Method for photocatalytic degradation of polyesters

Abstract

The application relates to the field of catalytic material preparation, and discloses a method for photocatalytic degradation of polyester. The method comprises the following steps: performing a photocatalytic degradation reaction on polyester and a catalyst in the presence of a solvent; wherein the catalyst comprises a metal organic framework material and optionally a binder. The method can improve the conversion rate of photocatalytic degradation of polyester.

Description

Technical Field

[0001] This invention relates to the field of catalytic material preparation, and more specifically to a method for photocatalytic degradation of polyester. Background Technology

[0002] Currently, my country produces approximately 79 million tons of polyester annually, of which 80% is discarded, resulting in enormous economic and resource waste. Plastic additives continue to be released into the environment as they age and decompose, causing immeasurable and lasting environmental impacts. Therefore, recycling polyester to produce high-value-added chemicals is an important development direction for resource recycling and safeguarding human health.

[0003] The literature [Chemical Engineering Journal 454(2023)140377] reports a photocatalytic polyester degradation method using Fe2O3 / g-C3N4 as a catalyst. Under illumination conditions in the wavelength range of 200 nm to 800 nm, the polyester conversion rate reaches 64% after 125 hours of reaction, which is low.

[0004] Therefore, there is an urgent need to study methods that can maintain a high polyester conversion rate. Summary of the Invention

[0005] The purpose of this invention is to overcome the problem of low conversion rate of photocatalytic degradation of polyester in the prior art, and to provide a method for photocatalytic degradation of polyester that can improve the conversion rate of photocatalytic degradation of polyester.

[0006] To achieve the above objectives, a first aspect of the present invention provides a method for photocatalytic degradation of polyester, wherein the method includes the following steps:

[0007] In the presence of a solvent, polyester is subjected to a photocatalytic degradation reaction with a catalyst;

[0008] The catalyst includes a metal-organic framework material and optionally a binder.

[0009] Preferably, the conditions for the photocatalytic degradation reaction include: an operating temperature of 10–300°C, preferably 25–300°C; an operating pressure of 0.1–10 MPa, preferably 1–5 MPa; and a light source density of 100–1500 mW / cm³. 2 The wavelength of the light source is 200-800nm.

[0010] Preferably, the polyester is selected from at least one of polyethylene terephthalate, polybutylene terephthalate, and polyarylate, and is preferably polyethylene terephthalate.

[0011] Preferably, the mass ratio of catalyst to polyester is 1:5-100.

[0012] Preferably, the metal in the metal-organic framework material is selected from at least one of Fe, Zr, Hf, Al, Sr and Cr, and more preferably Fe.

[0013] Preferably, the organic ligand in the metal-organic framework material is selected from terephthalic acid and its derivatives, and more preferably at least one of terephthalic acid, 2-aminoterephthalic acid, 2,4-diaminoterephthalic acid, 2-hydroxyterephthalic acid, 2,4-dihydroxyterephthalic acid, 2-carboxyterephthalic acid and 2,4-dicarboxyterephthalic acid, and more preferably at least one of terephthalic acid, 2-aminoterephthalic acid and 2,4-diaminoterephthalic acid.

[0014] Preferably, Fe is present in the metal-organic framework material. II and Fe III Two forms, of which Fe II Fe III The ratio is 1:100 to 100:1, preferably 1:4 to 4:1, and more preferably 1:2 to 2:1.

[0015] The photocatalytic degradation method for polyester provided by this invention, through the use of metal-organic frameworks (MOFs) as catalysts, can improve the conversion rate of polyester. MOFs possess excellent photocatalytic performance and tunable structural characteristics, effectively promoting the decomposition of polyester molecules. Simultaneously, this method utilizes light energy as the primary driving force, reducing energy consumption and environmental pollution. This method exhibits good degradation effects on various polyester types, demonstrating strong adaptability. Furthermore, with the assistance of solvents, the reaction can be carried out under mild conditions, eliminating the need for extreme operations and simplifying the process. Attached Figure Description

[0016] Figure 1 These are scanning electron microscope (SEM) images of the metal-organic framework material in Example 1;

[0017] Figure 2 The image shows the X-ray diffraction (XRD) curve of the metal-organic framework material in Example 1. Detailed Implementation

[0018] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0019] Unless otherwise specified, all percentages, parts, ratios, etc. mentioned in this invention are based on weight, unless being based on weight would not be in accordance with the common understanding of those skilled in the art.

[0020] In this invention, unless otherwise stated, room temperature or normal temperature refers to 25±2℃.

[0021] In this invention, unless otherwise stated, all pressures are gauge pressures.

[0022] In this invention, unless otherwise specified, the unit of light source density is mW / cm². 2 This refers to milliwatts per cubic centimeter.

[0023] The first aspect of this invention provides a method for photocatalytic degradation of polyester, wherein the method includes the following steps:

[0024] In the presence of a solvent, polyester is subjected to a photocatalytic degradation reaction with a catalyst;

[0025] The catalyst includes a metal-organic framework material and optionally a binder.

[0026] The photocatalytic degradation method for polyester provided by this invention utilizes metal-organic frameworks (MOFs) as catalysts. MOFs possess excellent photocatalytic performance and tunable structural characteristics, effectively promoting the decomposition of polyester molecules and improving the efficiency of photocatalytic degradation. Simultaneously, this method utilizes light energy as the primary driving force, reducing energy consumption and environmental pollution. This method exhibits good degradation effects on various polyester types, demonstrating strong adaptability. Furthermore, with the assistance of solvents, the reaction can proceed under mild conditions, eliminating the need for extreme operations and simplifying the process. By adjusting the catalyst composition or adding binders, reaction conditions can be further optimized, enhancing catalytic performance and stability.

[0027] It should be noted that, optionally, the catalyst in this invention may include a metal-organic framework material and a binder, or may include only a metal-organic framework material. In a preferred embodiment of this invention, the catalyst includes a metal-organic framework material and a binder.

[0028] According to the present invention, preferably, the mass ratio of catalyst to polyester is 1:5-100, more preferably 1:5-30, for example, it can be 1:5, 1:8, 1:10, 1:12, 1:15, 1:18, 1:20, 1:22, 1:25, 1:28, 1:30, and any value within any range of any two values, and even more preferably 1:10-12. Using the above preferred range is more conducive to the contact between polyester and catalyst, thereby improving the conversion rate of polyester.

[0029] According to the present invention, preferably, the polyester is selected from at least one of polyethylene terephthalate, polybutylene terephthalate, and polyarylates, and more preferably polyethylene terephthalate. Using the above-mentioned preferred range is more conducive to the photocatalytic degradation of the polyester.

[0030] The present invention does not particularly limit the type of solvent, as long as it can meet the reaction requirements. Those skilled in the art can select according to actual needs. Preferably, the solvent is selected from at least one of water, alcohol compounds and organic acids, and more preferably at least one of water, methanol, ethanol, ethylene glycol, oxalic acid and isopropanol.

[0031] This invention allows for a wide range of selections of alcohol compounds. Preferably, the alcohol compounds are selected from C1-C5 alcohols. The alcohols can be monohydric or dihydric alcohols. For example, they can be methanol, ethanol, butanol, ethylene glycol, propylene glycol, butanediol, or isopropanol.

[0032] This invention allows for a wide range of organic acid selection. Preferably, the organic acid is selected from C1-C5 organic acids. The organic acid can be a monoprotic or diprotic organic acid. Examples include formic acid, acetic acid, propionic acid, oxalic acid, and malonic acid.

[0033] The present invention does not have a particular limitation on the amount of solvent used, as long as it can react with photogenerated charge carriers to generate active free radicals. Those skilled in the art can select according to actual needs. According to a specific embodiment of the present invention, preferably, the mass ratio of polyester to solvent is 1:5-100, more preferably 1:5-50.

[0034] According to the present invention, preferably, the conditions for the photocatalytic degradation reaction include: an operating temperature of 10–300°C, more preferably 25–300°C; an operating pressure of 0.1–10 MPa, more preferably 1–5 MPa; and a light source density of 100–1500 mW / cm². 2 More preferably 750-1500 mW / cm 2 The wavelength of the light source is 200-800 nm. Using the above-mentioned preferred range is more conducive to the photocatalytic degradation reaction and the improvement of polyester conversion rate.

[0035] The present invention does not particularly limit the source of light, as long as it is within the range of light source density. Those skilled in the art can select according to actual needs. Preferably, it can be a xenon lamp or an LED lamp.

[0036] According to the present invention, the range of metals selected for the metal-organic framework material is relatively wide, as long as they can be used to prepare the metal-organic framework material. Preferably, the metal in the metal-organic framework material is selected from at least one of Fe, Zr, Hf, Al, Sr and Cr, and more preferably Fe.

[0037] According to a preferred embodiment of the present invention, the metal-organic framework material is at least one of MIL-101(Fe), MIL-53(Fe), and MIL-88(Fe). The above-mentioned structure of the metal-organic framework material can be confirmed by XRD. The confirmation of the structures of MIL-101(Fe), MIL-53(Fe), and MIL-88(Fe) is well known to those skilled in the art and will not be described in detail here.

[0038] According to a preferred embodiment of the present invention, Fe is present in the metal-organic framework material. II and Fe III Two forms, of which Fe II Fe III The ratio is 1:100 to 100:1, preferably 1:4 to 4:1, and more preferably 1:2 to 2:1. This preferred embodiment is more conducive to the exposure of active sites and the stability of the framework structure.

[0039] In this invention, Fe II This refers to ferrous iron, Fe. III This refers to ferric iron (Fe3+). II and Fe III The presence and ratio of Fe2p were determined by XPS characterization; specifically, Fe2p orbitals in high-resolution Fe2p orbital XPS spectra were detected using X-ray photoelectron spectroscopy. 1 / 2 and Fe 2p 3 / 2 The presence of the peak proves that Fe II and Fe III The presence of Fe; calculated in high-resolution Fe 2p orbital XPS spectra. II and Fe III The corresponding peak area S FeII and S FeIII Calculate S FeII / S FeIII Fe II and Fe III The ratio of .

[0040] The present invention allows for a wide range of selections of organic ligands in the metal-organic framework material. Preferably, the organic ligands in the metal-organic framework material are selected from terephthalic acid and its derivatives, more preferably at least one of terephthalic acid, 2-aminoterephthalic acid, 2,4-diaminoterephthalic acid, 2-hydroxyterephthalic acid, 2,4-dihydroxyterephthalic acid, 2-carboxyterephthalic acid, and 2,4-dicarboxyterephthalic acid, and more preferably at least one of terephthalic acid, 2-aminoterephthalic acid, and 2,4-diaminoterephthalic acid, and even more preferably terephthalic acid and / or 2-aminoterephthalic acid.

[0041] The present invention does not particularly limit the morphology of the metal-organic framework material, as long as more active sites can be exposed. Those skilled in the art can select according to actual needs. Preferably, the metal-organic framework material has an octahedral aggregate morphology.

[0042] The metal-organic framework material of the above-mentioned preferred embodiment adopted in this invention has an octahedral morphology, which can increase the contact area with reactants and improve the polyester conversion rate.

[0043] According to the present invention, preferably, the octahedral aggregate is obtained by the aggregation of microspheres.

[0044] The metal-organic framework material using the above-mentioned preferred scheme has octahedral aggregates obtained by the aggregation of microspheres, which can expose more active sites, increase the contact area between active sites and reactants, enhance reactant adsorption, and under light irradiation, the metal-organic framework material generates photogenerated charge carriers. The photogenerated charge carriers react with the solvent to generate active free radicals. These active free radicals attack the carbonyl groups in the polyester, thereby achieving polyester degradation and further improving the polyester conversion rate.

[0045] According to the present invention, preferably, the edge length of the regular octahedral aggregate is 0.5 to 2 μm, more preferably 1 to 1.5 μm, and even more preferably 1 to 1.2 μm.

[0046] According to the present invention, preferably, the diameter of the microspheres is 20-100 nm, more preferably 40-80 nm, and even more preferably 50-60 nm.

[0047] Using the edge length and diameter within the above-mentioned preferred range is more conducive to exposing more active sites, increasing the contact area between active sites and reactants, enhancing reactant adsorption, and improving polyester conversion rate.

[0048] According to the present invention, preferably, the specific surface area of ​​the metal-organic framework material is 50-500 cm². 2 / g, preferably 300-500cm 2 / g, more preferably 400-500cm 2 / g. The specific surface area described in this invention was obtained by nitrogen adsorption-desorption experiment. The method for testing specific surface area is well known to those skilled in the art, and will not be described in detail here.

[0049] In this invention, the term "regular octahedron" has a broad meaning, including both regular octahedrons and quasi-regular octahedrons.

[0050] In this invention, the term "octahedral aggregate obtained by microsphere aggregation" has a broad meaning, and it is not required that all primary particles be microspheres. A scheme in which more than 90% of the primary particles are microspheres is also within the scope of protection of this invention.

[0051] In this invention, the octahedral aggregate obtained by microsphere aggregation means that the metal-organic framework material has secondary particles formed by the aggregation of primary microsphere particles, and the secondary particles are in the shape of octahedrons.

[0052] In this invention, the morphology of the metal-organic framework material, the edge length of the octahedral aggregates, and the diameter of the microspheres are obtained by SEM characterization. Specifically, the edge length of the octahedral aggregates and the diameter of the microspheres in 50 different regions of the material are statistically analyzed using 20 SEM images, and then the average value is calculated.

[0053] According to the present invention, preferably, based on the total amount of catalyst, the content of the metal-organic framework material is 55-98% by weight, more preferably 60-95% by weight, and even more preferably 65-80% by weight; the content of the binder is 2-45% by weight, more preferably 5-40% by weight, and even more preferably 20-35% by weight.

[0054] The preferred embodiments described above are more conducive to improving the service life and stability of the catalyst.

[0055] In this invention, the content of metal-organic framework materials and binders in the catalyst is obtained by X-ray fluorescence spectroscopy analysis.

[0056] The present invention does not particularly limit the type of binder, as long as it can improve the stability of the catalyst. Those skilled in the art can select according to actual needs. Preferably, the binder is an aluminum-based binder, and more preferably, it is alumina.

[0057] In this invention, aluminum-based binders are preferred, as they are more conducive to the bonding of aluminum with ligands in metal-organic framework materials, extending the lifespan and activity of the catalyst, and improving the conversion rate of polyester and the yield of photocatalytic ammonia synthesis.

[0058] According to the present invention, preferably, the specific surface area of ​​the catalyst is 50 to 450 cm². 2 / g, more preferably 300-450cm 2 / g.

[0059] The specific surface area of ​​the catalyst described in this invention was obtained by nitrogen adsorption-desorption experiments. The methods for measuring specific surface area are well known to those skilled in the art, and will not be described in detail here.

[0060] The present invention does not particularly limit the particle size distribution of the catalyst, as long as it can meet the requirements of the catalytic reaction. Those skilled in the art can select according to actual needs. Preferably, the particle size distribution of the catalyst is 0.09-4 mm, more preferably 0.5-1 mm.

[0061] In this invention, the particle size distribution of the catalyst is obtained by sieving.

[0062] The present invention does not particularly limit the shape of the catalyst, as long as it can meet the requirements of the catalytic reaction. Those skilled in the art can select according to actual needs. Preferably, the shape of the catalyst is at least one of spherical, cylindrical, flake and strip, and more preferably spherical.

[0063] This invention does not impose any particular limitation on the preparation method of the catalyst, as long as the above-mentioned product can be obtained. According to a preferred embodiment of the invention, the preparation method of the catalyst includes the following steps:

[0064] The metal-organic framework material is mixed with a binder and / or a binder precursor, optionally shaped, and then calcined.

[0065] According to the present invention, preferably, the amount of metal-organic framework material and binder and / or binder precursor is such that the content of metal-organic framework material in the prepared catalyst is 55-98% by weight, more preferably 60-95% by weight, and even more preferably 65-80% by weight; and the content of binder is 2-45% by weight, more preferably 5-40% by weight, and even more preferably 20-35% by weight.

[0066] In this invention, the binder precursor refers to a substance that can be converted into the binder through a subsequent calcination step. Those skilled in the art, knowing the types of binders, know which binder precursor to choose.

[0067] The present invention does not particularly limit the types of binders and binder precursors, as long as they can improve the stability of the catalyst, and can be conventional choices in the art. Preferably, the binder and / or binder precursor is selected from at least one of alumina, boehmite, kaolinite, dickite, perlite, refractory stone and halloysite, more preferably alumina.

[0068] In this invention, the adhesive or adhesive precursor can be commercially available or prepared using methods known in the art.

[0069] In this invention, "optional" means that those skilled in the art can select the molding method of the catalyst according to actual needs. According to a preferred embodiment of the present invention, the molding method is ball forming.

[0070] The present invention does not particularly limit the specific implementation of the spheroid forming method, as long as the catalyst can be formed. Those skilled in the art can choose according to actual needs. Preferably, the present invention uses a method of placing the catalyst in a rotating device and spraying water while rolling to make the catalyst adhere and agglomerate into small balls.

[0071] The present invention does not have a particular limitation on the amount of water used, as long as it is sufficient to cause the catalyst to adhere and agglomerate into small balls. Those skilled in the art can select according to actual needs.

[0072] The present invention does not particularly limit the equipment for spherical forming, as long as it can form the catalyst. Those skilled in the art can select according to actual needs, such as at least one of a turntable, a sugar coating pan and a roller.

[0073] The present invention also includes sieving the catalyst after spheroidization.

[0074] In this invention, preferably, the method further includes drying after molding.

[0075] This invention does not impose any particular requirements on the mixing method, as long as it facilitates thorough mixing of the metal-organic framework material with the binder and / or binder precursor. Those skilled in the art can select the appropriate method based on actual needs. Preferably, the mixing conditions include: a mixing time of 0.5–48 h, more preferably 12–24 h; and a mixing temperature of 0–50 °C, more preferably 20–30 °C.

[0076] According to the present invention, preferably, the drying conditions include: a drying time of 0.5 to 48 hours, more preferably 12 to 24 hours; and a drying temperature of 50 to 150°C, more preferably 100 to 120°C.

[0077] According to the present invention, preferably, the calcination conditions include: a calcination temperature of 200–420°C, more preferably 250–350°C; and a calcination time of 2–12 h, more preferably 6–10 h.

[0078] This invention does not particularly limit the source of the metal-organic framework material; it can be prepared by any existing method or commercially available. This invention also does not particularly limit the preparation method of the metal-organic framework material, as long as the metal-organic framework material can be prepared; preferably, the method used to prepare the product with the above-described morphology is preferred.

[0079] According to one embodiment of the present invention, preferably, the method for preparing the metal-organic framework material includes:

[0080] (1) Mix alcohol compounds with organic solvents at a volume ratio of 1:8 to 100 to obtain a mixed solvent;

[0081] (2) The mixed solvent is mixed with the organic ligand and the metal precursor to obtain a precursor solution;

[0082] (3) Crystallize the precursor solution.

[0083] The inventors of this invention accidentally discovered during their research that mixing alcohol compounds with organic solvents in a specific volume ratio, and then adding organic ligands and metal precursors, could prepare metal-organic framework materials with specific morphologies.

[0084] In this invention, the organic solvent refers to various organic solvents conventionally used in the synthesis of metal-organic framework materials, excluding alcohols. Preferably, the organic solvent is selected from at least one of N,N-dimethylformamide, N,N-dimethylacetamide, and N,N-diethylacetamide, and more preferably N,N-dimethylformamide.

[0085] This invention allows for a wide range of selection of alcohol compounds. Preferably, the alcohol compounds are selected from C1-C5 alcohols. The alcohols can be monohydric or dihydric. According to a preferred embodiment of the invention, the alcohol compounds are selected from at least one of methanol, ethanol, ethylene glycol, and isopropanol, preferably methanol and / or ethylene glycol, and more preferably ethylene glycol. This preferred embodiment is more conducive to the competitive adsorption of alcohol compounds and organic ligands, thereby forming octahedral aggregates.

[0086] According to the present invention, preferably, the volume ratio of the alcohol compound to the organic solvent is 1:25 to 3:50. Using the volume ratio of the alcohol compound to the organic solvent within the above-preferred range is more conducive to preparing metal-organic framework materials with better catalytic performance.

[0087] Preferably, the mixing conditions in step (1) include: a mixing temperature of 10-80°C, more preferably 20-30°C, and even more preferably 25-30°C; and a mixing time of 10-120 min, more preferably 20-40 min, and even more preferably 15-25 min.

[0088] The present invention does not have any particular limitation on the specific mixing method of the mixed solvent, organic ligand and metal precursor in step (2), as long as the three are mixed evenly. In order to further improve the catalytic performance of the prepared material, preferably, step (2) includes: mixing the mixed solvent and organic ligand in a first mixing to obtain an organic ligand solution; and then mixing the organic ligand solution with the metal precursor in a second mixing to obtain the precursor solution.

[0089] The present invention allows for a wide range of choices regarding the amount of organic ligands and metal precursors to be added, and those skilled in the art can make adaptive choices based on specific needs to prepare metal-organic framework materials.

[0090] Preferably, the concentration of the organic ligand in the organic ligand solution is 3-15 g / L, more preferably 3.6-14.5 g / L, and most preferably 10.2-12.5 g / L.

[0091] Preferably, the concentration of the metal precursor in the precursor solution is 3-40 g / L, more preferably 3.3-38.9 g / L, and most preferably 20.5-25.5 g / L.

[0092] Preferably, the metal precursor is selected from at least one of anhydrous ferric chloride, ferric chloride hexahydrate, and ferric nitrate nonahydrate.

[0093] The first mixing in this invention only requires that the organic ligand dissolves in the mixed solvent. Preferably, the conditions for the first mixing include: a mixing temperature of 10–80°C, more preferably 20–30°C, and even more preferably 25–30°C; and a mixing time of 10–120 min, more preferably 20–40 min, and even more preferably 15–25 min.

[0094] In the method provided by this invention, the range of organic ligands selected is the same as that described in the first aspect above, and will not be repeated here.

[0095] The second mixing in this invention only requires that the metal precursor and the organic ligand solution be mixed uniformly. Preferably, the conditions for the second mixing include: a mixing temperature of 10–80°C, more preferably 20–30°C, and even more preferably 25–30°C; and a mixing time of 10–120 min, more preferably 50–100 min, and even more preferably 50–70 min.

[0096] The crystallization step (3) of this invention allows the metal precursor to react with the organic ligand to prepare a metal-organic framework material. The crystallization conditions are designed to produce the product with the aforementioned morphology. Preferably, the crystallization conditions include: a crystallization temperature of 120–180°C, more preferably 140–160°C, and even more preferably 145–155°C; and a crystallization time of 4–72 h, more preferably 10–48 h, and even more preferably 12–24 h.

[0097] According to a specific embodiment of the present invention, the method further includes a separation and drying step after crystallization in step (3), wherein the separation and drying can be carried out using conventional techniques in the art. Preferably, the separation is centrifugal separation, the centrifugation speed is preferably 4000-10000 r / min, more preferably 8000-12000 r / min; the centrifugation time is preferably 1-20 min, more preferably 5-10 min. The drying temperature is preferably 60-120℃, more preferably 90-110℃; the drying time is preferably 3-30 h, more preferably 20-24 h.

[0098] The photocatalytic degradation method provided by this invention has the advantage of high polyester conversion rate in polyester degradation.

[0099] The present invention will be described in detail below through embodiments. In the following embodiments, the characterization methods of XRD, SEM, and XPS are as described above and will not be repeated here.

[0100] In the following examples and comparative examples, the characterization methods for the content of metal-organic framework materials and binders in the catalyst, the specific surface area of ​​the catalyst, and the particle size distribution of the catalyst are as described above, and will not be repeated here.

[0101] In the following examples and comparative examples, the catalyst is spherical in shape.

[0102] Example 1

[0103] Catalyst preparation:

[0104] (1) Under stirring conditions, 2.5 mL of ethylene glycol and 42.5 mL of N,N-dimethylformamide were added to a glass and stirred at 25°C for 20 min.

[0105] (2) Add 0.498 g of terephthalic acid to the above mixed solvent and continue stirring at 25°C for 20 min.

[0106] (3) Add 0.973 g of anhydrous ferric chloride to the above solution and continue stirring at 25 °C for 60 min. Then transfer the stirred solution to a reaction vessel and heat at 150 °C for 24 h. Centrifuge the product at 10000 r / min for 8 min. Dry the obtained solid product at 100 °C for 24 h.

[0107] SEM images of the prepared metal-organic framework materials are shown below. Figure 1 XRD pattern can be found Figure 2 .from Figure 1As can be seen, the metal-organic framework material prepared in this embodiment has an octahedral aggregate morphology, and the octahedral aggregates are formed by the aggregation of microspheres. The morphological characteristics of the metal-organic framework material and the morphology of Fe obtained by SEM characterization are listed in Table 1. Figure 2 It can be seen that the metal-organic framework material prepared in this embodiment is MIL-101(Fe).

[0108] (4) The prepared metal-organic framework material was mixed evenly with alumina, wherein the content of metal-organic framework material was 70% by weight and the content of alumina was 30% by weight. Then, the mixture was rolled into balls, and the particle size distribution of the catalyst was 0.85-1.00 mm. The mixture was dried at 120°C for 12 h and finally calcined at 250°C for 12 h. The relevant parameters of the metal-organic framework material are shown in Table 1, and the other parameters of the catalyst are shown in Table 2.

[0109] Evaluation methods for photocatalytic degradation of polyester reactions:

[0110] The polyester conversion rate of the above-mentioned catalyst was determined using a temperature-controlled reactor. The reactor consists of a heating platform, reaction vessel, thermometer, pressure control valve, circulating water jacket, xenon lamp light source head, and xenon lamp light source power supply. The reaction vessel is made of stainless steel and has a sapphire crystal skylight at the top, which is 1 cm thick.

[0111] Add 2g of polyester (polyethylene terephthalate), 0.2g of the above catalyst, and 100g of water to the reactor; start stirring and increase the stirring speed to 300 rpm; then raise the system temperature to 25°C; and raise the system pressure to 1 MPa. Turn on the xenon lamp power source and aim the lamp head at the reactor window, with a xenon lamp density of 750 mW / cm³. 2 The light source used was a full-spectrum light with a wavelength of 200-800 nm. After reacting for 2 hours, the reaction solution was collected, filtered using Ф7 medium-speed qualitative filter paper, washed and filtered again with 50 g / L sodium hydroxide solution, and then washed and filtered again with deionized water. The filtered product was dried in an oven at 100℃ for 24 hours, and the mass of the solid product was finally weighed. The formula for calculating the polyester conversion rate is as follows:

[0112]

[0113] Where, m A m represents the total mass of the catalyst and polyester before the reaction. B This represents the total mass of the dried catalyst and polyester after the reaction. The reaction results are listed in Table 3 below.

[0114] Example 2

[0115] The catalyst was prepared according to the method of Example 1, except that the volume of ethylene glycol added in step (1) was 2 mL. The morphology of the metal-organic framework material and the morphology of Fe, as well as the parameters of other metal-organic framework materials, obtained by SEM characterization, are shown in Table 1, and the remaining parameters of the catalyst are shown in Table 2.

[0116] The photocatalytic degradation of polyester reaction evaluation method in Example 1 was followed, except that the reaction temperature was 300°C, the reaction pressure was 5 MPa, and the xenon lamp source density was 1200 mW / cm³. 2 The reaction results are listed in Table 3 below.

[0117] Example 3

[0118] The catalyst was prepared according to the method of Example 1, except that in step (1), ethylene glycol was replaced with an equal volume of methanol. The morphology of the metal-organic framework material and the morphology of Fe, as well as the parameters of other metal-organic framework materials, obtained by SEM characterization, are shown in Table 1, and the remaining parameters of the catalyst are shown in Table 2.

[0119] The photocatalytic degradation of polyester reaction evaluation method in Example 1 was followed, except that the reaction temperature was 200°C, the reaction pressure was 3 MPa, and the xenon lamp source density was 1500 mW / cm³. 2 The reaction results are listed in Table 3 below.

[0120] Example 4

[0121] Metal-organic framework materials were prepared according to the method of Example 1, except that the mass of terephthalic acid added in step (2) was 0.597 g. The morphological characteristics of the metal-organic framework materials obtained by SEM characterization, the morphology of Fe, and other parameters of the metal-organic framework materials are shown in Table 1, and the remaining parameters of the catalyst are shown in Table 2.

[0122] The photocatalytic degradation of polyester reaction evaluation method in Example 1 was followed, except that the reaction temperature was 10°C, the reaction pressure was 0.1 MPa, and the xenon lamp source density was 300 mW / cm³. 2 The reaction results are listed in Table 3 below.

[0123] Example 5

[0124] Metal-organic framework materials were prepared according to the method of Example 1, except that the solvothermal temperature (crystallization temperature) in step (3) was 130°C; and the content of metal-organic framework material in step (4) was 98% by weight and the content of alumina was 2% by weight. The morphological characteristics of the metal-organic framework material and the morphology of Fe obtained by SEM characterization and other parameters of the metal-organic framework material are shown in Table 1, and the remaining parameters of the catalyst are shown in Table 2.

[0125] The photocatalytic degradation of polyester reaction evaluation method in Example 1 was followed, except that the reaction temperature was 150°C, the reaction pressure was 5 MPa, and the xenon lamp source density was 1200 mW / cm³. 2 The reaction results are listed in Table 3 below.

[0126] Example 6

[0127] Metal-organic framework materials were prepared according to the method of Example 1, except that in step (2), terephthalic acid was replaced with 0.543 g of 2-amino-terephthalic acid. The morphological characteristics of the metal-organic framework materials obtained by SEM characterization, the morphology of Fe, and other parameters of the metal-organic framework materials are shown in Table 1, and the remaining parameters of the catalyst are shown in Table 2.

[0128] The photocatalytic degradation of polyester reaction was evaluated according to the evaluation method of Example 1. The reaction results are listed in Table 3 below.

[0129] Example 7

[0130] The method of Example 1 was followed, except that in step (1), the amount of N,N-dimethylformamide used was 37.5 mL. The morphological characteristics of the metal-organic framework material and the morphology of Fe, as well as other parameters of the metal-organic framework material, obtained by SEM characterization, are shown in Table 1, and the remaining parameters of the catalyst are shown in Table 2.

[0131] The photocatalytic degradation of polyester reaction was evaluated according to the evaluation method of Example 1. The reaction results are listed in Table 3 below.

[0132] Example 8

[0133] The method is the same as in Example 1, except that the amount of terephthalic acid added in step (2) is 0.675 g, and the amount of anhydrous ferric chloride added in step (3) is 1.8 g. The morphological characteristics of the metal-organic framework material and the morphology of Fe obtained by SEM characterization, as well as the parameters of other metal-organic framework materials, are shown in Table 1, and the remaining parameters of the catalyst are shown in Table 2.

[0134] The photocatalytic degradation of polyester reaction was evaluated according to the evaluation method of Example 1. The reaction results are listed in Table 3 below.

[0135] Example 9

[0136] The method is the same as in Example 1, except that in step (4), the content of the metal-organic framework is 95% by weight and the content of alumina is 5% by weight. The remaining parameters of the catalyst are shown in Table 2.

[0137] The photocatalytic degradation of polyester reaction was evaluated according to the evaluation method of Example 1. The reaction results are listed in Table 3 below.

[0138] Example 10

[0139] The method is the same as in Example 1, except that in step (4), the content of the metal-organic framework is 55% by weight and the content of alumina is 45% by weight. The remaining parameters of the catalyst are shown in Table 2.

[0140] The photocatalytic degradation of polyester reaction was evaluated according to the evaluation method of Example 1. The reaction results are listed in Table 3 below.

[0141] Example 11

[0142] The method is the same as in Example 1, except that in step (4), alumina is replaced with an equal amount of boehmite (calculated as alumina). The remaining parameters of the catalyst are shown in Table 2.

[0143] The photocatalytic degradation of polyester reaction was evaluated according to the evaluation method of Example 1. The reaction results are listed in Table 3 below.

[0144] Example 12

[0145] The catalyst was prepared according to the method of Example 1, except that the catalyst particle size distribution in step (4) was 3.35-4.00 mm. The remaining parameters of the catalyst are shown in Table 2.

[0146] The photocatalytic degradation of polyester reaction was evaluated according to the evaluation method of Example 1. The reaction results are listed in Table 3 below.

[0147] Example 13

[0148] The catalyst was prepared according to the method of Example 1, except that ethylene glycol was not added in step (1) and zirconium chloride was added in step (3). The metal-organic framework material prepared was UiO-66. The morphology of the metal-organic framework material obtained by SEM characterization was octahedral, with a smooth surface and no microsphere structure. The parameters of other metal-organic framework materials are shown in Table 1, and the remaining parameters of the catalyst are shown in Table 2.

[0149] The photocatalytic degradation of polyester reaction evaluation method in Example 1 was followed, except that the reaction temperature was 300°C, the reaction pressure was 5 MPa, and the xenon lamp source density was 1200 mW / cm³. 2 The reaction results are listed in Table 3 below.

[0150] Example 14

[0151] The catalyst was prepared according to the method of Example 1, except that the solvothermal temperature in step (3) was 110°C. The metal-organic framework material prepared was MIL-101. The morphology of the metal-organic framework material obtained by SEM characterization was octahedral, with a smooth surface and no microsphere structure. The morphology of Fe and other parameters of the metal-organic framework material are shown in Table 1. The remaining parameters of the catalyst are shown in Table 2.

[0152] The photocatalytic degradation of polyester reaction evaluation method in Example 1 was followed, except that the reaction temperature was 300°C, the reaction pressure was 5 MPa, and the xenon lamp source density was 1200 mW / cm³. 2 The reaction results are listed in Table 3 below.

[0153] Example 15

[0154] The method of Example 1 was followed, except that ethylene glycol was not added in step (1). The metal-organic framework material prepared in this way was MIL-101(Fe). The morphology of the metal-organic framework material obtained by SEM characterization was octahedral, with a smooth surface and no microsphere structure. The morphology of Fe and the parameters of other metal-organic framework materials are shown in Table 1, and the remaining parameters of the catalyst are shown in Table 2.

[0155] The photocatalytic degradation of polyester reaction evaluation method in Example 1 was followed, except that the reaction temperature was 300°C, the reaction pressure was 5 MPa, and the xenon lamp source density was 1200 mW / cm³. 2 The reaction results are listed in Table 3 below.

[0156] Example 16

[0157] The catalyst was prepared according to the method of Example 1, except that in step (1), ethylene glycol was replaced with an equal amount of acetic acid. The metal-organic framework material prepared was MIL-101(Fe). The morphological characteristics of the metal-organic framework material and the morphology of Fe, as well as the parameters of other metal-organic framework materials, obtained by SEM characterization, are shown in Table 1, and the remaining parameters of the catalyst are shown in Table 2.

[0158] The photocatalytic degradation of polyester reaction evaluation method in Example 1 was followed, except that the reaction temperature was 300°C, the reaction pressure was 5 MPa, and the xenon lamp source density was 1200 mW / cm³. 2 The reaction results are listed in Table 3 below.

[0159] Comparative Example 1

[0160] The catalyst was prepared according to the method of Example 16.

[0161] The evaluation method for the degradation of polyester reaction according to Example 16 was followed, except that a light source was not used. The reaction results are listed in Table 3 below.

[0162] Example 17

[0163] The catalyst was prepared according to the method in Example 1.

[0164] The photocatalytic degradation of polyester reaction evaluation method in Example 1 was followed, except that polyethylene terephthalate was replaced with an equal amount of polybutylene terephthalate, and water was replaced with an equal amount of oxalic acid. The reaction results are listed in Table 3 below.

[0165] Example 18

[0166] The catalyst was prepared according to the method in Example 1.

[0167] The photocatalytic degradation of polyester reaction was evaluated according to the method in Example 1, except that the amount of polyethylene terephthalate used was 2.4 g and the amount of catalyst used was 0.2 g. The reaction results are listed in Table 3 below.

[0168] Comparative Example 2

[0169] The catalyst was prepared according to the method of Example 1, except that ethylene glycol was not added in step (1), and N,N-dimethylformamide was replaced with an equal amount of water, and terephthalic acid was not added in step (2). The material obtained by this method was Fe2O3. The morphological characteristics of the material and the morphology of Fe, as well as the parameters of other materials, obtained by SEM characterization are shown in Table 1, and the remaining parameters of the catalyst are shown in Table 2.

[0170] The photocatalytic degradation of polyester reaction was evaluated according to the evaluation method of Example 1. The reaction results are listed in Table 3 below.

[0171] Table 1

[0172]

[0173]

[0174] Note: Fe in Table 1 of this invention II Fe III A value of 0 indicates that the catalyst contains only Fe. III In Table 1 of this invention, " / " indicates that the catalyst does not contain this feature.

[0175] Table 2

[0176]

[0177]

[0178] Table 3

[0179]

[0180]

[0181] The results in the table above show that, compared with the comparative example, the photocatalytic degradation method for polyester provided by this invention can improve the conversion rate of polyester degradation. This is likely because metal-organic framework materials possess excellent photocatalytic performance and tunable structural characteristics, which can effectively promote the decomposition of polyester molecules and solve the problem of low conversion rate in photocatalytic polyester degradation.

[0182] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A method for photocatalytic degradation of polyester, characterized in that, The method includes the following steps: In the presence of a solvent, polyester is subjected to a photocatalytic degradation reaction with a catalyst; The catalyst includes a metal-organic framework material and optionally a binder.

2. The method according to claim 1, wherein, The mass ratio of catalyst to polyester is 1:5-100; Preferably, the polyester is selected from at least one of polyethylene terephthalate, polybutylene terephthalate, and polyarylate, and is preferably polyethylene terephthalate; And / or, the solvent is selected from at least one of water, alcohols and organic acids, preferably at least one of water, methanol, ethanol, ethylene glycol, oxalic acid and isopropanol; And / or, the conditions for the photocatalytic degradation reaction include: an operating temperature of 10–300°C, preferably 25–300°C; an operating pressure of 0.1–10 MPa, preferably 1–5 MPa; and a light source density of 100–1500 mW / cm³. 2 The wavelength of the light source is 200-800nm.

3. The method according to claim 1 or 2, wherein, The metal in the metal-organic framework material is selected from at least one of Fe, Zr, Hf, Al, Sr and Cr, more preferably Fe; Preferably, the metal-organic framework material is at least one of MIL-101 (Fe), MIL-53 (Fe), and MIL-88 (Fe); And / or, Fe is present in the metal-organic framework material. II and Fe III Two forms, of which Fe II Fe III The ratio is 1:100 to 100:1, preferably 1:4 to 4:1, and more preferably 1:2 to 2:1; And / or, the organic ligand in the metal-organic framework material is selected from terephthalic acid and its derivatives, preferably at least one of terephthalic acid, 2-aminoterephthalic acid, 2,4-diaminoterephthalic acid, 2-hydroxyterephthalic acid, 2,4-dihydroxyterephthalic acid, 2-carboxyterephthalic acid and 2,4-dicarboxyterephthalic acid, and more preferably at least one of terephthalic acid, 2-aminoterephthalic acid and 2,4-diaminoterephthalic acid.

4. The method according to any one of claims 1-3, wherein, The metal-organic framework material has an octahedral aggregate morphology; Preferably, the edge length of the regular octahedral aggregate is 0.5–2 μm, more preferably 1–1.5 μm, and even more preferably 1–1.2 μm; And / or, the octahedral aggregates are obtained by the aggregation of microspheres; Preferably, the diameter of the microspheres is 20–100 nm, more preferably 40–80 nm, and even more preferably 50–60 nm; And / or, the specific surface area of ​​the metal-organic framework material is 50–500 cm². 2 / g, preferably 300-500cm 2 / g.

5. The method according to any one of claims 1-4, wherein, Based on the total amount of the catalyst, the content of the metal-organic framework material is 55-98% by weight, preferably 60-95% by weight, more preferably 65-80% by weight; the content of the binder is 2-45% by weight, preferably 5-40% by weight, more preferably 20-35% by weight. Preferably, the adhesive is an aluminum-based adhesive, and more preferably aluminum oxide; And / or, the specific surface area of ​​the catalyst is 50–450 cm². 2 / g, preferably 300-450cm 2 / g; And / or, the particle size distribution of the catalyst is 0.09–4 mm, preferably 0.5–1 mm; Preferably, the catalyst is at least one of spherical, cylindrical, flake, and strip shapes, with spherical being the most preferred.

6. The method according to any one of claims 1-5, wherein, The method for preparing the catalyst includes the following steps: The metal-organic framework material is mixed with a binder and / or a binder precursor, optionally shaped, and then calcined.

7. The method according to claim 6, wherein, The amount of metal-organic framework material and binder and / or binder precursor in the prepared catalyst is such that the content of metal-organic framework material in the prepared catalyst is 55-98% by weight, preferably 60-95% by weight, more preferably 65-80% by weight; and the content of binder is 2-45% by weight, preferably 5-40% by weight, more preferably 20-35% by weight. And / or, the binder and / or binder precursor is selected from at least one of alumina, boehmite, kaolinite, dickite, perlite, refractory stone and halloysite, preferably alumina.

8. The method according to claim 6 or 7, wherein, The method also includes drying after molding; And / or, the forming method is ball forming; And / or, the mixing conditions include: a mixing time of 0.5 to 48 hours; and a mixing temperature of 0 to 50°C. And / or, the drying conditions include: a drying time of 0.5 to 48 hours; and a drying temperature of 50 to 150°C. And / or, the calcination conditions include: a calcination temperature of 200–420°C, preferably 250–350°C; and a calcination time of 2–12 h, preferably 6–10 h.

9. The method according to any one of claims 1-8, wherein, The preparation method of the metal-organic framework material includes: (1) Mix alcohol compounds with organic solvents at a volume ratio of 1:8 to 100 to obtain a mixed solvent; (2) The mixed solvent is mixed with the organic ligand and the metal precursor to obtain a precursor solution; (3) Crystallize the precursor solution.

10. The method according to claim 9, wherein, The alcohol compound is selected from C1-C5 alcohols, preferably selected from at least one of methanol, ethanol, ethylene glycol and isopropanol, more preferably methanol and / or ethylene glycol, and most preferably ethylene glycol; And / or, the organic solvent is selected from at least one of N,N-dimethylformamide, N,N-dimethylacetamide and N,N-diethylacetamide, preferably N,N-dimethylformamide; Preferably, the volume ratio of the alcohol compound to the organic solvent is 1:25 to 3:50; Preferably, the mixing conditions in step (1) include: a mixing temperature of 10-80°C, preferably 20-30°C, more preferably 25-30°C; and a mixing time of 10-120 min, preferably 20-40 min, more preferably 15-25 min. And / or, the crystallization conditions include: a crystallization temperature of 120–180°C and a crystallization time of 4–72 h.

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