio of 1:1, and then reacted at 650°C under a nitrogen atmosphere for 80 min by microwave irradiation. After the product was cooled to room temperature, it was washed with 5 wt% dilute hydrochloric acid at 50°C for 4 h. After filtration, the product was washed with water until the filtrate was neutral. The solid product was dried at 110°C for 15 h to obtain carbon nanotube-activated carbon composite material C-5. The material properties and evaluation results are shown in Table 1.

[0060] Example 6

[0061] Petroleum coke, potassium hydroxide and ferric sulfate were mixed uniformly in a mass ratio of 1:3:0.32, and then reacted at 750°C under a nitrogen atmosphere for 2 h. After the product was cooled to room temperature, it was washed with water until the filtrate was neutral. The solid product was dried at 150°C for 8 h to obtain product A6. A xylitol solution (concentration of 2.0 wt%) was prepared, and product A6 and xylitol were added to the xylitol solution in a mass ratio of 1:0.04. After stirring for 3 h, the mixture was aged for 8 h, and then the solid product was separated by filtration. The product was dried at 130°C for 12 h, and then calcined at 400°C under a nitrogen atmosphere for 3 h to obtain product B6. Waste plastic pipes and product B6 were mixed uniformly in a mass ratio of 1:1, and then reacted at 600°C under a nitrogen atmosphere for 60 min by microwave irradiation. After the product was cooled to room temperature, it was washed with 15 wt% dilute hydrochloric acid at 40°C for 5 h. After filtration, the product was washed with water until the filtrate was neutral. The solid product was dried at 130°C for 10 h to obtain carbon nanotube-activated carbon composite material C-6. The material properties and evaluation results are shown in Table 1.

[0062] Example 7

[0063] Petroleum coke, potassium hydroxide and ferric nitrate were mixed uniformly in a mass ratio of 1:3:0.52, and then reacted at 800°C under a nitrogen atmosphere for 1 h. After the product was cooled to room temperature, it was washed with water until the filtrate was neutral. The solid product was dried at 120°C for 9 h to obtain product A7. A xylitol solution (2.0 wt%) was prepared, and product A7 and xylitol were added to the xylitol solution in a mass ratio of 1:0.04. After stirring for 2 h, the mixture was aged for 6 h, and then the solid product was separated by filtration. The product was dried at 130°C for 12 h, and then calcined at 420°C under a nitrogen atmosphere for 4 h to obtain product B7. Waste plastic and product B7 were mixed uniformly in a mass ratio of 1:1, and then reacted at 650°C under a nitrogen atmosphere for 70 min by microwave irradiation. After the product was cooled to room temperature, it was washed with 5 wt% dilute hydrochloric acid at 40°C for 6 h. After filtration, the product was washed with water until the filtrate was neutral. The solid product was dried at 120°C for 14 h to obtain carbon nanotube-activated carbon composite material C7. The material properties and evaluation results are shown in Table 1.

[0064] Comparative Example 1

[0065] Petroleum coke and potassium hydroxide were mixed uniformly in a mass ratio of 1:3, and then reacted at 800°C under a nitrogen atmosphere for 1 h. After the product was cooled to room temperature, it was washed with water until the filtrate was neutral. The solid product was dried at 120°C for 12 h to obtain product D-1. The material properties and evaluation results are shown in Table 1.

[0066] Comparative Example 2

[0067] Petroleum coke, potassium hydroxide and nickel nitrate were mixed uniformly in a mass ratio of 1:3:0.37, and then reacted at 900°C under a nitrogen atmosphere for 1 h. After the product was cooled to room temperature, it was washed with water until the filtrate was neutral. The solid product was dried at 120°C for 12 h to obtain product A’2. Waste plastic and product A’2 were mixed uniformly in a mass ratio of 1:1, and then reacted at 580°C under a nitrogen atmosphere for 60 min by microwave irradiation. After the product was cooled to room temperature, it was washed with 5 wt% dilute hydrochloric acid at 40°C for 4 h. After filtration, the product was washed with water until the filtrate was neutral. The solid product was dried at 120°C for 12 h to obtain carbon nanotube-activated carbon composite material D-2. The material properties and evaluation results are shown in Table 1.

[0068] Comparative Example 3

[0069] Petroleum coke, waste plastic pipe, potassium hydroxide and nickel nitrate were mixed uniformly in the mass ratio of 1:1:3:0.37, and then reacted under microwave radiation at 580°C in a nitrogen atmosphere for 60 min. After the product was cooled to room temperature, it was washed with 5 wt% dilute hydrochloric acid at 40°C for 4 h, and then filtered. The product was further washed with water until the filtrate was neutral. The solid product was dried at 120°C for 12 h to obtain carbon nanotube-activated carbon composite material D-3. The material properties and evaluation results are shown in Table 1.

[0070] Table 1 Material properties and evaluation results

[0071]

Claims

1. A carbon nanotube-activated carbon composite material, comprising carbon nanotubes and activated carbon, wherein the weight loss ratio R of the composite material is 0.5–20, and wherein the weight loss ratio R is calculated by the following formula: R = Δm1 / Δm2, where Δm1 refers to the weight loss rate before 660℃ under oxygen conditions according to thermogravimetric analysis, and Δm2 refers to the weight loss rate after 660℃; the preparation method of the carbon nanotube-activated carbon composite material includes the following steps: (1) Under contact conditions, petroleum coke, activator and transition metal compound are mixed and reacted. The reaction product is washed and dried to obtain material A. (2) The material A obtained in step (1) is mixed with a polyol solution and then separated, dried and calcined to obtain material B. (3) Under contact conditions, waste plastic and material B obtained in step (2) are mixed and reacted. The reaction product is washed and dried to obtain carbon nanotube-activated carbon composite material.

2. The carbon nanotube-activated carbon composite material according to claim 1, wherein, The weight loss ratio R of the composite material is 1 to 10.

3. The carbon nanotube-activated carbon composite material according to claim 1, wherein, The specific surface area of ​​the composite material is 800–2500 m². 2 / g.

4. The carbon nanotube-activated carbon composite material according to claim 1, wherein, The specific surface area of ​​the composite material is 1000–2000 m². 2 / g.

5. The carbon nanotube-activated carbon composite material according to claim 1, wherein, The carbon nanotubes are multi-walled carbon nanotubes, with an average wall number of 10–40; the average tube length of the carbon nanotubes is 1–20 μm.

6. The carbon nanotube-activated carbon composite material according to claim 1, wherein, The carbon nanotubes are multi-walled carbon nanotubes, with an average wall number of 15–25; the average tube length of the carbon nanotubes is 3–10 μm.

7. A method for preparing a carbon nanotube-activated carbon composite material, comprising the following steps: (1) Under contact conditions, petroleum coke, activator and transition metal compound are mixed and reacted. The reaction product is washed and dried to obtain material A. (2) The material A obtained in step (1) is mixed with a polyol solution and then separated, dried and calcined to obtain material B. (3) Under contact conditions, waste plastic and material B obtained in step (2) are mixed and reacted. The reaction product is washed and dried to obtain carbon nanotube-activated carbon composite material.

8. The method for preparing the carbon nanotube-activated carbon composite material according to claim 7, wherein, Waste plastics are any high molecular polymers containing carbon chains, including one or more of polyethylene, polypropylene, polyvinyl chloride, and polystyrene.

9. The method for preparing the carbon nanotube-activated carbon composite material according to claim 7, wherein, In step (1), the activator is selected from one or more of potassium hydroxide, calcium hydroxide, sodium hydroxide, potassium bicarbonate, and potassium carbonate.

10. The method for preparing the carbon nanotube-activated carbon composite material according to claim 7, wherein, The activator in step (1) is potassium hydroxide.

11. The method for preparing the carbon nanotube-activated carbon composite material according to claim 7, wherein, In step (1), the transition metal compound is selected from one or more of transition metal salts, transition metal oxides, and transition metal hydroxides; wherein the transition metal is one or more of Fe, Co, Ni, Cu, Cr, Mo, and Pt.

12. The method for preparing the carbon nanotube-activated carbon composite material according to claim 7, wherein, In step (1), the transition metal compound is selected from one or more of the following: ferric nitrate, ferric sulfate, ferric chloride, ferric phosphate, ferric acetate, ferric oxide, ferric hydroxide, nickel nitrate, nickel sulfate, nickel chloride, nickel phosphate, nickel acetate, nickel oxide, nickel hydroxide, cobalt nitrate, cobalt sulfate, cobalt chloride, cobalt phosphate, cobalt acetate, cobalt oxide, cobalt hydroxide, copper nitrate, copper sulfate, copper chloride, copper phosphate, copper acetate, copper oxide, copper hydroxide, chromium nitrate, chromium sulfate, chromium chloride, chromium phosphate, chromium acetate, chromium oxide, chromium hydroxide, molybdenum nitrate, molybdenum sulfate, molybdenum chloride, molybdenum phosphate, molybdenum acetate, molybdenum oxide, molybdenum hydroxide, platinum nitrate, platinum sulfate, platinum chloride, platinum phosphate, platinum acetate, platinum oxide, and platinum hydroxide.

13. The method for preparing the carbon nanotube-activated carbon composite material according to claim 7, wherein, In step (1), the transition metal compound is selected from one or more of the following: ferric nitrate, ferric sulfate, ferric chloride, nickel nitrate, nickel sulfate, nickel chloride, cobalt nitrate, and cobalt sulfate.

14. The method for preparing the carbon nanotube-activated carbon composite material according to claim 7, wherein, In step (1), the mass ratio of petroleum coke, activator, and transition metal compound is 1:0.2-8:0.01-1.

5.

15. The method for preparing the carbon nanotube-activated carbon composite material according to claim 7, wherein, In step (1), the mass ratio of petroleum coke, activator, and transition metal compound is 1:1 to 5:0.1 to 1.

16. The method for preparing the carbon nanotube-activated carbon composite material according to claim 7, wherein, The reaction in step (1) is carried out in the presence of an inert atmosphere, which is one or more of nitrogen, helium, neon and argon.

17. The method for preparing the carbon nanotube-activated carbon composite material according to claim 7, wherein, The reaction in step (1) is carried out in the presence of an inert atmosphere, which is nitrogen.

18. The method for preparing the carbon nanotube-activated carbon composite material according to claim 7, wherein, The reaction temperature in step (1) is 500-1000℃.

19. The method for preparing the carbon nanotube-activated carbon composite material according to claim 7, wherein, The reaction temperature in step (1) is 600-900℃.

20. The method for preparing the carbon nanotube-activated carbon composite material according to claim 7, wherein, In step (1), the drying temperature is 50-250℃ and the drying time is 5-36h.

21. The method for preparing the carbon nanotube-activated carbon composite material according to claim 7, wherein, In step (1), the drying temperature is 60-150℃ and the drying time is 8-24h.

22. The method for preparing the carbon nanotube-activated carbon composite material according to claim 7, wherein, The polyols mentioned in step (2) are selected from C3 to C7 polyols containing three or more hydroxyl groups.

23. The method for preparing the carbon nanotube-activated carbon composite material according to claim 7 or 22, wherein, The polyol mentioned in step (2) is one or both of glucose and xylitol.

24. The method for preparing the carbon nanotube-activated carbon composite material according to claim 7, wherein, The processing procedure described in step (2) is as follows: add material A into a polyol solution and stir for 1 to 24 hours, then let it stand and age for 1 to 24 hours.

25. The method for preparing the carbon nanotube-activated carbon composite material according to claim 7, wherein, The processing procedure described in step (2) is as follows: add material A into a polyol solution and stir for 4 to 10 hours, then let it stand for aging for 2 to 8 hours.

26. The method for preparing the carbon nanotube-activated carbon composite material according to claim 24 or 25, wherein, The mass ratio of material A to polyol is 1:0.001 to 0.05; the mass concentration of the polyol solution is 0.05wt% to 10wt%.

27. The method for preparing the carbon nanotube-activated carbon composite material according to claim 24 or 25, wherein, The mass ratio of material A to polyol is 1:0.01 to 0.04; the mass concentration of the polyol solution is 0.5wt% to 5wt%.

28. The method for preparing the carbon nanotube-activated carbon composite material according to claim 7, wherein, The drying temperature in step (2) is 60-150℃ and the drying time is 4-40h.

29. The method for preparing the carbon nanotube-activated carbon composite material according to claim 7, wherein, The drying temperature in step (2) is 80-130℃ and the drying time is 6-24h.

30. The method for preparing the carbon nanotube-activated carbon composite material according to claim 7, wherein, The calcination temperature in step (2) is 200-600℃, and the calcination time is 0.5-6h. The calcination is carried out under an inert atmosphere.

31. The method for preparing the carbon nanotube-activated carbon composite material according to claim 7, wherein, The roasting temperature in step (2) is 300-500℃ and the roasting time is 1-4h. The roasting is carried out under an inert atmosphere.

32. The method for preparing the carbon nanotube-activated carbon composite material according to claim 7, wherein, In step (3), the mass ratio of waste plastic to material B obtained in step (2) is 1:0.1~10.

33. The method for preparing the carbon nanotube-activated carbon composite material according to claim 7, wherein, In step (3), the mass ratio of waste plastic to material B obtained in step (2) is 1:0.2~8.

34. The method for preparing the carbon nanotube-activated carbon composite material according to claim 7, wherein, The reaction in step (3) is carried out in the presence of an inert atmosphere, which is one or more of nitrogen, helium, neon and argon.

35. The method for preparing the carbon nanotube-activated carbon composite material according to claim 7, wherein, The reaction in step (3) is carried out in the presence of an inert atmosphere, which is nitrogen.

36. The method for preparing the carbon nanotube-activated carbon composite material according to claim 7, wherein, The reaction temperature in step (3) is 500-800℃.

37. The method for preparing the carbon nanotube-activated carbon composite material according to claim 7, wherein, The reaction temperature in step (3) is 550–700℃.

38. The method for preparing the carbon nanotube-activated carbon composite material according to claim 7, wherein, The reaction process in step (3) is carried out under microwave radiation conditions, with a microwave frequency of 2450MHz or 915MHz and a microwave power of 0.1 to 10kw per gram of reactant mass.

39. The method for preparing the carbon nanotube-activated carbon composite material according to claim 7, wherein, The reaction process in step (3) is carried out under microwave radiation conditions, with a microwave frequency of 2450MHz or 915MHz and a microwave power of 0.5 to 5kw per gram of reactant mass.

40. The method for preparing the carbon nanotube-activated carbon composite material according to claim 7, wherein, In step (3), the washing process involves acid washing followed by water washing.

41. The method for preparing the carbon nanotube-activated carbon composite material according to claim 7, wherein, In step (3), the drying temperature is 60-250℃ and the drying time is 2-36 h.

42. The method for preparing the carbon nanotube-activated carbon composite material according to claim 7, wherein, In step (3), the drying temperature is 60-140℃ and the drying time is 3-24 h.

43. A carbon nanotube-activated carbon composite material obtained by the preparation method according to any one of claims 7-42.

44. The application of a carbon nanotube-activated carbon composite material according to any one of claims 1-6 or a carbon nanotube-activated carbon composite material obtained by the preparation method according to any one of claims 7-42 in lithium-ion battery anode materials and supercapacitor carbon.

Images