A NiO x Palladium nanoparticle catalyst supported on NF, method for preparing the same and method for electrocatalyzing PET plastic

Abstract

This invention provides a NiO x A method for preparing a Ni(OH)₂ / NF supported palladium nanoparticle catalyst includes the following steps: Nickel foam (NF) is sequentially placed in hydrochloric acid solution, acetone solution, and deionized water, ultrasonicated, and dried to obtain pretreated NF; Nickel nitrate hexahydrate and hexamethylenetetramine are dissolved in deionized water, ultrasonicated until a homogeneous solution is formed, poured into a high-pressure reactor, and the pretreated NF is vertically immersed into the homogeneous solution, sealed, and subjected to a hydrothermal reaction. After removal, it is washed and dried to obtain a Ni(OH)₂ / NF intermediate with an ultrathin array of nickel hydroxide nanosheets; The obtained Ni(OH)₂ / NF intermediate is placed in a tube furnace and sintered under nitrogen conditions to obtain NiO with a porous array of nickel oxide nanosheets. x / NF precursor. The obtained NiO x The / NF precursor was placed in a palladium salt solution and reacted at a constant temperature. After removal, it was washed and dried to finally obtain NiO. x / NF supported palladium nanoparticle catalyst. This application also discloses a NiO x / NF supported palladium nanoparticle catalyst and its electrocatalytic method for PET plastics.

Description

Technical Field

[0001] This invention belongs to the field of waste plastic upgrading and conversion technology, and particularly relates to a NiO... x / NF supported palladium nanoparticle catalyst, its preparation method and its electrocatalytic method for PET plastics. Background Technology

[0002] Plastics are widely used due to their excellent performance, convenient molding and processing characteristics, and low cost. While the large-scale production and widespread application of plastics have greatly facilitated people's daily lives, they have also caused serious environmental problems. Furthermore, if petroleum-based synthetic plastic products cannot be effectively recycled and reused, it will undoubtedly lead to a serious waste of petroleum resources.

[0003] Polyethylene glycol terephthalate (PET), a type of polyester, ranks second globally in the production of thermoplastic polymers, with China ranking first. PET possesses exceptional properties, exhibiting excellent physical and mechanical properties, good electrical insulation, outstanding fatigue and abrasion resistance, and stable dimensions. These advantages make it a major component of synthetic polyester, accounting for over 80% of total synthetic fibers. Furthermore, PET is odorless and non-toxic, safe for direct contact with food-grade products, leading to its widespread use in food packaging, catering packaging, and many other fields. However, currently, most PET plastic products are used as single-use consumer goods, and once discarded, they are difficult to degrade naturally. Recycling primarily involves two methods: physical recycling and chemical recycling. During physical recycling, the simultaneous action of thermal and mechanical processing inevitably reduces the molecular weight of the recycled product, resulting in most products only being able to be downgraded and unable to be recycled multiple times. It also struggles to handle complex waste fibers. Chemical recycling, on the other hand, involves depolymerizing the long molecular chains of waste PET plastic into monomers or breaking them down into smaller organic molecules under specific chemical or biochemical conditions. These products are then purified or refined through oil and gas refining to obtain upgraded products such as raw materials. Theoretically, chemical recycling holds the promise of achieving a "closed-loop" cycle for waste plastics, which is why it has received considerable attention in both the scientific and industrial fields in recent years.

[0004] PET has the chemical formula (C 10 H8O4) nIn an alkaline environment, PET can undergo chemical hydrolysis to produce purified terephthalic acid (PTA) and ethylene glycol (EG). However, separating the products generated in this process is quite difficult. In recent years, with the aid of special chemical conditions such as light and electricity and catalysts, EG has been catalytically converted into high-value and easily separable chemicals such as glycolic acid (GA), which has become a highly promising method for high-value recycling of PET. Recent reports indicate that PET plastic can be converted into valuable formate and glycolate through photoelectrocatalysis. However, even with these advancements, the process still suffers from low space productivity and poor selectivity for single high-value oxidation products.

[0005] To solve the above-mentioned technical problems, this invention designs a NiO x / NF supported palladium nanoparticle catalyst, its preparation method and its electrocatalytic method for PET plastics. Summary of the Invention

[0006] This invention provides a NiO x / NF supported palladium nanoparticle catalysts, their preparation methods, and their electrocatalytic methods for PET plastics aim to address the problems of low space productivity and poor selectivity for single high-value oxidation products.

[0007] To achieve the above objectives, the present invention provides the following technical solution: a NiO x The preparation method of / NF supported palladium nanoparticle catalyst includes the following steps:

[0008] S1, nickel foam (NF) is placed in hydrochloric acid solution, acetone solution and deionized water in sequence and sonicated, and then placed in a vacuum drying oven to dry to obtain pretreated NF;

[0009] S2, nickel nitrate hexahydrate and hexamethylenetetramine were dissolved in deionized water and sonicated until a homogeneous solution was formed. The solution was poured into a high-pressure reactor and the pretreated NF was vertically immersed into the homogeneous solution. The reactor was sealed and subjected to a hydrothermal reaction. After the reaction was complete, the solution was cooled to room temperature, removed and washed several times with deionized water and anhydrous ethanol. Then it was placed in a vacuum drying oven to dry, thus obtaining a Ni(OH)2 / NF intermediate with an array of ultrathin nickel hydroxide nanosheets attached.

[0010] S3, the obtained Ni(OH)2 / NF intermediate was placed in a tube furnace and sintered under nitrogen atmosphere to obtain NiO with porous nickel oxide nanosheet arrays attached. x / NF precursor;

[0011] S4, the obtained NiOx The / NF precursor was placed in a palladium salt solution and reacted at a constant temperature. After removal, it was washed with deionized water and anhydrous ethanol, respectively, and then dried in a vacuum drying oven to finally obtain NiO. x / NF supported palladium nanoparticle catalyst.

[0012] Based on the above technical solution, in step S1, the concentration of hydrochloric acid solution is 1~3 mol / L, the ultrasonic time is 5~10 min, and the vacuum drying temperature is 60℃.

[0013] Based on the above technical solution, in step S2, the molar ratio of nickel nitrate hexahydrate to hexamethylenetetramine is 1:2, the hydrothermal temperature is 100~120℃, and the hydrothermal time is 10h.

[0014] Based on the above technical solution, in step S3, the sintering temperature is 300~500℃ and the sintering time is 2h.

[0015] Based on the above technical solution, in step S4, the palladium salt solution is a palladium chloride solution or a potassium tetrachloropalladate solution, and the concentration of the palladium salt solution is 5~20 mg / ml.

[0016] Secondly, the present invention provides a NiO x / NF supported palladium nanoparticle catalyst, NiO according to any one of the above embodiments x The / NF-supported palladium nanoparticle catalyst was prepared by a specific method.

[0017] Thirdly, the present invention provides a NiO x A method for electrocatalyzing PET plastics using an NF-supported palladium nanoparticle catalyst includes the following steps:

[0018] A1. PET plastic is washed and dried, then dissolved in an alkaline solution at high temperature, cooled to room temperature, and filtered to separate solid and liquid, yielding an alkaline ethylene glycol solution as the PET hydrolysis product.

[0019] A2, Assemble a flow electrolytic cell, with the working electrode being the NiO as described in claim 6. x / NF supported palladium nanoparticle catalyst, the electrolyte in the anode region is PET hydrolysis product, the electrolyte in the cathode region is potassium hydroxide solution, and the cathode region and anode region are separated by an ion exchange membrane;

[0020] A3 involves heating a flow-through electrolytic cell and applying voltage to it. The PET hydrolysis products in the anolyte undergo electrocatalytic oxidation, and glycolic acid is obtained after the reaction is complete.

[0021] Based on the above technical solution, in step A1, the alkaline solution is a potassium hydroxide solution or a sodium hydroxide solution, the concentration of the alkaline solution is 3~10 mol / L, the dissolution temperature is 80~120℃, the dissolution time is 12~72h, and the pH is adjusted to 1~3.

[0022] Based on the above technical solution, in step A2, the cathode electrode is Ni2P / NF obtained by phosphating the Ni(OH)2 / NF intermediate obtained in step S2 in a tube furnace. During the phosphating process, sodium hypophosphite powder is placed at one end of the steam inlet, and the Ni(OH)2 / NF intermediate is placed at the other end. Sintering is carried out under a nitrogen atmosphere at a sintering temperature of 300~400℃ and a sintering time of 2~3h. The concentration of ethylene glycol solution in the electrolyte in the anode region is 320~1000mmol / L, and the concentration of potassium hydroxide solution is 1~10mol / L.

[0023] Based on the above technical solution, in step A3, the heating temperature is 25~60℃, the applied voltage range is 0.4~1.3V vs. RHE, and the electrocatalytic oxidation reaction time is 0.5h~300h.

[0024] Compared with related technologies, the beneficial effects of the present invention are as follows:

[0025] 1. This invention synthesizes NiO using a simple method. x / NF-supported palladium nanoparticle catalyst Pd-NiO x / NF, this catalyst has the advantages of large specific surface area, low Pd loading and high activity. In the catalytic process, this material can provide more active sites and increase its contact range with reactants, thereby significantly improving catalytic activity and providing a highly efficient and inexpensive electrocatalyst for the electrocatalytic oxidation of PET.

[0026] 2. The Pd-NiO synthesized in this invention x NiO is introduced into the / NF catalyst x As an oxophilic compound, it can modulate the electronic structure of palladium, thereby altering the adsorption of carbonyl intermediates on the material surface, and NiO x The presence of these substances promotes the formation of hydroxyl radicals. The synergistic effect of these two substances not only improves the selectivity of the catalyst but also increases the material's resistance to poisoning, thereby improving the electrocatalytic oxidation process of PET and increasing the reaction rate.

[0027] 3. The material preparation method provided by this invention is simple and easy to implement, the required raw materials are readily available, and the preparation process is environmentally friendly and green. In the field of electrocatalytic oxidation of PET, this method has significant application value and broad application prospects, and is suitable for industrial production. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only one embodiment of the present invention. For those skilled in the art, other embodiments can be derived from the provided drawings without creative effort.

[0029] Figure 1 The NiO provided by this invention x Flowchart of the preparation method of / NF supported palladium nanoparticle catalyst.

[0030] Figure 2 The NiO provided by this invention x Flowchart of a method for electrocatalyzing PET plastics using / NF-supported palladium nanoparticle catalysts.

[0031] Figure 3 The Pd obtained in Example 1 of this invention 1.0 -NiO x Scanning electron microscope image of / NF.

[0032] Figure 4 It is the Pd scraped off from the catalyst in Example 1 of this invention. 1.0 -NiO x High-resolution transmission electron microscope image.

[0033] Figure 5 These are Pd-NiO with different palladium contents prepared in Examples 1-4 of this invention. x Current density curves for EG oxidation process using / NF catalyst.

[0034] Figure 6 Pd in ​​Embodiment 5 and Comparative Example 1 of the present invention 1.0 -NiO x Linear sweep voltammetric curves of EG oxidation and conventional oxygen evolution reaction using / NF catalysts.

[0035] Figure 7 Pd in ​​Embodiment 5 of the present invention 1.0 -NiO x / NF catalyst proton NMR spectra under different charge passages.

[0036] Figure 8 Pd in ​​Embodiment 5 of the present invention 1.0 -NiO x Bar chart of the Faraday efficiency of / NF catalyst for glycolic acid under different charge passage conditions.

[0037] Figure 9These are the 1H NMR spectra of the PET hydrolysis products before and after electrocatalysis in Example 6 of this invention.

[0038] Figure 10 Pd in ​​Embodiment 6 of the present invention 1.0 -NiO x / NF catalyst electrocatalytic PET hydrolysis products time-current curve. Detailed Implementation

[0039] The present invention will be further described below with reference to the accompanying drawings and examples:

[0040] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0041] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0042] In the description of this invention, it should be understood that the terms "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0043] Unless otherwise specified, the experimental methods used in the following examples are conventional methods.

[0044] Unless otherwise specified, all materials and reagents used in the following examples are commercially available.

[0045] This invention provides a NiO x The preparation method of / NF supported palladium nanoparticle catalyst includes the following steps:

[0046] S1, nickel foam (NF) is placed in hydrochloric acid solution, acetone solution and deionized water in sequence and sonicated, and then placed in a vacuum drying oven to dry to obtain pretreated NF;

[0047] S2, nickel nitrate hexahydrate and hexamethylenetetramine were dissolved in deionized water and sonicated until a homogeneous solution was formed. The solution was poured into a high-pressure reactor and the pretreated NF was vertically immersed into the homogeneous solution. The reactor was sealed and subjected to a hydrothermal reaction. After the reaction was complete, the solution was cooled to room temperature, removed and washed several times with deionized water and anhydrous ethanol. Then it was placed in a vacuum drying oven to dry, thus obtaining a Ni(OH)2 / NF intermediate with an array of ultrathin nickel hydroxide nanosheets attached.

[0048] S3, the obtained Ni(OH)2 / NF intermediate was placed in a tube furnace and sintered under nitrogen atmosphere to obtain NiO with porous nickel oxide nanosheet arrays attached. x / NF precursor;

[0049] S4, the obtained NiO x The / NF precursor was placed in a palladium salt solution and reacted at a constant temperature. After removal, it was washed with deionized water and anhydrous ethanol, respectively, and then dried in a vacuum drying oven to finally obtain NiO. x / NF supported palladium nanoparticle catalyst.

[0050] Based on the above technical solution, in step S1, the concentration of the hydrochloric acid solution is 1~3 mol / L, the ultrasonic time is 5~10 min, and the vacuum drying temperature is 60℃. Preferably, the concentration of the hydrochloric acid solution is 1 mol / L, and the ultrasonic time is 10 min.

[0051] Based on the above technical solution, in step S2, the molar ratio of nickel nitrate hexahydrate to hexamethylenetetramine is 1:2, the hydrothermal temperature is 100~120℃, and the hydrothermal time is 10h. Preferably, the hydrothermal temperature is 100℃.

[0052] Based on the above technical solution, in step S3, the sintering temperature is 300~500℃, and the sintering time is 2h. Preferably, the sintering temperature is 400℃.

[0053] Based on the above technical solution, in step S4, the palladium salt solution is a palladium chloride solution or a potassium tetrachloropalladate solution, and the concentration of the palladium salt solution is 5~20 mg / ml. Preferably, the palladium salt concentration is 10 mg / ml.

[0054] Secondly, the present invention provides a NiO x / NF supported palladium nanoparticle catalyst, NiO according to any one of the above embodiments x The / NF-supported palladium nanoparticle catalyst was prepared by a specific method.

[0055] Thirdly, the present invention provides a NiO x A method for electrocatalyzing PET plastics using an NF-supported palladium nanoparticle catalyst includes the following steps:

[0056] A1. PET plastic is washed and dried, then dissolved in an alkaline solution at high temperature, cooled to room temperature, and filtered to separate solid and liquid, yielding an alkaline ethylene glycol solution as the PET hydrolysis product.

[0057] A2, Assemble a flow-type electrolytic cell, with the working electrode being the NiO described in the above embodiments. x / NF supported palladium nanoparticle catalyst, the electrolyte in the anode region is PET hydrolysis product, the electrolyte in the cathode region is potassium hydroxide solution, and the cathode region and anode region are separated by an ion exchange membrane;

[0058] A3 involves heating a flow-through electrolytic cell and applying voltage to it. The PET hydrolysis products in the anolyte undergo electrocatalytic oxidation, and glycolic acid is obtained after the reaction is complete.

[0059] Based on the above technical solution, in step A1, the alkaline solution is a potassium hydroxide solution or a sodium hydroxide solution, the concentration of the alkaline solution is 3~10 mol / L, the dissolution temperature is 80~120℃, the dissolution time is 12~72h, and the pH is adjusted to 1~3. Preferably, the concentration of the alkaline solution is 5 mol / L, the dissolution temperature is 80℃, the dissolution time is 24h, and the pH is adjusted to 2.

[0060] Based on the above technical solution, in step A2, the cathode electrode is Ni2P / NF obtained by phosphating the Ni(OH)2 / NF intermediate obtained in step S2 in a tube furnace. During the phosphating process, sodium hypophosphite powder is placed at one end of the steam inlet, and the Ni(OH)2 / NF intermediate is placed at the other end. Sintering is carried out under a nitrogen atmosphere at a sintering temperature of 300-400℃ for 2-3 hours. The concentration of ethylene glycol solution in the electrolyte in the anode region is 320-1000 mmol / L, and the concentration of potassium hydroxide solution is 1-10 mol / L. Preferably, the sintering temperature is 300℃, the sintering time is 2 hours, the concentration of ethylene glycol solution is 1000 mmol / L, and the concentration of potassium hydroxide solution is 1 mol / L.

[0061] Based on the above technical solution, in step A3, the heating temperature is 25~60℃, the applied voltage range is 0.4~1.3V vs. RHE, and the electrocatalytic oxidation reaction time is 0.5h~300h. Preferably, the heating temperature is 60℃ and the applied voltage is 1.2V.

[0062] This invention synthesizes NiO using a simple method. x / NF-supported palladium nanoparticle catalyst Pd-NiO x / NF catalyst has the advantages of large specific surface area, low Pd loading and high activity. In the catalytic process, the material can provide more active sites and increase its contact range with reactants, thereby significantly improving catalytic activity. It provides a highly efficient and inexpensive electrocatalyst for the electrocatalytic oxidation of PET.

[0063] The Pd-NiO synthesized in this invention x NiO is introduced into the / NF catalyst x As an oxophilic compound, it can modulate the electronic structure of palladium, thereby altering the adsorption of carbonyl intermediates on the material surface, and NiO x The presence of these substances promotes the formation of hydroxyl radicals. The synergistic effect of these substances not only improves the selectivity of the catalyst but also increases the material's resistance to poisoning, thereby improving the electrocatalytic oxidation process of PET and increasing the reaction rate.

[0064] The material preparation method provided by this invention is simple and easy to implement, the required raw materials are readily available, and the preparation process is environmentally friendly. In the field of electrocatalytic oxidation of PET, this method has significant application value and broad application prospects, and is suitable for industrial production.

[0065] Example 1

[0066] like Figure 1 As shown, this disclosure provides a NiO embodiment. x The preparation method of / NF supported palladium nanoparticle catalyst includes the following steps:

[0067] S1. A piece of nickel foam (NF) with dimensions of 2cm*3cm*1.6mm was placed in 1mol / L hydrochloric acid solution, 1mol / L acetone solution and deionized water and sonicated for 10min. Then it was placed in a vacuum drying oven and dried at 60℃ for 12h to obtain pretreated NF.

[0068] S2, 1.09 g of nickel nitrate hexahydrate and 1.05 g of hexamethylenetetramine were dissolved in 30 mL of deionized water and sonicated until a homogeneous solution was formed. The solution was poured into a high-pressure reactor, and the pretreated NF was vertically immersed into the homogeneous solution. The reactor was sealed and hydrothermally reacted at 100 °C for 10 h. After the reaction was complete, the reactor was cooled to room temperature. The reacted NF was taken out and washed three times with deionized water and anhydrous ethanol, respectively. Then it was placed in a vacuum drying oven at 60 °C and dried for 12 h to obtain a Ni(OH)2 / NF intermediate with an array of ultrathin nickel hydroxide nanosheets attached.

[0069] S3, the obtained Ni(OH)2 / NF intermediate was placed in a tube furnace and sintered under nitrogen atmosphere for 2 hours at 400°C to obtain NiO with porous nickel oxide nanosheet arrays attached. x / NF precursor;

[0070] S4, the obtained NiO x / NF precursor was cut into 1cm*2cm square pieces and placed vertically in 200mL of 10mg / mL palladium chloride solution. The mixture was kept at 28℃ for 2 hours, then washed three times each with deionized water and anhydrous ethanol. Finally, it was dried in a vacuum drying oven at 60℃ for 12 hours, yielding a final palladium content of 1.0mg / cm³. 2 NiO x / NF-supported palladium nanoparticle catalyst Pd 1.0 -NiO x / NF.

[0071] Example 2

[0072] The preparation method in this embodiment is the same as that in Example 1, with the identical parts omitted. The difference from Example 1 is that in this embodiment, the concentration of the palladium chloride solution or potassium tetrachloropalladate solution is 5 mg / mL, resulting in a palladium content of 0.5 mg / mL. 2 NiO x / NF-supported palladium nanoparticle catalyst Pd 0.5 -NiO x / NF.

[0073] Example 3

[0074] The preparation method in this embodiment is the same as that in Example 1, with the identical parts omitted. The difference from Example 1 is that in this embodiment, the concentration of the palladium chloride solution or potassium tetrachloropalladate solution is 15 mg / mL, resulting in a palladium content of 1.5 mg / mL. 2 NiO x / NF-supported palladium nanoparticle catalyst Pd 1.5 -NiO x / NF.

[0075] Example 4

[0076] The preparation method in this embodiment is the same as that in Example 1, with the identical parts omitted. The difference from Example 1 is that in this embodiment, the concentration of the palladium chloride solution or potassium tetrachloropalladate solution is 20 mg / mL, resulting in a palladium content of 2.0 mg / mL. 2 NiO x / NF-supported palladium nanoparticle catalyst Pd 2.0 -NiO x / NF.

[0077] Example 5

[0078] A three-electrode system was used to carry out catalytic oxidation in an electrolytic cell, with the palladium content obtained in Example 1 being 1 mg / cm³. 2 NiOx / NF-supported palladium nanoparticle catalyst was used as the working electrode, Ag / AgCl as the reference electrode, and a platinum sheet as the counter electrode, with a volume ratio of 18:1 and 1 mol·L⁻¹. -1 potassium hydroxide solution and 1 mol·L -1 A mixture of ethylene glycol and ethylene glycol solutions serves as the electrolyte, together forming the electrocatalytic reactor. Linear sweep voltammetric characteristics were tested at room temperature and pressure under conditions of 0.4–1.3 V vs. RHE, with continuous stirring during the reaction at a constant voltage of 0.8 V vs. RHE.

[0079] Comparative Example 1

[0080] The preparation method in this embodiment is the same as that in Example 5, and the identical parts are omitted. The difference from Example 5 is that in this embodiment, the electrolyte is 1 mol·L⁻¹. -1 A potassium hydroxide solution, with a voltage range of 0.4~2.0V vs. RHE.

[0081] Example 6

[0082] like Figure 2 As shown, this disclosure provides a NiO embodiment. x A method for electrocatalyzing PET plastics using an NF-supported palladium nanoparticle catalyst includes the following steps:

[0083] A1. 10g of PET plastic was washed and dried, then placed in an alkaline potassium hydroxide solution and heated to 80℃ by oil bath reflux for 24h. After cooling to room temperature, solid-liquid separation was performed by vacuum filtration to obtain an ethylene glycol solution and potassium terephthalate precipitate. The potassium terephthalate precipitate was washed with deionized water and acidified with 12mol / L hydrochloric acid to obtain terephthalic acid. The resulting mixed solution of ethylene glycol and potassium hydroxide was used as the PET hydrolysis product.

[0084] A2, Assemble a flow electrolytic cell, with the working electrode being the palladium content obtained in Example 1 at 1 mg / cm³. 2 NiO x / NF supported palladium nanoparticle catalyst, the cathode electrode is Ni2P / NF obtained by phosphating the Ni(OH)2 / NF intermediate obtained in step S2 of Example 1 at 300°C in a tube furnace, the electrolyte in the anode region is PET hydrolysis product, the electrolyte in the cathode region is potassium hydroxide solution, and the cathode region and anode region are separated by an ion exchange membrane.

[0085] A3, a flow electrolytic cell was heated at 60°C and a voltage of 1.2V was applied to the electrolytic cell. The PET hydrolysis products in the anolyte were subjected to electrocatalytic oxidation for 250 hours. After the reaction was completed, glycolic acid was obtained.

[0086] Figure 3 The Pd obtained in Example 1 of this invention 1.0 -NiO x Scanning electron microscopy images of / NF show that it has a distinct coral-like structure and good contact with the substrate, which provides the possibility of increasing conductivity and exposing more active sites.

[0087] Figure 4 The Pd scraped off from the catalyst in Example 1 of this invention 1.0 -NiO x The high-resolution transmission electron microscope images show that it exhibits different interplanar spacings and clearly distinguishes between Pd and NiO. x The crystal structure is shown. Simultaneously, lattice bending can be observed, indicating an interaction between Pd and the NF substrate, providing a basis for improving activity and selectivity.

[0088] Figure 5 These are Pd-NiO with different palladium contents prepared in Examples 1-4 of this invention. x The current density curve of Pd-NiO during the EG oxidation process using / NF catalyst clearly shows that Pd-NiO x / NF catalyst at a palladium content of 1 mg / cm 2 At that time, EG exhibits the best electrocatalytic oxidation performance.

[0089] Figure 6 Pd in ​​Embodiment 5 and Comparative Example 1 of the present invention 1.0 -NiO x Linear sweep voltammetric curves of the EG oxidation process and the conventional oxygen evolution reaction were obtained using the / NF catalyst. In comparison, at the same current density, the Pd-NiO catalyst in the EG oxidation process... x / NF catalysts require lower potentials and exhibit good potential for PET electrocatalysis.

[0090] Figure 7 Pd in ​​Embodiment 5 of the present invention 1.0 -NiO x The 1H NMR spectra of the / NF catalyst under different charge passages describe the dynamic process of EG to GA oxidation. It can be found that as the charge increases, the content of EG gradually decreases and the content of GA gradually increases.

[0091] Figure 8 Pd in ​​Embodiment 5 of the present invention 1.0 -NiO x The bar chart of the Faraday efficiency of the / NF catalyst for glycolic acid under different charge passages shows that the Faraday efficiency of glycolic acid remained above 90% throughout the entire electrocatalytic process, indicating that the Pd-NiO catalyst... x / NF catalysts exhibit high selectivity.

[0092] Figure 9 These are the 1H NMR spectra of the PET hydrolysis products before and after electrocatalysis in Example 6 of this invention. The results show that the content of EG decreases and the content of GA increases after electrocatalysis of the PET hydrolysis products.

[0093] Figure 10 Pd in ​​Embodiment 6 of the present invention 1.0 -NiO x The time-current curve of NF catalyst electrocatalyzing PET hydrolysis products shows that the PET hydrolysis products were electrocatalyzed using a constant voltage method. Under the condition of 1.2V voltage, the electrolyte flow rate in the anode and cathode regions was 40ml / min. The PET hydrolysis products were completely electrolyzed within 250h to obtain glycolic acid solution with a yield of 50.2%. The yield is the ratio of the amount of glycolic acid actually obtained by electrolysis of the same mass of PET to the amount of glycolic acid theoretically produced.

[0094] The present invention has been described above by way of example, but the present invention is not limited to the specific embodiments described above. Any modifications or variations made based on the present invention shall fall within the scope of protection claimed by the present invention.

Claims

1. A NiO x The method for preparing / NF supported palladium nanoparticle catalysts is characterized by, Includes the following steps: S1, nickel foam (NF) was placed in 1-3 mol / L hydrochloric acid solution, acetone solution and deionized water and sonicated for 5-10 min, and then dried in a vacuum drying oven at 60℃ to obtain pretreated NF; S2, nickel nitrate hexahydrate and hexamethylenetetramine were dissolved in deionized water at a molar ratio of 1:2, and sonicated until a homogeneous solution was formed. The solution was poured into a high-pressure reactor, and the pretreated NF was vertically immersed into the homogeneous solution. The hydrothermal reaction was carried out at 100~120℃ for 10h. After the reaction was complete, the solution was cooled to room temperature, removed and washed several times with deionized water and anhydrous ethanol. Then it was placed in a vacuum drying oven to dry, and Ni(OH)2 / NF intermediate with an ultrathin nickel hydroxide nanosheet array was obtained. S3, the obtained Ni(OH)2 / NF intermediate was placed in a tube furnace and sintered at 300~500℃ for 2 hours under nitrogen atmosphere to obtain NiO with porous nickel oxide nanosheet arrays attached. x / NF precursor; S4, the obtained NiO x The / NF precursor was placed in a palladium salt solution with a concentration of 5-20 mg / ml and reacted at a constant temperature. After removal, it was washed with deionized water and anhydrous ethanol, respectively, and then dried in a vacuum drying oven to finally obtain NiO. x / NF supported palladium nanoparticle catalyst.

2. A NiO x A method for electrocatalyzing PET plastics using an NF-supported palladium nanoparticle catalyst, characterized in that... Includes the following steps: A1. PET plastic is washed and dried, then dissolved in an alkaline solution at high temperature, cooled to room temperature, and filtered to separate solid and liquid, yielding an alkaline ethylene glycol solution as the PET hydrolysis product. A2, Assemble a flow electrolytic cell, with the working electrode being the NiO as described in claim 1. x / NF supported palladium nanoparticle catalyst, the electrolyte in the anode region is PET hydrolysis product, the electrolyte in the cathode region is potassium hydroxide solution, and the cathode region and anode region are separated by an ion exchange membrane; A3 involves heating a flow-through electrolytic cell and applying voltage to it. The PET hydrolysis products in the anolyte undergo electrocatalytic oxidation, and glycolic acid is obtained after the reaction is complete.

3. The NiO according to claim 2 x A method for electrocatalyzing PET plastics using an NF-supported palladium nanoparticle catalyst, characterized in that... In step A1, the alkaline solution is a potassium hydroxide solution or a sodium hydroxide solution, the concentration of the alkaline solution is 3~10 mol / L, the dissolution temperature is 80~120℃, the dissolution time is 12~72h, and the pH is adjusted to 1~3.

4. The NiO according to claim 2 x A method for electrocatalyzing PET plastics using an NF-supported palladium nanoparticle catalyst, characterized in that... In step A2, the cathode electrode is Ni2P / NF obtained by phosphating the Ni(OH)2 / NF intermediate obtained in step S2 in a tube furnace. During the phosphating process, sodium hypophosphite powder is placed at one end of the steam inlet, and the Ni(OH)2 / NF intermediate is placed at the other end. Sintering is carried out under a nitrogen atmosphere at a sintering temperature of 300~400℃ for 2~3h. The concentration of ethylene glycol solution in the electrolyte in the anode region is 320~1000mmol / L, and the concentration of potassium hydroxide solution is 1~10mol / L.

5. The NiO according to claim 2 x A method for electrocatalyzing PET plastics using an NF-supported palladium nanoparticle catalyst, characterized in that... In step A3, the heating temperature is 25~60℃, the applied voltage range is 0.4~1.3V vs. RHE, and the electrocatalytic oxidation reaction time is 0.5h~300h.

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