Method for oxygen-mediated efficient catalytic recovery of gasoline product from waste polyolefin plastic

Abstract

The application belongs to the field of solid waste catalysis, and particularly relates to a method for efficiently catalytically recycling gasoline products from waste polyolefin plastics under the mediation of oxygen. The method comprises the following steps: mixing a metal-acid catalyst with waste polyolefin plastics, and reacting in a mixed gas containing oxygen under normal pressure; separating the reaction liquid to obtain gasoline products; the metal-acid catalyst comprises a pretreated metal catalyst and a pretreated solid acid catalyst. The application adopts a metal-acid catalyst to optimize the reaction conditions for the degradation of polyolefin to aromatic chemicals under different oxygen concentrations, so as to obtain higher catalytic activity and selectivity of liquid gasoline products. In addition, the application first proposes a new air-assisted polyolefin catalytic recycling system, which solves the limitation of harsh reaction conditions in traditional polyolefin catalytic recycling, and is expected to realize large-scale application.

Description

Technical Field

[0001] This invention relates to the field of solid waste catalysis technology, and in particular to an oxygen-mediated method for the efficient catalytic recovery of gasoline products from waste polyolefin plastics. Background Technology

[0002] Plastics have been widely used since the 1950s due to their low cost, ease of use, and excellent chemical stability, and are ubiquitous in daily life. With the continuous increase in plastic production, it is projected that 500 million tons of waste plastic will be generated by 2050, and more than 80% of this waste plastic will be landfilled or incinerated. Because of their excellent chemical stability, plastics are difficult to degrade in the natural environment, which not only pollutes soil and water bodies but also seriously encroaches on the living space of organisms, causing serious environmental problems. Therefore, new recycling strategies and technologies are urgently needed to address the global plastic crisis. Currently, chemical recycling technology for plastics is considered one of the effective strategies to solve the plastic crisis. Unlike the low-value recycling of traditional mechanical recycling, this technology uses chemical means to convert high molecular weight polymers into low molecular weight, high-value-added small molecules (such as solid paraffin, liquid fuels, and gaseous products). These small molecule products obtained from recycled waste plastics can be reused as raw materials for chemical production reactions, achieving economic circular value-added utilization, which has attracted widespread attention from the industry.

[0003] Among numerous chemical recycling technologies, converting polyolefins into aromatic chemicals is considered a method with significant industrial applications. Aromatic compounds are a class of chemicals with high economic value; benzene, toluene, and xylene are major components of gasoline, while linear alkylbenzenes are key raw materials for surfactant production. These substances, due to their high economic value, have become attractive target products in plastic degradation. Researchers utilize traditional pyrolysis reactions to subject polyolefins to random C-C bond cleavage at high temperatures, producing alkanes, alkenes, and aromatic hydrocarbons. Finally, through cooling and coagulation, aromatic hydrocarbons can be separated from the mixture, and ultimately, through refining, aromatic chemicals meeting the requirements of chemical production are obtained. This process can effectively degrade and utilize waste plastics and achieve efficient energy recovery by recovering the energy generated by the high-temperature reaction. However, excessively high reaction temperatures and low aromatic hydrocarbon selectivity hinder the further development of this process. To reduce the severity of reaction conditions, shorten reaction time, improve aromatic hydrocarbon selectivity, and control product distribution, the introduction of appropriate catalysts for catalytic pyrolysis has gradually become the main process route for polyolefin degradation. Therefore, designing a simple, low-cost, and highly selective process for the preparation of aromatic chemicals from polyolefins is crucial.

[0004] The aromatization strategy for waste polyolefins is an emerging chemical recycling technology in recent years, commonly using zeolite catalysts to degrade polyolefins into high-value-added liquid fuels. However, currently reported aromatization reactions require excessively high temperatures, and the product selectivity is often too low, resulting in relatively low economic efficiency for this recycling strategy. Therefore, the selection of highly active and selective catalysts, as well as advanced catalytic systems, is crucial. Existing technologies are as follows:

[0005] (1) The degradation of polyolefins into gasoline products was achieved using a solid acid catalyst. The optimal conditions for this technology were: an argon atmosphere, a temperature of 500-700℃, and a reaction time of 24 h, which yielded an aromatic selectivity of 43.9 mol% and produced a series of low-value gases. (Source: J. Anal. Appl. Pyrolysis. 51, 107–126)

[0006] (2) A fluidized bed apparatus for pyrolysis and gasification was designed for the degradation of mixed plastics into gasoline products. Polyolefins can be degraded into gasoline products without the addition of an additional catalyst. The optimal reaction conditions were: 700°C under an argon atmosphere, reaction time of 2 h, yielding an aromatic selectivity of 18.0 mol% (Source: Energy & Fuels. 24, 1389–1395).

[0007] (3) By introducing the greenhouse gas CO2, polyolefins and CO2 are converted into aromatic products and CO using Cu-Fe3O4 and Zn / ZSM-5 catalysts, achieving "dual waste conversion". The optimal reaction conditions are: 3 MPa CO2, 360 °C, and a reaction time of 1 h, which yields an aromatic selectivity of 64 wt.% (Source: CCS Chem. 1–23).

[0008] However, since the aromatization of polyolefins is a typical endothermic reaction, the rate-determining CH activation step usually requires a high temperature. Therefore, below 300°C, the activity is generally poor, the efficiency is low, and a long reaction time is required to achieve a conversion rate close to 70 wt.% and an aromatic selectivity of less than 50%. Therefore, there is an urgent need to develop a recovery method with high aromatic selectivity and high conversion rate under low-temperature conditions. Summary of the Invention

[0009] To address the low gasoline fuel yield in current polyolefin aromatization reactions, this invention provides an oxygen-mediated method for the efficient catalytic recovery of gasoline from waste polyolefin plastics. Applied to the aromatization reaction of polyolefins, this method achieves efficient conversion of polyolefins into gasoline. The invention employs a physical mixing method of a supported metal catalyst and a solid acid catalyst, testing catalytic performance under different oxygen concentrations to explore optimal reaction conditions, thereby obtaining higher catalytic activity and liquid gasoline selectivity. Furthermore, this invention demonstrates that this type of catalyst maintains high stability in an air-catalyzed environment and achieves a plastic conversion rate approaching 100 wt.% and an alkylbenzene selectivity of 77.5 mol%. This invention not only enables efficient and selective degradation of polyolefins at relatively low reaction temperatures but also provides important guidance for the industrial degradation of polyolefins to produce gasoline fuel.

[0010] The present invention aims to provide an oxygen-mediated, highly efficient catalytic recovery method for gasoline products from waste polyolefin plastics, comprising the following steps: mixing a metal-acid catalyst with waste polyolefin plastics and reacting the mixture in an oxygen-containing gas mixture at atmospheric pressure; separating the reaction liquid to obtain gasoline products; wherein the metal-acid catalyst comprises a pretreated metal catalyst and a pretreated solid acid catalyst; and the gasoline products comprise gaseous low-carbon alkanes and liquid products, wherein the liquid products comprise alkylbenzenes, naphthalene, long-chain olefins, and long-chain alkanes.

[0011] In some embodiments of the present invention, the oxygen content in the mixed gas is 10-50 vol%.

[0012] The mixed gas also includes inactive gases, including nitrogen and / or argon.

[0013] In this invention, the oxygen-containing mixed gas is preferably air.

[0014] In some embodiments of the present invention, the waste polyolefin plastic is selected from one or more of low-density polyethylene plastic, high-density polyethylene plastic, and polypropylene plastic;

[0015] The waste polyolefin plastic is in powder or block form, with a size of 1-5cm.

[0016] In some embodiments of the present invention, the metal-acid catalyst is prepared by the following method:

[0017] The solid acid catalyst and the metal-based catalyst were dried.

[0018] The dried supported metal-based catalyst was calcined in a reducing gas atmosphere to obtain a pretreated metal catalyst.

[0019] The dried solid acid catalyst was calcined in air at 500-600℃ for 2-4 hours to obtain pretreated solid acid catalyst B.

[0020] The pretreated catalyst A and pretreated catalyst B were mixed and ground to obtain the metal-acid catalyst.

[0021] In this invention, under a reducing atmosphere, the metal catalyst is reduced to ensure that it is in a metallic state rather than a reduced state before being added to the reaction.

[0022] In this invention, the solid acid catalyst can have its surface impurities removed after calcination, because zeolites are usually prepared by cation exchange, which requires the removal of impurities.

[0023] In some embodiments of the present invention, the solid acid catalyst is selected from one or more of HZSM-5, USY, and SAPO-34;

[0024] The metal in the metal-based catalyst is one or more of Pd, Pt, Ru, Ni, Ir, and Co;

[0025] The support for the metal-based catalyst is one or more of C, CeO2, SiO2, and TiO2;

[0026] Specifically, the metal-based catalyst of the present invention includes one or more of Ru / C, Ni / C, Pd / C, Ir / C, Ru / CeO2, Ru / SiO2, and Ru / TiO2 catalysts, preferably Ru / C, Ni / C, Pd / C, and Ir / C; more preferably Ru / C; all of the above catalysts are commercially available products.

[0027] The metal-based catalyst has a metal loading of 1-10 wt.%.

[0028] In some embodiments of the present invention, the reducing gas atmosphere includes hydrogen and inactive gases, wherein the concentration of hydrogen is 5-10 vol%, and the inactive gases are nitrogen and / or argon.

[0029] In some embodiments of the present invention, the calcination temperature is 300°C and the calcination time is 2-4 hours.

[0030] In some embodiments of the present invention, the mass ratio of the pretreated catalyst A to the pretreated catalyst B is 1:(4-8).

[0031] In some embodiments of the present invention, the mass ratio of the pretreated metal catalyst, the pretreated solid acid catalyst and the waste polyolefin plastic is 1:(4-8):(20-100).

[0032] In some embodiments of the present invention, the reaction conditions are as follows: the reaction temperature is 220-300°C, the reaction time is 1-12 h, and the reaction stirring rate is 200-1200 rpm.

[0033] The technical solution of the present invention has the following advantages compared with the prior art:

[0034] (1) This invention is the first to use O2 to promote the aromatization reaction of polyolefins, solving the problems of poor reactivity and low selectivity of aromatics in the traditional degradation of plastics. By introducing oxygen, this invention improves the slow activation of CH bonds in the aromatization reaction of polyolefins, because the introduction of O2 can play a thermodynamic cascading role, breaking the previous thermodynamically limited barrier. On the other hand, oxygen can promptly consume the H2 produced by the aromatization reaction, which kinetically helps the overall reaction equilibrium to shift to the positive direction.

[0035] (2) The present invention can use the “combustion-like reaction” that occurs on the catalyst surface of O2 to thermodynamically regulate the overall aromatization reaction, thereby significantly reducing the temperature of the polyolefin aromatization reaction and thus reducing the process cost.

[0036] (3) The catalyst involved in this invention has extremely high stability under air conditions and still maintains high catalytic activity and selectivity for liquid gasoline after 5 reaction cycles. Attached Figure Description

[0037] To make the content of this invention easier to understand, the invention will be further described in detail below with reference to specific embodiments and accompanying drawings, wherein...

[0038] Figure 1 This is a photograph of the 50ml reactor of the present invention.

[0039] Figure 2 This is a graph showing the aromatization properties of polyolefins at different temperatures under normal atmospheric pressure according to the present invention.

[0040] Figure 3 This invention relates to the liquid selectivity of polyolefin aromatization reactions under mixed gases with different O2 contents.

[0041] Figure 4 This invention relates to the liquid selectivity of polyolefin aromatization reactions under mixed gases with different O2 contents.

[0042] Figure 5 This is a graph showing the aromatization properties of polyolefins at different temperatures under normal atmospheric pressure according to the present invention.

[0043] Figure 6 This is a graph showing the performance of polyolefin aromatization stability test under normal air pressure according to the present invention;

[0044] Figure 7 This is a physical image of the 2L reactor of the present invention;

[0045] Figure 8 This is a photograph of the liquid gasoline product after the large-scale polyolefin aromatization reaction of this invention.

[0046] Figure 9 This is a performance diagram showing the liquid yield after the atmospheric pressure aromatization reaction of polyolefins in this invention. Detailed Implementation

[0047] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can better understand and implement the present invention. However, the embodiments described are not intended to limit the present invention.

[0048] Example 1

[0049] This embodiment provides a method for the efficient catalytic recovery of gasoline products from waste polyolefin plastics via oxygen-mediated processes, as detailed below:

[0050] I. Preparation of catalyst materials, as detailed below:

[0051] (1) Weigh 50g of commercial HZSM-5 and 25g of commercial Ru / C, Ni / C, Pd / C, Ir / C, Ru / CeO2, Ru / SiO2 and Ru / TiO2 catalysts respectively and put them into an oven at 100℃ and dry for 8h to ensure that there is no moisture.

[0052] (2) Reduction treatment: The commercial Ru / C, Ni / C, Pd / C and Ir / C catalysts obtained from drying in step (1) were placed in a tube furnace and calcined at 300°C for 2 hours in a H2 / Ar (H2 / 5 Vol%) mixture to obtain the reduced metal catalysts.

[0053] (3) Calcination treatment: The dried HZSM-5 catalyst obtained in step (1) is placed in a muffle furnace and calcined in air at 500°C for 2 hours to obtain the calcined HZSM-5 catalyst.

[0054] (4) Grinding: The reduced metal catalyst and the calcined HZSM-5 catalyst were physically mixed at a mass ratio of 1:4, and after repeated grinding, mixed catalyst powders of metal Ru, Ni, Pd and Ir were obtained respectively.

[0055] (II) Application of Catalyst Materials

[0056] (1) Weigh 250mg of the mixed catalyst powder containing metals Ru, Ni, Pd and Ir prepared in step (1), of which 50mg is the reduced metal catalyst and 200mg is the calcined HZSM-5 zeolite.

[0057] (2) Weigh 1g of low-density polyolefin powder (LDPE) and place it into a high-pressure reactor. See the schematic diagram of the 50ml reactor. Figure 1 The reaction was carried out in air at a temperature of 280℃, a stirring rate of 400 rpm, and a reaction time of 12 h. After the reaction was completed, the remaining gas was collected using a gas bag. Subsequently, the liquid and solid products were dissolved and dispersed in dichloromethane, and separated by centrifugation. The liquid product dissolved in dichloromethane was collected, and the solid product was washed, collected, and dried in an oven at 80℃. The gaseous products generated by the reaction were detected online using gas chromatography. The liquid products were detected using gel permeation chromatography, nuclear magnetic resonance spectroscopy, and gas chromatography. The catalytic results are shown in the figure below. Figure 2 As shown in the figure, the mixed catalyst powder containing metal Ru / C exhibits the best catalytic performance.

[0058] Example 2

[0059] I. Preparation of catalyst materials, as detailed below:

[0060] Similar to the preparation of the catalyst material in Example 1, the difference lies in that Ru / C in Example 1 is replaced with Ru / CeO2, Ru / SiO2, or Ru / TiO2 metal-supported catalysts, while other conditions remain the same as in Example 1. Finally, reduced Ru / CeO2, Ru / SiO2, and Ru / TiO2 metal mixed catalyst powders are prepared.

[0061] (II) Application of Catalyst Materials

[0062] (1) Take 250 mg of the reduced Ru / C metal mixed catalyst powder obtained in Example 1 and the Ru / CeO2, Ru / SiO2 and Ru / TiO2 metal mixed catalyst powder obtained in this example, respectively. The reduced mixed catalyst powder corresponding to each metal accounts for 50 mg, and the calcined HZSM-5 zeolite accounts for 200 mg.

[0063] (2) Weigh 1g of low-density polyolefin powder (LDPE) and place it into a high-pressure reactor. See the schematic diagram of the 50ml reactor. Figure 1The reaction was carried out in air at a temperature of 280℃, a stirring rate of 400 rpm, and a reaction time of 12 h. After the reaction was completed, the remaining gas was collected using a gas bag. Subsequently, the liquid and solid products were dissolved and dispersed in dichloromethane, and separated by centrifugation. The liquid product dissolved in dichloromethane was collected, and the solid product was washed, collected, and dried in an oven at 80℃. The gaseous products generated by the reaction were detected online using gas chromatography. The liquid products were detected using gel permeation chromatography, nuclear magnetic resonance spectroscopy, and gas chromatography. The catalytic results are shown in the figure below. Figure 3 As shown in the figure, the metal Ru supported on the carbon-based support exhibits the best catalytic performance, which may be attributed to the fact that the carbon-based support is hydrophobic, and the plastic in the molten state is also hydrophobic, which is more conducive to mass transfer.

[0064] Example 3

[0065] Weigh 250 mg of the Ru-containing mixed catalyst powder prepared in Example 1, of which 50 mg is reduced Ru / C catalyst with a Ru loading of 5 wt.% and 200 mg is calcined HZSM-5 zeolite. Weigh 1 g of low-density polyolefin powder (LDPE) and place it in a high-pressure reactor. See the schematic diagram of the 50 ml reactor. Figure 1 A mixture of O2 and Ar in different proportions (O2 content of 5 vol%, 10 vol%, 20 vol%, and 50 vol%) was prepared. The reaction temperature was 280℃, the stirring rate was 400 rpm, and the reaction time was 12 h. After the reaction was completed, the remaining gas was collected using a gas bag. The liquid and solid products were then dissolved and dispersed in dichloromethane, separated by centrifugation. The liquid product dissolved in dichloromethane was collected, and the solid product was washed, collected, and dried in an oven at 80℃. The gaseous products generated by the reaction were detected online by gas chromatography. The liquid products were detected by gel permeation chromatography, nuclear magnetic resonance, and gas chromatography. The catalytic results are shown in the figure below. Figure 4 As shown in the figure, the best catalytic performance is exhibited when the O2 volume content is 20%.

[0066] Example 4

[0067] 250 mg of the mixed catalyst powder prepared in Example 1 was weighed, comprising 50 mg of Ru / C with a Ru loading of 5 wt.% and 200 mg of HZSM-5 zeolite. 1 g of low-density polyolefin powder (LDPE) was weighed and placed in a 50 ml reactor. The reactor was purged with air at least five times, and the reaction proceeded after the pressure was maintained at atmospheric pressure. The reaction temperatures were set at 220°C, 250°C, and 280°C, respectively, with a stirring rate of 400 rpm and a reaction time of 12 h. After the reaction was complete, the remaining gas was collected using a gas bag. The liquid and solid products were then dissolved and dispersed in dichloromethane, separated by centrifugation, and the liquid product dissolved in dichloromethane was collected. The solid product was washed, collected, and dried in an oven at 80°C. The gaseous products generated by the reaction were detected online using gas chromatography. The liquid products were detected using gel permeation chromatography, nuclear magnetic resonance spectroscopy, and gas chromatography. The catalytic results are shown in the figure. Figure 5 As shown in the figure, the oxygen-mediated polyolefin aromatization reaction system is most affected by time. At 250℃, a plastic conversion rate of over 80wt% can be achieved in 12 hours.

[0068] Example 5

[0069] This embodiment provides an experiment on the recovery and regeneration of mixed catalyst powder, as detailed below:

[0070] (1) Collect the mixed catalyst obtained after application in Example 1.

[0071] (2) The catalyst was washed five times with hot toluene at 180°C, and the mixed catalyst after the reaction was collected by centrifugation and dried in an oven at 80°C. Then it was calcined in a tube furnace at 300°C for 2 hours with a 5 Vol.% H2 / Ar mixed gas for catalyst regeneration.

[0072] (3) The catalyst typically loses 10 wt.% after the reaction. 25 mg of mixed catalyst was added, including 5 mg of reduced Ru / C metal catalyst and 20 mg of calcined HZSM-5 zeolite, for subsequent cycle stability testing. The catalyst and plastic were placed at the bottom of the reactor and purged with air at least five times, maintaining atmospheric pressure. The reaction temperature was 250℃, the stirring rate was 400 rpm, and the reaction time was 12 h. After the reaction, the remaining gas was collected using a gas bag; then, the liquid and solid products were dissolved and dispersed using dichloromethane, separated by centrifugation, and the liquid product dissolved in dichloromethane was collected. The solid product was washed, collected, and dried in an oven at 80℃. The gaseous products generated by the reaction were detected online by gas chromatography. The liquid products were detected by gel permeation chromatography, nuclear magnetic resonance, and gas chromatography. The stability test results are shown in […]. Figure 6As shown in the figure, the catalyst has extremely strong stability, and the liquid selectivity remains above 60 mol% after multiple cycles.

[0073] Example 6

[0074] Weigh 25g of the physically mixed catalyst prepared in Example 1, of which 5g is the reduced metal catalyst Ru / C with a Ru loading of 5wt.%, and 20g is the calcined HZSM-5 zeolite. Weigh 100g of low-density polyolefin powder (LDPE) and place it into a 2L reactor (see schematic diagram of 2L reactor). Figure 7 The catalyst and plastic were placed at the bottom of the reactor, and the mixture was purged with air at least five times while maintaining atmospheric pressure. The reaction temperature was 250°C, the stirring rate was 400 rpm, and the reaction time was 12 h. After the reaction was complete, the remaining gas was collected using a gas bag. Subsequently, the liquid and solid products were dissolved and dispersed in dichloromethane, and separated by centrifugation. The liquid product dissolved in dichloromethane was collected (product diagram shown). Figure 8 The solid products were washed and collected, then dried in an oven at 80°C. The gaseous products generated in the reaction were detected online using a gas chromatograph. The liquid products were detected using a gel permeation chromatograph, a nuclear magnetic resonance spectrometer, and a gas chromatograph.

[0075] Example 7

[0076] 2.5 g of the physically mixed catalyst prepared in Example 1 was weighed, including 0.5 g of reduced metal catalyst Ru / C with a Ru loading of 5 wt.% and 2 g of calcined HZSM-5 zeolite. 10 g of low-density polyolefin powder (LDPE) was weighed and placed in a 50 ml three-necked flask. The catalyst and plastic were placed at the bottom of the three-necked flask. The reaction temperature was 250 °C, the stirring rate was 200 rpm, and the reaction time was 4 h. After the reaction was completed, the liquid and solid products were dissolved and dispersed in dichloromethane, and separated by centrifugation. The liquid product dissolved in dichloromethane was collected, and the solid product was washed, collected, and dried in an oven at 80 °C. The gaseous products generated by the reaction were detected online by gas chromatography. The liquid products were detected by gel permeation chromatography, nuclear magnetic resonance, and gas chromatography. The catalytic test results are shown in [Figure number missing]. Figure 9 As shown in the figure, the reaction can still run in an open system under normal pressure and remains stable after multiple cycles.

[0077] in conclusion

[0078] The following results were obtained through analysis and calculation: Under the conditions of 280℃, 20% O2 (air) mixture ratio, reaction time of 12h, and stirring rate of 400rpm, the reduced metal catalyst Ru / C mixed catalyst with HZSM-5 exhibited the best activity and the highest selectivity for gasoline products, and showed good prospects for industrial application in large-scale experiments.

[0079] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A method for the efficient catalytic recovery of gasoline products from waste polyolefin plastics via oxygen-mediated processes, characterized in that, Includes the following steps: A metal-acid catalyst is mixed with waste polyolefin plastic and reacted in a mixture of oxygen-containing gas at normal pressure. The reaction liquid is then separated to obtain gasoline. The metal-acid catalyst includes a pretreated metal catalyst A and a pretreated solid acid catalyst B. The oxygen content in the mixed gas is 10-50% Vol%. The reaction temperature is 220-300℃; The metal-acid catalyst was prepared by the following method: Solid acid catalyst B and metal catalyst A are dried; The dried metal catalyst A was calcined in a reducing gas atmosphere to obtain the pretreated metal catalyst A. The dried solid acid catalyst B was calcined in air at 500-600℃ for 2-4 hours to obtain the pretreated solid acid catalyst B. The pretreated metal catalyst A and the pretreated solid acid catalyst B were mixed and ground to obtain the metal-acid catalyst. The solid acid catalyst B is selected from one or more of HZSM-5, USY, and SAPO-34; The metal in the metal catalyst A is one or more of Pd, Pt, Ru, Ni, Ir, and Co.

2. The method for efficient catalytic recovery of gasoline products from waste polyolefin plastics mediated by oxygen according to claim 1, characterized in that, The mixed gas also includes inactive gases, including nitrogen and / or argon.

3. The method for efficient catalytic recovery of gasoline products from waste polyolefin plastics mediated by oxygen according to claim 1, characterized in that, The waste polyolefin plastic is selected from one or more of low-density polyethylene plastic, high-density polyethylene plastic, and polypropylene plastic; The waste polyolefin plastic is in powder or block form, with a size of 1-5cm.

4. The method for efficient catalytic recovery of gasoline products from waste polyolefin plastics mediated by oxygen according to claim 1, characterized in that, The support for the metal catalyst A is one or more of C, CeO2, SiO2, and TiO2; The metal loading in the metal catalyst A is 1-10 wt.%.

5. The method for efficient catalytic recovery of gasoline products from waste polyolefin plastics mediated by oxygen according to claim 1, characterized in that, The reducing gas atmosphere includes hydrogen and inactive gases, wherein the concentration of hydrogen is 5-10 vol%, and the inactive gases are nitrogen and / or argon.

6. The method for efficient catalytic recovery of gasoline products from waste polyolefin plastics mediated by oxygen according to claim 1, characterized in that, The roasting temperature is 300℃ and the roasting time is 2-4 hours.

7. The method for efficient catalytic recovery of gasoline products from waste polyolefin plastics mediated by oxygen according to claim 1, characterized in that, The mass ratio of the pretreated metal catalyst A to the pretreated solid acid catalyst B is 1:(4-8).

8. The method for efficient catalytic recovery of gasoline products from waste polyolefin plastics mediated by oxygen according to claim 1, characterized in that, The mass ratio of the pretreated metal catalyst A, the pretreated solid acid catalyst B and the waste polyolefin plastic is 1:(4-8):(20-100).

9. The method for efficient catalytic recovery of gasoline products from waste polyolefin plastics mediated by oxygen according to claim 1, characterized in that, The reaction conditions are as follows: the reaction time is 1-12 hours, and the stirring rate is 200-1200 rpm.

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