Method for simultaneously recycling polyolefin and carbon dioxide using microwaves and applications thereof

Abstract

This invention relates to the field of polyolefin processing technology and discloses a method for simultaneously recovering and utilizing polyolefins and carbon dioxide using microwaves. The method includes: contacting a polyolefin with a carbon fiber assembly; applying microwaves to the polyolefin and carbon fiber assembly in an atmosphere containing carbon dioxide; and reacting the polyolefin with the carbon dioxide to convert it into a gaseous product primarily composed of carbon monoxide. The carbon fiber assembly comprises multiple non-directionally arranged carbon fiber basic units, each of which is a bundle of single and / or multiple carbon fibers, with both ends of each carbon fiber along its length designated as carbon fiber ends. The number of carbon fiber ends per gram of the carbon fiber assembly is approximately 1 × 10⁻⁶. 6 The present invention utilizes carbon fiber assemblies to efficiently pyrolyze polyolefins, simultaneously and efficiently converting polyolefins and carbon dioxide into syngas with carbon monoxide as the main component.

Description

A method for simultaneously recycling polyolefins and carbon dioxide using microwaves and its applications. Technical Field

[0001] This invention relates to the field of polyolefin processing technology, specifically to a method for simultaneously recovering and utilizing polyolefins and carbon dioxide using microwaves, and its application. Background Technology

[0002] Polyolefin materials refer to thermoplastic polymers polymerized from ethylene, propylene, butene, or α-olefins, including polyethylene (PE), polypropylene (PP), and ethylene-vinyl acetate copolymer (EVA), which are commonly used in daily life. Currently, the global total production of polyolefins exceeds 220 million tons per year, widely used in medical and health, agriculture, transportation, electronics, construction and home furnishing, energy conservation and environmental protection, and new energy fields. It is the world's largest and most widely used polymer material. my country is the world's largest producer and consumer of polyolefins, with a total production capacity of 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 main chain of polyolefins, they have good chemical stability, making them difficult to degrade in natural environments, even under strong acid and alkali conditions. This makes waste polyolefins a significant source of environmental pollution, often manifesting as white pollution. Although polyolefins can be recycled through thermoplastic processing, the addition and use of additives during recycling prevents them from being permanently recycled through physical recycling. Ultimately, chemical recycling methods are still needed to process polyolefins into chemical raw materials or fuels. High-temperature pyrolysis is the most effective method for treating waste polyolefin materials, but tar and carbon deposits are easily formed during the pyrolysis process. This reduces the heat transfer efficiency of the pyrolysis furnace. If the tar in the pyrolysis products is not treated, it will gradually cool as it is carried through the pipeline, forming a viscous liquid that adheres to the pipeline, causing a series of problems that threaten the safety of pipelines and equipment, such as corrosion, scaling, and blockage.

[0003] Plasma is the fourth state of matter besides solid, liquid, and gas. Its characteristic is that its state is highly dependent on the electromagnetic field. Plasma is composed of unbound ions and free electrons, and its overall state is electrically neutral. Microwaves are electromagnetic waves with wavelengths between infrared and ultra-high frequency (UHF) radio waves. They have very strong penetrating power, with wavelengths between 1m and 1mm, corresponding to frequencies of 300GHz-300MHz. Microwave plasma technology is a technique for generating plasma through microwave irradiation, achieving energy conversion efficiencies of over 60% under non-equilibrium plasma conditions. Microwave plasma exhibits significant thermal effects. Our Chinese invention patent CN111100661A describes a porous composite material that can generate temperatures above 1000℃ under nitrogen atmosphere via microwave irradiation, thereby rapidly pyrolyzing polyolefins. However, the porous composite materials prepared by these two patents are rigid structural materials, exhibiting high brittleness and easy damage, which is detrimental to long-term use. Furthermore, they fail to address the problem of large amounts of tar and coke produced during polyolefin pyrolysis.

[0004] Extreme weather and the energy crisis are two major challenges facing humanity this century. As we all know, carbon dioxide is the primary greenhouse gas, and the occurrence of extreme weather events is mainly influenced by rising global carbon dioxide emissions. Therefore, carbon dioxide management has become a problem that requires attention and solutions from the entire society. The utilization of carbon dioxide can be divided into four main categories: chemical synthesis, fuel production, biological applications, and direct applications. Currently, the global annual carbon dioxide emissions are approximately 35 billion tons; however, the chemical industry, which consumes the largest amount of carbon dioxide, uses only about 220 million tons per year, a negligible amount compared to the total global emissions. Among the methods for converting carbon dioxide into energy fuels, the technology of reacting carbon dioxide with water to produce syngas has received 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.

[0005] Research has found that carbon dioxide can react with coke and tar at high microwave temperatures to transform into carbon monoxide. Therefore, if a microwave heating material that is not easily damaged and can generate plasma in a microwave field containing carbon dioxide is designed and synthesized, it is possible to reduce the amount of coke and tar produced by polyolefin pyrolysis, improve the utilization rate of polyolefin microwave pyrolysis, and simultaneously recover carbon dioxide, achieving efficient simultaneous recovery and utilization of both carbon dioxide and polyolefins, with broad application market potential. Summary of the Invention

[0006] To address the problems in existing technologies, this invention provides a method and its application for simultaneously recycling polyolefins and carbon dioxide using microwaves. This invention utilizes a carbon fiber assembly capable of generating high temperatures and plasma in a microwave field containing carbon dioxide gas to efficiently pyrolyze polyolefins. Taking advantage of the property that polyolefins produce coke and tar, which, along with carbon dioxide, are converted into carbon monoxide under microwave plasma and high temperatures, polyolefins and carbon dioxide are simultaneously and efficiently converted into syngas, primarily composed of carbon monoxide.

[0007] The carbon fiber assembly used in this invention is based on the following discovery by the inventors: Carbon fiber is a material that possesses both high strength and flexibility. Ordinary carbon fiber, such as T300 carbon fiber monofilament, has a tensile strength of up to 3500 MPa and a tensile modulus of up to 230 GPa. From a physical property perspective, while this solves the problems of high brittleness and easy damage, carbon fiber can both absorb and reflect microwaves. Furthermore, weaving carbon fiber only produces microwave-reflecting materials. Practical applications show that carbon fiber tends to reflect microwaves more. Currently, there is no precedent for using pure carbon fiber to generate plasma or other microwave heating materials through microwave irradiation. Through research, the inventors of this invention unexpectedly discovered that by controlling the number of carbon fiber ends per gram of the carbon fiber assembly, a carbon fiber assembly can be obtained that, although pure carbon fiber, can generate plasma and reach temperatures exceeding 1000°C under microwave irradiation.

[0008] The purpose of this invention is to provide a method for simultaneously recovering polyolefins and carbon dioxide using microwaves, comprising:

[0009] When polyolefins are brought into contact with carbon fiber assemblies, microwaves are applied to the polyolefin and carbon fiber assemblies in an atmosphere containing carbon dioxide. The polyolefins react with carbon dioxide to convert into gaseous products with carbon monoxide as the main component.

[0010] The carbon fiber assembly includes multiple non-directionally arranged carbon fiber basic units, which are single carbon fibers and / or carbon fiber bundles formed by multiple carbon fibers.

[0011] Taking the two ends along the length of each carbon fiber as carbon fiber ends, the number of carbon fiber ends contained in each gram of the carbon fiber assembly is approximately 1 × 10⁻⁶. 6 More than one per gram.

[0012] Through the above technical solution, the present invention brings polyolefin and carbon fiber assembly into contact, and applies microwaves to the polyolefin and carbon fiber assembly in an atmosphere containing carbon dioxide gas. The carbon fiber assembly generates high temperature and plasma in the microwave field containing carbon dioxide gas. Under the combined action of high temperature and plasma, polyolefin and carbon dioxide are converted into gaseous products (i.e., synthesis gas) with carbon monoxide as the main component.

[0013] In this invention, a gaseous product with carbon monoxide as the main component refers to a gaseous product containing 20% ​​or more, preferably 40% or more, and more preferably 50% or more, with the total volume of the gaseous product being 100% by volume.

[0014] In a preferred embodiment of the present invention, the carbon fiber assembly presents a two-dimensional or three-dimensional spatial structure.

[0015] In a preferred embodiment of the present invention, at least two or more adjacent carbon fiber base units are in contact with each other; preferably, the contact includes at least one of adjacent, overlapping and intersecting.

[0016] 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 ~6×10 8 pcs / g, preferably 1×10 6 ~6×10 7 1×10⁻⁶ units / g, more preferably 1×10⁻⁶ units / g 6 ~2×10 7 per g.

[0017] In a preferred embodiment of the present invention, the carbon fiber bundle is a bundle of carbon fiber filaments fixed together; the carbon fiber filaments are provided with at least one fixing node; more preferably,

[0018] 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;

[0019] When the carbon fiber bundle has two or more fixed nodes, the distance between adjacent fixed nodes is 1 to 50 mm, preferably 2 to 30 mm, and more preferably 5 to 20 mm; and the carbon fiber bundle between adjacent fixed nodes is in a disconnected state.

[0020] In a preferred embodiment of the present invention, the fixing includes binding and / or knotting, and the fixing node includes binding node and / or knotting point. More preferably, the knotting fixing is the fixing of carbon fiber bundles by themselves; and / or, the binding material for binding is carbon fiber bundles.

[0021] The raw materials used in the carbon fiber assembly of the present invention are commercially available. According to the present invention, the carbon fiber bundles can be made from various types of carbon fiber bundles in the prior art. In a preferred embodiment of the present invention, the carbon fiber bundles, the binding 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 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.

[0022] According to the present invention, the number of carbon fibers contained in each bundle of carbon fiber filaments can be selected in various 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.

[0023] According to the present invention, the carbon fiber assembly comprises a plurality of non-directionally arranged carbon fiber base units, wherein the carbon fiber base unit is a single carbon fiber and / or a carbon fiber bundle formed by multiple carbon fibers. In a preferred embodiment of the present invention, the carbon fiber base unit is a carbon fiber bundle formed by multiple carbon fibers, or the carbon fiber base unit simultaneously comprises a single carbon fiber and a carbon fiber bundle, or the carbon fiber base unit is a single carbon fiber. More preferably, the carbon fiber base unit is a carbon fiber bundle formed by multiple carbon fibers, or the carbon fiber base unit simultaneously comprises a single carbon fiber and a carbon fiber bundle. In this more preferred embodiment, the carbon fiber assembly is easier to use and recycle.

[0024] In a more preferred embodiment of the present invention, when the carbon fiber base unit comprises both single carbon fibers and carbon fiber bundles, with a total mass of 100 wt% for the carbon fiber assembly, the content of carbon fiber bundles in the carbon fiber assembly is 0.1-99.9 wt%, preferably 1-99 wt%; and / or, the length of each single carbon fiber is 0.1-30 mm, preferably 1-20 mm, more preferably 3-20 mm; and / or, the diameter of each single carbon fiber is 5-10 μm; and / or, the density is 1.5-2.0 g / cm³. 3 .

[0025] The method for preparing the carbon fiber assembly of the present invention includes:

[0026] The carbon fiber assembly is obtained by assembling the single carbon fiber and / or carbon fiber bundle in a non-directional arrangement; wherein the method for preparing the carbon fiber bundle includes fixing the carbon fiber bundle together and setting at least one fixing node on the carbon fiber bundle. When there are two or more fixing nodes on the carbon fiber bundle, the carbon fiber bundle between adjacent fixing nodes is partially or completely broken.

[0027] The aforementioned assembly refers to the aggregation of dispersed carbon fiber basic units together, which are physically mixed rather than chemically bonded to each other; for example, the aggregation of carbon fiber basic units is achieved by stacking or coiling, and preferably, at least two or more partially adjacent carbon fiber basic units are in contact with each other, more preferably, at least two or more partially adjacent carbon fiber basic units are in contact with each other in at least one manner including adjacency, overlap, and interpenetration.

[0028] In a preferred embodiment of the present invention, the fixing includes binding and / or knotting.

[0029] In a preferred embodiment of the invention, the disconnection includes cutting and / or shearing.

[0030] 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 0.1-30mm, preferably 1-20mm, and more preferably 3-20mm.

[0031] In a more preferred embodiment of the present invention, when there are two or more fixed nodes on the carbon fiber bundle, the spacing between adjacent fixed nodes is 1-50 mm, preferably 2-30 mm, and more preferably 5-20 mm.

[0032] The fixing includes binding and / or knotting, and the fixing nodes include binding nodes and / or knotting points. Preferably, knotting is done by tying the carbon fiber bundles themselves; and / or, binding is done by binding the carbon fiber bundles. More preferably, the knotting method is at least one of the following: single knot, square knot, boulin knot, Alpine butterfly knot, Alpine butterfly knot, double Alpine butterfly knot, black knot, clover knot, figure-eight single knot, and figure-eight connecting knot. For the knotting method, at least one of the following is preferred: single knot, square knot, Alpine butterfly knot, Alpine butterfly connecting knot, double Alpine butterfly knot, figure-eight single knot, and figure-eight connecting knot. More preferably, at least one of the following is preferred: single knot, square knot, Alpine butterfly knot, and figure-eight single knot.

[0033] The equipment used in the preparation method of this invention are all commonly used equipment.

[0034] The above-mentioned method for preparing carbon fiber assemblies directly uses high-strength carbon fiber as raw material. 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 is simple and easy to implement, and it is easy to achieve large-scale preparation.

[0035] In this invention, the weight ratio of polyolefin to carbon fiber aggregate is preferably (1:100) to (100:1), more preferably (1:50) to (50:1), and even more preferably (1:30) to (30:1).

[0036] Preferably, the gas containing carbon dioxide in this invention comprises pure carbon dioxide gas or a mixture containing carbon dioxide; more preferably,

[0037] The carbon dioxide mixture is a mixture of carbon dioxide and an inert gas and / or water vapor; more preferably, the inert gas is at least one of nitrogen, argon, and helium.

[0038] More preferably, the volume fraction of carbon dioxide in the carbon dioxide mixture is 5% to 99.9%, preferably 10% to 99.9%, and most preferably 20% to 99.9%.

[0039] 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.

[0040] According to the present invention, the microwave duration can be selected within a wide range. In a preferred embodiment of the present invention, the microwave duration is 0.1 to 200 min, preferably 0.5 to 150 min, and most preferably 1 to 100 min.

[0041] In this invention, the temperature of the carbon fiber assembly exceeds 1000°C, causing the polyolefin to decompose.

[0042] The contact between polyolefin and carbon fiber assembly can take various forms, as long as there is contact between the polyolefin and the carbon fiber assembly. Preferably, the contact between the polyolefin and the carbon fiber assembly includes one or more of the following methods: placing the polyolefin on the carbon fiber assembly, placing it in a cavity formed by the carbon fiber assembly, being covered by the carbon fiber assembly, and being blended with the carbon fiber assembly.

[0043] 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 monomer, as well as a mixture of the polyolefins.

[0044] The polyolefins described in this invention can be various types of polyethylene (PE), polypropylene (PP), poly-1-butene (PB-1), ethylene-vinyl acetate copolymer (EVA), polyolefin elastomer (POE), cyclic olefin homopolymer / copolymer (COP / COC), poly-4-methyl-1-pentene (PMP), ethylene-vinyl alcohol copolymer (EVOH), ethylene-acrylic acid copolymer (EAA), etc., prepared by homopolymerization or copolymerization of ethylene, propylene, butene, α-olefin, cyclic olefin, 4-methyl-1-pentene, acrylic acid monomer, etc., as well as mixtures of the above polyolefins.

[0045] Preferably, the polyolefin is at least one selected from polyethylene, polypropylene, poly-1-butene, ethylene-vinyl acetate copolymer, polyolefin elastomer, cyclic olefin homopolymer / copolymer, poly-4-methyl-1-pentene, ethylene-vinyl alcohol copolymer, and ethylene-acrylic acid copolymer.

[0046] In a preferred embodiment of the present invention, the method includes the following steps:

[0047] a. Perform small molecule removal treatment on polyolefins;

[0048] b. The treated polyolefin and carbon fiber assembly is placed in a sealable reaction container, and the reaction container is made of a microwave-transparent material.

[0049] c. Introduce carbon dioxide gas into the reaction vessel to replace the air;

[0050] d. Start the microwave, place the reaction vessel under the microwave field to carry out the reaction, and collect the gaseous products generated by the reaction.

[0051] A method for simultaneously recycling polyolefins and carbon dioxide using microwaves includes the following steps:

[0052] a. Polyolefins are subjected to small molecule removal treatment at 50℃-200℃ for 1min-240min. The small molecule removal equipment can be commercially available drying equipment, such as blower dryer, microwave oven, thermal radiation instrument, etc. Small molecule removal treatment can also be carried out by sun exposure, air drying, etc., so that the polyolefin does not produce more than 1% mass thermal weight loss within 10 minutes at 200℃.

[0053] b. Place the polyolefin and the carbon fiber assembly together in any manner, so that the polyolefin comes into contact with the carbon fiber assembly;

[0054] c. Passing pure carbon dioxide or a mixture of carbon dioxide and one or more of the following gases into the reaction system will displace the air;

[0055] d. Start the microwave and collect the gaseous products generated by the reaction.

[0056] The microwave field in the method of the present invention can be any microwave device in the prior art, such as a household microwave oven, industrial microwave equipment (such as a microwave pyrolysis reactor), etc.

[0057] According to the present invention, microwave transparent material refers to a material through which microwaves can penetrate the wall of the reaction vessel and radiate onto the sample.

[0058] In the method of the present invention, the device for placing or supporting the polyolefin and carbon fiber assembly can be selected from various containers or pipes that are microwave-penetrable and resistant to temperatures above 1200°C, such as quartz crucibles, quartz reactors, quartz tubes, alumina crucibles, alumina reactors, alumina tubes, etc.

[0059] The method of the present invention involves the gasification of polyolefins after pyrolysis, and the gas obtained after pyrolysis can be collected for subsequent processing, such as separation of the gas for use as fuel or as a raw material for subsequent reactions and production in the chemical industry.

[0060] The 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: a quartz crucible carrying waste plastic and porous composite materials is placed in a vacuum bag in a nitrogen-protected glove box and sealed. After the reaction under microwave, the crucible is unscrewed through the vacuum bag, and a syringe is used to puncture the vacuum bag to take a sample. If an industrial microwave oven with an inlet and an outlet (such as a microwave pyrolysis reactor) is used, the gas collection method is as follows: the reaction process is purged with nitrogen, and the outlet is sampled and collected using a gas collection bag.

[0061] A second aspect of the present invention is to provide an application of the method for simultaneously recovering polyolefins and carbon dioxide using microwaves according to the first aspect in the recovery of polyolefins.

[0062] The carbon fiber assembly described in this invention, a method for simultaneously recovering polyolefins 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. This invention obtains a carbon fiber assembly by controlling the number of carbon fiber ends per gram of the assembly. Although this assembly is pure carbon fiber, it can generate plasma and reach temperatures exceeding 1000°C under microwave irradiation. This overcomes the problems of brittleness and easy damage in existing porous composite materials. Furthermore, the carbon fiber assembly of this invention uses simple raw materials, is easy to prepare, and has extremely high application value.

[0063] This invention uses a durable carbon fiber assembly that can generate plasma in a microwave field containing carbon dioxide. This reduces the amount of coke and tar produced by polyolefin pyrolysis, improves the utilization rate of polyolefin microwave pyrolysis, and simultaneously recovers carbon dioxide, achieving efficient recovery and utilization of both carbon dioxide and polyolefin. This invention has a wide range of applications. Attached Figure Description

[0064] Figure 1 is a photograph of the morphology of the carbon fiber assembly in Embodiment 1 of the present invention; wherein the basic unit of the carbon fiber is a carbon fiber bundle prepared from carbon fiber filaments. Detailed Implementation

[0065] The present invention will now be described in detail with reference to specific embodiments. It should be noted that the following embodiments are only used to further illustrate the present invention and should not be construed as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the content of the present invention are still within the scope of protection of the present invention.

[0066] The experimental data in the examples were measured using the following instruments and methods:

[0067] In this embodiment, the collected syngas components were subjected to chromatographic analysis as follows:

[0068] The gaseous products collected after pyrolysis were analyzed using a refinery gas analyzer (HPAgilent 7890A, configured with 3 channels, including 1 FID and 2 TCDs (thermal conductivity detectors)) according to ASTM D1945-14. Hydrocarbons were analyzed in the FID channel. A TCD using nitrogen as the carrier gas was applied to determine the hydrogen content, due to the small difference in conductivity between hydrogen and helium. Another TCD using helium as the carrier gas was used to detect CO, CO2, N2, and O2. For quantitative analysis, the response factor was determined using an RGA (Refinery Gas Analysis) calibration gas standard.

[0069] In the example, the residual rate of carbon-based solids after polyolefin pyrolysis, X, is...c The content was analyzed by gravimetric method:

[0070] Weigh out the mass of the polyolefin after drying as M1, and weigh out the mass of the residual solids after the polyolefin is cracked as M2.

[0071] Residual carbon-based solids after polyolefin pyrolysis X c =M2 / M1×100%

[0072] The raw materials used in the embodiments of the invention are all commercially available.

[0073] The number of carbon fiber ends contained in each gram of the carbon fiber assembly was obtained through theoretical calculation, specifically as follows:

[0074] (1) When the basic unit of the carbon fiber assembly is a single carbon fiber, the formula for the number of carbon fiber ends contained in each gram of the carbon fiber assembly is as follows:

[0075]

[0076] N is the number of carbon fiber ends per gram of the carbon fiber aggregate (unit: ends / g), and ρ is the carbon fiber density (unit: g / cm³). 3 ), where d is the diameter of the carbon fiber (unit: μm) and L is the length of the carbon fiber filament (unit: mm).

[0077] (2) When the carbon fiber basic unit of the carbon fiber assembly is a carbon fiber bundle prepared from carbon fiber filaments with one or more knots, the method for calculating the number of carbon fiber ends contained in each gram of the carbon fiber assembly is as follows:

[0078] N=[(n-1)×2×t+2]×k / m

[0079] N is the number of carbon fiber ends contained in each gram of the carbon fiber assembly (unit: ends / g), n is the number of knots on the carbon fiber bundle; t is the proportion of long carbon fiber bundles cut between knots, k is the number of carbon fibers in the carbon fiber bundle, and m is the total mass of the carbon fiber bundle (unit: g).

[0080] Taking the calculation method described in Example 1 as an example, a 5000mm long bundle of T300 carbon fiber 12K filaments can be knotted by itself (single knot) at a knotting interval of 10mm, resulting in 499 knots. If the carbon fiber is cut two-thirds of the way from the midpoint between the two ends of the knot, [(499-1)×2×2 / 3+2)]×12000=7992000 carbon fiber ends can be generated. The knots formed by the single knots are loop-shaped without ends. The mass of the 5000mm long bundle of T300 carbon fiber 12K filaments 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 per g.

[0081] (3) For carbon fiber assemblies prepared from carbon fiber bundles having one or more fixed nodes and / or binding nodes, the method for calculating the number of carbon fiber ends per gram of the carbon fiber assembly is as follows:

[0082] N=[(n-1)×2×t×k+2k+c1×n1×k1)] / m

[0083] N is the number of carbon fiber ends contained in each gram of the carbon fiber assembly (unit: number / g), n is the total number of fixed nodes formed by knotting and bundling on the carbon fiber bundle; t is the proportion of long carbon fiber bundles cut at fixed nodes, and k is the number of carbon fibers in the long carbon fiber bundle.

[0084] c1 is the number of ends of each bundle at each fixed node when the fixed node is a binding node; n1 is the number of binding nodes; k1 is the number of carbon fibers containing carbon fiber bundles in the binding material of the binding node.

[0085] m is the total mass of the carbon fiber bundle (unit: g).

[0086] (4) When the carbon fiber basic unit of the carbon fiber assembly includes both single carbon fibers and carbon fiber bundles, the method for calculating the number of carbon fiber ends per gram of the carbon fiber assembly is as follows:

[0087]

[0088] N represents the number of carbon fiber ends per gram of the carbon fiber assembly (unit: ends / g); n represents the total number of fixed nodes formed by knotting and binding on the carbon fiber bundles in the carbon fiber assembly based on carbon fiber bundles as basic units; t represents the proportion of long carbon fiber bundles cut at fixed nodes in the carbon fiber assembly based on carbon fiber bundles as basic units; k represents the number of carbon fibers in the long carbon fiber bundles in the carbon fiber assembly based on carbon fiber bundles as basic units; c1 represents the number of ends of each binding material at each fixed node when the fixed node is a binding node; n1 represents the number of binding nodes in the carbon fiber assembly based on carbon fiber bundles as basic units; k1 represents the number of carbon fibers containing carbon fiber bundles in the binding material of the binding nodes in the carbon fiber assembly based on carbon fiber bundles as basic units; ρ represents the carbon fiber density in the carbon fiber assembly based on a single carbon fiber as a basic unit (unit: g / cm³). 3 ), d is the diameter of the carbon fiber in the part of the carbon fiber assembly constructed with a single carbon fiber as the basic unit (unit: μm), L is the length of the carbon fiber filament in the part of the carbon fiber assembly constructed with a single carbon fiber as the basic unit (unit: mm); m1 is the total mass of the part of the carbon fiber assembly constructed with carbon fiber bundles as the basic unit (unit: g), and m2 is the total mass of the part of the carbon fiber assembly constructed with a single carbon fiber as the basic unit (unit: g).

[0089] Taking the calculation method described in Example 5 as an example. A 2500mm long bundle of T300 carbon fiber 12K filaments can be knotted by itself (single knot) at a knotting interval of 10mm, resulting in 249 knots. Two-thirds of the carbon fiber bundle is cut off at a distance of 5mm from each knotting point, producing [(249-1)×2×2 / 3+2)]×12000=3992000 carbon fiber ends. The knots formed by the single knots are loop-shaped and endless. The mass of the 2500mm long T300 carbon fiber 12K bundle is 1.98g; (The last sentence appears to be incomplete and possibly refers to a different calculation method.) 3 The mass of a single T700 carbon fiber is 3g, therefore the number of carbon fiber ends contained in each gram of the carbon fiber assembly described in Example 5 is .

[0090]

[0091] Temperature detection method: Immediately after microwave irradiation, a metal thermocouple is inserted into the reaction vessel and brought into contact with the carbon fiber assembly to measure the temperature.

[0092] Preparation of carbon fiber assemblies:

[0093] Example 1

[0094] Take a 5000mm long T300 carbon fiber 12K bundle (3.96g, Weihai Guangwei Composite Materials Group Co., Ltd.), and tie it using a single-knot method at 10mm intervals, resulting in 499 knots. Cut two-thirds of the carbon fiber bundle at a distance of 5mm from each knot to form a carbon fiber assembly. Bundle this material and place it in a quartz jar. Each gram of carbon fiber assembly contains approximately 2 × 10⁻⁶ carbon fiber ends. 6 The material can generate plasma and reach an equilibrium temperature of 1200°C under a pure carbon dioxide atmosphere by microwave irradiation with 900W.

[0095] Comparative Example 1

[0096] Take a 5000mm long T300 carbon fiber 12K bundle (3.96g, Weihai Guangwei Composite Materials Group Co., Ltd.), and tie it using a single-knot method at a knot spacing of 250mm, resulting in 19 knots. Cut two-thirds of the carbon fiber bundle at a distance of 125mm from each knot to form a carbon fiber assembly. Bundle the assembly and place it in a quartz jar. Each gram of carbon fiber assembly contains approximately 7.9 × 10⁻⁶ carbon fiber ends. 4 The material was irradiated with a 900W microwave in a pure carbon dioxide atmosphere, and the equilibrium temperature of the material could only reach 300℃.

[0097] Example 2

[0098] Take 4g of a single T300 carbon fiber (short carbon fiber, density 1.76g / cm³) with a length of 3mm and a diameter of 7μm. 3 (Weihai Guangwei Composite Materials Group Co., Ltd.), the carbon fibers are randomly stacked in a quartz jar, and the number of carbon fiber ends contained in each gram of carbon fiber aggregate is approximately 9.8 × 10⁻⁶. 6 The material can generate plasma and reach an equilibrium temperature of 1400℃ by irradiation with 1200W microwaves in a pure carbon dioxide atmosphere.

[0099] Comparative Example 2

[0100] Take 4g of a single T300 carbon fiber (short carbon fiber, density 1.76g / cm³) with a length of 60mm and a diameter of 7μm. 3 (Weihai Guangwei Composite Materials Group Co., Ltd.), the carbon fibers are randomly stacked in a quartz jar, and the number of carbon fiber ends contained in each gram of carbon fiber aggregate is approximately 4.9 × 10⁻⁶. 5 The material was irradiated with 1200W microwaves in a pure carbon dioxide atmosphere, and the material temperature could only reach the equilibrium temperature of 600℃.

[0101] Example 3

[0102] Take a 5600mm long T700 carbon fiber 12K bundle (4.48g, 7μm diameter, Weihai Guangwei Composite Materials Group Co., Ltd.), and tie it using a single-knot method at a knot spacing of 14mm, resulting in 399 knots. Cut two-thirds of the carbon fiber bundle 7mm from the knot point to form a carbon fiber assembly. Bundle this material and place it in a quartz jar. Each gram of carbon fiber assembly contains approximately 1.4 × 10⁻⁶ carbon fiber ends. 6 The material can generate plasma and reach an equilibrium temperature of 1100°C by microwave irradiation at 700W in a mixed gas atmosphere of carbon dioxide and water vapor with a volume ratio of 90:10.

[0103] Comparative Example 3

[0104] Take a 5000mm long T700 carbon fiber 12K bundle (4.0g, Weihai Guangwei Composite Materials Group Co., Ltd.), and tie it using a single-knot method at a knot spacing of 250mm, resulting in 19 knots. Cut two-thirds of the carbon fiber bundle at a distance of 125mm from each knot to form a carbon fiber assembly. Bundle the assembly and place it in a quartz jar. Each gram of carbon fiber assembly contains approximately 7.8 × 10⁻⁶ carbon fiber ends. 4 The material was irradiated with 700W microwaves in a mixed gas atmosphere of 90:10 volume ratio of carbon dioxide and water vapor, and the material equilibrium temperature could only reach 100℃.

[0105] Example 4

[0106] Take 6g of a single T700 carbon fiber (short carbon fiber, density 1.8g / cm³) with a length of 5mm and a diameter of 7μm. 3 (Weihai Guangwei Composite Materials Group Co., Ltd.), the carbon fibers are randomly stacked in a quartz jar, and the number of carbon fiber ends contained in each gram of carbon fiber aggregate is approximately 5.8 × 10⁻⁶. 6 The material can generate plasma and reach an equilibrium temperature of 1050°C by microwave irradiation at 1200W in a mixed gas atmosphere of carbon dioxide and water vapor with a volume ratio of 30:70.

[0107] Comparative Example 4

[0108] Take 6g of a single T700 carbon fiber (short carbon fiber, density 1.8g / cm³) with a length of 35mm and a diameter of 7μm. 3 (Weihai Guangwei Composite Materials Group Co., Ltd.), the carbon fibers are randomly stacked in a quartz jar, and the number of carbon fiber ends contained in each gram of carbon fiber aggregate is approximately 8.3 × 10⁻⁶. 5The 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 material equilibrium temperature could only reach 900℃.

[0109] Example 5

[0110] Take a 2500mm long T300 carbon fiber 12K bundle (1.98g, Weihai Guangwei Composite Materials Group Co., Ltd.), and tie it using a single-knot method at 10mm intervals, resulting in 249 knots. Cut two-thirds of the carbon fiber bundle 5mm from each knot. Take 3g of a 5mm long, 7μm diameter T700 single carbon fiber (short carbon fiber, density 1.8g / cm³). 3 (Weihai Guangwei Composite Materials Group Co., Ltd.) The carbon fiber is mixed with knotted carbon fiber bundles to form carbon fiber assemblies, which are then randomly stacked in a quartz jar. The number of carbon fiber ends per gram of carbon fiber assembly is approximately 4.3 × 10⁻⁶. 6 The material can generate plasma and reach an equilibrium temperature of 1280°C under a pure carbon dioxide atmosphere by microwave irradiation with 900W.

[0111] The carbon fiber assemblies prepared in Examples 1-5 each contain more than 1 × 10⁻⁶ carbon fiber ends per gram of carbon fiber assembly. 6 The carbon fiber aggregates prepared in Examples 1-4 contain less than 1 × 10⁻⁶ carbon fiber ends per gram. Under microwave irradiation in a pure carbon dioxide and mixed gas (carbon dioxide and water vapor) atmosphere, sufficient plasma can be generated, resulting in a material equilibrium temperature greater than 1000℃. 6 The material's equilibrium temperature is less than 900℃ because it cannot generate sufficient plasma under microwave irradiation in a pure carbon dioxide and mixed gas (carbon dioxide and water vapor) atmosphere.

[0112] Simultaneous recycling of polyolefins and carbon dioxide using microwaves:

[0113] Example 6

[0114] Polyethylene granules, polypropylene flakes from discarded lunch boxes, poly-1-butene granules, and ethylene-vinyl acetate copolymer from discarded shoe soles were subjected to small molecule removal treatment at 200°C for 5 hours using a blower dryer. 2g of each of the small molecule-removed polyethylene granules, polypropylene flakes from discarded lunch boxes, poly-1-butene granules, and ethylene-vinyl acetate copolymer from discarded shoe soles were placed on the surface of 4g of the carbon fiber aggregate obtained in Example 1. The polyolefin and carbon fiber aggregate were then placed in a quartz jar. Under a pure carbon dioxide atmosphere, the materials were microwaved at 700W for 10 minutes using an industrial microwave oven. All materials vaporized and decomposed after microwave irradiation, leaving only a small amount of black residue. The carbon-based solid residue rate X was measured by weighing. c As shown in Table 1, the composition of the obtained gaseous products is shown in Table 2.

[0115] Example 7

[0116] Polyethylene granules, polypropylene sheets from discarded lunch boxes, poly-1-butene granules, and ethylene-vinyl acetate copolymer from discarded shoe soles were subjected to small molecule removal treatment for 30 minutes using an industrial microwave oven at 350W under air purging. 64g of each of the de-moleculeed polyethylene granules, polypropylene sheets from discarded lunch boxes, poly-1-butene granules, and ethylene-vinyl acetate copolymer from discarded shoe soles were then mixed with 32g of the carbon fiber aggregate obtained in Example 1. The polyolefin and carbon fiber aggregate were then placed in a quartz jar. Under a mixed gas atmosphere of 80:20 carbon dioxide to water vapor, the mixture was microwave irradiated for 10 minutes using an industrial microwave oven at 2000W. All materials were vaporized and decomposed after microwave irradiation, leaving only a small amount of black residue. The carbon-based solid residue rate X was measured by weighing. c As shown in Table 1, the composition of the obtained gaseous products is shown in Table 2.

[0117] Comparative Example 5

[0118] In Example 6, the 4g carbon fiber aggregate obtained in Example 1 was replaced with 4g silicon carbide powder, and other conditions were the same as in Example 6. The microwave irradiation pyrolysis products contained a large amount of black residue, and the carbon-based solid residue rate X was measured by weighing. c As shown in Table 1.

[0119] Comparative Example 6

[0120] In Example 6, the gaseous environment for microwave irradiation was replaced with pure nitrogen instead of pure carbon dioxide, while other conditions remained the same as in Example 6. The microwave irradiation pyrolysis products contained a large amount of black residue, and the carbon-based solid residue rate X was measured by weighing. c As shown in Table 1.

[0121] Comparative Example 7

[0122] In Example 6, 4g of the carbon fiber assembly obtained in Example 1 was replaced with 4g of the carbon fiber assembly from Comparative Example 1. All other conditions remained the same as in Example 6. The microwave irradiation pyrolysis products contained a large amount of black residue. The carbon-based solid residue rate X was measured by weighing. c As shown in Table 1.

[0123] Table 1

[0124]

[0125] Table 2. Gas phase composition of pyrolysis products

[0126]

[0127]

[0128] As shown in Table 1, the final carbon-based solid residue (X) of polyolefins subjected to microwave pyrolysis using carbon fiber assemblies in an atmosphere containing carbon dioxide gas is shown. c The content of X in microwave-induced pyrolysis of polyolefins using conventional microwave heating materials was less than 3% (Examples 6 and 7). c All were greater than 15% (Comparative Example 5), and if only carbon fiber assemblies were used, and microwave pyrolysis of polyolefins was not performed in an atmosphere containing carbon dioxide, the final X c All were greater than 8% (Comparative Example 6). This demonstrates that microwave pyrolysis of polyolefins using carbon fiber assemblies in a carbon dioxide atmosphere achieves more complete pyrolysis compared to other polyolefin pyrolysis methods. Furthermore, since the carbon fiber assembly obtained in Comparative Example 1 only reached a temperature of 300°C under carbon dioxide microwave irradiation, and at this temperature only a small amount of polyolefin decomposed in a short time, it is evident that the number of carbon fiber ends per gram of carbon fiber assembly needs to reach 1×10⁻⁶. 6 Only when the number of particles per gram is above a certain level can the effect of cracking polyolefins be achieved.

[0129] As shown in Table 2, the main components of the gases produced by the cracking of polyolefins in Examples 6 and 7, excluding incompletely reacted carbon dioxide, are carbon monoxide, hydrogen, methane, and ethylene, all of which can be used as chemical raw materials or energy fuels after separation. Similar experimental phenomena and results were obtained by performing the same experiments on the samples obtained in Examples 2-5.

[0130] It should be noted that the embodiments described above are only for explaining the present invention and do not constitute any limitation on 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 terms, not limiting terms. Modifications can be made to the present invention within the scope of the claims, and revisions can be made to the present invention without departing from the scope and spirit of the present invention. Although the present invention described herein relates to specific methods, materials, and embodiments, it does not mean that the present invention is limited to the specific examples disclosed herein; on the contrary, the present invention can be extended to all other methods and applications with the same function.

[0131] 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 commonly understood by those skilled in the art. In case of conflict, the definitions in this specification shall prevail.

[0132] When this specification uses the prefixes “known to those skilled in the art,” “prior art,” or similar terms to derive materials, substances, methods, steps, apparatus, or components, the objects derived from such prefixes cover those commonly used in the art at the time of this application, but also include those that are not currently commonly used but will become generally recognized in the art as suitable for similar purposes.

[0133] The endpoints and any values ​​of the ranges disclosed in this application are not limited to the precise ranges or values; such ranges or values ​​should be understood to include values ​​close to them. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein. In principle, various technical solutions can be combined with each other to obtain new technical solutions, which should also be considered as specifically disclosed herein.

[0134] In the context of this specification, except where expressly stated otherwise, any matters or issues not mentioned shall apply directly to those known in the art without any modification.

[0135] Furthermore, any implementation described herein can be freely combined with one or more other implementations described herein, and the resulting technical solutions or technical ideas shall be regarded as part of the original disclosure or original record of the present invention, and should not be regarded as new content not disclosed or anticipated herein, unless those skilled in the art consider the combination to be obviously unreasonable.

Claims

1. A method for simultaneously recovering polyolefins and carbon dioxide using microwaves, comprising: Polyolefins are brought into contact with carbon fiber assemblies. Microwaves are applied to the polyolefin-carbon fiber assemblies in a carbon dioxide atmosphere, causing the polyolefins to react with the carbon dioxide and convert into a gaseous product primarily composed of carbon monoxide. The carbon fiber assemblies comprise multiple non-directionally arranged carbon fiber basic units, each of which is a single carbon fiber and / or a bundle of multiple carbon fibers. The ends of each carbon fiber along its length are designated as carbon fiber ends, and the number of carbon fiber ends per gram of the carbon fiber assembly is 1 × 10⁻⁶. 6 ~6×10 8 per g.

2. The method according to claim 1, characterized in that: The carbon fiber assembly exhibits a two-dimensional or three-dimensional spatial structure; and / or, at least two or more adjacent carbon fiber base units are in contact with each other; and / or, based on the number of carbon fiber ends, each gram of the carbon fiber assembly contains 1 × 10⁻⁶ carbon fiber ends. 6 ~6×10 7 per g.

3. The method according to claim 1, characterized in that: The number of carbon fiber ends per gram of the carbon fiber assembly is 1 × 10⁻⁶. 6 ~2×10 7 per g.

4. The method according to claim 1, characterized in that: The carbon fiber bundle consists of carbon fiber strands fixed together; each carbon fiber strand has at least one fixed node.

5. The method according to claim 4, characterized in that: When there is only one fixed node on the carbon fiber bundle, the length of the carbon fiber bundle is 0.1~30 mm; when there are two or more fixed nodes on the carbon fiber bundle, the distance between adjacent fixed nodes is 1~50 mm; and the carbon fiber bundle between adjacent fixed nodes is in a disconnected state.

6. The method according to claim 4, characterized in that: When there is only one fixed node on the carbon fiber bundle, the length of the carbon fiber bundle is 1~20 mm; when there are two or more fixed nodes on the carbon fiber bundle, the distance between adjacent fixed nodes is 2~30 mm; and the carbon fiber bundle between adjacent fixed nodes is in a disconnected state.

7. The method according to claim 4, characterized in that: When there is only one fixed node on the carbon fiber bundle, the length of the carbon fiber bundle is 3~20mm; when there are two or more fixed nodes on the carbon fiber bundle, the distance between adjacent fixed nodes is 5~20mm; and the carbon fiber bundle between adjacent fixed nodes is in a disconnected state.

8. The method according to claim 4, characterized in that: The fixing includes binding and / or knotting, and the fixing nodes include binding nodes and / or knotting points.

9. The method according to claim 8, characterized in that: The knotting and fixing are achieved by the carbon fiber bundles being fixed by their own knotting; and / or, the binding material for the binding is carbon fiber bundles.

10. The method according to claim 9, characterized in that: The carbon fiber bundles, binding carbon fiber bundles, and 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.

11. The method according to claim 9, characterized in that: The carbon fiber bundles, binding carbon fiber bundles, and knotting carbon fiber bundles are independently selected from at least one of the following types of carbon fiber bundles: T300, T700, and T800.

12. The method according to claim 9, characterized in that: The carbon fiber bundles, binding carbon fiber bundles, and knotting carbon fiber bundles are independently selected from at least one of the following types of carbon fiber bundles: T300 and T700.

13. The method according to claim 9, characterized in that: Each bundle of carbon fiber contains 1K-48K carbon fibers.

14. The method according to claim 9, characterized in that: Each bundle of carbon fiber contains 1K, 3K, 6K, 12K, 24K, or 48K carbon fibers.

15. The method according to claim 9, characterized in that: Each bundle of carbon fiber contains 12K or 24K carbon fibers.

16. The method according to claim 1, characterized in that: The carbon fiber base unit is a carbon fiber bundle formed by multiple carbon fibers, or the carbon fiber base unit includes both a single carbon fiber and a carbon fiber bundle, or the carbon fiber base unit is a single carbon fiber.

17. The method according to claim 16, characterized in that: When the carbon fiber base unit contains both single carbon fibers and carbon fiber bundles, the total mass of the carbon fiber assembly is 100wt%, the content of carbon fiber bundles in the carbon fiber assembly is 0.1-99.9wt%, and / or, the length of each fiber of the single carbon fiber is 0.1-30 mm.

18. The method according to claim 16, characterized in that: When the carbon fiber base unit contains both single carbon fibers and carbon fiber bundles, the total mass of the carbon fiber assembly is 100 wt%, the content of carbon fiber bundles in the carbon fiber assembly is 1-99 wt%, and / or, the length of each fiber of the single carbon fiber is 1-20 mm.

19. The method according to claim 16, characterized in that: The length of each individual carbon fiber is 3-20 mm.

20. The method according to claim 1, characterized in that: The weight ratio of polyolefin to carbon fiber aggregate is (1:100) to (100:1).

21. The method according to claim 1, characterized in that: The weight ratio of polyolefin to carbon fiber aggregate is (1:50) to (50:1).

22. The method according to claim 1, characterized in that: The weight ratio of polyolefin to carbon fiber aggregate is (1:30) to (30:1).

23. The method according to claim 1, characterized in that: Gases containing carbon dioxide include pure carbon dioxide gas or mixtures containing carbon dioxide.

24. The method according to claim 23, characterized in that: The carbon dioxide-containing gas mixture is a mixture of carbon dioxide with an inert gas and / or water vapor.

25. The method according to claim 24, characterized in that: The inert gas is at least one of nitrogen, argon, and helium.

26. The method according to claim 23, characterized in that: The volume fraction of carbon dioxide in the carbon dioxide mixture is 5% to 99.9%.

27. The method according to claim 23, characterized in that: The volume fraction of carbon dioxide in the carbon dioxide mixture is 10% to 99.9%.

28. The method according to claim 23, characterized in that: The volume fraction of carbon dioxide in the carbon dioxide mixture is 20% to 99.9%.

29. The method according to claim 1, characterized in that: The microwave power is 1W to 100KW; and / or the microwave duration is 0.1 to 200min; and / or the temperature of the carbon fiber assembly exceeds 1000℃, causing the polyolefin to decompose.

30. The method according to claim 1, characterized in that: The power of the microwave is 200W to 50KW; and / or the microwave duration is 0.5 to 150min.

31. The method according to claim 1, characterized in that: The power of the microwave is 500W to 20KW; and / or the microwave duration is 1 to 100min.

32. The method according to claim 1, characterized in that: The contact methods between polyolefins and carbon fiber assemblies include one or more of the following: polyolefins are placed on the carbon fiber assemblies, placed in cavities formed by the carbon fiber assemblies, covered by the carbon fiber assemblies, and blended with the carbon fiber assemblies.

33. The method according to claim 1, 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, and acrylic acid monomer, as well as a mixture of the polyolefins.

34. The method according to claim 1, characterized in that: The polyolefin is at least one of polyethylene, polypropylene, poly-1-butene, ethylene-vinyl acetate copolymer, polyolefin elastomer, cyclic olefin homopolymer / copolymer, poly-4-methyl-1-pentene, ethylene-vinyl alcohol copolymer, and ethylene-acrylic acid copolymer.

35. The method according to claim 1, characterized in that... Specifically, the following steps are included: a. Remove small molecules from the polyolefin; b. Place the treated polyolefin and carbon fiber assembly in a sealable reaction container, wherein the reaction container is made of microwave-transparent material; c. Introduce carbon dioxide gas into the reaction container to replace the air; d. Start the microwave, place the reaction container under the microwave field to react, and collect the gaseous products generated by the reaction.

36. The application of the method for simultaneously recovering polyolefins and carbon dioxide using microwaves according to any one of claims 1-35 in the recovery of polyolefins.

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