Method for producing light aromatic hydrocarbons by co-pyrolysis of biomass and waste plastics

Abstract

The present disclosure provides a method for co-pyrolysis of biomass and waste plastics to produce light aromatics, which comprises: subjecting a mixture of biomass raw material and waste plastics to a pyrolysis reaction under a nitrogen atmosphere to produce a pyrolysis product; contacting the pyrolysis product with a catalyst to produce a conversion product; and subjecting the conversion product to a condensation treatment to obtain a liquid product rich in light aromatics, wherein the catalyst is an HZSM-5 catalyst loaded with Ni and Fe. By utilizing the synergistic catalysis of Ni and Fe bimetal, the deoxygenation and aromatization reactions of the main components of biomass pyrolysis volatiles are simultaneously strengthened, and the polymerization, cyclization and aromatization reactions of the main components of waste plastic pyrolysis volatiles, i.e. olefins and alkanes, are simultaneously strengthened, thereby improving the yield of light aromatics in the co-catalytic pyrolysis process of biomass and waste plastics.

Description

Technical Field

[0001] This disclosure belongs to the field of biomass and waste plastic resource utilization technology, specifically relating to a method for producing light aromatic hydrocarbons by co-pyrolysis of biomass and waste plastics. Background Technology

[0002] my country produces approximately 3.5 billion tons of biomass resources annually and over 70 million tons of waste plastics annually. Developing technologies for the resource utilization of biomass and waste plastics is of great significance for achieving my country's "dual carbon" goals.

[0003] Light aromatic hydrocarbons such as benzene, toluene, xylene, and ethylbenzene are key raw materials for petrochemicals and organic synthesis. Currently, they are mainly extracted and prepared from fossil fuels. However, the reserves of fossil fuels are decreasing and their utilization process causes environmental pollution problems. Therefore, there is an urgent need to find sustainable and environmentally friendly alternative raw materials for aromatic hydrocarbon production.

[0004] Biomass, as the only renewable carbon-containing resource, can produce light aromatics through catalytic pyrolysis, making it an excellent alternative to fossil fuels. However, the hydrogen-poor and oxygen-rich nature of biomass results in low yields and selectivity of light aromatics during its catalytic pyrolysis process, and the catalyst is prone to carbon buildup and deactivation. Waste plastics are a high-quality hydrogen-rich resource that can provide a supplementary hydrogen source for the rapid catalytic pyrolysis process of biomass.

[0005] Currently, HZSM-5 catalysts are widely used in this field. However, the volatiles from the co-catalytic pyrolysis of biomass and waste plastics are complex, mainly composed of oxygen-containing compounds (phenols, furans, acids, aldehydes, ketones, etc.) and aliphatic hydrocarbons (olefins, alkanes, etc.). The acidic sites of HZSM-5 itself are difficult to efficiently catalyze the simultaneous and directional conversion of oxygen-containing compounds and aliphatic hydrocarbons. Therefore, existing co-catalytic pyrolysis methods for biomass and waste plastics still face the need to further improve the yield and selectivity of light aromatics, and to suppress catalyst coking and the formation of polycyclic aromatic hydrocarbons. Therefore, there is an urgent need to develop a method for the efficient production of light aromatics from the co-catalytic pyrolysis of biomass and waste plastics. Summary of the Invention

[0006] To overcome the shortcomings of the prior art, the present disclosure aims to provide a method for producing light aromatics through co-pyrolysis of biomass and waste plastics. This method employs a co-impregnation method to prepare a Ni / Fe modified HZSM-5 catalyst, which is then used to catalyze the conversion of volatiles from the co-pyrolysis of biomass and waste plastics into bio-oil rich in light aromatics. This method utilizes the synergistic catalytic effect of the Ni / Fe bimetallic compounds to simultaneously enhance the deoxygenation and aromatization reactions of the main oxygen-containing compounds in the biomass pyrolysis volatiles, and the polymerization, cyclization, and aromatization reactions of the main olefins and alkanes in the waste plastic pyrolysis volatiles, thereby increasing the yield of light aromatics during the co-catalytic pyrolysis process of biomass and waste plastics.

[0007] To achieve the above objectives, the present disclosure adopts the following technical solution: In a first aspect, this disclosure provides a method for producing light aromatics by co-pyrolysis of biomass and waste plastics, comprising: Under a nitrogen atmosphere, a mixture of biomass raw materials and waste plastics is subjected to a pyrolysis reaction to produce pyrolysis products; The pyrolysis products are contacted with a catalyst to produce conversion products; and The conversion product is subjected to condensation treatment to obtain a liquid product rich in light aromatics. The catalyst is a Ni and Fe supported HZSM-5 catalyst.

[0008] In some embodiments, in the Ni and Fe supported HZSM-5 catalyst, the total loading of Ni and Fe is 5%-10%, wherein the loading is the ratio of the mass of the supported element to the mass of the HZSM-5.

[0009] In some embodiments, in the Ni-Fe supported HZSM-5 catalyst, the mass ratio of Ni to Fe is 1:1 to 1:4.

[0010] In some embodiments, the mass ratio of the Ni- and Fe-supported HZSM-5 catalyst to the mixture is 1:1 to 2:1.

[0011] In some implementations, the biomass is selected from at least one of walnut shells, peanut shells, and hazelnut shells.

[0012] In some embodiments, the waste plastic is selected from at least one of high-density polyethylene, low-density polyethylene, polypropylene, and polystyrene.

[0013] In some embodiments, the mass ratio of the biomass to the waste plastic in the mixture is 3:1 to 1:3.

[0014] In some implementations, the pyrolysis temperature is 500-700°C.

[0015] In some implementations, the pyrolysis time is 15-30 min.

[0016] In some embodiments, the flow rate of the nitrogen gas is 100-200 mL / min.

[0017] In some embodiments, the Ni and Fe supported HZSM-5 catalyst is obtained by using calcined HZSM-5 molecular sieve as a support, loading Fe precursor and Ni precursor by impregnation under stirring conditions, and then sequentially drying and calcining.

[0018] In some embodiments, the stirring temperature is 40-50°C.

[0019] In some embodiments, the stirring temperature is 45°C.

[0020] In some implementations, the stirring time is 8-10 hours.

[0021] In some embodiments, the drying process is carried out at a temperature of 100-110°C.

[0022] In some embodiments, the drying process is carried out at a temperature of 105°C.

[0023] In some implementations, the drying process takes 12-24 hours.

[0024] In some embodiments, the calcination treatment is carried out at a temperature of 500-600°C.

[0025] In some embodiments, the calcination treatment is performed at a temperature of 550°C.

[0026] In some implementations, the roasting process takes 5-7 hours.

[0027] In some embodiments, the roasting process is carried out in an air atmosphere.

[0028] In some implementations, the Fe precursor is ferric nitrate.

[0029] In some implementations, the Ni precursor is nickel nitrate.

[0030] In some embodiments, the catalyst is placed in a layer with the mixture of biomass feedstock and waste plastics, and the catalyst does not come into contact with the mixture of biomass feedstock and waste plastics.

[0031] In some embodiments, the light aromatic hydrocarbon content in the liquid product rich in light aromatic hydrocarbons is greater than 55%, preferably 55-70%.

[0032] Compared with the prior art, this disclosure has the following beneficial effects: The catalytic pyrolysis method disclosed herein involves first preparing a Ni- and Fe-modified HZSM-5 catalyst. This catalyst is then used to largely convert the complex volatiles generated from the pyrolysis of a mixture of biomass and waste plastics into light aromatics. This disclosure utilizes the synergistic catalytic effect of the Ni-Fe bimetallic catalyst to simultaneously enhance the deoxygenation and aromatization reactions of the main oxygen-containing compounds in the biomass pyrolysis volatiles, and the polymerization, cyclization, and aromatization reactions of the main olefins and alkanes in the waste plastic pyrolysis volatiles. This solves the problem of HZSM-5's inefficient catalytic simultaneous and directional conversion of oxygen-containing compounds and aliphatic hydrocarbons. The method disclosed herein improves the yield and selectivity of light aromatics in the co-catalytic pyrolysis process of biomass and waste plastics, and inhibits catalyst carbon deposition and the formation of polycyclic aromatic hydrocarbons, achieving efficient production of light aromatics from the co-catalytic pyrolysis of biomass and waste plastics. Attached Figure Description

[0033] Figure 1 This is a flowchart illustrating a method for producing light aromatics by co-pyrolysis of biomass and waste plastics according to an embodiment of this disclosure.

[0034] Figure 2 Scanning electron microscope (SEM) images of Ni- and Fe-loaded HZSM-5 prepared for embodiments of this disclosure.

[0035] Figures 3 to 8 EDS analysis chromatogram of Ni and Fe loaded HZSM-5 prepared for embodiments of this disclosure. Detailed Implementation

[0036] To enable those skilled in the art to better understand the present disclosure, the technical solutions of the present disclosure will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present disclosure, and not all embodiments. Based on the embodiments of the present disclosure, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present disclosure.

[0037] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this disclosure are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of this disclosure described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0038] When a range of values ​​is provided, it should be understood that, unless the context explicitly specifies otherwise, every intermediate value between the upper and lower limits of the range (to one-tenth of the lower limit unit), as well as any other specified or intermediate value within the specified range, is included in this disclosure. The upper and lower limits of these smaller ranges may be independently included within the smaller range and also within this disclosure, subject to any expressly excluded limits within the specified range. When a specified range includes one or two limits, the range excluding any one or both of these included limits is also included in this disclosure.

[0039] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure pertains. Although any methods and materials similar to or equivalent to those described herein may also be used in the practice or testing of this disclosure, preferred methods and materials are now described.

[0040] Upon reading this disclosure, it will be apparent to those skilled in the art that each individual embodiment described and illustrated herein has discrete components and features that can be readily separated from or combined from features of any other several embodiments without departing from the scope or spirit of this disclosure. Any of the described methods may be performed in the order of the events or in any other logically possible order.

[0041] Unless otherwise stated, embodiments of this disclosure will employ techniques from the fields of chemistry, organic chemistry, organometallic chemistry, physics, and petrochemicals, which are within the skill level of those skilled in the art. These techniques are well explained in the literature.

[0042] The following examples are provided to demonstrate to those skilled in the art how to perform the disclosed and claimed methods and how to use the disclosed and claimed compositions and compounds in accordance with the full disclosure and description. Efforts have been made to ensure the accuracy of figures (e.g., quantities, temperatures, etc.), but some errors and deviations should be taken into account.

[0043] Light aromatic hydrocarbons such as benzene, toluene, xylene, and ethylbenzene are key raw materials for petrochemicals and organic synthesis. Currently, they are mainly extracted and prepared from fossil fuels. However, the reserves of fossil fuels are decreasing and their utilization process causes environmental pollution problems. Therefore, there is an urgent need to find sustainable and environmentally friendly alternative raw materials for aromatic hydrocarbon production.

[0044] Biomass, as the only renewable carbon-containing resource, can produce light aromatics through catalytic pyrolysis, making it an excellent alternative to fossil fuels. However, the hydrogen-poor and oxygen-rich nature of biomass results in low yields and selectivity of light aromatics during its catalytic pyrolysis process, and the catalyst is prone to carbon buildup and deactivation. Waste plastics are a high-quality hydrogen-rich resource that can provide a supplementary hydrogen source for the rapid catalytic pyrolysis process of biomass.

[0045] However, the volatiles from the co-pyrolysis of biomass and waste plastics are complex, mainly composed of oxygen-containing compounds (phenols, furans, acids, aldehydes, ketones, etc.) and aliphatic hydrocarbons (olefins, alkanes, etc.). The commonly used HZSM-5 catalyst in this field is difficult to efficiently catalyze the simultaneous and directional conversion of oxygen-containing compounds and aliphatic hydrocarbons due to its acidic sites. Therefore, existing co-catalytic pyrolysis methods for biomass and waste plastics still face the need to further improve the yield and selectivity of light aromatics, and to suppress catalyst coking and the formation of polycyclic aromatic hydrocarbons. Therefore, there is an urgent need to develop a method for the efficient production of light aromatics from the co-catalytic pyrolysis of biomass and waste plastics.

[0046] To overcome the shortcomings of the prior art, the present disclosure aims to provide a method for producing light aromatics through co-pyrolysis of biomass and waste plastics. This method employs a co-impregnation method to prepare a Ni and Fe-supported HZSM-5 catalyst, which is then used to catalyze the conversion of volatiles from the co-pyrolysis of biomass and waste plastics into bio-oil rich in light aromatics. This method utilizes the synergistic catalytic effect of the Ni and Fe bimetals to simultaneously enhance the deoxygenation and aromatization reactions of the main oxygen-containing compounds in the biomass pyrolysis volatiles, and the polymerization, cyclization, and aromatization reactions of the main olefin and alkanes in the waste plastic pyrolysis volatiles, thereby increasing the yield of light aromatics during the co-catalytic pyrolysis process of biomass and waste plastics.

[0047] The first aspect of this disclosure provides a method for producing light aromatics by co-pyrolysis of biomass and waste plastics, comprising: Under a nitrogen atmosphere, a mixture of biomass raw materials and waste plastics is subjected to a pyrolysis reaction to produce pyrolysis products; The pyrolysis products are contacted with a catalyst to produce conversion products; and The conversion product is subjected to condensation treatment to obtain a liquid product rich in light aromatics.

[0048] The catalyst is a Ni and Fe supported HZSM-5 catalyst, which will also be referred to as "modified HZSM-5" in the following text.

[0049] Here, "pyrolysis" refers to the thermal conversion of biomass feedstock and waste plastics under high temperature and in the absence of oxygen. In embodiments of this disclosure, when processed at these temperatures, the biomass feedstock is converted to a liquid product (i.e., bio-oil). Furthermore, the components of the liquid product can be separated from each other, thus allowing them to be used as chemicals and fuels for specific applications.

[0050] In some embodiments, the pyrolysis temperature can be 500-700°C. As an example, the pyrolysis temperature can be 500°C, 550°C, 600°C, 650°C, 700°C, or any number between any two of the above values.

[0051] In some implementations, the pyrolysis time is 15-30 min. As an example, the pyrolysis time can be 15 min, 16 min, 17 min, 18 min, 19 min, 20 min, 21 min, 22 min, 23 min, 24 min, 25 min, 26 min, 27 min, 28 min, 29 min, 30 min, and any number between any two of the above values.

[0052] In some embodiments, the nitrogen flow rate is 100-200 mL / min. As an example, the nitrogen flow rate can be 100 mL / min, 110 mL / min, 120 mL / min, 130 mL / min, 140 mL / min, 150 mL / min, 160 mL / min, 170 mL / min, 180 mL / min, 190 mL / min, 200 mL / min, and any number between any two of the above values.

[0053] The biomass feedstock disclosed herein can be pyrolyzable biomass co-pyrolyzed with waste plastics to improve the hydrogen-poor and oxygen-rich characteristics of biomass, thereby increasing the yield and selectivity of light aromatics. In some embodiments, the biomass can be at least one of walnut shells, peanut shells, and hazelnut shells. The waste plastics can be at least one of high-density polyethylene, low-density polyethylene, polypropylene, and polystyrene.

[0054] In some embodiments, the mass ratio of biomass to waste plastic in the mixture can be 3:1 to 1:3. As an example, the mass ratio of biomass to waste plastic can be 3:1, 2:1, 1:1, 1:2, 1:3, and any number between any two of the above values.

[0055] In some embodiments, the catalyst is placed in a layer with the mixture of biomass feedstock and waste plastics, and the catalyst does not come into contact with the mixture of biomass feedstock and waste plastics. Therefore, the catalyst can be recycled and reused.

[0056] As for the catalyst, the Ni and Fe supported HZSM-5 catalyst is obtained by using calcined HZSM-5 molecular sieve as a support, loading Fe precursor and Ni precursor by impregnation under stirring conditions, and then subjecting them to drying and calcination treatments in sequence.

[0057] The catalyst disclosed herein utilizes the synergistic catalytic effect of Ni and Fe bimetals to simultaneously enhance the deoxygenation and aromatization reactions of oxygen-containing compounds, the main components of volatiles in biomass pyrolysis, and the polymerization, cyclization, and aromatization reactions of olefins and alkanes, the main components of volatiles in waste plastic pyrolysis, thereby increasing the yield of light aromatics in the co-catalytic pyrolysis process of biomass and waste plastics.

[0058] In some embodiments, the total loading of Ni and Fe in the Ni-Fe supported HZSM-5 catalyst is 5%-10%. Here, the loading is the ratio of the mass of the supported element to the mass of the HZSM-5. As an example, the total loading of Ni and Fe can be 5.0%, 5.5%, 6.0%, 6.5%, 7.0%, 7.5%, 8.0%, 8.5%, 9.0%, 9.5%, 10%, or any number between any two of the above values.

[0059] In some embodiments, the mass ratio of Ni to Fe in the Ni-Fe supported HZSM-5 catalyst is 1:1 to 1:4. As an example, the mass ratio of Ni to Fe can be 1:1, 1:2, 1:3, 1:4, or any number between any two of the above values.

[0060] In some embodiments, the mass ratio of the Ni- and Fe-supported HZSM-5 catalyst to the mixture of biomass feedstock and waste plastics is 1:1 to 2:1.

[0061] In some embodiments, the Fe precursor is ferric nitrate and the Ni precursor is nickel nitrate.

[0062] In some implementation schemes, the specific methods for preparing Ni and Fe supported HZSM-5 catalysts are as follows: ZSM-5 was calcined at high temperature for 5 hours to obtain activated ZSM-5 (i.e., HZSM-5). Ni(NO3)2 6H2O and Fe(NO3)3 Mix with 9H2O to obtain an aqueous solution of nitrate; HZSM-5 was dissolved in the nitrate aqueous solution, stirred until homogeneous, dried to constant weight, and ground to obtain the ground powder; and The ground powder was calcined in air to obtain Ni and Fe supported HZSM-5 catalyst.

[0063] In some embodiments, the stirring temperature is 40-50°C. As an example, the stirring temperature can be 40°C, 41°C, 42°C, 43°C, 44°C, 45°C, 46°C, 47°C, 48°C, 49°C, 50°C, and any number between any two of the above values.

[0064] In a preferred embodiment, the stirring temperature is 45°C.

[0065] In some implementations, the stirring time is 8-10 hours. As an example, the stirring time can be 8 hours, 8.5 hours, 9 hours, 9.5 hours, 10 hours, or any number between any two of the above values.

[0066] In some embodiments, the drying temperature is 100-110°C. As an example, the drying temperature can be 100°C, 101°C, 102°C, 103°C, 104°C, 105°C, 106°C, 107°C, 108°C, 109°C, 110°C, or any number between any two of the above values.

[0067] In a preferred embodiment, the drying temperature is 105°C.

[0068] In some implementations, the drying process takes 12-24 hours. As an example, the drying process can take 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24 hours, or any number between any two of the above values.

[0069] In some embodiments, the calcination temperature is 500-600°C. As an example, the calcination temperature can be 500°C, 510°C, 520°C, 530°C, 540°C, 550°C, 560°C, 570°C, 580°C, 590°C, 600°C, and any number between any two of the above values.

[0070] In a preferred embodiment, the calcination temperature is 550°C.

[0071] In some implementations, the roasting process takes 5-7 hours. As an example, the roasting process can take 5 hours, 5.5 hours, 6 hours, 6.5 hours, 7 hours, or any number between any two of the above values.

[0072] In some embodiments, the roasting process is carried out in an air atmosphere.

[0073] In the specific implementation plan, such as Figure 1As shown, the method for producing light aromatics by co-pyrolysis of biomass and waste plastics includes the following steps: S1. Preparation of modified HZSM-5 catalyst: ZSM-5 was activated by calcination at 550℃ for 5 hours, and Ni(NO3)2 was prepared. 6H2O, Fe(NO3)3 Ni and Fe modified HZSM-5 was prepared by dissolving HZSM-5 in a nitrate solution using a 9H2O mixed aqueous solution, stirring until homogeneous, drying to constant weight, grinding, and calcining in air atmosphere. S2. Catalytic pyrolysis: A mixture of biomass and waste plastics and a catalyst are placed in a quartz reactor for catalytic pyrolysis. The raw material is located in the lower layer, and the catalyst is located in the upper layer. The volatiles generated by the pyrolysis of the raw material flow through the catalyst bed, and the gases, bio-oil rich in light aromatics, and solid products generated by the pyrolysis are collected.

[0074] In some embodiments, the light aromatic hydrocarbon content in the liquid product rich in light aromatic hydrocarbons is greater than 55%, preferably 55-70%.

[0075] Therefore, this disclosure improves the yield and selectivity of light aromatics in the co-catalytic pyrolysis process of biomass and waste plastics, and inhibits catalyst carbon deposition and the formation of polycyclic aromatic hydrocarbons, thereby achieving efficient production of light aromatics from the co-catalytic pyrolysis of biomass and waste plastics.

[0076] To make the embodiments of this disclosure easier to understand, the present disclosure will be described in detail below with reference to the embodiments. These embodiments are for illustrative purposes only and are not limited to the application scope of this disclosure.

[0077] Unless otherwise specified, the specific operations and processing methods or conditions not described in the following embodiments are conventional methods in the art or are performed in accordance with the techniques or conditions described in the literature in the art or in accordance with the product manual.

[0078] Unless otherwise specified, all reagents or instruments used in the following examples that do not specify the manufacturer are commercially available products and conventional instruments in the field.

[0079] In the following examples, unless otherwise specified, all percentages are weight percentages.

[0080] None of the chemicals underwent secondary purification.

[0081] The specific testing methods disclosed herein are as follows: The scanning electron microscope (SEM) images were obtained using a Merlin Compact thermal field emission scanning electron microscope from Zeiss GmbH, Germany, based on an accelerating voltage of 20 kV and a magnification of 10,000x.

[0082] EDS analysis was performed using the Oxford EDS appendix, measured at 2000x magnification.

[0083] The composition of the bio-oil was analyzed using a Shimadzu GP2020NX gas chromatograph-mass spectrometer with a Shimadzu SH-Rxi-5Sil MS column (30 m × 0.25 mm × 0.25 μm). The injection split ratio was 6:1, and the column temperature was set to 40℃ initially and held for 1 min, then increased to 280℃ at a rate of 3℃ / min and held for 2 min.

[0084] Example 1 ZSM-5 was calcined at 550 °C for 5 hours. 1.8084 g Fe(NO3)3·9H2O and 1.2387 g Ni(NO3)·6H2O were weighed and dissolved in 30 mL of deionized water. 10 g of calcined HZSM-5 molecular sieve was added. The solution was placed in a magnetic stirrer and stirred at 45 °C for 8 hours at a stirring rate of 500 rpm. After stirring, the solution was dried in an oven at 105 °C for 12 hours. The dried catalyst precursor was thoroughly ground and then calcined in a muffle furnace at 550 °C for 5 hours in air atmosphere to obtain the Ni and Fe supported HZSM-5 catalyst (metal loading 5%, Ni to Fe mass ratio 1:1).

[0085] Subsequently, 1 g of mixed sample (walnut shell and HDPE mass ratio of 1:1) and 1 g of catalyst were placed in a quartz reactor, with the sample and catalyst separated by quartz wool. The loaded quartz reactor was placed in the room temperature zone at the top of the furnace. N2 was purged at a rate of 100 mL / min for 10 min, and then the tubular furnace was heated to 600 °C. Once the temperature stabilized, the quartz reactor was quickly moved to the central heating zone of the tubular furnace, and the pyrolysis reaction proceeded for 15 min. The pyrolysis gas was purged out of the tubular furnace reactor, the bio-oil was absorbed by a condenser (a wash bottle containing dichloromethane under ice-water bath conditions), and the gaseous products were collected in an aluminum foil gas bag after filtration and drying.

[0086] The composition of the obtained bio-oil was analyzed, and the content of light aromatic hydrocarbons in the bio-oil was 65.74%, of which the contents of benzene, toluene, ethylbenzene and xylene were 14.08%, 26.21%, 3.32% and 22.13%, respectively.

[0087] Example 2 ZSM-5 was calcined at 550 °C for 5 hours. 2.5318 g of Fe(NO3)3·9H2O and 1.7341 g of Ni(NO3)·6H2O were weighed and dissolved in 30 mL of deionized water. 10 g of calcined HZSM-5 molecular sieve was added. The solution was placed in a magnetic stirrer and stirred at 45 °C for 8 hours at a stirring rate of 500 rpm. After stirring, the solution was dried in an oven at 105 °C for 12 hours. The dried catalyst precursor was thoroughly ground and then calcined in a muffle furnace at 550 °C for 5 hours in air atmosphere to obtain the Ni and Fe supported HZSM-5 catalyst (metal loading 7%, Ni to Fe mass ratio 1:1).

[0088] Subsequently, 1 g of mixed sample (walnut shell and HDPE mass ratio of 1:1) and 1 g of catalyst were placed in a quartz reactor, with the sample and catalyst separated by quartz wool. The loaded quartz reactor was placed in the room temperature zone at the top of the furnace. N2 was purged at a rate of 100 mL / min for 10 min, and then the tubular furnace was heated to 600 °C. Once the temperature stabilized, the quartz reactor was quickly moved to the central heating zone of the tubular furnace, and the pyrolysis reaction proceeded for 15 min. The pyrolysis gas was purged out of the tubular furnace reactor, the bio-oil was absorbed by a condenser (a wash bottle containing dichloromethane under ice-water bath conditions), and the gaseous products were collected in an aluminum foil gas bag after filtration and drying.

[0089] The composition of the obtained bio-oil was analyzed. The content of light aromatic hydrocarbons in the bio-oil was 57.10%, of which benzene, toluene, ethylbenzene and xylene accounted for 14.40%, 21.96%, 2.91% and 17.82%, respectively.

[0090] Example 3 ZSM-5 was calcined at 550℃ for 5 hours. 3.3757 g of Fe(NO3)3·9H2O and 1.1561 g of Ni(NO3)·6H2O were weighed and dissolved in 30 mL of deionized water. 10 g of calcined HZSM-5 molecular sieve was added. The solution was placed in a magnetic stirrer and stirred at 45℃ for 8 hours at a stirring rate of 500 rpm. After stirring, the solution was dried in an oven at 105℃ for 12 hours. The dried catalyst precursor was thoroughly ground and then calcined in a muffle furnace at 550℃ for 5 hours in air atmosphere to obtain the Ni and Fe supported HZSM-5 catalyst (metal loading 7%, Ni to Fe mass ratio 1:2).

[0091] Subsequently, 1 g of mixed sample (walnut shell and HDPE mass ratio of 1:1) and 1 g of catalyst were placed in a quartz reactor, with the sample and catalyst separated by quartz wool. The loaded quartz reactor was placed in the room temperature zone at the top of the furnace. N2 was purged at a rate of 100 mL / min for 10 min, and then the tubular furnace was heated to 600 °C. Once the temperature stabilized, the quartz reactor was quickly moved to the central heating zone of the tubular furnace, and the pyrolysis reaction proceeded for 15 min. The pyrolysis gas was purged out of the tubular furnace reactor, the bio-oil was absorbed by a condenser (a wash bottle containing dichloromethane under ice-water bath conditions), and the gaseous products were collected in an aluminum foil gas bag after filtration and drying.

[0092] The composition of the obtained bio-oil was analyzed, and the content of light aromatic hydrocarbons in the bio-oil was 69.80%, of which the contents of benzene, toluene, ethylbenzene and xylene were 17.47%, 26.68%, 3.25% and 22.40%, respectively.

[0093] Example 4 ZSM-5 was calcined at 550℃ for 5 hours. 4.0508 g of Fe(NO3)3·9H2O and 0.6936 g of Ni(NO3)·6H2O were weighed and dissolved in 30 mL of deionized water. 10 g of calcined HZSM-5 molecular sieve was added. The solution was placed in a magnetic stirrer and stirred at 45℃ for 8 hours at a stirring rate of 500 rpm. After stirring, the solution was dried in an oven at 105℃ for 12 hours. The dried catalyst precursor was thoroughly ground and then calcined in a muffle furnace at 550℃ for 5 hours in air atmosphere to obtain the Ni and Fe supported HZSM-5 catalyst (metal loading 7%, Ni to Fe mass ratio 1:4).

[0094] Subsequently, 1 g of mixed sample (walnut shell and HDPE mass ratio of 1:1) and 1 g of catalyst were placed in a quartz reactor, with the sample and catalyst separated by quartz wool. The loaded quartz reactor was placed in the room temperature zone at the top of the furnace. N2 was purged at a rate of 100 mL / min for 10 min, and then the tubular furnace was heated to 600 °C. Once the temperature stabilized, the quartz reactor was quickly moved to the central heating zone of the tubular furnace, and the pyrolysis reaction proceeded for 15 min. The pyrolysis gas was purged out of the tubular furnace reactor, the bio-oil was absorbed by a condenser (a wash bottle containing dichloromethane under ice-water bath conditions), and the gaseous products were collected in an aluminum foil gas bag after filtration and drying.

[0095] The composition of the obtained bio-oil was analyzed, and the content of light aromatic hydrocarbons in the bio-oil was 55.45%, of which the contents of benzene, toluene, ethylbenzene and xylene were 12.92%, 24.35%, 2.48% and 15.69%, respectively.

[0096] The components of the bio-oils obtained in Examples 1 to 4 are summarized in Table 1.

[0097] Table 1

[0098] Figure 2 The image shows a scanning electron microscope (SEM) image of the Ni- and Fe-supported HZSM-5 catalyst prepared in Example 1. Figure 2 It can be seen that the loaded molecular sieve still retains the characteristic crystal form of the parent material, with clear grain outlines and good dispersion. No obvious grain agglomeration or breakage was observed, and no obvious metal element agglomerates were observed on the grain surface. This result indicates that the loaded Ni and Fe have a good dispersion effect and do not significantly damage the crystal structure and morphology of the molecular sieve, thus maintaining the integrity of the molecular sieve framework.

[0099] Figure 3 The image shows the EDS analysis of the Ni and Fe supported HZSM-5 catalyst prepared in Example 1. Figures 4 to 8 The following are EDS analysis diagrams of Si, O, Al, Fe and Ni elements of the Ni- and Fe-supported HZSM-5 catalyst prepared in Example 1.

[0100] from Figures 3 to 8 It can be seen that the signals of the three framework elements, Si, O, and Al, maintain a uniform and continuous distribution, indicating that the loading behavior did not damage the framework structure of the HZSM-5 molecular sieve, which is consistent with the results of SEM characterization. The characteristic signals of Ni and Fe metals are uniformly distributed in the scanning area, and the distribution areas highly overlap, without obvious local enrichment or agglomeration of single metals, indicating that the two metals are synchronously and uniformly dispersed on the surface of the HZSM-5 support.

[0101] The above content is only for illustrating the technical concept of this disclosure and should not be used to limit the scope of protection of this disclosure. Any modifications made to the technical solution based on the technical concept proposed in this disclosure shall fall within the scope of protection of the claims of this disclosure.

Claims

1. A method for producing light aromatics by co-pyrolysis of biomass and waste plastics, characterized in that, The method includes: Under a nitrogen atmosphere, a mixture of biomass raw materials and waste plastics is subjected to a pyrolysis reaction to produce pyrolysis products; The pyrolysis products are contacted with a catalyst to produce conversion products; and The conversion product is subjected to condensation treatment to obtain a liquid product rich in light aromatics. The catalyst is a Ni and Fe supported HZSM-5 catalyst.

2. The method according to claim 1, characterized in that, In the Ni and Fe supported HZSM-5 catalyst, the total loading of Ni and Fe is 5%-10%, wherein the loading is the ratio of the mass of the supported element to the mass of HZSM-5, and the mass ratio of Ni to Fe is 1:1-1:

4.

3. The method according to claim 1, characterized in that, The mass ratio of the Ni and Fe supported HZSM-5 catalyst to the mixture is 1:1 to 2:

1.

4. The method according to claim 1, characterized in that, The biomass is selected from at least one of walnut shells, peanut shells, and hazelnut shells; Alternatively, the waste plastic is selected from at least one of high-density polyethylene, low-density polyethylene, polypropylene, and polystyrene.

5. The method according to claim 1, characterized in that, The mass ratio of the biomass to the waste plastic in the mixture is 3:1 to 1:

3.

6. The method according to claim 1, characterized in that, The pyrolysis temperature is 500-700℃, the pyrolysis time is 15-30 min, and the nitrogen flow rate is 100-200 mL / min.

7. The method according to claim 1, characterized in that, The Ni and Fe supported HZSM-5 catalyst was obtained by using calcined HZSM-5 molecular sieve as a support, loading Fe precursor and Ni precursor by impregnation under stirring conditions, and then subjecting them to drying and calcination treatments in sequence.

8. The method according to claim 7, characterized in that, The stirring temperature is 40-50℃, preferably 45℃, and the stirring time is 8-10 hours; Alternatively, the drying temperature is 100-110°C, preferably 105°C, and the drying time is 12-24 hours; Alternatively, the calcination temperature is 500-600℃, preferably 550℃, the calcination time is 5-7 hours, and the calcination is carried out in an air atmosphere; Alternatively, the Fe precursor is ferric nitrate; Alternatively, the Ni precursor may be nickel nitrate.

9. The method according to claim 1, characterized in that, The catalyst is placed in a layer with the mixture of biomass raw materials and waste plastics, and the catalyst does not come into contact with the mixture of biomass raw materials and waste plastics.

10. The method according to claim 1, characterized in that, The liquid product rich in light aromatics contains more than 55% light aromatics, preferably 55-70%.

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