Zirconium-based tungstic polyacids, their preparation methods, and their applications in the catalytic oxidation of aniline.
By preparing a zirconium-based tungsten polyacid catalyst for the aniline oxidation process, the problems of increased cost and insufficient selectivity of noble metal catalysts were solved, achieving highly efficient selective oxidation of aniline to azobenzene oxide, reducing costs and improving selectivity.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2024-08-12
- Publication Date
- 2026-03-10
AI Technical Summary
The use of precious metal catalysts in existing aniline oxidation processes increases costs and complexity, and the selectivity is low, making it difficult to efficiently oxidize aniline into high-value-added chemicals.
Using a zirconium-based tungsten polyacid catalyst, zirconium-based tungsten polyacid is synthesized in a sodium acetate-acetic acid buffer solution. Combined with hydrogen peroxide, it catalyzes the oxidation of aniline under specific temperature and time conditions to form highly selective azobenzene oxide.
A 98.8% selectivity for aniline to azobenzene oxide was achieved without the use of precious metal catalysts, reducing costs and improving catalyst specificity.
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Abstract
Description
TECHNICAL FIELD
[0001] The present application belongs to the technical field of functional crystalline materials, and particularly relates to a zirconium-based tungsten polyacid, a preparation method thereof and application of the zirconium-based tungsten polyacid in catalyzing oxidation of aniline. BACKGROUND
[0002] Catalysis plays a very important role in the national economy, and has created huge economic and social benefits in the industries of oil refining, chemical industry, environmental protection, pharmaceuticals, energy, and materials. Aniline is one of the most important amine substances. It is mainly used for manufacturing dyes, drugs, resins, and can also be used as a rubber vulcanization accelerator, etc. However, there are often a large amount of aniline in industrial wastewater of these industries, and improper treatment of aniline can cause serious environmental problems. Selective oxidation of aniline by using catalytic oxidation technology into high-value-added chemicals such as azobenzene, azoxybenzene and nitroso benzene meets the demand of green and sustainable development. At present, aniline oxidation is mainly carried out by using Au / TiO2, Au / CeO2, RuO2 / Cu2O, Ag / C-KOH, Au1Pd1@Cx-KOH, Zr(OH)4, etc. However, the additional input of noble metal catalysts and alkaline additives undoubtedly increases the cost and complexity of the catalytic reaction. SUMMARY
[0003] Therefore, the present application aims to provide a zirconium-based tungsten polyacid, a preparation method thereof and application of the zirconium-based tungsten polyacid in catalyzing oxidation of aniline. The catalyst replaces the noble metal catalyst in the current aniline oxidation process, and aniline is oxidized into azoxybenzene with a selectivity of 98.8%.
[0004] A first aspect of the present application provides a zirconium-based tungsten polyacid, and a structural formula of the zirconium-based tungsten polyacid is [(CH3)4N]3K[(PW9O 32 )2(Zr3O3)]·45H2O, crystallographic data and structure parameters are as follows: α = 90°, β = 90°, γ = 120°.
[0005] A second aspect of the present application provides a preparation method of the above-mentioned zirconium-based tungsten polyacid, and the preparation method is as follows: dissolving a polyacid precursor in a sodium acetate-acetic acid buffer solution, stirring until completely dissolved, adding zirconium oxychloride tetrahydrate, tetramethylammonium chloride, potassium chloride, and sodium carbonate, stirring to obtain a mixed solution, reacting at a constant temperature of 150-180°C for 10-16h, cooling to room temperature, filtering, generating crystals in the precipitate, repeatedly washing the crystals with the obtained filtrate, and finally obtaining pure colorless crystals, i.e. the zirconium-based tungsten polyacid; the polyacid precursor is Na9[PW9O 34 ]·7H2O.
[0006] Further, the pH of the sodium acetate-acetic acid buffer solution is 4-5.
[0007] Further, the amount ratio of the polyacid precursor, sodium acetate-acetic acid buffer solution, zirconium oxychloride tetrahydrate, tetramethylammonium chloride, potassium chloride and sodium carbonate is (1-3) g: 10 mL: (1-3) g: (1-3) g: (1-3) g: (1-3) g.
[0008] In a third aspect, the application provides a use of the zirconium-based tungstic acid or the zirconium-based tungstic acid prepared by the above method in catalyzing oxidation of aniline.
[0009] Further, the method for catalyzing oxidation of aniline specifically comprises adding the zirconium-based tungstic acid and hydrogen peroxide into a solution containing aniline, and reacting for 10-20 h under a temperature condition of 30-100 ℃.
[0010] In a fourth aspect, the application provides an aniline oxidation catalyst, which comprises hydrogen peroxide and a zirconium-based tungstic acid, and the zirconium-based tungstic acid is the above zirconium-based tungstic acid or the zirconium-based tungstic acid prepared by the above method.
[0011] Further, in the aniline oxidation catalyst, the concentration of the hydrogen peroxide is 30 wt%, and the amount ratio of the hydrogen peroxide and the zirconium-based tungstic acid is 0.61 mL: (0.028-0.065) g.
[0012] In a fifth aspect, the application further provides an industrial wastewater treatment method, and the industrial wastewater contains aniline.
[0013] Further, the industrial wastewater treatment method specifically comprises adding the zirconium-based tungstic acid and hydrogen peroxide into the industrial wastewater, and reacting for 10-20 h under a temperature condition of 30-100 ℃.
[0014] Further, the industrial wastewater treatment method specifically comprises adding the zirconium-based tungstic acid and hydrogen peroxide into the industrial wastewater, and reacting for 14 h under a temperature condition of 80 ℃.
[0015] Further, the concentration of the hydrogen peroxide is 30 wt%, and the amount ratio of the hydrogen peroxide and the zirconium-based tungstic acid is 0.61 mL: (0.028-0.065) g.
[0016] Further, the concentration of the hydrogen peroxide is 30 wt%, and the amount ratio of the hydrogen peroxide and the zirconium-based tungstic acid is 0.61 mL: 0.037 g.
[0017] Compared with the prior art, the application has the following beneficial effects:
[0018] First, the catalytic reaction does not need to add noble metal catalyst, the cost is reduced; second, the selectivity of 98.8% of the compound is high, and the catalyst has high selectivity. BRIEF DESCRIPTION OF DRAWINGS
[0019] These and / or other aspects and advantages of the present application will become apparent and be more readily understood from the following description, taken in conjunction with the accompanying drawings, in which:
[0020] Figure 1 The infrared spectrum of the compound prepared in Example 1 of the present application is shown in the following figure:
[0021] Figure 2 The anion structure diagram of the compound prepared in Example 1 of the present application is shown in the following figure:
[0022] Figure 3 The results of the catalytic oxidation of aniline by the crystal obtained in Example 1 under different reaction times, different temperatures and different catalyst amounts are shown in the following table:
[0023] Figure 4 The results of the catalytic oxidation of aniline by the crystal obtained in Example 1 under different reaction times, different temperatures and different catalyst amounts are shown in the following table:
[0024] Figure 5 The infrared spectrum of the compound prepared in Example 1 of the present application is shown in the following figure: DETAILED DESCRIPTION
[0025] The present application will be further described in detail below with reference to the examples and drawings, but the embodiments of the present application are not limited thereto. In the examples, the specific conditions not mentioned are carried out according to the conventional conditions or the conditions recommended by the manufacturer. The reagents or instruments used are not marked with the manufacturer, which are all conventional products that can be purchased on the market.
[0026] In the following examples, hydrogen peroxide is commercially available 30wt% hydrogen peroxide.
[0027] Example 1
[0028] (1) Prepare a 0.1mol / L sodium acetate-acetic acid buffer solution with pH=4.
[0029] (2) Weigh 0.5g of polyacid precursor Na9[PW9O 34 ]·7H2O into 10mL of the above buffer solution, and stir until completely dissolved
[0030] (3) Add 0.13g of zirconium oxychloride tetrahydrate, 0.15g of tetramethylammonium chloride, 0.15g of potassium chloride, and 0.11g of ammonium chloride into the above solution in turn, and stir for 1h.
[0031] (4) Put the above mixture into a polytetrafluoroethylene container, add a shell, and put it into an oven, set the temperature to 180℃, and keep it for 12h.
[0032] (5) After the solution is cooled to room temperature, it is filtered, repeatedly washed with the filtrate, and finally colorless crystals are obtained with a yield of 25% (based on Na9[PW9O 34 ]·7H2O).
[0033] Example 2
[0034] (1) A 0.1 mol / L sodium acetate-acetic acid buffer solution with pH = 4.5 is prepared.
[0035] (2) 0.13 g of polyacid precursor Na9[PW9O 34 ]·7H2O is dissolved in 10 mL of the above buffer solution and stirred until completely dissolved.
[0036] (3) 0.13 g of zirconium oxychloride tetrahydrate, 0.15 g of tetramethylammonium chloride, 0.15 g of potassium chloride, and 0.11 g of ammonium chloride are sequentially added to the above solution and stirred for 1 h.
[0037] (4) The above mixture is placed in a polytetrafluoroethylene container, an outer shell is added, and it is placed in an oven with a temperature setting of 180°C for 12 h.
[0038] (5) After the solution is cooled to room temperature, it is filtered, repeatedly washed with the filtrate, and finally colorless crystals are obtained with a yield of 45% (based on Na9[PW9O 34 ]·7H2O).
[0039] Example 3
[0040] (1) A 0.1 mol / L sodium acetate-acetic acid buffer solution with pH = 5 is prepared.
[0041] (2) 0.13 g of polyacid precursor Na9[PW9O 34 ]·7H2O is dissolved in 10 mL of the above buffer solution and stirred until completely dissolved.
[0042] (3) 0.13 g of zirconium oxychloride tetrahydrate, 0.15 g of tetramethylammonium chloride, 0.15 g of potassium chloride, and 0.11 g of ammonium chloride are sequentially added to the above solution and stirred for 1 h.
[0043] (4) The above mixture is placed in a polytetrafluoroethylene container, an outer shell is added, and it is placed in an oven with a temperature setting of 180°C for 12 h.
[0044] (5) After the solution is cooled to room temperature, it is filtered, repeatedly washed with the filtrate, and finally colorless crystals are obtained with a yield of 30% (based on Na9[PW9O 34 ]·7H2O)
[0045] Test Example 1
[0046] The single crystal was selected from the crystal prepared in Example 1, Example 2 and Example 3 for structure determination, and the single crystal was tested and all diffraction data were collected at 296 K by Bruker APEX-II CCD and at 150 K by Bruker D8 VENTURE PHOTON II single crystal diffractometer, and the radiation source was Mo Kα ray of graphite monochromator The hydrogen atom coordinates on the water molecule were obtained by difference Fourier synthesis method, and the coordinates of all non-hydrogen atoms were obtained by direct method, and were optimized by anisotropic thermal parameter correction and matrix least square method, and the hydrogen atoms were directly added to the molecular formula.
[0047] Crystallographic data and structure parameters are shown in Table 1.
[0048] Table 1
[0049]
[0050] The crystal data obtained in Example 1-3 are the same, indicating that they are the same substance, but the yields of the three methods are different.
[0051] Test Example 2
[0052] The crystal obtained in Example 1 was tested by infrared spectrum, and the results are shown in Figure 1 The peak at 964 cm -1 belongs to W=O stretching vibration, and the peaks at 525 cm -1 , 698 cm -1 , 708 cm -1 , 770 cm -1 , 892 cm -1 belong to W-O-W stretching vibration, and the peaks at 1025 cm -1 , 1086 cm -1 are caused by P-O stretching vibration, and the peak at 3463 cm -1 belongs to O-H stretching vibration. The structure of the obtained compound is:
[0053] [(CH3)4N]3K[(PW9O 32 )2(Zr3O3)]·45H2O, and the structure diagram of the obtained compound is shown in Figure 2 .
[0054] Test Example 3
[0055] The catalytic oxidation performance of the compound was studied with aniline as substrate, hydrogen peroxide as oxidant and water as solvent.
[0056] The compound was added into a parallel reactor with 0.18 mL aniline, 6 mL water, 0.61 mL hydrogen peroxide and 0.037 g compound, and the catalytic oxidation performance of the compound on aniline was studied at different temperatures and different reaction times. Based on the UV spectrum of the oil solution after the reaction, the effects of the catalytic temperature and time on the amount of the catalytic product were investigated. With the increase of the temperature (from room temperature to 80 °C), the peak intensity of the solution at 310 nm gradually increased, and the peak intensity was the largest at 80 °C. At 80 °C, with the extension of the reaction time, the intensity also gradually increased, and therefore, it can be considered that the catalytic reaction was the most thorough at 80 °C for 14 h. Figure 3 a).
[0057] After the optimal time and temperature were determined, the amount of the catalyst was changed to 0.028 g, 0.037 g, 0.047 g, 0.056 g and 0.065 g. The lower red oil drops were dissolved in methanol, and the liquid UV of each sample was tested by diluting at a constant ratio as shown in Figure 3 b. The results show that the best catalytic effect is obtained when the amount of the catalyst is 0.037 g.
[0058] Under the optimal conditions, the oil after the catalytic reaction was extracted with 5 mL methanol, and was tested in a gas chromatograph-mass spectrometer. The concentration of the product was 39.1 g / L, and the main oxidation product was azoxybenzene ( Figure 4 ), and there was a small amount of nitrobenzene. The selectivity of aniline oxidation to azoxybenzene was 98.8%.
[0059] In order to compare the effects of hydrogen peroxide and the catalyst on the reaction system, two groups of comparative experiments were set. Under the optimal temperature and time conditions, when no hydrogen peroxide was added, there was almost no red oil drop in the obtained product, indicating that the reaction basically did not occur. When no catalyst was added under the same conditions, there was a small amount of red oil drop in the obtained product, and the azoxybenzene content was 25.2 g / L by gas chromatograph-mass spectrometer detection. The conversion rate of aniline oxidation to azoxybenzene was 63.5%. The results show that the catalyst has excellent catalytic effect on the selective oxidation of aniline to azoxybenzene.
[0060] In order to verify the stability of the compound in the catalytic process, the compound after catalysis was tested by infrared spectrum as shown in Figure 5 . The infrared spectra of the compound before and after catalysis were almost the same, indicating that the structure of the catalyst did not change in the catalytic process.
[0061] The above examples are the preferred embodiments of the present application, but the embodiments of the present application are not limited by the above examples, and any changes, modifications, substitutions, combinations, simplifications made without departing from the spirit and principles of the present application shall be equivalent replacement modes, and all shall be included in the protection scope of the present application.
Claims
1. A zirconium-based tungstic acid characterized in that, The structural formula of the zirconium-based tungsten polyacid is [(CH3)4N]3K[(PW9O 32 )2(Zr3O3)]·45H2O, and the crystallographic data and structure parameters are a = 22.8508 Å, b = 22.8508 Å, c = 39.6484 Å, α = 90°, β = 90°, γ = 120°, V = 17929.145 Å 3 .
2. A method of preparing the zirconium-based tungstic acid of claim 1, characterized in that, The preparation method is as follows: dissolving a polyacid precursor in a sodium acetate-acetic acid buffer solution, stirring until completely dissolved, adding zirconium oxychloride tetrahydrate, tetramethylammonium chloride, potassium chloride and sodium carbonate, stirring to obtain a mixed solution, reacting at a constant temperature of 150-180 DEG C for 10-16 h, cooling to room temperature, filtering, repeatedly washing the crystals in the precipitate with the obtained filtrate, and finally obtaining pure colorless crystals, namely the zirconium-based tungsten polyacid; the polyacid precursor is Na9[PW9O 34 ]·7H2O.
3. The production method according to claim 2, characterized by, The pH of the sodium acetate-acetic acid buffer solution is 4-5.
4. The production method according to claim 3, characterized by, The ratio of the use amount of the polyacid precursor, the sodium acetate-acetic acid buffer solution, the zirconium oxychloride tetrahydrate, the tetramethylammonium chloride, the potassium chloride and the sodium carbonate is (1-3) g: 10 mL: (1-3) g: (1-3) g: (1-3) g: (1-3) g.
5. The use of the zirconium-based tungsten polyacid in the catalysis of aniline oxidation.
6. Use according to claim 5, characterized in that, The method for catalyzing aniline oxidation specifically comprises adding the zirconium-based tungsten polyacid and hydrogen peroxide into a solution containing aniline, and reacting for 10-20 h under the temperature condition of 30-100 ℃.
7. Aniline oxidation catalyst characterized in that, The aniline oxidation catalyst comprises hydrogen peroxide and the zirconium-based tungsten polyacid, and the zirconium-based tungsten polyacid is the zirconium-based tungsten polyacid as claimed in claim 1.
8. The amine oxidation catalyst according to claim 7, characterized in that In the aniline oxidation catalyst, the concentration of the hydrogen peroxide is 30 wt%, and the ratio of the use amount of the hydrogen peroxide to the zirconium-based tungsten polyacid is 0.61 mL: (0.028-0.065) g.
9. An industrial wastewater treatment method, said industrial wastewater containing aniline, characterized by, The industrial wastewater treatment method specifically comprises: adding the zirconium-based tungsten polyacid as claimed in claim 1 and hydrogen peroxide into industrial wastewater, and reacting for 10-20 h under the temperature condition of 30-100 ℃.
10. The industrial wastewater treatment method according to claim 9, characterized by, The concentration of the hydrogen peroxide is 30 wt%, and the ratio of the use amount of the hydrogen peroxide to the zirconium-based tungsten polyacid is 0.61 mL: (0.028-0.065) g.