Method for recycling polyester plastics into intercalated layered high-entropy hydrotalcite for efficient photocatalytic reduction of CO2

Abstract

The application discloses a method for converting polyester plastic into intercalated layered high-entropy hydrotalcite for efficient photocatalytic CO2 reduction, and belongs to the field of chemical recycling, upgrading and conversion of fine chemical products. The method for preparing high-entropy hydrotalcite from polyester plastic comprises the following steps: putting polyester plastic into alkali liquor, reacting to obtain solution A; mixing the solution A with high-entropy metal salt, and reacting, and the obtained solid is the high-entropy hydrotalcite. The high-entropy LDHs is used for photocatalytic CO2 reduction, and the interlayer spacing is expanded due to the interlayer anions of the high-entropy LDHs, so that CO2 can be effectively adsorbed and the mass transfer performance can be accelerated; meanwhile, the high-entropy effect caused by the multi-metals in the LDHs effectively promotes the transmission of electron holes, promotes the conversion efficiency of photocatalytic CO2 into CH4 and CO, and has obvious performance advantages.

Description

Technical Field

[0001] This invention relates to the field of plastic chemical recycling and upgrading to fine chemical products, and in particular to a method for recycling polyester plastics into intercalated layered high-entropy hydrotalcite for efficient photocatalytic CO2 reduction. Background Technology

[0002] Plastics are a widely used material in packaging, construction, automobiles, electronics, and other fields. Traditional plastic disposal methods, including landfill and incineration, are detrimental to environmental protection. While traditional physical recycling methods have some application potential, they are limited by economic efficiency and the degradation of the properties of recycled plastics. In contrast, the effective utilization of waste plastic resources through chemical recycling technologies has attracted much attention. Chemical recycling of plastics refers to the process of obtaining monomers or converting them into high-value-added chemicals or fine chemical materials through chemical methods such as hydrolysis and transesterification.

[0003] Compared to traditional physical recycling and incineration / landfill methods, chemical recycling can achieve efficient conversion and resource utilization of waste plastics, reducing negative environmental impacts. Among various plastics, polyester plastics such as polyethylene terephthalate (PET), polylactic acid (PLA), and polybutylene terephthalate (PBT) are widely used. Their polymer backbones have easily broken ester bonds, making them a common target for chemical recycling compared to other plastics. Currently, methods such as alcoholysis and acid-base hydrolysis are being extensively researched and developed. For example, PLA can be hydrolyzed into lactic acid under high temperature and pressure, and PET can be hydrolyzed by alkali (NaOH or KOH) into disodium / potassium terephthalate and ethylene glycol. However, these methods all suffer from difficulties in separating the products in solution. More importantly, the reaction process requires a large amount of alkali and generates a large amount of inorganic wastewater. Considering both economic cost and pollution friendliness, these methods limit their commercial application. Therefore, developing new waste plastic recycling methods is essential.

[0004] Layered bimetallic hydroxides (LDHs), also known as hydrotalcites, are formed by the electrostatic interaction between a positively charged cation layer and interlayer anions, and their general formula is [M]. 1-x 2+ M x 3+ (OH)2] x+ (A x / n n- )·mH2O, where M 2+ (e.g. Mg) 2+ Ca 2+ Mn 2+ Fe 2+ Co 2+ Ni 2+ Cu 2+ Zn 2+(etc.) and M 3+ (Fe 3+ Al 3+ Ce 3+ (etc.) are divalent and trivalent metal cations, respectively, A n- These are interlayer anions, including inorganic anions (Cl...). - NO3 - CO3 2- Layered double hydroxides (LDHs) contain organic anions such as amino acids, heteropoly acids, and lactate (LA). Due to the tunable nature of their interlayer ions and the exchangeability of interlayer anions, LDHs have a wide range of applications, including adsorption, separation, catalysis, energy storage, and biomedicine. Because of the exchangeability of anions in the LDH interlayers, many organic acid ions can intercalate into the LDH layers, thereby modulating their physicochemical properties and expanding their application range. For example, intercalated LDHs can act as adsorbents to enhance the capture capacity of organic pollutants or heavy metals in wastewater; as photocatalysts, intercalated LDHs enhance electron-hole separation through the interaction between anions and interlayer metals, thus improving photocatalytic efficiency; and as drug carriers, intercalated LDHs can regulate the release rate of drug molecules through the regulation of interlayer anions, achieving sustained drug release. Currently, LDHs can usually be synthesized by hydrothermal method, anion exchange method, and coprecipitation method. However, the above methods are mainly for inorganic anions. In contrast, organic anions have long molecular chains and are relatively expensive, which limits their practical application in terms of both process and cost. There is an urgent need to design new methods for synthesizing organic anions.

[0005] Furthermore, currently synthesized LDHs are mainly bimetallic or trimetallic LDHs; in contrast, research reports on multimetallic or even high-entropy LDHs are still relatively rare. In recent years, high-entropy materials have demonstrated significant superior performance in numerous fields due to their unique cocktail effect. Therefore, designing and synthesizing novel high-entropy intercalated LDHs is expected to promote further research on high-entropy layered double hydroxides (LDHs) and expand their application prospects. Summary of the Invention

[0006] The purpose of this invention is to provide a method for recycling polyester plastics into intercalated layered high-entropy hydrotalcite (LDHs) for efficient photocatalytic CO2 reduction. This invention utilizes high-entropy LDHs for photocatalytic CO2 reduction. The interlayer anions in high-entropy LDHs expand the interlayer spacing, effectively adsorbing CO2 and accelerating mass transfer. Simultaneously, the high-entropy effect caused by the polymetallic composition of LDHs effectively promotes electron-hole transfer, enhancing the photocatalytic conversion efficiency of CO2 to CH4 and CO, resulting in significant performance advantages. Compared to traditional plastic recycling methods, this process achieves efficient utilization of plastic waste and waste alkali, thus offering advantages in both economic benefits and environmental friendliness.

[0007] To achieve the above objectives, the present invention provides the following technical solution:

[0008] One of the technical solutions of this invention is to provide a method for preparing high-entropy hydrotalcite using polyester plastics, comprising the following steps:

[0009] (1) The polyester plastic is placed in an alkaline solution and reacted to obtain solution A;

[0010] (2) Mix the solution A with the high-entropy metal salt and react to obtain the high-entropy hydrotalcite.

[0011] Preferably, the ratio of the polyester plastic to the high-entropy metal salt is 16-48g:0.3-0.4mol.

[0012] Preferably, in step (1): the amount of polyester plastic added is 20-60 g / L. -1 .

[0013] Preferably, in step (1), the alkaline solution is a NaOH solution.

[0014] More preferably, the concentration of the NaOH solution is 1M.

[0015] Preferably, in step (1), the reaction temperature is 120°C and the time is 6 hours.

[0016] Polyester plastics are 100% hydrolyzed after reacting for 6 hours under the conditions specified in this invention.

[0017] Preferably, in step (2): the high-entropy metal salt contains five or more metal salts; the metal salts include divalent metal salts and trivalent metal salts; the total concentration of the divalent metal salts is 0.2-0.3M, and the total concentration of the trivalent metal salts is 0.1M.

[0018] More preferably, the divalent metal salt includes one or more of magnesium salts, calcium salts, iron salts, cobalt salts, copper salts, nickel salts, and zinc salts; the trivalent metal salt includes one or more of aluminum salts, iron salts, and cerium salts.

[0019] Preferably, in step (2): the reaction temperature is 25-75℃ and the time is 12h.

[0020] The second technical solution of the present invention provides a high-entropy hydrotalcite obtained according to the above preparation method.

[0021] The third technical solution of the present invention provides an application of the above-mentioned high-entropy hydrotalcite in the field of photocatalytic CO2 reduction.

[0022] The beneficial technical effects of the present invention are as follows:

[0023] This invention proposes a method for synthesizing high-entropy intercalated LDHs using the chemical recycling of polyester plastic waste. The method utilizes terephthalate (TPA) and lactate (LA) ions generated after the hydrolysis of polyester plastics such as PET, PBT, and PLA as anion sources for LDH synthesis, resulting in the synthesis of multi-metallic high-entropy LDHs. This method efficiently utilizes the organic acid ions from the decomposition products of alkaline hydrolysis of waste polyester plastics, and also utilizes the waste alkali from the alkaline hydrolysis process to synthesize high-specific-surface-area, defect-rich organic acid-intercalated high-entropy LDHs. Compared to traditional methods for synthesizing intercalated LDHs that require high-cost organic acids, this method, by recycling plastic monomers as raw materials, has the advantage of high economic efficiency. Simultaneously, this method provides a new pathway for the efficient resource utilization of polyester plastic waste; compared to traditional plastic recycling methods, the entire process achieves efficient utilization of plastic waste and waste alkali, thus offering greater advantages in terms of economic benefits and environmental friendliness.

[0024] This invention utilizes alkaline hydrolysis to treat waste polyester plastics while effectively using the hydrolysis products and residual alkali to synthesize economically viable high-entropy organic acid-intercalated LDHs. Furthermore, other organic molecules, such as ethylene glycol, produced during polyester plastic hydrolysis can act as surfactants, controlling the morphology of LDHs and thus modulating their physicochemical properties. This includes altering the shape and size of LDH particles and influencing their surface charge distribution. It can be used for the photocatalytic conversion of CO2 into high-value-added solar fuels and is expected to have broad application value in other fields. The waste alkali from the alkaline hydrolysis process can neutralize acidic substances and maintain the stability of the LDH layered structure during subsequent synthesis.

[0025] This invention utilizes high-entropy LDHs for photocatalytic CO2 reduction. Due to the interlayer anions in high-entropy LDHs, the interlayer spacing is expanded, which can effectively adsorb CO2 and accelerate mass transfer. At the same time, the high-entropy effect caused by the polymetals in LDHs effectively promotes the transfer of electrons and holes, thereby improving the conversion efficiency of photocatalytic CO2 to CH4 and CO, showing significant performance advantages. Attached Figure Description

[0026] Figure 1 The image shows the X-ray diffraction spectrum of the product from Example 1.

[0027] Figure 2 This is a scanning electron microscope image of the product from Example 1.

[0028] Figure 3 The image shows the X-ray diffraction spectrum of the product from Example 2.

[0029] Figure 4 The image shows the X-ray diffraction spectrum of the product from Example 3.

[0030] Figure 5The image shows the X-ray diffraction spectrum of the product from Example 4.

[0031] Figure 6 This is a scanning electron microscope image of the product from Example 4.

[0032] Figure 7 The image shows the X-ray diffraction spectrum of the product from Example 5.

[0033] Figure 8 This is a scanning electron microscope image of the product from Example 5.

[0034] Figure 9 The image shows the X-ray diffraction spectrum of the product from Example 6.

[0035] Figure 10 The image shows the X-ray diffraction spectrum of the product of Comparative Example 1.

[0036] Figure 11 The image shows the X-ray diffraction spectrum of the product of Comparative Example 2.

[0037] Figure 12 The figures show the performance of photocatalytic CO2 reduction to methane (CH4) and CO for the products of Examples 1, 4, 6 and Comparative Examples 2 and 3. LDH1 is Comparative Example 2, LDH2 is Example 1, LDH3 is Example 4, LDH4 is Example 6, and LDH5 is Comparative Example 3.

[0038] Figure 13 The graphs show the selectivity of photocatalytic CO2 reduction to methane (CH4) and CO for the products of Examples 1, 4, 6 and Comparative Examples 2 and 3. LDH1 is Comparative Example 2, LDH2 is Example 1, LDH3 is Example 4, LDH4 is Example 6, and LDH5 is Comparative Example 3. Detailed Implementation

[0039] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention. It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the present invention.

[0040] Furthermore, regarding the numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any stated value or intermediate value within a stated range, as well as each smaller range between any other stated value or intermediate value within said range, are also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0041] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar to or equivalent to those described herein may be used in the implementation or testing of this invention.

[0042] The terms “comprising,” “including,” “having,” “containing,” etc., used in this invention are all open-ended terms, meaning that they include but are not limited to.

[0043] Unless otherwise specified, "room temperature" in this invention refers to 25±3℃.

[0044] All raw materials used in the following embodiments and comparative examples of the present invention are commercially available products.

[0045] Example 1

[0046] Preparation of high-entropy hydrotalcite:

[0047] (1) Crush 1g of PET plastic bottle and add it to a reaction vessel containing 50mL of 1M NaOH solution. React at 120℃ for 6h. After naturally cooling to room temperature, solution A is obtained.

[0048] (2) Prepare 10 mL of salt solution B containing 0.25 M Mg(NO3)2·6H2O, 0.25 M Co(NO3)2·6H2O, 0.25 M Ni(NO3)2·6H2O, 0.25 M Zn(NO3)2·6H2O, 0.25 M Fe(NO3)3·9H2O, and 0.25 M Al(NO3)3·6H2O;

[0049] (3) Take 40 mL of solution A and stir continuously under a high-speed magnetic stirrer. During this time, quickly pour salt solution B into solution A. Then continue stirring at room temperature for 12 h. Filter out the solid phase component, wash, and then dry at 60 °C to obtain hexa-membered high-entropy TPA intercalated hydrotalcite (denoted as TPA-Mg). 0.25 Co 0.25 Ni 0.25 Zn 0.25 Fe 0.25 Al 0.25 -LDH).

[0050] Figure 1 The image shows the X-ray diffraction spectrum of the product from Example 1. Figure 1 In the diffraction peaks at 6.3°, 12.7°, 18.8°, and 25.3°, the diffraction peaks represent the (003), (006), (009), and (015) crystal planes of the product, respectively.

[0051] Figure 2This is a scanning electron microscope (SEM) image of the product from Example 1. According to... Figure 2 As shown, the product of Example 1 is a multi-level structure composed of stacked two-dimensional nanosheets, with each nanosheet having a length and width of approximately 500 nm.

[0052] Example 2

[0053] Preparation of high-entropy hydrotalcite:

[0054] (1) Crush 1g of PET plastic bottle and add it to a reaction vessel containing 50mL of 1M NaOH solution. React at 120℃ for 6h. After naturally cooling to room temperature, solution A is obtained.

[0055] (2) Prepare 10 mL of salt solution B containing 0.5 M Mg(NO3)2·6H2O, 0.2 M Co(NO3)2·6H2O, 0.2 M Ni(NO3)2·6H2O, 0.1 M Zn(NO3)2·6H2O, 0.15 M Fe(NO3)3·9H2O, and 0.35 M Al(NO3)3·6H2O;

[0056] (3) Take 40 mL of solution A and stir continuously under a high-speed magnetic stirrer. During this time, quickly pour salt solution B into solution A. Then continue stirring at room temperature for 12 h. Filter out the solid phase component, wash, and then dry at 60 °C to obtain hexa-membered high-entropy TPA intercalated hydrotalcite (denoted as TPA-Mg). 0.5 Co 0.2 Ni 0.2 Zn 0.1 Fe 0.15 Al 0.35 -LDH).

[0057] Figure 3 The image shows the X-ray diffraction spectrum of the product from Example 2. Figure 3 In the diffraction peaks at 6.3°, 12.7°, 18.8°, and 25.3°, the diffraction peaks represent the (003), (006), (009), and (015) crystal planes of the product, respectively.

[0058] Example 3

[0059] Preparation of high-entropy hydrotalcite:

[0060] (1) Crush 1g of PET plastic bottle and add it to a reaction vessel containing 50mL of 1M NaOH solution. React at 120℃ for 6h. After naturally cooling to room temperature, solution A is obtained.

[0061] (2) Prepare 10 mL of salt solution B containing 0.5 M Mg(NO3)2·6H2O, 0.2 M Co(NO3)2·6H2O, 0.2 M Ni(NO3)2·6H2O, 0.1 M Zn(NO3)2·6H2O, 0.05 M Ce(NO3)3·6H2O, and 0.45 M Al(NO3)3·6H2O;

[0062] (3) Take 40 mL of solution A and stir continuously under a high-speed magnetic stirrer. During this time, quickly pour salt solution B into solution A. Then continue stirring at room temperature for 12 h. Filter out the solid phase component, wash, and then dry at 60 °C to obtain hexa-membered high-entropy TPA intercalated hydrotalcite (denoted as TPA-Mg). 0.5 Co 0.2 Ni 0.2 Zn 0.1 Ce 0.05 Al 0.45 -LDH).

[0063] Figure 4 The image shows the X-ray diffraction spectrum of the product from Example 3. Figure 4 In the diffraction peaks at 6.3°, 12.7°, 18.8°, and 25.3°, the diffraction peaks represent the (003), (006), (009), and (015) crystal planes of the product, respectively.

[0064] Example 4

[0065] Preparation of high-entropy hydrotalcite:

[0066] (1) 1g of PLA plastic was crushed and added to a reaction vessel containing 50mL of 1M NaOH solution. The reaction was carried out at 120℃ for 6h. After natural cooling to room temperature, solution A was obtained.

[0067] (2) Prepare 10 mL of salt solution B containing 0.25 M Mg(NO3)2·6H2O, 0.25 M Co(NO3)2·6H2O, 0.25 M Ni(NO3)2·6H2O, 0.25 M Zn(NO3)2·6H2O, 0.25 M Fe(NO3)3·9H2O, and 0.25 M Al(NO3)3·6H2O;

[0068] (3) Take 40 mL of solution A and stir continuously under a high-speed magnetic stirrer. During this time, quickly pour salt solution B into solution A. Then continue stirring at room temperature for 12 h. Filter out the solid phase component, wash, and then dry at 60 °C to obtain hexa-membered high-entropy LA intercalated hydrotalcite (denoted as LA-Mg). 0.25 Co 0.25 Ni 0.25 Zn 0.25 Fe0.25 Al 0.25 -LDH).

[0069] Figure 5 The image shows the X-ray diffraction spectrum of the product from Example 4.

[0070] Figure 6 This is a scanning electron microscope image of the product from Example 4.

[0071] Example 5

[0072] Preparation of high-entropy hydrotalcite:

[0073] (1) 1g of PBT plastic was crushed and added to a reaction vessel containing 50mL of 1M NaOH solution. The reaction was carried out at 120℃ for 6h. After natural cooling to room temperature, solution A was obtained.

[0074] (2) Prepare 10 mL of salt solution B containing 0.25 M Mg(NO3)2·6H2O, 0.25 M Co(NO3)2·6H2O, 0.25 M Ni(NO3)2·6H2O, 0.25 M Zn(NO3)2·6H2O, 0.25 M Fe(NO3)3·9H2O, and 0.25 M Al(NO3)3·6H2O;

[0075] (3) Take 40 mL of solution A and stir continuously under a high-speed magnetic stirrer. During this time, quickly pour salt solution B into solution A. Then continue stirring at room temperature for 12 h, filter out the solid phase component, wash, and then dry at 60 °C to obtain hexa-membered high-entropy TPA intercalated hydrotalcite (denoted as TPA). PBT -Mg 0.25 Co 0.25 Ni 0.25 Zn 0.25 Fe 0.25 Al 0.25 -LDH).

[0076] Figure 7 The image shows the X-ray diffraction spectrum of the product from Example 5. Figure 7 In the diffraction peaks at 6.3°, 12.7°, 18.8°, and 25.3°, the diffraction peaks represent the (003), (006), (009), and (015) crystal planes of the product, respectively.

[0077] Figure 8 The image shown is a scanning electron microscope (SEM) image of the product from Example 5.

[0078] Example 6

[0079] Preparation of high-entropy hydrotalcite:

[0080] (1) 0.4g PET, 0.3g PBT and 0.3g PLA were crushed and added to a reaction vessel containing 50mL 1M NaOH solution. The reaction was carried out at 120℃ for 6h. After natural cooling to room temperature, solution A was obtained.

[0081] (2) Prepare 10 mL of salt solution B containing 0.25 M Mg(NO3)2·6H2O, 0.25 M Co(NO3)2·6H2O, 0.25 M Ni(NO3)2·6H2O, 0.25 M Zn(NO3)2·6H2O, 0.25 M Fe(NO3)3·9H2O, and 0.25 M Al(NO3)3·6H2O;

[0082] (3) Take 40 mL of solution A and stir continuously under a high-speed magnetic stirrer. During this time, quickly pour salt solution B into solution A. Then continue stirring at room temperature for 12 h, filter out the solid phase component, wash, and then dry at 60 °C to obtain a hexa-membered high-entropy LA and TPA co-intercalated hydrotalcite (denoted as LA / TPA-Mg). 0.25 Co 0.25 Ni 0.25 Zn 0.25 Fe 0.25 Al 0.25 -LDH).

[0083] Figure 9 The image shows the X-ray diffraction spectrum of the product from Example 6. Figure 9 In the diffraction peaks at 6.3°, 12.7°, 18.8°, and 25.3°, the diffraction peaks represent the (003), (006), (009), and (015) crystal planes of the product, respectively.

[0084] Comparative Example 1 (Pure Chemical Intercalation)

[0085] Preparation of high-entropy hydrotalcite:

[0086] (1) Dissolve 0.7g of terephthalic acid in 50mL of 1M NaOH solution to obtain solution A;

[0087] (2) Prepare 10 mL of salt solution B containing 0.25 M Mg(NO3)2·6H2O, 0.25 M Co(NO3)2·6H2O, 0.25 M Ni(NO3)2·6H2O, 0.25 M Zn(NO3)2·6H2O, 0.25 M Fe(NO3)3·9H2O, and 0.25 M Al(NO3)3·6H2O;

[0088] (3) Take 40 mL of solution A and stir continuously under a high-speed magnetic stirrer. During this time, quickly pour salt solution B into solution A. Then continue stirring at room temperature for 12 h. Filter out the solid phase component, wash, and then dry at 60 °C to obtain a hexa-membered high-entropy terephthalic acid intercalated hydrotalcite (denoted as TPAcontol-Mg). 0.25 Co 0.25 Ni 0.25 Zn 0.25 Fe 0.25 Al 0.25 -LDH).

[0089] Figure 10 The image shows the X-ray diffraction spectrum of the product of Comparative Example 1. Figure 10 In the diffraction pattern, the peaks appearing at 6.3°, 12.7°, 18.8°, and 25.3° represent the (003), (006), (009), and (015) crystal planes of the product, respectively. (The text abruptly ends here.) Figure 10 It is known that hydrotalcite made from polyester plastic waste can have a crystal structure similar to that of hydrotalcite made from pure chemical terephthalic acid.

[0090] Comparative Example 2 (NO3) - Intercalation)

[0091] Preparation of high-entropy hydrotalcite:

[0092] (1) Prepare a 1M NaOH solution as solution A;

[0093] (2) Prepare 10 mL of salt solution B containing 0.25 M Mg(NO3)2·6H2O, 0.25 M Co(NO3)2·6H2O, 0.25 M Ni(NO3)2·6H2O, 0.25 M Zn(NO3)2·6H2O, 0.25 M Fe(NO3)3·9H2O, and 0.25 M Al(NO3)3·6H2O;

[0094] (3) Take 40 mL of solution A and stir continuously under a high-speed magnetic stirrer. During this process, quickly pour salt solution B into solution A. Then continue stirring at room temperature for 12 h. Filter out the solid phase component, wash, and then dry at 60 °C to obtain hexavalent high-entropy NO3. - Intercalated hydrotalcite (denoted as NO3) - -Mg 0.25 Co 0.25 Ni 0.25 Zn 0.25 Fe 0.25 Al 0.25 -LDH).

[0095] Figure 11The image shows the X-ray diffraction spectrum of the product of Comparative Example 2. Figure 11 In the diffraction peaks at 11.5°, 23.5°, 34.8°, and 39.3°, the diffraction peaks represent the (003), (006), (009), and (015) crystal planes of the product, respectively.

[0096] Comparative Example 3

[0097] Preparation of bimetallic hydrotalcite:

[0098] (1) Crush 1g of PET plastic bottle and add it to a reaction vessel containing 50mL of 1M NaOH solution. React at 120℃ for 6h. After naturally cooling to room temperature, solution A is obtained.

[0099] (2) Prepare 10 mL of salt solution B containing 1 M Co(NO3)2·6H2O and 0.5 M Al(NO3)3·6H2O;

[0100] (3) Take 40 mL of solution A and stir continuously under a high-speed magnetic stirrer. During this time, quickly pour salt solution B into solution A. Then continue stirring at room temperature for 12 h, filter out the solid phase component, wash, and then dry at 60 °C to obtain bimetallic TPA intercalated hydrotalcite (denoted as TPA-Co1Al). 0.5 -LDH).

[0101] Effect verification

[0102] The photocatalytic performance of the products from Examples 1, 4, and 6, and Comparative Examples 2 and 3 was tested. The specific test method was as follows: 30 mg of the above products were weighed and evenly spread in a 50 mL offline photocatalytic reactor, and 100 μL of deionized water was added. Industrial-grade high-purity carbon dioxide was used as the reaction atmosphere, and the reactor was irradiated with a 300 W xenon lamp at room temperature and pressure. After 5 hours of reaction, samples were taken and the gas composition was analyzed by gas chromatography. The test results are as follows: Figure 12 , 13 As shown.

[0103] Figure 12 The figures show the performance of photocatalytic CO2 reduction to methane (CH4) and CO for the products of Examples 1, 4, 6 and Comparative Examples 2 and 3. LDH1 is Comparative Example 2, LDH2 is Example 1, LDH3 is Example 4, LDH4 is Example 6, and LDH5 is Comparative Example 3.

[0104] Figure 13 The graphs show the selectivity of photocatalytic CO2 reduction to methane (CH4) and CO for the products of Examples 1, 4, 6 and Comparative Examples 2 and 3. LDH1 is Comparative Example 2, LDH2 is Example 1, LDH3 is Example 4, LDH4 is Example 6, and LDH5 is Comparative Example 3.

[0105] The results above show that, in each embodiment, the TPA or LA intercalated high-entropy LDHs relative to NO3 - High-entropy LDHs and bimetallic LDHs exhibit higher photocatalytic CO2 reduction efficiency and product selectivity. This may be because the present invention can utilize the waste alkaline solution from the alkaline hydrolysis of polyester plastics and the organic molecules of the plastic hydrolysis products to synthesize high-entropy intercalated layered double hydroxides. TPA or LA intercalation promotes the expansion of the interlayer spacing of LDHs, while the high-entropy effect caused by multiple metals effectively promotes the transfer of electrons and holes.

[0106] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. An application of high-entropy hydrotalcite in the field of photocatalytic CO2 reduction, characterized in that, The preparation method of the high-entropy hydrotalcite includes the following steps: (1) The polyester plastic is placed in an alkaline solution and reacted to obtain solution A; (2) Mix the solution A with the high-entropy metal salt and react to obtain the solid, which is the high-entropy hydrotalcite; In step (1): the amount of polyester plastic added is 20-60 g / L. -1 ; In step (2): the reaction temperature is 25-75 ℃ and the time is 12h; The high-entropy metal salt contains five or more metal salts; the metal salts include divalent metal salts and trivalent metal salts.

2. The application according to claim 1, characterized in that, In step (1): the alkaline solution is a NaOH solution.

3. The application according to claim 1, characterized in that, In step (1): the reaction temperature is 120℃ and the time is 6h.

4. The application according to claim 1, characterized in that, In step (2): the total concentration of the divalent metal salt is 0.2-0.3 M, and the total concentration of the trivalent metal salt is 0.1 M.

5. The application according to claim 1, characterized in that, The divalent metal salts include one or more of magnesium salts, calcium salts, iron salts, cobalt salts, copper salts, nickel salts, and zinc salts; the trivalent metal salts include one or more of aluminum salts, iron salts, and cerium salts.

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