A perovskite / CTF composite photocatalyst, its preparation method and application

Abstract

This invention belongs to the field of catalytic degradation technology, specifically relating to the pyrolysis of lignin model compounds, and more specifically to a perovskite / CTF composite photocatalyst, its preparation method, and its application. The method involves simultaneously combining and synthesizing CTF with cesium, bismuth, and bromine sources using a molten salt method to form a Cs3Bi2Br9 / CTF composite. The molten salt method is performed at a temperature of 170–370°C, and the mass ratio of CTF to cesium source is 1–10:1. This invention, through the composite of perovskite and CTF, not only achieves photocatalytic pyrolysis of lignin but also allows for fine-tuning of the photocatalyst's electronic structure, resulting in a suitable electronic structure and improved efficiency during the photocatalytic process. + and . O2 ‑ The generation of these compounds increases the yield of aromatic monomers prepared from lignin through pyrolysis.

Description

Technical Field

[0001] This invention belongs to the field of catalytic degradation technology, and relates to the pyrolysis of lignin model compounds, specifically to a perovskite / CTF (triazine framework material) composite photocatalyst and its preparation method and application. Background Technology

[0002] The information disclosed in this background section is intended only to enhance understanding of the overall background of the invention and is not necessarily to be construed as an admission or in any way implying that such information constitutes prior art known to those skilled in the art.

[0003] Oxygen-containing compounds such as phenols, alcohols, acids, ethers, and aldehydes are important source materials in modern chemical engineering. Traditional methods of extracting oxygen-containing compounds from petrochemical resources not only emit carbon dioxide during production but also involve multiple hazardous processes.

[0004] Lignin is a three-dimensional network polymer formed by the random polymerization of syringylpropane units (S-type), guaiacolylpropane units (G-type), and p-hydroxyphenylpropane units (H-type). These three aromatic unit derivatives are linked by C-C bonds (β-O-4, α-O-4, β-1, β-5, and 5-5) and CO bonds. The key to the high-value utilization of lignin is how to selectively break these bonds to obtain monophenolic compounds corresponding to the three structural units. CO bonds, due to their low bond energy and high abundance, have attracted much attention; however, according to the inventors' research, the complex linkage structure of lignin results in a maximum yield of only 27% of aromatic monomers obtained by breaking CO bonds. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide a perovskite / CTF composite photocatalyst, its preparation method, and its applications. This invention, through the composite of perovskite and CTF, not only achieves photocatalytic cleavage of lignin but also enables fine-tuning of the photocatalyst's electronic structure, giving it a suitable electronic structure and improving the efficiency of photocatalysis. + and . O2 - The generation of these compounds increases the yield of aromatic monomers prepared from lignin through pyrolysis.

[0006] To achieve the above objectives, the technical solution of the present invention is as follows:

[0007] On the one hand, a method for preparing a perovskite / CTF composite photocatalyst involves simultaneously combining and synthesizing CTF with a cesium source, a bismuth source, and a bromine source using a molten salt method to form a composite of Cs3Bi2Br9 and CTF; wherein the temperature of the molten salt method is 170–370℃, and the mass ratio of CTF to cesium source is 1–10:1.

[0008] To further improve the yield of aromatic monomers from lignin cleavage, this invention focuses on the cleavage direction of the C-C bonds in lignin. Photocatalysis can utilize photogenerated electrons and the cooperation of active free radicals to achieve the cleavage of C-C bonds in a low-energy state, thereby avoiding the re-condensation of aldehydes and phenols and increasing the yield of aromatic monomers. Regarding C... α -C β Bond cleavage, photocatalyst cleavage of C α -C β The C bond is activated by holes generated by the photocatalyst. β Starting with the -H bond, C is formed. β • Free radical intermediate, then C β The free radical intermediate reacts successively with O2 and H· produced by proton reduction to form a metastable peroxide intermediate. Finally, the metastable peroxide intermediate undergoes electron rearrangement, thereby breaking the C2O chain. α -C β The reaction pathway requires the sequential participation of oxygen and H· radicals, but the presence of oxygen consumes electrons and H· radicals, thus significantly limiting the reaction efficiency. Photocatalytic cracking of C α -C β In addition to the bonds, the oxidizing power of the photocatalyst is also required to a certain extent. Because of its extremely strong oxidizing power, ·OH can indiscriminately attack the bonds in lignin, which is actually detrimental to C. β • Formation of free radical intermediates. Therefore, h + and . O2 - Due to its suitable oxidizing power, at C β • It plays an important role in the formation of free radicals and peroxide intermediates. Therefore, in order for photocatalysts to photodegrade C… α -C β To achieve the desired bond, the photocatalyst must possess a suitable electronic structure to produce h. + and . O2 - Simultaneously, the conduction band position of the photocatalyst must be below 0.33V, and the valence band position must be below 1.99V. To achieve the controllable production of free radicals, it is necessary to select a suitable substrate photocatalyst and fine-tune the electronic structure of the substrate photocatalyst.

[0009] The valence band of perovskite is 1.83V, satisfying the requirements for the valence band. Furthermore, perovskite's electronic structure can be altered by changes in external stress, satisfying the requirement for carbon fragmentation. α -C βThe need for tunable bond electronic structure. This invention embeds perovskite quantum dots into a CTF framework, which not only protects the perovskite and improves its stability, but also introduces metal sites into the CTF to enhance its catalytic activity. Furthermore, perovskite and CTF can form a heterojunction, accelerating the separation of photogenerated electrons and holes.

[0010] Currently, there are various methods to embed perovskite into CTF, such as using silica gel as a hard template to load perovskite quantum dots onto the porous CTF surface. However, this process is complex, the perovskite loading rate is low, and it is difficult to achieve controllable adjustment of the electronic structure of the perovskite-CTF composite material. This invention utilizes the molten salt method to embed Cs3Bi2Br9 into CTF during the synthesis process, which can load more perovskite into the CTF. By adjusting the temperature of the molten salt method, the electronic structure of the composite material can be controllably adjusted, thereby improving the yield of photocatalytic degradation of lignin to prepare aromatic monomers.

[0011] On the other hand, a perovskite / CTF composite photocatalyst is obtained by the above preparation method.

[0012] Thirdly, the application of a perovskite / CTF composite photocatalyst in the photocatalytic degradation of lignin.

[0013] Fourthly, a method for photocatalytic degradation of lignin to prepare aromatic monomers involves adding the above-mentioned perovskite / CTF composite photocatalyst to a solution containing lignin and subjecting it to light treatment.

[0014] The beneficial effects of this invention are as follows:

[0015] (1) This invention uses CTF to combine with perovskite. By utilizing the inherent pores inside CTF, perovskite quantum dots are grown in a confined space, which effectively protects the perovskite quantum dots, solves the problem of instability of perovskite quantum dots, and introduces metal active sites into CTF, which effectively improves photocatalytic performance.

[0016] (2) This invention employs a molten salt method to prepare perovskite / CTF composite photocatalysts in one step, which not only improves the loading efficiency of perovskite on CTF, but also enables fine-tuning of the electronic structure of the photocatalyst by adjusting the temperature, thereby achieving photo-cracking of C. α -C β In addition, the molten salt method used in this invention has advantages such as simple preparation method, short preparation cycle, and low equipment requirements.

[0017] (3) Experiments have shown that the perovskite / CTF composite photocatalyst prepared in this invention can cleave lignin model compounds under visible light or natural light, with a cleavage conversion rate of up to 100%, a benzaldehyde yield of up to 64%, and a phenyl formate yield of up to 70%. It is green, clean and safe. Attached Figure Description

[0018] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0019] Figure 1 These are transmission electron microscope (TEM) images of the composite photocatalytic materials in the embodiments of the present invention; wherein, (a) is a low-magnification TEM image of CTF, (b) is a high-magnification TEM image of CTF, (c) is a low-magnification TEM image of CBB, (d) is a high-magnification TEM image of CBB, (e) is a transmission electron microscope (TEM) image of CC-270, and (f) is a high-magnification TEM image of CC-270.

[0020] Figure 2 These are atomic force microscopy spectra of the composite photocatalytic materials in the embodiments of the present invention; (a) is CTF, and (b) is CC-270.

[0021] Figure 3 This is the EDS spectrum of CC-270 prepared according to an embodiment of the present invention.

[0022] Figure 4 The image shows the XRD pattern of the composite photocatalytic material in this embodiment of the invention.

[0023] Figure 5 The image shows the infrared spectrum of the composite photocatalytic material in this embodiment of the invention.

[0024] Figure 6 The image shows the total X-ray photoelectron spectroscopy (XPS) spectrum of the composite photocatalytic material in this embodiment of the invention.

[0025] Figure 7 The image shows the UV-drs spectrum of the composite photocatalytic material in this embodiment of the invention.

[0026] Figure 8 The MS curves of the composite photocatalytic material in this embodiment of the invention are shown.

[0027] Figure 9 This is an electronic structure diagram of the composite photocatalytic material in an embodiment of the present invention.

[0028] Figure 10 This is a photocatalytic cracking curve of the composite photocatalytic material on the lignin model compound in an embodiment of the present invention. Detailed Implementation

[0029] It should be noted that the following detailed descriptions are exemplary and intended to provide further illustration of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0030] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0031] Given the low yield of existing lignin pyrolysis for the preparation of aromatic monomers, this invention proposes a perovskite / CTF composite photocatalyst, its preparation method, and its application.

[0032] A typical embodiment of the present invention provides a method for preparing a perovskite / CTF composite photocatalyst, wherein CTF is simultaneously composited and synthesized with a cesium source, a bismuth source and a bromine source using a molten salt method to form a composite of Cs3Bi2Br9 and CTF; wherein the temperature of the molten salt method is 170 to 370°C and the mass ratio of CTF to cesium source is 1 to 10:1.

[0033] The cesium source is a cesium-containing substance, such as cesium nitrate or cesium bromide. In some embodiments, the cesium source is cesium bromide. Using cesium bromide can serve as both a cesium source and a bromine source, reducing the types of chemical reagents required, lowering costs, avoiding the introduction of impurities, and improving the perovskite formation efficiency.

[0034] The bismuth source is a bismuth-containing substance, such as bismuth nitrate or bismuth tribromide. In some embodiments, the bismuth source is bismuth tribromide. Using bismuth tribromide can serve as both a bismuth source and a bromine source, reducing the types of chemical reagents required, lowering costs, avoiding the introduction of impurities, and improving the perovskite production efficiency.

[0035] The bromine source is a substance containing bromine, such as ammonium bromide, bismuth tribromide, cesium bromide, etc. In some embodiments, the bromine source is bismuth tribromide and cesium bromide.

[0036] In some embodiments, the cesium source, bismuth source, and bromine source are CsBr and BiBr3, with a molar ratio of CsBr to BiBr3 of 1:0.5 to 1.5. This is more conducive to saving raw materials.

[0037] In the molten salt method, molten salt is used as a dispersion medium after being heated and melted, allowing the various materials to recombine and react within the molten salt. In some embodiments, the CTF, cesium source, bismuth source, bromine source, and molten salt are ground uniformly, then heated to 170–370°C to melt the molten salt, simultaneously carrying out recombination and synthesis. Uniform grinding facilitates better contact between the materials, further improving the formation efficiency of Cs3Bi2Br9 and the loading efficiency of Cs3Bi2Br9 in the CTF. It also promotes the uniform distribution of Cs3Bi2Br9 within the CTF, thereby further enhancing catalytic stability. After recombination and synthesis, the materials are washed and dried to remove the molten salt.

[0038] In some embodiments, the temperature for the molten salt process is 170–320°C, preferably 220–320°C, and more preferably 250–290°C. Studies have shown that the yield of aromatic monomers increases sequentially under these conditions.

[0039] In some embodiments, the reaction time using the molten salt method is 1 to 5 hours.

[0040] In some embodiments, the molten salt used in the molten salt method is one or more of KNO3, NaNO3, and KBr.

[0041] In one or more embodiments, the molten salt used in the molten salt method is a mixture of KNO3, NaNO3, and KBr. Specifically, the molar ratio of KNO3, NaNO3, and KBr is 1:0.4–0.6:0.4–0.6. Under this ratio, it is more conducive to the melting of the molten salt in the temperature range of 170–370°C, and to the full contact and reaction of the various materials.

[0042] Another embodiment of the present invention provides a perovskite / CTF composite photocatalyst, obtained by the above preparation method.

[0043] A third embodiment of the present invention provides the application of a perovskite / CTF composite photocatalyst in the photocatalytic degradation of lignin or its analogues.

[0044] The fourth embodiment of the present invention provides a method for preparing aromatic monomers by photocatalytic degradation of lignin or its analogues, wherein the above-mentioned perovskite / CTF composite photocatalyst is added to a solution containing lignin or its analogues and subjected to phototreatment.

[0045] In some embodiments, the concentration of the perovskite / CTF composite photocatalyst is 2.0–3.0 g / L.

[0046] In some embodiments, the solution containing lignin or its analogues contains a lignin model compound. Specifically, the lignin model compound is 2-phenoxy-1-phenylethanol (pp-ol).

[0047] To enable those skilled in the art to better understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below with reference to specific embodiments and comparative examples.

[0048] The CTF preparation process in the following examples was carried out in accordance with the reference (ZALan, M.Wu, ZPFang, et al. Ionothermal synthesis of covalent triazine frameworks in a NaCl-KCl-ZnCl2eutectic salt for the hydrogen evolution reaction. Angew. Chem. Int. Ed, 2022, 61, 202201482).

[0049] Example 1

[0050] A method for preparing a perovskite (Cs3Bi2Br9) / CTF composite photocatalyst includes the following steps:

[0051] CTF (1.0 g), CsBr (0.128 g), BiBr3 (0.269 g), KNO3 (0.101 g), NaNO3 (0.0425 g), and KBr (0.0595 g) were mixed and ground for 15 minutes. The mixture was then placed in a muffle furnace and calcined at 170 °C for 1 hour. The resulting powder was allowed to cool naturally to room temperature and washed three times with ethanol and DMSO, respectively. Each wash was performed by sonication for 10 minutes followed by centrifugation at 10,000 rpm for 10 minutes, and the solid precipitate was collected. The resulting product was dried under vacuum at 40 °C for 12 hours to obtain the Cs3Bi2Br9 / CTF composite photocatalyst, designated CC-170.

[0052] Example 2

[0053] A method for preparing a perovskite (Cs3Bi2Br9) / CTF composite photocatalyst includes the following steps:

[0054] CTF (1.0 g), CsBr (0.128 g), BiBr3 (0.269 g), KNO3 (0.101 g), NaNO3 (0.0425 g), and KBr (0.0595 g) were mixed and ground for 15 minutes. The mixture was then placed in a muffle furnace and calcined at 220 °C for 1 hour. The resulting powder was allowed to cool naturally to room temperature and washed three times with ethanol and DMSO, respectively. Each wash was performed by sonication for 10 minutes followed by centrifugation at 10,000 rpm for 10 minutes, and the solid precipitate was collected. The resulting product was dried under vacuum at 40 °C for 12 hours to obtain the Cs3Bi2Br9 / CTF composite photocatalyst, designated CC-220.

[0055] Example 3

[0056] A method for preparing a perovskite (Cs3Bi2Br9) / CTF composite photocatalyst includes the following steps:

[0057] CTF (1.0 g), CsBr (0.128 g), BiBr3 (0.269 g), KNO3 (0.101 g), NaNO3 (0.0425 g), and KBr (0.0595 g) were mixed and ground for 15 minutes. The mixture was then placed in a muffle furnace and calcined at 270 °C for 1 hour. The resulting powder was allowed to cool naturally to room temperature and washed three times with ethanol and DMSO, respectively. Each wash was performed by sonication for 10 minutes followed by centrifugation at 10,000 rpm for 10 minutes, and the solid precipitate was collected. The resulting product was dried under vacuum at 40 °C for 12 hours to obtain the Cs3Bi2Br9 / CTF composite photocatalyst, designated CC-270.

[0058] Example 4

[0059] A method for preparing a perovskite (Cs3Bi2Br9) / CTF composite photocatalyst includes the following steps:

[0060] CTF (1.0 g), CsBr (0.128 g), BiBr3 (0.269 g), KNO3 (0.101 g), NaNO3 (0.0425 g), and KBr (0.0595 g) were mixed and ground for 15 minutes. The mixture was then placed in a muffle furnace and calcined at 320 °C for 1 hour. The resulting powder was allowed to cool naturally to room temperature and washed three times with ethanol and DMSO, respectively. Each wash was performed by sonication for 10 minutes followed by centrifugation at 10,000 rpm for 10 minutes, and the solid precipitate was collected. The resulting product was dried under vacuum at 40 °C for 12 hours to obtain the Cs3Bi2Br9 / CTF composite photocatalyst, designated CC-320.

[0061] Example 5

[0062] A method for preparing a perovskite (Cs3Bi2Br9) / CTF composite photocatalyst includes the following steps:

[0063] CTF (1.0 g), CsBr (0.128 g), BiBr3 (0.269 g), KNO3 (0.101 g), NaNO3 (0.0425 g), and KBr (0.0595 g) were mixed and ground for 15 minutes. The mixture was then placed in a muffle furnace and calcined at 370 °C for 1 hour. The resulting powder was allowed to cool naturally to room temperature and washed three times with ethanol and DMSO, respectively. Each wash was performed by sonication for 10 minutes followed by centrifugation at 10,000 rpm for 10 minutes, and the solid precipitate was collected. The resulting product was dried under vacuum at 40 °C for 12 hours to obtain the Cs3Bi2Br9 / CTF composite photocatalyst, designated CC-370.

[0064] Comparative Example 1

[0065] A method for preparing a perovskite (Cs3Bi2Br9) photocatalyst includes the following steps:

[0066] CsBr (0.128 g), BiBr3 (0.269 g), KNO3 (0.101 g), NaNO3 (0.0425 g), and KBr (0.0595 g) were mixed and ground for 15 minutes. The mixture was then placed in a muffle furnace and calcined at 200 °C for 24 hours. The resulting powder was allowed to cool naturally to room temperature and washed three times with ethanol and DMSO, respectively. Each wash was performed by sonication for 10 minutes followed by centrifugation at 10,000 rpm for 10 minutes, and the solid precipitate was collected. The resulting product was dried under vacuum at 40 °C for 12 hours to obtain the Cs3Bi2Br9 / CTF composite photocatalyst, denoted as CBB.

[0067] Product characterization of composite photocatalytic materials:

[0068] Figure 1 The images shown are transmission electron microscope (TEM) and high-magnification TEM images of CTF, CBB, and CC-270. Figure 1 (a) and (b) show the transmission electron microscope images of CTF, which show that CTF is a 3D stacked structure. Figure 1 (c) and (d) show that the CBB is a two-dimensional layered structure with lattice stripe widths of 0.25 nm and 0.15 nm, respectively, corresponding to the (005) and (202) crystal planes of the CBB. Figure 1 (e) and (f) show the transmission electron microscope and high-power transmission electron microscope of CC-270. It can be seen from the figure that CC-270 has a layered structure and CBB is distributed on the surface of CTF in the form of quantum dots. Figure 2(a) and (b) are the AFM images of CTF and CC-270, respectively. As can be seen from the images, the CTF surface is relatively smooth, which is consistent with the TEM results. After loading CBB quantum dots, the surface becomes rough, and irregular spherical particles are clearly visible, indicating that the CBB quantum dots are semi-embedded on the CTF surface.

[0069] Figure 3 The image shows the EDS spectrum of CC-270. As can be seen from the image, C, N, Cs, Bi, and Br are all present, indicating that the binding of CBB and CTF is successful.

[0070] Figure 4 The XRD patterns of CBB, CTF, and CC-X (X = 170, 220, 270, 320, and 370) are shown. The characteristic peaks at 10.8°, 25.3°, 31.6°, 46.4°, and 57.3° correspond to the (001), (200), (202), (005), and (402) crystal planes of Cs3Bi2Br9 (JCPDS No. 44-0714), respectively. For CTF, the peaks at 7.6°, 14.6°, and 26.8° correspond to the (1010), (1120), and (0002) crystal planes, respectively. The peak at 7.8° corresponds to the in-plane reflection peak of CTF. The peak at 26.8° corresponds to interlayer reflection. The characteristic peaks of Cs3Bi2Br9 and CTF can be found in the CC-X (X = 170, 220, 270, 320, and 370) peaks, indicating that the combination of CBB and CTF is successful. Furthermore, after the combination of CBB and CTF, the peak height at 31.6° continuously increases, while the peak intensity at 10.8° continuously decreases, indicating that the dominant crystal plane of CBB changes from (001) to (202). With increasing calcination temperature, the peak at (202) migrates to a larger angle, indicating a decrease in interlayer spacing. This is because as the calcination temperature increases, the triazine framework expands and compresses the CBB, leading to a decrease in lattice spacing.

[0071] Figure 5 The image shows the infrared spectra of CTF, CBB, and CC-X (X = 170, 220, 270, 320, and 370). For CTF, 3356 and 3186 cm⁻¹ are also shown. -1 The peak at 3065 cm⁻¹ corresponds to the stretching vibration peak of NH. -1 The peak at 2234 cm⁻¹ corresponds to the stretching vibration peak of CH. -1 The peak at that point corresponds to the oligomer residues from the CTF synthesis process, at 1366-1663 cm⁻¹. -1 The series of peaks correspond to the stretching vibration peaks of CN in the benzene ring and the triazine ring.

[0072] 1019cm -1The peak at 550 cm⁻¹ corresponds to the characteristic CO peaks at 820 and 550 cm� -1 The peaks correspond to the bending vibration peaks of CH and NH in the triazine ring, respectively. For CBB, 3434 cm⁻¹ -1 The peak corresponds to C S -H. 519cm -1 The peaks correspond to the characteristic peaks of Bi-Br. In summary, the infrared characteristic peaks of CC-X (X = 170, 220, 270, 320, and 370) encompass the characteristic peaks of CTF and CBB, indicating that the combination of CTF and CBB is successful.

[0073] Figure 6 The image shows the XPS spectrum of CC-270. As can be seen from the image, CC-270 contains all the elements of CTF (C and N) and CBB (Cs, Bi, and Br), indicating that the combination of CTF and CBB is successful.

[0074] Figure 7 The UV-drs spectra of CBB, CTF, and CC-X (X = 170, 220, 270, 320, and 370) are shown. Calculations based on the Kubelka-Munk equations yield band gaps of 3.18, 2.65, 3.10, 2.98, 2.70, 2.38, and 2.00 eV for CBB, CTF, and CC-X (X = 170, 220, 270, 320, and 370). Figure 8 The MS curves of CBB, CTF, and CC-X (X = 170, 220, 270, 320, and 370) are shown. From the MS curves, the flat-band potentials of CBB, CTF, and CC-X (X = 170, 220, 270, 320, and 370) can be calculated as 1.40, -0.46, 1.15, 0.89, 0.99, 0.94, and 0.99 (V vs NHE). Based on the band gap and MS curves, the electronic structures of BB, CTF, and CC-X (X = 170, 220, 270, 320, and 370) can be calculated (e.g., ...). Figure 9 (As shown). From Figure 9 As can be seen, the electronic structure of composite materials is affected by the calcination temperature, and different electronic structures will produce different free radicals. Therefore, the free radicals produced can be controlled by adjusting the temperature.

[0075] Experiment on the photocatalytic cleavage of lignin model compound (pp-ol) using composite photocatalyst:

[0076] A PP-OL solution with an initial concentration of 100 mg / L was prepared. The composite photocatalyst obtained in the example and the CBB and CTF composite materials were added to the PP-OL solution at an addition amount of 2.5 g / L, respectively. Adsorption was carried out under dark reaction conditions until saturation (4 hours). The adsorption was then measured using visible light (light power density: 17 mW / cm²). 2 After 6 hours of irradiation, samples were taken to detect and analyze the conversion rate of PP-OL and the yield of the product.

[0077] The results are as follows Figure 10 As shown, the main products of photocatalytic cracking are phenyl formate, benzaldehyde, benzoic acid, and 2-phenoxy-1-acetophenone. For CTF, the yields of benzoic acid and phenyl formate are 6.03% and 5.63%, respectively. CBB can only oxidize PP-ol to 2-phenoxy-1-acetophenone, but cannot further decompose it. With increasing calcination temperature, the yield of 2-phenoxy-1-acetophenone gradually decreases, while the yields of benzaldehyde, benzoic acid, and phenyl formate gradually increase. The highest yields are reached at a calcination temperature of 270℃, where the conversion rate of PP-ol is 100%, the yield of benzaldehyde is 64%, and the yield of phenyl formate is 70%. The yield calculation formulas are as follows:

[0078]

[0079] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing a perovskite quantum dot / triazine framework material CTF composite photocatalyst, characterized in that, The Cs3Bi2Br9 quantum dot-CTF complex is synthesized by simultaneously combining CTF with cesium, bismuth, and bromine sources using a molten salt method. The temperature of the molten salt method is 170~320 ℃, and the mass ratio of CTF to cesium source is 1~10:

1. The molten salt used in the molten salt method is one or more of KNO3, NaNO3, and KBr.

2. The preparation method of the perovskite quantum dot / triazine framework material CTF composite photocatalyst as described in claim 1, characterized in that, The cesium source is cesium bromide; The bismuth source is bismuth tribromide; The bromine source is bismuth tribromide and cesium bromide.

3. The preparation method of the perovskite quantum dot / triazine framework material CTF composite photocatalyst as described in claim 1, characterized in that, The cesium source, bismuth source, and bromine source are CsBr and BiBr3, with a molar ratio of CsBr to BiBr3 of 1:0.5~1.

5.

4. The preparation method of the perovskite quantum dot / triazine framework material CTF composite photocatalyst as described in claim 1, characterized in that, CTF is ground uniformly with cesium source, bismuth source, bromine source and molten salt, and then heated to 170~320 ℃ to melt the molten salt, and compounding and synthesis are carried out at the same time.

5. The preparation method of the perovskite quantum dot / triazine framework material CTF composite photocatalyst as described in claim 1, characterized in that, The temperature for the molten salt method is 220~320 ℃.

6. The preparation method of the perovskite quantum dot / triazine framework material CTF composite photocatalyst as described in claim 5, characterized in that, The temperature for the molten salt method is 250~290 ℃.

7. The preparation method of the perovskite quantum dot / triazine framework material CTF composite photocatalyst as described in claim 1, characterized in that, The molten salt used in the molten salt method is a mixture of KNO3, NaNO3 and KBr; the molar ratio of KNO3, NaNO3 and KBr is 1:0.4~0.6:0.4~0.

6.

8. A perovskite quantum dot / triazine framework material CTF composite photocatalyst, characterized in that, Obtained by the preparation method according to any one of claims 1 to 7.

9. The application of the perovskite quantum dot / triazine framework material CTF composite photocatalyst as described in claim 8 in the photocatalytic degradation of lignin.

10. A method for photocatalytic degradation of lignin to prepare aromatic monomers, characterized in that, The perovskite quantum dot / triazine framework material CTF composite photocatalyst described in claim 8 was added to a lignin-containing solution and subjected to phototreatment.

11. The method for preparing aromatic monomers by photocatalytic degradation of lignin as described in claim 10, characterized in that, The concentration of perovskite quantum dot / triazine framework material CTF composite photocatalyst is 2.0~3.0 g / L; The lignin-containing solution contains a lignin model compound.

12. The method for preparing aromatic monomers by photocatalytic degradation of lignin as described in claim 11, characterized in that, The lignin model compound is 2-phenoxy-1-phenylethanol.

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