Waste plastic pyrolysis-catalysis system based on electromagnetic induction heating and catalytic reforming method

Abstract

The invention discloses a waste plastic pyrolysis-catalysis system based on electromagnetic induction heating and a catalytic reforming method, and relates to the technical field of plastic pyrolysis. The problems that in the existing plastic pyrolysis-catalysis process, the yield and quality of CNTs and H2 are affected by factors such as non-uniform heating, catalyst deactivation and difficult product separation exist are solved. The system comprises a gas inlet device, a waste plastic pyrolysis device, a waste plastic continuous feeding device, a waste plastic catalytic reforming device and a gas collecting device, the gas inlet device is used for providing argon gas flow for the waste plastic pyrolysis device through a gas pipe; the waste plastic continuous feeding device is used for feeding waste plastic into the waste plastic pyrolysis device for heating and cracking; pyrolysis products enter a waste plastic catalytic reforming device after passing through a waste plastic pyrolysis device; according to the waste plastic catalytic reforming device, the temperature is regulated and controlled through the electromagnetic induction heating module, and the catalytic reforming process is optimized; and gas products after catalytic reforming are collected by a gas collecting device. The method is applied to the field of plastic recovery.

Description

Technical Field

[0001] The invention relates to the technical field of plastic pyrolysis, and in particular to a waste plastic pyrolysis-catalysis system based on electromagnetic induction heating. Background Art

[0002] Plastics, especially polyolefins such as polyethylene (PE) and polypropylene (PP), have become the main source of global waste accumulation. Billions of tons of plastic waste are landfilled or pollute the environment every year, causing serious ecological and health threats. In recent years, in order to cope with this problem, plastic recycling technology has received extensive attention and development, which is mainly divided into three categories: physical recycling, chemical recycling and energy recycling.

[0003] Physical recycling methods include washing, shredding and reprocessing. This method is economical and mature in technology, but it requires high purity of plastics, and plastics will gradually degrade after multiple cycles. Chemical recycling degrades waste plastics to produce monomers or low molecular weight compounds, which can be used to synthesize new plastics or chemicals and are suitable for mixed or non-recyclable plastics. In contrast, energy recovery uses incineration of plastics to recover heat energy, but it releases harmful substances such as dioxins, posing a threat to the environment and human health.

[0004] As a new alternative, the pyrolysis-catalytic process of waste plastics is considered a promising method. This process can not only alleviate the environmental and health problems associated with waste plastics, but also generate products with high added value, such as carbon nanotubes CNTs and hydrogen H2. Specifically, the two-step pyrolysis-catalytic process includes the first step of pyrolysis to decompose plastics to generate hydrocarbon volatiles, which are then used as synthetic precursors for CNTs and H2. Compared with traditional fossil fuel alternatives, this process can significantly reduce greenhouse gas emissions while reducing dependence on fossil fuels such as natural gas, and has the potential for sustainable development.

[0005] Although a large number of studies have explored the plastic pyrolysis-catalytic process, there are still many challenges in terms of heat and mass transfer and reactor design, which affect the yield and quality of CNTs and H2. These challenges mainly include uneven heating, catalyst deactivation and product separation, which urgently need further research and optimization. Summary of the invention

[0006] The present invention aims to solve the problem that the production and quality of CNTs and H2 are affected by factors such as uneven heating, catalyst deactivation and difficulty in product separation in the existing plastic pyrolysis-catalysis process, and proposes a waste plastic pyrolysis-catalysis system based on electromagnetic induction heating, the system comprising:

[0007] Air intake device, waste plastic pyrolysis device, waste plastic continuous feeding device, waste plastic catalytic reforming device and gas collection device;

[0008] The air inlet device is used to provide an argon gas flow to the waste plastic pyrolysis device through an air pipe;

[0009] The waste plastic continuous feeding device feeds the waste plastic into the waste plastic pyrolysis device for heating and cracking; the pyrolysis products pass through the waste plastic pyrolysis device and enter the waste plastic catalytic reforming device; the waste plastic catalytic reforming device controls the temperature through an electromagnetic induction heating module to optimize the catalytic reforming process; the gas products after catalytic reforming are collected by a gas collection device.

[0010] Furthermore, a preferred embodiment is proposed, wherein the air intake device comprises an argon gas cylinder and a PU gas pipe, and the PU gas pipe is connected to the argon gas cylinder and is arranged outside the argon gas cylinder.

[0011] Furthermore, a preferred embodiment is proposed, wherein the waste plastic continuous feeding device comprises an extruder and a heating belt, wherein the extruder is used to heat the waste plastic so that the waste plastic melts and flows and is pushed into the waste plastic pyrolysis device through the heating belt; and the temperature of the heating belt is set to 280°C.

[0012] Furthermore, a preferred embodiment is proposed, in which the feeding rate of the waste plastic continuous feeding device is 0 to 0.583 g / min.

[0013] Furthermore, a preferred embodiment is proposed, wherein the waste plastic pyrolysis device comprises a tubular furnace 41, a temperature controller and a quartz glass tube; the tubular furnace and the temperature controller jointly raise the temperature in the quartz glass tube to a target temperature and maintain the target temperature during the pyrolysis experiment; an alumina porous medium is placed at the center of the quartz glass tube; the waste plastic is pyrolyzed through the porous medium, and the pyrolysis products enter the waste plastic catalytic reforming device after passing through a pipeline heated to 200°C by a heating belt.

[0014] Furthermore, a preferred embodiment is proposed, wherein the waste plastic catalytic reforming device comprises a temperature controller, an electromagnetic induction coil, a T-type thermocouple, a quartz glass tube, a metal porous iron and an electromagnetic induction heating module;

[0015] The metal porous iron is arranged in the center position of the quartz glass tube; the electromagnetic induction coil surrounds the outside of the center position of the quartz glass tube; one end of the T-type thermocouple is inserted into the metal porous iron from the lower end of the quartz glass tube to measure the temperature of the metal porous, and the other end is connected to the temperature controller. When there is a difference between the metal porous temperature and the catalytic reforming target temperature, the temperature controller will adjust the alternating current size inside the induction coil, thereby adjusting the metal porous temperature.

[0016] Based on the same inventive concept, the present invention also proposes a method for catalytic reforming of waste plastics based on electromagnetic induction heating. The system is implemented based on any of the above-mentioned waste plastic pyrolysis-catalytic systems based on electromagnetic induction heating. The method comprises:

[0017] Set the initial flow rate and ventilation time of argon gas, and pass argon gas into the quartz glass tube;

[0018] The argon gas flow rate is adjusted to set the target temperature of the tube furnace; when the tube furnace reaches the target temperature, the electromagnetic induction heating module is heated to the target temperature;

[0019] The extruder pushes the molten waste plastic into the tubular furnace at a feed rate of 0.5 g / min;

[0020] The molten waste plastic is initially pyrolyzed into volatiles after passing through porous alumina;

[0021] Argon gas carries the volatiles out of the tube furnace and into the catalytic reformer. The gaseous products produced by the catalytic reformer are collected in a gas bag and analyzed by gas chromatography GC.

[0022] The prepared carbon nanotubes are attached to the metal porous catalyst and separated and collected by mechanical vibration.

[0023] Furthermore, a preferred embodiment is proposed, in which the initial flow rate of the argon gas is set to 300 mL / min, and the ventilation time is set to 20 min.

[0024] Furthermore, a preferred embodiment is proposed, in which the target temperature of the tube furnace is set to 500° C. and the heating rate is 20° C. / min.

[0025] Furthermore, a preferred embodiment is proposed, in which the target temperature of the electromagnetic induction heating module is 900°C.

[0026] The present invention is beneficial in that:

[0027] The present invention proposes a waste plastic pyrolysis-catalysis system based on electromagnetic induction heating, which is used to pyrolyze waste plastic into carbon nanotubes and hydrogen. The novelty of the system lies in the development of an efficient pyrolysis catalytic process for continuously producing carbon nanotubes (CNTs) and hydrogen (H2) from waste plastics using electromagnetic induction heating. Rapid heating is achieved by utilizing porous metal catalysts as catalytic sites and heating carriers, which greatly improves energy efficiency and product yield. This dual-functional approach overcomes the typical heat transfer limitations associated with catalytic reforming of plastic pyrolysis hydrocarbons, thereby ensuring uniform temperature distribution and reducing energy consumption. In addition, the use of Fe porous catalysts can selectively produce high-purity CNTs and H2, thereby maximizing the utilization value of waste plastics. At the same time, the system introduces a continuous feeding system, which is more conducive to achieving scale and industrialization.

[0028] The present invention proposes a waste plastic catalytic reforming method based on electromagnetic induction heating, which adopts electromagnetic induction heating technology to achieve rapid and uniform heating. This heating method does not rely on traditional heat exchange methods (such as resistance heating or combustion heating), and can directly heat the waste plastic in the pipeline, thereby improving the pyrolysis efficiency and shortening the heating time. By accurately controlling the target temperature of the tubular furnace, the process of waste plastic cracking can be optimized, ensuring that the cracking reaction is carried out within the optimal temperature range, and improving the quality and yield of the product.

[0029] The invention is applied to the field of plastic recycling. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 Schematic diagram of a waste plastic pyrolysis-catalysis system based on electromagnetic induction heating according to the first embodiment, wherein 1 represents an air intake device, 2 represents a waste plastic pyrolysis device, 3 represents a waste plastic continuous feeding device, 4 represents a waste plastic catalytic reforming device, 5 represents a gas collection device, 21 represents waste plastic, 22 represents porous alumina, 23 represents a tubular furnace, 31 represents a hot plate belt, 41 represents a temperature controller, 42 represents an electromagnetic induction coil, 43 represents a T-type thermocouple, 44 represents a metal porous iron, and 45 represents an electromagnetic induction heating module;

[0031] Figure 2 This is a data diagram of an example described in Implementation Mode 11, Figure 2 (a) is the carbon yield and gas yield, Figure 2 (b) is the gas selectivity of different gas components, Figure 2 (c) is the result of temperature-programmed oxidation of carbon nanotubes. Figure 2 (d) is the C atom recovery rate and the H atom recovery rate, Figure 2 (e) is the SEM characterization of carbon nanotubes. Figure 2 (f) TEM characterization of carbon nanotubes. DETAILED DESCRIPTION

[0032] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments.

[0033] Embodiment 1: A waste plastic pyrolysis-catalysis system based on electromagnetic induction heating described in this embodiment comprises:

[0034] An air intake device 1, a waste plastic pyrolysis device 2, a waste plastic continuous feeding device 3, a waste plastic catalytic reforming device 4 and a gas collection device 5;

[0035] The air inlet device 1 is used to provide an argon gas flow to the waste plastic 21 pyrolysis device 2 through an air pipe;

[0036] The waste plastic continuous feeding device 3 feeds the waste plastic into the waste plastic pyrolysis device 2 for heating and cracking; the pyrolysis products pass through the waste plastic pyrolysis device 2 and enter the waste plastic catalytic reforming device 4; the waste plastic catalytic reforming device 4 controls the temperature through an electromagnetic induction heating module to optimize the catalytic reforming process; the gas products after catalytic reforming are collected by the gas collection device 5.

[0037] The traditional pyrolysis process of waste plastics usually relies on external heating sources (such as electric furnaces or gas heating). These heating methods are prone to uneven heating problems, resulting in low cracking efficiency and unstable product quality.

[0038] In the system proposed in this embodiment, electromagnetic induction heating technology is used to directly act on the catalyst and the waste plastic itself through a high-frequency electromagnetic field, so that it can achieve more uniform and rapid heating during the heating process. Electromagnetic induction heating has a high energy conversion efficiency, can increase the temperature of the entire system in a short time, and ensure that the temperature in the pyrolysis area is uniform, thereby improving the efficiency of the cracking reaction and the quality of the product.

[0039] The gas and liquid products produced during the pyrolysis of waste plastics need to be separated and collected in a timely manner. Traditional separation methods often require more complex equipment and longer operation time, and are prone to product loss.

[0040] In this embodiment, the electromagnetic induction heating module in the waste plastic catalytic reforming device controls the temperature, which can optimize the conditions of the pyrolysis reaction, making the gasification and cracking of the reaction products more complete, thereby improving the yield and purity of the gas products. The products after catalytic reforming are efficiently collected by the gas collection device, which reduces the difficulty of separation and improves the overall yield of the system.

[0041] Embodiment 2: This embodiment further limits the waste plastic pyrolysis-catalysis system based on electromagnetic induction heating described in Embodiment 1. The air intake device 1 includes an argon gas cylinder and a PU gas pipe. The PU gas pipe is connected to the argon gas cylinder and is arranged outside the argon gas cylinder.

[0042] As an inert gas, argon is not easy to react chemically with waste plastics, which is crucial for the pyrolysis process of waste plastics. Traditional pyrolysis processes often face the problem of oxygen participating in the oxidation reaction, which not only reduces the quality of the product, but also may produce harmful byproducts such as toxic gases and black smoke. Argon can effectively isolate oxygen, ensuring that only cracking reactions occur during the pyrolysis of waste plastics, ensuring the stability and purity of the product quality.

[0043] The argon cylinder is connected to the waste plastic pyrolysis device through a PU air pipe, which can better control the flow rate and direction of the gas. By adjusting the pressure of the argon cylinder, the air intake device can accurately control the argon flow entering the waste plastic pyrolysis device to ensure stable airflow and avoid uneven or unstable pyrolysis effects caused by airflow fluctuations. Reasonable design of the air intake device and airflow control help optimize the entire cracking process and improve energy efficiency and product quality.

[0044] Embodiment 3. This embodiment is a further limitation of the waste plastic pyrolysis-catalytic system based on electromagnetic induction heating described in embodiment 1. The waste plastic continuous feeding device 3 includes an extruder and a heating belt. The extruder is used to heat the waste plastic so that the waste plastic melts and flows and is pushed into the waste plastic pyrolysis device 2 through the heating belt. The temperature of the heating belt is set to 280°C.

[0045] The role of the extruder in this embodiment is to heat the waste plastic to a molten state through mechanical pressure and heating. The extrusion process can not only heat the waste plastic efficiently, but also convert the waste plastic from a solid state to a fluid state, ensuring that it can participate in the reaction more evenly in the subsequent pyrolysis process. The role of the heating belt is to heat the waste plastic at a constant temperature during transportation to prevent the waste plastic from solidifying or agglomerating due to temperature reduction. The continuous heating of the heating belt can ensure that the waste plastic is always kept in a suitable temperature range during transportation, avoid uneven heating, improve the overall heating efficiency of the system, and prevent the molten waste plastic from cooling and solidifying and clogging the pipeline.

[0046] The system described in this embodiment adopts a continuous feeding device, which makes the feeding process of waste plastics smoother and avoids the temperature fluctuation and downtime that may occur in traditional batch feeding. Through continuous extrusion and heating, the system can achieve continuous feeding and pyrolysis of waste plastics, greatly improving production efficiency, reducing downtime, and maintaining the stability of the pyrolysis process.

[0047] Embodiment 4: This embodiment further limits the waste plastic pyrolysis-catalysis system based on electromagnetic induction heating described in Embodiment 1, and the feeding rate of the waste plastic continuous feeding device 3 is 0 to 0.583 g / min.

[0048] Embodiment 5. This embodiment further limits the waste plastic pyrolysis-catalytic system based on electromagnetic induction heating described in embodiment 1. The waste plastic pyrolysis device 2 comprises a tubular furnace 41, a temperature controller and a quartz glass tube; the tubular furnace 41 and the temperature controller jointly raise the temperature in the quartz glass tube to the target temperature and maintain it at the target temperature during the pyrolysis experiment; an alumina porous medium is placed at the center of the quartz glass tube; the waste plastic is pyrolyzed by the porous medium, and the pyrolysis product enters the waste plastic catalytic reforming device 4 after passing through a pipeline heated to 200°C by a heating belt.

[0049] In this embodiment, the temperature controller and the tube furnace work together to accurately control the temperature inside the quartz glass tube to ensure that the cracking reaction is carried out stably at the preset target temperature. This precise temperature control can avoid the adverse effects of temperature fluctuations on the cracking process and improve the efficiency of waste plastic cracking and the quality of the product. During the pyrolysis process, the temperature controller can continuously monitor and adjust the temperature to ensure that the system can maintain the target temperature during the pyrolysis experiment, which is conducive to the efficient pyrolysis of waste plastics.

[0050] The alumina porous medium is placed in the center of the quartz glass tube, which can promote the pyrolysis reaction of waste plastics. Alumina has good thermal stability and catalytic effect, which can effectively increase the surface area of ​​the pyrolysis reaction, and the porous structure can effectively increase the reaction rate. Through such a design, the efficiency of the pyrolysis process can be improved and energy consumption can be reduced. Pyrolysis of waste plastics through porous media can ensure uniform heating, avoid local overheating or overcooling, and reduce incomplete pyrolysis.

[0051] The pyrolysis products enter the waste plastic catalytic reforming unit after passing through the pipeline heated to 200°C by the heating belt. This process helps to avoid condensation of the pyrolysis products and blockage of the pipeline. The temperature heated to 200°C is suitable for guiding the products into the subsequent catalytic reforming unit to further promote the conversion of the products. The waste plastic catalytic reforming unit further processes the cracking products after pyrolysis, which can improve the conversion rate of waste plastics.

[0052] Embodiment 6. This embodiment is a further limitation of the waste plastic pyrolysis-catalytic system based on electromagnetic induction heating described in embodiment 1. The waste plastic catalytic reforming device 4 includes a temperature controller 41, an electromagnetic induction coil 42, a T-type thermocouple 43, a quartz glass tube, a metal porous iron 44 and an electromagnetic induction heating module 45.

[0053] The metal porous iron 44 is arranged in the center of the quartz glass tube; the electromagnetic induction coil 42 surrounds the outside of the center of the quartz glass tube; one end of the T-type thermocouple 43 is inserted into the metal porous iron from the lower end of the quartz glass tube to measure the temperature of the metal porous, and the other end is connected to the temperature controller. When there is a difference between the metal porous temperature and the catalytic reforming target temperature, the temperature controller will adjust the alternating current inside the induction coil, thereby adjusting the metal porous temperature.

[0054] In this embodiment, the electromagnetic induction coil 42 provides a fast and efficient heating method. Compared with traditional heat source heating (such as electric heating pipes, combustion, etc.), this heating method can make the metal porous iron 44 reach the required catalytic reforming temperature in a shorter time, thereby improving the working efficiency of the system. Since electromagnetic induction heating directly acts on the metal porous iron through electric current, it can ensure uniform heating, and there will be no problem of reduced catalytic efficiency or equipment damage caused by uneven temperature.

[0055] Furthermore, the cooperation between the T-type thermocouple 43 and the temperature controller 41 can monitor the temperature of the metal porous iron in real time. When the temperature differs from the set catalytic reforming target temperature, the temperature controller will adjust the alternating current in the electromagnetic induction coil to accurately adjust the heating temperature and ensure the accuracy and stability of the process temperature control.

[0056] In practical applications, when the metal porous iron needs to be heated to the target temperature, an alternating current will be generated inside the electromagnetic induction coil. When the alternating current passes through the induction coil, an alternating magnetic field will be generated in the surrounding space according to the law of electromagnetic induction. Since the metal porous iron has excellent electrical conductivity, the alternating magnetic field will generate an induced current inside it. This induced current is called eddy current. When the eddy current flows through the metal material, Joule heat will be generated due to the presence of resistance, that is, the material is heated by the current. Using a metal porous catalyst as a heating carrier can achieve rapid volume heating. At the same time, the metal porous iron 44 also acts as a catalyst and can provide catalytic action during the cracking of waste plastics. Due to the special structure of the metal porous iron, it can not only provide a large reaction surface area, but also its porous structure helps the contact between the reactant and the catalyst, thereby improving the catalytic efficiency. By using the metal porous iron as a catalyst, it can be recycled multiple times during the cracking reaction, reducing the consumption of the catalyst and reducing the production cost. The metal porous iron has good thermal conductivity, can quickly absorb the heat provided by the electromagnetic induction heating, and effectively transfer the heat to the reactant, prompting the plastic to decompose and convert into carbon nanotubes.

[0057] Furthermore, the separation of metallic porous iron and the product carbon nanotubes can be achieved through simple shaking, avoiding the traditional cumbersome separation steps and reducing the loss and energy consumption in the separation process. This separation method can effectively prevent the catalyst from remaining in the final product and improve the purity of products such as carbon nanotubes.

[0058] Embodiment 7: A method for catalytic reforming of waste plastics based on electromagnetic induction heating described in this embodiment, the system is implemented based on a waste plastic pyrolysis-catalytic system based on electromagnetic induction heating described in any one of embodiments 1 to 6, and the method includes:

[0059] Set the initial flow rate and ventilation time of argon gas, and pass argon gas into the quartz glass tube;

[0060] Adjust the argon gas flow rate and set the target temperature of the tube furnace; when the tube furnace reaches the target temperature, turn on the electromagnetic induction heating module and heat the electromagnetic induction heating module to the target temperature;

[0061] The extruder pushes the molten waste plastic into the tubular furnace at a feed rate of 0.5 g / min;

[0062] The molten waste plastic is initially pyrolyzed into volatiles after passing through porous alumina;

[0063] Argon gas carries the volatiles out of the tube furnace and into the catalytic reformer. The gaseous products produced by the catalytic reformer are collected in a gas bag and analyzed by gas chromatography GC.

[0064] The prepared carbon nanotubes are attached to the metal porous catalyst and separated and collected by mechanical vibration.

[0065] The method proposed in this embodiment adopts electromagnetic induction heating technology to achieve rapid and uniform heating. This heating method does not rely on traditional heat exchange methods (such as resistance heating or combustion heating), and can directly heat the target material (such as waste plastics) in the pipeline, thereby improving the pyrolysis efficiency and shortening the heating time. By accurately controlling the target temperature of the tubular furnace, the process of waste plastic cracking can be optimized, ensuring that the cracking reaction is carried out within the optimal temperature range, and improving the quality and yield of the product.

[0066] As an inert gas, argon can effectively prevent oxidation reactions of waste plastics during high-temperature cracking and reduce the generation of harmful gases (such as carbon dioxide, carbon monoxide, etc.). This not only improves the purity of the cracking process, but also helps to control the emission of toxic gases. The argon flow rate and ventilation time can be adjusted according to experimental requirements to further optimize the environmental conditions of waste plastic pyrolysis-catalysis, avoid interference from other gases (such as air), and thus improve the quality of waste plastic pyrolysis-catalysis and the purity of gas products. The waste plastic cracking products enter the catalytic reforming device through the carrier gas. Catalytic reforming can effectively convert volatile gases, change their molecular structure, and generate more valuable chemicals (such as olefins, aromatic hydrocarbons, etc.). The use of this device can significantly improve the quality of gas products and provide high-quality raw materials for further chemical synthesis. The collected gas products can be analyzed by gas chromatography (GC), which can accurately monitor the composition of the gas, further optimize the cracking process and catalytic reforming process, and ensure the consistency and high quality of the products.

[0067] In the pyrolysis-catalytic process of waste plastics, carbon nanotubes can be attached to the metal porous catalyst through the action of the catalyst. This method can not only effectively extract carbon resources from waste plastics, but also separate and collect carbon nanotubes through subsequent mechanical vibration.

[0068] Embodiment 8: This embodiment further limits the method for catalytic reforming of waste plastics based on electromagnetic induction heating described in Embodiment 7. The initial flow rate of argon gas is set to 300 mL / min, and the ventilation time is set to 20 min.

[0069] In the present embodiment, the initial flow rate of argon is set to 300mL / min, which helps to maintain the atmosphere stability during the cracking reaction. The ventilation time is set to 20 minutes, which can ensure that the argon can fully contact the waste plastics in the cracking reaction area in the initial stage of the cracking reaction. This time period helps to complete the pretreatment of the atmosphere and ensure the smooth progress of the cracking process. The longer ventilation time can also help to remove the impurity gas in the system and avoid gas residues that may have a negative impact on the quality of the cracked product.

[0070] Embodiment 9: This embodiment further limits the method for catalytic reforming of waste plastics based on electromagnetic induction heating described in embodiment 7. The target temperature of the tubular furnace is set to 500° C., and the heating rate is 20° C. / min.

[0071] In this embodiment, by setting a target temperature of 500°C and a heating rate of 20°C / min, excessive cracking caused by too high a temperature or too fast a heating rate can be better avoided. For example, if the temperature is too high, it may cause excessive light hydrocarbon components in the cracking product, and may even cause the generation of certain harmful substances. Reasonable heating rate and temperature settings can ensure that the waste plastics are properly decomposed during the cracking process and minimize the generation of undesirable by-products.

[0072] Embodiment 10: This embodiment further limits the method for catalytic reforming of waste plastics based on electromagnetic induction heating described in embodiment 7, and the target temperature of the electromagnetic induction heating module is 900°C.

[0073] In this embodiment, the target temperature is set at 900°C, which can be heated to the required temperature in a relatively short time. At the same time, the temperature control is precise, avoiding temperature fluctuations and overheating in traditional heating methods, and ensuring the stability of the waste plastic cracking process.

[0074] Implementation Method 11: See Figure 2 This embodiment provides a specific example of the waste plastic pyrolysis-catalysis system based on electromagnetic induction heating described in the first embodiment, and is also used to explain the second to sixth embodiments. Specifically:

[0075] 1. Preliminary preparation

[0076] The waste plastics used in this system, low-density polyethylene (LDPE), high-density polyethylene (HDPE), polypropylene (PP), recycled polyethylene (WPE), and recycled polypropylene (WPP), are about 3 mm in diameter and dried in a vacuum oven at 100 ° C for 24 hours to remove moisture from the plastic particles, and then subjected to pyrolysis-catalytic reforming experiments. The porous alumina and porous iron catalysts used in this system are cylindrical, 43 mm in diameter and 10 mm in height. The porosity is 0.97, and the metal porous catalysts are divided into 10, 20, and 30 pores per inch (PPI).

[0077] (II) System Implementation Process

[0078] First, argon gas was introduced into the quartz glass tube of the tubular furnace at a flow rate of 300 mL / min for 20 minutes. Since the quartz glass tube of the tubular furnace was connected to the quartz glass tube in the waste plastic catalytic reforming device, the entire experimental process could be ensured to be in an inert atmosphere. Subsequently, the argon flow rate was adjusted to 25 mL / min, the target temperature of the tubular furnace was set at 500 °C, and the heating rate was 20 °C / min. Since the electromagnetic induction heating speed far exceeded the heating speed of the tubular furnace, the electromagnetic induction device was heated to the target temperature (900 °C) when the tubular furnace was about to reach the target temperature. Then, the extruder continuously pushed the molten waste plastic into the tubular furnace at a feed rate of 0.5 g / min. The molten waste plastic was initially pyrolyzed into volatiles after passing through the porous alumina. The volatiles were carried out of the tubular furnace by the carrier gas and entered the catalytic reforming device. The gas products produced by the catalytic reforming device were collected in the air bag and further analyzed by gas chromatography (GC). The prepared carbon nanotubes were attached to the metal porous catalyst and separated and collected by mechanical vibration.

[0079] (III) Data processing

[0080] The experimental gas products are mainly composed of H2, CH4, C2H4, C2H6, and CO. The flame ionization detector (FID) in the gas chromatograph (SCION 8500-GC) is used to measure the gas components H2 and CO, and the thermal conductivity detector (TCD) is used to measure the gas components CH4, C2H4, and C2H6, so as to obtain the volume fraction V of all gas products. i Since no liquid oil and waxy components are produced when the catalytic reforming temperature is greater than 700°C, the total mass of the gaseous product can be calculated according to the principle of conservation of mass.

[0081] m g =mm s -m a (1)

[0082] Where m g is the mass of gas product, m is the mass of reactant, m s is the mass of solid product, ma is the mass of ash product.

[0083] Yield Y of each gas product component i (mmol / g plastic) is calculated as:

[0084]

[0085] Where V i is the volume fraction of gas component i (H2, CH4, C2H4, C2H6, CO) measured by gas chromatography, M i is the molar mass of gas component i.

[0086] Selectivity of each gas product component C i (mmol / g plastic) is calculated as:

[0087]

[0088] H atom recovery efficiency E H The calculation formula is:

[0089]

[0090] C atom recovery efficiency E C The calculation formula is:

[0091]

[0092] The mass difference of the porous medium before and after the reaction is the mass of the solid product (carbon), and the purity of the carbon nanotubes in the solid product carbon is identified by programmed temperature oxidation (TPO). Carbon nanotubes have a highly ordered graphitized structure. During the TPO process, the oxidation temperature of carbon nanotubes is usually high, so the mass loss of solid carbon below 55 0°C is mainly the oxidation of amorphous carbon. Therefore, the yield of carbon nanotubes can be calculated by multiplying the total mass of carbon in the sample by the proportion of carbon nanotubes in the TPO analysis.

[0093] (IV) Key indicators

[0094] like Figure 2As shown, in this embodiment, the carbon yield and gas yield of the system, the gas selectivity of different component gases, the results of programmed temperature oxidation of carbon nanotubes, the C atom recovery rate and the H atom recovery rate, the SEM characterization of carbon nanotubes, and the TEM characterization of carbon nanotubes were evaluated respectively. The results show that the waste plastic pyrolysis-catalysis system based on electromagnetic induction heating constructed by the present invention has the highest carbon nanotube yield among all current systems. The combination of electromagnetic induction heating and metal porous catalysts (especially iron) provides a promising approach for sustainable waste plastic management. The high efficiency, stability and scalability of the system make it a viable option for large-scale applications, helping to reduce waste and produce valuable materials such as carbon nanotubes and H2.

[0095] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present disclosure rather than to limit its protection scope. Although the present disclosure has been described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that after reading the present disclosure, those skilled in the art can still make various changes, modifications or equivalent substitutions to the specific implementation methods of the invention, but these changes, modifications or equivalent substitutions are all within the protection scope of the disclosed claims to be approved.

Claims

1. A waste plastic pyrolysis-catalysis system based on electromagnetic induction heating, characterized in that: The system comprises: An air intake device (1), a waste plastic pyrolysis device (2), a waste plastic continuous feeding device (3), a waste plastic catalytic reforming device (4) and a gas collection device (5); The air inlet device (1) is used to provide an argon gas flow to the waste plastic (21) pyrolysis device (2) through an air pipe; The waste plastic continuous feeding device (3) feeds the waste plastic into the waste plastic pyrolysis device (2) for heating and cracking; the pyrolysis products pass through the waste plastic pyrolysis device (2) and enter the waste plastic catalytic reforming device (4); the waste plastic catalytic reforming device (4) controls the temperature through an electromagnetic induction heating module to optimize the catalytic reforming process; the gas product after catalytic reforming is collected through a gas collection device (5).

2. A waste plastic pyrolysis-catalysis system based on electromagnetic induction heating according to claim 1, characterized in that: The air intake device (1) comprises an argon gas cylinder and a PU gas pipe, wherein the PU gas pipe is connected to the argon gas cylinder and is arranged outside the argon gas cylinder.

3. The waste plastic pyrolysis-catalysis system based on electromagnetic induction heating according to claim 1 is characterized in that: The waste plastic continuous feeding device (3) comprises an extruder and a heating belt, wherein the extruder is used to heat the waste plastic so that the waste plastic melts and flows and is pushed into the waste plastic pyrolysis device (2) through the heating belt; the temperature of the heating belt is set to 280°C.

4. The waste plastic pyrolysis-catalysis system based on electromagnetic induction heating according to claim 1, characterized in that: The feeding rate of the waste plastic continuous feeding device (3) is 0 to 0.583 g / min.

5. The waste plastic pyrolysis-catalysis system based on electromagnetic induction heating according to claim 1, characterized in that: The waste plastic pyrolysis device (2) comprises a tubular furnace (41), a temperature controller and a quartz glass tube; the tubular furnace (41) and the temperature controller together raise the temperature in the quartz glass tube to a target temperature and maintain the target temperature during the pyrolysis experiment; an alumina porous medium is placed at the center of the quartz glass tube; the waste plastic is pyrolyzed by the porous medium, and the pyrolysis product passes through a pipeline heated to 200° C. by a heating belt and then enters the waste plastic catalytic reforming device (4).

6. The waste plastic pyrolysis-catalysis system based on electromagnetic induction heating according to claim 1, characterized in that: The waste plastic catalytic reforming device (4) comprises a temperature controller (41), an electromagnetic induction coil (42), a T-type thermocouple (43), a quartz glass tube, a metal porous iron (44) and an electromagnetic induction heating module (45); The metal porous iron (44) is arranged in the center of the quartz glass tube; the electromagnetic induction coil (42) surrounds the outside of the center of the quartz glass tube; one end of the T-type thermocouple (43) is inserted into the metal porous iron from the lower end of the quartz glass tube to measure the temperature of the metal porous, and the other end is connected to a temperature controller. When there is a difference between the temperature of the metal porous and the target temperature of catalytic reforming, the temperature controller will adjust the size of the alternating current inside the induction coil, thereby adjusting the temperature of the metal porous.

7. A method for catalytic reforming of waste plastics based on electromagnetic induction heating, characterized in that: The system is implemented based on a waste plastic pyrolysis-catalysis system based on electromagnetic induction heating as described in any one of claims 1 to 6, and the method comprises: Set the initial flow rate and ventilation time of argon gas, and pass argon gas into the quartz glass tube; Adjust the argon gas flow rate and set the target temperature of the tube furnace; when the tube furnace reaches the target temperature, turn on the electromagnetic induction heating module and heat the electromagnetic induction heating module to the target temperature; The extruder pushes the molten waste plastic into the tubular furnace at a feed rate of 0.5 g / min; The molten waste plastic is initially pyrolyzed into volatiles after passing through porous alumina; Argon gas carries the volatiles out of the tube furnace and into the catalytic reformer. The gaseous products produced by the catalytic reformer are collected in a gas bag and analyzed by gas chromatography GC. The prepared carbon nanotubes are attached to the metal porous catalyst and separated and collected by mechanical vibration.

8. A method for catalytic reforming of waste plastics based on electromagnetic induction heating according to claim 7, characterized in that: The initial flow rate of the argon gas was set to 300 mL / min, and the ventilation time was set to 20 min.

9. The method for catalytic reforming of waste plastics based on electromagnetic induction heating according to claim 7, characterized in that: The target temperature of the tube furnace was set to 500°C, and the heating rate was 20°C / min.

10. The method for catalytic reforming of waste plastics based on electromagnetic induction heating according to claim 7, characterized in that: The target temperature of the electromagnetic induction heating module is 900°C.

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