Montmorillonite-loaded ruthenium oxide catalyst as well as preparation method and application thereof

Abstract

The invention relates to the technical field of catalysts, in particular to a montmorillonite-loaded ruthenium oxide catalyst as well as a preparation method and application thereof. The preparation method of the montmorillonite-loaded ruthenium oxide catalyst comprises the following steps: S1, calcining montmorillonite to obtain modified montmorillonite; s2, growing a ruthenium oxide precursor on the modified montmorillonite through a water bath method; and S3, carrying out calcination treatment on the montmorillonite-loaded ruthenium oxide precursor. According to the preparation method, the modified montmorillonite obtained after calcination has more adsorption active sites, precious metal can be anchored well, and the catalytic activity is improved. The modified montmorillonite and RuO2 form chemical bonding on an interface, so that RuO2 crystals have tensile stress, the excessive oxidation of oxygen atoms in the RuO2 in the oxygen evolution reaction process is relieved, and the high activity of the catalyst is kept; and the RuO2 can maintain high OER activity under the condition of low loading capacity, so that the cost is remarkably reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of catalysts, and in particular to a montmorillonite-supported ruthenium oxide catalyst and a preparation method and application thereof. Background Art

[0002] Proton exchange membrane water electrolysis (PEMWE) hydrogen production technology can respond quickly to external power input and is suitable for coupling with renewable energy to produce hydrogen. However, the kinetics of the anode oxygen evolution reaction (OER) of PEMWE is relatively slow, which seriously affects the energy conversion efficiency; at the same time, most materials cannot work properly under the acidic working environment and high potential of PEMWE. Ruthenium oxide (RuO2) has high intrinsic catalytic activity for OER, but it is expensive. In practical applications, high loadings of precious metals are often used, which significantly increases the material cost. Therefore, designing low-loading and highly active RuO2-based electrocatalysts is the key to promoting the development of PEMWE hydrogen production technology and its large-scale commercial application. Summary of the invention

[0003] The purpose of the present invention is to address the above-mentioned deficiencies in the prior art and to provide a montmorillonite-supported ruthenium oxide catalyst and a preparation method and application thereof.

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

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

[0006] S2, growing a ruthenium oxide precursor on modified montmorillonite by a water bath method;

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

[0008] Furthermore, in step S1, calcination is performed at 500-800° C. for 1-6 hours.

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

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

[0011] Furthermore, in step S3, calcination is performed at 400-500° C. for 2-4 hours.

[0012] Furthermore, in step S3, calcination is performed at 480° C. for 3 h.

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

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

[0015] In the present invention, the modified montmorillonite obtained after calcination has more adsorption active sites, which can well anchor precious metals and improve catalytic activity. The modified montmorillonite forms a chemical bond with RuO2 at the interface, causing the RuO2 crystal to have tensile stress, alleviating the over-oxidation of oxygen atoms in RuO2 during the oxygen evolution reaction, and maintaining the high activity of the catalyst; and RuO2 can maintain a high OER activity at a lower loading, significantly reducing costs.

[0016] The montmorillonite-supported RuO2 catalyst prepared by the present invention has high activity at 10 mA cm -2 The OER current density is as low as 200 mV with an overpotential. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0018] Figure 2a and Figure 2b Solid-state NMR images 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-loaded ruthenium oxide, and pure ruthenium oxide;

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

[0022] Figure 6 Mass activity diagram of montmorillonite, montmorillonite-supported ruthenium oxide, and pure ruthenium oxide. DETAILED DESCRIPTION

[0023] The following are specific embodiments of the present invention and the accompanying drawings to further describe the technical solution of the present invention, but the present invention is not limited to these embodiments.

[0024] Example 1

[0025] The preparation of montmorillonite-supported ruthenium oxide catalyst is completed according to the following steps:

[0026] Step 1:

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

[0028] Step 2:

[0029] 40 mg of modified montmorillonite and 122.4 mg of ruthenium chloride were dispersed in 15 ml of deionized water, heated, stirred, dried and ground at 90° C. in a water bath to obtain montmorillonite-loaded ruthenium chloride.

[0030] Step 3:

[0031] Montmorillonite-loaded ruthenium chloride was placed in a crucible and calcined in a muffle furnace at 480° C. for 3 h to obtain montmorillonite-loaded ruthenium oxide.

[0032] Example 2

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

[0034] Example 3

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

[0036] Example 4

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

[0038] Example 5

[0039] The difference between this embodiment and Example 1 is that the calcination temperature in step 1 is 800° C., and the other steps are consistent with Example 1.

[0040] Example 6

[0041] The difference between this embodiment and Example 1 is that the calcination temperature in step 1 is 600° C., and the other steps are consistent with Example 1.

[0042] Example 7

[0043] The difference between this embodiment and Example 1 is that the calcination temperature in step 1 is 500° C., and the other steps are consistent with Example 1.

[0044] Example 8

[0045] The difference between this embodiment and Example 1 is that the mass of ruthenium chloride in step 2 is 78.64 mg, and the other steps are consistent with Example 1.

[0046] Example 9

[0047] The present embodiment is different from Example 1 in that the mass of ruthenium chloride in step 2 is 160 mg, and the other steps are consistent with Example 1.

[0048] Example 10

[0049] The difference between this embodiment and Example 1 is that the calcination temperature in step 3 is 400° C. The other steps are consistent with Example 1.

[0050] Embodiment 11

[0051] The difference between this embodiment and Example 1 is that the calcination temperature in step 3 is 450° C. The other steps are consistent with Example 1.

[0052] Example 12

[0053] The difference between this embodiment and Example 1 is that the calcination temperature in step 3 is 500° C. The other steps are consistent with Example 1.

[0054] Embodiment 13

[0055] The present embodiment is different from Example 1 in that the calcination time in step 3 is 2 hours. The other steps are the same as those in Example 1.

[0056] Application Examples

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

[0058] Figure 1 The XRD patterns of pure montmorillonite and modified montmorillonite are shown in Figure 2. 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 decreases and interlayer water escapes.

[0059] Figure 2a and Figure 2bThis is the solid NMR image of Al and Si in montmorillonite and modified montmorillonite. It is concluded that Al VI The peak weakens, Al IV The peaks become stronger and broader, which indicates that the number of aluminum atoms with octahedral coordination decreases and the number of aluminum atoms with tetrahedral coordination increases.

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

[0061] Figure 4 This is the Raman spectra of montmorillonite, montmorillonite-loaded ruthenium oxide, and pure ruthenium oxide. The figure shows that the B 2g , A 1g , E g , the wave number decreases, indicating that the vibration frequency of the Ru-O bond decreases and the bond length lengthens. Combined with the results of XRD, it is concluded that the calcined montmorillonite-loaded ruthenium oxide has tensile stress between the lattices, which has a positive effect on the catalytic activity.

[0062] Figure 5 The LSV diagrams of montmorillonite, montmorillonite-supported ruthenium oxide, and pure ruthenium oxide show that after calcining montmorillonite-supported ruthenium oxide, the -2 The overpotential at the working current density is 200mV because the coordination structure of montmorillonite changes after calcination, and the hexacoordinated aluminum is converted into tetracoordinated aluminum, generating a large number of active sites, anchoring ruthenium oxide on the carrier and improving the catalytic activity.

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

[0064] For matters not mentioned above, the prior art applies.

[0065] Although some specific embodiments of the present invention have been described in detail through examples, those skilled in the art should understand that the above examples are for illustration only and are not intended to limit the scope of the present invention. Those skilled in the art to which the present invention belongs may make various modifications or supplements to the specific embodiments described or replace them in a similar manner, but they will not deviate from the direction of the present invention or exceed the scope defined by the attached 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 in the protection scope of the present invention.

Claims

1. A method for preparing a montmorillonite-supported ruthenium oxide catalyst, characterized in that: The steps include: S1. calcining montmorillonite to obtain modified montmorillonite; S2, growing a ruthenium oxide precursor on modified montmorillonite by a water bath method; S3. calcining the montmorillonite-supported ruthenium oxide precursor to obtain the final product, montmorillonite-supported ruthenium oxide catalyst.

2. The preparation method according to claim 1, characterized in that: In step S1, calcination is performed at 500-800° C. for 1-6 hours.

3. 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 a ruthenium chloride aqueous solution, heated and stirred at 70 to 95° C. in a water bath until the water is evaporated, and then ground evenly to obtain a montmorillonite-loaded ruthenium oxide precursor.

4. The preparation method according to claim 3, characterized in that: The mass ratio of modified montmorillonite to ruthenium chloride is 4:7-16.

5. The preparation method according to claim 1, characterized in that: In step S3, calcination is performed at 400-500° C. for 2-4 hours.

6. The preparation method according to claim 1, characterized in that: In step S3, calcination is performed at 480° C. for 3 h.

7. A montmorillonite-supported ruthenium oxide catalyst prepared by the preparation method according to any one of claims 1 to 6.

8. Use of the montmorillonite-supported ruthenium oxide catalyst as claimed in claim 7, characterized in that: Used as a catalyst for oxygen evolution reaction.

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