A coal and waste plastic co-pyrolysis catalyst Ni / Ce / Zr-@USY and a preparation method thereof

Abstract

The application discloses a coal and waste plastic co-pyrolysis catalyst Ni / Ce / Zr-@USY and a preparation method thereof, and is prepared according to the following steps: step (one), pretreatment and surface modification of microporous USY, step (two), USY surface seedling, step (three), synthesis of mesoporous USY shell layer precursor gel, step (four), hydrothermal crystallization and shell growth, step (five), post-treatment and activation, and step (six), ethanol impregnation method for synthesizing the Ni / Ce / Zr-@USY with a core-shell structure. The application firstly grafts a layer of seeds capable of inducing mesoporous USY growth on the surface of a commercial USY, and then grows the USY shell layer with a mesoporous structure by means of a hydrothermal reaction with the help of a structure directing agent (a template agent) and taking the seeds as the core. The catalyst carbon deposition amount is reduced, the co-pyrolysis light oil content is improved, and the heavy oil content is reduced.

Description

Technical Field

[0001] This invention relates to the field of catalyst technology, specifically to a Ni / Ce / Zr-@USY co-pyrolysis catalyst for coal and waste plastics and its preparation method. Background Technology

[0002] Co-pyrolysis technology of coal and waste plastics has a synergistic effect of increasing oil and reducing water. While treating waste, it also improves the yield and quality of tar. This process has the characteristics of both raw material economy and high added value of products, and has dual potential in terms of economic and environmental benefits, which is in line with the policy orientation of low-carbon circular development.

[0003] Coal has a low H / C ratio (0.5–1.1), and the tar produced by direct pyrolysis is rich in high-boiling-point components with boiling points above 360℃, accounting for 50%–60%, resulting in limited yields of light, high-value-added products. In contrast, waste plastics have a significantly higher H / C ratio (1.5–2.0), and their pyrolysis alone more easily yields light tar. However, this technology is still underdeveloped and constrained by limitations such as an imperfect raw material collection system, small processing scale, and geographical concentration. Introducing waste plastics as a hydrogen-rich component into the coal pyrolysis process can utilize its hydrogen-donating effect to achieve a synergistic effect of "increasing oil and reducing water," effectively improving tar yield and quality while realizing waste resource utilization. However, the tar products obtained by existing co-pyrolysis technologies still contain a considerable proportion of heavy components, and the means to control product distribution are limited, with the selectivity of target products needing improvement.

[0004] Currently available catalysts (such as petroleum hydrocracking catalysts) typically require high-temperature and high-pressure reaction conditions and are mainly designed for petroleum fractions with relatively homogeneous compositions. Co-pyrolysis of coal and waste plastics usually takes place under milder conditions with complex feedstock compositions, especially coal, which contains a large number of complex macromolecular structures. Existing commercial petroleum catalytic cracking (FCC) catalysts lack the ability to break bonds in these macromolecules; while some core-shell catalysts reported in the literature exhibit significant mass transfer limitations at the core-shell interface, leading to rapid deactivation due to carbon deposition in actual reactions, thus restricting their application in this complex system. Summary of the Invention

[0005] To address the aforementioned technical problems, the first objective of this invention is to provide a method for preparing a Ni / Ce / Zr-@USY co-pyrolysis catalyst for coal and waste plastics. The second objective is to provide the Ni / Ce / Zr-@USY co-pyrolysis catalyst for coal and waste plastics prepared by this method. This reduces carbon deposition on the catalyst, increases the content of light oil from co-pyrolysis, and reduces the content of heavy oil.

[0006] To achieve the first objective mentioned above, the present invention provides the following technical solution: a method for preparing a Ni / Ce / Zr-@USY co-pyrolysis catalyst for coal and waste plastics, characterized by preparation according to the following steps:

[0007] Step (1) Pretreatment and surface modification of microporous USY

[0008] (1) Calcination: USY powder is calcined in a muffle furnace at 550-600℃ to remove organic matter and moisture that may be adsorbed in its pores;

[0009] (2) Surface charge modification: The activated USY was dispersed in a dilute NaOH solution, stirred at 60-65℃, then centrifuged, washed with deionized water until neutral, and dried to obtain dry USY powder;

[0010] Step (II) Surface seeding of USY

[0011] (1) Mix the alkali source, water and sodium aluminate and stir until completely dissolved. Add tetraethyl orthosilicate dropwise to the above solution under ice-water bath and stirring. After the addition is complete, remove the ice bath and continue stirring at room temperature to obtain a clear or translucent colloidal solution rich in nano-crystal seeds.

[0012] (2) Disperse the pretreated and dried USY powder in deionized water to form a uniform slurry;

[0013] (3) While stirring at 25~60℃, slowly add the colloidal solution dropwise into the USY slurry;

[0014] (4) Stirring allows the seed crystals to be fully and firmly adsorbed onto the surface of the USY nucleus through electrostatic attraction. Centrifugation, washing, and drying are then performed to obtain the “seedled” USY nucleus.

[0015] Step (3) Synthesis of precursor gel for mesoporous USY shell

[0016] (1) Template solution: Dissolve the template agent in a mixed solvent of deionized water and ethanol, and stir in a water bath at 20~60℃ until clear.

[0017] (2) Add the obtained “seedled” USY core to the above template agent solution, sonicate and stir to disperse it evenly;

[0018] (3) Add silicon and aluminum sources: While stirring, slowly add tetraethyl orthosilicate dropwise, continue stirring until the tetraethyl orthosilicate is completely hydrolyzed, then add the aluminum source, ensuring that the aluminum source is fully dispersed and mixed.

[0019] (4) Adjust the pH value: Add an alkaline source solution to adjust the pH value of the mixed gel to 10-11.5;

[0020] (5) Aging: The reaction gel is continuously stirred at room temperature for 6-12 hours to allow the silicon-aluminum species, template micro-clusters and seed crystal surfaces to be fully pre-organized and assembled;

[0021] Step (IV) Hydrothermal Crystallization and Shell Growth

[0022] The aged gel was transferred to a stainless steel high-pressure reactor lined with polytetrafluoroethylene, sealed, and placed in an oven for crystallization at a temperature of 80-160°C.

[0023] Step (5) Post-processing and activation

[0024] (1) Cooling and washing: After crystallization, the reactor is naturally cooled to room temperature. The product is taken out and repeatedly washed with deionized water and ethanol. It is then centrifuged until no bromide ions are detected in the supernatant using silver nitrate solution. The washed filter cake is then dried.

[0025] (2) Template agent removal: The dried powder is calcined in a muffle furnace with a programmed temperature increase of 1-5°C / min to 450-580°C, and held at this temperature for 3-6 hours to obtain USY molecular sieve;

[0026] Step (VI) Synthesis of Ni / Ce / Zr-@USY with core-shell structure by ethanol impregnation method

[0027] (1) Impregnation of Ce and Zr: Prepare a mixed ethanol solution of cerium nitrate and zirconium nitrate, place the USY molecular sieve and the mixed solution together in a sealed bag and knead until uniform, then place the sealed bag open in a fume hood to dry, and then calcine in a muffle furnace at 450~600℃ for 1~5h to obtain Ce / Zr-@USY;

[0028] (2) Impregnation of Ni: Add Ce / Zr-@USY to nickel nitrate ethanol solution, knead in a sealed bag until uniform, then place the sealed bag open in a fume hood to dry, calcine in a muffle furnace at 450~600℃ for 1~5h, and reduce in a hydrogen atmosphere at 500-600℃ for 1~3h. The resulting catalyst is core-shell Ni / Ce / Zr-@USY with hierarchical pore structure.

[0029] In step (1), the USY powder is calcined for 5-6 hours and stirred for 2-3 hours.

[0030] The alkali source is at least one of tetramethylammonium hydroxide, tetrapropylammonium hydroxide, or NaOH. The ratio of alkali source, water, sodium aluminate, and USY powder is 6-20g alkali source: 100ml water: 2-10g sodium aluminate: 1g USY powder, and the amount of tetraethyl orthosilicate added is 2.5-5.5g / 1g USY powder.

[0031] In step (iii) (1), the volume ratio of deionized water to ethanol in the mixed solvent of deionized water and ethanol is 4:1, and the template agent is hexadecyltrimethylammonium bromide or poloxamer. 0.5-2.0g of the template agent is added to 25mL of the mixed solvent of deionized water and ethanol.

[0032] In step (iii) (3), the aluminum source is at least one of aluminum isopropoxide, aluminum sulfate or boehmite, and the mass ratio of aluminum source to tetraethyl orthosilicate and USY powder is 0.05~20g aluminum source: 0.1~10g tetraethyl orthosilicate: 1g USY powder.

[0033] In step (four), the crystallization time is 45-50 hours.

[0034] In step (vi), the mass ratio of cerium nitrate, zirconium nitrate, and nickel nitrate is 0.2~8.0g; 1.0~10.0g: 0.5-7.0g.

[0035] The method for preparing the coal and waste plastic co-pyrolysis catalyst Ni / Ce / Zr-@USY yields the coal and waste plastic co-pyrolysis catalyst Ni / Ce / Zr-@USY.

[0036] The core of the method of this invention is to first "graft" a layer of seed crystals that can induce the growth of mesoporous USY onto the surface of commercial USY, and then, through a hydrothermal reaction, with the help of a structure guiding agent (templating agent), grow a USY shell with a mesoporous structure with these seed crystals as the core.

[0037] The cracking of polycyclic aromatic hydrocarbons (PAHs) requires strong acidic sites to activate C–C bonds. The resulting small-molecule free radicals rapidly combine and stabilize, preventing repolymerization to form higher-ring-number aromatics or carbon deposits, thus reducing the impact of carbon deposits on catalyst activity. This invention uses commercially available microporous USY as the core and deposited mesoporous USY as the shell, with added active metals Ni, Ce, and Zr. The mesoporous shell primarily functions as a pre-cracking and transport layer, pre-cracking large molecules on the surface. Even if there is a small amount of carbon deposit in the channels, it mainly occurs within the mesoporous channels and does not block key active centers. Furthermore, the carbon deposits within the mesopores are more easily removed by coking. Products generated in the catalyst core layer can also be rapidly transferred to the mesopores, avoiding over-reaction. This increases the content of low-carbon aromatics (benzene, toluene, xylene, styrene, ethylbenzene, naphthalene, abbreviated as BTESXN) in the co-pyrolysis tar product.

[0038] This technology aims to address a key catalytic bottleneck in the co-pyrolysis of coal and waste plastics. The large hydrocarbon molecules produced during pyrolysis struggle to penetrate traditional microporous catalysts, leading to low catalyst surface utilization, easy carbon buildup and deactivation, and poor diffusion efficiency of complex reactants, thus limiting product selectivity and process economy. The developed mesoporous-microporous USY core-shell catalyst features an outer mesoporous shell providing a rapid transport channel for large waste plastic molecules, while the inner microporous core ensures shape-selective catalysis and strong acidity. Fragments detached from the shell (mesoporous region) diffuse along the mesopores into the sphere, undergoing continuous β-cracks, isomerization, and dehydrogenation reactions at the mesoporous active sites to generate medium-carbon hydrocarbon intermediates. In the core region, smaller molecules continue to enter the innermost microporous region, undergoing deep cracking and aromatization at the high-density, strongly acidic active sites, ultimately generating lightweight small-molecule products. This hierarchical pore structure significantly alleviates diffusion limitations, improves the accessibility of large molecules, and effectively delays carbon buildup. Ni, as the main active center, is responsible for dehydrogenation aromatization and hydrogenolysis. Ce and Zr form a stable Ce-Zr solid solution, which acts as a multifunctional promoter. Through its oxygen storage capacity, it oxidizes and removes carbon deposits around Ni, preventing Ni from sintering and becoming deactivated by carbon buildup. This synergistically optimizes reaction pathways such as cracking and isomerization in a single catalyst. This catalyst requires no large-scale modification of existing fluidized bed or fixed bed reactors; it can be used directly as a replacement. Using a post-synthetic modification of commercial USY reduces raw material costs by approximately 60% compared to fully synthetic mesoporous molecular sieves. By inhibiting excessive cracking, higher yields of light fuel oil and chemical feedstocks can be obtained. This catalyst can directly improve the feedstock adaptability, light oil yield, and operating cycle of existing co-pyrolysis units, demonstrating significant potential for industrial application. Its successful development will provide key material support for the efficient co-conversion of coal and waste plastics, possessing significant economic and environmental value. Attached Figure Description

[0039] Figure 1 It is a raw material for bituminous coal.

[0040] Figure 2 It is a raw material from waste plastics.

[0041] Figure 3 Images of the various powders prepared: (a) USY, (b) @USY, (c) Ni-@USY, (d) Ni / Ce / Zr-@USY.

[0042] Figure 4 Comparison of tar products from co-pyrolysis of coal and waste plastics using different catalysts.

[0043] Figure 5 These are low-carbon aromatic hydrocarbons obtained by co-pyrolysis catalyzed by different catalysts.

[0044] Figure 6This is a schematic diagram of a two-stage fixed-bed catalytic waste plastic pyrolysis reactor.

[0045] Figure 7 The crystal composition of Ni / Ce / Zr-@USY is determined by testing. Detailed Implementation

[0046] The present invention will now be further described with reference to the accompanying drawings and embodiments.

[0047] Example 1

[0048] A hierarchical porous core-shell structured Ni / Ce / Zr-@USY catalyst, the preparation steps of which are as follows:

[0049] (1) Take 1g of commercial microporous USY powder and calcine it in a muffle furnace at 550°C for 5 hours to remove the organic matter and moisture adsorbed in the pores; disperse the calcined USY (silicon-aluminum ratio 5~80) in a dilute NaOH solution (concentration 1M), stir at 60°C for 2 hours, centrifuge, wash with deionized water until neutral, and dry at 110°C overnight to obtain activated and modified USY-cores.

[0050] (2) USY surface seeding treatment: ① Preparation of nano-USY seed colloidal solution: Weigh 6g tetramethylammonium hydroxide (TMAOH) and 10g sodium aluminate, add them to a beaker containing 100mL deionized water, and stir until completely dissolved. Place the beaker in an ice-water bath, and under vigorous stirring, slowly add tetraethyl orthosilicate (TEOS) (4.6g). After the addition is complete, remove the ice bath and continue stirring at room temperature for 24 hours to obtain a clear nano-seed colloidal solution. ② Seed adsorption: Disperse the USY-cores obtained in step (1) in 30mL of deionized water, sonicate to form a uniform slurry, and slowly add the seed colloidal solution to the slurry under stirring at 25~80℃. Continue stirring for several hours to allow the seed crystals to be adsorbed onto the USY core surface by electrostatic attraction. Then, centrifuge to separate the solid, wash with deionized water, and dry at 100℃ for 4 hours to obtain "seedled USY core".

[0051] (3) Synthesis of mesoporous USY shell precursor gel: ① Preparation of template solution: Weigh 1.0g cetyltrimethylammonium bromide (CTAB), add it to a mixed solvent of 20ml deionized water and 5ml anhydrous ethanol, and stir in a water bath at 20~60℃ until clear; ② Disperse seeded USY cores: Add the “seeded USY cores” obtained in step (2) to the template solution and stir evenly with ultrasonication; ③ Add silicon-aluminum source: Under continuous stirring, slowly add 0.1g TEOS and stir until TEOS is completely hydrolyzed, then add 20g aluminum isopropoxide; ④ Adjust pH and aging: Slowly add TMAOH solution to adjust the pH of the system to 10~11.5, stir at room temperature for 8 hours to age, and obtain mesoporous USY shell precursor gel.

[0052] (4) Hydrothermal crystallization to achieve shell growth: The precursor gel after aging in step (3) is transferred to a stainless steel high-pressure reactor lined with polytetrafluoroethylene, sealed and placed in an oven for constant temperature crystallization at 120°C for 48 hours.

[0053] (5) Post-processing and carrier activation: ① Cooling and washing: Cool the reactor to room temperature naturally, take out the product, and wash it with deionized water and anhydrous ethanol alternately by centrifugation 5 times (5 minutes each time) until no white precipitate is found when silver nitrate solution is added to the supernatant. This indicates that there are no bromide ions in the supernatant, ensuring that CTAB is completely removed; ② Drying and calcination: Put the washed filter cake into a muffle furnace and calcine it at 1-5°C / min to 500°C for 4 hours to obtain a pure core-shell structure USY molecular sieve carrier.

[0054] (6) Ethanol impregnation of Ce and Zr active components: Weigh 4g of cerium nitrate and 6g of zirconium nitrate, dissolve them together in 50mL of anhydrous ethanol to prepare a homogeneous mixed solution. Add the USY molecular sieve carrier obtained in step (5) to the solution, transfer it to a sealed bag and knead it repeatedly for 10 minutes until it is evenly mixed, then place it in a fume hood to dry for 10 hours. Then place the dried material in a muffle furnace and calcine it at 550℃ for 3 hours to obtain the Ce / Zr-@USY intermediate.

[0055] (7) Ethanol impregnation of supported Ni and catalyst molding: Weigh 3g of nickel nitrate and dissolve it in 50mL of anhydrous ethanol to prepare an impregnation solution. Add the Ce / Zr-@USY intermediate obtained in step (6) to the solution and knead it in a sealed bag until it is fully impregnated and free of lumps. Place the sealed bag open in a fume hood to dry for 10 hours. After the ethanol has completely evaporated, place it in a muffle furnace and heat it to 550℃. Calcinate it at a constant temperature for 4 hours and then calcine it in a hydrogen atmosphere at 550℃ for 3 hours to convert the nickel nitrate into the active Ni component. Finally, a core-shell Ni / Ce / Zr-@USY waste plastic pyrolysis catalyst with a hierarchical pore structure is obtained.

[0056] (8) Take 0.5g of waste plastic (insulation boards, packaging materials, electrical appliance shells, toys, stationery, disposable tableware, transparent shells, experimental instruments, scraps of rigid packaging materials, etc., found in a certain waste treatment plant), 4.5g of bituminous coal and 1g of core-shell Ni / Ce / Zr-@USY catalyst respectively and place them in the pyrolysis section and catalytic section of a two-stage fixed-bed reactor for catalytic pyrolysis experiments. The temperatures of the pyrolysis section and catalytic section are 550℃ and 500℃, respectively. After pyrolysis for 30min, collect the bottom liquid phase product pyrolysis oil, extract and separate the light oil and heavy oil and weigh them respectively.

[0057] Example 2

[0058] Same as Example 1, except for step (8), take 0.5g of waste plastic (such as insulation boards, packaging materials, electrical appliance shells, toys, stationery, disposable tableware, transparent shells, experimental instruments, and scraps of rigid packaging materials found in a waste treatment plant), 4.5g of bituminous coal and 1g of Ni-@USY catalyst respectively and place them in the pyrolysis section and catalytic section sleeve of a two-stage fixed-bed reactor for catalytic pyrolysis experiment. The temperatures of the pyrolysis section and catalytic section are 550℃ and 500℃ respectively. After pyrolysis for 30min, collect the bottom liquid phase product pyrolysis oil, extract and separate the light oil and heavy oil and weigh them respectively.

[0059] Example 3

[0060] Same as Example 1, except for step (8), take 0.5g of waste plastic (take insulation boards, packaging materials, electrical appliance shells, toys, stationery, disposable tableware, transparent shells, test instruments, scraps of rigid packaging materials, etc. that exist in a certain waste treatment plant), 4.5g of bituminous coal and 1g of @USY respectively and place them in the pyrolysis section and catalytic section sleeve of a two-stage fixed bed reactor for catalytic pyrolysis experiment. The temperature of the pyrolysis section and the catalytic section are 550℃ and 500℃ respectively. After pyrolysis for 30min, collect the bottom liquid phase product pyrolysis oil, extract and separate the light oil and heavy oil and weigh them respectively.

[0061] Example 4

[0062] Same as Example 1, except for step (8), take 0.5g of waste plastic (take insulation boards, packaging materials, electrical appliance shells, toys, stationery, disposable tableware, transparent shells, test instruments, scraps of rigid packaging materials, etc. that exist in a certain waste treatment plant), 4.5g of bituminous coal and 1g of USY respectively and place them in the pyrolysis section and catalytic section sleeve of a two-stage fixed bed reactor for catalytic pyrolysis experiment. The temperature of the pyrolysis section and the catalytic section are 550℃ and 500℃ respectively. After pyrolysis for 30min, collect the bottom liquid phase product pyrolysis oil, extract and separate the light oil and heavy oil and weigh them respectively.

[0063] Example 5

[0064] Similar to Example 1, except that in step (8) no catalyst is added. Take 0.5g of waste plastic (insulation boards, packaging materials, electrical appliance shells, toys, stationery, disposable tableware, transparent shells, experimental instruments, scraps of rigid packaging materials, etc. that exist in a certain waste treatment plant) and 4.5g of bituminous coal and place them in the pyrolysis section and catalytic section sleeve of a two-stage fixed bed reactor for catalytic pyrolysis experiment. The temperatures of the pyrolysis section and catalytic section are 550℃ and 500℃, respectively. After pyrolysis for 30min, collect the bottom liquid phase product pyrolysis oil, extract and separate the light oil and heavy oil and weigh them respectively.

[0065] The two-stage fixed-bed reactor used in the experiment is a current technology, such as... Figure 6 As shown, the reactor includes an air inlet 1, a quartz tube reactor 2, a pyrolysis sleeve 3, a support tube 4, a catalytic sleeve 5, an ice-salt bath 6, a gas bag 7, a temperature controller 8, and an insulation layer 9. The pyrolysis atmosphere N2 enters the reactor through the air inlet. The two temperature controllers 8 control the pyrolysis temperature and the catalytic temperature (3 and 5) respectively. The support tube 4 provides space for the diffusion of pyrolysis volatiles and facilitates the separation of waste plastics and catalysts. The catalytic pyrolysis device collects liquid phase products through the external ice-salt bath 6, while non-condensable gases are collected by the gas bag 7. The external insulation layer 9 of the reactor prevents heat loss through heat exchange with the environment.

[0066] Table 1 Catalyst Description

[0067]

[0068] Table 2 compares and analyzes the performance of USY molecular sieve composite materials.

[0069]

[0070] As can be seen from the data in Table 2, after coating with a shell, the mesopore volume and specific surface area increased significantly, while the amount of carbon deposits on the catalyst decreased significantly.

[0071] Table 3 Catalytic effects of Ni / Ce / Zr-@USY on different types of waste plastics

[0072]

[0073] The experimental results of Examples 1-5 are as follows: Figure 4 As shown, from Figure 4 As can be seen from the data, the Ni / Ce / Zr-@USY method using the present invention has the lowest heavy oil content.

[0074] In Table 3, under the columns for insulation boards, packaging materials, and appliance casings, the mass ratio of insulation boards to packaging materials to appliance casings is 4:3:3; the raw materials for the reaction system are 90% bituminous coal + toys, stationery, and disposable tableware (10%), and the mass ratio of reactants to catalyst is 5:1. Under the columns for toys, stationery, and disposable tableware, the mass ratio of toys to stationery to disposable tableware is 4:3:3; the raw materials for the reaction system are 90% bituminous coal + toys, stationery, and disposable tableware (10%), and the mass ratio of reactants to catalyst is 5:1. Under the columns for transparent casings, testing instruments, and rigid packaging materials, the mass ratio of transparent casings to testing instruments to rigid packaging materials is 4:3:3; the raw materials for the reaction system are 90% bituminous coal + 10% transparent casings, testing instruments, and rigid packaging materials, and the mass ratio of reactants to catalyst is 5:1.

[0075] Example 6

[0076] A hierarchical porous core-shell structured Ni / Ce / Zr-@USY catalyst, the preparation steps of which are as follows:

[0077] (1) Take 1g of commercial microporous USY powder and calcine it in a muffle furnace at 600℃ for 6 hours to remove the organic matter and moisture adsorbed in the pores; disperse the calcined USY (silicon-aluminum ratio 5~80) in a dilute NaOH solution (concentration 1M), stir at 60-65℃ for 3 hours, centrifuge, wash with deionized water until neutral, and dry at 110℃ overnight to obtain activated and modified USY-cores.

[0078] (2) USY surface seeding treatment: ① Preparation of nano-USY seed colloidal solution: Weigh 20g tetrapropylammonium hydroxide and 2g sodium aluminate, add them to a beaker containing 100mL deionized water, and stir until completely dissolved. Place the beaker in an ice-water bath, and slowly add TEOS (2.5g) dropwise while stirring vigorously. After the addition is complete, remove the ice bath and continue stirring at room temperature for 24 hours to obtain a clear nano-seed colloidal solution. ② Seed adsorption: Disperse the USY-cores obtained in step (1) in 20~30mL of deionized water, sonicate to form a uniform slurry, and slowly drop the seed colloidal solution into the slurry while stirring at 25~80℃. Continue stirring for several hours to allow the seed crystals to be adsorbed onto the USY core surface by electrostatic attraction. Then centrifuge to separate the solid, wash with deionized water, and dry at 100℃ for 4 hours to obtain "seedled USY core".

[0079] (3) Synthesis of mesoporous USY shell precursor gel: ① Preparation of template solution: Weigh 2.0g of poloxamer P123, add it to a mixed solvent of 20ml deionized water and 5ml anhydrous ethanol, and stir in a water bath at 20~60℃ until clear; ② Disperse seeded USY cores: Add the “seeded USY cores” obtained in step (2) to the template solution and stir evenly with ultrasound; ③ Add silicon-aluminum source: Under continuous stirring, slowly add 10g of TEOS and stir until TEOS is completely hydrolyzed, then add 0.05g of aluminum sulfate; ④ Adjust pH and aging: Slowly add TMAOH solution to adjust the pH of the system to 10~11.5, stir at room temperature for 12 hours to age, and obtain mesoporous USY shell precursor gel.

[0080] (4) Hydrothermal crystallization to achieve shell growth: The precursor gel after aging in step (3) is transferred to a stainless steel high-pressure reactor lined with polytetrafluoroethylene, sealed and placed in an oven for constant temperature crystallization at 160°C for 45 hours.

[0081] (5) Post-processing and carrier activation: ① Cooling and washing: Cool the reactor to room temperature naturally, take out the product, and wash it with deionized water and anhydrous ethanol alternately by centrifugation 5 times (5 minutes each time) until no white precipitate is found when silver nitrate solution is added to the supernatant. This indicates that there are no bromide ions in the supernatant, ensuring that CTAB is completely removed; ② Drying and calcination: Put the washed filter cake into a muffle furnace and calcine it at 1-5°C / min to 580°C for 3 hours to obtain a pure core-shell structure USY molecular sieve carrier.

[0082] (6) Ethanol impregnation of Ce and Zr active components: Weigh 0.2 g of cerium nitrate and 10 g of zirconium nitrate, dissolve them together in 50 mL of anhydrous ethanol to prepare a homogeneous mixed solution. Add the USY molecular sieve carrier obtained in step (5) to the solution, transfer it to a sealed bag and knead it repeatedly for 10 minutes until it is evenly mixed, then place it in a fume hood to dry for 10 hours. Then place the dried material in a muffle furnace and calcine it at 450 °C for 5 hours to obtain the Ce / Zr-@USY intermediate.

[0083] (7) Ethanol impregnation of supported Ni and catalyst molding: Weigh 7g of nickel nitrate and dissolve it in 50mL of anhydrous ethanol to prepare an impregnation solution. Add the Ce / Zr-@USY intermediate obtained in step (6) to the solution and knead it in a sealed bag until it is fully impregnated and free of lumps. Place the sealed bag open in a fume hood to dry for 10 hours. After the ethanol has completely evaporated, place it in a muffle furnace and heat it to 450℃. Calcinate it at a constant temperature for 5 hours and then calcine it at 500℃ in a hydrogen atmosphere for 3 hours to convert the nickel nitrate into the active Ni component. Finally, a core-shell Ni / Ce / Zr-@USY waste plastic pyrolysis catalyst with a hierarchical pore structure is obtained.

[0084] (8) Take 0.5g of waste plastic (insulation boards, packaging materials, electrical appliance casings, toys, stationery, disposable tableware, transparent casings, experimental instruments, scraps of rigid packaging materials, etc., found in a certain waste treatment plant, as in Example 1), 4.5g of bituminous coal, and 1g of core-shell Ni / Ce / Zr-@USY catalyst, respectively, and place them in the pyrolysis section and catalytic section sleeve of a two-stage fixed-bed reactor for catalytic pyrolysis experiments. The temperatures of the pyrolysis section and catalytic section are 550℃ and 500℃, respectively. After pyrolysis for 30 minutes, collect the bottom liquid phase product pyrolysis oil, extract and separate the light oil and heavy oil, and weigh them separately. The light oil is 95.19%, and the heavy oil is 4.81%.

[0085] Example 7

[0086] A hierarchical porous core-shell structured Ni / Ce / Zr-@USY catalyst, the preparation steps of which are as follows:

[0087] (1) Take 1g of commercial microporous USY powder and calcine it in a muffle furnace at 550℃ for 6 hours to remove the organic matter and moisture adsorbed in the pores; disperse the calcined USY (silicon-aluminum ratio 5~80) in a dilute NaOH solution (concentration 1M), stir at 60℃ for 3 hours, centrifuge, wash with deionized water until neutral, and dry at 110℃ overnight to obtain activated and modified USY-cores.

[0088] (2) USY surface seeding treatment: ① Preparation of nano-USY seed colloidal solution: Weigh 10g TMAOH and 5g sodium aluminate, add them to a beaker containing 100mL deionized water, and stir until completely dissolved. Place the beaker in an ice-water bath, and slowly add 5.5g TEOS dropwise while stirring vigorously. After the addition is complete, remove the ice bath and continue stirring at room temperature for 24 hours to obtain a clear nano-seed colloidal solution. ② Seed adsorption: Disperse the USY-cores obtained in step (1) in 20~30mL of deionized water, sonicate to form a uniform slurry, and slowly drop the seed colloidal solution into the slurry while stirring at 25~80℃. Continue stirring for several hours to allow the seed crystals to be adsorbed onto the USY core surface by electrostatic attraction. Then, centrifuge to separate the solid, wash with deionized water, and dry at 100℃ for 4 hours to obtain "seedled USY core".

[0089] (3) Synthesis of mesoporous USY shell precursor gel: ① Preparation of template solution: Weigh 1.0g cetyltrimethylammonium bromide (CTAB), add it to a mixed solvent of 20ml deionized water and 5ml anhydrous ethanol, and stir in a water bath at 20~60℃ until clear; ② Disperse seeded USY cores: Add the “seeded USY cores” obtained in step (2) to the template solution and stir evenly with ultrasonication; ③ Add silicon-aluminum source: Under continuous stirring, slowly add 2g TEOS and stir until TEOS is completely hydrolyzed, then add 10g pseudoboehmite; ④ Adjust pH and aging: Slowly add sodium hydroxide solution (1M) to adjust the pH of the system to 10~11.5, stir at room temperature for 6 hours to age, and obtain mesoporous USY shell precursor gel.

[0090] (4) Hydrothermal crystallization to achieve shell growth: The precursor gel after aging in step (3) is transferred to a stainless steel high-pressure reactor lined with polytetrafluoroethylene, sealed and placed in an oven for constant temperature crystallization at 80°C for 50 hours.

[0091] (5) Post-processing and carrier activation: ① Cooling and washing: Cool the reactor to room temperature naturally, take out the product, and wash it 5 times with deionized water and anhydrous ethanol (5 minutes each time) until no white precipitate is added to the supernatant. Then test the supernatant for bromide ions to ensure that CTAB is completely removed; ② Drying and calcination: Put the washed filter cake into a muffle furnace and calcine it at 1-5°C / min to 450°C for 6 hours to obtain a pure core-shell structure USY molecular sieve carrier.

[0092] (6) Ethanol impregnation of Ce and Zr active components: Weigh 8.0 g of cerium nitrate and 1 g of zirconium nitrate, dissolve them together in 50 mL of anhydrous ethanol to prepare a homogeneous mixed solution. Add the USY molecular sieve carrier obtained in step (5) to the solution, transfer it to a sealed bag and knead it repeatedly for 10 minutes until it is evenly mixed, then place it in a fume hood to dry for 10 hours. Then place the dried material in a muffle furnace and calcine it at 600 °C for 1 hour to obtain the Ce / Zr-@USY intermediate.

[0093] (7) Ethanol impregnation of Ni and catalyst molding: Weigh 0.5g of nickel nitrate and dissolve it in 50mL of anhydrous ethanol to prepare an impregnation solution. Add the Ce / Zr-@USY intermediate obtained in step (6) to the solution and knead it in a sealed bag until it is fully impregnated and free of lumps. Place the sealed bag open in a fume hood to dry for 10 hours. After the ethanol has completely evaporated, place it in a muffle furnace and heat it to 600℃. Calcinate it at a constant temperature for 1 hour, and then calcine it at 600℃ in a hydrogen atmosphere for 1 hour to convert the nickel nitrate into the active Ni component. Finally, a core-shell Ni / Ce / Zr-@USY waste plastic pyrolysis catalyst with a hierarchical pore structure is obtained.

[0094] (8) Take 0.5g of waste plastic (insulation boards, packaging materials, electrical appliance casings, toys, stationery, disposable tableware, transparent casings, experimental instruments, scraps of rigid packaging materials, etc., found in a certain waste treatment plant, as in Example 1), 4.5g of bituminous coal, and 1g of core-shell Ni / Ce / Zr-@USY catalyst, respectively, and place them in the pyrolysis section and catalytic section sleeves of a two-stage fixed-bed reactor for catalytic pyrolysis experiments. The temperatures of the pyrolysis section and catalytic section are 550℃ and 500℃, respectively. After pyrolysis for 30 minutes, collect the bottom liquid phase product pyrolysis oil, extract and separate the light oil and heavy oil, and weigh them separately. The light oil is 95.74%, and the heavy oil is 4.26%.

[0095] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a Ni / Ce / Zr-@USY co-pyrolysis catalyst for coal and waste plastics, characterized in that, Prepare according to the following steps: Step (1) Pretreatment and surface modification of microporous USY (1) Calcination: USY powder is calcined in a muffle furnace at 550-600℃ to remove organic matter and moisture that may be adsorbed in its pores; (2) Surface charge modification: The activated USY was dispersed in a dilute NaOH solution, stirred at 60-65℃, then centrifuged, washed with deionized water until neutral, and dried to obtain dry USY powder; Step (II) Surface seeding of USY (1) Mix the alkali source, water and sodium aluminate and stir until completely dissolved. Add tetraethyl orthosilicate dropwise to the above solution under ice-water bath and stirring. After the addition is complete, remove the ice bath and continue stirring at room temperature to obtain a clear or translucent colloidal solution rich in nano-crystal seeds. (2) Disperse the pretreated and dried USY powder in deionized water to form a uniform slurry; (3) While stirring at 25~60℃, slowly add the colloidal solution dropwise into the USY slurry; (4) Stirring allows the seed crystals to be fully and firmly adsorbed onto the surface of the USY nucleus through electrostatic attraction. Centrifugation, washing, and drying are then performed to obtain the "seedled" USY nucleus. Step (3) Synthesis of precursor gel for mesoporous USY shell (1) Template solution: Dissolve the template agent in a mixed solvent of deionized water and ethanol, and stir in a water bath at 20~60℃ until clear; (2) Add the obtained "seedled" USY core to the above template agent solution, sonicate and stir to disperse it evenly; (3) Add silicon and aluminum sources: While stirring, slowly add tetraethyl orthosilicate dropwise, continue stirring until the tetraethyl orthosilicate is completely hydrolyzed, then add the aluminum source, ensuring that the aluminum source is fully dispersed and mixed. (4) Adjust the pH value: Add an alkaline source solution to adjust the pH value of the mixed gel to 10-11.5; (5) Aging: The reaction gel is continuously stirred at room temperature for 6-12 hours to allow the silicon-aluminum species, template micro-clusters and seed crystal surfaces to be fully pre-organized and assembled; Step (IV) Hydrothermal Crystallization and Shell Growth The aged gel was transferred to a stainless steel high-pressure reactor lined with polytetrafluoroethylene, sealed, and placed in an oven for crystallization at a temperature of 80-160°C. Step (5) Post-processing and activation (1) Cooling and washing: After crystallization, the reactor is naturally cooled to room temperature. The product is taken out and repeatedly washed with deionized water and ethanol. It is then centrifuged until no bromide ions are detected in the supernatant using silver nitrate solution. The washed filter cake is then dried. (2) Template agent removal: The dried powder is calcined in a muffle furnace with a programmed temperature increase of 1-5°C / min to 450-580°C, and held at this temperature for 3-6 hours to obtain USY molecular sieve; Step (VI) Synthesis of Ni / Ce / Zr-@USY with core-shell structure by ethanol impregnation method (1) Impregnation of Ce and Zr: Prepare a mixed ethanol solution of cerium nitrate and zirconium nitrate, place the USY molecular sieve and the mixed solution together in a sealed bag and knead until uniform, then place the sealed bag open in a fume hood to dry, and then calcine in a muffle furnace at 450~600℃ for 1~5h to obtain Ce / Zr-@USY; (2) Impregnation of Ni: Add Ce / Zr-@USY to nickel nitrate ethanol solution, knead in a sealed bag until uniform, then place the sealed bag open in a fume hood to dry, calcine in a muffle furnace at 450~600℃ for 1~5h, and reduce in a hydrogen atmosphere at 500-600℃ for 1~3h. The resulting catalyst is core-shell Ni / Ce / Zr-@USY with hierarchical pore structure.

2. The preparation method of the Ni / Ce / Zr-@USY co-pyrolysis catalyst for coal and waste plastics according to claim 1, characterized in that: In step (1), the USY powder is calcined for 5-6 hours and stirred for 2-3 hours.

3. The preparation method of the Ni / Ce / Zr-@USY co-pyrolysis catalyst for coal and waste plastics according to claim 1 or 2, characterized in that: The alkali source is at least one of tetramethylammonium hydroxide, tetrapropylammonium hydroxide, or NaOH. The ratio of alkali source, water, sodium aluminate, and USY powder is 6-20g alkali source: 100ml water: 2-10g sodium aluminate: 1g USY powder. The amount of tetraethyl orthosilicate added is 2.5-5.5g / 1g USY powder.

4. The preparation method of the Ni / Ce / Zr-@USY co-pyrolysis catalyst for coal and waste plastics according to claim 3, characterized in that: In step (iii) (1), the volume ratio of deionized water to ethanol in the mixed solvent of deionized water and ethanol is 4:

1. The template agent is hexadecyltrimethylammonium bromide or poloxamer. 0.5-2g of template agent is added to 25mL of the mixed solvent of deionized water and ethanol.

5. The preparation method of the Ni / Ce / Zr-@USY co-pyrolysis catalyst for coal and waste plastics according to claim 3, characterized in that: In step (iii) (3), the aluminum source is at least one of aluminum isopropoxide, aluminum sulfate or boehmite, and the mass ratio of aluminum source to tetraethyl orthosilicate and USY powder is 0.05~20g aluminum source: 0.1~10g tetraethyl orthosilicate: 1g USY powder.

6. The preparation method of the Ni / Ce / Zr-@USY co-pyrolysis catalyst for coal and waste plastics according to claim 5, characterized in that: In step (four), the crystallization time is 45-50 hours.

7. The preparation method of the Ni / Ce / Zr-@USY co-pyrolysis catalyst for coal and waste plastics according to claim 6, characterized in that: In step (vi), the mass ratio of cerium nitrate, zirconium nitrate, and nickel nitrate is 0.2~8.0g; 1.0~10.0g: 0.5-7.0g.

8. A coal and waste plastic co-pyrolysis catalyst Ni / Ce / Zr-@USY prepared by the method according to any one of claims 1-7.

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