AgI / Cs3Bi2X9 composite photocatalyst, preparation method thereof and application of AgI / Cs3Bi2X9 composite photocatalyst in photocatalytic aromatic hydrocarbon ammoxidation
By using AgI/Cs3Bi2X9 composite photocatalyst to perform aromatic hydrocarbon ammonia oxidation under mild conditions, the problem of difficult to achieve high selectivity and efficiency in the synthesis of nitrile compounds in the prior art is solved, and high selectivity and high stability photocatalysis is achieved Reaction, with the characteristics of green and environmental protection.
Patent Information
- Application Number
- CN202411673182.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-21
- Publication Date
- 2025-02-25
AI Technical Summary
The prior art is difficult to achieve high selectivity and efficient nitrile compound synthesis under mild conditions in aromatic hydrocarbon ammonia oxidation, and high temperature, high pressure or expensive ammonia sources are often required.
AgI/Cs3Bi2X9 composite photocatalyst is used, which forms a composite material with a mass ratio of 10-40% AgI for photocatalytic aromatic hydrocarbon ammonia oxidation by dissolving CsBr, BiBr3 and AgI in DMSO and precipitating in isopropanol. .
It realizes high selectivity (long-term selectivity up to 98%) in mild conditions to produce aromatic nitriles. The process is simple, low-cost and green and environmentally friendly.
Smart Images
Figure CN119500195A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to an AgI / Cs3Bi2X9 composite photocatalyst and a preparation method thereof and application in photocatalytic aromatic hydrocarbon ammoxidation, belonging to the technical field of photocatalytic preparation of chemicals. Background Art
[0002] The nitrile group is a ubiquitous functional group in organic synthesis and can be easily used for functional group transformations, including the formation of amines, amides, acids, aldehydes, and heterocycles. Aromatic nitriles, in particular, are widely used in the synthesis of natural products, materials, pesticides, and fuels. There are many synthetic routes for aromatic nitriles, including the traditional Sandmeyer reaction and the Rosenmund-von Braun reaction, in which the highly toxic Cu(I) cyanide is used as a cyanating agent. Other synthetic routes have also been reported, such as the cyanation of halogenated aromatics, the reaction of aromatic aldehydes or carboxylic acids with amino compounds, the dehydration of amides or aldoximes, and the ammoxidation of benzyl alcohol. Gas-phase ammoxidation of CH bonds on V-Cr oxide is an industrial route with high selectivity for nitriles, but requires a high temperature of 350°C. In recent years, it has been reported that heterogeneous manganese oxide catalysts have been successfully used for liquid-phase ammoxidation of CH bonds, and there is also a nano manganese oxide catalyst fixed on a zeolite-1 crystal. In the process of oxidative cyanation with O2 and urea, the catalyst shows good selectivity for nitrile, but these all require high pressure conditions. At the same time, it has been reported that a nitrile compound can be obtained under mild conditions using an organic dye as a catalyst, but the ammonia source used is hydroxylamine, which is more expensive. Therefore, from the perspective of environmental friendliness and economic benefits, it is of great significance to develop a green and stable method for synthesizing nitrile compounds.
[0003] Photocatalysis is a new and effective green technology. Semiconductor photocatalysis is considered to be an effective way to solve energy and environmental problems. Cs3Bi2X9 is a typical inorganic halide perovskite structure semiconductor. Due to its low toxicity and excellent chemical stability, it has attracted widespread attention in the field of photoluminescence and photocatalysis. At present, it has been reported that Cs3Bi2Br9 can be used to activate Csp3Bi2Br9 in toluene oxidation. 3 -H bond reaction system, a highly selective product is obtained. At the same time, in the field of photocatalysis, Cs3Bi2X9 is widely used in CO2 reduction, air pollutant purification, dye degradation and organic conversion. AgI materials have good conductivity and visible light absorption capacity, and have also received extensive attention in the field of photocatalysis. Compared with most semiconductor materials, AgI has a more negative conduction band potential. Combining it with other materials can effectively promote the separation of carriers. Summary of the invention
[0004] The purpose of the present invention is to explore a composite catalyst with high photocatalytic performance, which can realize highly selective cyanation of aromatic hydrocarbons under mild conditions.
[0005] The technical scheme adopted by the present invention is: a method for preparing an AgI / Cs3Bi2X9 composite photocatalyst, wherein three halide salts, CsBr, BiBr3 and AgI, are simultaneously dissolved in a DMSO solvent, stirred until completely dissolved, and then added dropwise to isopropanol while stirring to obtain a yellow precipitate, the precipitate is centrifuged and washed with isopropanol, and then dried to obtain an AgI / Cs3Bi2X9 composite photocatalyst, and the molar ratio of CsBr to BiBr3 is controlled to be around 3:2 to form a Cs3Bi2X9 material.
[0006] Preferably, the mass ratio of AgI in the AgI / Cs3Bi2X9 composite photocatalyst is 10-40%.
[0007] Preferably, the isopropanol centrifugal washing conditions are 5000 rpm-9000 rpm, and centrifugation for 3-5 minutes.
[0008] Preferably, drying means placing the precipitate in an oven and drying it at 100° C. for more than 24 hours.
[0009] The invention also discloses an AgI / Cs3Bi2X9 composite photocatalyst, which is composited by AgI and Cs3Bi2X9, wherein the mass ratio of AgI is 10-40%.
[0010] The present invention also discloses the application of the aforementioned AgI / Cs3Bi2X9 composite photocatalyst in photocatalytic aromatic hydrocarbon ammoxidation.
[0011] The present invention also discloses the application of the aforementioned AgI / Cs3Bi2X9 composite photocatalyst in the photocatalytic preparation of aromatic nitrile from methyl aromatic hydrocarbons.
[0012] Preferably, in the aforementioned AgI / Cs3Bi2X9 composite photocatalyst in methyl aromatic hydrocarbons, under the condition of light source irradiation, the C (sp 3 )-H bond is activated to generate aromatic nitrile in an ammonia-oxygen atmosphere. The reaction formula is shown in the following formula (1):
[0013]
[0014] The reaction temperature is above 80°C, the reaction atmosphere is a mixture of ammonia and oxygen (the oxygen ratio can be from 20% to 80%), and the total gas pressure can be above 1 bar. The light source includes monochromatic light or composite light in the λ<550nm band to produce a photocatalytic effect.
[0015] Preferably, the methyl aromatic hydrocarbon is toluene.
[0016] The beneficial effects of the present invention are as follows:
[0017] (1) The preparation method is based on Cs3Bi2X9, and AgI is distributed in Cs3Bi2X9. The entire preparation process is simple, the conditions are controllable, and the cost is low.
[0018] (2) The prepared AgI / Cs3Bi2X9 composite photocatalyst has a special adsorption effect on ammonia, and achieves high selectivity in liquid-phase methyl aromatic hydrocarbon ammoxidation to obtain aromatic nitrile under visible light. Using this composite catalyst, the long-term selectivity for aromatic nitrile obtained by cyanation of methyl aromatic hydrocarbon is as high as 98%.
[0019] (3) The two visible light photocatalysts, Cs3Bi2X9 and AgI, were combined in the route of aromatic hydrocarbon nitrilation to achieve highly selective and stable photocatalytic aromatic hydrocarbon ammoxidation under mild conditions. This is green and environmentally friendly with obvious advantages. The composite catalyst can be further scaled up to obtain gram-level high-purity products, demonstrating its potential for industrial applications. BRIEF DESCRIPTION OF THE DRAWINGS
[0020] Figure 1 , scanning tunneling electron microscopy (STEM) images and energy dispersive X-ray spectroscopy (EDS) spectra of the catalyst sample prepared in Example 1.
[0021] Figure 2 , X-ray diffraction characterization data of the catalyst sample prepared in Example 1.
[0022] Figure 3 , Gas chromatography (GC) diagram of the product in Example 2.
[0023] Figure 4 , the relationship between the photocatalytic performance in Example 3 and the AgI content in the photocatalyst.
[0024] Figure 5 , Gas chromatography (GC) diagram of the product in Example 4. DETAILED DESCRIPTION
[0025] The present invention is further illustrated by examples below, but is not intended to be limiting of the present invention. The specific materials used in the embodiments of the present invention and their sources are provided below. However, it should be understood that these are merely exemplary and are not intended to limit the present invention, and materials identical or similar to the types, models, qualities, properties or functions of the following reagents and instruments can be used to implement the present invention. The experimental methods used in the following examples are conventional methods unless otherwise specified. The materials, reagents, etc. used in the following examples, unless otherwise specified, can all be obtained from commercial sources.
[0026] Example 1: Preparation of photocatalyst AgI / Cs3Bi2Br9
[0027] Taking the photocatalyst 20% AgI / Cs3Bi2Br9 as an example, the anti-solvent method is used for synthesis. The specific preparation method is as follows:
[0028] Weigh 0.64g CsBr, 0.9g BiBr3 and 0.39g AgI and dissolve them in 10mL dimethyl sulfoxide solvent. Stir until completely dissolved, then slowly drop into 50mL isopropanol while stirring to obtain a yellow precipitate. The precipitate is centrifuged and washed with isopropanol, and the precipitate is dried in an oven at 100°C for 24h to obtain a 20% AgI / Cs3Bi2Br9 composite material. The amount of AgI used can be changed to obtain composite catalysts of different proportions. The scanning tunneling electron microscope (STEM) image of the catalyst sample prepared in Example 1 is shown in FIG. Figure 1 The X-ray diffraction characterization data are shown in Figure 2 As shown, from Figure 1 It can be seen that Cs3Bi2Br9 and AgI are block particles. Figure 2 It can be seen that the prepared composite material is consistent with the standard card peaks of Cs3Bi2Br9 and AgI, indicating that the composite material is composed of two phases, Cs3Bi2Br9 and AgI.
[0029] Example 2: Preparation of benzonitrile
[0030] Preparation of benzonitrile: Weigh 50 mg of 20% AgI / Cs3Bi2Br9 into a 20 mL stainless steel reactor with a glass window, add 5 mL of toluene, introduce 60% NH3 and 40% O2, total pressure 5 bar, raise the temperature to 120°C, turn on the 450 nm LED light source, and irradiate the reaction through the glass window for 20 hours. After the reaction is completed, turn off the light source.
[0031] The gas chromatography (GC) of the product is shown in Figure 3 As shown. The yield of each product (such as benzonitrile) and the selectivity of benzonitrile can be calculated based on the peak area of each substance. In this embodiment, the yield of benzonitrile is 300 μmol and the selectivity is 92%. If the reaction time is extended, the selectivity of benzonitrile can be continuously improved and can exceed 98% (after 80 hours).
[0032] The reaction formula of the above reaction is shown in the following formula (2):
[0033]
[0034] Example 3
[0035] When other conditions remain unchanged, the light source is changed to 410nm, and the yield of benzonitrile is 240μmol, and the selectivity is 84%. When the pressure is adjusted to 1bar, the yield of benzonitrile is 140μmol, and the selectivity is 34%. When the reaction temperature is adjusted to 80℃, the yield of benzonitrile is 130μmol, and the selectivity is 88%. When the oxygen concentration is adjusted to 20%, the yield of benzonitrile is more than 250μmol, and the selectivity is 91%. When the oxygen concentration is adjusted to 80%, the yield of benzonitrile is more than 280μmol, and the selectivity is 89%.
[0036] When other conditions remain unchanged, the relationship between the yield and selectivity of the product and the content of AgI in the photocatalyst is as follows: Figure 4 As shown. It can be seen that the mass proportion of AgI between 10% and 40% can maintain high selectivity and yield, while the yield and selectivity of pure Cs3Bi2Br9 are relatively low; pure AgI has a higher yield, lower selectivity, and AgI is unstable.
[0037] Example 4: Preparation of p-Fluorobenzonitrile
[0038] The preparation steps and conditions were the same as those in Example 2, except that the raw material was replaced with 5 mL of p-fluorotoluene.
[0039] The gas chromatography (GC) of the product is shown in Figure 5 The yield and selectivity of p-fluorobenzonitrile can be calculated based on the peak area of each substance. In this embodiment, the yield of p-fluorobenzonitrile is 170 μmol and the selectivity is 82%.
[0040] The reaction formula of the above reaction is shown in the following formula (3):
[0041]
[0042] In summary, the present invention prepares a composite photocatalyst that can be used to prepare nitrile organic chemicals. The AgI / Cs3Bi2Br9 composite photocatalyst provided by the present invention can realize liquid-phase aromatic hydrocarbon ammoxidation under visible light; and the catalyst has high selectivity and long-term stability under the condition of sufficient reaction gas, and has the potential for industrial application.
Claims
1. A method for preparing a AgI / Cs3Bi2X9 composite photocatalyst, characterized in that: The three halide salts CsBr, BiBr3 and AgI were dissolved in DMSO solvent at the same time, and the molar ratio of CsBr to BiBr3 was controlled to be around 3:
2. After stirring until completely dissolved, they were added dropwise to isopropanol while stirring to obtain a precipitate. The precipitate was washed by centrifugation with isopropanol and then dried to obtain an AgI / Cs3Bi2X9 composite photocatalyst.
2. The preparation method according to claim 1, characterized in that Ag The mass ratio of AgI in the I / Cs3Bi2X9 composite photocatalyst is 10-40%.
3. The preparation method according to claim 1, characterized in that: The conditions for isopropanol centrifugal washing are 5000rpm-9000rpm, and centrifugation for 3-5 minutes.
4. The preparation method according to claim 1, characterized in that: Drying means placing the precipitate in an oven and drying it at 100°C for more than 24 hours.
5. An AgI / Cs3Bi2X9 composite photocatalyst, which is composed of AgI and Cs3Bi2X9, wherein the mass ratio of AgI is 10-40%.
6. Use of the AgI / Cs3Bi2X9 composite photocatalyst described in claim 5 in photocatalytic aromatic hydrocarbon ammoxidation.
7. Use of the AgI / Cs3Bi2X9 composite photocatalyst according to claim 5 in the photocatalytic preparation of aromatic nitrile from methyl aromatic hydrocarbons.
8. The use according to claim 7, characterized in that The AgI / Cs3Bi2X9 composite photocatalyst as claimed in claim 5 is added to methyl aromatic hydrocarbons, and ammonia and oxygen mixed gas is introduced to react under the condition of light source irradiation to obtain aromatic nitrile.
9. The use according to claim 7 or 8, characterized in that: The methyl aromatic hydrocarbon is toluene.
10. The use according to claim 8, characterized in that: The reaction temperature is above 80° C., the reaction atmosphere is a mixture of ammonia and oxygen in which the oxygen accounts for 20%-80%, and the total gas pressure is above 1 bar.