Carbon fiber aggregate, preparation method and application thereof, and method for preparing synthesis gas by using carbon dioxide

Abstract

The invention relates to the technical field of new material preparation, and discloses a carbon fiber aggregate, a preparation method and application thereof, and a method for preparing synthesis gas by using carbon dioxide. The carbon fiber aggregate comprises a plurality of carbon fiber basic units which are arranged in a non-directional manner, and each carbon fiber basic unit is a carbon fiber bundle formed by a single carbon fiber and / or a plurality of carbon fibers; the two ends of each carbon fiber in the length direction are carbon fiber tail ends, and the number of the carbon fiber tail ends contained in each gram of the carbon fiber aggregate is more than 1 * 10 < 6 > / g according to the number of the carbon fiber tail ends. Although the carbon fiber aggregate is pure carbon fiber, the carbon fiber aggregate can generate plasma and high temperature of over 1000 DEG C under microwave irradiation.

Description

Technical Field

[0001] The present invention relates to the technical field of new material preparation, and in particular to a carbon fiber aggregate, a preparation method and application thereof, and a method for preparing synthesis gas by utilizing carbon dioxide. Background Art

[0002] Extreme climate and energy crisis are two major challenges that mankind needs to face in this century. As we all know, carbon dioxide is the main greenhouse gas, and the occurrence of global extreme climate is mainly affected by the increase in global carbon dioxide emissions. Therefore, the treatment of carbon dioxide has become an issue that the whole society needs to pay attention to and solve. The utilization of carbon dioxide can be divided into four categories: chemical synthesis, fuel production, biological application and direct application. At present, the total annual carbon dioxide emissions in the world are about 35 billion tons / year. However, the total carbon dioxide consumption in the chemical industry, which uses the most carbon dioxide, is only about 220 million tons / year, which is a drop in the bucket compared to the total global carbon dioxide emissions. Therefore, only by converting carbon dioxide into energy fuel can the use of carbon dioxide match the consumption of carbon dioxide. Among the current methods of converting carbon dioxide into energy fuel, the technology of converting carbon dioxide and water into synthesis gas is the most concerned. The reason is that synthesis gas is a traditional fuel energy, water resources are easy to obtain, and synthesis gas is also an important chemical energy storage medium.

[0003] Plasma is the fourth state of matter besides solid, liquid and gas. Its characteristic is that the plasma state is highly dependent on the electromagnetic field. The material composition of plasma is unbound ions and free electrons, and the overall state of plasma is electrically neutral. Microwave refers to electromagnetic waves with a wavelength between infrared and ultra-high frequency (UHF) radio waves, which have very strong penetrating ability. Its wavelength is between 1m and 1mm, and the corresponding frequency is 300GHz-300MHz. Microwave plasma technology is a technology that generates plasma by microwave irradiation, which can achieve an energy conversion efficiency of more than 60% under the condition of plasma non-equilibrium state. Microwave plasma has a significant thermal effect. The porous composite materials prepared in Chinese invention patent application CN111099917A and Chinese invention patent application CN112823441A can generate a high temperature of more than 1000℃ by microwave irradiation under an inert atmosphere. However, the porous composite materials prepared in Chinese invention patent application CN111099917A and Chinese invention patent application CN112823441A are rigid structural materials, which are brittle and easy to damage, and are not conducive to long-term use.

[0004] Therefore, how to provide a new type of material that can generate a high temperature of more than 1000°C in a microwave and which can overcome the problem of large brittleness and easy damage of existing porous composite materials is the research direction of the present invention. Summary of the invention

[0005] Carbon fiber is a material that has both high strength and flexibility. Ordinary carbon fiber, such as T300 carbon fiber monofilament, has a tensile strength of up to 3500MPa and a tensile modulus of up to 230GPa. From a physical property point of view, although it can solve the problem of high brittleness and easy damage, since carbon fiber can both absorb and reflect microwaves, and weaving carbon fiber will only produce microwave reflective materials, such practical applications show that carbon fiber is more inclined to reflect microwaves. At present, there is no precedent for pure carbon fiber to generate plasma through microwave irradiation as a microwave heating material. Through research, the inventors of the present invention unexpectedly found that by controlling the number of carbon fiber ends contained in each gram of the carbon fiber aggregate, a carbon fiber aggregate can be obtained. Although the carbon fiber aggregate is pure carbon fiber, it can generate plasma and a high temperature of more than 1000°C under microwave irradiation.

[0006] Based on the above findings, the object of the present invention is to provide a fiber assembly and a preparation method and application thereof, as well as a method for preparing synthesis gas using carbon dioxide.

[0007] A first aspect of the present invention is a carbon fiber aggregate, the carbon fiber aggregate comprising a plurality of randomly arranged carbon fiber basic units, the carbon fiber basic units being a single carbon fiber and / or a carbon fiber bundle formed by a plurality of carbon fibers;

[0008] The two ends of each carbon fiber in the length direction are the carbon fiber ends, and the number of carbon fiber ends contained in each gram of the carbon fiber aggregate is 1×10 6 Pieces / g or more.

[0009] In a preferred embodiment of the present invention, the carbon fiber aggregate presents a two-dimensional or three-dimensional spatial structure.

[0010] In a preferred embodiment of the present invention, at least part of two or more adjacent carbon fiber basis units are in contact with each other; preferably, the contact includes at least one of abutting, overlapping and interlacing with each other.

[0011] In a preferred embodiment of the present invention, the number of carbon fiber ends contained in each gram of the carbon fiber aggregate is 1×10 6 ~6×10 8 / g, preferably 1×10 6 ~6×10 7 pcs / g, more preferably 1×10 6 ~2×10 7 Pieces / g.

[0012] In a preferred embodiment of the present invention, the carbon fiber bundle is a carbon fiber bundle filament fixed together; at least one fixed node is provided on the carbon fiber bundle filament; more preferably,

[0013] When there is only one fixed node on the carbon fiber bundle, the length of the carbon fiber bundle is 0.1 to 30 mm, preferably 1 to 20 mm, and more preferably 3 to 20 mm;

[0014] When more than two fixing nodes are provided on the carbon fiber bundle, the spacing between adjacent fixing nodes is 1 to 50 mm, preferably 2 to 30 mm, more preferably 5 to 20 mm; and part of the carbon fiber bundle between adjacent fixing nodes is in a disconnected state.

[0015] In a preferred embodiment of the present invention, the fixing includes bundling fixing and / or knotting fixing, and the fixing nodes include bundling nodes and / or knotting points. More preferably, the knotting fixing is that the carbon fiber bundles are fixed by knotting themselves; and / or the bundles of the bundling fixing are carbon fiber bundles.

[0016] The raw materials used for the carbon fiber aggregate described in the present invention can be purchased on the market. According to the present invention, the carbon fiber bundles can adopt various types of carbon fiber bundles in the prior art. In a preferred embodiment of the present invention, the carbon fiber bundles, the carbon fiber bundles for bundling, and the carbon fiber bundles for knotting are independently selected from at least one of the following types of carbon fiber bundles: T300, T700, T800, T1000, T1100, M40, M50, M60; preferably selected from at least one of the following types of carbon fiber bundles: T300, T700, T800; more preferably selected from at least one of the following types of carbon fiber bundles: T300, T700.

[0017] According to the present invention, there are multiple options for the number of carbon fibers contained in each bundle of carbon fiber bundles. In a preferred embodiment of the present invention, the number of carbon fibers contained in each bundle of carbon fiber bundles is 1K-48K, preferably 1K, 3K, 6K, 12K, 24K, 48K; more preferably 12K, 24K, and most preferably 12K.

[0018] According to the present invention, the carbon fiber assembly comprises a plurality of carbon fiber basic units arranged in an irregular manner, and the carbon fiber basic unit is a carbon fiber bundle formed by a single carbon fiber and / or a plurality of carbon fibers. In a preferred embodiment of the present invention, the carbon fiber basic unit is a carbon fiber bundle formed by a plurality of carbon fibers, or the carbon fiber basic unit comprises both a single carbon fiber and a carbon fiber bundle, or the carbon fiber basic unit is a single carbon fiber. More preferably, the carbon fiber basic unit is a carbon fiber bundle formed by a plurality of carbon fibers, or the carbon fiber basic unit comprises both a single carbon fiber and a carbon fiber bundle. In this more preferred embodiment, the carbon fiber assembly is easier to use and recycle.

[0019] In a more preferred embodiment of the present invention, when the carbon fiber basic unit contains both a single carbon fiber and a carbon fiber bundle, the total mass of the carbon fiber aggregate is 100wt%, and the content of the carbon fiber bundle in the carbon fiber aggregate is 0.1-99.9wt%, preferably 1-99wt%; and / or, the length of each fiber of the single carbon fiber is 0.1-30mm, preferably 1-20mm, more preferably 3-20mm; and / or, the diameter of the single carbon fiber is 5-10μm, and / or, the density is 1.5-2.0g / cm 3 .

[0020] The second aspect of the present invention is to provide a method for preparing the carbon fiber aggregate according to the first aspect, comprising:

[0021] The single carbon fibers and / or carbon fiber bundles are assembled in a non-directional arrangement to obtain the carbon fiber aggregate; wherein the method for preparing the carbon fiber bundles includes fixing the carbon fiber bundles together and providing at least one fixed node on the carbon fiber bundles, and when more than two fixed nodes are provided on the carbon fiber bundles, the carbon fiber bundles between adjacent fixed nodes are partially disconnected or completely disconnected.

[0022] The described collection refers to gathering scattered carbon fiber basic units together, which are physically mixed rather than chemically connected to each other; for example, the collection of carbon fiber basic units is achieved by adopting a stacking aggregation method or a winding aggregation method, and then preferably at least partially achieving contact between two or more adjacent carbon fiber basic units, and more preferably, at least partially achieving contact between two or more adjacent carbon fiber basic units in at least one manner including abutment, overlap, interlacing, etc.

[0023] In a preferred embodiment of the present invention, the fixing includes bundling and / or knotting.

[0024] In a preferred embodiment of the present invention, the disconnection includes cutting and / or shearing.

[0025] In a more preferred embodiment of the present invention, when there is only one fixed node on the carbon fiber bundle, the length of the carbon fiber bundle is 0.1-30 mm, preferably 1-20 mm, and more preferably 3-20 mm.

[0026] In a more preferred embodiment of the present invention, when there are more than two fixed nodes on the carbon fiber bundle, the spacing between adjacent fixed nodes is 1-50 mm, preferably 2-30 mm, and more preferably 5-20 mm.

[0027] The fixing includes bundling fixing and / or knotting fixing, and the fixing nodes include bundling nodes and / or knotting points. Preferably, the knotting fixing is performed by knotting the carbon fiber bundle itself; and / or, the bundling fixing adopts the carbon fiber bundle for bundling; more preferably, the knotting method is at least one of a single knot, a flat knot, a Bollinger knot, an Alpine bow knot, an Alpine bow knot, a double Alpine bow knot, a Blake knot, a clove knot, an 8-shaped single knot, and an 8-shaped connecting knot; for the knotting method, preferably at least one of a single knot, a flat knot, an Alpine bow knot, an Alpine bow knot, a double Alpine bow knot, an 8-shaped single knot, and an 8-shaped connecting knot; more preferably, at least one of a single knot, a flat knot, an Alpine bow knot, and an 8-shaped single knot.

[0028] The equipment used in the preparation method of the present invention is all commonly used equipment.

[0029] The above-mentioned method for preparing the carbon fiber aggregate directly uses high-strength carbon fiber as raw material. Through simple processing, a flexible, high-temperature resistant material that can generate a high temperature of more than 1000°C in a microwave field can be prepared. The process flow is simple and easy to implement, and large-scale preparation is easy.

[0030] The third aspect of the present invention is to provide a material for microwave irradiation heating, comprising the carbon fiber aggregate according to the first aspect or the carbon fiber aggregate prepared by the preparation method according to the second aspect; preferably,

[0031] Under microwave irradiation of 300 W or more, the temperature of the material for microwave irradiation heating can reach above 1000° C.

[0032] The oxygen-free atmosphere includes a reaction gas that does not contain oxygen and an optional protective atmosphere. The protective atmosphere includes, but is not limited to, nitrogen and / or an inert gas. The reaction gas is, for example, pure carbon dioxide, or a mixed gas of carbon dioxide and water vapor.

[0033] The fourth aspect of the present invention is to provide a use of the carbon fiber aggregate described in the first aspect or the carbon fiber aggregate prepared by the preparation method described in the second aspect as a heating material in a microwave field under microwave irradiation; preferably,

[0034] The power of the microwave irradiation is greater than 300 W, preferably 300-2000 W, more preferably 500-1500 W, further preferably 700-1200 W; and / or, and / or, the microwave irradiation is carried out in an atmosphere free of oxygen.

[0035] The fifth aspect of the present invention is to provide an application of the carbon fiber aggregate described in the first aspect or the carbon fiber aggregate prepared by the preparation method described in the second aspect in a microwave field, including microwave heating to crack organic matter and preparing synthesis gas using carbon dioxide under a microwave field; preferably, the organic matter includes one or more of plastics, biomass, and organic volatiles.

[0036] The sixth aspect of the present invention is to provide a method for preparing synthesis gas using carbon dioxide, comprising: in a microwave field, in the presence of the carbon fiber aggregate described in the first aspect, the carbon fiber aggregate prepared by the preparation method described in the second aspect, or the material for microwave irradiation heating described in the third aspect:

[0037] Reaction 1: contacting the carbon fiber aggregate, carbon dioxide and graphite to react and obtain carbon monoxide; or,

[0038] Reaction 2 is carried out, wherein the carbon fiber aggregate, carbon dioxide, water vapor and graphite are contacted to react to obtain carbon monoxide and hydrogen.

[0039] The present invention utilizes the thermal effect and catalytic effect of plasma generated by microwave irradiation of carbon fiber aggregates in a carbon dioxide atmosphere, and can convert recycled carbon materials (such as graphite recovered from discarded lithium batteries) into carbon monoxide and hydrogen by reacting with carbon dioxide and water vapor to prepare synthesis gas, thereby playing the role of converting and utilizing carbon dioxide while processing discarded carbon materials.

[0040] In a preferred embodiment of the present invention, in reaction 1:

[0041] The mass ratio of the carbon fiber aggregate to the graphite is (100:1) to (1:100), preferably (20:1) to (1:20), and more preferably (10:1) to (1:10); and / or,

[0042] The microwave power is greater than 300 W, preferably 300-2000 W, more preferably 500-1500 W, further preferably 700-1200 W; and / or the microwave time is 0.1 to 200 min, preferably 0.5 to 150 min, most preferably 1 to 100 min.

[0043] In a preferred embodiment of the present invention, in reaction 2:

[0044] The mass ratio of the carbon fiber aggregate to the graphite is (100:1) to (1:100), preferably (1:1) to (1:20), and more preferably (1:1) to (1:10); and / or,

[0045] The volume ratio of carbon dioxide to water vapor is (99.9:0.1) to (10:90), and more preferably (98:2) to (20:80); and / or,

[0046] The microwave power is greater than 300 W, preferably 300-2000 W, more preferably 500-1500 W, further preferably 700-1200 W; and / or the microwave time is 0.1 to 200 min, preferably 0.5 to 150 min, most preferably 1 to 100 min.

[0047] According to a preferred embodiment of the present invention, the method for preparing synthesis gas using carbon dioxide comprises the following steps:

[0048] a. placing the carbon fiber aggregate and graphite in a sealable reaction container, wherein the reaction container is made of a microwave transparent material;

[0049] b. introducing carbon dioxide into the reaction vessel, or introducing a mixture of carbon dioxide and water vapor into the reactor;

[0050] c. Start the microwave, place the reaction container under the microwave field to react, obtain gas products, and collect the gas products;

[0051] Preferably,

[0052] The graphite is from waste graphite, more preferably from graphite recovered from discarded lithium batteries; and / or,

[0053] The microwave irradiation atmosphere may optionally contain nitrogen and / or an inert gas. Preferably, the inert gas is selected from argon.

[0054] According to the present invention, a microwave-transparent reaction vessel refers to a reaction vessel through which microwaves can penetrate the wall of the reaction vessel and radiate to the sample. The reaction vessel can be made of various containers or pipes made of materials that are microwave-transparent and resistant to high temperatures above 1000°C (such as quartz, alumina, boron nitride) in the prior art.

[0055] The microwave field in the method of the present invention can adopt various microwave equipment in the prior art, such as household microwave ovens, industrial microwave equipment (such as microwave thermal cracking reactors), etc.

[0056] The gas product collection method is a common method in the prior art, preferably carried out under an inert atmosphere. For example, if a microwave oven is used as a microwave field, the gas collection method is as follows: in a glove box protected by nitrogen, a quartz crucible carrying waste plastics and porous composite materials is placed in a vacuum bag and sealed, and after the reaction under microwave, the crucible is unscrewed through the vacuum bag, and a syringe is used to pierce the vacuum bag for sampling; an industrial microwave oven with an air inlet and an air outlet (such as a microwave thermal cracking reactor, etc.) is used, and the gas collection method is as follows: nitrogen is purged during the reaction process, and a gas collection bag is used to sample and collect at the air outlet.

[0057] Through the above technical scheme, the present invention provides a carbon fiber aggregate, a preparation method and application, and a method for preparing synthesis gas using carbon dioxide. The carbon fiber aggregate is a material composed of a large number of carbon fiber ends gathered in a disordered manner, wherein plasma can be generated between the carbon fiber ends under microwave irradiation. The present invention obtains a carbon fiber aggregate by controlling the number of carbon fiber ends contained in each gram of the carbon fiber aggregate. Although the carbon fiber aggregate is pure carbon fiber, it can generate plasma and a high temperature of more than 1000°C under microwave irradiation. It overcomes the problem of high brittleness and easy damage of porous composite materials in the prior art. Not only that, the carbon fiber aggregate of the present invention has simple raw materials, is easy to prepare, and has extremely high promotion and application value.

[0058] Carbon monoxide and hydrogen are important chemical raw materials. By adopting the method for preparing synthesis gas of the present invention and using a carbon fiber aggregate as a carbon fiber microwave heating material, carbon dioxide can be effectively converted into carbon monoxide, or carbon dioxide and water can be converted into carbon monoxide and hydrogen, thereby realizing resource utilization of carbon dioxide and recycling graphite in discarded batteries, which has extremely high application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0059] Figure 1 This is a morphological photograph of the carbon fiber aggregate in Example 1 of the present invention; wherein the carbon fiber basic unit is a carbon fiber bundle prepared from carbon fiber bundle filaments;

[0060] Figure 2 This is a morphological photograph of the carbon fiber aggregate in Example 2 of the present invention; wherein the carbon fiber basic unit is a single carbon fiber;

[0061] Figure 3 This is a morphological photograph of the carbon fiber aggregate in Example 5 of the present invention, wherein the carbon fiber basic unit includes both a single carbon fiber and a carbon fiber bundle. DETAILED DESCRIPTION

[0062] The present invention is described in detail below in conjunction with specific embodiments. It is necessary to point out that the following embodiments are only used to further illustrate the present invention and cannot be understood as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made to the present invention by those skilled in the art based on the contents of the present invention still fall within the scope of protection of the present invention.

[0063] The experimental data in the examples were measured using the following instruments and measurement methods:

[0064] In the embodiment, the collected synthesis gas components are subjected to chromatographic analysis in the following manner:

[0065] The gas products collected after cracking were analyzed using a refinery gas analyzer (HPAgilent 7890A, equipped with 3 channels, including 1 FID and 2 TCDs (thermal conductivity detectors)) according to the ASTM D1945-14 method. Hydrocarbons were analyzed on the FID channel. A TCD using nitrogen as carrier gas was used to determine the hydrogen content because there is a small difference in the conductivity of hydrogen and helium carrier gases. Another TCD using helium as carrier gas was used to detect CO, CO 2 、N 2 and O 2 For quantitative analysis, the response factors were determined by using RGA (Refinery Gas Analysis) calibration gas standards.

[0066] The number of carbon fiber ends contained in each gram of the carbon fiber aggregate is obtained by theoretical calculation, and the specific calculation method is:

[0067] (1) When the carbon fiber basic unit of the carbon fiber aggregate is a single carbon fiber, the number of carbon fiber ends contained in each gram of the carbon fiber aggregate corresponds to the following formula:

[0068]

[0069] N is the number of carbon fiber ends contained in each gram of the carbon fiber aggregate (unit: pieces / g), and ρ is the carbon fiber density (unit: g / cm 3 ), d is the carbon fiber diameter (unit: μm), and L is the carbon fiber filament length (unit: mm).

[0070] (2) When the carbon fiber basic unit of the carbon fiber aggregate is a carbon fiber bundle prepared from carbon fiber bundles having one or more knotting points, the number of carbon fiber ends contained in each gram of the carbon fiber aggregate is calculated as follows:

[0071] N=[(n-1)×2×t+2]×k / m

[0072] N is the number of carbon fiber ends contained in each gram of the carbon fiber aggregate (unit: pieces / g), n is the number of knotting points on the carbon fiber bundle; t is the proportion of long carbon fiber bundles cut between the knotting points, k is the number of carbon fiber roots in the carbon fiber bundle, and m is the total mass of the carbon fiber bundle (unit: g).

[0073] Take the calculation method described in Example 1 as an example. A 5000mm long T300 carbon fiber 12K bundle is tied with itself at a knotting interval of 10mm (single knot), and 499 knots can be tied. Cutting the carbon fiber at the middle position of the two ends of the knotting point by two-thirds can produce [(499-1)×2×2 / 3+2)]×12000=7992000 carbon fiber ends. The knotting point formed by the single knot is a ring without an end. The mass of the 5000mm long T300 carbon fiber 12K bundle is 3.96g. Therefore, the number of carbon fiber ends contained in each gram of the carbon fiber aggregate described in Example 1 is 7992000÷3.96g≈2×10 6 Pieces / g.

[0074] (3) For a carbon fiber aggregate prepared from carbon fiber bundles having one or more fixed nodes and / or bundled nodes, the number of carbon fiber ends contained in each gram of the carbon fiber aggregate is calculated as follows:

[0075] N=[(n-1)×2×t×k+2k+c 1 ×n 1 ×k 1 )] / m

[0076] N is the number of carbon fiber ends contained in each gram of the carbon fiber aggregate (unit: pieces / g), n is the total number of fixed nodes formed by knotting and bundling on the carbon fiber bundle; t is the proportion of the long carbon fiber bundle cut at the fixed node, and k is the number of carbon fibers in the long carbon fiber bundle;

[0077] c 1 When the fixed node is a bundling node, the number of ends of each bundle at each fixed node; n 1 is the number of bundled nodes; k 1 It is the number of carbon fibers contained in the carbon fiber bundles in the bundle of the bundled node.

[0078] m is the total mass of the carbon fiber bundle (unit: g).

[0079] (4) When the carbon fiber basic unit of the carbon fiber aggregate includes both a single carbon fiber and a carbon fiber bundle, the number of carbon fiber ends contained in each gram of the carbon fiber aggregate is calculated as follows:

[0080]

[0081] N is the number of carbon fiber ends contained in each gram of the carbon fiber aggregate (unit: pieces / g), n is the total number of fixed nodes formed by knotting and bundling on the carbon fiber bundles in the part constructed with the carbon fiber bundles as the basic unit in the carbon fiber aggregate; t is the proportion of the long carbon fiber bundles at the fixed nodes cut in the part constructed with the carbon fiber bundles as the basic unit in the carbon fiber aggregate, k is the number of carbon fibers in the long carbon fiber bundles in the part constructed with the carbon fiber bundles as the basic unit in the carbon fiber aggregate; c 1 The number of ends of each bundle at each fixed node in the part of the carbon fiber assembly constructed with carbon fiber bundles as the basic unit when the fixed node is a bundle node; n 1 k is the number of bundled nodes in the carbon fiber aggregate constructed with carbon fiber bundles as the basic unit; 1 is the number of carbon fibers containing carbon fiber bundles in the bundle of the bundled nodes in the part constructed with carbon fiber bundles as the basic unit in the carbon fiber aggregate; ρ is the carbon fiber density in the part constructed with a single carbon fiber as the basic unit in the carbon fiber aggregate (unit: g / cm 3 ), d is the diameter of the carbon fiber in the part constructed with a single carbon fiber as the basic unit in the carbon fiber aggregate (unit: μm), L is the length of the carbon fiber in the part constructed with a single carbon fiber as the basic unit in the carbon fiber aggregate (unit: mm); m 1 is the total mass of the carbon fiber aggregate constructed with carbon fiber bundles as the basic unit (unit: g), m 2 It is the total mass of the part constructed with a single carbon fiber as the basic unit in the carbon fiber aggregate (unit: g).

[0082] Take the calculation method described in Example 5 as an example. A 2500mm long T300 carbon fiber 12K bundle is knotted by itself with a knotting spacing of 10mm (single knot), and 249 knots can be tied. Cutting two-thirds of the carbon fiber bundle at a distance of 5mm between the knotting points can produce [(249-1)×2×2 / 3+2)]×12000=3992000 carbon fiber ends. The knotting point formed by the single knot is a ring without an end. The mass of the 2500mm long T300 carbon fiber 12K bundle is 1.98g; the length is 5mm, the diameter is 7μm, and the density is 1.8g / cm 3 , the mass of a single T700 carbon fiber is 3 g, so the number of carbon fiber ends contained in each gram of the carbon fiber aggregate described in Example 5 is.

[0083]

[0084] Temperature detection method: After the microwave irradiation is completed, a metal thermocouple is immediately inserted into the reaction container and brought into contact with the carbon fiber aggregate to measure the temperature.

[0085] Example 1

[0086] Take a 5000mm long T300 carbon fiber 12K bundle (3.96g, Weihai Guangwei Composite Materials Group Co., Ltd.), use a single knotting method, according to the knotting spacing of 10mm, to tie 499 knots. Cut two-thirds of the carbon fiber bundle at 5mm between the knotting points to make a carbon fiber aggregate. The material is rolled up and placed in a quartz jar. The number of carbon fiber ends contained in each gram of carbon fiber aggregate is about 2×10 6 At this time, the material can generate plasma and an equilibrium temperature of 1200°C under pure carbon dioxide atmosphere by 900W microwave irradiation.

[0087] Comparative Example 1

[0088] Take a 5000mm long T300 carbon fiber 12K bundle (3.96g, Weihai Guangwei Composite Materials Group Co., Ltd.), use a single knotting method, according to the knotting spacing of 250mm, to tie 19 knots. Cut two-thirds of the carbon fiber bundle at 125mm between the knotting points to make a carbon fiber aggregate, roll it up and put it in a quartz jar. The number of carbon fiber ends contained in each gram of carbon fiber aggregate is about 7.9×10 4 At this time, the material was irradiated with 900W microwaves in a pure carbon dioxide atmosphere, and the material equilibrium temperature could only reach 300°C.

[0089] Example 2

[0090] Take 4g of a single T300 carbon fiber (short carbon fiber, density 1.76g / cm) with a length of 3mm and a diameter of 7μm. 3 , Weihai Guangwei Composite Materials Group Co., Ltd.), randomly stacked in a quartz jar, and the number of carbon fiber ends contained in each gram of carbon fiber aggregate is about 9.8×10 6 At this time, the material can generate plasma and an equilibrium temperature of 1400°C under pure carbon dioxide atmosphere by 1200W microwave irradiation.

[0091] Comparative Example 2

[0092] Take 4g of a single T300 carbon fiber (short carbon fiber, density 1.76g / cm) with a length of 60mm and a diameter of 7μm. 3 , Weihai Guangwei Composite Materials Group Co., Ltd.), randomly stacked in a quartz jar, and the number of carbon fiber ends per gram of carbon fiber aggregate is about 4.9×10 5 At this time, the material was irradiated with 1200W microwaves in a pure carbon dioxide atmosphere, and the material temperature could only reach an equilibrium temperature of 600°C.

[0093] Example 3

[0094] Take a 5600mm long T700 carbon fiber 12K bundle (4.48g, diameter 7μm, Weihai Guangwei Composite Materials Group Co., Ltd.), use a single knotting method, according to the knotting spacing of 14mm, to tie 399 knots. Cut two-thirds of the carbon fiber bundle at 7mm from the middle of the knotting point to make a carbon fiber aggregate. The material is rolled up and placed in a quartz jar. The number of carbon fiber ends contained in each gram of carbon fiber aggregate is about 1.4×10 6 At this time, the material can generate plasma and an equilibrium temperature of 1100°C by 700W microwave irradiation in a mixed gas atmosphere of carbon dioxide and water vapor with a volume ratio of 90:10.

[0095] Comparative Example 3

[0096] Take a 5000mm long T700 carbon fiber 12K bundle (4.0g, Weihai Guangwei Composite Materials Group Co., Ltd.), use a single knotting method, according to the knotting spacing of 250mm, and tie 19 knots. Cut two-thirds of the carbon fiber bundle at 125mm between the knotting points to make a carbon fiber aggregate, roll it up and put it in a quartz jar. The number of carbon fiber ends contained in each gram of carbon fiber aggregate is about 7.8×10 4 At this time, the material was irradiated with 700W microwaves in a mixed gas atmosphere of carbon dioxide and water vapor with a volume ratio of 90:10, and the material equilibrium temperature could only reach 100°C.

[0097] Example 4

[0098] Take 6g of T700 single carbon fiber (short carbon fiber, density 1.8g / cm) with a length of 5mm and a diameter of 7μm 3 , Weihai Guangwei Composite Materials Group Co., Ltd.), randomly stacked in a quartz jar, and the number of carbon fiber ends per gram of carbon fiber aggregate is about 5.8×10 6 At this time, the material can generate plasma and an equilibrium temperature of 1050°C by 1200W microwave irradiation in a mixed gas atmosphere of carbon dioxide and water vapor with a volume ratio of 30:70.

[0099] Comparative Example 4

[0100] Take 6g of T700 single carbon fiber (short carbon fiber, density 1.8g / cm) with a length of 35mm and a diameter of 7μm 3 , Weihai Guangwei Composite Materials Group Co., Ltd.), randomly stacked in a quartz jar, and the number of carbon fiber ends per gram of carbon fiber aggregate is about 8.3×10 5At this time, the material was irradiated with 1200W microwave in a mixed gas atmosphere with a volume ratio of carbon dioxide and water vapor of 30:70, and the material equilibrium temperature could only reach 900℃.

[0101] Example 5

[0102] Take a 2500mm long T300 carbon fiber 12K bundle (1.98g, Weihai Guangwei Composite Materials Group Co., Ltd.), use a single knotting method, according to the knotting spacing of 10mm, to tie 249 knots. Cut two-thirds of the carbon fiber bundle at 5mm between the knotting points; take 3g of a single T700 carbon fiber (short carbon fiber, density 1.8g / cm 3 , Weihai Guangwei Composite Materials Group Co., Ltd.), mixed with knotted carbon fiber bundles to form carbon fiber aggregates, which were randomly stacked in a quartz tank. The number of carbon fiber ends per gram of carbon fiber aggregate per unit mass was about 4.3×10 6 At this time, the material can generate plasma and an equilibrium temperature of 1280°C under pure carbon dioxide atmosphere by 900W microwave irradiation.

[0103] The carbon fiber aggregates prepared in Examples 1-5 have a number of carbon fiber ends greater than 1×10 6 / g, sufficient plasma can be generated under microwave irradiation in pure carbon dioxide and mixed gas (carbon dioxide and water vapor) atmosphere, so that the material equilibrium temperature is greater than 1000°C. The carbon fiber aggregates prepared in Comparative Examples 1-4 have a carbon fiber end number per gram of carbon fiber aggregate less than 1×10 6 / g, and sufficient plasma cannot be generated under microwave irradiation in the atmosphere of pure carbon dioxide and mixed gas (carbon dioxide and water vapor), so that the material equilibrium temperature is less than 900℃.

[0104] An embodiment of applying a carbon fiber aggregate to prepare synthesis gas from carbon dioxide.

[0105] Example 6

[0106] The carbon fiber aggregate (4 g) prepared in Example 1 was mixed with graphite (2 g) from discarded batteries and placed in a quartz jar. The mixture was irradiated with microwaves at a microwave power of 900 W for 20 minutes under a pure carbon dioxide atmosphere. The graphite was completely consumed and the collected gas products are shown in Table 1.

[0107] Example 7

[0108] The carbon fiber aggregate (4 g) prepared in Example 2 was mixed with graphite (2 g) from discarded batteries and placed in a quartz jar. The mixture was irradiated with microwaves at a microwave power of 700 W for 20 minutes under a pure carbon dioxide atmosphere. The graphite was completely consumed and the collected gas products are shown in Table 1.

[0109] Example 8

[0110] The carbon fiber aggregate (4 g) prepared in Example 1 was mixed with graphite (40 g) from discarded batteries and placed in a quartz jar. The mixture was irradiated with microwaves at a microwave power of 900 W for 20 minutes under a pure carbon dioxide atmosphere. The graphite was completely consumed and the collected gas products are shown in Table 1.

[0111] Example 9

[0112] The carbon fiber aggregate (8 g) prepared in Example 3 and the graphite (2 g) from the discarded battery were placed in a quartz jar and irradiated with microwaves at a microwave power of 1200 W for 20 minutes in a mixed gas atmosphere of carbon dioxide and water vapor in a volume ratio of 90:10. The graphite was completely consumed and the collected gas products are shown in Table 1.

[0113] Example 10

[0114] The carbon fiber aggregate (6 g) prepared in Example 4 and the graphite (2 g) from the discarded battery were placed in a quartz jar and irradiated with microwaves at a microwave power of 1200 W for 20 minutes in a mixed gas atmosphere of carbon dioxide and water vapor in a volume ratio of 30:70. The graphite was completely consumed and the collected gas products are shown in Table 1.

[0115] Embodiment 11

[0116] The carbon fiber aggregate (8 g) prepared in Example 3 and the graphite (64 g) from the discarded battery were placed in a quartz jar and irradiated with microwaves at a microwave power of 1200 W for 20 minutes in a mixed gas atmosphere of carbon dioxide and water vapor in a volume ratio of 90:10. The graphite was completely consumed and the collected gas products are shown in Table 1.

[0117] Comparative Example 5

[0118] Graphite (2 g) from discarded batteries was placed in a quartz jar and irradiated with microwaves at a microwave power of 900 W for 20 minutes in a pure carbon dioxide atmosphere. The mass of the graphite did not change, and the collected gas products are shown in Table 1.

[0119] Comparative Example 6

[0120] Graphite (2 g) from discarded batteries was placed in a quartz jar and irradiated with microwaves at a microwave power of 1200 W for 20 minutes in a mixed gas atmosphere of carbon dioxide and water vapor in a volume ratio of 30:70. The mass of the graphite did not change, and the collected gas products are shown in Table 1.

[0121] Table 1

[0122] Serial number Carbon dioxide / vol% Carbon monoxide / vol% Hydrogen / vol% Example 6 1.7 98.3 0 Example 7 1.5 98.5 0 Example 8 4.6 95.4 0 Example 9 1.2 74.1 24.7 Example 10 2.3 50.9 46.8 Embodiment 11 3.2 73.4 23.4 Comparative Example 5 0 100 0 Comparative Example 6 0 100 0

[0123] Examples 6-8 confirm that the graphite and carbon fiber aggregates in the waste battery are subjected to microwave irradiation in a pure carbon dioxide atmosphere, which can make the graphite and carbon dioxide react and convert into carbon monoxide efficiently. Examples 9-11 confirm that the graphite and carbon fiber aggregates in the waste battery are subjected to microwave irradiation in a mixed gas atmosphere of carbon dioxide and water vapor, which can make the graphite and carbon dioxide and water vapor react and convert into carbon monoxide and hydrogen efficiently.

[0124] Compared with Example 6, when the carbon fiber aggregate is removed, the gas phase product collected after microwave treatment does not contain carbon monoxide, indicating that the use of the carbon fiber aggregate is the key to the reaction of carbon dioxide and graphite to generate carbon monoxide.

[0125] Compared with Example 10, when the carbon fiber aggregate is removed, the gas phase product collected after microwave treatment does not contain carbon monoxide and hydrogen. This shows that the use of the carbon fiber aggregate is the key to the reaction of the mixed gas of carbon dioxide and water vapor with graphite to generate carbon monoxide. Carbon monoxide and hydrogen are synthesis gas, which is also an important chemical raw material, indicating that the carbon fiber aggregate can effectively convert carbon dioxide into synthesis gas and realize the resource utilization of carbon dioxide.

[0126] It should be noted that the embodiments described above are only used to explain the present invention and do not constitute any limitation to the present invention. The present invention has been described with reference to typical embodiments, but it should be understood that the words used therein are descriptive and explanatory words, rather than restrictive words. The present invention may be modified as specified within the scope of the claims of the present invention, and the present invention may be revised without departing from the scope and spirit of the present invention. Although the present invention described therein relates to specific methods, materials and embodiments, it does not mean that the present invention is limited to the specific examples disclosed therein, on the contrary, the present invention can be extended to all other methods and applications with the same functions.

[0127] All publications, patent applications, patents and other references mentioned in this specification are incorporated herein by reference. Unless otherwise defined, all technical and scientific terms used in this specification have the meanings conventionally understood by those skilled in the art. In the event of a conflict, the definition in this specification shall prevail.

[0128] When this specification uses the prefix "well-known to those skilled in the art", "prior art" or similar terms to introduce materials, substances, methods, steps, devices or components, etc., the objects introduced by the prefix cover those commonly used in the art when this application is filed, but also include those that are not commonly used at present but will become recognized in the art as being suitable for similar purposes.

[0129] The endpoints and any values ​​of the scope disclosed in the present application document are not limited to the precise scope or value, and these scopes or values ​​should be understood to include values ​​close to these scopes or values. For numerical ranges, between the endpoint values ​​of each scope, between the endpoint values ​​of each scope and a separate point value, and between separate point values, one or more new numerical ranges can be combined with each other, and these numerical ranges should be considered as specifically disclosed in this article. Hereinafter, in principle, each technical solution can be combined with each other to obtain a new technical solution, which should also be considered as specifically disclosed in this article.

[0130] In the context of the present specification, any matters or items not mentioned are directly applicable to those known in the art without any changes except those explicitly stated.

[0131] Moreover, any embodiment described in this document may be freely combined with one or more other embodiments described in this document, and the technical solutions or technical ideas formed thereby are deemed to be part of the original disclosure or original record of the present invention, and should not be regarded as new content that has not been disclosed or anticipated in this document, unless a person skilled in the art considers that the combination is obviously unreasonable.

Claims

1. A carbon fiber aggregate, comprising a plurality of randomly arranged carbon fiber basic units, wherein the carbon fiber basic unit is a single carbon fiber and / or a carbon fiber bundle formed by a plurality of carbon fibers; The two ends of each carbon fiber in the length direction are the carbon fiber ends, and the number of carbon fiber ends contained in each gram of the carbon fiber aggregate is 1×10 6 Pieces / g or more.

2. The carbon fiber aggregate according to claim 1, characterized in that: The carbon fiber aggregate presents a two-dimensional or three-dimensional spatial structure; and / or, At least some of two or more adjacent carbon fiber base units are in contact with each other; and / or, Calculated by the number of carbon fiber ends, the number of carbon fiber ends contained in each gram of the carbon fiber aggregate is 1×10 6 ~6×10 8 / g, preferably 1×10 6 ~6×10 7 pcs / g, more preferably 1×10 6 ~2×10 7 Pieces / g.

3. The carbon fiber aggregate according to claim 1, characterized in that: The carbon fiber bundle is a carbon fiber bundle filament fixed together; at least one fixed node is provided on the carbon fiber bundle filament; preferably, When there is only one fixed node on the carbon fiber bundle, the length of the carbon fiber bundle is 0.1 to 30 mm, preferably 1 to 20 mm, and more preferably 3 to 20 mm; When the carbon fiber bundle is provided with more than two fixed nodes, the spacing between adjacent fixed nodes is 1 to 50 mm, preferably 2 to 30 mm, more preferably 5 to 20 mm; and part of the carbon fiber bundle between adjacent fixed nodes is disconnected; and / or, The fixing includes bundling fixing and / or knotting fixing, and the fixing nodes include bundling nodes and / or knotting points. More preferably, the knotting fixing is that the carbon fiber bundles are fixed by knotting themselves; and / or the bundles of the bundling fixing are carbon fiber bundles.

4. The carbon fiber aggregate according to claim 3, characterized in that: The carbon fiber bundles, the carbon fiber bundles for bundling, and the carbon fiber bundles for knotting are independently selected from at least one of the following types of carbon fiber bundles: T300, T700, T800, T1000, T1100, M40, M50, and M60; preferably selected from at least one of the following types of carbon fiber bundles: T300, T700, and T800; more preferably selected from at least one of the following types of carbon fiber bundles: T300 and T700.

5. The carbon fiber aggregate according to claim 4, characterized in that: The number of carbon fibers contained in each bundle of carbon fiber filaments is 1K-48K, preferably 1K, 3K, 6K, 12K, 24K, 48K; more preferably 12K, 24K.

6. The carbon fiber aggregate according to any one of claims 1 to 5, characterized in that: The carbon fiber basic unit is a carbon fiber bundle formed by multiple carbon fibers, or the carbon fiber basic unit contains both a single carbon fiber and a carbon fiber bundle, or the carbon fiber basic unit is a single carbon fiber; preferably, When the carbon fiber basic unit comprises both a single carbon fiber and a carbon fiber bundle, the content of the carbon fiber bundle in the carbon fiber aggregate is 0.1-99.9wt%, preferably 1-99wt%, based on the total mass of the carbon fiber aggregate being 100wt%; and / or The length of each single carbon fiber is 0.1-30 mm, preferably 1-20 mm, and more preferably 3-20 mm.

7. A method for preparing a carbon fiber aggregate according to any one of claims 1 to 6, comprising: The single carbon fibers and / or carbon fiber bundles are assembled in a non-directional arrangement to obtain the carbon fiber aggregate; wherein the method for preparing the carbon fiber bundles includes fixing the carbon fiber bundles together and providing at least one fixed node on the carbon fiber bundles, and when more than two fixed nodes are provided on the carbon fiber bundles, the carbon fiber bundles between adjacent fixed nodes are partially disconnected or completely disconnected.

8. The preparation method according to claim 6, characterized in that: The fixing includes tying and / or knotting; and / or, The disconnection includes cutting and / or shearing; preferably, When a fixed node is provided on the carbon fiber bundle, the length of the carbon fiber bundle is 0.1-30 mm, preferably 1-20 mm, more preferably 3-20 mm; and / or, When the carbon fiber bundle is provided with two or more fixed nodes, the spacing between adjacent fixed nodes is 1-50 mm, preferably 2-30 mm, more preferably 5-20 mm; and / or, The fixing nodes include bundling nodes and / or knotting points. Preferably, the knotting and fixing are performed by knotting the carbon fiber bundles themselves; and / or the bundling and fixing are performed by bundling the carbon fiber bundles.

9. A material for microwave irradiation heating, comprising the carbon fiber aggregate according to any one of claims 1 to 6 or the carbon fiber aggregate prepared by the preparation method according to any one of claims 7 to 8; preferably, Under microwave irradiation of 300 W or more, the temperature of the material for microwave irradiation heating can reach above 1000° C.

10. Use of the carbon fiber aggregate according to any one of claims 1 to 6 or the carbon fiber aggregate prepared by the preparation method according to any one of claims 7 to 8 as a heating material in a microwave field under microwave irradiation; preferably, The power of the microwave irradiation is greater than 300 W, preferably 300-2000 W, more preferably 500-1500 W, further preferably 700-1200 W; and / or, The microwave irradiation is performed in an atmosphere free of oxygen.

11. An application of the carbon fiber aggregate described in any one of claims 1 to 6 or the carbon fiber aggregate prepared by the preparation method described in any one of claims 7 to 8 in a microwave field, comprising microwave heating to crack organic matter and preparing synthesis gas using carbon dioxide under a microwave field; preferably, the organic matter includes one or more of plastics, biomass, and organic volatiles.

12. A method for preparing synthesis gas using carbon dioxide, comprising: in a microwave field, in the presence of the carbon fiber aggregate according to any one of claims 1 to 6, the carbon fiber aggregate prepared by the preparation method according to any one of claims 7 to 8, or the material for microwave irradiation heating according to claim 9: Reaction 1: contacting the carbon fiber aggregate, carbon dioxide and graphite to react and obtain carbon monoxide; or, Reaction 2 is carried out, wherein the carbon fiber aggregate, carbon dioxide, water vapor and graphite are contacted to react to obtain carbon monoxide and hydrogen.

13. The method according to claim 12, characterized in that: Reaction 1: The mass ratio of the carbon fiber aggregate to the graphite is (100:1) to (1:100), preferably (20:1) to (1:20), and more preferably (10:1) to (1:10); and / or, The microwave power is greater than 300 W, preferably 300-2000 W, more preferably 500-1500 W, further preferably 700-1200 W; and / or, The microwave time is 0.1 to 200 min, preferably 0.5 to 150 min, most preferably 1 to 100 min.

14. The method according to claim 12, characterized in that: Reaction 2: The mass ratio of the carbon fiber aggregate to the graphite is (100:1) to (1:100), preferably (1:1) to (1:20), and more preferably (1:1) to (1:10); and / or, The volume ratio of carbon dioxide to water vapor is (99.9:0.1) to (10:90), and more preferably (98:2) to (20:80); and / or, The microwave power is greater than 300 W, preferably 300-2000 W, more preferably 500-1500 W, further preferably 700-1200 W; and / or, The microwave time is 0.1 to 200 min, preferably 0.5 to 150 min, most preferably 1 to 100 min.

15. The method according to any one of claims 12 to 14, characterized in that The following steps are involved: a. placing the carbon fiber aggregate and graphite in a sealable reaction container so that they are in contact with each other, and the material of the reaction container is a microwave transparent material; b. introducing carbon dioxide into the reaction vessel, or introducing a mixture of carbon dioxide and water vapor into the reactor; c. Start the microwave, place the reaction container under the microwave field to react, obtain gas products, and collect the gas products; Preferably, The graphite is from waste graphite, more preferably from graphite recovered from discarded lithium batteries; and / or, The microwave irradiation atmosphere may also contain nitrogen and / or an inert gas.

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