Method for synergistic pyrolysis treatment of biomass and plastic

Abstract

The invention provides a biomass and plastic synergistic pyrolysis treatment method, which comprises: carrying out first pyrolysis treatment on a biomass raw material to obtain pyrolytic carbon, the pyrolytic carbon comprising an alkali metal element; and mixing the pyrolytic carbon with plastic, and carrying out second pyrolysis treatment to obtain an oil-gas product. According to the scheme, biomass and plastic are pyrolyzed respectively, and the problem that the pyrolysis temperatures of mixed pyrolysis are not overlapped can be avoided. The pyrolytic carbon containing alkali metal after biomass pyrolysis is used as a catalyst to be mixed and pyrolyzed with the plastic, so that the quality of pyrolytic oil of the plastic can be improved, the use of an additional catalyst can be avoided, and the resource utilization rate is increased.

Description

Technical Field

[0001] This invention relates to the field of plastics processing, and more particularly to a method for the synergistic pyrolysis of biomass and plastics. Background Technology

[0002] Waste resource utilization is gradually becoming a key pathway to achieving sustainable development. Biomass (such as agricultural straw and forestry residue) and waste plastics (such as polyethylene, polypropylene, and polyvinyl chloride) are two important types of waste resources, with their annual production increasing year by year. Traditional treatment methods such as landfill and incineration not only lead to resource waste but also cause a series of environmental problems such as soil pollution and greenhouse gas emissions. Pyrolysis technology, as a controllable thermochemical conversion method, can transform waste into fuels, chemicals, and high-value-added materials.

[0003] Currently, co-pyrolysis technology for biomass and waste plastics typically employs physical blending, directly mixing the two types of raw materials before feeding them into a pyrolysis reactor for co-pyrolysis conversion under catalytic or non-catalytic conditions. The target products are mainly bio-oil or fuel gas. However, the pyrolysis temperature of biomass is generally between 250-400℃, while the pyrolysis temperature of waste plastics requires a much higher range, approximately 400-600℃. This non-overlapping temperature windows make it difficult to coordinate the reaction rate and degree of pyrolysis. Under low-temperature conditions, plastics cannot be completely pyrolyzed; while under high-temperature conditions, biomass is prone to over-carbonization, generating low-value-added coke, increasing energy consumption, and reducing the quality of the pyrolysis oil.

[0004] Therefore, improving the quality of pyrolysis oil from waste plastics is an urgent problem to be solved. Summary of the Invention

[0005] This invention provides a method for the synergistic pyrolysis treatment of biomass and plastics, in which pyrolysis carbon from biomass is used as a catalyst and mixed with plastics for pyrolysis to improve the quality of pyrolysis oil from waste plastics.

[0006] In a first aspect, this application provides a method for the synergistic pyrolysis of biomass and plastics, the method comprising:

[0007] The biomass raw material is subjected to a first pyrolysis treatment to obtain pyrolytic carbon, which includes alkali metal elements.

[0008] The pyrolytic carbon is mixed with plastic and then subjected to a second pyrolysis treatment to obtain oil and gas products.

[0009] Furthermore, the mass ratio of the pyrolytic carbon to the plastic is 1:0.5 to 1:2.

[0010] Furthermore, the temperature of the first pyrolysis treatment is 300–400°C.

[0011] Furthermore, the temperature of the second pyrolysis treatment is 400–600°C.

[0012] Furthermore, before mixing the pyrolytic carbon with the plastic, the method further includes:

[0013] The pyrolytic carbon is ground to a particle size of 100-300 mesh.

[0014] Furthermore, the moisture content of the biomass raw material is less than 15%.

[0015] Furthermore, the first pyrolysis treatment takes 20 to 60 minutes, and / or the second pyrolysis treatment takes 20 to 40 minutes.

[0016] Secondly, this application provides a system for the synergistic pyrolysis treatment of biomass and plastics, the system comprising: a first pyrolysis furnace and a second pyrolysis furnace;

[0017] The first pyrolysis furnace is used for pyrolysis of biomass;

[0018] The second pyrolysis furnace is used for pyrolysis of plastics;

[0019] The pyrolytic carbon produced by pyrolyzing biomass in the first pyrolysis furnace is mixed with plastic and then fed into the second pyrolysis furnace.

[0020] Furthermore, the system also includes a burner. After the oil and gas products generated by the first pyrolysis furnace and the pyrolysis gas generated by the second pyrolysis furnace are burned by the burner, the resulting hot flue gas is input into the second pyrolysis furnace for indirect heat exchange.

[0021] Furthermore, the system also includes a grinder, to which the pyrolytic carbon produced by the first pyrolysis furnace from the pyrolysis of biomass is fed for grinding, and then fed to the second pyrolysis furnace.

[0022] This application provides a method for the synergistic pyrolysis of biomass and plastics. The method includes: subjecting biomass feedstock to a first pyrolysis treatment to obtain pyrolytic carbon, which includes alkali metal elements; mixing the pyrolytic carbon with plastics and then subjecting it to a second pyrolysis treatment to obtain oil and gas products. This method pyrolyzes biomass and plastics separately, avoiding the problem of overlapping pyrolysis temperatures in mixed pyrolysis. Using the pyrolytic carbon containing alkali metals from the biomass pyrolysis as a catalyst in the mixed pyrolysis with plastics improves the quality of the pyrolysis oil from the plastics, avoids the use of additional catalysts, and increases resource utilization. Attached Figure Description

[0023] Figure 1 A schematic diagram of the method for synergistic pyrolysis of biomass and plastics provided in this application;

[0024] Figure 2A process flow diagram of the synergistic pyrolysis treatment of biomass and plastics provided for this application;

[0025] Figure 3 Thermogravimetric data for each sample;

[0026] Figure 4 The data are the thermogravimetric rate data for each sample.

[0027] Explanation of reference numerals in the attached figures:

[0028] 1-Crusher; 2-First pyrolysis furnace; 3-Second pyrolysis furnace; 4-Grinding mill; 5-Burner; 6-Heat exchanger. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions in the embodiments of this invention will be clearly and completely described below in conjunction with the embodiments of this invention. Obviously, the described embodiments are only some embodiments of this invention, not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0030] Currently, co-pyrolysis technology for biomass and waste plastics typically employs a physical blending method, directly mixing the two types of raw materials before feeding them into a pyrolysis reactor for co-pyrolysis conversion under catalytic or non-catalytic conditions. The target products are mainly bio-oil or fuel gas. However, this technological approach still faces multiple challenges:

[0031] 1. Thermodynamic mismatch: The pyrolysis temperature range of biomass (such as straw and sawdust) is concentrated between 250-400℃, while that of waste plastics (such as PE and PP) is between 400-600℃. This non-overlapping temperature window makes it difficult to coordinate the reaction rate and the degree of pyrolysis. Under high-temperature conditions, biomass is prone to over-carbonization, increasing energy consumption and generating low-value-added coke; under low-temperature conditions, plastics cannot be completely pyrolyzed.

[0032] 2. Limitations of the catalytic system: In order to improve the quality of pyrolysis oil, it is often necessary to introduce external catalysts (such as alkali metal catalysts and molecular sieve catalysts). However, adding extra catalysts not only significantly increases the process cost, but also faces technical bottlenecks such as catalyst deactivation, recovery and regeneration.

[0033] 3. Product Quality Deterioration: The inherently high oxygen content of biomass results in a high proportion of water, phenols, and carboxylic acids in its pyrolysis oil, leading to poor oil quality. Plastics, primarily composed of carbon and hydrogen, produce relatively high-quality pyrolysis oil. Therefore, the quality of the pyrolysis oil produced by co-pyrolyzing these two raw materials will be dragged down by the inferior biomass pyrolysis oil. Furthermore, the interaction between the pyrolysis products of biomass and plastics during co-pyrolysis creates a more complex mixture, further increasing the difficulty and cost of oil refining.

[0034] In view of this, this application provides a method for the synergistic pyrolysis of biomass and plastics, which eliminates the physical and mechanical mixing of the two raw materials. First, the biomass is pyrolyzed separately to obtain pyrolytic carbon, which includes alkali metal elements. Alkali metal elements can catalyze the pyrolysis of plastics, reduce the content of heavy hydrocarbons, increase the content of aromatic hydrocarbons, improve the quality of oil products from plastic pyrolysis, and reduce the use of additional catalysts.

[0035] The first aspect of this application provides a method for the synergistic pyrolysis treatment of biomass and plastics, such as... Figure 1 As shown, the method includes:

[0036] Step 1: Perform a first pyrolysis treatment on the biomass raw material to obtain pyrolytic carbon, which includes alkali metal elements.

[0037] In this step, biomass raw materials (such as sawdust, straw, etc.) are pyrolyzed to obtain pyrolytic carbon and release some volatile products (oil and gas).

[0038] Biomass feedstocks often contain alkali metal elements (such as sodium, potassium, and calcium). During the first pyrolysis process, these alkali metal elements remain in the pyrolytic carbon, acting as a catalyst for subsequent plastic pyrolysis. Furthermore, the pyrolytic carbon has a high specific surface area and porosity, providing more reaction sites for plastic pyrolysis.

[0039] Step 2: After mixing the pyrolytic carbon with the plastic, a second pyrolysis treatment is carried out to obtain oil and gas products.

[0040] Because the alkali metal elements remaining in the pyrolysis carbon have a catalytic effect, they can promote the pyrolysis process of plastics and lower the activation energy of the reaction. In particular, alkali metal elements (such as potassium and sodium) can promote the cracking of long-chain hydrocarbons in plastics, producing more light oil and gas.

[0041] During pyrolysis, plastics are broken down into hydrocarbon gases and liquid oils. The oil and gas products mainly consist of small-molecule hydrocarbons, aromatic hydrocarbons, and olefins. After pyrolysis, the oil and gas products can be separated into an oil phase and a gas phase using cooling and separation techniques. The gas phase can be further used for combustion to provide heat, while the oil is collected as a product.

[0042] Biomass and waste plastic feedstocks are fed separately. Because the two feedstocks are pyrolyzed separately, the furnace temperature selection is more flexible, allowing for individual selection within the pyrolysis temperature ranges of biomass and plastics, thus avoiding the difficulty in controlling the degree of pyrolysis that occurs with mixed pyrolysis. Simultaneously, the volatiles produced by the pyrolysis of the two feedstocks do not interact, thus avoiding the problem of increasing the complexity of the oil composition. Biochar has a rich porous structure, and the abundant alkali metal elements (potassium, sodium, etc.) in biomass have a good catalytic effect on pyrolysis, which can lower the reaction activation energy, reduce the content of heavy hydrocarbons, increase the content of aromatic hydrocarbons, and improve the quality of the oil. The process fully utilizes the pyrolysis carbon produced in-process as a catalyst, thereby avoiding the introduction of additional external catalysts.

[0043] Since the volatile matter content of plastics can be as high as 100%, there will be no residual carbon after it is fully pyrolyzed. Therefore, the pyrolyzed carbon from biomass can be naturally separated and recycled after being mixed with plastics for reuse.

[0044] Since the pyrolytic carbon has reached a high degree of pyrolysis in the pyrolysis furnace, very little amount of it will volatilize and be released after reheating in the pyrolysis furnace. After the plastic is fully pyrolyzed, it is completely converted into oil and gas products, and the pyrolytic carbon can be naturally separated and recovered from the tail end of the pyrolysis furnace.

[0045] The temperature for the first pyrolysis treatment of biomass feedstock must not be too high. If the temperature is too high, alkali metal elements will react with the organic matter or other minerals in the biomass, forming volatile metal salts or precipitating directly in metallic form. Therefore, the reaction temperature of the first pyrolysis treatment needs to be controlled. Thus, the temperature for the first pyrolysis treatment is 300–400°C. For example, 300°C, 320°C, 340°C, 360°C, 380°C, 400°C, or any range of two of these values.

[0046] Biomass can be pyrolyzed within a temperature range of 300–400℃ without the migration or transformation of alkali metals. For example, the decomposition temperatures of potassium chloride and potassium carbonate are both greater than 700℃.

[0047] To induce pyrolysis of the plastic, the temperature for the second pyrolysis treatment is 400–600°C. For example, 400°C, 450°C, 500°C, 550°C, 600°C, or any range of two of these values.

[0048] In some embodiments, to improve the catalytic effect on the plastic, the mass ratio of pyrolysis carbon to plastic is 1:0.5 to 1:2. For example, 1:0.5, 1:0.75, 1:1, 1:1.5, 1:2, or any combination of two of the above ratios. The pyrolysis oil produced by catalysis within this ratio range has better quality.

[0049] In some embodiments, before adding pyrolytic carbon to plastic for pyrolysis, the pyrolytic carbon is first ground into small particles with a particle size of 100-300 mesh. For example, 100 mesh, 150 mesh, 200 mesh, 250 mesh, 300 mesh, or any combination of two of these values. Within this range, the catalytic effect of plastic pyrolysis can be improved. The ground pyrolytic carbon particles have a larger specific surface area than unground particles. More carbon surface area can react with the plastic, increasing the contact area during pyrolysis and thus enhancing the catalytic effect. The ground pyrolytic carbon particles are also easier to mix uniformly with the plastic, avoiding uneven heating or reaction that may occur with larger particles, thereby improving the overall catalytic efficiency.

[0050] In some embodiments, the biomass feedstock can be dehydrated before the first pyrolysis treatment to reduce its moisture content to less than 15%. Biomass with high moisture content consumes a significant amount of energy to evaporate water during pyrolysis, thus lowering the temperature and efficiency of the pyrolysis reaction. Excessive water vapor may cause some volatile substances in the gas phase to condense back into water, consequently reducing oil and gas production. Dehydration reduces the heat consumed in water evaporation, ensuring a more efficient pyrolysis reaction. Dehydration can be performed through physical extrusion.

[0051] The initial pyrolysis treatment time should be 20–60 minutes, for example, 20, 30, 40, 50, or 60 minutes, or any combination thereof. If the treatment time is too short, the biomass pyrolysis will be incomplete, resulting in poor product quality, insufficient porosity of the pyrolytic carbon, lower levels of oil and gas products, and overall lower efficiency. Pyrolysis exceeding 60 minutes will lead to excessive cracking, increased waste of thermal energy resources, reduction of valuable components in the oil and gas, and a decline in the quality of the pyrolytic carbon. Therefore, a pyrolysis time of 20–60 minutes yields better quality pyrolytic carbon.

[0052] The second pyrolysis treatment time is 20 to 40 minutes, for example, 20 minutes, 25 minutes, 30 minutes, 35 minutes, 40 minutes, or any combination of the above.

[0053] A second aspect of this application provides a system for the synergistic pyrolysis of biomass and plastics, such as... Figure 2 As shown, the system includes: a first pyrolysis furnace 2 and a second pyrolysis furnace 3;

[0054] The first pyrolysis furnace 2 is used for pyrolysis of biomass;

[0055] The second pyrolysis furnace 3 is used for pyrolysis of plastics;

[0056] The pyrolytic carbon produced by pyrolyzing biomass in the first pyrolysis furnace 2 is mixed with plastic and then fed into the second pyrolysis furnace 3.

[0057] In some embodiments, the oil and gas products generated by the second pyrolysis furnace 3 are cooled by the heat exchanger 6 to obtain pyrolysis oil and pyrolysis gas.

[0058] In some embodiments, the system further includes a burner 5. The oil and gas products generated by the first pyrolysis furnace 2 and the pyrolysis gas generated by the second pyrolysis furnace 3 are burned by the burner 5, and the resulting hot flue gas is input into the second pyrolysis furnace 3 for indirect heat exchange. The inlet temperature of the hot flue gas through the second pyrolysis furnace 3 can be controlled at 550-600°C. After heat exchange, the outlet flue gas temperature is still relatively high, so it can be introduced into the first pyrolysis furnace 2 for continued heating. The outlet flue gas of the first pyrolysis furnace is discharged after simple purification.

[0059] In some embodiments, the system further includes a grinder 4. Pyrolytic carbon produced by the pyrolysis of biomass in the first pyrolysis furnace 2 is fed to the grinder 4 for grinding, and then fed to the second pyrolysis furnace 3. The grinder is used to further refine the pyrolytic carbon that has already undergone pyrolysis. This process further grinds larger pyrolytic carbon particles into fine powder. The type of grinder can be a ball mill. During the grinding process, a sieving device can be used to help separate particles that have reached 100-300 mesh from larger particles, ensuring that the ground particles are between 100 and 300 mesh.

[0060] In some embodiments, the system further includes a crusher 1, which is used to break down biomass and plastics. The crusher is mainly used for the preliminary crushing of biomass or plastic raw materials. It breaks the raw materials (biomass or plastics) into smaller particles, facilitating subsequent pyrolysis. Biomass (such as wood, straw, etc.) is initially crushed into smaller particles by the crusher so that it can better contact the heat source during pyrolysis, improving pyrolysis efficiency. For plastics, the crusher tears them into smaller fragments or particles, which increases the surface area of ​​the plastic, promoting more uniform heating during pyrolysis and improving pyrolysis efficiency.

[0061] Optionally, the crushed material can be screened after being broken down by the crusher.

[0062] The following provides a specific process flow for reference. Figure 2 It includes the following steps:

[0063] Step 1: Biomass waste materials with high alkali metal content (potassium content of 0.5-2.0%), such as corn stalks, wheat stalks, corn cobs, and hollow palm fruit bunches, are crushed in crusher 1 to a particle size of less than 10mm. Waste plastics (polypropylene, polyethylene) are also crushed to a particle size of less than 5mm. The moisture content of all raw materials must be less than 15%. If the moisture content is insufficient, some moisture can be removed by compression or other methods.

[0064] Step 2: The crushed biomass raw material is fed into the first pyrolysis furnace 2 by a feeder for pyrolysis. The pyrolysis furnace is preferably a rotary equipment (such as a rotary kiln). The pyrolysis temperature is controlled in the range of 300-400℃, preferably 350℃, and the residence time is controlled in the range of 20-60min, preferably 40min. After pyrolysis, pyrolysis carbon and oil and gas products are obtained. The dry basis yield of pyrolysis carbon can reach 40-55%.

[0065] Step 3: The pyrolysis oil and gas are directly introduced into the burner 5 for combustion, and the pyrolysis carbon is placed in the grinder 4 and ground to a particle size of 100-300 mesh, preferably 200 mesh.

[0066] Step 4: The crushed plastic from Step 1 is mixed with the ground pyrolytic carbon from Step 3 at a mass ratio of 1:0.5-2 and fed into the second pyrolysis furnace 3 for catalytic pyrolysis. The pyrolysis temperature is controlled at 400-600℃, preferably 500℃, and the residence time is controlled at 20-40 minutes. Since the pyrolytic carbon has already reached a high degree of pyrolysis in the first pyrolysis furnace, very little is released after reheating in the second pyrolysis furnace. The plastic, after thorough pyrolysis, is completely converted into oil and gas products, and the pyrolytic carbon can be naturally separated and recovered from the tail end of the pyrolysis furnace. The pyrolysis products of this pyrolysis furnace are mainly pyrolysis oil and pyrolysis gas produced by plastic pyrolysis. The oil and gas products are cooled and separated by heat exchanger 6. The pyrolysis gas enters burner 5 for combustion to supplement heat, and the pyrolysis oil is collected as a product.

[0067] Step 5: The oil and gas products generated by the first pyrolysis furnace and the pyrolysis gas generated by the second pyrolysis furnace are burned by burner 5 and used to heat the system. The hot flue gas is first introduced into the second pyrolysis furnace for heat exchange between the walls after temperature adjustment. The inlet temperature can be controlled at 550-600℃. After heat exchange, the outlet flue gas temperature is still high and can be introduced into the first pyrolysis furnace for continued heating. The outlet flue gas of the first pyrolysis furnace is discharged after simple purification.

[0068] The above-described pyrolysis method yields biomass pyrolysis carbon, a small amount of pyrolysis oil and gas, and plastic pyrolysis oil and gas products. Biomass pyrolysis carbon has a higher energy density and a porous structure compared to biomass feedstock, making it more valuable. However, due to the high oxygen content of biomass, its pyrolysis gas mainly consists of a large amount of CO2 and some CO, resulting in pyrolysis oil with high water content, poor stability, and low quality, leading to low recycling value. Plastic pyrolysis gas contains relatively more small-molecule hydrocarbons such as H2 and CH4, and has a higher calorific value. Therefore, the lower-quality, lower-yield biomass pyrolysis oil and gas products and the relatively higher-calorific-value plastic pyrolysis gas are chosen as the heat source for the pyrolysis system, achieving heat self-sufficiency. The higher-value biomass pyrolysis carbon can be used as a gasification feedstock, and the plastic pyrolysis oil can be used as high-quality fuel oil or for further processing into high-value-added chemicals. Through this approach, efficient pyrolysis of biomass and plastics and the graded resource utilization of pyrolysis products can be achieved.

[0069] In summary, this scheme achieves complete pyrolysis of both raw materials through parallel dual-furnace pyrolysis, thereby improving pyrolysis efficiency. It fully utilizes the catalytic properties of biomass pyrolysis carbon to achieve autocatalysis between products and raw materials, avoiding the introduction of external catalysts and solving the problems of catalyst separation and recovery. Prioritizing the pyrolysis of biomass ensures the release of most of its volatile components, thus avoiding the increased complexity of the pyrolysis oil composition and the difficulty of subsequent refining processes during mixed pyrolysis. It fully utilizes low-quality pyrolysis products to achieve heat self-sufficiency in the biomass-plastic pyrolysis system, while simultaneously producing high-quality pyrolysis carbon and pyrolysis oil.

[0070] The present invention will be further described below through specific embodiments.

[0071] Commercially available corn cobs (whose physicochemical properties are shown in Table 1) were used as raw material to prepare pyrolytic carbon in a tube furnace. Pyrolysis employed a programmed temperature rise method, increasing the furnace temperature from room temperature to 350°C at a heating rate of 5°C / min and maintaining this temperature for 40 min. Nitrogen gas was introduced throughout the experiment to maintain an inert atmosphere. After pyrolysis, the dry basis yield of pyrolytic carbon (YMX) was 41.49%. The pyrolytic carbon was ground and sieved to 200 mesh.

[0072] Table 1. Physicochemical Analysis of Corn Cobs

[0073]

[0074] M ad Indicates water content, A d Indicates dry basis ash content, V d Indicates dry basis volatile content, FC d Indicates dry basis fixed carbon content, C d Indicates dry basis carbon content, H d Indicates dry basis hydrogen content, N d Indicates dry basis nitrogen content, S d Indicates dry basis sulfur content, O d The value indicates the dry basis oxygen content, and K indicates the corn cob ash content.

[0075] Plastic bubble wrap (PLA) was used instead of waste plastic. PLA was crushed and sieved to 20 mesh, and then mixed with the aforementioned pyrolytic carbon at mass ratios of 1:1 (1PLA1YMX), 1:2 (1PLA2YMX), and 2:1 (2PLA1YMX). Six mg of each mixture was taken and subjected to thermogravimetric analysis for thermogravimetric analysis. The test results are as follows: Figure 3 and Figure 4 As shown. In Figure 3 and Figure 4 In this context, the suffix "E" indicates the measured value, and the suffix "C" indicates the theoretical calculated value after mixing. The theoretical calculated value is obtained by combining the thermogravimetric analysis (TGA) data of the two raw materials before mixing, performed individually.

[0076] Depend on Figure 3 Data shows that when biomass pyrolysis carbon is added to waste plastics, the experimental values ​​of the maximum weight loss in the pyrolysis reaction (i.e., the curves with the suffix E) are all higher than the corresponding theoretical calculation values ​​(i.e., the curves with the suffix C), meaning that more material is decomposed at the same temperature. Experimental data indicates that actual decomposition using pyrolysis carbon is easier than decomposition alone, suggesting that pyrolysis carbon has a catalytic effect.

[0077] Depend on Figure 4 The data shows that when biomass pyrolysis carbon is added to waste plastics, the experimental values ​​of the maximum weight loss rate of the pyrolysis reaction (i.e., the curves with the suffix E) are all higher than the corresponding theoretical calculation values ​​(i.e., the curves with the suffix C), meaning that the weight loss rate is faster at the same temperature. This result indicates that the addition of pyrolysis carbon has a positive synergistic effect on the pyrolysis of the mixture, promoting the pyrolysis reaction.

[0078] from Figure 3 and Figure 4 Among the samples, the measured value of 1PLA to 1YMX was greater than the theoretical calculation value, indicating that it was the optimal ratio. Therefore, a mixture of PLA and YMX at a mass ratio of 1:1, as well as a single bubble film (PLA), were selected for thermal decomposition at 500℃, and the pyrolysis oil composition is shown in Table 2.

[0079] Table 2. Pyrolysis oil analysis of bubble film

[0080]

[0081] As shown in Table 2, when pyrolytic carbon is used as a catalyst, the aromatic hydrocarbon content is higher than that of PLA plastic alone. Alkali metals (such as sodium and potassium) in pyrolytic carbon promote olefin cyclization and dehydrogenation, and facilitate the conversion of long-chain olefins into cycloalkanes and aromatic hydrocarbons. Therefore, the catalytic reaction can increase the aromatic hydrocarbon content in pyrolysis oil and improve the quality of the oil.

[0082] The increased aromatic hydrocarbon content in pyrolysis oil leads to a higher overall calorific value. Furthermore, olefins are more prone to oxidation and deterioration than aromatic hydrocarbons, resulting in poorer oil stability. However, catalytic pyrolysis increases the aromatic hydrocarbon content in the pyrolysis oil, thus improving its stability.

[0083] Alkali metal catalysts can lower the activation energy of pyrolysis reactions, allowing the reactions to proceed at lower temperatures, thus accelerating the reaction rate and increasing oil and gas production. Catalysts can also influence the selectivity of the pyrolysis process, promoting the production of specific products in the cracking reaction, such as increasing the formation of olefins and aromatic hydrocarbons.

[0084] In this invention, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance; the term "multiple" refers to two or more unless otherwise expressly defined.

[0085] In the description of this specification, the terms "one embodiment," "some embodiments," "specific embodiment," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0086] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for the synergistic pyrolysis treatment of biomass and plastics, characterized in that, The method includes: The biomass raw material is subjected to a first pyrolysis treatment to obtain pyrolytic carbon, which includes alkali metal elements. The pyrolytic carbon is mixed with plastic and then subjected to a second pyrolysis treatment to obtain oil and gas products.

2. The method according to claim 1, characterized in that, The mass ratio of the pyrolytic carbon to the plastic is 1:0.5 to 1:

2.

3. The method according to claim 1 or 2, characterized in that, The temperature of the first pyrolysis treatment is 300-400℃.

4. The method according to claim 1 or 2, characterized in that, The temperature of the second pyrolysis treatment is 400–600°C.

5. The method according to claim 1 or 2, characterized in that, The method further includes, prior to mixing the pyrolytic carbon with the plastic: The pyrolytic carbon is ground to a particle size of 100-300 mesh.

6. The method according to claim 1 or 2, characterized in that, The moisture content of the biomass feedstock is less than 15%.

7. The method according to claim 1 or 2, characterized in that, The first pyrolysis treatment lasts for 20 to 60 minutes, and / or the second pyrolysis treatment lasts for 20 to 40 minutes.

8. A system for the synergistic pyrolysis treatment of biomass and plastics, characterized in that, The system includes: a first pyrolysis furnace and a second pyrolysis furnace; The first pyrolysis furnace is used for pyrolysis of biomass; The second pyrolysis furnace is used for pyrolysis of plastics; The pyrolytic carbon produced by pyrolyzing biomass in the first pyrolysis furnace is mixed with plastic and then fed into the second pyrolysis furnace.

9. The system according to claim 8, characterized in that, The system also includes a burner. After the oil and gas products generated by the first pyrolysis furnace and the pyrolysis gas generated by the second pyrolysis furnace are burned by the burner, the resulting hot flue gas is input into the second pyrolysis furnace for indirect heat exchange.

10. The system according to claim 8 or 9, characterized in that, The system also includes a grinder, on which the pyrolytic carbon produced by the first pyrolysis furnace from the pyrolysis of biomass is fed to the grinder for grinding, and then fed to the second pyrolysis furnace.

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