Alkali metal modified manganese metal oxide catalyst, and preparation method and application thereof
By preparing nano-flower-shaped alkali metal-modified manganese metal oxide catalysts, the problems of low conversion efficiency and selectivity of HMF to FFCA and FDCA were solved, and a highly efficient catalytic effect was achieved.
Patent Information
- Application Number
- CN202410969748.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2024-07-19
- Publication Date
- 2025-12-12
- Estimated Expiration
- 2044-07-19
AI Technical Summary
Existing catalysts exhibit low conversion efficiency and selectivity when converting 5-hydroxymethylfurfural (HMF) to 5-formyl-2-furancarboxylic acid (FFCA) and 2,5-furandicarboxylic acid (FDCA).
Alkali metal-modified manganese oxide catalysts were prepared by co-precipitation reaction, using soluble manganese metal salts and permanganate in aqueous solution to form nano-flower-like structures, increasing active sites and optimizing the electronic environment. Alkali metal ions were added to improve the stability of the catalyst.
High conversion and selectivity of HMF to FFCA and FDCA were achieved. The catalyst exhibited excellent stability under high temperature and corrosive environments, and the catalytic efficiency was significantly improved.
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Figure CN119114057B_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of catalysts, in particular to an alkali metal modified manganese metal oxide catalyst and a preparation method and application thereof. BACKGROUND
[0002] 5-hydroxymethylfurfural (HMF) is an important platform compound extracted from biomass, which is a key bridge connecting biomass and high-value chemicals / fuels. The preparation of HMF and its derivatives 5-formyl-2-furoic acid (FFCA) and 2,5-furan dicarboxylic acid (FDCA) has attracted widespread attention, and these compounds have important applications in bioplastics, solvents, drugs and other fine chemical products.
[0003] HMF can be converted into FFCA and FDCA by catalytic oxidation reaction. The catalysts currently used can be divided into two categories, namely noble metal catalysts (such as palladium or platinum) and non-noble metal catalysts (such as manganese or iron-based catalysts). These catalysts can effectively oxidize the hydroxymethyl group of HMF to carboxyl group, thereby obtaining FFCA. Further oxidation can convert FFCA into FDCA, and the preparation of FDCA usually involves stronger oxidation conditions or more effective catalytic systems.
[0004] Although the existing catalysts can realize the conversion of HMF into FFCA and FDCA, they generally have the problem of low conversion efficiency and selectivity. Therefore, it is of great significance to develop a new catalyst to improve the conversion efficiency and selectivity of HMF for the development of HMF catalytic oxidation technology. SUMMARY
[0005] In view of the deficiencies of the prior art, the purpose of the present application is to develop a highly efficient catalyst to improve the conversion efficiency and selectivity of HMF.
[0006] To solve the above technical problems, the present application provides a preparation method of an alkali metal modified manganese metal oxide catalyst, comprising the following steps:
[0007] S1, dissolving a manganese metal salt in ionized water to obtain solution A, wherein the manganese metal salt is selected from one or more of MnCl2, MnBr2, Mn(NO3)2, MnSO4 and Mn(CH3COO)2;
[0008] S2, dissolving a permanganate in ionized water to obtain solution B, wherein the permanganate is selected from one or more of KMnO4, NaMnO4 and LiMnO4;
[0009] S3, adding solution B dropwise to solution A and stirring to perform a co-precipitation reaction;
[0010] S4, collecting the precipitate obtained in the reaction, filtering, washing, and drying to obtain the alkali metal modified manganese metal oxide catalyst.
[0011] The alkali metal modified manganese metal oxide catalyst is prepared by using a soluble manganese metal salt and a soluble permanganate as raw materials and water as a solvent through a co-precipitation reaction.
[0012] Further, in the solution A, the concentration of the manganese metal salt is 1-10 mol / L.
[0013] Further, in the solution B, the concentration of the permanganate is 1-10 mol / L.
[0014] Further, in the step S3, the volume ratio of the solution A to the solution B added dropwise is 1:0.5-1:2.
[0015] The manganese metal salt solution and the permanganate solution with specific solubility and ratio are reacted to control the structure of the product, and a manganese oxide nanoflower catalyst intercalated with alkali metal ions (Li + , Na + , K + ) is obtained.
[0016] Further, in the step S3, the reaction time is 1-6 hours.
[0017] Further, in the step S4, the drying temperature is 60-100 DEG C, and the time is 6-12 h.
[0018] The second aspect of the application provides an alkali metal modified manganese metal oxide catalyst prepared by the above preparation method, wherein the alkali metal modified manganese metal oxide catalyst has a nanoflower spherical structure. The nanoflower spherical structure makes the catalyst have a very high specific surface area, increases the number of active sites, and thus improves the catalytic efficiency; the intercalation of alkali metal ions further optimizes the electronic environment of the active sites, which is conducive to enhancing the activity of the catalyst.
[0019] The third aspect of the application provides an application, wherein the alkali metal modified manganese metal oxide catalyst is used for catalyzing the oxidation of 5-hydroxymethylfurfural.
[0020] Further, in the 5-hydroxymethylfurfural aqueous solution, a persulfate (PMS) and the alkali metal modified manganese metal oxide catalyst are added, and the mixed solution is heated or subjected to light irradiation, so that the 5-hydroxymethylfurfural is converted into target products, and the target products are 5-formyl-2-furoic acid and / or 2,5-furan dicarboxylic acid.
[0021] Further, the reaction time required for catalytic oxidation of 5-hydroxymethylfurfural to generate the target product is 0.5-12 h.
[0022] Under the condition of no alkali, PMS is used as an oxidant, and an alkali metal modified manganese metal oxide catalyst is added, so that HMF can be efficiently converted, and the catalyst has high selectivity for the reaction path of oxidation of HMF into FFCA and FDCA.
[0023] Compared with the prior art, the present application has the following beneficial effects:
[0024] The present application prepares a manganese metal oxide catalyst through a coprecipitation reaction, introduces a certain amount of alkali metal ions, increases the content of oxygen vacancies in the catalyst, changes the morphology, material structure and electronic environment of the catalyst, increases the number of active sites, and improves the catalytic ability of the catalyst. BRIEF DESCRIPTION OF DRAWINGS
[0025] Figure 1 The X-ray diffraction pattern of the catalyst prepared in Example 1, Example 2 and Example 3 of the present application.
[0026] Figure 2 The electron paramagnetic resonance spectrum of the catalyst prepared in Example 1, Example 2 and Example 3 of the present application.
[0027] Figure 3 The transmission electron microscope image of the catalyst prepared in Example 1 of the present application.
[0028] Figure 4 The transmission electron microscope image of the catalyst prepared in Example 2 of the present application.
[0029] Figure 5 The transmission electron microscope image of the catalyst prepared in Example 3 of the present application.
[0030] Figure 6 The photocatalytic (left) and thermal catalytic (right) effect diagram of the catalyst prepared in Example 1 of the present application on HMF.
[0031] Figure 7 The photocatalytic (left) and thermal catalytic (right) effect diagram of the catalyst prepared in Example 2 of the present application on HMF.
[0032] Figure 8 The photocatalytic (left) and thermal catalytic (right) effect diagram of the catalyst prepared in Example 3 of the present application on HMF. DETAILED DESCRIPTION
[0033] In order to make the above objectives, characteristics and advantages of the present application more obvious and easy to understand, the specific embodiments of the present application are described in detail below with reference to the drawings.
[0034] It should be understood that the terms described in the present application are only for describing the specific embodiments and are not intended to limit the present application. In addition, for the numerical range in the present application, it should be understood that each intermediate value between the upper limit and the lower limit of the range is also specifically disclosed. Each smaller range between any stated value or stated range and any other stated value or intermediate value within the stated range is also included in the present application. The upper limit and the lower limit of these smaller ranges can be independently included or excluded from the range.
[0035] Many modifications and variations of the specific embodiments of the present application can be made without departing from the scope or spirit of the present application, which will be apparent to those skilled in the art. Other embodiments derived from the description of the present application will be apparent to the skilled person. The description and examples of the present application are only exemplary.
[0036] The specific embodiments of the present application provide a preparation method of an alkali metal modified manganese metal oxide catalyst, comprising the following steps:
[0037] S1, dissolving a soluble manganese metal salt in ionized water to obtain solution A. In specific embodiments, the manganese metal salt can be selected from MnCl2, MnBr2, Mn(NO3)2, MnSO4, Mn(CH3COO)2, etc.; in solution A, the concentration of the manganese metal salt is 1-10 mol / L.
[0038] S2, dissolving a soluble permanganate salt in ionized water to obtain solution B. In specific embodiments, the permanganate salt can be selected from KMnO4, NaMnO4, LiMnO4, which has alkali metal ions; in solution B, the concentration of the permanganate salt is 1-10 mol / L.
[0039] S3, adding solution B dropwise to solution A and stirring to perform a co-precipitation reaction. In specific embodiments, the volume ratio of solution A to the added solution B is 1:0.5-1:2, and the reaction time is 1-6 hours.
[0040] S4, collecting the precipitate obtained by the reaction, filtering, washing, and drying to obtain an alkali metal modified manganese metal oxide catalyst. Preferably, the drying conditions are at a temperature of 60-100℃ for 6-12 h.
[0041] The catalyst prepared by the above method has a nanoflower spherical structure, which increases the number of active sites, and has alkali metal ion intercalation, which optimizes the electronic environment of the active sites, making the catalyst have very high activity. The addition of alkali metal ions can enhance the stability of the catalyst under reaction conditions, making it more resistant to high temperature and corrosive environments.
[0042] The catalyst is used for catalyzing oxidation of 5-hydroxymethylfurfural, and high-efficiency conversion of HMF can be realized under an alkali-free condition by using a persulfate as an oxidant, and the reaction time required for generating a target product is 0.5-12 h, and the catalyst has high selectivity for a reaction path of oxidation of HMF into FFCA and FDCA.
[0043] The technical effects of the present application are described below in combination with specific examples. Unless otherwise specified, the raw materials in the examples of the present application are purchased through a commercial channel.
[0044] The performance testing method of the catalyst in each of the following examples and comparative examples is as follows:
[0045] I. Photocatalytic effect test: 9 milliliters of 20 millimoles of HMF aqueous solution and 1 milliliter of 100 millimoles of potassium persulfate aqueous solution are added to a reaction container, and then 50 milligrams of a catalyst is added. A full-spectrum light with an intensity of 500 milliwatts per square centimeter is provided, and after the light source is turned on, the timing and catalytic reaction are started. Every 20 minutes, 10 microliters of the reaction solution is taken, 990 microliters of water is added for dilution and filtration, and liquid chromatography is used to analyze the sample, and the whole reaction process lasts for 2 hours.
[0046] II. Thermal catalytic effect test: 9 milliliters of 20 millimoles of HMF aqueous solution and 1 milliliter of 100 millimoles of potassium persulfate aqueous solution are added to a reaction container, and then 50 milligrams of a catalyst is added. The reaction solution is heated to 55℃, and the timing and catalytic reaction are started. Every 20 minutes, 10 microliters of the reaction solution is taken, 990 microliters of water is added for dilution and filtration, and liquid chromatography is used to analyze the sample, and the whole reaction process lasts for 2 hours.
[0047] Example 1
[0048] (1) 30 mmol of Mn(NO3)2·4H2O is dissolved in 100 ml of deionized water, stirred uniformly, and fully dissolved to obtain solution A.
[0049] (2) 20 mmol of KMnO4 is dissolved in 100 ml of deionized water, stirred uniformly, and fully dissolved to obtain solution B.
[0050] (3) The B solution is added dropwise to the solution A, and fully stirred for 2 hours to obtain a brown precipitate.
[0051] (4) The obtained brown precipitate is filtered, washed, and dried at 60℃ for 12 hours to obtain a potassium ion modified manganese metal oxide catalyst.
[0052] To confirm the composition and morphology of the catalyst prepared in Example 1, X-ray diffraction and transmission electron microscope analysis were performed, and the results are shown in Figure 1 and Figure 3 As shown, the catalyst synthesized according to Example 1 has a low crystallinity MnO2 phase state, and the image in the transmission electron microscope presents a nanoflower spherical structure. Electron paramagnetic resonance spectroscopy analysis of the catalyst shows that the catalyst has a high concentration of oxygen vacancy content. Figure 2
[0053] The performance of the catalyst was tested, and its photocatalytic reaction effect on HMF is shown in Figure 6 (left), in which the conversion rate of HMF is 93.7% and the yield of FFCA is 81.6% and the yield of FDCA is 10.1% in 2 hours of catalytic reaction time; and its thermal catalytic reaction effect on HMF is shown in Figure 6 (right), in which the conversion rate of HMF is 97.6% and the yield of FFCA is 85.5% and the yield of FDCA is 10.9% in 2 hours of catalytic reaction time.
[0054] Example 2
[0055] (1) 20 mmol of MnSO4·4H2O was dissolved in 100 ml of deionized water, stirred uniformly, and fully dissolved to obtain solution A.
[0056] (2) 30 mmol of NaMnO4 was dissolved in 100 ml of deionized water, stirred uniformly, and fully dissolved to obtain solution B.
[0057] (3) The B solution was added dropwise to the solution A, and fully stirred for 3 hours to obtain a brown precipitate.
[0058] (4) The obtained brown precipitate was filtered, washed, and dried at 80°C for 10 hours to obtain a nanion-modified manganese metal oxide catalyst.
[0059] To confirm the composition and morphology of the catalyst prepared in Example 2, X-ray diffraction and transmission electron microscope analysis were performed, and the results are shown in Figure 1 and Figure 4 As shown, the catalyst synthesized according to Example 2 has a low crystallinity MnO2 phase state, and the image in the transmission electron microscope presents a nanoflower spherical structure. Electron paramagnetic resonance spectroscopy analysis of the catalyst shows that the catalyst has a high concentration of oxygen vacancy content. Figure 2
[0060] The performance of the catalyst was tested, and its photocatalytic reaction effect on HMF is shown inFigure 7 (Left) shows that the conversion rate of HMF is 98.8% and the yield of FFCA is 90.6% and the yield of FDCA is 8.7% within 2 hours of catalytic reaction time; the thermal catalytic reaction effect of HMF thereof is as shown in Figure 7 (Right) shows that the conversion rate of HMF is 99.9% and the yield of FFCA is 93.1% and the yield of FDCA is 4.4% within 2 hours of catalytic reaction time.
[0061] Example 3
[0062] (1) 50 mmol of MnCl2·4H2O was dissolved in 100 ml of deionized water, stirred uniformly, and allowed to be fully dissolved to obtain solution A.
[0063] (2) 40 mmol of LiMnO4 was dissolved in 80 ml of deionized water, stirred uniformly, and allowed to be fully dissolved to obtain solution B.
[0064] (3) The B solution was added dropwise to the solution A, and was fully stirred for 4 hours to obtain a brown precipitate.
[0065] (4) The obtained brown precipitate was filtered, washed, and dried at 100℃ for 6 hours to obtain a lithium ion-modified manganese metal oxide catalyst.
[0066] In order to confirm the composition and morphology structure of the catalyst prepared in Example 3, X-ray diffraction and transmission electron microscope analysis were performed, and the results are as shown in Figure 1 and Figure 5 As shown, the catalyst synthesized according to Example 3 has a low crystallinity MnO2 phase state, and the image in the transmission electron microscope presents a nanoflower spherical structure. Electron paramagnetic resonance spectrum analysis was performed on the catalyst, and the results are as shown in Figure 2 It can be seen that the catalyst has a high concentration of oxygen vacancy content.
[0067] The performance of the catalyst was tested, and the photocatalytic reaction effect of HMF thereof is as shown in Figure 8 (Left) shows that the conversion rate of HMF is 93.3% and the yield of FFCA is 74.7% and the yield of FDCA is 11.1% within 2 hours of catalytic reaction time; the thermal catalytic reaction effect of HMF thereof is as shown in Figure 8 (Right) shows that the conversion rate of HMF is 93.5% and the yield of FFCA is 75.7% and the yield of FDCA is 15.9% within 2 hours of catalytic reaction time.
[0068] Comparative Example 1
[0069] The commercial MnO2catalyst purchased is used as a comparative example, and the HMF photocatalysis and thermal catalysis experiments are carried out under the same conditions. The experimental results of the photocatalysis reaction show that, within 2 hours of the catalytic reaction time, the conversion rate of HMF is 66.2%, the yield of FFCA is 35.7%, and the yield of FDCA is 4.9%; the effect of the thermal catalysis reaction shows that, within 2 hours of the catalytic reaction time, the conversion rate of HMF is 71.3%, the yield of FFCA is 47.0%, and the yield of FDCA is 6.0%. It can be seen that the conversion efficiency and selectivity of the catalyst prepared in the above examples are greatly improved compared with the catalyst of the comparative example.
[0070] Although the present application discloses as above, the protection scope of the present application is not limited to this. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present application, and these changes and modifications shall fall within the protection scope of the present application.
Claims
1. Use of an alkali metal-modified manganese metal oxide catalyst, characterized in that, In a 5-hydroxymethylfurfural aqueous solution, a persulfate and an alkali metal modified manganese metal oxide catalyst is added, and the mixed solution is subjected to light irradiation, so that the 5-hydroxymethylfurfural is converted into a target product, which is 5-formyl-2-furancarboxylic acid and / or 2,5-furandicarboxylic acid; The preparation method of the alkali metal modified manganese metal oxide catalyst comprises the following steps: S1, dissolving a manganese metal salt in ionized water to obtain solution A, wherein the manganese metal salt is selected from one or more of MnCl2, MnBr2, Mn(NO3)2, MnSO4 and Mn(CH3COO)2, and the concentration of the manganese metal salt in the solution A is 1-10 mol / L; S2, dissolving a permanganate in ionized water to obtain solution B, wherein the permanganate is selected from one or more of KMnO4, NaMnO4 and LiMnO4, and the concentration of the permanganate in the solution B is 1-10 mol / L; S3, adding the solution B dropwise into the solution A, and stirring to perform a co-precipitation reaction, wherein the volume ratio of the solution A to the added solution B is 1:0.5-1:2; S4, collecting the precipitate obtained by the reaction, and filtering, washing and drying to obtain the alkali metal modified manganese metal oxide catalyst.
2. Use of an alkali-modified manganese metal oxide catalyst according to claim 1, characterized in that In the step S3, the reaction time is 1-6 hours.
3. Use of an alkali metal-modified manganese metal oxide catalyst according to claim 1, characterized in that In the step S4, the drying temperature is 60-100℃, and the time is 6-12 h.
4. Use of an alkali-modified manganese metal oxide catalyst according to claim 1, characterized in that The reaction time required for the catalytic oxidation of 5-hydroxymethylfurfural to generate the target product is 0.5-12 h.