A montmorillonite-supported ruthenium oxide catalyst, its preparation method and application

Abstract

This invention relates to the field of catalyst technology, and more particularly to a montmorillonite-supported ruthenium oxide catalyst, its preparation method, and its application. The preparation method of the montmorillonite-supported ruthenium oxide catalyst of this invention includes the following steps: S1, calcining montmorillonite to obtain modified montmorillonite; S2, growing a ruthenium oxide precursor on the modified montmorillonite using a water bath method; S3, calcining the montmorillonite-supported ruthenium oxide precursor. In this invention, the modified montmorillonite obtained after calcination has a large number of adsorption active sites, which can effectively anchor noble metals and enhance catalytic activity. The modified montmorillonite forms chemical bonds with RuO2 at the interface, causing tensile stress in the RuO2 crystals, which alleviates the excessive oxidation of oxygen atoms in RuO2 during the oxygen evolution reaction (OER), maintaining the high activity of the catalyst; furthermore, RuO2 can maintain high OER activity at a relatively low loading, significantly reducing costs.

Description

Technical Field

[0001] This invention relates to the field of catalyst technology, and in particular to a montmorillonite-supported ruthenium oxide catalyst, its preparation method, and its application. Background Technology

[0002] Proton exchange membrane electrolysis (PEMWE) for hydrogen production offers rapid response to external power input, making it suitable for coupling with renewable energy sources. However, the kinetics of the oxygen evolution reaction (OER) at the anolyte of PEMWE are slow, severely impacting energy conversion efficiency. Furthermore, most materials fail to function properly in the acidic environment and at high potentials of PEMWE. Ruthenium oxide (RuO2) possesses high intrinsic OER catalytic activity, but it is expensive, often requiring high loadings of this precious metal in practical applications, significantly increasing material costs. Therefore, designing low-loading, highly active RuO2-based electrocatalysts is crucial for advancing PEMWE hydrogen production technology and its large-scale commercial application. Summary of the Invention

[0003] The purpose of this invention is to address the aforementioned shortcomings of the prior art by proposing a montmorillonite-supported ruthenium oxide catalyst, its preparation method, and its application.

[0004] The present invention provides a method for preparing a montmorillonite-supported ruthenium oxide catalyst, comprising the following steps:

[0005] S1. Calcine montmorillonite to obtain modified montmorillonite;

[0006] S2. Ruthenium oxide precursor is grown on modified montmorillonite by water bath method;

[0007] S3. The montmorillonite-supported ruthenium oxide precursor was calcined to obtain the final product, montmorillonite-supported ruthenium oxide catalyst.

[0008] Furthermore, in step S1, calcination is carried out at 500–800℃ for 1–6 hours.

[0009] Further, the specific operation of step S2 is as follows: the modified montmorillonite is dispersed in an aqueous solution of ruthenium chloride, heated and stirred in a water bath at 70-95°C until the water evaporates, and then ground evenly to obtain a montmorillonite-supported ruthenium oxide precursor.

[0010] Furthermore, the mass ratio of modified montmorillonite to ruthenium chloride is 4:7–16.

[0011] Furthermore, in step S3, calcination is carried out at 400–500℃ for 2–4 hours.

[0012] Furthermore, in step S3, the sample is calcined at 480°C for 3 hours.

[0013] A montmorillonite-supported ruthenium oxide catalyst prepared by the method described above.

[0014] An application of the montmorillonite-supported ruthenium oxide catalyst described above, used as a catalyst for the oxygen evolution reaction.

[0015] In this invention, the modified montmorillonite obtained after calcination has a large number of adsorption active sites, which can effectively anchor noble metals and enhance catalytic activity. Modified montmorillonite forms chemical bonds with RuO2 at the interface, causing tensile stress in the RuO2 crystals, which alleviates the excessive oxidation of oxygen atoms in RuO2 during the oxygen evolution reaction (OER) and maintains the high activity of the catalyst. Furthermore, RuO2 can maintain high OER activity at a relatively low loading, significantly reducing costs.

[0016] The montmorillonite-supported RuO2 catalyst prepared by this invention exhibits high activity at 10 mA cm⁻¹. -2 It exhibits an overpotential as low as 200mV at the OER current density. Attached Figure Description

[0017] Figure 1 X-ray powder diffraction patterns of pure montmorillonite and modified montmorillonite;

[0018] Figure 2a and Figure 2b Solid-state NMR spectra of Al and Si in montmorillonite and modified montmorillonite;

[0019] Figure 3 X-ray powder diffraction patterns of montmorillonite, montmorillonite-supported ruthenium oxide, and pure ruthenium oxide;

[0020] Figure 4 Raman spectra of montmorillonite, montmorillonite-supported ruthenium oxide, and pure ruthenium oxide;

[0021] Figure 5 Catalytic activity diagrams of montmorillonite, montmorillonite-supported ruthenium oxide, and pure ruthenium oxide;

[0022] Figure 6 Mass activity diagrams of montmorillonite, montmorillonite-supported ruthenium oxide, and pure ruthenium oxide. Detailed Implementation

[0023] The following are specific embodiments of the present invention, which are described in conjunction with the accompanying drawings. However, the present invention is not limited to these embodiments.

[0024] Example 1

[0025] The preparation of the montmorillonite-supported ruthenium oxide catalyst was carried out according to the following steps:

[0026] Step 1

[0027] Take 5g of montmorillonite, grind it, put the montmorillonite into a crucible, calcine it in a muffle furnace at 700℃ for 4 hours, cool it to room temperature, and then grind it to obtain modified montmorillonite.

[0028] Step Two

[0029] 40 mg of modified montmorillonite and 122.4 mg of ruthenium chloride were dispersed in 15 ml of deionized water, and dried by heating and stirring in a water bath at 90 °C. The mixture was then ground to obtain montmorillonite-supported ruthenium chloride.

[0030] Step 3

[0031] Ruthenium chloride supported on montmorillonite was placed in a crucible and calcined in a muffle furnace at 480°C for 3 hours to obtain ruthenium oxide supported on montmorillonite.

[0032] Example 2

[0033] The difference between this embodiment and Example 1 is that the calcination time in step one is 5 hours, while the other steps are the same as in Example 1.

[0034] Example 3

[0035] The difference between this embodiment and Example 1 is that the calcination time in step one is 3 hours, while the other steps are the same as in Example 1.

[0036] Example 4

[0037] The difference between this embodiment and Example 1 is that the calcination time in step one is 2 hours, while the other steps are the same as in Example 1.

[0038] Example 5

[0039] The difference between this embodiment and Example 1 is that the calcination temperature in step one is 800℃, while the other steps are the same as in Example 1.

[0040] Example 6

[0041] The difference between this embodiment and Example 1 is that the calcination temperature in step one is 600℃, while the other steps are the same as in Example 1.

[0042] Example 7

[0043] The difference between this embodiment and Example 1 is that the calcination temperature in step one is 500℃, while the other steps are the same as in Example 1.

[0044] Example 8

[0045] The difference between this embodiment and Example 1 is that the mass of ruthenium chloride in step two is 78.64 mg, while the other steps are the same as in Example 1.

[0046] Example 9

[0047] The difference between this embodiment and Example 1 is that the mass of ruthenium chloride in step two is 160 mg, while the other steps are the same as in Example 1.

[0048] Example 10

[0049] The difference between this embodiment and Example 1 is that the calcination temperature in step three is 400°C. All other steps are the same as in Example 1.

[0050] Example 11

[0051] The difference between this embodiment and Example 1 is that the calcination temperature in step three is 450°C. All other steps are the same as in Example 1.

[0052] Example 12

[0053] The difference between this embodiment and Example 1 is that the calcination temperature in step three is 500°C. All other steps are the same as in Example 1.

[0054] Example 13

[0055] The difference between this embodiment and Example 1 is that the calcination time in step three is 2 hours. All other steps are the same as in Example 1.

[0056] Application Examples

[0057] For the oxygen evolution reaction test, 4 mg of the montmorillonite-supported ruthenium oxide catalyst prepared in Example 1 was added to a mixed solution of 200 μl isopropanol, 32 μl 5 wt.% Nafion, and 768 μl deionized water. After ultrasonic dispersion for 1 h, a uniform slurry was obtained. 7 μl of the slurry was dropped onto the surface of a glassy carbon electrode with a diameter of 5 mm. After the slurry was dried, a loading of 0.14 mg / cm³ was obtained. 2 The working electrode was a carbon rod as the counter electrode, an Ag / AgCl electrode as the reference electrode, and a 0.5M sulfuric acid solution as the electrolyte. A rotating disk motor was used, with the working electrode rotating at 1600 rpm and a scan rate of 10 mV / s to obtain the linear polarization curve of the oxygen evolution reaction. In this embodiment, the montmorillonite-supported ruthenium oxide electrocatalyst was used at 10 mA cm⁻¹. -2 The overpotential at the operating current density is 200mV, such as Figure 5 As shown.

[0058] Figure 1 These are the XRD patterns of pure montmorillonite and modified montmorillonite. Comparing the peaks of montmorillonite after loading, it can be seen that the (001) peak shifts to the right, indicating that the interlayer spacing of montmorillonite has decreased and interlayer water has been released.

[0059] Figure 2a and Figure 2bThese are solid-state NMR spectra of Al and Si in montmorillonite and modified montmorillonite, showing the results of Al calcination. VI Peak weakens, Al IV The peaks become stronger and broader. This indicates that the number of octahedral coordinated aluminum atoms decreases while the number of tetrahedral coordinated aluminum atoms increases.

[0060] Figure 3 These are the XRD patterns of montmorillonite, montmorillonite-supported ruthenium oxide, and pure ruthenium oxide. It can be seen that RuO2 is well supported on montmorillonite.

[0061] Figure 4 These are Raman spectra of montmorillonite, montmorillonite-supported ruthenium oxide, and pure ruthenium oxide. The figures show the Bt of calcined montmorillonite-supported ruthenium oxide. 2g A 1g E g The decrease in wavenumbers indicates a reduction in the vibrational frequency of the Ru-O bond and an increase in bond length. Combined with the XRD results, it can be concluded that the calcined montmorillonite loaded with ruthenium oxide exhibits tensile stress between the crystal lattices, which has a positive impact on catalytic activity.

[0062] Figure 5 These are LSV plots of montmorillonite, montmorillonite-supported ruthenium oxide, and pure ruthenium oxide. The plots show that after calcination of montmorillonite-supported ruthenium oxide, the LSV at 10 mA cm⁻¹... -2 The overpotential at the operating current density is 200mV because the coordination structure of montmorillonite changes after calcination, with six-coordinated aluminum transforming into four-coordinated aluminum, generating a large number of active sites that anchor ruthenium oxide on the support, thereby improving catalytic activity.

[0063] Figure 6 The graphs show the mass activity of montmorillonite, montmorillonite-supported ruthenium oxide, and pure ruthenium oxide. After calcination, the mass activity of montmorillonite-supported ruthenium oxide is significantly better than that of alcohol-supported ruthenium oxide and montmorillonite-supported ruthenium oxide.

[0064] For any points not covered above, existing technologies shall apply.

[0065] Although specific embodiments of the present invention have been described in detail by way of examples, those skilled in the art should understand that the above examples are for illustrative purposes only and are not intended to limit the scope of the invention. Those skilled in the art can make various modifications or additions to the described specific embodiments or use similar methods to replace them, without departing from the direction of the invention or exceeding the scope defined by the appended claims. Those skilled in the art should understand that any modifications, equivalent substitutions, improvements, etc., made to the above embodiments based on the technical essence of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a montmorillonite-supported ruthenium oxide catalyst, characterized in that: Includes the following steps: S1. Calcine montmorillonite to obtain modified montmorillonite; S2. Ruthenium oxide precursor is grown on modified montmorillonite by water bath method; S3. The montmorillonite-supported ruthenium oxide precursor was calcined to obtain the final product, montmorillonite-supported ruthenium oxide catalyst. In step S1, calcination is carried out at 500~800℃ for 1~6 hours; The mass ratio of modified montmorillonite to ruthenium chloride is 4:7~16.

2. The preparation method according to claim 1, characterized in that: The specific operation of step S2 is as follows: the modified montmorillonite is dispersed in an aqueous solution of ruthenium chloride, heated and stirred in a water bath at 70~95℃ until the water evaporates, and then ground evenly to obtain the montmorillonite-supported ruthenium oxide precursor.

3. The preparation method according to claim 1, characterized in that: In step S3, calcination is carried out at 400~500℃ for 2~4 hours.

4. The preparation method according to claim 1, characterized in that: In step S3, calcination is carried out at 480℃ for 3 hours.

5. A montmorillonite-supported ruthenium oxide catalyst prepared by the preparation method according to any one of claims 1-4.

6. The application of the montmorillonite-supported ruthenium oxide catalyst as described in claim 5, characterized in that: Used as a catalyst for the oxygen evolution reaction.

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