W-RuO2 nano-catalyst as well as preparation method and application thereof

Abstract

The invention discloses a W-RuO2 nano-catalyst and a preparation method and application thereof.The preparation method of the W-RuO2 nano-catalyst comprises the steps that ruthenium trichloride and phosphotungstic acid are added into deionized water to be stirred, a solution A is obtained, and the mass ratio of the ruthenium trichloride to the phosphotungstic acid is 0.5-13; heating the solution A, then dropwise adding an ammonia water solution, stirring to obtain a precursor solution B, and centrifuging, washing and drying the precursor solution B to obtain a W-RuO2 precursor; the W-RuO2 precursor is subjected to calcination, and the W-RuO2 nano catalyst is obtained; the calcining temperature is 350 to 550 DEG C; the W-RuO2 nano-catalyst prepared by the preparation method is high in activity, selectivity and stability, and is beneficial to improving the synthesis efficiency of electrically driven ethylene glycol.

Description

Technical Field

[0001] This invention belongs to the field of electrocatalysis technology, specifically relating to a W-RuO2 nanocatalyst, its preparation method, and its application. Background Technology

[0002] Ethylene glycol, a key basic chemical, is a core raw material supporting modern industrial systems and is widely used in critical areas such as polyester resins, automotive antifreeze, natural gas dehydrating agents, and electronic electrolytes. Industry data shows that global ethylene glycol production exceeded 230 million tons in 2023, with China being the largest producer, accounting for 60% of global capacity. Northeast Asia contributed nearly 78% of the total capacity, and global annual production continues to grow steadily at a rate of 4-5%. In traditional industrial production, ethylene glycol is produced using a classic two-step thermocatalytic process: first, using a silver-based catalyst, ethylene is oxidized to ethylene oxide at 200-300℃ in an oxygen atmosphere of 1-3 MPa; then, the hydration and ring-opening reaction of ethylene oxide is completed under strong acid conditions. This process not only has stringent reaction conditions and energy consumption as high as 22.6 GJ / ton, but also involves significant carbon emissions—an average of 1.6 tons of carbon dioxide are emitted for every ton of ethylene glycol produced.

[0003] In contrast, electrochemically driven ethylene conversion to ethylene glycol exhibits significant advantages. This process can operate at ambient temperature and pressure and can utilize renewable energy for power generation, providing a new technological pathway for achieving green and sustainable ethylene glycol production. In recent years, researchers have made some progress in improving the efficiency of electrochemically driven ethylene glycol synthesis by designing efficient catalysts and optimizing reaction pathways. Nevertheless, the practical application of this technology still faces multiple challenges: the extremely low solubility of ethylene in aqueous electrolytes limits the mass transfer rate; simultaneously, anodic competing reactions (such as the oxygen evolution reaction) and side reactions such as excessive oxidation of ethylene to CO2 result in an overall current density generally below 20 mA / cm². -2 Furthermore, the Faraday efficiency is also difficult to exceed the 80% industrial feasibility threshold. In addition, the structural stability of catalysts and the maintenance of active sites in complex reaction environments remain current research challenges.

[0004] Patent application CN117753411A discloses a relatively simple synthesis method for obtaining transition metal-doped RuO2 uniformly loaded onto CNTs. In this application, the introduction of carbon nanotubes effectively limits the particle size of the transition metal-doped RuO2 catalyst, increasing the active surface area. Furthermore, carbon nanotubes can provide a faster electron transport rate, further improving the catalytic performance. The catalysts obtained in this application exhibit oxygen evolution reaction overpotentials above 280 mV in 0.5 M H2SO4, with the lowest reaching 210 mV, significantly lower than the 300 mV of commercial RuO2. However, the introduction of excessive substances in the catalyst preparation disclosed in this patent application can easily introduce impurities, affecting the catalyst's performance.

[0005] Patent application CN120797035A discloses a method for preparing Ru-WO3 nanocatalysts, their products, and applications. The method for preparing the Ru-WO3 nanocatalyst includes: adding ammonium metatungstate to deionized water and stirring to obtain solution A; then adding citric acid to solution A to obtain solution B; and mixing solution B with titanium felt and subjecting it to a hydrothermal reaction to obtain WO3. 3-x Carrier; to carry WO 3-x The carrier is impregnated with an aqueous solution of RuCl3 to obtain Ru-WO 3-x Precursor; Ru-WO 3-x The precursor was calcined to obtain Ru-WO3 nanocatalysts; the mass ratio of ammonium metatungstate to citric acid was 2.4-10. The Ru-WO3 nanocatalysts prepared by this method exhibit high activity and selectivity, which is beneficial for improving the efficiency of electro-driven ethylene glycol synthesis. However, the stability of the Ru-WO3 nanocatalysts disclosed in this patent application needs further improvement. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention provides a method for preparing W-RuO2 nanocatalysts. The W-RuO2 nanocatalysts prepared by this method exhibit high activity, selectivity, and stability, which is beneficial for improving the efficiency of electro-driven ethylene glycol synthesis.

[0007] This invention provides a method for preparing W-RuO2 nanocatalysts, comprising: (1) Add ruthenium trichloride and phosphotungstic acid to deionized water and stir to obtain solution A, wherein the mass ratio of ruthenium trichloride to phosphotungstic acid is 0.5-13; (2) Heat the solution A, then add ammonia solution dropwise and stir to obtain precursor solution B. Centrifuge, wash and dry the precursor solution B to obtain W-RuO2 precursor; (3) The W-RuO2 precursor is calcined to obtain W-RuO2 nanocatalyst; the calcination temperature is 350-550℃.

[0008] This invention creates an alkaline environment by adding ammonia water, so that the precursor solution B after the reaction contains hydroxide ions, which, combined with the subsequent calcination process, can form tungsten-doped ruthenium dioxide.

[0009] If the temperature is too low, the tungstate or ruthenium hydroxide on the catalyst surface cannot be completely decomposed, thus forming an amorphous mixture of ruthenium oxide and tungsten oxide, which reduces the conductivity of the material and the activity of the catalyst. If the temperature is too high, Ostwald ripening will occur, the grains will grow rapidly, the specific surface area will decrease sharply, resulting in a sharp reduction in the number of active sites. At the same time, W will segregate out to form a mixed phase, losing the synergistic effect of doping.

[0010] Preferably, the calcination holding time is 2-4 hours.

[0011] Preferably, in step (2), the heating temperature is 60-90°C.

[0012] Preferably, the concentration of the ammonia solution is 0.1-2 mol / L, and the reaction time is 5 min-2 h.

[0013] This invention, by controlling the concentration and reaction time of the ammonia solution, enables the ammonia solution to react with phosphotungstic acid to form tungstate ions that are adsorbed on the surface of ruthenium hydroxide, thus preparing for subsequent calcination to form tungsten-doped ruthenium oxide.

[0014] On the other hand, the present invention also provides a W-RuO2 nanocatalyst, which is prepared by the method described above.

[0015] Compared with the existing RuO2 catalyst, which undergoes oxygen evolution and other side reactions during electrolysis in the electro-driven ethylene glycol synthesis reaction, making it difficult to generate active Br species and significantly reducing catalytic efficiency, the W-RuO2 nanocatalyst provided in this invention is more likely to generate active Br species during electrolysis, reducing the occurrence of oxygen evolution side reactions and thus improving the ethylene glycol Faradaic efficiency. Therefore, compared with the existing RuO2 catalyst, the W-RuO2 nanocatalyst provided in this invention has higher catalytic performance.

[0016] Preferably, in the W-RuO2 nanocatalyst, Ru, W, and O elements are uniformly distributed, wherein the mass percentages of Ru, W, and O elements are 45.4-59.8%, 9.1-36.4%, and 18.2-34.6%, respectively.

[0017] This invention ensures that the active sites on the catalyst can participate in the reaction uniformly and fully by controlling the mass ratio and distribution of Ru, W and O elements, which is beneficial to improving the efficiency and selectivity of the reaction.

[0018] On the other hand, the present invention also provides the application of the W-RuO2 nanocatalyst in the electro-driven ethylene glycol synthesis reaction, including: In the alkaline electrolyte system, the alkaline electrolyte is a mixture of potassium bromide and potassium hydroxide. The W-RuO2 nanocatalyst is used as the anode, and ethylene gas is continuously introduced. The ethylene is converted into ethylene glycol through an electrically driven reaction mediated by bromide species.

[0019] This invention utilizes the aforementioned W-RuO2 nanocatalyst for electro-driven ethylene glycol synthesis. Due to the doping of W, the W-RuO2 nanocatalyst can efficiently catalyze the Br2 reaction. - In-situ oxidation to generate BrO - Due to the alkaline environment, BrO - A stable existence, thus enabling the utilization of BrO - Ethylene glycol is synthesized by direct oxidation of ethylene.

[0020] Preferably, the molar ratio of potassium bromide to potassium hydroxide is 10-60.

[0021] Preferably, the concentration of potassium hydroxide is one of 0.01 mol / L, 0.05 mol / L, and 0.1 mol / L, and the concentration of potassium bromide is one of 1 mol / L and 3 mol / L. The concentration of potassium hydroxide is 0.05-0.1 mol / L, and the concentration of potassium bromide is 1-3 mol / L.

[0022] More preferably, the concentration of potassium hydroxide is 0.05 mol / L and the concentration of potassium bromide is 3 mol / L. At this combined concentration, the catalytic effect reaches a good level, enabling the Faraday efficiency of ethylene glycol electrosynthesis to reach 86.4% and the current density to reach 50 mA cm⁻¹. -2 .

[0023] Preferably, the flow rate of the ethylene gas is 30-100 mL / min.

[0024] Preferably, the counter electrode for the electrocatalytic reaction is a C rod, the reference electrode is Hg / HgO, and the applied current is 10 mA / cm². -2 Up to 100mA cm -2 The anode products were detected by proton nuclear magnetic resonance spectroscopy. In this embodiment of the invention, by controlling the current density, a Faradaic efficiency of over 50% for ethylene glycol was achieved, indicating that the W-RuO2 nanocatalyst has a stable and good effect on the electro-driven ethylene glycol synthesis reaction.

[0025] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention, by controlling the mass ratio of ruthenium trichloride and phosphotungstic acid, enables sufficient W to be doped into RuO2, thereby facilitating the formation of active Br species during electrolysis, reducing oxygen evolution side reactions, and improving the ethylene glycol Faradaic efficiency. Simultaneously, it avoids excessive W dissolution affecting active sites and catalytic performance. This invention also ensures uniform tungstate doping by inducing tungstate adsorption on the ruthenium hydroxide surface with ammonia. Furthermore, the tungsten incorporated into the crystal lattice elongates the Ru-O bonds, reducing the covalent nature of Ru and preventing its oxidation to higher valence states, thus ensuring catalyst stability. Attached Figure Description

[0026] Figure 1 X-ray diffraction patterns of the W-RuO2 and RuO2 catalysts prepared in Examples 1 to 4 and Comparative Examples 1 and 2 of this invention; Figure 2 The Raman spectra of the W-RuO2 and RuO2 catalysts prepared in Example 1 and Comparative Example 1 of this invention are shown below. Figure 3 Scanning and transmission electron microscopy images of the W-RuO2 catalyst prepared in Example 1 of this invention; Figure 4 In application examples 1, 2, 3, 4 and comparative examples 1, 2 provided for this invention, the 50 mA cm -2 The Faraday efficiency of W-RuO2 electrode for catalytic oxidation of ethylene at current densities; Figure 5 In application example 1 provided by the present invention, 10-100mA cm -2 The Faraday efficiency of electrocatalytic oxidation of ethylene at current density; Figure 6 The Faraday efficiency diagrams of ethylene oxidation catalyzed by the W-RuO2 electrode in application examples 1, 5, 6, and 7 provided for this invention; Figure 7 The following are examples of the application of this invention: using W-RuO2 as the electrode, the ultraviolet spectra of the electrolyte after electrolysis without ethylene flow and the ultraviolet spectra of the electrolyte after electrolysis with ethylene flow. Figure 8 In Application Example 1 provided by the present invention, W-RuO2 is used as the electrode, and the product is subjected to 1H NMR spectrum after electrolysis and ethylene is passed through the electrode. Figure 9 This is a cyclic voltammetric scan of W-RuO2 and RuO2 prepared in Example 1 and Comparative Example 1 as electrodes. Figure 10 The galvanostatic curves and Faraday efficiency diagrams of W-RuO2 electrodes calcined at different temperatures provided in Comparative Example 2 of this invention are shown below. Figure 10 (a) is the electrode constant current curve. Figure 10 (b) is the Faraday efficiency diagram; Figure 11 The Faraday efficiency diagram and scanning electron microscope images of the catalyst before and after cyclic electrolysis are shown in Application Example 1 provided by the present invention, using W-RuO2 as the electrode. Figure 11 (a) shows the current-voltage curves and Faraday efficiency plot for 10 cycles of electrolysis. Figure 11 (b) is a scanning electron microscope image of the catalyst before and after cyclic electrolysis. Detailed Implementation

[0027] Example 1 The preparation method of the W-RuO2 nanocatalyst provided in this embodiment is as follows: 0.13 g of ruthenium chloride and 0.072 g of phosphotungstic acid were weighed and dissolved in 50 mL of deionized water, and stirred until homogeneous to obtain solution A. Solution A was heated to 75 °C and maintained for 5 min, followed by the dropwise addition of 0.75 mL of ammonia water. The reaction was allowed to proceed for 5 min. After the reaction, the solution was washed and dried by centrifugation with deionized water and ethanol to obtain the W-RuO2 precursor. The W-RuO2 precursor was calcined in a muffle furnace at 450 °C for 2 h to obtain the catalyst W-RuO2.

[0028] X-ray diffraction analysis was performed on the W-RuO2 prepared in Example 1 ( Figure 1 The presence of characteristic diffraction peaks of RuO2 was found, which can be indexed as standard PDF card (43-1027). No W-related diffraction peaks were found in the spectrum, and the characteristic diffraction peak at 28.1° showed a negative shift, indicating that W entered the RuO2 bulk phase in the form of doping.

[0029] Raman spectroscopy analysis was performed on the W-RuO2 prepared in Example 1. Figure 2 Three distinct Ru-O vibrational peaks (E) were observed. g A 1g B 2g Furthermore, compared to RuO2, there is a significant red shift, indicating that W doping generates glacial stress, elongating the spatial distance between Ru-O bonds, consistent with XRD results. Additionally, B... 2g The weakening of the peak indicates that W occupies the octahedral Ru position.

[0030] Scanning electron microscopy analysis of the W-RuO2 prepared in Example 1 revealed that W-RuO2 exhibits a particle structure with a size of 50-100 nm. Figure 3 Elemental analysis showed that Ru, W, and O were uniformly distributed, with Ru, W, and O accounting for 52.4%, 18.2%, and 29.4% of the total mass, respectively.

[0031] Example 2 The only difference from Example 1 is that 0.018 g of phosphotungstic acid was added in Example 2 to obtain catalyst 7.2W-RuO2.

[0032] X-ray diffraction analysis of the 7.2W-RuO2 prepared in Example 2 revealed the presence of characteristic diffraction peaks of RuO2 and the absence of W-related diffraction peaks, indicating that W enters the RuO2 bulk phase in the form of doping.

[0033] Example 3 The only difference from Example 1 is that 0.036 g of phosphotungstic acid was added in Example 3 to obtain catalyst 3.6W-RuO2.

[0034] X-ray diffraction analysis of the 3.6W-RuO2 prepared in Example 3 revealed the presence of characteristic diffraction peaks of RuO2 and the absence of W-related diffraction peaks, indicating that W enters the RuO2 bulk phase in the form of doping.

[0035] Example 4 The only difference from Example 1 is that 0.144 g of phosphotungstic acid was added in Example 4 to obtain catalyst 0.9W-RuO2.

[0036] X-ray diffraction analysis of the 0.9W-RuO2 prepared in Example 4 revealed the presence of characteristic diffraction peaks of RuO2 and the absence of W-related diffraction peaks, indicating that W enters the RuO2 bulk phase in the form of doping.

[0037] Application Example 1 The W-RuO2 prepared in Example 1 was used as the electrocatalyst for ethylene oxidation to construct a three-electrode system for electrochemical testing. The anode electrode was W-RuO2, the cathode electrode was a carbon rod, and the reference electrode was Hg / HgO, placed at the anode. The anode electrolyte consisted of 25 ml of a potassium hydroxide solution containing 3 mol / L potassium bromide (potassium hydroxide concentration 0.05 mol / L). The cathode electrolyte composition was the same as the anode electrolyte. During electrolysis, ethylene was continuously introduced into the anode at a gas flow rate of 60 mL / min.

[0038] Testing different current densities (10 mA cm⁻¹) -2 -100mA cm -2 The Faraday efficiency of W-RuO2 catalytic oxidation of ethylene to ethylene glycol is as follows: Figure 5 This indicates that the catalyst W-RuO2 at 10 mA cm⁻¹ -2 -100mA cm -2 It exhibits a Faradaic efficiency exceeding 50% for ethylene glycol production across the entire current density range, with byproducts primarily being ethylene oxide, formic acid, and bromoethanol. When an applied current density of 50 mA / cm² is applied... -2 At that time, the Faraday efficiency for producing ethylene glycol can reach 86.4%.

[0039] When ethylene is not supplied during electrolysis, 50mA cm -2 Ultraviolet spectra of the electrolyte after W-RuO2 electrolysis with and without ethylene passage, such as... Figure 7 As shown, without ethylene, W-RuO2 electrolysis produces BrO. - In oxide species, the characteristic UV-Vis peak is located at 327 nm. However, after electrolysis and the introduction of ethylene, this characteristic peak disappears, indicating that BrO... - The oxide species reacts chemically with ethylene.

[0040] Test 50mA cm -2 The proton NMR spectrum of the products obtained by electrolysis of W-RuO2 at a given current density followed by ethylene passage. Figure 8 This indicates that at 50mA cm -2 Electrolysis at a certain current density followed by the passage of ethylene produces ethylene glycol, indicating that the reaction pathway is W-RuO2 catalyzed Br. - Oxidized to BrO - Species, then BrO - The species oxidizes ethylene to ethylene glycol, and the built-in NMR calibrator provided by this invention is dimethyl sulfoxide.

[0041] Test the cyclic voltammetry curve of W-RuO2. Figure 9 The large difference in the area of ​​the reduction peaks indicates that the Br species oxidized on the surface of the catalyst W-RuO2 are quickly consumed by ethylene, converting ethylene into ethylene glycol.

[0042] Testing the cyclic electrolysis performance of W-RuO2, Figure 11 (a) indicates that the voltage remained stable and the Faraday efficiency remained at around 81% during 10 electrolysis cycles; Figure 11 (b) revealed that the catalyst morphology did not change significantly before and after cyclic electrolysis, indicating that the catalyst has good stability.

[0043] Application Example 2 The only difference from Application Example 1 is that Application Example 2 uses the 7.2W-RuO2 prepared in Example 2 as the ethylene oxidation electrocatalyst.

[0044] Test 50mA cm -2 The Faradaic efficiency of ethylene oxidation to ethylene glycol catalyzed by 7.2 W-RuO2 at a current density. Figure 4 This indicates that 7.2W-RuO2, as an electrocatalyst for ethylene oxidation, exhibits a good ethylene glycol Faradaic efficiency of 67.8%.

[0045] Application Example 3 The only difference from Application Example 1 is that Application Example 3 uses the 3.6W-RuO2 prepared in Example 3 as the ethylene oxidation electrocatalyst.

[0046] Test 50mA cm -2 The Faradaic efficiency of ethylene oxidation to ethylene glycol catalyzed by 3.6W-RuO2 at a current density. Figure 4 This indicates that 3.6W-RuO2, as an electrocatalyst for ethylene oxidation, exhibits a good ethylene glycol Faradaic efficiency of 81.3%.

[0047] Application Example 4 The only difference from Application Example 1 is that Application Example 4 uses the 0.9W-RuO2 prepared in Example 4 as the ethylene oxidation electrocatalyst.

[0048] Test 50mA cm -2 The Faradaic efficiency of ethylene oxidation to ethylene glycol catalyzed by 0.9 W-RuO2 at a current density. Figure 4 This indicates that 0.9W-RuO2, as an electrocatalyst for ethylene oxidation, exhibits a good ethylene glycol Faradaic efficiency of 68.2%.

[0049] The combined application of Examples 1, 2, 3, and 4 shows that a good synthesis effect of ethylene glycol is achieved within the mass ratio of ruthenium chloride to phosphotungstic acid in the range of 0.9-7.2.

[0050] Application Example 5 The only difference from Application Example 1 is that the electrolyte in Application Example 5 is a 25 ml potassium hydroxide solution containing 1 mol / L potassium bromide, with a potassium hydroxide concentration of 0.05 mol / L.

[0051] Test 50mA cm -2 The Faraday efficiency of W-RuO2-catalyzed ethylene oxidation to ethylene glycol at current density Figure 6 This indicates that the electrolyte combination exhibits a good ethylene glycol Faraday efficiency of 62.5%.

[0052] Application Example 6 The only difference from Application Example 1 is that the electrolyte in Application Example 6 is a 25 ml potassium hydroxide solution containing 1 mol / L potassium bromide, with a potassium hydroxide concentration of 0.1 mol / L.

[0053] Test 50mA cm -2 The Faraday efficiency of W-RuO2-catalyzed ethylene oxidation to ethylene glycol at current density Figure 6 This indicates that the electrolyte combination exhibits a good ethylene glycol Faraday efficiency of 68.1%.

[0054] Application Example 7 The only difference from Application Example 1 is that the electrolyte in Application Example 7 is a 25 ml potassium hydroxide solution containing 3 mol / L potassium bromide, with a potassium hydroxide concentration of 0.1 mol / L.

[0055] Test 50mA cm -2 The Faraday efficiency of W-RuO2-catalyzed ethylene oxidation to ethylene glycol at current density Figure 6 This indicates that the electrolyte combination exhibits a good ethylene glycol Faraday efficiency of 69.5%.

[0056] Based on the above application examples, there exists an optimal ratio of potassium bromide to potassium hydroxide concentrations that results in a high ethylene glycol Faradaic efficiency, with the ratio ranging from 10 to 60. The highest ethylene glycol Faradaic efficiency, reaching 86.4%, is achieved when the potassium hydroxide concentration is 0.05 mol / L and the potassium bromide concentration is 3 mol / L.

[0057] Comparative Example 1 The difference from Example 1 is that phosphotungstic acid is not added, resulting in the catalyst RuO2.

[0058] X-ray diffraction analysis of the catalyst RuO2 ( Figure 1 The presence of characteristic diffraction peaks for RuO2 was observed, indicating the successful preparation of the pure-phase RuO2 catalyst. Raman spectroscopy analysis of RuO2 was also performed. Figure 2 A significant Ru-O signal peak was found in RuO2.

[0059] The only difference from Application Example 1 is that Comparative Example 1 uses RuO2 catalyst as the electrocatalyst for ethylene oxidation.

[0060] Test 50mA cm -2 The performance of RuO2 in catalyzing the oxidation of ethylene at the specified current density showed a Faraday efficiency of 13.7%. Figure 4 ).

[0061] Test the cyclic voltammetry curve of RuO2. Figure 9 The smaller difference in the reduction peak area indicates that there are fewer active Br species on the surface of the catalyst RuO2 compared to W-RuO2, and therefore it cannot convert ethylene to ethylene glycol.

[0062] Comparative Example 2 The only difference from Example 1 is that 0.288 g of phosphotungstic acid was added to Comparative Example 2 to obtain catalyst 0.4W-RuO2.

[0063] X-ray diffraction analysis of the 0.4W-RuO2 prepared in Comparative Example 2 revealed the presence of characteristic diffraction peaks of RuO2 and the absence of W-related diffraction peaks, indicating that W enters the RuO2 bulk phase in the form of doping.

[0064] Comparative Example 2 uses a 0.4W-RuO2 electrode as an electrocatalyst for ethylene oxidation.

[0065] Test 50mA cm -2The performance of the 0.4W-RuO2 electrode in catalyzing the oxidation of ethylene at a current density of 50 mA cm⁻¹. -2 The Faraday efficiency for the catalytic oxidation of ethylene to ethylene glycol at the specified current density is relatively low, at 46.1%. Figure 4 ).

[0066] The results of Comparative Examples 1 and 2 show that the W component in the W-RuO2 nanocatalyst can synergistically interact with Ru within a certain doping ratio range to promote the efficient electrosynthesis of ethylene glycol.

[0067] Comparative Example 3 Compared to Example 1, the calcination temperature of W-RuO2 was 650°C.

[0068] Comparative Example 3 uses a W-RuO2-650 electrode calcined at 650℃ as an electrocatalyst for ethylene oxidation.

[0069] Test 50mA cm -2 Current galvanostatic curves of W-RuO2 electrodes calcined at different temperatures under different current densities ( Figure 10 a) It was found that the voltage was lowest at a calcination temperature of 450℃ and highest at 650℃. This is because both lower and higher calcination temperatures are unfavorable for W doping, leading to the formation of a WO3 miscible phase and reducing the catalyst's conductivity. Furthermore, higher calcination temperatures also cause severe catalyst sintering, reducing the density of active sites and decreasing catalytic activity.

[0070] Test 50mA cm -2 The performance of the W-RuO2-650 electrode in catalytic ethylene oxidation at current density of 50 mA cm⁻¹ -2 The Faraday efficiency for the catalytic oxidation of ethylene to ethylene glycol at current density is low, only 6% ( Figure 10 (b) The performance of the catalyst is significantly lower than that of the catalyst calcined at 350-550℃.

[0071] The results of Comparative Example 3 show that the W-RuO2 nanocatalyst promotes the formation of the W-RuO2 active phase in the calcination temperature range of 350-550℃, thereby promoting the high-efficiency electrosynthesis of ethylene glycol.

Claims

1. A method for preparing a W-RuO2 nanocatalyst, characterized in that, include: (1) Add ruthenium trichloride and phosphotungstic acid to deionized water and stir to obtain solution A, wherein the mass ratio of ruthenium trichloride to phosphotungstic acid is 0.5-13; (2) Heat the solution A, then add ammonia solution dropwise and stir to obtain precursor solution B. Centrifuge, wash and dry the precursor solution B to obtain W-RuO2 precursor; (3) The W-RuO2 precursor is calcined to obtain W-RuO2 nanocatalyst, wherein the calcination temperature is 350-550℃.

2. The method for preparing W-RuO2 nanocatalyst according to claim 1, characterized in that, The calcination holding time is 2-4 hours.

3. The method for preparing W-RuO2 nanocatalyst according to claim 1, characterized in that, In step (2), the heating temperature is 60-90℃.

4. The method for preparing W-RuO2 nanocatalyst according to claim 1, characterized in that, The concentration of the ammonia solution is 0.1-2 mol / L, and the reaction time is 5 min-2 h.

5. A W-RuO2 nanocatalyst according to any one of claims 1-4, characterized in that, The W-RuO2 nanocatalyst was prepared using the method described above.

6. The W-RuO2 nanocatalyst according to claim 5, characterized in that, In the W-RuO2 nanocatalyst, Ru, W, and O elements are uniformly distributed, with the mass percentages of Ru, W, and O elements being 45.4-59.8%, 9.1-36.4%, and 18.2-34.6%, respectively.

7. An application of the W-RuO2 nanocatalyst according to claim 5 or 6 in an electro-driven ethylene glycol synthesis reaction, characterized in that, include: In the alkaline electrolyte system, the alkaline electrolyte is a mixture of potassium bromide and potassium hydroxide. The W-RuO2 nanocatalyst is used as the anode, and ethylene gas is continuously introduced. The ethylene is converted into ethylene glycol through an electrically driven reaction mediated by bromide species.

8. The application of the W-RuO2 nanocatalyst according to claim 7 in the electro-driven ethylene glycol synthesis reaction, characterized in that, The molar ratio of potassium bromide to potassium hydroxide is 10-60.

9. The application of the W-RuO2 nanocatalyst according to claim 7 in the electro-driven ethylene glycol synthesis reaction, characterized in that, The flow rate of the ethylene gas is 30-100 mL / min.

10. The application of the W-RuO2 nanocatalyst according to claim 7 in the electro-driven ethylene glycol synthesis reaction, characterized in that, The counter electrode for the electrocatalytic reaction is a C rod, the reference electrode is Hg / HgO, and the applied current is 10 mA cm⁻¹. -2 Up to 100mA cm -2 The anode products were detected by proton nuclear magnetic resonance spectroscopy.

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