CARBON FIBER ASSEMBLIES, METHODS OF MANUFACTURING, AND THEIR USE

Abstract

The invention relates to a carbon fiber amalgam, a method of fabrication, and the use of such an amalgam. The amalgam consists of a number of carbon fiber basic units arranged in an unoriented manner, wherein the carbon fiber basic unit is a bundle of carbon fibers formed by multiple carbon fibers and arbitrary single carbon fibers; the bundle of carbon fibers is a bundle of carbon fibers fixed together; at least one fixing knot is arranged on the bundle of carbon fibers; taking the two ends of each carbon fiber in the length direction as the carbon fiber ends, the number of carbon fiber ends in each gram of the amalgam is greater than or equal to 1 × 10⁶ considering the number of carbon fiber ends. The amalgam can be used for the microwave heating of organic materials, and for the synthesis of carbon dioxide using carbon dioxide in a microwave field; the organic materials include one or more of the following: resins, biomass, and volatile organic compounds.

Description

Carbon fiber aggregate, preparation method and application Technical Field

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

[0002] Extreme climate change and energy crises are two major challenges facing humanity this century. As we all know, carbon dioxide is a major greenhouse gas, and global extreme climate change is primarily driven by rising global carbon dioxide emissions. Therefore, the disposal of carbon dioxide has become a problem that requires the attention and resolution of all of society. Carbon dioxide utilization can be categorized into four major categories: chemical synthesis, fuel production, biological applications, and direct applications. Currently, global carbon dioxide emissions total approximately 35 billion tons per year. However, the chemical industry, the largest user of carbon dioxide, only uses approximately 220 million tons per year, a drop in the bucket compared to global carbon dioxide emissions. Therefore, only by converting carbon dioxide into energy and fuel can carbon dioxide use be matched with consumption. Among the current methods for converting carbon dioxide into energy and fuel, the technology that reacts carbon dioxide with water to produce syngas is attracting the most attention. This is because syngas is a traditional fuel energy source, water resources are readily available, and syngas is also an important chemical energy storage medium.

[0003] Over 90% of chemical raw materials come from fossil fuels such as petroleum, shale gas, and coal. The current shortage of fossil energy and the environmental problems associated with fossil fuel use have made the development of environmentally friendly renewable energy a hot topic in the current energy sector. For more sustainable economic and social development, there is an urgent need to replace fossil energy with renewable biomass energy. Straw is a common agricultural solid waste in rural my country, characterized by its widespread distribution and abundant resources. According to the United Nations Environment Programme (UNEP), various cereal crops grown worldwide provide 1.7 billion tons of straw annually, and my country's total crop straw production reaches over 700 million tons, making it a significant renewable energy resource. The rapid development of pyrolysis technology in recent years has made it one of the more efficient and mature technologies for biomass utilization. However, numerous studies have found that biomass contains a large amount of aromatic hydrocarbons and aromatic derivatives. These substances, when heated, form large amounts of tar and coke, requiring extensive cleaning of reaction vessels. If the tar in the cracking products is not treated, it will gradually cool as it is carried through pipelines, forming a viscous liquid that adheres to the pipelines, causing corrosion, scaling, blockage, and other safety threats to pipelines and equipment.

[0004] Polyolefins refer to thermoplastic polymers formed by polymerizing ethylene, propylene, butene, or α-olefins. These include polyethylene (PE), polypropylene (PP), and ethylene-vinyl acetate copolymer (EVA), which are commonly used in daily life. Currently, global polyolefin production exceeds 220 million tons per year. They are widely used in healthcare, agriculture, transportation, electronics, construction, energy conservation, environmental protection, and new energy, making them the world's largest and most widely used polymer material. my country is the world's largest producer and consumer of polyolefins, with total production capacity reaching 53 million tons per year and total consumption exceeding 66 million tons per year in 2020. However, due to the carbon-carbon bonds in the polyolefin backbone, they are chemically stable, making them difficult to degrade in the wild and even in strong acid and alkaline conditions. This makes waste polyolefins a significant source of environmental pollution, often referred to as white pollution. Although polyolefins can be recycled through thermoplastic processing, the addition and use of additives during the recycling process prevents them from being permanently recycled through physical recycling. Ultimately, chemical recycling methods are needed to process polyolefins into chemical feedstocks or fuels. Pyrolysis is the most effective method for processing waste polyolefins, but the process is prone to forming tar and carbon deposits. This reduces the heat transfer efficiency of the cracking furnace. If the tar in the cracking products is not treated, it will gradually cool as it is carried through pipelines, forming a viscous liquid that adheres to the pipes, causing corrosion, scaling, blockage, and other safety threats to pipelines and equipment.

[0005] VOCs (volatile organic compounds) are a class of organic compounds with boiling points between 50 and 260°C at standard atmospheric pressure. They primarily originate from refineries, the chemical industry, fuel combustion, pharmaceutical plants, the automotive industry, textile manufacturers, solvent processing, cleaning products, printing presses, insulation materials, and office supplies. VOCs are toxic and carcinogenic, not only damaging the environment but also reacting with other atmospheric pollutants (such as NOx and SOx) to form photochemical smog, which in turn depletes the ozone layer. Long-term exposure to VOCs poses a threat to human health and can cause irreversible damage. With the acceleration of industrialization, annual VOC emissions have increased dramatically. According to statistics, VOC emissions in 2019 were approximately 23.4 Tg. If current control levels remain unchanged, due to rapid economic development, total anthropogenic VOC emissions in my country are projected to increase by 23% by 2025 compared to 2019. To reduce the harmful effects of VOCs on the environment and humans, my country has implemented strict regulations to limit further VOC emissions. These regulations include requirements for monitoring, controlling, and treating VOCs emission sources. In addition, VOCs treatment technology is also an important way to eliminate pollution and has attracted widespread attention.

[0006] At present, the VOCs composition in the industrial production process is extremely complex. According to the survey, the main hydrocarbon VOCs components are: 2-methylpentane, hydrogen, n-hexane, 2,2,4-trimethylpentane, n-heptane, 2,3,4-trimethylpentane, methylcyclohexane, n-octane, n-nonane, n-decane, propane, isobutane, isobutylene, n-butane, cyclopentane, isopentane, n-pentane, ethane, n-undecane, n-dodecane, methylcyclopentane, 3-methylpentane, 3-methylhexane, 2-methylhexane, 2,4-dimethylpentane, 2,2-dimethylbutane, 2,3 -Dimethylbutane, cyclohexane, 2-methylheptane, 3-methylheptane, 2,3-dimethylpentane, propylene, trans-2-butene, 1-butene, cis-2-butene, 1-pentene, cis-2-pentene, ethylene, acetylene, benzene, ethylbenzene, o-xylene, m-xylene, p-xylene, methane, toluene, m-ethyltoluene, p-ethyltoluene, o-ethyltoluene, styrene, isopropylbenzene, n-propylbenzene, 1,3,5-trimethylbenzene, 1,2,4-trimethylbenzene, 1,2,3-trimethylbenzene, m-diethylbenzene, p-diethylbenzene, acetone, 1,3-butadiene, carbon monoxide, etc.

[0007] Although these VOCs contain many chemical raw materials, their complex composition makes it difficult for petrochemical companies to effectively utilize them through gas separation. Therefore, petrochemical companies currently primarily use combustion to treat VOCs. This involves adding combustible gases to the VOCs and then fully burning them. However, this method has a significant drawback: combustion produces carbon dioxide. Carbon dioxide is a greenhouse gas that absorbs heat from the Earth's surface and gradually raises the temperature, contributing to global warming. Therefore, when petrochemical companies use combustion to treat VOCs, they increase their carbon emissions, adversely affecting global climate change. Furthermore, petrochemical companies also emit carbon dioxide during their production processes. These emissions primarily come from oil processing, petrochemical production, and energy consumption. Therefore, to reduce carbon dioxide emissions, we seek to develop a technology that can simultaneously treat both VOCs and carbon dioxide.

[0008] Plasma is the fourth state of matter, in addition to solid, liquid, and gas. Its characteristic is that its state is highly dependent on electromagnetic fields. Plasma is composed of unbound ions and free electrons, and its overall state is electrically neutral. Microwaves are electromagnetic waves with a wavelength between infrared and ultra-high frequency (UHF) radio waves, possessing very strong penetrating power. Their wavelengths range from 1 meter to 1 mm, corresponding to frequencies of 300 GHz to 300 MHz. Microwave plasma technology, which generates plasma through microwave irradiation, can achieve energy conversion efficiencies exceeding 60% under non-equilibrium plasma conditions.

[0009] Microwave plasma has a significant thermal effect. Chinese invention patent applications CN111099917A and CN112823441A describe porous composite materials produced by microwave irradiation in an inert atmosphere, generating temperatures exceeding 1000°C. However, the porous composite materials produced in these applications are rigid structural materials, resulting in high brittleness and easy damage, making them unsuitable for long-term use.

[0010] China's invention patent CN111099943A uses a porous composite material to generate a high temperature of over 1000°C under a nitrogen atmosphere through microwave irradiation, thereby rapidly cracking biomass. However, the porous composite materials prepared by these two patents are rigid structural materials, which are brittle and easily damaged, making them unsuitable for long-term use. They also cannot solve the problem of generating a large amount of tar and coke when cracking biomass.

[0011] Chinese invention patent CN111100661A, the porous composite material prepared can generate a high temperature of more than 1000 ° C by microwave irradiation in a nitrogen atmosphere, thereby quickly cracking polyolefins. However, the porous composite materials prepared by these two patents are rigid structural materials, which are brittle and easy to damage, which is not conducive to long-term use, and cannot solve the problem that polyolefin cracking produces a large amount of tar and coke. Studies have found that carbon dioxide can react with coke and tar under high microwave temperatures to convert into carbon monoxide. Therefore, if a microwave heating material that is not easily damaged and can generate plasma in a microwave field containing a carbon dioxide atmosphere is designed and synthesized, that is, the coke and tar produced by biomass cracking are reduced, the utilization rate of biomass microwave cracking is improved, and carbon dioxide is recycled and utilized at the same time, achieving efficient recycling of carbon dioxide and biomass, it has a wide range of application markets.

[0012] Furthermore, research has found that carbon dioxide can react with coke and tar under microwave temperatures to convert into carbon monoxide. Therefore, if a durable microwave heating material capable of generating plasma in a microwave field containing a carbon dioxide atmosphere could be designed and synthesized, it would be possible to reduce the coke and tar produced by polyolefin cracking, improve the utilization rate of polyolefin microwave cracking, and simultaneously recycle carbon dioxide, achieving efficient simultaneous recycling of carbon dioxide and polyolefins, potentially having broad market applications.

[0013] Furthermore, research has found that VOCs can be cracked into methane, ethylene, hydrogen, and amorphous carbon under microwave plasma at temperatures exceeding 1000°C. Amorphous carbon, at 1000°C, can react with carbon dioxide to produce carbon monoxide. Methane, carbon monoxide, and hydrogen are important energy fuels. Ethylene can be used to produce polyethylene, and hydrogen and carbon monoxide can be used to produce alkanes through Fischer-Tropsch synthesis. Therefore, the technology of simultaneously converting VOCs and carbon dioxide into methane, ethylene, carbon monoxide, and hydrogen has extremely high economic value and market applications.

[0014] Therefore, the research direction of this invention is to provide a new material that can generate high temperatures exceeding 1000°C in microwaves, and which can overcome the brittleness and fragility of existing porous composite materials. Furthermore, the research direction of this invention is to use this material to recycle carbon dioxide using microwave heating, and even to recycle carbon dioxide and organic matter such as biomass, plastics, and VOCs simultaneously.

[0015] Summary of the Invention

[0016] 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 problems of high brittleness and easy damage, since carbon fiber can both absorb and reflect microwaves, and weaving carbon fiber can 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 high temperatures exceeding 1000°C under microwave irradiation.

[0017] Based on the above findings, the purpose of the present invention is to provide a fiber assembly, a preparation method and application thereof, and a method for preparing synthesis gas using carbon dioxide.

[0018] To address the problems encountered in the prior art, the present invention provides a method for simultaneously recycling biomass and carbon dioxide using microwaves. This method utilizes a carbon fiber aggregate that can generate high temperatures and plasma in a microwave field containing carbon dioxide gas to efficiently crack biomass. By utilizing the properties of biomass producing coke and tar, and carbon dioxide converting to carbon monoxide under microwave plasma and high temperatures, the biomass and carbon dioxide are simultaneously and efficiently converted into synthesis gas with carbon monoxide as the main component.

[0019] The present invention also provides a method for simultaneously recycling polyolefins and carbon dioxide using microwaves. This method utilizes a carbon fiber aggregate that can generate high temperatures and plasma in a microwave field containing carbon dioxide gas to efficiently crack polyolefins. By utilizing the properties of polyolefins, which produce coke and tar, and carbon dioxide, which are converted into carbon monoxide under microwave plasma and high temperatures, the polyolefins and carbon dioxide are simultaneously and efficiently converted into synthesis gas with carbon monoxide as the main component.

[0020] The present invention also provides a method for the simultaneous recovery and utilization of VOCs and carbon dioxide using microwaves. This method utilizes a carbon fiber aggregate that can generate high temperatures and plasma in a microwave field containing carbon dioxide gas to efficiently crack VOCs into methane, ethylene, hydrogen, and amorphous carbon. The amorphous carbon and carbon dioxide can then be converted into carbon monoxide at high temperatures, thereby achieving the simultaneous and efficient recovery and utilization of VOCs and carbon dioxide.

[0021] A first aspect of the present invention is a carbon fiber aggregate comprising a plurality of randomly arranged carbon fiber basic units, wherein the carbon fiber basic units comprise a carbon fiber bundle formed by a plurality of carbon fibers and an optional single carbon fiber; the carbon fiber bundle is a fixed carbon fiber bundle; and the carbon fiber bundle is provided with at least one fixed node.

[0022] 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 More than one.

[0023] In a preferred embodiment of the present invention, the carbon fiber basic unit is a carbon fiber bundle formed by multiple carbon fibers and an optional single carbon fiber, that is, the carbon fiber basic unit is a carbon fiber bundle formed by multiple carbon fibers, or the carbon fiber basic unit is a carbon fiber bundle formed by multiple carbon fibers and a single carbon fiber.

[0024] In a preferred embodiment of the present invention, the carbon fiber aggregate presents a two-dimensional or three-dimensional spatial structure.

[0025] In a preferred embodiment of the present invention, at least part of two or more adjacent carbon fiber basic units are in contact with each other; preferably, the contact includes at least one of abutting, overlapping and interlacing with each other.

[0026] 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 , preferably 1×10 6 ~6×10 7More preferably, 1×10 6 ~2×10 7 indivual.

[0027] In a preferred embodiment of the present invention,

[0028] 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;

[0029] When the carbon fiber bundle is provided with two or more fixing nodes, 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 disconnected.

[0030] In a preferred embodiment of the present invention, the fixation includes bundling fixation and / or knotting fixation, and the fixation nodes include bundling nodes and / or knotting points. More preferably, the knotting fixation is that the carbon fiber bundles are fixed by knotting themselves; and / or, the bundles for bundling fixation are carbon fiber bundles.

[0031] The raw materials used for the carbon fiber aggregate described in the present invention can be commercially available. According to the present invention, the carbon fiber bundles can be various types of carbon fiber bundles available in the prior art. In a preferred embodiment of the present invention, the carbon fiber bundles, the bundling carbon fiber bundles, and the knotting carbon fiber bundles 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, they are selected from at least one of the following types of carbon fiber bundles: T300, T700, and T800; and more preferably, they are selected from at least one of the following types of carbon fiber bundles: T300 and T700.

[0032] According to the present invention, the number of carbon fibers contained in each bundle of carbon fiber filaments can be selected in a variety of ways. In a preferred embodiment of the present invention, 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, and most preferably 12K.

[0033] According to the present invention, the carbon fiber bundle is produced by processing (eg, fixing, partially breaking) carbon fiber tow filaments (eg, commercially available), and thus the carbon fiber tow filaments can be considered as a precursor of the carbon fiber bundle.

[0034] According to the present invention, the carbon fiber aggregate comprises a plurality of randomly arranged carbon fiber basic units, wherein the carbon fiber basic units are single carbon fibers and / or carbon fiber bundles formed from multiple carbon fibers. In a preferred embodiment of the present invention, the carbon fiber basic units are carbon fiber bundles formed from multiple carbon fibers, or the carbon fiber basic units comprise both single carbon fibers and carbon fiber bundles. In this preferred embodiment, the carbon fiber aggregate is more convenient to use and recycle.

[0035] 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 .

[0036] The second aspect of the present invention is to provide a method for preparing the carbon fiber aggregate according to the first aspect, comprising:

[0037] The carbon fiber bundle and optional single carbon fiber are assembled in a random arrangement to obtain the carbon fiber aggregate; wherein the preparation method of the carbon fiber bundle includes fixing the carbon fiber bundle filaments together and providing at least one fixed node on the carbon fiber bundle filaments, and when more than two fixed nodes are provided on the carbon fiber bundle filaments, the carbon fiber bundle filaments between adjacent fixed nodes are partially disconnected or completely disconnected.

[0038] The described collection refers to the aggregation of scattered carbon fiber basic units, 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 achieves contact between two or more adjacent carbon fiber basic units, and more preferably, at least partially achieves contact between two or more adjacent carbon fiber basic units in at least one manner including adjacency, overlap, and interlacing.

[0039] In a preferred embodiment of the present invention, the fixing includes bundling and / or knotting.

[0040] In a preferred embodiment of the present invention, the disconnection includes cutting and / or shearing.

[0041] 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.

[0042] In a more preferred embodiment of the present invention, when there are two or more fixed nodes on the carbon fiber bundle, the distance between adjacent fixed nodes is 1-50 mm, preferably 2-30 mm, and more preferably 5-20 mm.

[0043] The fixation includes bundling fixation and / or knotting fixation, and the fixation nodes include bundling nodes and / or knotting points. Preferably, the knotting fixation is performed by knotting the carbon fiber bundles themselves; and / or, the bundling fixation is performed by bundling the carbon fiber bundles; 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.

[0044] The equipment used in the preparation method of the present invention is all commonly used equipment.

[0045] The above-mentioned method for preparing carbon fiber aggregates directly uses high-strength carbon fibers as raw materials. Through simple processing, a flexible, high-temperature resistant material that can generate temperatures exceeding 1000°C in a microwave field can be prepared. The process flow is simple and easy, and large-scale preparation can be easily achieved.

[0046] 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,

[0047] Under microwave irradiation of 300W or more, the temperature of the material for microwave irradiation heating can reach above 1000°C.

[0048] 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 atmosphere. The reaction gas may be, for example, pure carbon dioxide or a mixture of carbon dioxide and water vapor.

[0049] 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,

[0050] 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.

[0051] 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 using carbon dioxide to prepare synthesis gas under a microwave field; preferably, the organic matter includes one or more of plastics, biomass, and organic volatiles.

[0052] A 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:

[0053] Reaction 1: contacting the carbon fiber aggregate, carbon dioxide and graphite to react and produce carbon monoxide; or

[0054] The second reaction is carried out by contacting the carbon fiber aggregate, carbon dioxide, water vapor and graphite to react and obtain carbon monoxide and hydrogen.

[0055] The present invention utilizes the thermal and catalytic effects of microwave irradiation of carbon fiber aggregates in a carbon dioxide atmosphere to generate plasma, which can react recycled carbon materials (such as graphite recovered from discarded lithium batteries) with carbon dioxide and water vapor to convert them into carbon monoxide and hydrogen to prepare synthesis gas, thereby converting and utilizing carbon dioxide while processing discarded carbon materials.

[0056] In a preferred embodiment of the present invention, in reaction 1:

[0057] The mass ratio of carbon fiber aggregate to graphite is (100:1) to (1:100), preferably (20:1) to (1:20), more preferably (10:1) to (1:10); and / or,

[0058] 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 0.1-200 min, preferably 0.5-150 min, most preferably 1-100 min.

[0059] In a preferred embodiment of the present invention, in reaction 2:

[0060] The mass ratio of the carbon fiber aggregate to the graphite is (100:1) to (1:100), preferably (1:1) to (1:20), more preferably (1:1) to (1:10); and / or,

[0061] 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,

[0062] 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 0.1-200 min, preferably 0.5-150 min, most preferably 1-100 min.

[0063] According to a preferred embodiment of the present invention, the method for preparing synthesis gas using carbon dioxide comprises the following steps:

[0064] a. placing the carbon fiber aggregate and graphite in a sealable reaction container made of microwave-transparent material;

[0065] b. introducing carbon dioxide into the reaction vessel, or introducing a mixture of carbon dioxide and water vapor into the reactor;

[0066] c. Start the microwave, place the reaction vessel under the microwave field to react, obtain gaseous products, and collect the gaseous products;

[0067] Preferably,

[0068] The graphite is derived from waste graphite, more preferably graphite recovered from discarded lithium batteries; and / or,

[0069] The microwave irradiation atmosphere optionally further contains nitrogen and / or an inert gas. Preferably, the inert gas is selected from argon.

[0070] According to the present invention, a microwave-transparent reaction vessel refers to a vessel through which microwaves can penetrate the walls and radiate to the sample. The reaction vessel can be made of any of the conventional microwave-transparent materials (e.g., quartz, alumina, boron nitride) that are resistant to high temperatures exceeding 1000°C.

[0071] 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 pyrolysis reactors), etc.

[0072] The aforementioned collection of gaseous products is a common method in the prior art, preferably carried out under an inert atmosphere. For example, if a microwave oven is used as the microwave field, the gas collection method is as follows: in a nitrogen-protected glove box, a quartz crucible containing waste plastics and porous composite materials is placed in a vacuum bag and sealed. After the microwave reaction, the crucible is unscrewed through the vacuum bag and a syringe is inserted into the vacuum bag to obtain a sample. Alternatively, an industrial-style microwave oven with an air inlet and outlet (such as a microwave pyrolysis reactor) is used for gas collection: nitrogen is purged during the reaction process and a gas collection bag is used to collect samples at the outlet.

[0073] Through the above technical solution, 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 over 1000°C under microwave irradiation. It overcomes the problem of high brittleness and easy damage of porous composite materials in the prior art. In addition, the carbon fiber aggregate of the present invention has simple raw materials, is easy to prepare, and has extremely high promotion and application value.

[0074] Carbon monoxide and hydrogen are important chemical raw materials. By adopting the synthesis gas preparation method of the present invention and using carbon fiber aggregates as carbon fiber microwave heating materials, carbon dioxide can be effectively converted into carbon monoxide, or carbon dioxide and water can be converted into carbon monoxide and hydrogen, thereby realizing the resource utilization of carbon dioxide and recycling graphite in discarded batteries, which has extremely high application value.

[0075] A seventh aspect of the present invention is to provide a method for simultaneously recovering biomass and carbon dioxide using microwaves, comprising:

[0076] The biomass is brought into contact with the carbon fiber aggregate, and microwaves are applied to the biomass and the carbon fiber aggregate in an atmosphere containing carbon dioxide gas, so that the biomass reacts with the carbon dioxide and is converted into a gas product with carbon monoxide as a main component;

[0077] The carbon fiber aggregate is the carbon fiber aggregate described in the first aspect or the carbon fiber aggregate prepared by the preparation method described in the second aspect.

[0078] Through the above technical solution, the present invention brings biomass into contact with a carbon fiber aggregate, applies microwaves to the biomass and the carbon fiber aggregate in an atmosphere containing carbon dioxide gas, and the carbon fiber aggregate generates high temperature and plasma in the microwave field under the carbon dioxide atmosphere. Under the combined action of high temperature and plasma, the biomass and carbon dioxide are converted into a gas product (i.e., synthesis gas) with carbon monoxide as the main component.

[0079] In the present invention, the gas product with carbon monoxide as the main component means that, based on volume content, the total volume of the gas product is 100%, the carbon monoxide content in the gas product is 20% or more, preferably 40% or more, more preferably 50% or more.

[0080] According to the present invention, the weight ratio of biomass to carbon fiber aggregate can be selected within a wide range. In a preferred embodiment of the present invention, the weight ratio of biomass to carbon fiber aggregate is (1:100) to (100:1), preferably (1:50) to (50:1), and more preferably (1:20) to (20:1).

[0081] In a preferred embodiment of the present invention, the gas containing carbon dioxide comprises pure carbon dioxide gas or a mixed gas containing carbon dioxide; preferably, the mixed gas containing carbon dioxide is a mixed gas of carbon dioxide and nitrogen and / or inert gas and / or water vapor; more preferably, the inert gas is at least one of argon and helium.

[0082] In a preferred embodiment of the present invention, the volume fraction of carbon dioxide in the carbon dioxide mixed gas is 5% to 99.9%, preferably 10% to 99.9%, and most preferably 20% to 99.9%.

[0083] According to the present invention, the power of the microwave can be selected within a wide range. In a preferred embodiment of the present invention, the power of the microwave is 1W to 100KW, preferably 200W to 50KW, and most preferably 500W to 20KW.

[0084] According to the present invention, the microwave time can be selected within a wide range. In a preferred embodiment of the present invention, the microwave time is 0.1 to 200 min, preferably 0.5 to 150 min, and most preferably 1 to 100 min.

[0085] In the present invention, the temperature of the carbon fiber aggregate exceeds 1000° C., so that the biomass is cracked.

[0086] The biomass and the carbon fiber aggregate can be brought into contact in various ways, as long as the biomass and the carbon fiber aggregate are in contact. In a preferred embodiment of the present invention, the biomass and the carbon fiber aggregate are brought into contact by one or more of the following methods: placing the biomass on the carbon fiber aggregate, placing it in a cavity formed by the carbon fiber aggregate, being covered by the carbon fiber aggregate, and being mixed with the carbon fiber aggregate.

[0087] According to the present invention, the biomass can be selected from a wide range. In a preferred embodiment of the present invention, the biomass is various plants and animals and / or algae produced by photosynthesis, each containing cellulose, hemicellulose and lignin; preferably,

[0088] The biomass is at least one of straw, bagasse, branches, leaves, wood chips, rice husks, straw, peanut shells, coconut shells, palm seed shells and corn cobs.

[0089] In a preferred embodiment of the present invention, the method comprises the following steps:

[0090] a. Dehydrating the biomass;

[0091] b. placing the dehydrated biomass and carbon fiber aggregate in a sealable reaction container made of microwave-transparent material;

[0092] c. introducing a gas containing carbon dioxide into the reaction vessel to replace the air;

[0093] d. Start the microwave, place the reaction container under the microwave field to react, and collect the gas products generated by the reaction.

[0094] The method for simultaneously recycling biomass and carbon dioxide using microwaves specifically comprises the following steps:

[0095] a. Dehydration of the biomass at 50°C-200°C for 1-240 minutes. The dehydration equipment may be commercially available drying equipment such as a blower dryer, microwave oven, or thermal radiation apparatus. Alternatively, the biomass may be dried in the sun or by air drying, so that the biomass does not suffer a thermal weight loss greater than 1% within 10 minutes at 200°C.

[0096] b. placing the biomass and the carbon fiber aggregate together in any manner so that the biomass can contact the carbon fiber aggregate;

[0097] c. introducing a gas containing carbon dioxide into the reaction system to replace the air;

[0098] d. Start the microwave and collect the gas products generated by the reaction.

[0099] 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 pyrolysis reactors), etc.

[0100] According to the present invention, the microwave transparent material means that microwaves can penetrate the wall of the reaction container made of the material and radiate to the sample.

[0101] The device for placing or carrying the biomass and carbon fiber aggregate in the method of the present invention can be selected from various containers or pipes in the prior art that can be penetrated by microwaves and can withstand high temperatures above 1200°C, such as quartz crucibles, quartz reactors, quartz tubes, alumina crucibles, alumina reactors, alumina tubes, etc.

[0102] In the method of the present invention, biomass is cracked and then gasified, and the gas obtained after cracking is collected for subsequent processing, such as gas separation and use as fuel or as chemical industry raw material for subsequent reaction and production.

[0103] The gas product collection method is conventional in the prior art and is preferably carried out under an inert atmosphere. For example, if a microwave oven is used as the microwave field, the gas collection method is as follows: in a nitrogen-protected glove box, a quartz crucible containing waste plastics and porous composite materials is placed in a vacuum bag and sealed. After the microwave reaction, the crucible is unscrewed through the vacuum bag and a syringe is inserted into the vacuum bag to obtain a sample. Alternatively, an industrial microwave oven with an air inlet and outlet (such as a microwave pyrolysis reactor) is used for gas collection: nitrogen is purged during the reaction and a gas collection bag is used to collect samples at the outlet.

[0104] The carbon fiber aggregate described in the method for simultaneously recovering biomass and carbon dioxide using microwaves is a material composed of a large number of carbon fiber ends aggregated in a disordered arrangement, wherein the carbon fiber ends can generate plasma under microwave irradiation. The present invention controls the number of carbon fiber ends contained in each gram of the carbon fiber aggregate to obtain a carbon fiber aggregate that, although pure carbon fiber, can generate plasma and temperatures exceeding 1000°C under microwave irradiation. This overcomes the brittleness and fragility of porous composite materials in the prior art. Furthermore, the carbon fiber aggregate of the present invention uses simple raw materials, is easy to prepare, and has extremely high application value.

[0105] The present invention adopts an indestructible carbon fiber aggregate, which can generate plasma in a microwave field containing a carbon dioxide atmosphere, that is, it reduces the coke and tar produced by biomass cracking, improves the utilization rate of biomass microwave cracking, and recycles carbon dioxide at the same time, achieving efficient recycling of carbon dioxide and biomass at the same time, and has a wide application market.

[0106] An eighth aspect of the present invention is to provide a method for simultaneously recovering polyolefin and carbon dioxide using microwaves, comprising:

[0107] The polyolefin is brought into contact with the carbon fiber aggregate, and microwaves are applied to the polyolefin and the carbon fiber aggregate in an atmosphere containing carbon dioxide gas, so that the polyolefin reacts with the carbon dioxide to convert it into a gas product with carbon monoxide as a main component;

[0108] The carbon fiber aggregate is the carbon fiber aggregate described in the first aspect or the carbon fiber aggregate prepared by the preparation method described in the second aspect.

[0109] Through the above technical scheme, the present invention brings polyolefin into contact with a carbon fiber aggregate, applies microwaves to the polyolefin and the carbon fiber aggregate in an atmosphere containing carbon dioxide gas, and the carbon fiber aggregate generates high temperature and plasma in the microwave field under the carbon dioxide atmosphere. Under the combined action of high temperature and plasma, the polyolefin and carbon dioxide are converted into a gas product (i.e., synthesis gas) with carbon monoxide as the main component.

[0110] In the present invention, the gas product with carbon monoxide as the main component means that, based on volume content, the total volume of the gas product is 100%, the carbon monoxide content in the gas product is 20% or more, preferably 40% or more, more preferably 50% or more.

[0111] In the present invention, the weight ratio of the polyolefin to the carbon fiber aggregate is preferably (1:100) to (100:1), preferably (1:50) to (50:1), and more preferably (1:30) to (30:1).

[0112] In the present invention, preferably, the gas containing carbon dioxide comprises pure carbon dioxide gas or a mixed gas containing carbon dioxide; more preferably,

[0113] The carbon dioxide-containing mixed gas is a mixed gas of carbon dioxide, nitrogen and / or an inert gas and / or water vapor; more preferably, the inert gas is at least one of argon and helium.

[0114] More preferably, the volume fraction of carbon dioxide in the carbon dioxide mixed gas is 5% to 99.9%, preferably 10% to 99.9%, and most preferably 20% to 99.9%.

[0115] According to the present invention, the power of the microwave can be selected within a wide range. In a preferred embodiment of the present invention, the power of the microwave is 1W to 100KW, preferably 200W to 50KW, and most preferably 500W to 20KW.

[0116] According to the present invention, the microwave time can be selected within a wide range. In a preferred embodiment of the present invention, the microwave time is 0.1 to 200 min, preferably 0.5 to 150 min, and most preferably 1 to 100 min.

[0117] In the present invention, the temperature of the carbon fiber aggregate exceeds 1000° C., so that the polyolefin is cracked.

[0118] The polyolefin and the carbon fiber aggregate can be brought into contact in various ways, as long as the polyolefin and the carbon fiber aggregate are in contact. Preferably, the polyolefin and the carbon fiber aggregate are brought into contact by one or more of the following methods: the polyolefin is placed on the carbon fiber aggregate, placed in a cavity formed by the carbon fiber aggregate, covered by the carbon fiber aggregate, or blended with the carbon fiber aggregate.

[0119] According to the present invention, the polyolefin can be selected from a wide range. In a preferred embodiment of the present invention, the polyolefin is a polyolefin prepared by homopolymerization or copolymerization of at least one of ethylene, propylene, butene, α-olefin, cycloolefin, 4-methyl-1-pentene, and acrylic acid monomers, as well as a mixture of the polyolefins.

[0120] The polyolefin described in the present invention can be various types of polyethylene (PE), polypropylene (PP), poly-1-butene (PB-1), ethylene-vinyl acetate copolymer (EVA), polyolefin elastomer (POE), cycloolefin homopolymer / copolymer (COP / COC), poly-4-methyl-1-pentene (PMP), ethylene-vinyl alcohol copolymer (EVOH), ethylene-acrylic acid copolymer (EAA), etc., which are prepared by homopolymerization or copolymerization of ethylene, propylene, butene, α-olefin, cycloolefin, 4-methyl-1-pentene, acrylic acid monomers, etc., as well as mixtures of the above polyolefins.

[0121] Preferably, the polyolefin is at least one of polyethylene, polypropylene, poly-1-butene, ethylene-vinyl acetate copolymer, polyolefin elastomer, cycloolefin homopolymer / copolymer, poly-4-methyl-1-pentene, ethylene-vinyl alcohol copolymer, and ethylene-acrylic acid copolymer.

[0122] In a preferred embodiment of the present invention, the method comprises the following steps:

[0123] a. Removing small molecules from polyolefins;

[0124] b. placing the treated polyolefin and carbon fiber aggregate in a sealable reaction container made of microwave-transparent material;

[0125] c. introducing a gas containing carbon dioxide into the reaction vessel to replace the air;

[0126] d. Start the microwave, place the reaction container under the microwave field to react, and collect the gas products generated by the reaction.

[0127] The method for simultaneously recycling polyolefin and carbon dioxide using microwaves comprises the following steps:

[0128] a. The polyolefin is subjected to a small molecule removal treatment at 50°C-200°C for 1 minute-240 minutes. The small molecule removal equipment can be a commercially available drying equipment, such as a blast dryer, a microwave oven, a thermal radiation instrument, etc., or the small molecule removal treatment can be carried out by sun drying, air drying, etc., so that the polyolefin does not produce a thermal weight loss of more than 1% within 10 minutes at 200°C;

[0129] b. placing the polyolefin and the carbon fiber aggregate together in any manner such that the polyolefin contacts the carbon fiber aggregate;

[0130] c. introducing pure carbon dioxide or a mixture of carbon dioxide and one or more of the following: nitrogen, argon, helium, or water vapor into the reaction system to replace the air;

[0131] d. Start the microwave and collect the gas products generated by the reaction.

[0132] 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 pyrolysis reactors), etc.

[0133] According to the present invention, the microwave transparent material means that microwaves can penetrate the wall of the reaction container made of the material and radiate to the sample.

[0134] The device for placing or carrying the polyolefin and carbon fiber aggregate in the method of the present invention can be selected from various containers or pipes in the prior art that can be penetrated by microwaves and can withstand high temperatures above 1200°C, such as quartz crucibles, quartz reactors, quartz tubes, alumina crucibles, alumina reactors, alumina tubes, etc.

[0135] In the method of the present invention, polyolefin is cracked and then gasified, and the gas obtained after cracking is collected for subsequent treatment, such as gas separation and use as fuel or as chemical industry raw material for subsequent reaction and production.

[0136] The gas product collection method is conventional in the prior art and is preferably carried out under an inert atmosphere. For example, if a microwave oven is used as the microwave field, the gas collection method is as follows: in a nitrogen-protected glove box, a quartz crucible containing waste plastics and porous composite materials is placed in a vacuum bag and sealed. After the microwave reaction, the crucible is unscrewed through the vacuum bag and a syringe is inserted into the vacuum bag to obtain a sample. Alternatively, an industrial microwave oven with an air inlet and outlet (such as a microwave pyrolysis reactor) is used for gas collection: nitrogen is purged during the reaction and a gas collection bag is used to collect samples at the outlet.

[0137] The carbon fiber aggregate described in the method for simultaneously recovering polyolefins and carbon dioxide using microwaves is a material composed of a large number of randomly arranged carbon fiber ends, wherein the carbon fiber ends can generate plasma under microwave irradiation. By controlling the number of carbon fiber ends contained in each gram of the carbon fiber aggregate, the present invention obtains a carbon fiber aggregate that, although pure carbon fiber, can generate plasma and temperatures exceeding 1000°C under microwave irradiation. This overcomes the brittleness and fragility of porous composite materials in the prior art. Furthermore, the carbon fiber aggregate of the present invention uses simple raw materials, is easy to prepare, and has extremely high application value.

[0138] The present invention adopts an indestructible carbon fiber aggregate, which can generate plasma in a microwave field containing a carbon dioxide atmosphere, that is, it can reduce the coke and tar produced by polyolefin cracking, improve the utilization rate of polyolefin microwave cracking, and recycle carbon dioxide at the same time, thereby achieving efficient recycling of carbon dioxide and polyolefin at the same time, and has a wide application market.

[0139] A ninth aspect of the present invention is to provide a method for simultaneously recovering VOCs and carbon dioxide using microwaves, comprising:

[0140] A mixed gas containing carbon dioxide and VOCs is brought into contact with a carbon fiber aggregate, and under the condition of applying microwaves to the carbon fiber aggregate, the VOCs react with the carbon dioxide to convert into cracked gas;

[0141] The carbon fiber aggregate is the carbon fiber aggregate described in the first aspect or the carbon fiber aggregate prepared by the preparation method described in the second aspect.

[0142] Research has found that VOCs can be cracked into methane, ethylene, hydrogen, and amorphous carbon under microwave plasma at temperatures exceeding 1000°C. Amorphous carbon, at 1000°C, reacts with carbon dioxide to produce carbon monoxide. Methane, carbon monoxide, and hydrogen are important energy fuels. Ethylene can be used to produce polyethylene, and hydrogen and carbon monoxide can be used to produce alkanes through Fischer-Tropsch synthesis. Therefore, the technology of simultaneously converting VOCs and carbon dioxide into methane, ethylene, carbon monoxide, and hydrogen has extremely high economic value and market applications.

[0143] Through the above-mentioned technical solution of the present invention, the carbon fiber aggregate is a material composed of a large number of carbon fiber ends aggregated in a disordered arrangement, wherein plasma can be generated between the carbon fiber ends under microwave irradiation. When a mixture of VOCs and carbon dioxide flows through a wave-transmitting container containing the carbon fiber aggregate, the carbon fiber aggregate is subjected to microwave irradiation. The carbon fiber aggregate generates high temperatures and plasma in the microwave field containing an atmosphere of carbon dioxide. Under the combined action of the high temperature and plasma, the VOCs and carbon dioxide are converted into a gas composed primarily of carbon monoxide, methane, ethylene, and hydrogen.

[0144] According to the present invention, preferably, in the mixed gas containing carbon dioxide and VOCs, based on the total volume of VOCs and carbon dioxide as 100%, the content of VOCs is 10% to 90%, preferably 20% to 80%, and more preferably 30% to 70%.

[0145] The amount of the carbon fiber aggregate is greater than or equal to 1% of the total mass of the mixed gas of carbon dioxide and VOCs to be treated, preferably greater than or equal to 3%, more preferably greater than or equal to 5%.

[0146] The pyrolysis gas contains methane, ethylene, hydrogen and carbon monoxide. Preferably, the total content of methane, ethylene, hydrogen and carbon monoxide in the pyrolysis gas is greater than 50%, preferably greater than 80%, and more preferably greater than 90%, calculated by volume, with the total volume of the pyrolysis gas being 100%.

[0147] According to the present invention, preferably, the power of the microwave is 1W to 100KW, preferably 200W to 50KW, most preferably 500W to 20KW; and / or,

[0148] The microwave time is 0.1 to 200 min, preferably 0.5 to 150 min, most preferably 1 to 100 min; and / or,

[0149] The temperature of the carbon fiber aggregate exceeds 1000°C, causing VOCs to decompose.

[0150] According to the present invention, VOCs are preferably able to fully contact the carbon fiber aggregate. Specifically, preferably, the carbon fiber aggregate is contacted by introducing the carbon fiber aggregate into a reactor through the pores of the carbon fiber aggregate, either separately or simultaneously. More preferably, the carbon fiber aggregate is introduced separately or simultaneously from the bottom of the carbon fiber aggregate, or the carbon fiber aggregate is placed in a U-shaped container, and the carbon fiber aggregate and VOCs are introduced separately or simultaneously from one end of the U-shaped container.

[0151] According to the present invention, the VOCs, i.e., volatile organic compounds, are organic compounds with a boiling point of less than 260°C under standard atmospheric pressure; preferably, the VOCs include 2-methylpentane, hydrogen, n-hexane, 2,2,4-trimethylpentane, n-heptane, 2,3,4-trimethylpentane, methylcyclohexane, n-octane, n-nonane, n-decane, propane, isobutane, isobutene, n-butane, cyclopentane, isopentane, n-pentane, ethane, n-undecane, n-dodecane, methylcyclopentane, 3-methylpentane, 3-methylhexane, 2-methylhexane, 2,4-dimethylpentane, 2,2- One or more of dimethylbutane, 2,3-dimethylbutane, cyclohexane, 2-methylheptane, 3-methylheptane, 2,3-dimethylpentane, propylene, trans-2-butene, 1-butene, cis-2-butene, 1-pentene, cis-2-pentene, ethylene, acetylene, benzene, ethylbenzene, o-xylene, m-xylene, p-xylene, methane, toluene, m-ethyltoluene, p-ethyltoluene, o-ethyltoluene, styrene, isopropylbenzene, n-propylbenzene, 1,3,5-trimethylbenzene, 1,2,4-trimethylbenzene, 1,2,3-trimethylbenzene, m-diethylbenzene, p-diethylbenzene, acetone, 1,3-butadiene, and carbon monoxide.

[0152] According to the present invention, preferably, the method for simultaneously recovering and utilizing VOCs and carbon dioxide using microwaves comprises the following steps:

[0153] a. placing the carbon fiber aggregate in a sealable reaction container made of microwave-transparent material;

[0154] b. introducing carbon dioxide into the reaction vessel to replace the air, and then introducing carbon dioxide and VOCs;

[0155] c. Start the microwave, place the reaction vessel under the microwave field to react, and collect the gaseous products generated by the reaction. Preferably, VOCs are introduced from the bottom of the carbon fiber aggregate, or the carbon fiber heating material is placed in a U-shaped wave-transmitting container, and VOCs are introduced from one end of the U-shaped wave-transmitting container.

[0156] 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 pyrolysis reactors), etc.

[0157] 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 pyrolysis reactors), etc.

[0158] According to the present invention, the microwave transparent material means that microwaves can penetrate the wall of the reaction container made of the material and radiate to the sample.

[0159] The device for placing or carrying the carbon fiber aggregate in the method of the present invention can be selected from various containers or pipes in the prior art that can be penetrated by microwaves and can withstand high temperatures above 1200°C, such as quartz crucibles, quartz reactors, quartz tubes, alumina crucibles, alumina reactors, alumina tubes, etc.

[0160] In the method of the present invention, VOCs are cracked and then gasified, and the gas obtained after cracking is collected for subsequent treatment, such as gas separation and use as fuel or as chemical industry raw material for subsequent reaction and production.

[0161] The gas product collection method is conventional in the prior art and is preferably carried out under an inert atmosphere. For example, if a microwave oven is used as the microwave field, the gas collection method is as follows: in a nitrogen-protected glove box, a quartz crucible containing waste plastics and porous composite materials is placed in a vacuum bag and sealed. After the microwave reaction, the crucible is unscrewed through the vacuum bag and a syringe is inserted into the vacuum bag to obtain a sample. Alternatively, an industrial microwave oven with an air inlet and outlet (such as a microwave pyrolysis reactor) is used for gas collection: nitrogen is purged during the reaction and a gas collection bag is used to collect samples at the outlet.

[0162] The carbon fiber aggregate described in the method for simultaneously recovering VOCs and carbon dioxide using microwaves is a material composed of a large number of carbon fiber ends aggregated in a disordered manner, wherein plasma can be generated between the carbon fiber ends under microwave irradiation. The present invention controls the number of carbon fiber ends contained in each gram of the carbon fiber aggregate to obtain a carbon fiber aggregate. Although the carbon fiber aggregate is pure carbon fiber, it can generate plasma and temperatures exceeding 1000°C under microwave irradiation. This overcomes the problem of high brittleness and easy damage of porous composite materials in the prior art. Moreover, the carbon fiber aggregate of the present invention uses simple raw materials, is easy to prepare, and has extremely high value for promotion and application.

[0163] The present invention uses an indestructible carbon fiber aggregate, which can generate plasma in a microwave field containing a carbon dioxide atmosphere, and efficiently crack VOCs into methane, ethylene, hydrogen and amorphous carbon. The amorphous carbon and carbon dioxide can be converted into carbon monoxide at high temperature, thereby realizing the simultaneous and efficient recycling of VOCs and carbon dioxide. BRIEF DESCRIPTION OF THE DRAWINGS

[0164] FIG1 is a morphological photograph of a 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;

[0165] FIG2 is a morphological photograph of a carbon fiber aggregate in Example 2 of the present invention; wherein the carbon fiber basic unit is a single carbon fiber;

[0166] FIG3 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

[0167] The present invention will be described in detail below with reference to specific embodiments. It is necessary to point out that the following embodiments are only used to further illustrate the present invention and are not to be construed as limiting the scope of protection of the present invention. Non-essential improvements and adjustments made by those skilled in the art to the present invention based on the contents of the present invention still fall within the scope of protection of the present invention.

[0168] The experimental data in the examples were measured using the following instruments and measurement methods:

[0169] In the embodiment, the collected synthesis gas components are subjected to chromatographic analysis in the following manner:

[0170] 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 a nitrogen 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 a carrier gas was used to detect CO, CO2, N2, and O2. In order to perform quantitative analysis, the response factor was determined by using an RGA (refinery gas analysis) calibration gas standard.

[0171] The number of carbon fiber ends contained in each gram of the carbon fiber aggregate is obtained by theoretical calculation. The specific calculation method is:

[0172] (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:

[0173] N is the number of carbon fiber ends per gram of the carbon fiber aggregate (unit: pieces), ρ is the carbon fiber density (unit: g / m 3 ), d is the carbon fiber diameter (unit: m), and L is the carbon fiber filament length (unit: m).

[0174] (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:

[0175] N=[(n-1)×2×t+2]×k / m

[0176] N is the number of carbon fiber ends contained in each gram of the carbon fiber aggregate (unit: pieces), n is the number of knotting points on the carbon fiber bundle; t is the ratio of the long carbon fiber bundle 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).

[0177] Take the calculation method described in Example 1 as an example. A 5000mm long T300 carbon fiber 12K bundle is knotted by itself with a knotting spacing 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 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 indivual.

[0178] (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:

[0179] N=[(n-1)×2×t×k+2k+c1×n1×k1)] / m

[0180] N is the number of carbon fiber ends contained in each gram of the carbon fiber aggregate (unit: pieces), n is the total number of fixed nodes formed by knotting and bundling on the carbon fiber bundle; t is the ratio of the long carbon fiber bundles cut at the fixed nodes, and k is the number of carbon fibers in the long carbon fiber bundles;

[0181] c1 is the number of ends of each bundle at each fixed node when the fixed node is a bundling node; n1 is the number of bundling nodes; k1 is the number of carbon fibers contained in the bundle of the bundling node.

[0182] m is the total mass of the carbon fiber bundle (unit: g).

[0183] (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:

[0184] N is the number of carbon fiber ends contained in each gram of the carbon fiber aggregate (unit: pieces), n is the total number of fixed nodes formed by knotting and bundling on the carbon fiber bundles in the part constructed with carbon fiber bundles as the basic unit in the carbon fiber aggregate; t is the ratio of the long carbon fiber bundles at the fixed node in the part constructed with 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 carbon fiber bundles as the basic unit in the carbon fiber aggregate; c1 is the number of ends of each bundle of each fixed node in the part constructed with carbon fiber bundles as the basic unit in the carbon fiber aggregate when the fixed node is a bundling node; n1 is the number of bundling nodes in the part constructed with carbon fiber bundles as the basic unit in the carbon fiber aggregate; k1 is the number of carbon fibers containing carbon fiber bundles in the bundle of the bundling node 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 / m 3 ), d is the carbon fiber diameter in the part constructed with a single carbon fiber as the basic unit in the carbon fiber aggregate (unit: m), L is the carbon fiber filament length in the part constructed with a single carbon fiber as the basic unit in the carbon fiber aggregate (unit: m); m1 is the total mass of the part constructed with carbon fiber bundles as the basic unit in the carbon fiber aggregate (unit: g), and m2 is the total mass of the part constructed with a single carbon fiber as the basic unit in the carbon fiber aggregate (unit: g).

[0185] 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.

[0186] 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.

[0187] Preparation of carbon fiber aggregates:

[0188] Example 1

[0189] A 5000 mm long T300 carbon fiber 12K bundle (3.96 g, Weihai Guangwei Composite Materials Group Co., Ltd.) was taken and tied with a single knot at a 10 mm knotting interval, resulting in 499 knots. Two-thirds of the carbon fiber bundle at a distance of 5 mm from the knotting point was cut to form a carbon fiber aggregate. The material was rolled up and placed in a quartz jar. The number of carbon fiber ends per gram of the carbon fiber aggregate was approximately 2×10 6 At this point, the material can generate plasma and an equilibrium temperature of 1200°C under pure carbon dioxide atmosphere through 900W microwave irradiation.

[0190] Comparative Example 1

[0191] A 5000mm long T300 carbon fiber 12K bundle (3.96g, Weihai Guangwei Composite Materials Group Co., Ltd.) was taken and tied with a single knot at a knotting distance of 250mm, resulting in 19 knots. Two-thirds of the carbon fiber bundle at a distance of 125mm between the knotting points was cut to make a carbon fiber aggregate, which was then rolled up and placed in a quartz jar. The number of carbon fiber ends per gram of the carbon fiber aggregate was approximately 7.9×10 4 At this time, when the material is irradiated with 900W microwaves in a pure carbon dioxide atmosphere, the equilibrium temperature of the material can only reach 300°C.

[0192] Example 2

[0193] Take 4g of T300 single 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 per gram of carbon fiber aggregate is about 9.8×10 6 At this time, the material can generate plasma and reach an equilibrium temperature of 1400°C under pure carbon dioxide atmosphere through 1200W microwave irradiation.

[0194] Comparative Example 2

[0195] Take 4g of T300 single 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, when the material is irradiated with 1200W microwaves in a pure carbon dioxide atmosphere, the material temperature can only reach an equilibrium temperature of 600°C.

[0196] Example 3

[0197] A 5600 mm long T700 carbon fiber 12K bundle (4.48 g, 7 μm diameter, Weihai Guangwei Composite Materials Group Co., Ltd.) was taken and tied with a single knot at a knotting distance of 14 mm, resulting in 399 knots. The carbon fiber bundle was cut into two-thirds of the knotting point at a distance of 7 mm from the knotting point to form a carbon fiber aggregate. The material was rolled up and placed in a quartz jar. The number of carbon fiber ends per gram of the carbon fiber aggregate was about 1.4 × 10 6 At this time, the material can generate plasma and reach an equilibrium temperature of 1100°C under a mixed gas atmosphere of carbon dioxide and water vapor with a volume ratio of 90:10 through 700W microwave irradiation.

[0198] Comparative Example 3

[0199] A 5000mm long T700 carbon fiber 12K bundle (4.0g, Weihai Guangwei Composite Materials Group Co., Ltd.) was taken and tied with a single knot at a knotting distance of 250mm, resulting in 19 knots. Two-thirds of the carbon fiber bundle at a distance of 125mm between the knotting points was cut to make a carbon fiber aggregate, which was then rolled up and placed in a quartz jar. The number of carbon fiber ends per gram of the carbon fiber aggregate was approximately 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 equilibrium temperature of the material could only reach 100°C.

[0200] Example 4

[0201] Take 6g of T700 single carbon fiber (short carbon fiber, density 1.8g / cm 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 reach an equilibrium temperature of 1050°C under a mixed gas atmosphere of carbon dioxide and water vapor with a volume ratio of 30:70 through 1200W microwave irradiation.

[0202] Comparative Example 4

[0203] Take 6g of T700 single carbon fiber (short carbon fiber, density 1.8g / cm 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 microwaves in a mixed gas atmosphere of carbon dioxide and water vapor with a volume ratio of 30:70, and the equilibrium temperature of the material could only reach 900°C.

[0204] Example 5

[0205] Take a 2500mm long T300 carbon fiber 12K bundle (1.98g, Weihai Guangwei Composite Materials Group Co., Ltd.), use a single knot knotting method, according to the knotting spacing of 10mm, to tie 249 knots. Cut the carbon fiber bundle 5mm away from the knotting point by two-thirds; take 3g of a T700 single 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 jar. The number of carbon fiber ends per gram of carbon fiber aggregate per unit mass was about 4.3×10 6 At this point, the material can generate plasma and an equilibrium temperature of 1280°C under pure carbon dioxide atmosphere through 900W microwave irradiation.

[0206] The carbon fiber aggregates prepared in Examples 1-5 each contain more than 1×10 6 Under the microwave irradiation in the atmosphere of pure carbon dioxide and mixed gas (carbon dioxide and water vapor), sufficient plasma can be generated to make the material equilibrium temperature greater than 1000°C. The carbon fiber aggregates prepared in Comparative Examples 1-4 have a number of carbon fiber ends per gram of carbon fiber aggregate less than 1×10 6 In the atmosphere of pure carbon dioxide and mixed gas (carbon dioxide and water vapor), microwave irradiation cannot generate sufficient plasma to make the material equilibrium temperature less than 900℃.

[0207] Example of carbon fiber aggregates used in preparing synthesis gas from carbon dioxide:

[0208] Example 6A

[0209] 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 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 1A.

[0210] Example 7A

[0211] 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 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 1A.

[0212] Example 8A

[0213] 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 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 1A.

[0214] Example 9A

[0215] The carbon fiber aggregate (8 g) prepared in Example 3 and graphite (2 g) from discarded batteries 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 1A.

[0216] Example 10A

[0217] 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 with a volume ratio of 30:70. The graphite was completely consumed, and the collected gas products are shown in Table 1A.

[0218] Example 11A

[0219] 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 with a volume ratio of 90:10. The graphite was completely consumed, and the collected gas products are shown in Table 1A.

[0220] Comparative Example 5A

[0221] Graphite (2 g) from discarded batteries was placed in a quartz jar and irradiated with microwaves at 900 W for 20 minutes under a pure carbon dioxide atmosphere. The mass of the graphite did not change, and the collected gas products are shown in Table 1A.

[0222] Comparative Example 6A

[0223] 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 min in a mixed gas atmosphere of carbon dioxide and water vapor with a volume ratio of 30:70. The mass of the graphite did not change, and the collected gas products are shown in Table 1A.

[0224] Table 1A

[0225] Examples 6A-8A demonstrate that microwave irradiation of graphite and carbon fiber aggregates from discarded batteries in a pure carbon dioxide atmosphere can efficiently convert the graphite and carbon dioxide into carbon monoxide. Examples 9A-11A demonstrate that microwave irradiation of graphite and carbon fiber aggregates from discarded batteries in a mixed gas atmosphere of carbon dioxide and water vapor can efficiently convert the graphite, carbon dioxide, and water vapor into carbon monoxide and hydrogen.

[0226] Compared with Example 6A, in Comparative Example 5A, when the carbon fiber aggregate is removed, the gaseous 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.

[0227] Comparing Comparative Example 6A with Example 10A, the gaseous product collected after microwave treatment after the carbon fiber aggregate was removed contained no carbon monoxide or hydrogen. This demonstrates that the use of the carbon fiber aggregate is key to the reaction of the carbon dioxide and water vapor mixture with graphite to produce carbon monoxide. Carbon monoxide and hydrogen form synthesis gas, an important chemical raw material. This demonstrates that the carbon fiber aggregate can effectively convert carbon dioxide into synthesis gas, achieving carbon dioxide resource utilization.

[0228] Example of simultaneous recycling of biomass and carbon dioxide using microwaves:

[0229] The experimental data in the examples were measured using the following instruments and measurement methods:

[0230] In the embodiment, the collected synthesis gas components are subjected to chromatographic analysis in the following manner:

[0231] 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 a nitrogen 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 a carrier gas was used to detect CO, CO2, N2, and O2. In order to perform quantitative analysis, the response factor was determined by using an RGA (refinery gas analysis) calibration gas standard.

[0232] In the embodiment, the residual rate of carbon-based solid matter after biomass pyrolysis is X c The content is analyzed by weighing method:

[0233] The mass of the biomass after drying is weighed as M1, and the mass of the solid matter remaining after biomass cracking is weighed as M2. Since biomass contains inorganic components such as silicate, the solid remaining after biomass cracking is burned in air at 800℃, and the mass of the solid matter after combustion is weighed as M3.

[0234] Residual rate of carbon-based solid matter after biomass pyrolysis X c =(M2-M3) / M1×100%

[0235] The raw materials of the embodiments of the invention are all commercially available.

[0236] Example 6B

[0237] Take straw, bagasse, branches, leaves, sawdust, rice husk, straw, peanut shell, coconut shell, palm seed shell and corn cob, and use a blast dryer to dehydrate at 200 ° C for 5 hours. Take 2g of dehydrated straw, bagasse, branches, leaves, sawdust, rice husk, straw, peanut shell, coconut shell, palm seed shell and corn cob respectively, and place them on the surface of 4g of carbon fiber aggregate obtained in Example 1, and then put the biomass and carbon fiber aggregate into a quartz jar. In a pure carbon dioxide atmosphere, use an industrial microwave oven to microwave irradiate for 10 minutes at a microwave power of 700W. All materials are gasified and cracked after microwave irradiation, leaving only a small amount of black residue. The residual rate of carbon-based solid matter X is measured by weighing. c , as shown in Table 1B, and the composition of the obtained gas phase product is shown in Table 2B.

[0238] Example 7B

[0239] Take straw, bagasse, branches, leaves, sawdust, rice husk, straw, peanut shells, coconut shells, palm seed shells and corn cobs, and use an industrial microwave oven to dehydrate them for 30 minutes at 350W power under air purge. Take 64g of dehydrated straw, bagasse, branches, leaves, sawdust, rice husk, straw, peanut shells, coconut shells, palm seed shells and corn cobs respectively, and mix them with 32g of the carbon fiber aggregate obtained in Example 1, and then put the biomass and carbon fiber aggregate into a quartz jar. In an atmosphere of a mixed gas with a volume ratio of carbon dioxide to nitrogen of 70:30, use an industrial microwave oven and microwave irradiate for 10 minutes at a microwave power of 2000W. All materials are gasified and cracked after microwave irradiation, leaving only a small amount of black residue. The residual rate of carbon-based solid matter X is measured by weighing. c , as shown in Table 1B, and the composition of the obtained gas phase product is shown in Table 2B.

[0240] Comparative Example 5B

[0241] The 4 g of carbon fiber aggregate obtained in Example 1 used in Example 6B was replaced with 4 g of silicon carbide powder. Other conditions were the same as in Example 6B. The microwave irradiation cracking product contained a large amount of black residue. The residual carbon-based solid matter rate X was measured by weighing. c , as shown in Table 1B.

[0242] Comparative Example 6B

[0243] The microwave irradiation gas environment used in Example 6B was replaced by pure nitrogen instead of pure carbon dioxide. Other conditions were the same as those in Example 6B. The microwave irradiation cracking product contained a large amount of black residue. The residual carbon-based solid matter rate X was measured by weighing. c , as shown in Table 1B.

[0244] Comparative Example 7B

[0245] 4 g of the carbon fiber aggregate obtained in Example 1 used in Example 6B was replaced with 4 g of the carbon fiber aggregate in Comparative Example 1. Other conditions were the same as in Example 6B. The microwave irradiation cracking product contained a large amount of black residue, and the carbon-based solid matter residual rate Xc was measured by weighing, as shown in Table 1B.

[0246] Table 1B

[0247] Table 2B. Gas phase composition of cracking products excluding nitrogen

[0248] As shown in Table 1B, the final carbon-based solid matter residual rate (X) of biomass cracked by microwave using carbon fiber aggregates in an atmosphere containing carbon dioxide gas is c ) are less than 5% (Example 6B and Example 7B), while the X of microwave pyrolysis of biomass using traditional microwave heating materials is c are greater than 20% (Comparative Example 5B), and if only carbon fiber aggregates are used and microwave pyrolysis of biomass is not performed in an atmosphere containing carbon dioxide, the final X c The results are both greater than 15% (Comparative Example 6B). It can be seen that the use of carbon fiber aggregates to perform microwave cracking of biomass in an atmosphere containing carbon dioxide gas can achieve more complete biomass cracking than other biomass cracking methods. In addition, since the temperature of the carbon fiber aggregate obtained in Comparative Example 1 can only reach 300°C under carbon dioxide microwave irradiation, only a small amount of biomass is decomposed at this temperature. Therefore, the number of carbon fiber ends contained in each gram of carbon fiber aggregate must reach 1×10 6 More than one can achieve the effect of cracking biomass.

[0249] As shown in Table 2B, the gases produced by biomass pyrolysis in Examples 6B and 7B, in addition to nitrogen, are mainly composed of carbon monoxide and hydrogen, of which the volume fraction of carbon monoxide is greater than 60% and the volume fraction of hydrogen is greater than 25%, and can be used as chemical raw materials or fuels.

[0250] The carbon fiber aggregates obtained in Example 2-5 were subjected to the same experiment as above, and similar experimental phenomena and results as those in Example 6B were obtained.

[0251] Example of simultaneous recycling of polyolefin and carbon dioxide using microwaves:

[0252] The experimental data in the examples were measured using the following instruments and measurement methods:

[0253] In the embodiment, the collected synthesis gas components are subjected to chromatographic analysis in the following manner:

[0254] 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 ASTM D1945-14. Hydrocarbons were analyzed on the FID channel. A TCD using a nitrogen 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 a carrier gas was used to detect CO, CO2, N2, and O2. For quantitative analysis, response factors were determined using RGA (refinery gas analysis) calibration gas standards.

[0255] In the embodiment, the residual rate of carbon-based solid matter after polyolefin cracking is X c The content is analyzed by weighing method:

[0256] The mass of the polyolefin after drying is weighed as M1, and the mass of the solid matter remaining after the polyolefin is cracked is weighed as M2.

[0257] Residual rate of carbon-based solid matter after polyolefin cracking X c =M2 / M1×100%

[0258] The raw materials of the embodiments of the invention are all commercially available.

[0259] Example 6C

[0260] Take polyethylene pellets, polypropylene flakes removed from discarded lunch boxes, poly-1 butene pellets, and ethylene-vinyl acetate copolymer removed from discarded shoe soles, and use a blast dryer to remove small molecules at 200°C for 5 hours. Take 2g of polyethylene pellets after small molecules are removed, polypropylene flakes removed from discarded lunch boxes, poly-1 butene pellets, and ethylene-vinyl acetate copolymer removed from discarded shoe soles, and place them on the surface of 4g of the carbon fiber aggregate obtained in Example 1. Then put the polyolefin and carbon fiber aggregate into a quartz jar. In a pure carbon dioxide atmosphere, use an industrial microwave oven to irradiate with a microwave power of 700W for 10 minutes. All materials are gasified and cracked after microwave irradiation, leaving only a small amount of black residue. The carbon-based solid matter residual rate X is measured by weighing. c , as shown in Table 1C, and the composition of the obtained gas phase product is shown in Table 2C.

[0261] Example 7C

[0262] Take polyethylene pellets, polypropylene flakes removed from discarded lunch boxes, poly-1 butene pellets, and ethylene-vinyl acetate copolymer removed from discarded shoe soles, and use an industrial microwave oven at 350W power for 30 minutes under air purge to remove small molecules. Take 64g of polyethylene pellets after small molecules are removed, polypropylene flakes removed from discarded lunch boxes, poly-1 butene pellets, and ethylene-vinyl acetate copolymer removed from discarded shoe soles, respectively, and mix them with 32g of carbon fiber aggregates obtained in Example 1, and then put the polyolefin and carbon fiber aggregates into a quartz jar. In an atmosphere of a mixed gas with a volume ratio of carbon dioxide to water vapor of 80:20, use an industrial microwave oven and microwave irradiate for 10 minutes at a microwave power of 2000W. All materials are gasified and cracked after microwave irradiation, leaving only a small amount of black residue. The residual rate of carbon-based solid matter X is measured by weighing. c , as shown in Table 1C, and the composition of the obtained gas phase product is shown in Table 2C.

[0263] Comparative Example 5C

[0264] The 4 g of carbon fiber aggregate obtained in Example 1 used in Example 6C was replaced with 4 g of silicon carbide powder. Other conditions were the same as those in Example 6C. The microwave irradiation cracking product contained a large amount of black residue. The residual carbon-based solid matter rate X was measured by weighing. c , as shown in Table 1C.

[0265] Comparative Example 6C

[0266] The microwave irradiation gas environment used in Example 6C was replaced by pure nitrogen instead of pure carbon dioxide. Other conditions were the same as those in Example 6C. The microwave irradiation cracking product contained a large amount of black residue. The residual carbon-based solid matter rate X was measured by weighing. c , as shown in Table 1C.

[0267] Comparative Example 7C

[0268] 4 g of the carbon fiber aggregate obtained in Example 1 used in Example 6C was replaced with 4 g of the carbon fiber aggregate in Comparative Example 1. Other conditions were the same as those in Example 6C. The microwave irradiation cracking product contained a large amount of black residue. The residual carbon-based solid matter rate X was measured by weighing. c , as shown in Table 1C.

[0269] Table 1C

[0270] Table 2C. Gas phase composition of cracking products

[0271] As shown in Table 1C, the final carbon-based solid matter residual rate (X) of polyolefins subjected to microwave pyrolysis using carbon fiber aggregates in an atmosphere containing carbon dioxide gas is shown in Table 1C. c ) are less than 3% (Example 6C and Example 7C), while the X of polyolefins cracked by microwave using traditional microwave heating materials is c are greater than 15% (Comparative Example 5C), and if only carbon fiber aggregates are used and microwave cracking of polyolefin is not performed in an atmosphere containing carbon dioxide, the final X c The results are all greater than 8% (Comparative Example 6C). It can be seen that the use of carbon fiber aggregates to perform microwave cracking of polyolefins in an atmosphere containing carbon dioxide gas can achieve more complete polyolefin cracking than other polyolefin cracking methods. In addition, since the temperature of the carbon fiber aggregate obtained in Comparative Example 1 can only reach 300°C under carbon dioxide microwave irradiation, only a small amount of polyolefin decomposes in a short time at this temperature. Therefore, the number of carbon fiber ends contained in each gram of carbon fiber aggregate must reach 1×10 6 More than one can achieve the effect of cracking polyolefins.

[0272] As shown in Table 2C, the gases produced by polyolefin cracking in Examples 6C and 7C, excluding unreacted carbon dioxide, primarily consist of carbon monoxide, hydrogen, methane, and ethylene. After separation, all of these gases can be used as chemical raw materials or energy fuels. The same experiments were performed on the samples obtained in Examples 2-5, yielding similar experimental phenomena and results.

[0273] Example of using microwaves to simultaneously recover and utilize VOCs and carbon dioxide:

[0274] The experimental data in the examples were measured using the following instruments and measurement methods:

[0275] In the embodiment, the collected cracked gas components are subjected to chromatographic analysis in the following manner:

[0276] The gas products collected after cracking were analyzed using a refinery gas analyzer (HP Agilent 7890A, equipped with 3 channels, including 1 FID and 2 TCDs (thermal conductivity detectors)) according to ASTM D1945-14. Hydrocarbons were analyzed on the FID channel. A TCD using a nitrogen 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 a carrier gas was used to detect CO, CO2, N2, and O2. For quantitative analysis, the response factor was determined by using an RGA (refinery gas analysis) calibration gas standard.

[0277] The raw materials of the embodiments of the invention are all commercially available.

[0278] VOCs gas was collected from several refineries and carbon dioxide was introduced into the gas to prepare five samples with a volume ratio of VOCs to carbon dioxide of 30:70, 40:60, 50:50, 60:40, and 70:30.

[0279] Example 6D

[0280] The carbon fiber aggregate surface obtained by 4g embodiment 1 is put into quartz jar, and vent holes are respectively arranged below and above quartz tube, so that the mixed gas of VOCs and carbon dioxide is entered by the lower port, and flows out from the upper port after contacting with carbon fiber microwave material (i.e. carbon fiber aggregate).First, purge quartz jar under pure carbon dioxide atmosphere, the air inside is excluded, and then sample 1 is passed through with a flow velocity of 40ml / min, and mixed gas 80g is passed through in total, and industrial microwave oven is used, and microwave irradiation is carried out with 700W microwave power, and the gas phase product produced after microwave cracking is collected using a gas collecting bag, and the gas phase composition of gas chromatographic analysis sample 1 and sample 1 cracking product is as shown in Table 1D.

[0281] The volume fraction of carbon dioxide in the cracking product gas of Sample 1 was reduced from 50% to 0%. At the same time, the other 19 VOCs were converted into four substances: methane (19.53 Vol%), ethylene (33.32 Vol%), hydrogen (31.07 Vol%) and carbon monoxide (16.08 Vol%), greatly reducing the difficulty of VOCs recycling.

[0282] The same experiment as above was carried out on the carbon fiber aggregates obtained in Examples 2-5, and similar experimental phenomena and results were obtained.

[0283] Table 1D. Gas phase composition of sample 1 and microwave plasma cracking products of sample 1

[0284] Example 7D

[0285] 12g of the carbon fiber aggregate obtained in Example 1 was placed in a 40cm long U-shaped tube. A mixed gas of VOCs and carbon dioxide was allowed to flow into one end of the U-shaped quartz tube, contact the carbon fiber microwave material, and then flow out from the other end. The U-shaped quartz tube containing the carbon fiber aggregate was placed in an industrial microwave oven. First, a pure carbon dioxide atmosphere was used to purge the quartz jar to remove the air inside. Then, Sample 2 was introduced at a flow rate of 20ml / min, for a total of 200g of mixed gas. Microwave irradiation was performed using an industrial microwave oven at a microwave power of 350W. A gas collection bag was used to collect the gaseous products produced after microwave pyrolysis. The gaseous phase compositions of Sample 2 and its pyrolysis products were analyzed by gas chromatography, as shown in Table 2D.

[0286] The volume fraction of carbon dioxide in the cracking product gas of sample 2 was reduced from 30% to 0%, while the other 17 VOCs were converted into four substances: methane (11.25 Vol%), ethylene (36.61 Vol%), hydrogen (32.44 Vol%) and carbon monoxide (19.7 Vol%).

[0287] Table 2D. Gas phase composition of sample 2 and its microwave plasma cracking products

[0288] Example 8D

[0289] The other conditions were the same as those in Example 6D, except that Sample 1 was replaced by Sample 3, and the mixture was introduced at a flow rate of 80 ml / min, with a total of 40 g of mixed gas introduced. The industrial microwave oven was used for microwave irradiation at a power of 1500 W, and the gas phase products produced after microwave pyrolysis were collected using a gas collection bag. The gas phase compositions of Sample 3 and the pyrolysis products of Sample 3 were analyzed by gas chromatography, as shown in Table 3D.

[0290] The volume fraction of carbon dioxide in the cracking product gas of sample 3 was reduced from 70% to 0%, while the other 22 VOCs were converted into four substances: methane (20.78Vol%), ethylene (20.52Vol%), hydrogen (23Vol%) and carbon monoxide (35.7Vol%).

[0291] Table 3D. Gas phase composition of sample 3 and microwave plasma cracking products of sample 3

[0292] Example 9D

[0293] The other conditions were the same as those in Example 7D, except that Sample 2 was replaced by Sample 4, and the mixture was introduced at a flow rate of 60 ml / min, with a total of 150 g of mixed gas introduced. The industrial microwave oven was used for microwave irradiation at a power of 900 W, and the gas phase products produced after microwave pyrolysis were collected using a gas collection bag. The gas phase compositions of Sample 4 and the pyrolysis products of Sample 4 were analyzed by gas chromatography, as shown in Table 4D.

[0294] The volume fraction of carbon dioxide in the cracking product gas of sample 4 was reduced from 40% to 0%, while the other 19 VOCs were converted into four substances: methane (18.69 Vol%), ethylene (30.45 Vol%), hydrogen (30.79 Vol%) and carbon monoxide (20.07 Vol%).

[0295] Table 4D. Gas phase composition of sample 4 and microwave plasma cracking products of sample 4

[0296] Example 10D

[0297] The other conditions were the same as those in Example 7D, except that Sample 2 was replaced by Sample 5, and the mixture was introduced at a flow rate of 120 ml / min, with a total of 240 g of mixed gas introduced. The industrial microwave oven was used for microwave irradiation at a power of 1500 W, and the gas phase products produced after microwave cracking were collected using a gas collection bag. The gas phase compositions of Sample 5 and the cracking products of Sample 5 were analyzed by gas chromatography, as shown in Table 5D.

[0298] The volume fraction of carbon dioxide in the cracking product gas of sample 5 was reduced from 60% to 0%, while the other 18 VOCs were converted into four substances: methane (19.29 Vol%), ethylene (21.78 Vol%), hydrogen (28.05 Vol%) and carbon monoxide (30.88 Vol%).

[0299] Table 5D. Gas phase composition of sample 5 and microwave plasma cracking products of sample 5

[0300] The experimental results in Tables 1D-5D show that through the plasma treatment generated by the carbon fiber aggregate, the carbon dioxide in the samples was fully consumed, and the complex VOCs components were converted into methane, ethylene, hydrogen, and carbon monoxide, greatly reducing the difficulty of VOCs recycling.

[0301] Comparative Example 5D

[0302] The 4 g of carbon fiber aggregate obtained in Example 1 used in Example 6D was replaced with 4 g of silicon carbide powder. Other conditions were the same as in Example 6D. A gas collecting bag was used to collect the gas phase products produced after microwave cracking, and the gas phase composition of sample 1 and the cracking product of sample 1 was analyzed by gas chromatography, as shown in Table 6D.

[0303] Since silicon carbide cannot generate microwave plasma and its heating temperature cannot exceed 1000°C, the volume fraction of carbon dioxide is only reduced by 10%. At the same time, the number of VOCs components increases from 19 to 25, making the VOCs components more complex and difficult to utilize. Therefore, carbon fiber aggregates are the key to achieving efficient recycling of VOCs and carbon dioxide at the same time.

[0304] Table 6D. Gas phase composition of sample 1 and silicon carbide microwave pyrolysis product of sample 1

[0305] Comparative Example 6D

[0306] In Example 6D, 50 vol% of the carbon dioxide in Sample 1 was replaced with 50 vol% nitrogen, with all other conditions remaining the same as in Example 6D. During the pyrolysis process, the absence of microwave plasma generated by carbon dioxide to consume the amorphous carbon formed by VOCs at high temperatures resulted in the amorphous carbon gradually wrapping around the ends of the carbon fibers, bonding them together. This rapidly reduced the number of carbon fiber ends available for plasma generation, ultimately leading to the failure of the carbon fiber aggregate. This demonstrates the importance of carbon dioxide in stabilizing the microwave pyrolysis system.

[0307] Comparative Example 7D

[0308] The 4 g of carbon fiber aggregate obtained in Example 1 used in Example 6D was replaced with 4 g of carbon fiber aggregate obtained in Comparative Example 1. Other conditions were the same as in Example 6D. A gas collecting bag was used to collect the gaseous products produced after microwave cracking, and the gas phase composition of Sample 1 and the cracking product of Sample 1 was analyzed by gas chromatography, as shown in Table 7D.

[0309] Since the carbon fiber aggregate obtained in Comparative Example 1 can only reach a temperature of 300°C under carbon dioxide microwave irradiation, carbon dioxide and VOCs cannot react at this temperature, so the products before and after pyrolysis in Table 7D do not change. It can be seen that the number of carbon fiber ends contained in each gram of carbon fiber aggregate must reach 1×10 6 More than one can deal with the effects of VOCs and carbon dioxide.

[0310] Table 7D. Gas phase composition of microwave pyrolysis products of carbon fiber aggregates of Sample 1 and Comparative Example 1

[0311] It should be noted that the embodiments described above are only used to explain the present invention and do not constitute any limitation of 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 function.

[0312] 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 conflict, the definitions in this specification shall prevail.

[0313] 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, the objects introduced by the prefix include 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 generally recognized in the art to be suitable for similar purposes.

[0314] The endpoints and any values ​​of the ranges disclosed in this application document are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and a separate point value, and the separate point values ​​can be combined with each other to obtain one or more new numerical ranges, 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.

[0315] In the context of this specification, any matters or items not mentioned are directly applicable to those known in the art without any changes except those explicitly stated.

[0316] Moreover, any embodiment described herein may be freely combined with one or more other embodiments described herein, and the technical solutions or technical ideas thus formed shall be deemed as part of the original disclosure or original record of the present invention, and shall not be regarded as new content that has not been disclosed or anticipated herein, 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 comprises a carbon fiber bundle formed by a plurality of carbon fibers and an optional single carbon fiber; the carbon fiber bundle is a carbon fiber bundle filament fixed together; and at least one fixed node is arranged on the carbon fiber bundle filament; 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 More than one.

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 , preferably 1×10 6 ~6×10 7 , more preferably 1×10 6 ~2×10 7 indivual.

3. The carbon fiber aggregate according to claim 1, characterized in that: 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. 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 includes both a single carbon fiber and a carbon fiber bundle; 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 the carbon fiber aggregate according to any one of claims 1 to 6, comprising: The carbon fiber bundle and the optional single carbon fiber are assembled in a random arrangement to obtain the carbon fiber aggregate; The method for preparing the carbon fiber bundle comprises fixing the carbon fiber bundle filaments together and providing at least one fixed node on the carbon fiber bundle filaments. When the carbon fiber bundle filaments are provided with two or more fixed nodes, the carbon fiber bundle filaments between adjacent fixed nodes are partially disconnected or completely disconnected.

8. The preparation method according to claim 7, 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 carbon fiber aggregate to graphite is (100:1) to (1:100), preferably (1:1) to (1:20), more preferably Select (1:1)~(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.

16. A method for simultaneously recovering biomass and carbon dioxide using microwaves, comprising: The biomass is brought into contact with the carbon fiber aggregate, and microwaves are applied to the biomass and the carbon fiber aggregate in an atmosphere of a gas containing carbon dioxide, so that the biomass reacts with the carbon dioxide and is converted into a gas product having carbon monoxide as a main component; The carbon fiber aggregate is 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.

17. The method according to claim 16, characterized in that: The weight ratio of the biomass to the carbon fiber aggregate is (1:100) to (100:1), preferably (1:50) to (50:1), and more preferably (1:20) to (20:1).

18. The method according to claim 16 or 17, characterized in that: The gas containing carbon dioxide comprises pure carbon dioxide gas or a mixed gas containing carbon dioxide; preferably, The carbon dioxide-containing mixed gas is a mixed gas of carbon dioxide and nitrogen and / or an inert gas and / or water vapor; more preferably, the inert gas is at least one of argon and helium; and / or, The volume fraction of carbon dioxide in the carbon dioxide mixed gas is 5% to 99.9%, preferably 10% to 99.9%, and most preferably 20% to 99.9%.

19. The method according to any one of claims 16 to 18, characterized in that: The power of the microwave is 1W to 100KW, preferably 200W to 50KW, most preferably 500W to 20KW; and / or, The microwave time is 0.1 to 200 min, preferably 0.5 to 150 min, most preferably 1 to 100 min; and / or, The temperature of the carbon fiber aggregate exceeds 1000°C, causing the biomass to pyrolyze.

20. The method according to any one of claims 16 to 19, characterized in that: The contacting mode between biomass and carbon fiber aggregate includes: placing biomass on carbon fiber aggregate, placing biomass in the cavity formed by carbon fiber aggregate, being covered by carbon fiber aggregate, being mixed by carbon fiber aggregate or a combination of one or more modes.

21. The method according to any one of claims 16 to 20, characterized in that: The biomass is various plants and animals and / or algae produced by photosynthesis, each containing cellulose, hemicellulose and lignin; preferably, The biomass is at least one of straw, bagasse, branches, leaves, wood chips, rice husks, straw, peanut shells, coconut shells, palm seed shells and corn cobs.

22. The method according to any one of claims 16 to 21, characterized in that The following steps are involved: a. Dehydrating the biomass; b. placing the dehydrated biomass and the carbon fiber assembly in a sealable reaction container, wherein the material of the reaction container is a microwave transparent material; c. introducing a gas containing carbon dioxide into the reaction vessel to replace the air; d. Start the microwave, place the reaction container under the microwave field to react, and collect the gas products generated by the reaction.

23. A method for simultaneously recovering polyolefin and carbon dioxide using microwaves, comprising: The polyolefin is brought into contact with the carbon fiber aggregate, and microwaves are applied to the polyolefin and the carbon fiber aggregate in an atmosphere of a gas containing carbon dioxide, so that the polyolefin reacts with the carbon dioxide to convert into a gas product having carbon monoxide as a main component; The carbon fiber aggregate is 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.

24. The method according to claim 23, characterized in that: The weight ratio of the polyolefin to the carbon fiber aggregate is (1:100) to (100:1), preferably (1:50) to (50:1), and more preferably (1:30) to (30:1).

25. The method according to claim 23 or 24, characterized in that: The gas containing carbon dioxide comprises pure carbon dioxide gas or a mixed gas containing carbon dioxide; preferably, The carbon dioxide-containing mixed gas is a mixed gas of carbon dioxide and nitrogen and / or an inert gas and / or water vapor; more preferably, the inert gas is at least one of argon and helium; and / or, The volume fraction of carbon dioxide in the carbon dioxide mixed gas is 5% to 99.9%, preferably 10% to 99.9%, and most preferably 20% to 99.9%.

26. The method according to any one of claims 23 to 25, characterized in that: The power of the microwave is 1W to 100KW, preferably 200W to 50KW, most preferably 500W to 20KW; and / or, The microwave time is 0.1 to 200 min, preferably 0.5 to 150 min, most preferably 1 to 100 min; and / or, The temperature of the carbon fiber aggregate exceeds 1000° C., causing polyolefin to decompose.

27. The method according to any one of claims 23 to 26, characterized in that: The contacting mode between the polyolefin and the carbon fiber aggregate includes: the polyolefin is placed on the carbon fiber aggregate, placed in the cavity formed by the carbon fiber aggregate, covered by the carbon fiber aggregate, and mixed with the carbon fiber aggregate, or a combination of one or more modes.

28. The method according to any one of claims 23 to 27, characterized in that: The polyolefin is a polyolefin prepared by homopolymerization or copolymerization of at least one of ethylene, propylene, butene, α-olefin, cycloolefin, 4-methyl-1-pentene, acrylic acid monomers, and a mixture of the polyolefins; preferably, The polyolefin is at least one of polyethylene, polypropylene, poly-1-butene, ethylene-vinyl acetate copolymer, polyolefin elastomer, cycloolefin homopolymer / copolymer, poly-4-methyl-1-pentene, ethylene-vinyl alcohol copolymer, and ethylene-acrylic acid copolymer.

29. The method according to any one of claims 23 to 28, characterized in that The specific steps include: a. Removing small molecules from polyolefins; b. placing the treated polyolefin and carbon fiber assembly in a sealable reaction container, wherein the reaction container is made of a microwave transparent material; c. introducing a gas containing carbon dioxide into the reaction vessel to replace the air; d. Start the microwave, place the reaction container under the microwave field to react, and collect the gas products generated by the reaction.

30. A method for simultaneously recovering VOCs and carbon dioxide using microwaves, comprising: A mixed gas containing carbon dioxide and VOCs is brought into contact with a carbon fiber aggregate, and under the condition of applying microwaves to the carbon fiber aggregate, the VOCs react with the carbon dioxide to be converted into cracked gas; The carbon fiber aggregate is 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.

31. The method according to claim 30, characterized in that: In the mixed gas containing carbon dioxide and VOCs, the content of VOCs is 10% to 90%, preferably 20% to 80%, more preferably 30% to 70%, based on the total volume of VOCs and carbon dioxide being 100%; and / or, The amount of the carbon fiber aggregate is greater than or equal to 1% of the total mass of the carbon dioxide and VOCs mixed gas to be treated, preferably greater than or equal to 3%, more preferably greater than or equal to 5%; and / or, The cracked gas contains methane, ethylene, hydrogen and carbon monoxide.

32. The method according to claim 30 or 31, characterized in that: The power of the microwave is 1W to 100KW, preferably 200W to 50KW, most preferably 500W to 20KW; and / or, The microwave time is 0.1 to 200 min, preferably 0.5 to 150 min, most preferably 1 to 100 min; and / or, The temperature of the carbon fiber aggregate exceeds 1000°C, causing VOCs to decompose.

33. The method according to any one of claims 30 to 32, characterized in that: The contacting method of the mixed gas containing carbon dioxide and VOCs with the carbon fiber aggregate includes: introducing carbon dioxide and VOCs into the reactor through the pores of the carbon fiber aggregate separately or simultaneously; preferably, Carbon dioxide and VOCs are introduced separately or simultaneously from the bottom of the carbon fiber aggregate, or the carbon fiber aggregate is placed in a U-shaped container, and carbon dioxide and VOCs are introduced separately or simultaneously from one end of the U-shaped container.

34. The method according to any one of claims 30 to 33, characterized in that: The VOCs are organic compounds with a boiling point of less than 260°C under standard atmospheric pressure; preferably, the VOCs include 2-methylpentane, hydrogen, n-hexane, 2,2,4-trimethylpentane, n-heptane, 2,3,4-trimethylpentane, methylcyclohexane, n-octane, n-nonane, n-decane, propane, isobutane, isobutene, n-butane, cyclopentane, isopentane, n-pentane, ethane, n-undecane, n-dodecane, methylcyclopentane, 3-methylpentane, 3-methylhexane, 2-methylhexane, One or more of 2,4-dimethylpentane, 2,2-dimethylbutane, 2,3-dimethylbutane, cyclohexane, 2-methylheptane, 3-methylheptane, 2,3-dimethylpentane, propylene, trans-2-butene, 1-butene, cis-2-butene, 1-pentene, cis-2-pentene, ethylene, acetylene, benzene, ethylbenzene, o-xylene, m-xylene, p-xylene, methane, toluene, m-ethyltoluene, p-ethyltoluene, o-ethyltoluene, styrene, isopropylbenzene, n-propylbenzene, 1,3,5-trimethylbenzene, 1,2,4-trimethylbenzene, 1,2,3-trimethylbenzene, m-diethylbenzene, p-diethylbenzene, acetone, 1,3-butadiene, and carbon monoxide.

35. The method according to any one of claims 30 to 34, characterized in that The following steps are involved: a. placing the carbon fiber aggregate in a sealable reaction container, wherein the material of the reaction container is a microwave transparent material; b. introducing carbon dioxide into the reaction container to replace the air, and then introducing carbon dioxide and VOCs; c. Start the microwave, place the reaction container under the microwave field to react, and collect the gas products generated by the reaction.

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