A CuO / TiO2 photothermal catalyst, its preparation method and application, and a method for photothermal catalytic degradation of plastics.

Abstract

This invention relates to a CuO / TiO2 photothermal catalyst, its preparation method and application, and a method for photothermal catalytic degradation of plastics. The catalyst is prepared using an impregnation-calcination method. The preparation process involves uniformly mixing a soluble copper salt precursor solution with a titanium dioxide support, followed by ultrasonication, settling, drying, and calcination to obtain the CuO / TiO2 catalyst. Plastic is then mixed with the CuO / TiO2 photothermal catalyst and placed in a reactor. A photothermal catalytic reaction is carried out under light and heating conditions. The reactants are collected to obtain liquid fuel oil; the liquid fuel oil is a gasoline fraction C5-C. 12 Aviation fuel fraction C8-C 16 Or diesel fraction C 10 -C 23 One or more of the following. Compared with the prior art, the present invention has the advantages of achieving efficient catalytic degradation of polyethylene plastics under photothermal synergistic conditions and directional conversion to liquid fuel.

Description

Technical Field

[0001] This invention relates to the field of plastic resource recycling technology, and in particular to a CuO / TiO2 photothermal catalyst, its preparation method and application, and a method for photothermal catalytic degradation of plastics. Background Technology

[0002] Waste plastics are difficult to degrade in the natural environment, and existing treatment technologies have many limitations. Landfill disposal consumes land resources and may cause soil and groundwater pollution, while incineration easily produces toxic and harmful gases such as dioxins; both pose a risk of secondary pollution. Mechanical recycling (physical recycling), although relatively common, is usually accompanied by a decline in material properties, facing the dilemma of "degraded recycling," and lacking economic viability and sustainability. Therefore, developing chemical recycling technologies that can efficiently convert waste plastics into high-value chemicals or fuels is crucial for achieving a circular economy for plastics.

[0003] Among various chemical recycling pathways, catalytic cracking, capable of breaking down plastic polymer chains under relatively mild conditions and controlling the reaction pathway through catalysts, is a promising technological direction. However, this technology still faces significant challenges in practical applications. Traditional solid acid catalysts or noble metal catalysts generally suffer from problems such as easy coking and deactivation, easy sintering of metal components, and insufficient control over the carbon-carbon bond breaking sites. This directly leads to a broad distribution of reaction products, low selectivity, and difficulty in directly and directionally obtaining specific fuel components with high economic value (such as aviation kerosene fraction C8-C). 16 Diesel fraction C 10 -C 23 ).

[0004] In recent years, photothermal synergistic catalysis strategies have attracted attention due to their potential to drive reactions with lower overall energy consumption. However, their application in the field of plastic resource utilization remains significantly limited. Most current research focuses either on the complete mineralization of plastics or only yields mixtures with a wide range of carbon numbers. A technological system capable of efficiently depolymerizing complex plastic polymers and precisely converting them into specific high-value fuels is still lacking. The core bottleneck lies in the fact that existing catalysts, under the synergistic effect of light and heat, lack the ability to precisely control the breaking of carbon-carbon bonds and the recombination pathways of intermediate products in plastic polymers, making it difficult to lock the products within the target carbon number range.

[0005] Titanium dioxide (TiO2)-based catalysts have been widely studied due to their low cost and stable chemical properties. However, they suffer from inherent drawbacks such as rapid recombination of photogenerated carriers and a narrow range of solar spectrum utilization, and lack specific active sites for the directional conversion of plastic pyrolysis products. Constructing heterojunction composite materials such as CuO / TiO2 can improve their photocatalytic performance to some extent. However, under synergistic photothermal conditions, how to simultaneously achieve efficient depolymerization of waste plastics and precise control of the carbon number distribution of the products to directly obtain highly selective target fuel fractions remains a key technical challenge that has yet to be overcome in the practical application of this technology.

[0006] Patent publication number CN104707605A discloses a method for preparing a Cu2O / TiO2 composite photothermal catalyst. This method includes the following steps: preparation of a tetrabutyl titanate hydrolysis buffer solution; preparation of nano-TiO2 catalyst powder; and preparation of the Cu2O / TiO2 composite photothermal catalyst, resulting in a Cu2O / TiO2 composite photothermal catalyst with a photothermal synergistic catalytic effect. This catalyst, by constructing a heterojunction structure between Cu2O and TiO2, improves photocatalytic performance to a certain extent. Its photothermal synergistic effect is 30-40% higher than that of a single photocatalytic effect and 50-60% higher than that of a single thermal catalytic effect. However, the disclosed Cu2O / TiO2 composite photothermal catalyst is mainly applied to the catalytic oxidation degradation of volatile organic compounds (VOCs), such as the removal of pollutants like toluene and formaldehyde. It does not involve the chemical recycling of waste plastics, nor does it possess the ability to directionally convert waste plastics into fuel fractions within a specific carbon number range. Summary of the Invention

[0007] The purpose of this invention is to overcome the shortcomings of the existing technology, such as low product selectivity, wide carbon number distribution, and difficulty in obtaining high-value liquid fuel fractions in the photothermal catalytic degradation of waste plastics, and to provide a CuO / TiO2 photothermal catalyst, its preparation method and application, and a photothermal catalytic degradation method for plastics, so as to achieve efficient catalytic degradation of polyethylene plastics under photothermal synergistic conditions and directional conversion into liquid fuels.

[0008] The objective of this invention can be achieved through the following technical solutions: One of the technical solutions of the present invention is to provide a method for preparing CuO / TiO2 photothermal catalyst, which is prepared by impregnation-calcination method. The preparation process is as follows: a soluble copper salt precursor solution is uniformly mixed with a titanium dioxide support, followed by ultrasonication, standing, drying, and calcination to obtain the CuO / TiO2 catalyst.

[0009] Further, the soluble copper salt in the soluble copper salt precursor solution is one or more of copper nitrate, copper acetate, or copper chloride, preferably copper nitrate; its concentration is 0.01~0.5 mol / L, preferably 0.026~0.39 mol / L; The titanium dioxide support is anatase, rutile, or a mixture of both.

[0010] Furthermore, the mixed crystal form of anatase and rutile is nanoscale titanium dioxide, and the mass ratio of the two is 3 to 5:1, preferably 4:1. When the mass ratio is 4:1, the titanium dioxide carrier is usually referred to as type P25.

[0011] Furthermore, the CuO loading in the CuO / TiO2 catalyst is 1wt%~15wt%, preferably 5wt%~15wt%.

[0012] Furthermore, the duration of the ultrasound is 0.5 to 3 hours; The drying temperature is 100~140℃, and the time is 6~48h; The calcination atmosphere is air or an oxygen-containing atmosphere, the calcination temperature is 300~500℃, preferably 350~450℃, and the heating rate is 0.5~5℃ / min, preferably 0.5~2℃ / min.

[0013] The second technical solution of the present invention is a CuO / TiO2 photothermal catalyst, which is prepared by the preparation method described above.

[0014] The third technical solution of the present invention is to provide an application of a CuO / TiO2 photothermal catalyst, wherein the CuO / TiO2 photothermal catalyst is used for the photothermal catalytic degradation of plastics to obtain liquid fuel; The liquid fuel is aviation fuel fraction C8-C. 16 Or diesel fraction C 10 -C 23 One or more of them.

[0015] Furthermore, the plastic includes one or more of low-density polyethylene (LDPE), high-density polyethylene (HDPE), polypropylene (PP), polystyrene (PS), polyethylene terephthalate (PET), and polylactic acid (PLA).

[0016] The fourth technical solution of the present invention provides a method for photothermal catalytic degradation of plastics, comprising the following steps: S1. Mix the plastic with the CuO / TiO2 photothermal catalyst as described in claim 5 and place it in a reactor; S2. Photothermal catalytic reaction is carried out under light and heating conditions; S3. Collect the reactants to obtain liquid fuel oil; The liquid fuel is aviation fuel fraction C8-C. 16 Or diesel fraction C 10 -C 23 One or more of them.

[0017] Further, in step S1, the mass ratio of the plastic to the CuO / TiO2 photothermal catalyst is 1~5:1, preferably 1.5~2.5:1; In step S2, the illumination is provided by simulating a solar light source, and the heating temperature is 200~350℃, preferably 240~320℃. In step S2, the photothermal catalytic reaction is carried out in an inert atmosphere or vacuum environment for a reaction time of 2 to 20 hours, preferably 4 to 12 hours.

[0018] Furthermore, the simulated solar light source is provided by a xenon lamp with a power of 200~1000W, and is focused by a Fresnel lens to enhance the photothermal effect.

[0019] Further, in step S3, the liquid fuel is preferably an aviation fuel fraction C8-C. 16 .

[0020] Further, in step S3, the aviation fuel fraction C8-C 16 The selectivity is 50%~90%, and the diesel fraction C 10 -C 23 The selectivity is 65%~85%.

[0021] Furthermore, in step S2, the photothermal catalytic reaction is a photothermal synergistic catalytic process, that is, the reaction temperature is mainly provided by the thermal energy converted from light energy, and the light irradiation simultaneously excites and generates photogenerated carriers to participate in the reaction. This process is significantly different from single thermal catalysis or photocatalysis.

[0022] Compared with the prior art, the present invention has the following advantages: (1) The present invention uses inexpensive titanium dioxide and copper salt as raw materials and adopts conventional impregnation-calcination process to prepare CuO / TiO2 photothermal catalyst. The process is simple, reproducible, low cost, easy to scale up production, and has high industrial application value. (2) The CuO / TiO2 photothermal catalyst prepared in this invention has good light absorption and photothermal conversion capabilities. Under simulated sunlight irradiation, it can achieve synergistic catalysis of light energy and heat energy, significantly reduce the reaction activation energy, and achieve efficient depolymerization of polyethylene under mild conditions of 280℃, which greatly reduces energy consumption compared with traditional pure pyrolysis (>450℃). (3) The method of the present invention has a strong ability to control the selectivity of the product. Under the preferred conditions (CuO loading 10 wt%, reaction temperature 280℃, reaction time 6 h), the liquid product contains high-value-added C8-C 16 The relative content of aviation fuel components can reach up to 86.06%, and a high proportion of C can be obtained through simultaneous control. 10 -C 23 The diesel component enables the targeted conversion of waste plastics into specific high-value fuels; (4) The entire reaction process of this invention is driven by light as the main driving force, without the need for external hydrogen or organic solvents. The catalyst is easy to separate and recover, the process is clean and environmentally friendly, and meets the requirements of green chemistry and sustainable development.

[0023] (5) This invention is essentially the result of the synergistic effect of photocatalysis and thermocatalysis. Its core lies in the directional transfer of photogenerated charges between the TiO2 and CuO nanoclusters interface under light excitation. Photogenerated electrons are transferred from the conduction band of TiO2 to the CuO clusters. After the CuO nanoclusters adsorb the long LDPE chain, the active sites capture hydrogen atoms from the polymer chain, promoting the breaking of C / C and CH bonds, and driving the breaking of the polyethylene chain. The role of light is to drive the charge transfer, and the role of heat is to maintain the melting and diffusion of the substrate and supply the activation energy required for the cleavage of C / C bonds. The synergistic effect of the interface between CuO nanoclusters and TiO2 can precisely guide the isomerization and recombination pathways of intermediate products, inhibit the excessive cleavage and excessive condensation of carbon chains to form coke, thereby firmly locking the carbon number distribution of the product to C8-C. 16 and C 10 -C 23 The target high-value fraction range has been optimized for targeted conversion, enabling LDPE to be effectively converted into high-value fuel resources. Attached Figure Description

[0024] Figure 1 Transmission electron microscopy image of CuO / TiO2 photothermal catalyst with 10% CuO loading as shown in Example 3; Figure 2 X-ray diffraction patterns of CuO / TiO2 photothermal catalysts with different CuO loadings; Figure 3 A simplified diagram of the photothermal catalytic reaction apparatus for the catalytic degradation of polyethylene plastics to prepare liquid fuel oil according to the present invention; Figure 4 The carbon atom number distribution of the products after plastic degradation by CuO / TiO2 photothermal catalysts with different CuO loadings; Figure 5 The carbon atom number distribution of the products after degradation of plastics by CuO / TiO2 photothermal catalyst at different reaction temperatures is shown. Figure 6The carbon atom distribution of the products after degradation of plastics by CuO / TiO2 photothermal catalyst at different reaction times is shown. Figure 7 The figure shows the effect of CuO / TiO2 photothermal catalyst on the selectivity of aviation fuel after eight consecutive cycles of plastic degradation.

[0025] Explanation of markings in the diagram: 1-CuO / TiO2 photothermal catalyst, 11-TiO2 support, 12-CuO active component; 2-Plastic; 3-Photothermal catalytic reaction device, 31-Photochemical quartz reactor, 32-Ventilation port, 33-Thermocouple, 34-High-transparency quartz window, 35-Fresnel lens, 36-Xenon lamp, 37-Platform for carrying materials; 4-GC-MS instrument. Detailed Implementation

[0026] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. These embodiments are implemented based on the technical solution of the present invention, providing detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments. All other embodiments obtained by those skilled in the art based on the given embodiments without creative effort are within the scope of protection of this application.

[0027] Unless otherwise specified, the reagents, methods, instruments and equipment used in this invention are conventional reagents, methods, instruments and equipment in the art.

[0028] A method for preparing a CuO / TiO2 photothermal catalyst is disclosed, which employs an impregnation-calcination method. The preparation process involves uniformly mixing a soluble copper salt precursor solution with a titanium dioxide support, followed by ultrasonication, settling, drying, and calcination to obtain the CuO / TiO2 catalyst.

[0029] In some specific embodiments, the soluble copper salt in the soluble copper salt precursor solution is one or more of copper nitrate, copper acetate, or copper chloride, preferably copper nitrate; its concentration is 0.01~0.5 mol / L, preferably 0.026~0.39 mol / L; The titanium dioxide support is anatase, rutile, or a mixture of both.

[0030] In some specific embodiments, the mixed crystal form of anatase and rutile is nanoscale titanium dioxide, and the mass ratio of the two is 3 to 5:1, preferably 4:1. When the mass ratio is 4:1, the titanium dioxide carrier is usually referred to as type P25.

[0031] In some specific embodiments, the CuO loading in the CuO / TiO2 catalyst is 1wt% to 15wt%, preferably 5wt% to 15wt%.

[0032] In some specific embodiments, the ultrasound duration is 0.5 to 3 hours; The drying temperature is 100~140℃, and the time is 6~48h; The calcination atmosphere is air or an oxygen-containing atmosphere, the calcination temperature is 300~500℃, preferably 350~450℃, and the heating rate is 0.5~5℃ / min, preferably 0.5~2℃ / min.

[0033] A CuO / TiO2 photothermal catalyst, which is prepared by the method described above.

[0034] The third technical solution of the present invention is to provide an application of a CuO / TiO2 photothermal catalyst, wherein the CuO / TiO2 photothermal catalyst is used for the photothermal catalytic degradation of plastics to obtain liquid fuel; The liquid fuel is aviation fuel fraction C8-C. 16 Or diesel fraction C 10 -C 23 One or more of them.

[0035] In some specific embodiments, the plastic includes one or more of LDPE, HDPE, PP, PS, PET, and PLA.

[0036] A method for photothermal catalytic degradation of plastics includes the following steps: S1. Mix the plastic with the CuO / TiO2 photothermal catalyst as described in claim 5 and place it in a reactor; S2. Photothermal catalytic reaction is carried out under light and heating conditions; S3. Collect the reactants to obtain liquid fuel oil; The liquid fuel is aviation fuel fraction C8-C. 16 Or diesel fraction C 10 -C 23 One or more of them.

[0037] In some specific embodiments, in step S1, the mass ratio of the plastic to the CuO / TiO2 photothermal catalyst is 1~5:1, preferably 1.5~2.5:1; In step S2, the illumination is provided by simulating a solar light source, and the heating temperature is 200~350℃, preferably 240~320℃. In step S2, the photothermal catalytic reaction is carried out in an inert atmosphere or vacuum environment for a reaction time of 2 to 20 hours, preferably 4 to 12 hours.

[0038] In some specific embodiments, the simulated solar light source is provided by a xenon lamp with a power of 200~1000W, and is focused by a Fresnel lens to enhance the photothermal effect.

[0039] In some specific embodiments, in step S3, the liquid fuel is preferably an aviation fuel fraction C8-C. 16 .

[0040] In some specific embodiments, in step S3, the aviation fuel fraction C8-C 16 The selectivity is 50%~90%, and the diesel fraction C 10 -C 23 The selectivity is 65%~85%.

[0041] In some specific embodiments, in step S2, the photothermal catalytic reaction is a photothermal synergistic catalytic process, that is, the reaction temperature is mainly provided by the thermal energy converted from light energy, and the light simultaneously excites and generates photogenerated carriers to participate in the reaction. This process is significantly different from single thermal catalysis or photocatalysis.

[0042] Each of the above embodiments can be implemented individually or in any combination of two or more.

[0043] The following description uses specific examples to illustrate the point.

[0044] Example 1 A method for preparing CuO / TiO2 photothermal catalyst 1, using an impregnation-calcination method, the preparation process is as follows: (1) Preparation of precursor solution Weigh 18.9 mg of copper nitrate trihydrate solid and place it in a 50 mL polytetrafluoroethylene beaker. Add 3 mL of deionized water. Place the beaker in an ultrasonic cleaner and sonicate for 20 min until the solution turns clear blue and the solid is completely dissolved, thus obtaining the copper nitrate precursor solution.

[0045] (2) Impregnation and dispersion Add 500 mg of TiO2 (P25) powder to the copper nitrate precursor solution obtained in step (1) to obtain a mixed system. Continue to sonicate the mixed system for 1 h to ensure that the carrier is uniformly dispersed in the solution and forms a stable suspension.

[0046] (3) Static aging The suspension obtained in step (2) was left to stand at room temperature for 12 h to complete the aging process, which promoted the adsorption of the precursor on the surface of the carrier, and the mixture after standing and aging was obtained.

[0047] (4) Drying The mixture obtained in step (3) after static aging was transferred to a clean corundum crucible and dried in a constant temperature drying oven at 120°C for 2 hours until completely dried.

[0048] (5) Calcination activation The dried solid sample obtained in step (4) was placed in a muffle furnace and calcined in air. The calcination program was set as follows: the temperature was increased from room temperature to 400℃ at a heating rate of 1℃ / min, and held at 400℃ for 4 h. After the program was completed, the sample was allowed to cool naturally to room temperature in the muffle furnace to obtain CuO / TiO2 photothermal catalyst 1 powder, wherein the CuO loading was 1wt%.

[0049] Example 2 Compared with Example 1, except that the amount of copper nitrate trihydrate solid weighed is 94.5 mg and the loading of CuO in CuO / TiO2 photothermal catalyst 1 is 5 wt%, everything else is the same.

[0050] Example 3 Compared with Example 1, except that the amount of copper nitrate trihydrate solid weighed is 189.0 mg and the loading of CuO in CuO / TiO2 photothermal catalyst 1 is 10 wt%, everything else is the same.

[0051] Example 4 Compared with Example 1, except that the amount of copper nitrate trihydrate solid weighed is 283.5 mg and the loading of CuO in CuO / TiO2 photothermal catalyst 1 is 15 wt%, everything else is the same.

[0052] Comparative Example 1 Compared with Example 1, except that the amount of copper nitrate trihydrate solid weighed is 9.4 mg and the loading of CuO in CuO / TiO2 photothermal catalyst 1 is 0.5 wt%, everything else is the same.

[0053] Comparative Example 2 Compared with Example 1, the only difference is that a physical mixing method is used instead of the impregnation-calcination method. 55.6 mg of CuO powder and 500 mg of P25 type TiO2 powder were weighed and ground and mixed thoroughly in a mortar for 30 minutes to obtain a physically mixed catalyst (the mass fraction of CuO was 10%).

[0054] Performance testing: I. Different CuO loading Examples 1-4 show CuO / TiO2 photothermal catalysts 1 with different CuO loadings (0.5 wt%, 1 wt%, 5 wt%, 10 wt%, and 15 wt%). The CuO / TiO2 photothermal catalyst 1 with a CuO loading of 0.5 wt% is white, the CuO / TiO2 photothermal catalyst 1 with a CuO loading of 1 wt% is light green, and the sample with a CuO loading of 5.0 wt% is light gray. As the loading increases to 10.0 wt% and 15.0 wt%, the color of the CuO / TiO2 photothermal catalyst 1 gradually deepens from light gray to dark gray.

[0055] TEM image of CuO / TiO2 photothermal catalyst 1 prepared in Example 3 with a CuO loading of 10 wt% is shown below. Figure 1 As shown, high-density CuO nanoclusters (marked by red circles in the figure) are distributed on the surface of the TiO2 support in an approximately spherical shape.

[0056] The XRD patterns of CuO / TiO2 photothermal catalysts 1 with different CuO loadings are shown below. Figure 2 As shown, CuO / TiO2 photothermal catalysts 1 with CuO active component 12 loadings of 10 wt% and 15 wt% exhibit obvious CuO characteristic diffraction peaks at 2θ = 35.5° and 38.8°, proving that copper in the high-loading samples mainly exists in the CuO crystalline phase. However, for CuO / TiO2 photothermal catalysts with CuO loadings of 0.5 wt%, 1 wt%, and 5 wt%, only TiO2 diffraction peaks were observed in the XRD patterns due to the lower copper loadings. Furthermore, the position and intensity of the strong diffraction peaks of the TiO2 support 11 in CuO / TiO2 photothermal catalysts 1 did not change significantly with different loadings.

[0057] For CuO / TiO2 photothermal catalyst 1 with different CuO loadings (0.5wt%, 1wt%, 5wt%, 10wt%, 15wt%) in Examples 1-4, as shown in... Figure 3 The photothermal catalytic reaction apparatus shown was used to conduct a polyethylene plastic degradation experiment. The specific steps are as follows: 20 mg of plastic 2 (LDPE) and 10 mg of CuO / TiO2 photothermal catalyst were weighed and placed in a mortar, ground and mixed evenly, and then placed on the quartz support platform 37 inside the photochemical quartz reactor 31. The inside of the photochemical quartz reactor 31 was evacuated to a vacuum state using a vacuum pump. The photochemical quartz reactor 31 was placed on a heat-insulating plate, and a 500W xenon lamp 36 was used as a simulated sunlight source. A 10 cm diameter Fresnel lens 35 was used to focus parallel light so that the light spot exactly covered the reactant area at the bottom of the photochemical quartz reactor 31. The temperature at the center of the light spot was measured to be 280℃ (±15℃) by thermocouple 3. The reaction was carried out under these conditions for 6 h. After the reaction, the collected liquid product was analyzed using gas chromatography-mass spectrometry (GC-MS) instrument 4. The product was analyzed using C8-C... 16 and C 10 -C 23 The relative peak area percentage of hydrocarbons was used as a semi-quantitative evaluation index for the selectivity of aviation fuel and diesel fractions.

[0058] Qualitative and semi-quantitative analysis of the liquid products was performed using GC-MS instrument 4, with the following specific test conditions: Instrument model: GC-MS (Shimadzu QP2020); Column: SH-5MS, 30 m × 0.25 mm × 0.25 μm; Carrier gas: Helium (He); Carrier gas flow rate: 1.0 mL / min (constant flow rate); Inlet temperature: 280℃; Column oven program: Initial temperature 40℃, hold for 5 min; increase temperature to 280℃ at a rate of 10℃ / min, hold for 20 min; Mass spectrometer detector temperature: 280℃; Ionization method: Electron bombardment ionization (EI), electron energy 70 eV; Quality scanning range: 35~500 m / z.

[0059] The pretreatment method for the liquid product is as follows: after the reaction is completed, the reaction solid residue is extracted with n-hexane, and the clear test solution is obtained after centrifugation and filtration.

[0060] The qualitative and quantitative analysis process is as follows: Qualitative identification is performed by comparing the matching degree (similarity index SI > 90%) and retention time of unknown components with the NIST standard mass spectrometry library. Semi-quantitative analysis is then conducted using the relative peak area of ​​each identified component in the total ion chromatogram as an evaluation index of its relative content, thereby assessing the compositional distribution of the liquid product under different conditions.

[0061] Table 1 shows the degradation liquid products of plastic 2 by CuO / TiO2 photothermal catalyst 1 with different CuO loadings (0.5wt%, 1wt%, 5wt%, 10wt%, 15wt%).

[0062] Table 1 shows the liquid products of plastic degradation by CuO / TiO2 photothermal catalysts with different CuO loadings. The results are shown in Table 1. Under the same reaction conditions, the performance of CuO / TiO2 photothermal catalyst 1 showed a trend of first increasing and then decreasing with the change of CuO loading. When the CuO loading was 10 wt%, CuO / TiO2 photothermal catalyst 1 showed a better performance for aviation fuel components C8-C. 16 The selectivity was highest, reaching 86.06%. When the CuO loading was only 0.5 wt%, the CuO nanocluster density on the TiO2 surface was severely insufficient. Its aviation fuel C8-C... 16 The selectivity decreased to 42.03%. During photothermal catalysis, there were insufficient active sites to adsorb LDPE long chains and capture hydrogen atoms from the polymer chains. Due to the inability to provide a sufficient density of catalytic centers to promote the breaking of C-C and CH bonds and lock the carbon number distribution, the carbon number distribution of the product became broad again, and the selectivity decreased significantly.

[0063] Simultaneously, for wide-range liquid fuel C 10 -C 23 It also exhibits optimal enrichment ability, with the carbon atom number distribution of the product as follows: Figure 4 As shown in the figure, this indicates the existence of an optimal loading level, at which the density and dispersion of active sites in CuO / TiO2 photothermal catalyst 1 reach the best balance, thereby achieving the highest photothermal catalytic activity and product selectivity. Too low a CuO loading level results in insufficient active sites; too high a CuO loading level may lead to agglomeration of active components, which in turn reduces the effective active area and catalytic efficiency.

[0064] II. Different reaction temperatures The CuO / TiO2 photothermal catalyst 1 with a CuO loading of 10 wt% as described in Example 3 was used in... Figure 3 The photothermal catalytic reaction apparatus shown was used to conduct a polyethylene plastic degradation experiment. The specific steps are as follows: 20 mg of plastic 2 (LDPE) and 10 mg of CuO / TiO2 photothermal catalyst were weighed and placed in a mortar, ground and mixed evenly, and then placed on the quartz support platform 37 inside the photochemical quartz reactor 31. The inside of the photochemical quartz reactor 31 was evacuated to a vacuum state using a vacuum pump. The photochemical quartz reactor 31 was placed on a heat-insulating plate, and a 500W xenon lamp 36 was used as a simulated sunlight source. A 10 cm diameter Fresnel lens 35 was used to focus parallel light so that the light spot exactly covered the reactant area at the bottom of the photochemical quartz reactor 31. The light intensity was controlled by adjusting the current of the xenon lamp 36, and the center temperature of the light spot was controlled at 200, 240, 280, and 320℃ (±15℃) as measured by thermocouple 3. The photoreaction was carried out under these conditions for 6 h. After the reaction, the collected liquid product was analyzed using a GC-MS instrument 4. The product was analyzed using C8-C... 16 and C 10 -C 23 The relative peak area percentage of hydrocarbons was used as a semi-quantitative evaluation index for the selectivity of aviation fuel and diesel fractions.

[0065] Table 2 shows the degradation liquid products of plastic 2 by CuO / TiO2 photothermal catalyst 1 at different temperatures.

[0066] Table 2 shows the liquid products of plastic degradation by CuO / TiO2 photothermal catalyst at different temperatures. The results are shown in Table 2. Under the conditions of CuO / TiO2 photothermal catalyst 1 and fixed reaction time, the product selectivity is significantly temperature-dependent. When the reaction temperature is 280℃, the target aviation fuel component (C8-C) in the liquid product... 16 The relative content of ) reached its highest level (86.06%), and the carbon number distribution of the product was as follows. Figure 5 As shown in the figure. This indicates that this temperature is the optimal balance point for selective carbon chain breakage and recombination in this system. At excessively low temperatures, polymer pyrolysis is insufficient, and long-chain molecules are difficult to break effectively, leading to the loss of light fractions (C8-C4). 16 The selectivity is low; if the temperature is too high, it may cause excessive cracking or secondary reactions, leading to the further decomposition of some target components into smaller molecules, thus reducing their selectivity. Therefore, 280℃ is currently the optimal temperature, and maintaining the reaction temperature within a suitable range is crucial for achieving highly selective conversion of polyethylene into high-value aviation fuel components.

[0067] III. Different reaction times The CuO / TiO2 photothermal catalyst 1 with a CuO loading of 10 wt% as described in Example 3 was used in... Figure 3 The photothermal catalytic reaction apparatus shown was used to conduct a polyethylene plastic degradation experiment. The specific steps are as follows: 20 mg of plastic 2 (LDPE) and 10 mg of CuO / TiO2 photothermal catalyst were weighed and placed in a mortar, ground and mixed evenly, and then placed on the quartz support platform 37 inside the photochemical quartz reactor 31. The inside of the photochemical quartz reactor 31 was evacuated to a vacuum state using a vacuum pump. The photochemical quartz reactor 31 was placed on a heat-insulating plate, and a 500W xenon lamp 36 was used as a simulated sunlight source. A 10 cm diameter Fresnel lens 35 was used to focus parallel light so that the light spot exactly covered the reactant area at the bottom of the photochemical quartz reactor 31. The temperature at the center of the light spot was measured to be 280℃ (±15℃) by thermocouple 3. The photoreaction was carried out under these conditions for 2, 4, 6, 8, 10, and 12 h. After the reaction, the collected liquid products were analyzed using GC-MS instrument 4. The reaction was carried out using C8-C... 16 and C 10 -C 23 The relative peak area percentage of hydrocarbons was used as a semi-quantitative evaluation index for the selectivity of aviation fuel and diesel fractions.

[0068] Table 3 shows the liquid products of plastic 2 degradation by CuO / TiO2 photothermal catalyst 1 at different reaction times.

[0069] Table 3 shows the liquid products of plastic degradation by the CuO / TiO2 photothermal catalyst at different reaction times. Table 3 shows that, under optimal CuO loading and reaction temperature, reaction time has a crucial impact on product distribution. When the reaction time is 6 h, the target fraction of aviation fuel (C8-C9)... 16 The selectivity of the product reached its peak (86.06%), and the carbon number distribution of the product was as follows: Figure 6 As shown. When the reaction time is too short, polyethylene fails to fully pyrolyze and recombine, resulting in a higher proportion of intermediate products and long-chain components, C8-C. 16 The selectivity is low. While prolonged reaction times may lead to more complete conversion, excessive reaction can cause secondary cracking, excessive dehydrogenation, or condensation and coking of some of the already formed ideal intermediates, resulting in C8-C... 16 Selectivity decreases. Therefore, a reaction time of 6 hours is currently the optimal reaction time, and maintaining the reaction time within a suitable range is key to achieving highly selective preparation of aviation fuel components.

[0070] IV. Different Catalysts The CuO / TiO2 photothermal catalyst 1 with a CuO loading of 10 wt% from Example 3, pure TiO2 catalyst 1, and the CuO / TiO2 photothermal catalyst from Comparative Example 2 were used in the following conditions: Figure 3The photothermal catalytic reaction apparatus shown was used to conduct a polyethylene plastic degradation experiment, with a control group operating without a catalyst. The specific steps are as follows: 20 mg of plastic 2 (LDPE) and 10 mg of catalyst (CuO / TiO2 photothermal catalyst from Example 1 and Comparative Example 2, and pure TiO2 catalyst, respectively) were weighed and placed in a mortar, ground and mixed evenly, and then placed on the quartz support platform 37 inside the photochemical quartz reactor 31. The interior of the photochemical quartz reactor 31 was evacuated to a vacuum state using a vacuum pump. The photochemical quartz reactor 31 was placed on a heat-insulating plate, and a 500W xenon lamp 36 was used as a simulated sunlight source. A 10 cm diameter Fresnel lens 35 was used to focus parallel light so that the light spot exactly covered the reactant area at the bottom of the photochemical quartz reactor 31. The temperature at the center of the light spot was measured to be 280℃ (±15℃) by thermocouple 3. The reaction was carried out under these conditions for 6 hours. After the reaction, the collected liquid product was analyzed using a GC-MS instrument 4. The product was analyzed using C8-C... 16 and C 10 -C 23 The relative peak area percentage of hydrocarbons was used as a semi-quantitative evaluation index for the selectivity of aviation fuel and diesel fractions.

[0071] Meanwhile, the step without a catalyst is as follows: 20 mg of plastic 2 (LDPE) was weighed and placed in a mortar, ground and mixed evenly, and then placed on the quartz platform 37 inside the photochemical quartz reactor 31. The inside of the photochemical quartz reactor 31 was evacuated to a vacuum state using a vacuum pump. The photochemical quartz reactor 31 was placed on a heat-insulating plate, and a 500W xenon lamp 36 was used as a simulated sunlight source. A 10 cm diameter Fresnel lens 35 was used to focus parallel light so that the light spot exactly covered the reactant area at the bottom of the photochemical quartz reactor 31. The temperature at the center of the light spot was measured to be 280℃ (±15℃) by thermocouple 3. The reaction was carried out under these conditions for 6 hours. After the reaction, the collected liquid product was analyzed using a GC-MS instrument 4. The product was analyzed using C8-C... 16 and C 10 -C 23 The relative peak area percentage of hydrocarbons was used as a semi-quantitative evaluation index for the selectivity of aviation fuel and diesel fractions.

[0072] Table 4 shows the liquid products of plastic 2 degradation under different catalysts.

[0073] Table 4 shows the liquid products of plastic degradation under different catalysts. The results are shown in Table 4. Without using any catalyst, simply placing LDPE in a photopolymer reactor and irradiating it at 280°C for 6 hours resulted in a liquid product containing aviation fuel in the C8-C9 range.16 The peak area of ​​hydrocarbons accounted for only 9.56%, while that of diesel (C) 10 -C 23 The proportion of hydrocarbons was only 11.68%. Furthermore, data shows that a CuO / TiO2 photothermal catalyst with a CuO loading of 10 wt% is effective against C8-C9 aviation fuel. 16 The selectivity of the catalyst (86.06%) was more than twice that of the pure TiO2 catalyst (41.26%); for diesel (C 10 -C 23 The selectivity of the copper oxide catalyst (84.52%) was also significantly higher than that of the pure TiO2 catalyst (56.36%). This demonstrates that loading copper oxide can significantly improve the performance of the catalyst, thereby greatly enhancing the selectivity for the target liquid fuel.

[0074] Using a simple physical mixing method, its aviation fuel C8-C 16 The selectivity was only 42.71%, diesel C 10 -C 23 The selectivity was only 53.16%. There was only weak van der Waals contact between CuO and TiO2, making it impossible to form a tight interfacial structure. However, the embodiment of this invention uses an impregnation-calcination method, which allows photogenerated electrons under light excitation to smoothly transfer directionally from the conduction band of TiO2 to the CuO clusters, driving subsequent charge transfer. The physical mixing method lacks this crucial interfacial synergistic effect, resulting in an inability to accurately guide the isomerization and recombination pathways of intermediate products, thus failing to suppress excessive carbon chain fragmentation and significantly reducing the selectivity of the target high-value fraction.

[0075] The above results indicate that while the photothermal effect alone can provide the energy required for the reaction, its activation and cleavage processes of LDPE molecular chains are random and non-directional. The reaction mainly relies on the direct breaking of C-C bonds by photon energy and the thermal energy generated by photothermal conversion to promote molecular motion. However, the lack of specific active sites provided by a catalyst makes it difficult for the free radical fragments generated by bond breaking to undergo effective shape-selective recombination and secondary reactions such as aromatization and isomerization. This results in extremely dispersed product distribution, generating a large amount of hydrocarbon mixtures with a wide range of carbon numbers and complex structures, thus exhibiting extremely low selectivity for high-value aviation fuel and diesel middle fractions.

[0076] V. Different light and heat conditions To avoid the influence of light, 20 mg of CuO / TiO2 photothermal catalyst 1 with a CuO loading of 10.0% was uniformly mixed with 40 mg of LDPE and placed in a quartz reaction tube for pure thermal catalysis experiments in a fixed-bed reactor. The reaction zone temperature was controlled at approximately 300℃, 330℃, and 360℃ using an external heating furnace, with each reaction lasting 6 h. After the reaction, the liquid products were analyzed by GC-MS.

[0077] Table 5 shows the liquid products of plastic degradation by CuO / TiO2 photothermal catalyst at different temperatures under pure heat conditions.

[0078] Table 5 shows the liquid products of plastic degradation by the CuO / TiO2 photothermal catalyst at different temperatures under pure heat conditions. The results are shown in Table 5. Under pure thermocatalytic conditions with no light and relying solely on external heating, even using the same CuO / TiO2 photothermal catalyst 1 with a CuO loading of 10.0% and reacting at higher temperatures (300-360℃) for 6 h, its catalytic conversion effect on LDPE remained limited. As the temperature increased from 300℃ to 360℃, the catalytic conversion effect on aviation fuel (C8-C90) decreased. 16 The selectivity of hydrocarbons increased only slowly from 22.71% to 37.82%, while the selectivity of diesel (C) range... 10 -C 23 The selectivity for hydrocarbons increased from 31.62% to 41.25%. Even at a purely thermal catalytic temperature of 360°C, its selectivity for C8-C hydrocarbons remained high. 16 The selectivity (37.82%) is still far lower than that of photothermal catalysis at 280℃ (86.06%). This control experiment clearly demonstrates that illumination is a key factor in activating the high performance of the CuO / TiO2 photothermal catalyst described in this invention. Under conditions lacking illumination, even with increased reaction temperature, the CuO / TiO2 photothermal catalyst system cannot achieve efficient and targeted conversion of LDPE into hydrocarbons in the aviation fuel and diesel range. Illumination not only provides some energy, but more importantly, it generates electron-hole pairs through photoexcitation of the TiO2 support, producing a synergistic effect with surface CuO species, significantly reducing the energy barriers for CC and CH bond activation, thereby achieving high-selectivity and high-value conversion of waste plastics under relatively mild conditions. Therefore, illumination is an essential element for achieving the excellent technical effects of this invention.

[0079] VI. Stability and Recyclability Testing To verify the stability and recyclability of the CuO / TiO2 photothermal catalyst 1 described in this invention, a catalyst recycling experiment was conducted. The solid residue after the degradation reaction of polyethylene plastic (containing unreacted LDPE, waxy products, and catalyst) was dissolved in a hot 1,2,4-trichlorobenzene solution, and the resulting catalyst precipitate was obtained by centrifugation. This precipitate was then washed sequentially with 1,2,4-trichlorobenzene, dichloromethane, and ethanol to thoroughly remove any attached organic matter, and finally dried at 100°C, thus completing the catalyst recovery.

[0080] Under the same optimal reaction conditions (20 mg of plastic 2 and 10 mg of CuO / TiO2 photothermal catalyst, reaction temperature 280℃, vacuum environment, and 6 h of illumination), LDPE was subjected to eight consecutive degradation experiments using the same batch of CuO / TiO2 photothermal catalyst 1 with a CuO loading of 10.0%. The results showed that, compared with fresh CuO / TiO2 photothermal catalyst, the recycled CuO / TiO2 photothermal catalyst maintained stable performance, and the C8-C content in the liquid product remained relatively stable. 16 The relative peak area percentage of aviation fuel components remained between 83.21% and 86.06% (e.g., Figure 7 (As shown in the figure). This result confirms that the CuO / TiO2 photothermal catalyst of the present invention has good reusability and cycling stability.

[0081] Although the present invention has been described in detail above with general descriptions, specific embodiments, and experiments, modifications or improvements can be made to it, which will be obvious to those skilled in the art. Therefore, all such modifications or improvements made without departing from the spirit of the present invention fall within the scope of protection claimed by the present invention.

Claims

1. A method for preparing a CuO / TiO2 photothermal catalyst, characterized in that, The CuO / TiO2 catalyst was prepared by impregnation-calcination method. The preparation process is as follows: a soluble copper salt precursor solution is uniformly mixed with a titanium dioxide support, followed by ultrasonication, standing, drying, and calcination to obtain the CuO / TiO2 catalyst.

2. The method for preparing a CuO / TiO2 photothermal catalyst according to claim 1, characterized in that, The soluble copper salt in the soluble copper salt precursor solution is one or more of copper nitrate, copper acetate, or copper chloride, and its concentration is 0.01~0.5 mol / L; The titanium dioxide support is anatase, rutile, or a mixture of both.

3. The method for preparing a CuO / TiO2 photothermal catalyst according to claim 1, characterized in that, The CuO loading in the CuO / TiO2 catalyst is 1wt%~15wt%.

4. The method for preparing a CuO / TiO2 photothermal catalyst according to claim 1, characterized in that, The drying temperature is 100~140℃; The calcination atmosphere is air or an oxygen-containing atmosphere, the calcination temperature is 300~500℃, and the heating rate is 0.5~5℃ / min.

5. A CuO / TiO2 photothermal catalyst, which is prepared by any one of the preparation methods described in claims 1 to 4.

6. The application of the CuO / TiO2 photothermal catalyst as described in claim 5, characterized in that, The CuO / TiO2 photothermal catalyst is used for the photothermal catalytic degradation of plastics to obtain liquid fuel. The liquid fuel C8-C 16 Aviation fuel fraction or diesel fraction C 10 -C 23 One or more of them.

7. The application of the CuO / TiO2 photothermal catalyst according to claim 6, characterized in that, The plastic includes one or more of low-density polyethylene, high-density polyethylene, polypropylene, polystyrene, polyethylene terephthalate, and polylactic acid.

8. A method for photothermal catalytic degradation of plastics, characterized in that, Includes the following steps: S1. Mix the plastic with the CuO / TiO2 photothermal catalyst as described in claim 5 and place it in a reactor; S2. Photothermal catalytic reaction is carried out under light and heating conditions; S3. Collect the reactants to obtain liquid fuel oil; The liquid fuel is aviation fuel fraction C8-C. 16 Or diesel fraction C 10 -C 23 One or more of them.

9. The method for photothermal catalytic degradation of plastics according to claim 8, characterized in that, In step S1, the mass ratio of the plastic to the CuO / TiO2 photothermal catalyst is 1~5:1; In step S2, the illumination is provided by simulating a solar light source, and the heating temperature is 200~350℃; In step S2, the photothermal catalytic reaction is carried out in an inert atmosphere or vacuum environment.

10. The method for photothermal catalytic degradation of plastics according to claim 8, characterized in that, In step S3, the aviation fuel fraction C8-C 16 The selectivity is 50%~90%, and the diesel fraction C 10 -C 23 The selectivity is 65%~85%.

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