MnOX / In2O3 composite material, preparation method thereof and application of MnOX / In2O3 composite material in selective photocatalytic ammoxidation of aromatic hydrocarbon
Through the preparation of MnOX/In2O3 composite materials and photocatalytic technology, the problem of high temperature and high pressure of traditional synthetic nitrile compounds is solved, and efficient and environmentally friendly aromatic ammonia oxidation is achieved under low temperature and normal pressure, providing a new method for green nitrile compounds.
Patent Information
- Application Number
- CN202411267146.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-11
- Publication Date
- 2024-12-20
AI Technical Summary
The prior art has problems with high costs, energy consumption and toxic waste production when synthesizing nitrile compounds, and traditional methods require high temperature and high pressure conditions, making it difficult to achieve green and mild synthesis.
The MnOX/In2O3 composite material is prepared by room temperature impregnation method. MnOX is distributed on the surface of In2O3, and the aromatic ammonia oxidation is achieved under photocatalytic conditions. The specific steps include mixing In2O3 and MnSO4·H2O solution, dropping in KMnO4 solution, suction filtration and drying, forming 0.4-4.8 wt.% MnOX/In2O3 composite material, and catalyzed methylaromatic hydrocarbons to form aromatic methylforminitrile under light source.
It realizes high selectivity and high conversion rate aromatic ammonia oxidation under low temperature and normal pressure conditions, reduces energy consumption, improves the economic and environmental protection of synthesis, and the catalyst has a small particle size and a large specific surface area, which is suitable for chemical production.
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Figure CN119158566A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to a MnO X / In2O3 composite material, preparation method thereof and application in selective photocatalytic aromatic hydrocarbon ammoxidation belong to the technical field of photocatalytic preparation of chemicals. Background Art
[0002] Benzonitrile compounds have important applications in the fields of medicine, agricultural chemicals, dyes and fine chemicals. The traditional synthesis methods of nitrile compounds mainly include Sandmeyer reaction, Wittig reaction, nucleophilic substitution reaction of aliphatic halogenated hydrocarbons or sulfonates, etc. However, these methods have disadvantages such as using high-cost raw materials, generating toxic wastes and poor atomic efficiency. In recent years, the "gas phase ammoxidation" method of alkyl aromatics is one of the most widely used methods for synthesizing aromatic nitrile compounds in industry. In industrial production, V-Cr oxide is used to prepare methyl aromatics into nitrile compounds under high temperature and high pressure. However, this method will lead to high energy consumption. Therefore, people are committed to developing new synthetic methods to achieve the synthesis of nitrile compounds under green and mild conditions. It is of great significance to realize the ammoxidation of methyl aromatics below the boiling point of aromatics and under normal pressure conditions.
[0003] In2O3 is an n-type semiconductor functional material with a wide bandgap, small resistivity and high catalytic activity. It has been widely used in the optoelectronic field, gas sensors and catalysts. In the field of photocatalysis, In2O3 can achieve functions such as pollutant degradation, hydrogen production and carbon dioxide reduction. Transition metal oxides, as a class of positively charged oxides with abundant catalytic sites, as well as their structural stability, chemical tunability and environmental friendliness, have attracted widespread attention. Among the many transition metal oxide catalysts, manganese-based oxides have been widely used in electrochemistry, chemical sensing and catalysis due to their unique properties such as multiple oxidation states, high abundance and low toxicity. In particular, their oxidation catalysis has attracted great interest, and many methods for the ammoxidation of alcohols to amides on manganese-based oxides have been recorded. With this in mind, we envision combining a semiconductor that can activate aromatics at low temperature and atmospheric pressure with manganese-based oxides to achieve photocatalytic aromatic ammoxidation under relatively green and mild conditions. Summary of the invention
[0004] The purpose of the present invention is to provide a MnO X Preparation method of / In2O3 composite material. X / In2O3 composites can be used for selective photocatalytic oxidation of aromatic hydrocarbons.
[0005] The technical solution adopted by the present invention is:
[0006] A MnO X / In2O3 composite materials, composed of MnO X Composited with In2O3, MnO X It accounts for 0.4-4.8wt.% in the composite material.
[0007] Preferably, the value of x is 1.3-1.5.
[0008] Preferably, MnO X The proportion in the composite material is 0.7-2.9wt.%, and more preferably 0.7wt.%.
[0009] The present invention also discloses the above-mentioned MnO X A method for preparing a / In2O3 composite material, the steps comprising:
[0010] (1) Mix In2O3 and MnSO4·H2O solution at room temperature and stir and immerse for more than 1 hour;
[0011] (2) Add an excess amount of KMnO4 solution until the solution turns purple, then stop adding and stir at room temperature for more than 1 hour;
[0012] (3) The reactant is filtered and washed until the washing liquid is neutral, and then dried to obtain MnO X / In2O3 composite materials.
[0013] Preferably, the concentration of the MnSO4·H2O solution in step (1) is 1-15 mg / mL, and the stirring and immersion time is 3 h; the concentration of the KMnO4 solution in step (2) is 1-5 mg / mL, and the stirring reaction time is 2 h.
[0014] Preferably, the drying in step (3) is specifically to dry the material in an oven at 80° C. for more than 12 hours.
[0015] The present invention also discloses the above-mentioned MnO X Application of / In2O3 composite materials in selective photocatalytic ammoxidation of aromatic hydrocarbons.
[0016] The present invention also discloses the above-mentioned MnO X Application of / In2O3 composite materials in catalyzing the preparation of aromatic nitriles from methyl aromatics.
[0017] Preferably, MnO is added to the methyl aromatic solution. X / In2O3 composite materials, in light sources and MnO X / In2O3 composite materials, C(sp 3 )-H bond is activated to generate aromatic nitrile in an ammonia-oxygen atmosphere.
[0018] The reaction formula is as follows (1):
[0019]
[0020] R can be H, F, Cl, Br, CH3, Et, OMe, CN, CF3.
[0021] Preferably, the light source is light including a wavelength band of λ<530nm. More preferably, the light source is a monochromatic violet light source with a wavelength of 410nm.
[0022] Preferably, the reaction temperature is 80° C., and the reaction gas is a mixed gas of 80% NH 3 and 20% O 2 at 1 bar.
[0023] The MnO prepared by the present invention X / In2O3 composite materials can selectively photocatalyze the ammoxidation of methyl aromatics, and the selectivity of the obtained aromatic nitriles can exceed 90%.
[0024] The beneficial effects of the present invention are as follows:
[0025] 1. The present invention provides MnO x Preparation method of / In2O3 composite material, with In2O3 as the main component and MnO x The whole preparation process is simple, the conditions are controllable, the cost is low, and the synthesized material has a small particle size (10-20nm), a large specific surface area (20.9m 2 / g) characteristics.
[0026] 2. MnO provided by the present invention x The / In2O3 composite material has a coupling effect and can realize the liquid-phase methyl aromatic ammoxidation under visible light, especially the aromatic ammoxidation under low temperature and normal pressure conditions; and the catalyst has high selectivity and conversion rate under the condition of sufficient reaction raw material gas, and has the potential for practical application.
[0027] 3. In2O3, a substance that can activate aromatic hydrocarbons, is combined with MnO x The mixture achieved high selectivity and high conversion rate of photocatalytic aromatic ammoxidation at normal pressure, providing a new idea for further reducing the temperature of aromatic ammoxidation reaction. BRIEF DESCRIPTION OF THE DRAWINGS
[0028] Figure 1 This is a transmission electron microscope (TEM) image of the photocatalyst prepared in Example 1 of the present invention.
[0029] Figure 2 This is the X-ray diffraction data (XRD) of the catalyst in Example 1 of the present invention.
[0030] Figure 3 The yield of the catalyst product in Example 2 of the present invention increases with the increase of MnOx Changes in load.
[0031] Figure 4 The yield of the catalyst product in Example 2 of the present invention changes at different wavelengths.
[0032] Figure 5 This is the GC of the catalyst product in Example 2 of the present invention. DETAILED DESCRIPTION
[0033] 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.
[0034] (1) Example 1: Preparation of photocatalyst
[0035] Photocatalyst 0.7% MnO x / In2O3 is taken as an example, and its preparation method is as follows:
[0036] MnO x / In2O3 composite catalyst was synthesized by wet impregnation method. 1.6g In2O3 with a particle size of 10-20nm was mixed with a MnSO4·H2O solution containing 15mg of solute (especially, when the concentration of MnSO4·H2O solution was 1.5mg / mL, 10mL was used). After 3h of stirring and impregnation, an excess of KMnO4 solution (concentration <5mg / mL) was slowly dripped in until the solution turned purple and the dripping was stopped. After 2h of stirring, the obtained material was filtered and washed with deionized water until the solution was neutral, and the material was dried in an oven at 80℃ for 12h to obtain 0.7wt.% MnO x / In2O3 composite materials.
[0037] Change the concentration of MnSO4·H2O solution (when the total solution volume is 10mL, 0.7% MnO x / In2O3 requires 15mg MnSO4·H2O, and the amount of MnSO4·H2O solution required for other loading amounts can be obtained. For example, 0.4% MnO x / In2O3 requires 8.6mg MnSO4·H2O, 2.9% MnO x / In2O3 requires 60mg MnSO4·H2O) to obtain composite catalysts with different loading ratios. X is between 1.3-1.5. x The transmission electron microscope image of the / In2O3 composite catalyst is shown in Figure 1 ,from Figure 1 It can be seen that its particle size is mainly distributed in 10-20nm, and the XRD data is shown in Figure 2 . After testing, its specific surface area is 20.9m 2 / g.
[0038] It is also possible to directly purchase commercial nano-scale In2O3 for the preparation of MnOx / In2O3 composite materials. The particle size of the composite material is basically consistent with the particle size of In2O3 used as the raw material, and it can also achieve high-selectivity and high-conversion photocatalytic aromatic ammoxidation at normal pressure.
[0039] (2) Example 2: Preparation of benzonitrile
[0040] Preparation of benzonitrile: weigh 170 mg MnO x / In2O3 in a 350mL transparent reactor, add 15ml toluene, pass ammonia oxygen mixed gas (ratio of 20% O2 + 80% NH3), replace the entire interior of the reactor with ammonia oxygen mixed gas, heat to 80°C, turn on the 410nm LED light source to irradiate the reaction for 12h. After the reaction is completed, turn off the light source, centrifuge the reaction mixture, pour out the supernatant, filter the catalyst solid with a filter membrane to obtain the liquid after the reaction, which mainly contains the product benzonitrile and unreacted toluene, which can be separated by distillation to obtain benzonitrile with higher purity. The obtained product was tested for performance by GC, GC-MS, etc. The yield and selectivity of the target product increased with MnO x / In2O3 loading changes in the relationship shown in Figure 3 , GC test data see Figure 4 . 0.11g*g of benzonitrile can be obtained cat -1 *day -1 (Per gram of catalyst, photocatalytic reaction can produce 0.11g of benzonitrile per day), selectivity>95%. The selectivity of the above reaction formula and its corresponding product is shown in the following formula (2):
[0041]
[0042] (3) Example 3: Preparation of 4-fluorobenzonitrile
[0043] Preparation of 4-fluorobenzonitrile: weigh 170 mg of MnO x / In2O3 in a reactor, add 15ml 4-fluorotoluene, pass ammonia oxygen mixed gas (ratio of 20% O2 + 80% NH3) and mix for 3 minutes, then return to normal pressure, turn on the 410nm LED light source, heat the oil bath to 80°C, and irradiate the reaction for 12 hours. After the reaction is completed, turn off the light source, centrifuge the reaction mixture, pour out the supernatant, filter the catalyst solid with a filter membrane to obtain the liquid after the reaction, which mainly contains the product 4-fluorobenzonitrile and unreacted 4-fluorotoluene. The obtained product was tested for performance by GC, GC-MS, etc., and 0.15g*g of 4-fluorobenzonitrile was obtained. cat -1 *day -1 (Each gram of catalyst can produce 0.15g of 4-fluorobenzonitrile per day of photocatalytic reaction), selectivity>98%. The selectivity of the above reaction formula and its corresponding product is shown in the following formula (3):
[0044]
[0045] The above provides an embodiment in which R is F or H. R can also be other groups such as Cl, Br, CH3, Et, OMe, CN, CF3, etc. The operation is no different from that of Examples 2 and 3.
[0046] In summary, the MnO x The / In2O3 composite material has a coupling effect and can realize liquid-phase aromatic ammoxidation under visible light; and the catalyst has high selectivity and conversion rate under the condition of sufficient gas, has the potential for practical application, and solves the drawbacks of high temperature and high pressure in current production. Due to the milder reaction conditions, the new method of the present invention can prepare a series of nitrile organic compounds, which can be applied in chemical production, chemical reaction mechanism and other aspects.
Claims
1. A MnO X / In2O3 composite material, characterized in that MnO X Composited with In2O3, MnO X It accounts for 0.4-4.8wt.% in the composite material.
2. MnO according to claim 1 X / In2O3 composite material, characterized in that The value of x is 1.3-1.
5.
3. MnO according to claim 1 or 2 X / In2O3 composite material, characterized in that MnO X It accounts for 0.7-2.9wt.% in the composite material.
4. MnO according to any one of claims 1 to 3 X / In2O3 composite material preparation method, characterized in that The steps include: (1) Mix In2O3 and MnSO4·H2O solution at room temperature and stir and immerse for more than 1 hour; (2) Add an excess amount of KMnO4 solution until the solution turns purple, then stop adding and stir at room temperature for more than 1 hour; (3) The reactant is filtered and washed until the washing liquid is neutral, and then dried to obtain MnO X / In2O3 composite materials.
5. The preparation method according to claim 4, characterized in that: The concentration of the MnSO4·H2O solution in step (1) is 1-15 mg / mL; the concentration of the KMnO4 solution in step (2) is 1-5 mg / mL.
6. The preparation method according to claim 5, characterized in that: The drying in step (3) is specifically to dry the material in an oven at 80° C. for more than 12 hours.
7. MnO according to any one of claims 1 to 3 X Application of / In2O3 composite materials in selective photocatalytic ammoxidation of aromatic hydrocarbons.
8. MnO as claimed in any one of claims 1 to 3 X Application of / In2O3 composite materials in catalyzing the preparation of aromatic nitriles from methyl aromatics.
9. The use according to claim 8, characterized in that: Add MnO to the aromatic solution X / In2O3 composite materials, in light sources and MnO X / In2O3 composite material catalytic conditions, aromatic nitrile is generated in an ammonia-oxygen atmosphere, of which ammonia accounts for 10%-90%.
10. The use according to claim 8, characterized in that: The light source contains light in the wavelength band of λ<530nm.