Preparation method of pillared clay catalyst and biomass waste plastic co-cracking application

Abstract

The invention discloses a preparation method of an aluminum pillared catalyst and application of the aluminum pillared catalyst in preparation of aviation kerosene. The catalyst is prepared by adopting an ion exchange intercalation method, namely an aluminum pillared precursor is introduced between clay layers, and the catalyst is obtained by washing, drying and roasting. According to the method, a dual adjustment mechanism based on interlayer swelling degree and pillared density is constructed by adjusting pillared parameters and a clay matrix, so that exposure of endogenous acid of a clay laminate and introduction of exogenous acid of an interlayer aluminum oxide column are accurately controlled; accurate regulation and control on the acid distribution on the surface of the catalyst are realized (namely, the adjustable range of the weak / medium acid / strong acid ratio is 0.32-20.71). Moreover, the aluminum pillared catalyst is applied to co-cracking of biomass and waste plastics, and the synergistic conversion effect among the raw materials is enhanced by utilizing the characteristics of adjustable acid distribution and high specific surface area of the aluminum pillared catalyst, so that the yield and quality of the aviation kerosene component which is obviously superior to those of the aviation kerosene component which is independently cracked are obtained.

Description

Technical Field

[0001] This invention relates to a method for catalytic pyrolysis of biomass and / or waste plastics, and more specifically, to an aluminum pillared catalyst prepared by a specific method and its application in the co-pyrolysis of biomass and waste plastics. Background Technology

[0002] Biomass and waste plastics are two types of solid waste generated in enormous quantities globally, originating widely from agricultural production, household packaging, and industrial processes. Currently, they are mainly disposed of through landfill or direct incineration, resulting not only in a huge waste of resources but also in serious greenhouse gas emissions and environmental pollution. Utilizing biomass or waste plastics to produce fuel, turning waste into treasure, is a low-cost, large-scale green new path.

[0003] Chinese patent application publication CN109158100A discloses a catalyst for the catalytic cracking of waste plastics to produce fuel oil. This catalyst comprises modified pillared clay and a supported metal catalyst. The modified pillared clay is prepared from montmorillonite or kaolinite groups. The montmorillonite group includes bentonite, soapstone, and montmorillonite, while the kaolinite group includes kaolinite and / or halloysite. The modified pillared clay has a particle size of less than 20 μm, an average pore size of more than 50 nm, and a BET surface area of ​​100-400 m². 2 / g; the modified pillared clay has a silica to alumina molar ratio of 4-50:1, the alumina accounts for 2-26% of the total catalyst weight, the silica accounts for 45-87 wt% of the total catalyst weight, and the metal catalyst accounts for 10-35% of the total catalyst weight. The metal catalyst includes transition metal compounds that exhibit catalytic activity and non-transition metal compounds that do not exhibit catalytic activity. Transition metals include metals from Groups IIB, IVB, and VIII, and the transition metal compounds exist in the form of hydrochlorides, silver nitrates, and sulfates. This catalyst can be used for the catalytic pyrolysis of mixed plastic raw materials and hydrocarbon materials.

[0004] Existing catalysts for the pyrolysis of waste plastics or biomass mostly rely on transition metals or noble metals as active components. This not only results in high raw material costs but also cumbersome preparation processes, hindering large-scale industrial application. Furthermore, the complex pyrolysis reaction leads to a wide product distribution and low yield of liquid hydrocarbon fuels. Therefore, there is an urgent need to develop a catalyst that uses inexpensive and readily available raw materials, has a simple preparation method, and possesses excellent catalytic pyrolysis performance for the targeted preparation of liquid hydrocarbon fuels. This would reduce production costs, improve economic efficiency, and increase catalytic pyrolysis efficiency. Summary of the Invention

[0005] One objective of this invention is to improve the selectivity of biomass and waste plastics co-pyrolysis to produce aviation kerosene by precisely controlling the acid distribution of the aluminum-pillared catalyst. Simultaneously, the unique interlayer hierarchical porous structure and high specific surface area of ​​the aluminum-pillared catalyst enhance the diffusion and synergistic conversion of reactant molecules, significantly improving the yield and quality of aviation kerosene fractions from the catalytic pyrolysis of biomass and waste plastics. This also improves the utilization rate of biomass.

[0006] The aluminum pillaring agent (or active component) of this invention exhibits excellent dispersion uniformity and order within the layered clay layers, effectively constructing unobstructed two-dimensional mesoporous channels, thereby improving the specific surface area of ​​the catalyst and the utilization rate of active sites. During the process of introducing the aluminum pillaring agent into the clay interlayer to regulate acid distribution and pore structure, the collapse or destruction of the layered framework is avoided, ensuring that the resulting aluminum pillared catalyst possesses excellent high-temperature resistance. Its application in co-cracking reactions guarantees the thermal stability and service life of the catalyst.

[0007] The present invention provides a method for co-pyrolysis of biomass and waste plastics, comprising: catalytic pyrolysis of biomass and waste plastics under the action of aluminum clay catalyst, with a reaction temperature of 450-600 ℃; The preparation method of the aluminum pillar catalyst includes: (1) adding alkaline solution dropwise into an aluminum salt solution and aging it at room temperature to obtain an aluminum pillar solution; (2) The polyhydroxy aluminum cations in the aluminum pillar liquid undergo ion exchange with the interlayer cations of clay to obtain an aluminum pillar clay catalyst precursor. The mass ratio of the aluminum source to the clay is 2.5-10 mmol / g. (3) The aluminum pillared clay catalyst precursor in step (2) is washed until it is neutral or close to neutral. The washed solid material is dried and calcined to obtain the aluminum pillared clay catalyst.

[0008] This invention achieves precise and directional control of the acidity distribution on the surface of aluminum pillared catalysts. It eliminates the reliance on layer-expanding agents and organic solvents in traditional processes, employing a direct intercalation method using pillared liquids. This is achieved through fine-tuning of key parameters in the synthesis process (such as Al). 3+ Concentration, Al 3+ A catalytic system with highly tunable acidity characteristics was successfully constructed by adjusting the mass ratio of Al to clay and the type of clay matrix. Specifically, Al... 3+ Concentration primarily controls the degree of clay swelling and the openness of interlayer domains by regulating the activity and osmotic pressure of interlayer water molecules, thereby determining the degree of exposure of intrinsic acidic sites in the clay strata; Al 3+The mass ratio of the substance to the clay directly determines the load density (i.e., the amount of pillars) of the interlayer pillar precursor. With the optimization of the amount of pillars, the more aluminum pillars introduced, the richer the exogenous acidic sites provided by the alumina pillars. The clay matrix type, with its unique crystal structure and cation exchange capacity, determines the inherent acid strength basis of the layer and its ability to exchange ions with the pillar liquid.

[0009] This invention applies an aluminum-pillared catalyst to a co-pyrolysis system of biomass and waste plastics. The catalyst's large specific surface area increases the exposure of active sites, significantly enhancing its contact and mass transfer efficiency with macromolecular polymers. Based on this, the co-pyrolysis system exhibits a significant synergistic enhancement effect: on the one hand, the oxygen-containing free radicals released during the thermal decomposition of biomass act as initiators, inducing waste plastics to lower their activation energy and undergo directional chain scission, effectively suppressing excessive pyrolysis caused by high temperatures; on the other hand, the hydrogen-rich intermediates formed from the pyrolysis of waste plastics act as hydrogen donors, promoting the removal of oxygen-containing groups from biomass in the form of H2O, CO, or CO2 through hydrogen transfer reactions, thereby significantly reducing the oxygen content of the products. Overall, the performance is significantly better than that of pyrolysis alone. More importantly, the highly tunable acid distribution of this catalyst can precisely control the degree of C / C bond cleavage, CO bond breaking, and hydrogen transfer reactions. Through directional intervention in the reaction network, the carbon chain length of the products is ultimately precisely locked within the range of aviation kerosene components. Attached Figure Description

[0010] Figure 1 The nitrogen adsorption-desorption isotherms are for the aluminum pillared clay catalysts prepared in Examples 1 to 5 and Comparative Examples 1 to 2. Figure 2 NH3-TPD curves of the aluminum pillared clay catalysts prepared in Examples 1 to 5 and Comparative Examples 1 to 2; Figure 3 The graph shows the gas-liquid-solid yield of the biomass and waste plastic co-pyrolysis of the aluminum pillared clay catalysts prepared in Examples 1 to 5 and Comparative Examples 1 to 2. Figure 4 The carbon number distribution diagrams of the biomass and waste plastic co-pyrolysis liquid phase of the aluminum pillared clay catalysts prepared in Examples 1 to 5 and Comparative Examples 1 to 2 are shown.

[0011] Figure 5 The correlation between the biomass and waste plastic co-pyrolysis jet fuel component yield and the ratio of weak to medium acid to strong acid of the aluminum pillared clay catalysts prepared in Examples 1 to 5 and Comparative Examples 1 to 2 is shown in Figure (a), and the correlation between the jet fuel component yield and strong acid per unit specific surface area is shown in Figure (b).

[0012] Figure 6 The graphs show the gas-liquid-solid recovery rates of biomass and waste plastics in separate and co-pyrolysis in Examples 1, 6 to 7 and Comparative Examples 3 to 4. Figure 7The carbon number distribution diagrams of the liquid phase of biomass and waste plastics in separate pyrolysis and co-pyrolysis are shown for Examples 1, 6 to 7 and Comparative Examples 3 to 4. Detailed Implementation

[0013] The method for co-catalytic pyrolysis of biomass and waste plastics according to the present invention is described in further detail below. This does not limit the scope of protection of the present invention, which is defined by the claims. Certain specific details disclosed provide a comprehensive understanding of the various disclosed embodiments. However, those skilled in the art will recognize that embodiments can be implemented using other materials, etc., without employing one or more of these specific details.

[0014] Unless the context requires otherwise, the terms "comprising" and "including" in the specification and claims shall be understood as open-ended and inclusive, meaning "including, but not limited to".

[0015] The terms "implementation," "an implementation," "another implementation," or "certain implementations" used in this specification refer to specific features, structures, or characteristics described in relation to the implementation, which are included in at least one implementation. Therefore, "implementation," "an implementation," "another implementation," or "certain implementations" do not necessarily all refer to the same implementation. Furthermore, specific features, structures, or characteristics can be combined in any way within one or more implementations. Each feature disclosed in this specification can be replaced by any alternative feature that provides the same, equivalent, or similar purpose. Therefore, unless otherwise specified, the disclosed features are merely general examples of equivalent or similar features.

[0016] The term "roasting" refers to the process of treating a substance at high temperatures in an air atmosphere.

[0017] The term "aging" refers to leaving something to stand at a certain temperature for a period of time.

[0018] In this application, the amount of aluminum source used is based on Al. 3+ count.

[0019] In this invention, the concentration unit "M" of the solution represents mol / L.

[0020] In this invention, "aviation kerosene component" refers to hydrocarbon compounds with 8 to 16 carbon atoms, that is, hydrocarbons with 8 to 16 carbon atoms.

[0021] When natural clay minerals (such as montmorillonite) are directly used for co-pyrolysis of biomass and waste plastics, they face inherent limitations in their physical structure, such as narrow interlayer spacing and low specific surface area. Although multi-level pore systems containing mesopores have been successfully constructed through acid activation, organic modification, or ion exchange, effectively alleviating the diffusion limitations of macromolecules, these methods still have significant shortcomings in the precise control of acidic sites. The modification process often struggles to balance pore structure and acidic characteristics, resulting in uneven distribution of introduced surface acidity or excessively high overall acid strength, failing to meet the requirements of high-precision directional catalysis.

[0022] In the specific reaction for preparing aviation kerosene, the mismatch between acidity and pore size is a key bottleneck limiting product selectivity. Traditional modified clays or molecular sieves (such as ZSM-5) are usually rich in strong Brønsted acid sites. This excessive acidity causes the intermediates entering the pores to undergo violent secondary cracking at high temperatures, excessively "shredding" the long-chain hydrocarbons that originally belonged to the aviation kerosene fraction into low-value C1-C4 gases, resulting in a significant decrease in liquid yield.

[0023] This application discloses a method for co-pyrolysis of biomass and waste plastics, comprising: firstly, biomass and waste plastics undergo a pyrolysis reaction, and the resulting pyrolysis gas undergoes a catalytic pyrolysis reaction in the presence of an aluminum pillared clay catalyst; wherein, the temperature of the pyrolysis reaction is 400-700 ℃, and the temperature of the catalytic pyrolysis reaction is 350-650 ℃. The preparation method of aluminum pillared clay catalyst includes: (1) adding alkaline solution dropwise into aluminum salt solution and aging it at room temperature to obtain aluminum pillared solution; (2) The polyhydroxy aluminum cations in the aluminum pillar liquid undergo ion exchange with the interlayer cations of clay to obtain an aluminum pillar clay catalyst precursor. The mass ratio of the aluminum source to the clay is 2.5-10 mmol / g. (3) The aluminum pillared clay catalyst precursor in step (2) is washed until it is neutral or close to neutral. The washed solid material is dried and calcined to obtain the aluminum pillared clay catalyst.

[0024] The production of aviation kerosene through single catalytic cracking of waste plastics or biomass both have certain drawbacks. Waste plastic cracking suffers from low selectivity in aviation kerosene due to its wide carbon number distribution and high content of light components. Biomass, due to its natural chemical composition, has high oxygen content in its pyrolysis products, resulting in low calorific value and unstable chemical properties, making it difficult to utilize directly. The inventors have discovered that a co-cracking technology combining biomass and waste plastics effectively compensates for the high oxygen content of biomass by utilizing the hydrogen-rich characteristics of waste plastics. Through a hydrogen transfer mechanism, a synergistic effect is triggered, significantly improving the yield of aviation kerosene components under the catalytic action of the aluminum-pillared clay catalyst prepared in this application.

[0025] Waste plastics include polyethylene, polypropylene, polystyrene, polybutene, or polymethylpentene plastics. Biomass includes crop straw (e.g., reed, corn straw, wheat straw, rice straw, soybean straw, cotton straw, etc.), agricultural processing by-products (e.g., walnut shells, nutshells, rice husks, corn cobs, peanut shells, cottonseed husks, sugarcane bagasse, beet pulp, etc.), forestry biomass (e.g., mulberry branches, shrub coppicings, branches, tree tops, bark, etc., as well as sawdust, shavings, and other wood processing residues), microalgae biomass, energy grasses, non-edible oil crops and their processing residues, and industrial organic waste rich in lignin or oils.

[0026] Biomass includes one or more of the following: walnut shells, mulberry branches, golden nut shells, flue-cured tobacco stalks, dried green husks, biomass pellets, pine nut shells, and reeds.

[0027] In some implementations, the mass ratio of waste plastics to biomass is 5:1 to 1:5.

[0028] The mass ratio can be 5:1, 4:1, 3:1, 2:1, 1:1, 1:2, 1:3, 1:4 or 1:5.

[0029] Optional waste plastic to biomass mass ratio: 2:1 – 1:2 Optionally, the waste plastic is polyethylene plastic, with a mass ratio of polyethylene plastic to biomass of approximately 1:1 or equal to 1:1. Catalytic cracking is carried out under the action of an aluminum-pillared clay catalyst at a temperature of 450-600 ℃.

[0030] The weight-average molecular weight of waste plastics is approximately 80,000 to 150,000.

[0031] In the co-pyrolysis process of biomass and waste plastics, the biomass and waste plastics synergistically interact under the action of an aluminum-pillared clay catalyst, resulting in a higher yield of aviation kerosene. Compared with the pyrolysis reactions of biomass or waste plastics alone, the co-pyrolysis of biomass and waste plastics can significantly improve the selectivity and quality of aviation kerosene production.

[0032] Alternatively, after the mixture of biomass and waste plastics undergoes pyrolysis, the resulting pyrolysis gas is subjected to catalytic cracking under the action of an aluminum-pillared clay catalyst. Typically, the temperature of the pyrolysis reaction is higher than the reaction temperature of the catalytic cracking.

[0033] The selectable pyrolysis reaction temperature is 400-700 ℃; the catalytic cracking reaction temperature is 350-650 ℃.

[0034] Preferably, the pyrolysis reaction temperature is 500-540℃, for example, 540℃.

[0035] Preferably, the temperature of the catalytic cracking reaction is 450-510℃, for example, 500℃.

[0036] The total reaction time for the pyrolysis and catalytic cracking of the biomass-waste plastic mixture is 15-50 minutes. For example, the total reaction time is 30-35 minutes.

[0037] The pyrolysis reaction time does not need to be specially controlled. It is only necessary to set it within the above temperature range, and the generated pyrolysis gas can react with the catalyst at the pyrolysis temperature. The total reaction time can be controlled within 15-50 minutes.

[0038] The typical pyrolysis products are mixed hydrocarbons with a wide carbon number distribution (such as a mixture of oils and waxes with C5-C40+).

[0039] Aluminum sources include aluminum hydroxychloride, aluminum nitrate, aluminum sulfate, and / or aluminum chloride hexahydrate.

[0040] In the preparation method of aluminum-pillared clay catalyst, in step (2), clay raw material is added to the pre-prepared aluminum-pillared liquid, and the exchange of interlayer cations and the directional assembly of the pillared precursor are completed under vigorous stirring conditions. In this process, since the hydrolysis and polymerization process of aluminum source has been completed in the homogeneous system, the resulting Keggin ions have a charge density as high as +7 valence, and the driving force for the exchange of interlayer cations is significantly increased, which promotes the rapid migration and locking of Keggin ions into the clay interlayer. However, compared with the traditional in-situ hydrolysis intercalation method (i.e., mixing clay and aluminum salt and then dripping alkali), the stepwise synthesis strategy adopted in this method effectively avoids the excessive local alkalinity caused by direct contact of alkali solution with the clay surface, fundamentally avoiding competitive hydrolysis of aluminum source on the outer surface of clay and precipitation of inactive aluminum hydroxide precipitate, and significantly improving the utilization rate of active Keggin ions. In traditional in-situ methods, the formation and intercalation of aluminum species occur simultaneously, often leading to pore blockage and structural disorder. The pre-formed liquid phase intercalation method provided by this invention ensures the uniformity of interlayer pillar species and structural integrity.

[0041] In some embodiments, in step (2), the aluminum pillar liquid undergoes ion exchange with the interlayer cations of clay under stirring at a speed of 200~600 rpm.

[0042] The stirring speed can be selected as 200~400 rpm, for example, 400 rpm.

[0043] Alternatively, the ion exchange reaction in step (2) can be carried out in the range of 2 h to 36 h.

[0044] Optionally, in step (2), the aluminum pillar liquid and clay undergo ion exchange reaction for 24 hours under stirring at a speed of 400 rpm.

[0045] The aluminum pillar-supported liquid direct intercalation method of the present invention can significantly improve the specific surface area while optimizing the pore size distribution of the catalyst. At the same time, it constructs a "mesoporous-acidic" synergistic active center, which is more conducive to the precise control of the carbon chain breakage position and improves the directional conversion performance of the catalyst.

[0046] Compared with the traditional multi-step modified pillar method, the present invention simplifies the synthesis path. "The clay raw material can be used directly in the form of raw ore or crude purified powder without pretreatment. In step (2), the clay swells and undergoes ion exchange, which effectively shortens the preparation process and has the potential for industrial-scale production.

[0047] In some embodiments, the aluminum source includes: aluminum hydroxychloride, aluminum nitrate, aluminum sulfate, and / or aluminum chloride.

[0048] Alternatively, the aluminum source can be aluminum chloride, such as aluminum chloride hexahydrate.

[0049] This application uses aluminum chloride as the aluminum source, taking advantage of its ease of forming a high-charge Keggin structure (Al). 13 The properties of polyhydroxy cationic polymers enable the construction of highly thermally stable rigid alumina pillars between clay layers. This not only significantly increases the interlayer spacing and constructs a microporous-mesoporous hierarchical pore system, greatly improving the specific surface area to overcome the mass transfer limitations of macromolecules, but more importantly, it introduces moderately strong acidic sites, mainly Lewis acids, achieving precise control over the "mildening" of catalyst acidity. The synergistic shape-selective effect generated by this specific interlayer pore size and suitable acid strength effectively inhibits the violent secondary cracking of reaction intermediates at high temperatures, ensuring that the cracking reaction depth is precisely stopped at the C8-C16 fraction stage. Thus, while ensuring excellent anti-coking performance and hydrothermal stability, it significantly improves the selectivity and yield of the target product, aviation kerosene.

[0050] Aluminum-pillared clay catalysts can be used in the co-pyrolysis of biomass and waste plastics to improve the selectivity of aviation kerosene components.

[0051] The inorganic base of this invention is sodium hydroxide.

[0052] In some embodiments, in step (1), the molar ratio of aluminum source to NaOH is 1:(1-4).

[0053] The amounts of aluminum source and inorganic alkali used are respectively based on Al 3+ Based on the NaOH content, in the aluminum pillar of step (1), Al 3+ The concentration is 0.1-0.4 mol / L.

[0054] Optional, in the aluminum struts of step (1), Al 3+ Concentrations of 0.1-0.25 mol / L, for example, Al 3+ The concentration is approximately or equal to 0.1 mol / L or 0.2 mol / L.

[0055] In some embodiments, in step (2), the mass ratio of the aluminum source to the clay is 2.5-10 mmol / g.

[0056] Alternatively, the mass ratio of the aluminum source to the clay can be 2.5-6 mmol / g, for example, the mass ratio of the aluminum source to the clay can be equal to or approximately 5 mmol / g.

[0057] The clay of this invention can be bentonite and / or montmorillonite.

[0058] Preferably, the clay of the present invention is bentonite.

[0059] Strict control of OH - / Al 3+ Under the specified molar ratio and aluminum / clay ratio, assembly is performed using a pre-formed aluminum-pillared liquid direct intercalation method, which does not damage the natural layered crystal structure of clay (such as lamination collapse or amorphization). The highly ordered and robust alumina-pillared structure ensures the hydrothermal stability of the catalyst in the high-temperature co-pyrolysis reaction. At the same time, the directional loading process of the active precursor is more conducive to the precise control of the mesopore size and surface acid strength distribution of the aluminum-pillared clay catalyst, thereby maximizing the yield of aviation kerosene components.

[0060] In some embodiments, the drying temperature of the solid material in step (3) is 60-110 °C. Alternatively, the drying temperature is 80 °C.

[0061] Under these conditions, the moisture in the washed solid material is removed as much as possible, and the drying time is not limited, as long as the moisture content is below a certain range. For example, drying at 80 ℃ for 12 hours is sufficient to achieve the desired drying effect.

[0062] In some embodiments, the calcination temperature of the dried solid material is between 300 ℃ and 600 ℃. Alternatively, the calcination temperature is 550 ℃.

[0063] Preferably, the roasting time is 2 h-6 h.

[0064] The aluminum pillared catalyst obtained by the above preparation method has tunable pore structure and acid properties. By constructing open mesoporous channels, it can effectively remove the mass transfer and diffusion limitations of macromolecular reactants and intermediates, and optimize the hydrogen transfer and co-pyrolysis process of biomass and waste plastics. In particular, by using suitable mesoporous pore size matching and optimized acid distribution, it can effectively suppress excessive pyrolysis (gas production) and side reactions such as polymerization and coking, promote the rapid diffusion and desorption of C8-C16 target fractions, and improve the selectivity of aviation kerosene.

[0065] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Experimental methods in the following embodiments, unless otherwise specified, are generally performed under conventional conditions or as recommended by the manufacturer. Unless otherwise stated, all percentages, ratios, proportions, or parts are by weight.

[0066] In the following examples and comparative examples, aluminum chloride hexahydrate was purchased from Sinopharm Reagent Company; sodium hydroxide was purchased from Sinopharm Reagent Company; bentonite and montmorillonite were purchased from Shanghai Maclean Biochemical Technology Co., Ltd. The waste plastic PE used in the following examples and comparative examples was low-density polyethylene produced by Fengtai Plastic Raw Materials Co., Ltd., a white powder with a crystallinity of 50%~65%, a softening point of 90-100℃, and a molecular weight of 150,000; PS (melt coefficient of 8 g / 10 min, weight-average molecular weight of approximately 150,000-250,000) was general-purpose polystyrene produced by Fengtai Plastic Raw Materials Co., Ltd., which was dried before the co-pyrolysis reaction. The biomass reeds, golden nut shells, walnut shells, and mulberry branches used in the following examples were from Dali, Yunnan, and were dried and crushed before the co-pyrolysis reaction.

[0067] Example 1 First, a certain amount of solid aluminum chloride hexahydrate was dissolved in deionized water, and the solution was stirred and heated to 70 °C. Then, a certain amount of 1 M sodium hydroxide solution was slowly added dropwise to the aluminum chloride solution. The resulting solution contained OH-. - With Al 3+ Molar ratio between ions OH - Al 3+ =2.0:1, aluminum ion concentration of 0.2 mol / L; after aging at 35 ℃ for 24 h, a certain amount of bentonite solid raw material was added, with each gram of bentonite corresponding to an aluminum ion feed amount of 5 mmol (i.e., Al). 3+ The mass ratio of the substance to clay was 5 mmol / g. The resulting suspension was stirred at 35 °C and 400 rpm for 24 h, then the solid product was recovered by centrifugation and repeatedly washed with deionized water until neutral. It was then dried at 80 °C for 12 h and finally calcined at 550 °C in air for 3 h to obtain the aluminum pillared clay catalyst.

[0068] Catalytic cracking reaction: The experiment was conducted using a two-stage fixed-bed reactor. The first stage reactor was the pyrolysis zone, and the second stage reactor was the catalytic cracking zone. First, 1 g of the aluminum-pillared clay catalyst sample prepared in this example was placed in the isothermal zone of the second stage reactor and preheated to 500 °C; simultaneously, the pyrolysis zone of the first stage reactor was preheated and stabilized at 540 °C. After the temperature stabilized, 1 g of *Arundo donax* and low-density polyethylene (mass ratio 1:1) were mixed evenly and quickly placed into the 540 °C pyrolysis zone. Under a nitrogen atmosphere, the raw materials rapidly underwent non-catalytic pyrolysis in the first stage reactor, and the resulting gaseous intermediate products entered the catalyst bed with the carrier gas for catalytic cracking. The entire pyrolysis and catalytic reaction process lasted approximately 35 min. The product distribution after the cracking reaction is shown in the appendix. Figure 3 and 4 .

[0069] Example 2 The experimental steps in this embodiment are the same as in Example 1, except that bentonite is replaced with montmorillonite to obtain an aluminum-pillared clay catalyst. The molar ratios and amounts of each raw material in the reaction system of this embodiment are as follows: OH - Al 3+ =2.0:1, the aluminum ion dosage per gram of montmorillonite is 5 mmol (i.e., Al). 3+ The mass ratio of the substance to the clay was 5 mmol / g, the initial aluminum ion concentration was 0.2 mol / L, and the stirring speed was controlled at 400 rpm during ion exchange.

[0070] Catalytic cracking reaction: 1 g of the aluminum pillared clay catalyst sample prepared in this example was placed in the isothermal zone of the second-stage reactor. Other reactants, reaction conditions, and other parameters were carried out according to the catalytic cracking reaction in Example 1. The product distribution after the cracking reaction is shown in the appendix. Figure 3 and 4 .

[0071] Example 3 The experimental steps in this embodiment are the same as in Example 1, except that the initial aluminum ion concentration is increased from 0.2 mol / L to 0.4 mol / L, resulting in an aluminum-pillared clay catalyst. The molar ratios and amounts of each raw material in the reaction system of this embodiment are as follows: OH - Al 3+ =2.0:1, the aluminum ion dosage per gram of bentonite is 5 mmol (i.e., Al 3+ The mass ratio of the substance to the clay was 5 mmol / g, the initial aluminum ion concentration was 0.4 mol / L, and the stirring speed was controlled at 400 rpm during ion exchange.

[0072] Catalytic cracking reaction: 1 g of the aluminum pillared clay catalyst sample prepared in this example was placed in the isothermal zone of the second-stage reactor. Other reactants, reaction conditions, and other parameters were carried out according to the catalytic cracking reaction in Example 1. The product distribution after the cracking reaction is shown in the appendix. Figure 3 and 4 .

[0073] Example 4 The experimental steps in this embodiment are the same as in Example 1, except that the initial aluminum ion concentration is reduced from 0.2 mol / L to 0.1 mol / L, resulting in an aluminum-pillared clay catalyst. The molar ratios and amounts of each raw material in the reaction system of this embodiment are as follows: OH - Al 3+ =2.0:1, the aluminum ion dosage per gram of bentonite is 5 mmol (i.e., Al 3+ The mass ratio of the substance to the clay was 5 mmol / g, the initial aluminum ion concentration was 0.1 mol / L, and the stirring speed was controlled at 400 rpm during ion exchange.

[0074] Catalytic cracking reaction: 1 g of the aluminum pillared clay catalyst sample prepared in this example was placed in the isothermal zone of the second-stage reactor. Other reactants, reaction conditions, and other parameters were carried out according to the catalytic cracking reaction in Example 1. The product distribution after the cracking reaction is shown in the appendix. Figure 3 and 4 .

[0075] Example 5 The experimental steps in this embodiment are the same as in Example 1, except that the amount of bentonite is increased to obtain an aluminum-pillared clay catalyst. The molar ratio and amount of each raw material in the reaction system of this embodiment are as follows: OH - Al 3+ =2.0:1, the aluminum ion dosage per gram of bentonite is 2.5 mmol (i.e., Al). 3+ The mass ratio of the substance to the clay was 2.5 mmol / g, the initial aluminum ion concentration was 0.2 mol / L, and the stirring speed was controlled at 400 rpm.

[0076] Catalytic cracking reaction: 1 g of the aluminum pillared clay catalyst sample prepared in this example was placed in the isothermal zone of the second-stage reactor. Other reactants, reaction conditions, and other parameters were carried out according to the catalytic cracking reaction in Example 1. The product distribution after the cracking reaction is shown in the appendix. Figure 3 and 4 .

[0077] Example 6 This embodiment uses the same catalyst as Example 1. The difference is that the waste plastic in the raw materials is replaced with general-purpose polystyrene, a type of polystyrene, instead of low-density polyethylene (LDPE).

[0078] Catalytic cracking reaction: The experiment was conducted using a two-stage fixed-bed reactor. The first stage reactor was the pyrolysis zone, and the second stage reactor was the catalytic cracking zone. First, 1 g of the aluminum-pillared clay catalyst sample prepared in Example 1 was placed in the isothermal zone of the second stage reactor and preheated to 500 °C; simultaneously, the pyrolysis zone of the first stage reactor was preheated and stabilized at 540 °C. After the temperature stabilized, 1 g of *Arundo donax* and general-purpose polystyrene (mass ratio 1:1) were mixed evenly and quickly placed into the 540 °C pyrolysis zone. Under a nitrogen atmosphere, the raw materials rapidly underwent non-catalytic pyrolysis in the first stage reactor, and the resulting gaseous intermediate products entered the catalyst bed with the carrier gas for catalytic cracking. The entire pyrolysis and catalytic reaction process lasted approximately 35 min. The product distribution after the cracking reaction is shown in the appendix. Figure 6 and 7 .

[0079] Example 7 This embodiment uses the same catalyst as in Example 1. The difference is that the biomass in the raw materials is replaced with mulberry branches, a type of forestry biomass, instead of agricultural crop straw such as reeds.

[0080] Catalytic cracking reaction: The experiment was conducted using a two-stage fixed-bed reactor. The first stage reactor was the pyrolysis zone, and the second stage reactor was the catalytic cracking zone. First, 1 g of the aluminum-pillared clay catalyst sample prepared in Example 1 was placed in the isothermal zone of the second stage reactor and preheated to 500 °C; simultaneously, the pyrolysis zone of the first stage reactor was preheated and stabilized at 540 °C. After the temperature stabilized, 1 g of mulberry twigs and low-density polyethylene (mass ratio 1:1) were mixed evenly and quickly placed into the 540 °C pyrolysis zone. Under a nitrogen atmosphere, the raw materials rapidly underwent non-catalytic pyrolysis in the first stage reactor, and the resulting gaseous intermediate products entered the catalyst bed with the carrier gas for catalytic cracking. The entire pyrolysis and catalytic reaction process lasted approximately 35 min. The product distribution after the cracking reaction is shown in the appendix. Figure 6 and 7 .

[0081] Comparative Example 1 The experimental procedures in this comparative example are the same as in Example 1, except that the amount of bentonite is increased and the initial aluminum ion concentration is increased from 0.2 mol / L to 0.4 mol / L, resulting in an aluminum-pillared clay catalyst. The molar ratios and amounts of each raw material in the reaction system of this example are as follows: OH - Al 3+ =2.0:1, the aluminum ion dosage per gram of bentonite is 2.5 mmol (i.e., Al). 3+The mass ratio of the substance to the clay was 2.5 mmol / g, the initial aluminum ion concentration was 0.4 mol / L, and the stirring speed was controlled at 400 rpm during ion exchange.

[0082] Catalytic cracking reaction: 1 g of catalyst sample was placed in the isothermal zone of the second stage reactor. Other reactants, reaction conditions, and other parameters were carried out according to the catalytic cracking reaction in Example 1. The product distribution after the cracking reaction is shown in Appendix. Figure 3 and 4 .

[0083] Comparative Example 2 The experimental procedures in this comparative example are the same as in Example 1, except that bentonite is replaced with montmorillonite and the initial aluminum ion concentration is increased from 0.2 mol / L to 0.4 mol / L, resulting in an aluminum-pillared clay catalyst. The molar ratios and amounts of each raw material in the reaction system of this comparative example are as follows: OH - Al 3+ =2.0:1, the aluminum ion dosage per gram of montmorillonite is 5 mmol (i.e., Al). 3+ The mass ratio of the substance to the clay was 5 mmol / g, the initial aluminum ion concentration was 0.4 mol / L, and the stirring speed was controlled at 400 rpm during ion exchange.

[0084] Catalytic cracking reaction: 1 g of catalyst sample was placed in the isothermal zone of the second stage reactor. Other reactants, reaction conditions, and other parameters were carried out according to the catalytic cracking reaction in Example 1. The product distribution after the cracking reaction is shown in Appendix. Figure 3 and 4 .

[0085] Comparative Example 3 This comparative example uses the same catalyst as Example 1. The difference is that the raw material is replaced by pure waste plastic low-density polyethylene instead of a mixture of reed and low-density polyethylene.

[0086] Catalytic cracking reaction: The experiment was conducted using a two-stage fixed-bed reactor. The first stage reactor was the pyrolysis zone, and the second stage reactor was the catalytic cracking zone. First, 1 g of the aluminum-pillared clay catalyst sample prepared in Example 1 was placed in the isothermal zone of the second stage reactor and preheated to 500 °C; simultaneously, the pyrolysis zone of the first stage reactor was preheated and stabilized at 540 °C. After the temperature stabilized, 1 g of low-density polyethylene was rapidly placed into the 540 °C pyrolysis zone. Under a nitrogen atmosphere, the raw material rapidly underwent non-catalytic pyrolysis in the first stage reactor, and the resulting gaseous intermediate products entered the catalyst bed with the carrier gas for catalytic cracking. The entire pyrolysis and catalytic reaction process lasted approximately 35 min. The product distribution after the cracking reaction is shown in the appendix. Figure 6 and 7 .

[0087] Comparative Example 4 This comparative example uses the same catalyst as Example 1. The difference is that the raw material is replaced by pure biomass reed instead of a mixture of reed and low-density polyethylene.

[0088] Catalytic cracking reaction: The experiment was conducted using a two-stage fixed-bed reactor. The first stage reactor was the pyrolysis zone, and the second stage reactor was the catalytic cracking zone. First, 1 g of the aluminum-pillared clay catalyst sample prepared in Example 1 was placed in the isothermal zone of the second stage reactor and preheated to 500 °C; simultaneously, the pyrolysis zone of the first stage reactor was preheated and stabilized at 540 °C. After the temperature stabilized, 1 g of *Arundo donax* was rapidly placed into the 540 °C pyrolysis zone. Under a nitrogen atmosphere, the raw material rapidly underwent non-catalytic pyrolysis, and the resulting gaseous intermediate products entered the catalyst bed with the carrier gas for catalytic cracking. The entire pyrolysis and catalytic reaction process lasted approximately 35 min. The product distribution after the cracking reaction is shown in the appendix. Figure 6 and 7 .

[0089] Experimental Example 1 The catalysts prepared in Examples 1 to 5 and Comparative Examples 1 to 2 were subjected to nitrogen physical adsorption-desorption analysis and temperature-programmed desorption analysis. The results are shown in Appendix. Figure 1 And Table 1.

[0090] The catalysts prepared in Examples 1 to 5 and Comparative Examples 1 to 2 were analyzed by NH3-TPD (ammonia temperature-programmed desorption), and the results are shown in the appendix. Figure 2 And Table 2.

[0091] Nitrogen physical adsorption-desorption analysis was performed using a Micromeritics ASAP 2460 instrument. Ammonia temperature-programmed desorption analysis was performed using a Micromeritics AutoChem II instrument.

[0092] Table 1 Table 1 shows the specific surface area and porosity characteristics of the catalysts prepared in Examples 1 to 5 and Comparative Examples 1 to 2.

[0093] Table 2 Table 2 shows the acidity characteristics of the catalysts prepared in Examples 1 to 5 and Comparative Examples 1 to 2.

[0094] As attached Figure 1As shown, the nitrogen adsorption-desorption isotherms of the pillared clay samples exhibit typical Type IV characteristics, with a significant hysteresis loop appearing in the medium- and high-pressure regions. The rapid increase in adsorption in the low-pressure region corresponds to the filling of interlayer micropores, while the presence of the hysteresis loop indicates the formation of a rich mesoporous structure in the material. This significant pore feature confirms that the pillaring agent successfully inserted and effectively expanded the interlayer domains of the clay, transforming it from a relatively dense layered stacking state into a two-dimensional layered porous framework with a high specific surface area, thereby effectively improving the accessibility of surface active sites.

[0095] Depend on Figure 2 It is evident that as the Al loading per gram of clay decreases, the number of weak and medium acids on the catalyst surface decreases, but the number of key strong acid sites increases significantly. In the co-cracking reaction, although the increased strong acid can improve the conversion rate of waste plastics, excessively high strong acid density can trigger severe secondary cracking of the middle fraction; simultaneously, the loss of weak and medium acids weakens the catalyst's ability to regulate product chain length, leading to a decrease in jet fuel component yield. Example 1: By controlling a suitable Al... 3+ The ratio of the amount of substance to the mass of clay was optimized to improve the density and uniformity of the interlayer struts, thereby controlling the density of surface acidic sites within a suitable range and effectively avoiding excessive product decomposition caused by excessively dense active sites or excessively strong local acidity. Changes in the Al ion concentration in the preparation solution were also sensitive. When the concentration increased (above the optimal value), the excessively high ion concentration significantly reduced the activity of water molecules in the interlayer and altered the osmotic pressure balance, inhibiting the full swelling of the clay layer and the effective opening of the interlayer domains. This resulted in the inability to expose and utilize the intrinsic acidic sites deep within the layer, leading to a significant decrease in the amount of strong acid. Conversely, when the concentration decreased, it facilitated the full swelling and dispersion of the clay layer. This good interlayer openness ensured the effective exposure of the intrinsic acidic sites (mainly contributing strong acid) in the clay layer, resulting in a significant increase in the amount of strong acid, while the amount of weak and medium acid remained relatively unchanged. When the clay matrix was replaced with montmorillonite from bentonite, the inherent acid strength basis of the layer changed, leading to a significant reduction in the intrinsic strong acidic sites from the clay layer. In some implementations, by synergistically adjusting the above-mentioned preparation pillar parameters and clay matrix type, the precise control of acid distribution on the catalyst surface is achieved, and the adjustable range of the ratio of weak, medium and strong acids covers 0.32 to 20.71.

[0096] Experiment Example 2 The catalysts prepared in Examples 1 to 5 and Comparative Examples 1 to 2 were used for the co-pyrolysis of biomass and waste plastics. See attached diagrams for gas-liquid-solid yield and liquid-phase carbon number distribution. Figure 3 Appendix Figure 4 And Table 3. See attached diagrams for gas-liquid-solid yield and liquid phase carbon number distribution of Examples 6 and 7 and Comparative Examples 3 and 4. Figure 6 Appendix Figure 7See Table 4. Liquid phase product analysis was performed using a Celian 456C gas chromatograph from Tianmei Chemical Co., Ltd. The detection results for different biomass components are shown in Table 5.

[0097] Table 3 Table 3 shows the gas, liquid, and solid yields and aviation kerosene component yields for Examples 1 to 5 and Comparative Examples 1 to 2.

[0098] : Jet fuel component yield (in wt%).

[0099] The sum of peak areas for components from C8 to C16. This refers to the total area of ​​all peaks corresponding to retention times from C8 to C16 on a gas chromatogram.

[0100] Total peak area. This is the sum of the areas of all detected components in the chromatogram.

[0101] Liquid yield. This refers to the percentage by mass of the liquid product generated during the reaction process relative to the total feed.

[0102] Table 3 shows that the products of co-pyrolysis of biomass and waste plastics include: alkanes, olefins, aromatics, oxygen-containing substances, and C16+ components. The order of jet fuel component yield is as follows: Example 1 (57.29%) > Example 4 (55.12%) > Example 3 (53.29%) > Example 2 (48.31%) > Example 5 (42.23%) > Comparative Example 1 (36.15%) > Comparative Example 2 (30.12%). It is worth noting that although Example 3 achieved the highest total liquid yield (73.72%), its jet fuel component proportion was significantly lower than that of Example 1, and its C16+ heavy component content was higher, indicating that its pyrolysis capacity was relatively insufficient. Conversely, Example 1 maximized the jet fuel component yield while maintaining a high liquid yield (69.34%), indicating that the catalyst can more accurately convert macromolecular raw materials into jet fuel.

[0103] Experimental data revealed a significant "volcano-like" structure-activity relationship between the catalyst's acidity characteristics and jet fuel yield. In the complex reaction network of biomass and waste plastic co-pyrolysis, Example 1 occupies two peak positions on the volcano diagram (…). Figure 5This is attributed to the precise control of acid distribution, achieving a perfect balance between "chain-breaking cracking" and "hydrogen transfer synergy." When this ratio is maintained within the optimal range (2.0-2.5), an ideal "dual-function synergistic" environment is constructed on the catalyst surface. A suitable amount of strong acid sites acts as "primary scissors," responsible for cleaving the high-molecular-weight C-C bonds of waste plastics (PE); while abundant medium-strong acid sites act as "hydrogen transfer stations," not only catalyzing the dehydration and deoxygenation of oxygen-containing intermediates in biomass, but more importantly, promoting hydrogen transfer from hydrogen-rich fragments generated by waste plastic cracking to hydrogen-deficient free radicals in biomass. This synergistic effect effectively stabilizes the intermediate products, locking them within the C8-C16 jet fuel range. When the ratio is too low (too high a proportion of strong acid), the acidic environment becomes too harsh. Excessive strong acid sites lead to uncontrollable secondary cracking of primary cracking products, generating large amounts of gas and aromatic hydrocarbon condensation and coking due to deep dehydrogenation. When the ratio is too high (lacking strong acid), the system lacks the activation energy required to cleave long-chain alkanes. The incomplete degradation of waste plastic macromolecules results in a large amount of heavy wax C16+ remaining in the product, preventing it from entering the aviation kerosene fraction. Based on this, this study further defines the effective range of (weak acid + medium acid) / strong acid ratio for aviation kerosene preparation as 0.3-20. Once the ratio exceeds the upper limit of this range (e.g., 25.44 for the aluminum pillared clay catalyst sample prepared in Comparative Example 2), the catalyst essentially loses its ability to initiate the cracking of polyolefin macromolecules because the density of strong acid sites has dropped below the critical value. This not only leads to the accumulation of heavy components but also causes a sharp decrease in the total yield of liquid hydrocarbons, making it virtually impossible to obtain high-yield aviation kerosene components under these conditions.

[0104] Generally, the formation of high-quality aviation kerosene components depends on the primary cracking of macromolecules and the moderate isomerization of intermediate products. The superior performance of Example 1 is attributed to its constructed gradient acid structure of "rich in medium acid and stable in strong acid". An appropriate amount of strong acid sites acts as a "starter" for the dehydrogenation and carbon chain breaking of waste plastics, ensuring a high conversion rate; while the abundant medium-strong acid sites effectively inhibit excessive cracking reactions. As shown in the figure, Example 1 significantly reduced the C16+ heavy component while maintaining a low gas yield (17.24%), with the carbon number distribution of its products concentrated in the C8-C16 range. This indicates that this acid distribution structure is beneficial for reducing continuous secondary cracking reactions (generating gas) and condensation reactions (generating coke / solids; Example 1 had the lowest solids yield of 6.22%), thereby promoting the targeted formation of high-value-added aviation kerosene components.

[0105] Table 4 Table 4 shows the gas, liquid, and solid yields and jet fuel component yields after catalytic cracking of different reaction feedstocks in Examples 1, 6 to 7 and Comparative Examples 3 to 4.

[0106] Compared with individual pyrolysis, the co-pyrolysis system of biomass and waste plastics (PE) exhibits a significant synergistic chemical effect. Figure 6 In individual pyrolysis, biomass products have high oxygen content and low calorific value, while PE pyrolysis products have an excessively high proportion of light components. After co-pyrolysis, the moderately strong Lewis acid sites unique to the aluminum-pillared clay catalyst prepared in Example 1 act as a "molecular bridge," efficiently inducing PE, as a hydrogen-rich donor, to transfer hydrogen to the hydrogen-deficient oxygen-containing intermediate of biomass. This synergistic effect not only significantly reduces the oxygen-containing compounds in the products but also inhibits the formation of C16+ heavy components through Diels-Alder cyclization and moderate pyrolysis, promoting the directional enrichment of C8-C16 aviation kerosene components from the disordered state of individual pyrolysis, achieving a "1+1>2" quality and efficiency improvement. More importantly, the catalyst exhibits excellent feedstock versatility: when crop straw (Reed) is replaced with forestry biomass (Mulberry) with a more dense wood fiber structure, the co-pyrolysis system of mulberry and PE still maintains extremely high reaction efficiency, with a liquid yield of 67.09% and an aviation kerosene component yield as high as 53.62%. This fully demonstrates that the catalyst described in this invention can not only efficiently process crop straw, but is also suitable for the resource utilization of forestry biomass, and has broad industrial application potential.

[0107] Further comparison of the co-pyrolysis behavior of different waste plastics ( Figure 7 As can be seen, unlike the "Reed + PE" system, which tends to generate aliphatic hydrocarbons with a broad carbon number distribution (C7-C14), the "Reed + PS" system exhibits a unique product "focusing" effect and aromatization characteristics. Data in the figure shows that the carbon number of the products in this system is highly concentrated in the C7-C10 range, and the components are dominated by high-purity aromatic hydrocarbons. This stems from the directional depolymerization and retention of styrene units in the PS molecule at the acidic sites of the catalyst. This directional enrichment of high-density aromatic components provides an ideal blending component for the preparation of high-quality aviation kerosene.

[0108] In summary, regardless of the type of biomass raw material, such as crop straw (reed) or forestry biomass (mulberry branches), or the type of waste plastic with different structures, such as polyolefin (PE) or polyaromatic hydrocarbon (PS), the catalyst described in this invention exhibits excellent raw material versatility and catalytic stability, proving that it can flexibly cope with complex and varied actual waste components and efficiently produce high-quality aviation kerosene.

[0109] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.

Claims

1. A method for co-pyrolyzing biomass and waste plastics, comprising: Biomass and waste plastics were catalytically cracked under the action of aluminum-supported clay catalyst at a reaction temperature of 450-600 ℃. The preparation method of aluminum pillared clay catalyst includes: (1) adding alkaline solution dropwise into aluminum salt solution and aging it at room temperature to obtain aluminum pillared solution; (2) The polyhydroxy aluminum cations in the aluminum pillar liquid undergo ion exchange with the interlayer cations of clay to obtain an aluminum pillar clay catalyst precursor. The mass ratio of the aluminum source to the clay is 2.5-10 mmol / g. (3) The aluminum pillared clay catalyst precursor in step (2) is washed until it is neutral or close to neutral. The washed solid material is dried and calcined to obtain the aluminum pillared clay catalyst.

2. The preparation method according to claim 1, characterized in that, The mass ratio of waste plastics to biomass is 5:1 – 1:5; Preferably, the mass ratio of waste plastics to biomass is 2:1 – 1:2; Preferably, the waste plastics include polyethylene, polypropylene, polystyrene, polybutene, or polymethylpentene plastics; Preferably, biomass includes crop straw, agricultural product processing by-products, forestry biomass, microalgae biomass, energy grass plants, non-edible oil crops and their processing residues, and industrial organic waste rich in lignin or oils. More preferably, the biomass includes one or more of the following: walnut shells, mulberry branches, golden nut shells, flue-cured tobacco stalks, dried green bark, pine nut shells, and reed.

3. The preparation method according to claim 1 or 2, characterized in that, A mixture of biomass and waste plastics undergoes pyrolysis. The resulting pyrolysis gas is then subjected to catalytic cracking at a temperature of 350-650 ℃ under the action of an aluminum-pillared clay catalyst. The temperature of the pyrolysis reaction is higher than that of the catalytic cracking reaction. Preferably, the temperature of the pyrolysis reaction is 400-700 °C; Preferably, the temperature of the pyrolysis reaction is 500-540℃ (preferably 540℃); Preferably, the temperature of the catalytic cracking reaction is 450-510℃ (preferably 500℃).

4. The preparation method according to claim 3, characterized in that, The total reaction time for the pyrolysis and catalytic cracking of the biomass-waste plastic mixture is 15-50 min; Preferably, the total reaction time is 30-35 min.

5. The preparation method according to any one of claims 1-4, characterized in that, In the aluminum column support of step (1), Al 3+ The concentration is 0.1-0.4 mol / L; Preferably, in the aluminum column support of step (1), Al 3+ The concentration is 0.1-0.25 mol / L. More preferably, in the aluminum column support of step (1), Al 3+ The concentration is 0.2 mol / L.

6. The preparation method according to any one of claims 1-5, characterized in that, Aluminum sources include aluminum hydroxychloride, aluminum nitrate, aluminum sulfate, and / or aluminum chloride; Preferably, the molar ratio of aluminum source to NaOH is 1:(1-4).

7. The preparation method according to any one of claims 1-5, characterized in that, In step (2), Al 3+ The mass ratio of the substance to the clay is 2.5-10 mmol / g; Preferably, Al 3+ The mass ratio of the substance to the clay is 2.5-6 mmol / g (preferably 5 mmol / g). Preferably, the clay includes montmorillonite and / or bentonite; Further optimization yielded bentonite as the clay.

8. The preparation method according to any one of claims 1-7, characterized in that, In step (1), the hydrolysis-polymerization reaction temperature is 50-90 ℃; Preferably, in step (1), the hydrolysis polymerization reaction time is 0.5 h-2 h.

9. The preparation method according to any one of claims 1-7, characterized in that, In step (2), the stirring speed is 200~600 rpm; Preferably, the stirring speed is 200~400 rpm.

10. The preparation method according to any one of claims 1-7, characterized in that, In step (3), the drying temperature of the solid material is 60-110 ℃; Preferably, the calcination temperature of the dried solid material is 300-600 ℃; The preferred method is to roast for 2-6 hours.

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