A method for in-situ desolventizing plasma and stabilizing metal oxide surface nanoparticles

Abstract

The application discloses a method for in-situ desolubilization and stabilization of metal oxide surface nanoparticles by plasma, comprising the following steps: preparing a metal nano-catalyst by using a metal oxide precursor and a nanoparticle precursor; pre-treating the metal nano-catalyst by plasma discharge in a hydrogen gas, oxygen gas or mixed gas atmosphere composed of hydrogen gas and inert gas; in-situ desolubilizing the nanoparticles in the metal oxide of the metal nano-catalyst by plasma discharge in a reducing atmosphere; and stabilizing the interface between the metal nanoparticles and the metal oxide by plasma discharge in an oxidizing or inert gas atmosphere. The application in-situ processes the catalyst under different atmosphere conditions, and utilizes the plasma to process the catalyst under different stages and different atmospheres, so that the activity and stability of the obtained catalyst are improved. The application improves the conventional plasma method, and is convenient to operate, simple in process and short in process.

Description

Technical Field

[0001] This invention relates to the field of plasma surface engineering technology, specifically to a method for in-situ plasma desolvation and stabilization of nanoparticles on the surface of metal oxides. Background Technology

[0002] Nanocatalysts possess excellent catalytic performance and play a crucial role in industrial catalysis processes in fields such as environment and energy. Typically, for metal nanocatalysts, reduction treatment is a common and effective method to enhance the activity of metal nanoparticles and thus the catalyst. Research has found that the interaction between metal nanoparticles and the support has a significant impact on catalytic performance: it can control particle size and modulate the carrier effect between them. The stability of metal nanoparticles on the metal oxide surface is key to obtaining highly active and stable nanocatalysts.

[0003] Currently, the most common method for preparing nanocatalysts is the hydrothermal reduction method. For example, treating catalysts under a reducing atmosphere to obtain supported metal catalysts can alter the structure of the metal nanoparticles and precursors. When some metal nanoparticles are supported on the catalyst surface, the catalyst activity is improved. However, this method, while regulating the interaction between the metal and precursor, also changes the size of the active particles. Furthermore, this method requires prolonged treatment under a reducing atmosphere, resulting in high energy consumption and a long cycle time. Additionally, the reduced nanoparticles easily return to the metal oxide lattice, leading to catalyst instability. To improve the catalytic activity of nanocatalysts, plasma technology has received widespread attention in catalyst preparation. Using plasma to prepare nanocatalysts, due to its non-equilibrium characteristics (low temperature, high activity), plasma-treated catalysts typically yield smaller metal particles, thus improving activity. Treating catalysts in a reducing atmosphere disperses metal nanoparticles on the catalyst surface, but conventional plasma treatment struggles to obtain uniformly dispersed and highly stable metal nanoparticles. The reduced metal nanoparticles are unevenly dispersed and unstable on the surface, resulting in poor stability and reduced activity of the catalyst during long-term use. Summary of the Invention

[0004] This invention addresses the aforementioned problems by researching and designing a method for in-situ plasma desolvation and stabilization of nanoparticles on the surface of metal oxides. The technical means employed in this invention are as follows:

[0005] A method for in-situ plasma desolvation and stabilization of nanoparticles on the surface of metal oxides includes the following steps:

[0006] S1: Metal nanocatalysts were prepared using metal oxide precursors and nanoparticle precursors;

[0007] S2: Pretreatment of metal nanocatalysts is performed using plasma discharge in an atmosphere of hydrogen, oxygen, or a mixture of hydrogen and inert gas.

[0008] S3: In a reducing atmosphere, plasma discharge is used to perform in-situ desolvation treatment on the nanoparticles in the metal oxide of the metal nanocatalyst.

[0009] S4: In an oxidizing or inert gas atmosphere, plasma discharge is used to stabilize the interface between metal nanoparticles and metal oxides.

[0010] Furthermore, the metal precursor is a soluble metal salt or a soluble metal oxide, and the nanoparticle precursor is a soluble metal salt or a soluble metal oxide.

[0011] Furthermore, the nanoparticle precursor is a soluble salt of a rare metal, a soluble oxide of a rare metal, a soluble salt of a noble metal, or a soluble oxide of a noble metal, and the metal oxide precursor is one or a mixture of two or more of lanthanum nitrate, cobalt nitrate, iron nitrate, manganese nitrate, and cerium oxide.

[0012] Further, in step S1, a mixed solution of metal precursor and nanoparticle precursor is prepared, and metal nanocatalyst is obtained by combustion, calcination and drying using self-propagating combustion method, sol-gel method or template method. The pH value of both the metal precursor solution and the nanoparticle precursor solution is less than 7.

[0013] Furthermore, steps S2-S4 are performed in a plasma generator, which generates plasma through dielectric barrier discharge or corona discharge, and the discharge processing time in each step is 10-30 minutes.

[0014] Furthermore, the power supply for dielectric barrier discharge is an AC power supply or a pulse power supply, and the power supply for corona discharge is a DC power supply or a pulse power supply. The frequency of the AC power supply is 2-20kHz, and the applied voltage is 5-10kV. The applied voltage of the DC power supply is 2-12kV. The pulse width of the pulse power supply is less than 1000ns. The instantaneous discharge power of the AC power supply and the DC power supply is greater than 10W, and the instantaneous discharge power of the pulse power supply is greater than 6kW.

[0015] Furthermore, in steps S2-S4, the inert gas is one or a mixture of helium and argon, and both the reducing and oxidizing atmospheres are under continuous gas flow conditions with a space velocity of 2000-400000 h⁻¹. -1 .

[0016] Further, step S2 is carried out in a mixed gas atmosphere, wherein the mixed gas is a mixture of reducing gas and inert gas; step S3 is carried out in a mixed gas atmosphere, wherein the mixed gas is a mixture of reducing gas and inert gas; step S4 is carried out in a mixed gas atmosphere, wherein the mixed gas is a mixture of oxidizing gas and inert gas.

[0017] Furthermore, in step S2, the volume percentage of hydrogen in the mixed gas is not less than 10%; in step S3, the volume percentage of hydrogen in the mixed gas is not less than 20%; and in step S4, the volume percentage of oxygen in the mixed gas is greater than 10%.

[0018] Compared with existing technologies, the method for in-situ plasma desolvation and stabilization of nanoparticles on the surface of metal oxides described in this invention has the following advantages:

[0019] 1. This invention prepares a catalyst by thoroughly mixing a nanoparticle precursor with a metal oxide precursor solution. The catalyst is initially phased by calcination or combustion, and then metal nanoparticles are obtained by in-situ desolvation through plasma treatment. The preparation process is simple, convenient, and the prepared catalyst has high reproducibility. The surface distribution of the metal nanoparticles is uniform and the dispersion is high.

[0020] 2. This invention utilizes plasma under a reducing atmosphere to pretreat the catalyst, thereby altering the surface structure of the metal oxide and increasing the concentration of defect sites. Then, plasma under a reducing atmosphere is used to activate the catalyst, and finally, plasma under an oxidizing atmosphere is used to stabilize the nanoparticles on the surface. This pretreatment can significantly enhance the oxygen vacancies and coordination unsaturation at the interface between the nanoparticles and the metal oxide, altering the stability of some metal oxide structures, which is beneficial for improving the catalytic activity of the catalyst.

[0021] 3. In the final step of this invention, plasma stabilization of nanoparticles and metal oxides is carried out under an oxidizing atmosphere. The oxidizing atmosphere ensures the stability of the valence state of the metal nanoparticles and can also partially oxidize other particles on the surface, generating a carrier effect between the nanoparticles and the metal oxide, as well as the nesting stability of the nanoparticles by the metal oxide. This avoids the phenomenon of nanoparticles migrating on the surface of the metal oxide during the use of the catalyst. This ensures the activity of the catalyst while giving the metal nanoparticles extremely strong stability.

[0022] 4. In this invention, the pretreatment and reduction of nanoparticles in metal oxides by plasma, as well as the regulation of the interaction between nanoparticles and metal oxides, are all achieved by adjusting the discharge time, discharge atmosphere and instantaneous power of the plasma. This adjustment method is highly targeted and flexible, effectively reducing nanoparticle precursors, and has significant advantages in the interaction between nanoparticles and metal oxides, overcoming the instability of conventional plasma treatment methods in reducing nanoparticles.

[0023] 5. This invention uses a combination of undetermined atmosphere plasma to treat the catalyst, which is more efficient and rapid than the traditional method of thermal reduction to regulate the interaction between nanoparticles and metal oxides, and the energy consumption during the treatment process is extremely low.

[0024] 6. This invention uses plasma with different atmospheres to treat catalysts in different processes. The treatment device is inexpensive, easy to assemble and operate, and is suitable for both the preparation of fine chemical catalysts and large-scale production applications. Attached Figure Description

[0025] Figure 1 This is a graph showing the toluene conversion rate in Example 1 of the present invention.

[0026] Figure 2 This is a CO conversion rate graph from Embodiment 2 of the present invention.

[0027] Figure 3 This is a graph showing the acetylene conversion rate in Example 3 of the present invention. Detailed Implementation

[0028] This invention provides a method for in-situ plasma desolvation and stabilization of nanoparticles on the surface of metal oxides. This method is applied to doped metal nanocatalysts, and its operation steps are as follows: S1, prepare a mixed solution of metal precursor and nanoparticle precursor of metal oxide, and obtain well-formed metal oxide by self-propagating combustion, sol-gel method or template method; S2, perform surface pretreatment of metal oxide by plasma discharge; S3, perform in-situ rapid desolvation of nanoparticles in metal oxide by plasma under a reducing atmosphere; S4, treat the desolvated metal oxide by plasma under an oxidizing atmosphere to stabilize the nanoparticle / metal oxide interface.

[0029] In step S1, the combustion, calcination, and drying times and temperatures of the catalysts obtained by the combustion method, sol-gel method, and template method are determined by the specific components. For the combustion method, attention should be paid to the combustion time to ensure complete combustion of the precursor. For the sol-gel method, attention should be paid to the drying time and temperature. A vacuum drying oven should be selected as much as possible during drying. For the template method, attention should be paid to ensuring that the thickness of the template is consistent in order to obtain a catalyst with a uniform structure.

[0030] In steps S2-S4, the plasma generator produces plasma through dielectric barrier discharge or corona discharge. The discharge processing time in each step is between 10-30 minutes, with the specific time varying. Specifically, the plasma generator can be a dielectric barrier discharge or corona discharge reactor, with the catalyst placed at the center of the discharge reactor.

[0031] Preferably, the power supply for dielectric barrier discharge is a pulsed power supply or an AC power supply, and the power supply for corona discharge is a pulsed power supply or a DC power supply. The instantaneous discharge power of the DC or AC power supply is greater than 10W, and the instantaneous discharge power of the pulsed power supply is greater than 6kW. The frequency of the AC power supply is 2-20kHz, and the applied voltage is 5-10kV; the applied voltage of the DC power supply is 2-12kV; and the pulse width of the pulsed power supply is less than 1000ns. The discharge processing time of the pulsed power supply is 10-20 minutes.

[0032] Preferably, in steps S2-S4, the inert gas is one or a mixture of helium and argon, and both the reducing atmosphere and the oxidizing atmosphere are under continuous gas flow conditions with a space velocity of 2000-400000 h⁻¹. -1 .

[0033] Preferably, step S2 is carried out in a mixed gas atmosphere, wherein the mixed gas is a mixture of a reducing gas and an inert gas, preferably a mixture of hydrogen and argon; step S3 is carried out in a mixed gas atmosphere, wherein the mixed gas is a mixture of a reducing gas and an inert gas, preferably a mixture of hydrogen and argon; step S4 is carried out in a mixed gas atmosphere, wherein the mixed gas is a mixture of an oxidizing gas and an inert gas, preferably a mixture of oxygen and argon. In step S2, the volume percentage of hydrogen in the mixed gas is not less than 10%; in step S3, the volume percentage of hydrogen in the mixed gas is not less than 20%; in step S4, the volume percentage of oxygen in the mixed gas is greater than 10%.

[0034] For the preparation of active nanoparticles on the surface of metal oxides, the plasma method yields catalysts with higher activity and stability, and the entire process is simple, rapid, flexible, and energy-efficient. By mixing the precursor of active nanoparticles with the precursor of metal oxides, and then using an in-situ desolvation method to precipitate the active nanoparticles onto the metal oxide surface, the resulting catalyst often exhibits higher activity. Conventional in-situ desolvation methods involve hydrothermal reduction, which requires prolonged treatment of the catalyst under a reducing atmosphere, resulting in high energy consumption, long cycles, and the nanoparticles easily returning to the metal oxide lattice after reduction. Currently, plasma preparation methods are mostly used for catalyst surface treatment, essentially achieving the dispersion of metal nanoparticles on the surface; however, it is difficult to obtain uniformly dispersed and highly stable metal nanoparticles.

[0035] This invention utilizes plasma technology to treat catalysts in situ under different atmospheric conditions, resulting in improved catalyst activity and stability. The conventional plasma method is improved for its ease of operation and simplicity; each catalyst treatment step takes no more than 30 minutes, the process is concise, and the power required for the discharge process is low, resulting in extremely low energy consumption. By treating the catalyst with plasma at different stages and under different atmospheres, the pretreatment stage modulates the catalyst surface structure, creating oxygen vacancies on the surface. The formation of oxygen vacancies inhibits the return of in-situ dissolved metal nanoparticles to the metal oxide lattice. Plasma treatment under a reducing atmosphere yields a large number of uniformly dispersed active nanoparticles on the metal oxide surface. Finally, oxygen plasma treatment stabilizes the interface structure between the metal nanoparticles and the metal oxide surface, embedding some of the dissolved particles within the metal oxide lattice, resulting in excellent activity and stability.

[0036] Example 1:

[0037] A method for in-situ plasma desolvation and stabilization of nanoparticles on the surface of metal oxides includes the following steps:

[0038] a. Weigh 4.3301g of lanthanum nitrate and 2.7356g of cobalt nitrate, dissolve them in 200ml of deionized water, and heat and stir to prepare a 40g / L chloroplatinic acid standard solution (metal nanoparticle precursor standard solution). Measure 6.15ml of chloroplatinic acid and add it to 200ml of deionized water.

[0039] b. Heat the mixture in a water bath at 60 r / min. Weigh out 8.4056 g of citric acid and 5.8448 g of ethylenediaminetetraacetic acid and add them to the above 206.15 mL solution. After the particles are completely dissolved and the water bath temperature reaches 80 °C, measure the pH value of the solution with a pH meter. Then, use a disposable dropper to add ammonia solution dropwise to adjust the pH value of the solution to between 7.00 and 7.50.

[0040] c. After adjusting the pH, seal the beaker with plastic wrap, and then fully complex it in a water bath at 80℃ and 60r / min for 5 hours. After that, lift the film and wait for the water to evaporate to a certain extent, and the solution will become a wet gel.

[0041] d. Place the obtained wet gel sample in a ceramic bowl and burn it on an electric furnace for 30-50 minutes to obtain LaCo. 0.94 Pt 0.06 O3 catalyst particles were then ground into a fine powder using a mortar and pestle, placed in a crucible, and calcined in a muffle furnace at 950°C for 7 hours. The resulting product, LaCo, was then pressed into tablets and sieved. 0.94 Pt 0.06 O3 catalyst;

[0042] e. Pretreatment of LaCo using H2 and Ar dielectric barrier discharge plasma in a dielectric barrier discharge reactor. 0.94 Pt 0.06 The O3 catalyst was used for 5 min, the gas flow rate was 50 mL / min, the volume ratio of H2 to Ar was 1:4, and the power supply for the discharge reactor was a 10 kHz AC power supply with an input power of 20 W.

[0043] f. Reprocessing activated LaCo using H2 and Ar dielectric barrier discharge plasma 0.94 Pt 0.06 O3 catalyst for 20 min, gas flow rate of 50 mL / min, volume ratio of H2 to Ar of 1:5, power supply of 10 kHz AC power supply, input power of 30 W;

[0044] g. Pt / LaCo pretreated material activated by O2 and Ar dielectric barrier discharge plasma. 0.94 Pt y O3 catalyst for 5 min, gas flow rate of 50 mL / min, O2 to Ar volume ratio of 1:2, power supply for the discharge reactor of 10 kHz AC power, input power of 15 W; Pt / LaCo 0.94 Pt y O3 composite nanocatalyst.

[0045] The Pt / LaCo obtained in Example 1 0.94 Pt 0.06 The catalytic oxidation and removal performance of O3 composite nanocatalysts for C7H8 was evaluated under the following conditions: a gas mixture consisting of 50 vol% C7H8, 20 vol% O2, and 30 vol% N2 was subjected to a 100,000 h⁻¹ reaction. -1 airspeed one-way flow through Pt / LaCo 0.94 Pt y O3 catalyst surface. As a comparative study, catalysts subjected to untreated (950℃), H2 reduction treatment, and conventional plasma treatment were also tested and evaluated under the same conditions, and the results are as follows: Figure 1 As shown.

[0046] The results show that the Pt / LaCo treated in this embodiment... 0.94 Pt 0.06 The O3 catalyst exhibited a higher C7H8 conversion rate (96%). Under the same conditions, the catalyst activity after conventional H2 reduction treatment was 72%, the catalyst activity after conventional H2 plasma treatment was 80%, and the untreated catalyst activity was 50%. The plasma-controlled catalyst achieved the highest activity due to the interaction between Pt nanoparticles and LaCo. 0.94 Pt 0.06 The interactions between O3 molecules were effectively regulated. For example... Figure 1 As shown, due to the interaction between metal nanoparticles and LaCo 0.94 Pt 0.06 With suitable interactions between O3, the in-situ reduction of reactant C7H8 in Pt / LaCo under the same conditions... 0.94 Pt 0.06 The surface conversion rate of O3 increased significantly.

[0047] Example 2:

[0048] A method for in-situ plasma desolvation and stabilization of nanoparticles on the surface of metal oxides includes the following steps:

[0049] a. Weigh 13.0266g of cerium nitrate and dissolve it in 40ml of deionized water to prepare a 40g / L chloroauric acid standard solution (metal nanoparticle precursor standard solution). Measure 4.12ml of chloroauric acid and add it to the above mixed solution.

[0050] b. Heat and stir in a water bath, add a certain amount of 25%-28% ammonia solution to the above solution, adjust the pH of the solution to 10, and mix and stir for 4 hours at 100 r / min.

[0051] c. Then transfer the above solution to a large centrifuge tube, cool to room temperature, sonicate for 10 minutes, centrifuge for 10 minutes, discard the supernatant, add deionized water, and repeat the above operation 3 times.

[0052] d. After washing with water, the centrifuge tubes were placed in an oven and dried at 80°C for 6 hours. Then they were placed in a muffle furnace and calcined at 550°C for 4 hours to obtain Au-CeO2 catalyst.

[0053] e. In the dielectric barrier discharge reactor, the Au-CeO2 catalyst was pretreated for 5 min using H2 and Ar dielectric barrier discharge plasma. The gas flow rate was 50 mL / min, the volume ratio of H2 to Ar was 1:4, and the power supply for the discharge reactor was a 15 kHz AC power supply with an input power of 10 W.

[0054] f. The activated Au-CeO2 catalyst was retreated with H2 and Ar dielectric barrier discharge plasma for 20 min. The gas flow rate was 60 mL / min, the volume ratio of H2 to Ar was 1:5, the power supply was a 15 kHz AC power supply, and the input power was 15 W.

[0055] g. The pretreated Au / CeO2 catalyst was activated for 5 min using O2 and Ar dielectric barrier discharge plasma, with a gas flow rate of 80 mL / min, a volume ratio of O2 to Ar of 1:2, and the power supply for the discharge reactor was a 15 kHz AC power supply with an input power of 10 W; thus obtaining the Au / CeO2 composite nanocatalyst.

[0056] The Au / CeO2 nanocatalyst obtained in Example 2 was evaluated by a water-gas shift reaction experiment. The experimental conditions were as follows: the reactant gas, composed of 10 vol% H2O and 5 vol% CO (helium balance), was discharged at a rate of 100 mL / min. -1 The total flow rate into the reactor was maintained at 120°C for the catalyst reaction. As a comparative study, catalysts subjected to untreated conditions at 550°C, H2 reduction treatment, and conventional plasma treatment were also tested and evaluated under the same conditions, with results as follows: Figure 2 As shown.

[0057] The results showed that the plasma-treated Au / CeO2 catalyst exhibited a higher CO conversion rate (89%). Under the same conditions, the catalyst treated with conventional H2 reduction had an activity of 65%, the catalyst treated with conventional H2 plasma had an activity of 73%, and the untreated catalyst had an activity of 38%. The plasma-controlled catalyst achieved the highest activity because the interaction between Au nanoparticles and CeO2 was effectively regulated. Figure 2 As shown, due to the appropriate interaction between metal nanoparticles and CeO2, the surface conversion rate of reactant CO under the same conditions is significantly increased in Au / CeO2 reduction treatment.

[0058] Example 3:

[0059] A method for in-situ plasma desolvation and stabilization of nanoparticles on the surface of metal oxides includes the following steps:

[0060] a. Measure 30 ml of anhydrous ethanol and 10 ml of glacial acetic acid separately using a graduated cylinder, weigh 17.016 g of tetrabutyl titanate and mix them together to prepare a 40 g / L palladium chloride standard solution (metal nanoparticle precursor standard solution). Measure 2.66 ml of palladium chloride solution and add it to the above mixed solution.

[0061] b. Mix and stir at 400 r / min for 5 min to prepare a 40 g / L sodium hydroxide solution. Take 6 ml of the solution and add it to the mixture. Continue to mix and stir at 400 r / min for 10 min.

[0062] c. Then transfer the above solution to a reaction vessel, keep it at 100°C for 12 hours, and then cool it to room temperature;

[0063] d. Remove the material from the reactor, discard the supernatant, add deionized water, and place it in an ultrasonic bath. First, sonicate for 10 minutes, then wash the precipitate with deionized water. After washing three times, place it in a muffle furnace and calcine at 700℃ for 4 hours to obtain the Pd-TiO2 catalyst.

[0064] e. In the dielectric barrier discharge reactor, the Pd-TiO2 catalyst was pretreated for 5 min using H2 and Ar dielectric barrier discharge plasma. The gas flow rate was 50 mL / min, the volume ratio of H2 to Ar was 1:4, and the power supply for the discharge reactor was a 15 kHz AC power supply with an input power of 10 W.

[0065] f. The activated Pd-TiO2 catalyst was retreated with H2 and Ar dielectric barrier discharge plasma for 20 min. The gas flow rate was 60 mL / min, the volume ratio of H2 to Ar was 1:5, the power supply was a 15 kHz AC power supply, and the input power was 20 W.

[0066] g. The pretreated Pd / TiO2 catalyst was activated for 5 min using O2 and Ar dielectric barrier discharge plasma, with a gas flow rate of 50 mL / min, a volume ratio of O2 to Ar of 1:2, and the power supply for the discharge reactor was a 15 kHz AC power supply with an input power of 10 W; thus obtaining the Pd / TiO2 composite nanocatalyst.

[0067] The Pd / TiO2 nanocatalyst obtained in Example 3 was evaluated by an acetylene hydrogenation reaction under the following conditions: 50 vol% C2H2, 20 vol% H2 (argon equilibrium) at 80,000 h⁻¹. -1 The space velocity flows one-way through the surface of the Pd / TiO2 catalyst. As a comparative study, catalysts treated at 700℃ (untreated), H2 reduction, and conventional plasma treatment were also tested and evaluated under the same conditions, and the results are as follows: Figure 3 As shown.

[0068] The results showed that the plasma-treated Pd / TiO2 catalyst exhibited a higher C2H2 conversion rate (99.5%). Under the same conditions, the catalyst activity after conventional H2 reduction treatment was 85.1%, the catalyst activity after conventional H2 plasma treatment was 89.6%, and the untreated catalyst activity was 70.3%. The plasma-controlled catalyst achieved the highest activity because the interaction between Pd nanoparticles and TiO2 was effectively regulated. Figure 3 As shown, due to the appropriate interaction between metal nanoparticles and TiO2, the surface conversion rate of reactant C2H2 under in-situ reduction treatment of Pd / TiO2 is significantly increased under the same conditions.

[0069] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A method for in-situ plasma desolvation and stabilization of nanoparticles on the surface of metal oxides, characterized in that, Includes the following steps: a. Weigh 4.3301g of lanthanum nitrate and 2.7356g of cobalt nitrate, dissolve them in 200ml of deionized water, and heat and stir to obtain solution A. Prepare a 40g / L chloroplatinic acid standard solution, and add 6.15ml of chloroplatinic acid to solution A. b. Heat the mixture in a water bath at 60 r / min to obtain solution B. Weigh 8.4056 g of citric acid and 5.8448 g of ethylenediaminetetraacetic acid and add them to solution B. After the particles are completely dissolved and the water bath temperature reaches 80℃, measure the pH value of the solution with a pH meter. Then, use a disposable dropper to add ammonia solution to adjust the pH value of the solution to between 7.00 and 7.

50. c. After adjusting the pH, seal the beaker with plastic wrap, and then fully complex it in a water bath at 80℃ and 60r / min for 5 hours. After that, lift the film and wait for the water to evaporate, and the solution becomes a wet gel. d. Place the obtained wet gel sample in a ceramic bowl and burn it on an electric furnace for 30-50 minutes to obtain LaCo. 0.94 Pt 0.06 O3 catalyst particles were then ground into a fine powder using a mortar and pestle, placed in a crucible, and calcined in a muffle furnace at 950°C for 7 hours. The resulting product, LaCo, was then pressed into tablets and sieved. 0.94 Pt 0.06 O3 catalyst; e. Pretreatment of LaCo using H2 and Ar dielectric barrier discharge plasma in a dielectric barrier discharge reactor. 0.94 Pt 0.06 The O3 catalyst was used for 5 min, the gas flow rate was 50 mL / min, the volume ratio of H2 to Ar was 1:4, and the power supply for the discharge reactor was a 10 kHz AC power supply with an input power of 20 W. f. Reprocessing activated LaCo using H2 and Ar dielectric barrier discharge plasma 0.94 Pt 0.06 O3 catalyst for 20 min, gas flow rate of 50 mL / min, volume ratio of H2 to Ar of 1:5, power supply of 10 kHz AC power supply, input power of 30 W; g. Pt / LaCo pretreated material activated by O2 and Ar dielectric barrier discharge plasma. 0.94 The PtyO3 catalyst was used for 5 min at a gas flow rate of 50 mL / min, the O2 to Ar volume ratio was 1:2, and the power supply for the discharge reactor was a 10 kHz AC power supply with an input power of 15 W; Pt / LaCo was obtained. 0.94 PtyO3 composite nanocatalyst.

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