Composite oxide carrier catalyst, and preparation method and application thereof

Abstract

The present application relates to a kind of composite oxide carrier catalyst and its preparation method and application, belong to high polymer material cracking and catalyst technical field.The composite oxide carrier catalyst of the present application includes carrier and active metal, the component of carrier includes ZrO2 And Al2O3, wherein the mass ratio of ZrO2 And Al2O3 It is (0.5-5):1;Active metal is at least one of Ba, Pt, Cu, Zn, Co, Ni, and the mass of active metal is 0.5-10% of the mass of catalyst.The present application provides a kind of composite catalyst by optimizing the proportion of carrier and active metal, with high catalytic cracking polyethylene efficiency, high liquid alkane yield, and good catalytic efficiency, has higher application value in the field of high polymer material cracking, plastic recycling.

Description

Technical Field

[0001] This invention relates to the field of polymer material pyrolysis and catalyst technology, and in particular to a composite oxide supported catalyst, its preparation method and application. Background Technology

[0002] Plastics are widely used in various industries worldwide, including food service, medical, and agriculture, due to their excellent physical and chemical properties such as lightweight, corrosion resistance, and good insulation. However, the disposal of plastic waste has become a global problem. Most plastics are difficult to degrade in the natural environment, and long-term landfill or incineration not only consumes a large amount of land resources but also causes serious environmental pollution. Therefore, finding effective methods for plastic waste disposal has become a key focus of current research.

[0003] Catalytic cracking technology has broad application prospects as a method for treating plastic waste. This technology converts waste plastics into liquid fuels, gases, and solid char through a chemical recycling process, providing high-value-added opportunities for waste plastic reuse. Compared with traditional mechanical treatment methods, catalytic cracking can more efficiently recover materials or energy, reduce environmental burden, and produce commercially valuable byproducts.

[0004] SiO2-Al2O3 is a traditional support for active metals in catalytic reactions. Compared to SiO2-Al2O3, the novel ZrO2-Al2O3 support exhibits stronger thermal stability and superior acidity control. Furthermore, the introduction of ZrO2 enhances the mechanical strength and resistance to carbon deposition of the support, effectively extending the catalyst's lifespan. Its high specific surface area and favorable pore structure further enhance its stability and catalytic efficiency under high-temperature conditions. However, the effectiveness of ZrO2-Al2O3-supported catalysts in catalytic cracking of plastics such as polyethylene has not yet been explored in existing technologies.

[0005] Therefore, developing a composite oxide-supported catalyst with good selectivity, high catalytic efficiency, and high liquid alkane yield for catalytic cracking of polyethylene plastics can yield high-value-added cracking products and has important application value in the fields of polymer material cracking and waste plastic recycling. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a composite oxide supported catalyst, its preparation method, and its applications. The composite oxide supported catalyst provided by this invention exhibits high catalytic efficiency and high selectivity for liquid hydrocarbon products during polyethylene cracking, and has significant application value in the recycling of polyethylene plastics.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0008] In a first aspect, the present invention provides a composite oxide supported catalyst, comprising a support and an active metal, wherein the support comprises ZrO2 and Al2O3, and the mass ratio of ZrO2 to Al2O3 is (0.5-5):1; the active metal is at least one selected from Ba, Pt, Cu, Zn, Co, and Ni, and the mass of the active metal is 0.5-10% of the mass of the composite oxide supported catalyst.

[0009] This invention employs a combination of ZrO2 and Al2O3 as the catalyst support. By introducing the oxide ZrO2, the mechanical strength and thermal stability of the support are significantly improved compared to traditional supports. This allows the catalyst to maintain the integrity and dispersion of active sites for extended periods under high-temperature reaction conditions, preventing the aggregation or loss of active metals at high temperatures. Furthermore, the doping of active metals promotes C / C bond breaking and hydrogen adsorption, thereby increasing the yield of light hydrocarbons and liquid fuels and regulating acid-base sites. This optimizes the product distribution of the cracking reaction and reduces coke formation. The synergistic effect of the active metals in the catalyst and the ZrO2-Al2O3 support provides suitable active sites, enabling effective cracking of polyethylene molecular chains on the catalyst surface, particularly in hydrocracking reactions, thus increasing the yield of light hydrocarbons.

[0010] The composite oxide supported catalyst provided by this invention exhibits significant advantages in the catalytic cracking reaction of polyethylene. The optimal mass ratio of ZrO2 and Al2O3 results in a distribution of strongly acidic sites on the support. These sites contribute to improving the C / C bond breaking efficiency during polyethylene cracking, significantly enhancing reaction activity and product selectivity. Conversely, when the oxide ratio in the support is unsuitable, the catalyst's catalytic efficiency decreases significantly, and its selectivity for liquid alkanes diminishes.

[0011] The active metal defined in this invention, within its loading range, can neutralize some acidic sites and adjust the acidity of the ZrO2-Al2O3 support, preventing excessive acidity from causing excessive cracking of polyethylene and generating too many gaseous products. Appropriate acidity control helps improve the selectivity of liquid hydrocarbons, making the catalytic cracking reaction more targeted and generating high-value-added fuel products. When the loading is too high or too low, it will lead to a significant decrease in the catalytic efficiency of the composite catalyst, excessive gaseous products, and a decrease in the yield of liquid alkanes, which is detrimental to the recovery and reuse of liquid alkanes.

[0012] The composite oxide supported catalyst of this invention exhibits a catalytic efficiency of over 40% and a yield of over 20% for liquid hydrocarbons (C5-C21) in the polyethylene cracking reaction, demonstrating excellent plastic cracking performance, superior thermal stability, strong resistance to carbon deposition, and high selectivity for liquid hydrocarbon products. It is also more conducive to generating high-value-added fuel products and has high application value in the recycling and reuse of polyethylene plastics.

[0013] Preferably, the mass ratio of ZrO2 to Al2O3 is (2-5):1.

[0014] More preferably, the mass ratio of ZrO2 to Al2O3 is 2:1.

[0015] Preferably, the active metal is at least one of Ba and Pt.

[0016] More preferably, the active metal is Ba.

[0017] The present invention selects the most preferred active metal Ba, which interacts with the ZrO2-Al2O3 support to provide suitable active sites, enabling the polyethylene molecular chain to undergo more effective cracking reaction on the catalyst surface. In particular, in the hydrocracking reaction, it can further improve the yield of light hydrocarbons (C5-C21 liquid alkanes).

[0018] Preferably, the mass of the active metal is 1-5% of the mass of the composite oxide supported catalyst.

[0019] More preferably, the mass of the active metal is 2.5-5% of the mass of the composite oxide supported catalyst.

[0020] Within the preferred carrier ratio, active metal and active metal dosage range of this invention, the composite oxide supported catalyst can achieve a catalytic efficiency of up to 87.8% and a yield of up to 65.3% for liquid alkanes (C5-C21) in the polyethylene cracking reaction, demonstrating superior catalytic performance and high added value of the recovered products.

[0021] Secondly, the present invention provides a method for preparing the above-mentioned composite oxide supported catalyst, comprising the following steps:

[0022] (1) Preparation of carrier: Mix zirconium oxychloride solution and aluminum nitrate solution, add surfactant, then adjust pH value to 8-9, stir until precipitate is formed, separate the precipitate, wash, dry and calcinate to obtain carrier powder;

[0023] (2) Loading active metal: The carrier powder is dispersed in water, a soluble active metal salt is added, the mixture is stirred and adsorbed, the solid is separated, washed and dried, and then calcined in an inert atmosphere to obtain the composite oxide carrier catalyst.

[0024] The method for preparing the composite oxide supported catalyst provided by the present invention first synthesizes ZrO2-Al2O3 molecular sieve material by co-precipitation, which is ZrO2-Al2O3 support. Then, the active metal is uniformly loaded onto the support by impregnation and calcined at high temperature in an inert atmosphere to form a composite catalyst with good acid-base regulation ability.

[0025] Preferably, the inert atmosphere is an argon atmosphere.

[0026] Preferably, the surfactant is at least one selected from cetyltrimethylammonium bromide, polyvinylpyrrolidone, triblock copolymer, polyethylene glycol, and sodium dodecyl sulfate.

[0027] Preferably, the roasting temperature is 400-800℃ and the roasting time is 4-8 hours.

[0028] More preferably, the roasting temperature is 550°C and the roasting time is 4 hours.

[0029] Thirdly, the present invention provides the application of the above-mentioned composite oxide supported catalyst in the polyethylene cracking reaction.

[0030] Preferably, the application includes the following steps: mixing the composite oxide supported catalyst with polyethylene and heating it to 300-500°C in a hydrogen atmosphere to react.

[0031] Preferably, the mass ratio of the composite oxide supported catalyst to the polyethylene is 1:(8-12).

[0032] Preferably, in the hydrogen atmosphere, the flow rate of hydrogen is 25-100 mL / min; the heating is to raise the temperature from room temperature to 300-500°C at a rate of 10°C / min, and the reaction time is 3-5 hours.

[0033] More preferably, the reaction temperature is 350-400℃.

[0034] In the hydrocracking reaction of polyethylene, the combined effect of the ZrO2-Al2O3 support and the active metal in the composite oxide supported catalyst of this invention significantly enhances the activity and selectivity of the catalyst. Especially at a relatively low temperature of 350-400℃, it can efficiently catalyze the cracking of polyethylene to generate liquid hydrocarbons with high added value.

[0035] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0036] This invention provides a composite oxide supported catalyst. By optimizing the ZrO2-Al2O3 support and its ratio, as well as the type and loading of the active metal, it exhibits strong thermal stability and superior acidity control capability. The introduced ZrO2 can improve the mechanical strength and anti-carbon deposition ability of the support, extending the catalyst's service life. Its high specific surface area and good pore structure further enhance its stability and catalytic efficiency under high-temperature conditions. It exhibits excellent selectivity and reaction efficiency in the catalytic cracking of polyethylene, significantly improving the yield of light hydrocarbons (C5-C21 liquid alkanes), which is more conducive to the production of high-value-added fuel products. It has high application value in the recycling and reuse of polyethylene plastics. Attached Figure Description

[0037] Figure 1 The XRD patterns of the composite oxide supported catalysts in Examples 1-3 are shown below.

[0038] Figure 2 Here is a SEM image of the composite oxide supported catalyst of Example 2;

[0039] Figure 3 The graph shows the catalytic performance of the composite oxide supported catalyst in Example 2 at different reaction temperatures in the polyethylene cracking reaction.

[0040] Figure 4 The following is a graph showing the catalytic performance of the composite oxide supported catalyst for polyethylene cracking under different active metals in the embodiments.

[0041] Figure 5 The graph shows the catalytic performance of the composite oxide supported catalyst for polyethylene cracking under different loadings of active metals in the example.

[0042] Figure 6 The graphs show the catalytic performance of the composite oxide supported catalysts for polyethylene cracking under different ZrO2-Al2O3 ratios in the examples and comparative examples.

[0043] Figure 7 The graph shows the performance of a composite oxide-supported catalyst with a conventional support in catalyzing the cracking reaction of polyethylene. Detailed Implementation

[0044] To better illustrate the purpose, technical solution, and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments. Unless otherwise specified, the experimental methods used in the following embodiments are conventional methods; the materials and reagents used, unless otherwise specified, are commercially available reagents and materials.

[0045] Example 1

[0046] One embodiment of the composite oxide supported catalyst of the present invention is a composite catalyst in which Ba is supported on a ZrO2-Al2O3 support, wherein the loading of active metal Ba is 5% of the total mass of the catalyst, and the mass ratio of ZrO2 to Al2O3 in the support is 2:1.

[0047] The preparation method of the composite oxide supported catalyst described in this embodiment is as follows:

[0048] (1) Preparation of carrier:

[0049] Zirconium oxychloride (ZrOCl2·8H2O) and aluminum nitrate (Al(NO3)3·9H2O) were dissolved in deionized water to prepare 0.1M solutions of zirconium oxychloride and aluminum nitrate, respectively.

[0050] Take 10.8 ml of 0.1 M zirconium oxychloride solution and 13.1 ml of 0.1 M aluminum nitrate solution respectively, mix and stir well, add 50 mg of PEG to the mixed solution, and slowly add 1 M ammonia solution dropwise while stirring to adjust the pH value to 8-9. Then continue stirring at room temperature for 2 hours to promote precipitation.

[0051] The obtained precipitate was separated by vacuum filtration, washed repeatedly with deionized water until the filtrate was nearly neutral, dried at 80°C for 12 hours, ground into powder, and then calcined at 550°C for 4 hours to obtain ZrO2-Al2O3 support powder.

[0052] (2) Loaded with active metals:

[0053] Weigh 1g of ZrO2-Al2O3 carrier powder prepared in step (1), disperse it in 200ml of deionized water, measure 3.84ml of 0.1M BaCl2 solution and slowly add it dropwise to the ZrO2-Al2O3 suspension while stirring.

[0054] Continue stirring for 12 hours to ensure Ba 2+ The solid was uniformly distributed and adsorbed onto the surface of ZrO2-Al2O3. The obtained solid was separated by vacuum filtration, washed with deionized water until the filtrate was colorless, and then dried at 80°C for 12 hours. The obtained solid was ground into powder and finally reduced at 400°C in an argon atmosphere for 4 hours to obtain the composite oxide supported catalyst.

[0055] The XRD pattern of the composite oxide supported catalyst 5% Ba / ZrO2-Al2O3 prepared in this invention is shown in the figure. Figure 1 As shown.

[0056] Example 2

[0057] One embodiment of the composite oxide supported catalyst of the present invention is a composite catalyst in which Ba is supported on a ZrO2-Al2O3 support, wherein the loading of active metal Ba is 2.5% of the total mass of the catalyst, and the mass ratio of ZrO2 to Al2O3 in the support is 2:1.

[0058] The difference between the preparation method of the composite oxide supported catalyst in this embodiment and that in Example 1 is that the amount of BaCl2 solution added in step (2) is 1.87 ml.

[0059] The XRD pattern of the composite oxide supported catalyst 2.5% Ba / ZrO2-Al2O3 prepared by this invention is shown in the figure. Figure 1 As shown, its scanning electron microscope image is as follows. Figure 2 .

[0060] Example 3

[0061] One embodiment of the composite oxide supported catalyst of the present invention is a composite catalyst in which Ba is supported on a ZrO2-Al2O3 support, wherein the loading of active metal Ba is 1.25% of the total mass of the catalyst, and the mass ratio of ZrO2 to Al2O3 in the support is 2:1.

[0062] The preparation method of the composite oxide supported catalyst described in this embodiment differs from that in Example 1 in that the amount of BaCl2 solution added in step (2) is 0.92 ml.

[0063] The XRD pattern of the composite oxide supported catalyst 1.25% Ba / ZrO2-Al2O3 prepared by this invention is shown in the figure. Figure 1 As shown.

[0064] Example 4

[0065] One embodiment of the composite oxide supported catalyst of the present invention is a composite catalyst in which Ba is supported on a ZrO2-Al2O3 support, wherein the loading of active metal Ba is 2.5% of the total mass of the catalyst, and the mass ratio of ZrO2 to Al2O3 in the support is 5:1.

[0066] The preparation method of the composite oxide supported catalyst described in this embodiment differs from that in Example 2 in that the amount of zirconium oxychloride solution used in step (1) is 27 ml.

[0067] Example 5

[0068] One embodiment of the composite oxide supported catalyst of the present invention is a composite catalyst in which Ba is supported on a ZrO2-Al2O3 support, wherein the loading of active metal Ba is 2.5% of the total mass of the catalyst, and the mass ratio of ZrO2 to Al2O3 in the support is 0.5:1.

[0069] The difference between the preparation method of the composite oxide supported catalyst in this embodiment and that in Example 2 is that the amount of zirconium oxychloride solution used in step (1) is 2.7 ml.

[0070] Example 6

[0071] One embodiment of the composite oxide supported catalyst of the present invention is a composite catalyst in which Pt is supported on a ZrO2-Al2O3 support, wherein the loading of active metal Pt is 2.5% of the total mass of the catalyst, and the mass ratio of ZrO2 to Al2O3 in the support is 2:1.

[0072] The preparation method of the composite oxide supported catalyst in this embodiment differs from that in Example 2 in that the barium chloride solution used is replaced with 1.32 ml of PtCl4 solution of the same concentration.

[0073] Example 7

[0074] One embodiment of the composite oxide supported catalyst of the present invention is a composite catalyst in which Zn is supported on a ZrO2-Al2O3 support, wherein the loading of active metal Zn is 2.5% of the total mass of the catalyst, and the mass ratio of ZrO2 to Al2O3 in the support is 2:1.

[0075] The preparation method of the composite oxide supported catalyst in this embodiment differs from that in Example 2 in that the barium chloride solution used is replaced with 3.95 ml of ZnCl2 solution of the same concentration.

[0076] Comparative Example 1

[0077] A composite catalyst with Ba supported on a SiO2-Al2O3 support is disclosed, wherein the loading of active metal Ba is 2.5% of the total mass of the catalyst, and the mass ratio of SiO2 to Al2O3 in the support is 5:1. The preparation method differs from that in Example 2 only in that the zirconium oxychloride solution used in step (1) is replaced with 55.46 ml of sodium silicate (Na2SiO3) solution of the same concentration.

[0078] Comparative Example 2

[0079] A composite catalyst with Ba supported on a SiO2-Al2O3 support is disclosed, wherein the loading of active metal Ba is 2.5% of the total mass of the catalyst, and the mass ratio of SiO2 to Al2O3 in the support is 2:1. The preparation method differs from that in Example 2 only in that the zirconium oxychloride solution used in step (1) is replaced with 22.18 ml of sodium silicate (Na2SiO3) solution of the same concentration.

[0080] Comparative Example 3

[0081] A composite catalyst with Ba supported on a SiO2-Al2O3 support is disclosed, wherein the loading of active metal Ba is 2.5% of the total mass of the catalyst, and the mass ratio of SiO2 to Al2O3 in the support is 0.5:1. The preparation method differs from Example 2 only in that the zirconium oxychloride solution used in step (1) is replaced with 5.55 ml of sodium silicate (Na2SiO3) solution of the same concentration.

[0082] Comparative Example 4

[0083] A composite catalyst with Ba supported on a ZrO2-Al2O3 support is disclosed, wherein the loading of active metal Ba is 2.5% of the total mass of the catalyst, and the mass ratio of ZrO2 to Al2O3 in the support is 10:1. The preparation method differs from that in Example 2 in that the amount of zirconium oxychloride solution used in step (1) is 54 ml.

[0084] Comparative Example 5

[0085] A composite catalyst with Ba supported on a ZrO2-Al2O3 support is disclosed, wherein the loading of active metal Ba is 2.5% of the total mass of the catalyst, and the mass ratio of ZrO2 to Al2O3 in the support is 0.25:1. The preparation method differs from that in Example 2 in that the amount of zirconium oxychloride solution used in step (1) is 1.35 ml.

[0086] Example of effect 1

[0087] To investigate the reaction temperature of the composite oxide supported catalyst provided by this invention in the catalytic cracking of polyethylene, the composite oxide supported catalyst in Example 2 was subjected to the following catalytic experiments:

[0088] Weigh 0.5g of the catalyst from Example 2 and mix it evenly with 5g of polyethylene. Add the mixture to a reaction vessel and place the vessel in a fixed-bed reactor. First, purge with argon gas for 1 hour, then purge with hydrogen gas for another 1 hour at a flow rate of 100ml / min. After purging, raise the temperature to 300℃, 350℃, and 400℃ at a rate of 10℃ / min, and react for 4 hours. After the reaction, collect and analyze the gaseous, liquid, and solid residues in the reaction products to determine the catalyst's cracking efficiency and product distribution. The results are shown in Table 1 below, and the comparative analysis of catalytic performance is shown in the following figure. Figure 3 .

[0089] From Table 1 and Figure 3 It is known that: when the composite oxide supported catalyst of the present invention is heated to 350°C to carry out the cracking reaction of polyethylene, the catalytic efficiency is the highest and the yield of C5-C21 liquid alkanes is relatively high, and the overall catalytic effect is the best. Decreasing or increasing the temperature will lead to a decrease in catalytic efficiency, and the yield of liquid alkanes may decrease significantly while the yield of products increases.

[0090] Table 1. Catalytic performance of the catalyst in Example 2 at different reaction temperatures for polyethylene cracking.

[0091] reaction temperature 300℃ 350℃ 400℃ Catalytic efficiency 65.30％ 87.80％ 73.60％ C5-C21 liquid alkane yield 33.80％ 65.30％ 38.90％

[0092] Example 2

[0093] To further investigate the specific application effect of the composite oxide supported catalyst provided by this invention in the catalytic cracking of polyethylene, the following catalytic experiments were conducted on the catalysts in the examples and comparative examples:

[0094] Weigh 0.5g of the catalyst from each example and comparative example, mix it evenly with 5g of polyethylene, and add it to a reaction vessel. Place the reaction vessel in a fixed-bed reactor. First, purge with argon gas for 1 hour, then purge with hydrogen gas for another 1 hour at a flow rate of 100ml / min. After purging, raise the temperature to 350℃ at a rate of 10℃ / min and react for 4 hours. After the reaction, collect and analyze the gaseous, liquid, and solid residues in the reaction products to determine the catalyst's cracking efficiency and product distribution. The results are shown in Table 2 below, and the comparative analysis of catalytic performance is shown in the following figure. Figure 4-7 Therefore, we can conclude that:

[0095] (1) Comparing Table 2, in Examples 1-7, the composite oxide support catalyst with specific ZrO2-Al2O3 support and support ratio provided by the present invention has better catalytic cracking efficiency for polyethylene, which is better than the catalysts in the comparative examples with SiO2-Al2O3 support or unsuitable ZrO2-Al2O3 ratio in the support; among them, the composite oxide support catalyst in Example 2 has the best catalytic effect on polyethylene under the selection of active metal and support ratio, with a catalytic efficiency of 87.80% and a liquid alkane (C5-C21) yield of up to 65.30%, which can achieve efficient catalytic cracking of polyethylene and high yield of high value-added fuel products;

[0096] (2) By Figure 4 A comparison of the catalytic performance shows that different active metal selections affect the catalytic cracking effect of the composite oxide supported catalyst of this invention on polyethylene. Under otherwise unchanged conditions, the catalytic efficiency and the yield of C5-C21 liquid alkanes are Ba > Pt > Zn. Figure 5 The comparison of catalytic performance shows that different active metal loadings also have a certain impact on the catalytic effect of the composite oxide supported catalyst of the present invention. The optimal loading of active metal Ba is 2.5%. Loadings higher or lower than this will reduce the catalytic efficiency and significantly reduce the yield of C5-C21 liquid alkanes.

[0097] (3) By Figure 6 A comparison of catalytic performance shows that when the mass ratio of ZrO2 to Al2O3 in the support is within the range defined in this invention, the catalytic efficiency can reach over 55%, and the yield of C5-C21 liquid alkanes is over 35%, demonstrating a significantly better catalytic cracking effect than comparative examples 3 and 4, which had unsuitable ratios. Figure 7 The catalytic performance results show that, under the same conditions, the catalytic effect of different support ratios is significantly worse when using the traditional SiO2-Al2O3 support.

[0098] In summary, this invention uses a combination of ZrO2 and Al2O3 as the catalyst support. By introducing the oxide ZrO2, the mechanical strength and thermal stability of the support are significantly improved compared to traditional supports. This allows the catalyst to maintain the integrity and dispersion of active sites for a long time under high-temperature reaction conditions, avoiding the aggregation or loss of active metals under high-temperature conditions and significantly improving the catalytic effect. Furthermore, the preferred active metal doping promotes C / C bond breaking and hydrogen adsorption, thereby increasing the yield of light hydrocarbons and liquid fuels, regulating acidity and alkalinity sites, optimizing the product distribution of the cracking reaction, increasing the yield of C5-C21 liquid alkanes, and realizing the high-net-value product recovery and utilization of polyethylene cracking, which has high practical value.

[0099] Table 2 shows the performance results of the catalysts used in the examples and comparative examples for catalytic polyethylene cracking.

[0100]

[0101]

[0102] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A composite oxide supported catalyst, characterized in that, The catalyst comprises a support and an active metal. The support consists of ZrO2 and Al2O3 in a mass ratio of 2:

1. The active metal is Ba, and its mass is 2.5% of the mass of the composite oxide support catalyst.

2. The method for preparing the composite oxide supported catalyst as described in claim 1, characterized in that, Includes the following steps: (1) Preparation of carrier: Mix zirconium oxychloride solution and aluminum nitrate solution, add surfactant, then adjust pH value to 8-9, stir until precipitate is formed, separate the precipitate, wash, dry and calcine to obtain carrier powder; (2) Loading active metal: The carrier powder is dispersed in water, a soluble active metal salt is added, stirred and adsorbed, the solid is separated, washed and dried, and then calcined in an inert atmosphere to obtain the composite oxide carrier catalyst.

3. The preparation method of the composite oxide supported catalyst as described in claim 2, characterized in that, The surfactant is at least one of cetyltrimethylammonium bromide, polyvinylpyrrolidone, triblock copolymer, polyethylene glycol, and sodium dodecyl sulfate.

4. The preparation method of the composite oxide supported catalyst as described in claim 2, characterized in that, The roasting temperature is 400-800℃, and the roasting time is 4-8 hours.

5. The application of the composite oxide supported catalyst as described in claim 1 in the polyethylene cracking reaction.

6. The application of the composite oxide supported catalyst as described in claim 5 in the polyethylene cracking reaction, characterized in that, The application The process includes the following steps: mixing the composite oxide supported catalyst with polyethylene and heating it to 300-500°C in a hydrogen atmosphere to react.

7. The application of the composite oxide supported catalyst as described in claim 6 in the polyethylene cracking reaction, characterized in that, The mass ratio of the composite oxide supported catalyst to the polyethylene is 1:(8-12).

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