Catalyst with high oxygen storage capacity as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of catalysts, and particularly relates to a high-oxygen-storage-capacity catalyst as well as a preparation method and application thereof. The catalyst comprises a carrier and a noble metal loaded on the carrier, the carrier is a cerium-zirconium composite oxide doped with La and Y, D90 is 5-15 [mu] m, the mass ratio of CeO2 to ZrO2 to La2O3 to Y2O3 in the cerium-zirconium composite oxide is (15-22): (65-72): (3-10): (3-10), the noble metal is Pt, and the loading capacity is 0.5-1.5 wt.%. The prepared catalyst has high oxygen storage capacity, the CO oxidation capacity in motor vehicle tail gas treatment can be improved, CO is oxidized into CO2 at the low temperature, and the catalyst is suitable for controlling emission of carbon monoxide in motor vehicle tail gas. The preparation method of the catalyst is simple and high in repeatability, electrochemical treatment is low in price and environmentally friendly, and the catalyst has very high practical value and application potential.

Description

Technical Field

[0001] The present invention belongs to the technical field of catalysts, and particularly relates to a catalyst with high oxygen storage capacity, a preparation method thereof, and an application thereof. Background Art

[0002] Carbon monoxide (CO) is one of the main pollutants in diesel vehicle exhaust, which is extremely harmful to human health. The catalytic oxidation of CO is generally considered to be the most effective method for eliminating carbon monoxide in the environment. In recent years, a large number of catalysts for CO oxidation have been developed, such as metal oxides CuO / ZnO, Fe2O3, MnO2, etc.; noble metal-based catalysts Pt / CeO2, Pt / Al2O3, etc. Generally speaking, non-noble metal-based catalysts can promote the oxidation of CO through the synergistic effect of different active components, but the activity of the catalyst is not high during cold start, and the complete conversion temperature of CO is generally higher than 150 °C. Under harsh conditions such as high humidity, the catalytic activity of non-noble metal-based catalysts will drop significantly. In contrast, noble metal-based catalysts show relatively high catalytic activity and stability for CO oxidation in the complex atmosphere during the driving of motor vehicles. The oxygen storage capacity (OSC) will significantly affect the catalytic activity of the catalyst. A catalyst with high oxygen storage capacity can release oxygen to CO at an appropriate time, quickly oxidize it to carbon dioxide (CO2), accelerate the reaction rate, improve the treatment efficiency, and can also broaden the reaction temperature window and the air-fuel ratio range, enhancing the application value. Cerium dioxide is widely used in CO oxidation due to its excellent oxygen storage capacity and flexible valence change. However, in practical applications, the catalyst usually needs to experience a high temperature above 1000 °C. After high temperature, the cerium oxide particles will undergo severe sintering, resulting in a significant decrease in specific surface area and a rapid reduction in oxygen storage capacity. By doping and modifying with transition metals (MnOx, CuO, etc.) and rare earth elements (Y, La, Pr, etc.), the thermal stability and oxygen storage capacity of cerium zirconium composite oxides are further improved. However, the process of modifying cerium zirconium composite oxides by existing methods such as co-precipitation method, surfactant template method, high-energy ball milling method, etc. is complex, with poor repeatability, long preparation time, and the energy used is non-renewable. Therefore, a reliable green preparation method needs to be developed to meet future requirements. Summary of the Invention

[0003] In order to overcome the deficiencies of the above-mentioned existing preparation technologies, the present invention provides a catalyst with high oxygen storage capacity, a preparation method thereof, and an application thereof. The present invention improves the OSC of commercially available rare earth element (La, Y) doped cerium zirconium composite oxides by using an electrochemical treatment method. The preparation method is stable, with high repeatability. The prepared catalyst has excellent oxygen storage capacity, and the required energy is clean, green, and environmentally friendly.

[0004] To achieve the above technical objectives, the technical solution adopted in the embodiments of the present invention is: In a first aspect, an embodiment of the present invention provides a catalyst with high oxygen storage capacity, which includes a carrier and a noble metal supported on the carrier. The carrier is a cerium-zirconium composite oxide doped with La and Y, and D 90 is 5 - 15 μm. By mass ratio, in the cerium-zirconium composite oxide, CeO2:ZrO2:La2O3:Y2O3 = 15 - 22: 65 - 72: 3 - 10: 3 - 10. The noble metal is Pt, and the loading amount is 0.5 - 1.5 wt.%.

[0005] Further, the cerium-zirconium composite oxide is treated by electrochemical cyclic voltammetry. The potential range used in cyclic voltammetry is -2.0 - 2.0 V vs RHE.

[0006] In a second aspect, an embodiment of the present invention provides a preparation method of the catalyst with high oxygen storage capacity described in the first aspect, including the following steps: Step S1: Dissolve 1 - 3 g of the carrier in water. After ultrasonic mixing evenly, drop it onto a glassy carbon electrode, dry it under an infrared lamp, and then perform cyclic voltammetry treatment; Step S2: Impregnate the cyclic voltammetry-treated carrier with an equal volume of a platinum nitrate glucose solution. After loading the noble metal Pt, let it stand for at least 10 h (preferably 12 - 24 h), and then calcine it in a 5 - 10% H2 / N2 atmosphere at 450 - 500 °C for 3 - 5 h. The programmed heating rate is 5 - 10 °C / min to obtain a Pt / CeZrOx-V catalyst.

[0007] Further, the cyclic voltammetry treatment in step S1 includes the following steps: Using a Pt electrode as the counter electrode, a glassy carbon electrode as the working electrode, and an Ag / AgCl electrode as the reference electrode to form a three-electrode system. Select 0.1 - 0.5 M KHCO3 as the electrolyte, start scanning from the positive potential to the negative potential, and end the scanning from the negative potential to the positive potential. The scanning rate is 30 - 50 mV / s. After scanning 50 - 1000 cycles, take out the working electrode, ultrasonically collect the cerium-zirconium composite oxide, and dry it in an oven at 60 - 80 °C for 8 - 12 h.

[0008] Further, the platinum nitrate glucose solution includes platinum nitrate and a glucose solution. The mass ratio of Pt in the platinum nitrate to the glucose solution is 1:2 - 10, and the mass percentage concentration of the glucose solution is 1 - 10%.

[0009] In a third aspect, an embodiment of the present invention provides an application of the catalyst with high oxygen storage capacity prepared in the second aspect. The catalyst is used for controlling the emission of CO in the exhaust gas of motor vehicle cold start.

[0010] Compared with the prior art, the technical solutions in the embodiments of the present invention have the following beneficial effects: In the preparation of the catalyst of the present invention, cyclic voltammetry is used to treat the carrier cerium-zirconium composite oxide. The energy used in the preparation method is clean, environmentally friendly, has high test repeatability, and the prepared catalyst has a higher OSC and excellent CO oxidation ability.

[0011] The catalyst prepared by the present invention can oxidize CO in motor vehicle exhaust to CO2 at a lower temperature under a complex atmosphere. The catalyst is environmentally friendly, the preparation process is simple, easy to operate and scale up, and the catalyst can catalytically oxidize CO in the exhaust to CO2 during the cold start process of the motor vehicle. Brief Description of the Drawings

[0012] Figure 1 is the oxygen storage capacity diagram of CeZrOx, CeZrOx-V1, CeZrOx-V2 and CeZrOx-V3 prepared at different cycle numbers at -1.2~1.2 V vs RHE. The test temperatures are 100 °C, 150 °C and 200 °C, and the space velocity is 60000 h -1 , CO / O2 switching.

[0013] Figure 2 is the oxygen storage amount of CeZrOx, CeZrOx-V2, CeZrOx-V4 and CeZrOx-V5 prepared at 100 °C when the cycle number is 500 in different voltage ranges.

[0014] Figure 3 is the CO catalytic oxidation performance diagram of Pt / CeZrOx, Pt / CeZrOx-V1, Pt / CeZrOx-V2 and Pt / CeZrOx-V3. The horizontal axis is the temperature (°C), and the left vertical axis is the conversion rate of CO (Conversion). Detailed Embodiments

[0015] In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0016] Comparative Example 1 A preparation method of a Pt / CeZrOx catalyst includes the following steps: (1) 1 g of cerium-zirconium composite oxide doped with La and Y (by mass ratio, CeO2:ZrO2:La2O3:Y2O3 = 20:70:4.5:5.5, D 90(1) Place 200 mg of cerium-zirconium composite oxide doped with La and Y (by mass ratio, CeO2:ZrO2:La2O3:Y2O3 = 20:70:4.5:5.5, D = 12.35 μm) in an agate mortar. Gradually add 1 mL of platinum nitrate glucose solution (mass ratio of Pt to glucose solution is 1:10, and the mass percentage concentration of glucose solution is 2%) dropwise to the above-mentioned cerium-zirconium composite oxide. Continuously stir and grind during the dropping process. After the dropping is completed, let the catalyst stand in an air atmosphere at room temperature (20 - 25 °C) for 12 hours, and the Pt loading is 1 wt.%. After standing, in a tubular furnace, under a 10% H2 / N2 atmosphere (the volume ratio of hydrogen in the hydrogen-nitrogen mixed gas is 10%), heat the catalyst to 450 °C at a heating rate of 5 °C / min and calcine for 4 hours to obtain Pt / CeZrOx.

[0017] Example 1 A preparation method of a high oxygen storage capacity catalyst, comprising the following steps: (1) Place 200 mg of cerium-zirconium composite oxide doped with La and Y (by mass ratio, CeO2:ZrO2:La2O3:Y2O3 = 20:70:4.5:5.5, D 90 = 12.35 μm) in water, and gradually add it dropwise to a glassy carbon electrode in four portions. After each addition, dry it with an infrared baking lamp for 30 min until all the above-mentioned cerium-zirconium composite oxide is placed on the glassy carbon electrode. Select 0.5 M KHCO3 as the electrolyte, scan from 1.2 V to -1.2 V at a scan rate of 30 mV / s for 100 cycles, then take out the working electrode, ultrasonically collect the cerium-zirconium composite oxide, and dry it overnight in an oven at 60 °C for 12 h to obtain CeZrOx-V1. Mix the CeZrOx-V1 prepared five times thoroughly to obtain 1 g of CeZrOx-V1; (2) Place 1 g of CeZrOx-V1 in an agate mortar. Gradually add 1 mL of platinum nitrate glucose solution (mass ratio of Pt to glucose solution is 1:10, and the mass percentage concentration of glucose solution is 2%) dropwise to CeZrOx-V1. Continuously stir and grind during the dropping process. After the dropping is completed, let the catalyst stand in an air atmosphere at room temperature (20 - 25 °C) for 12 hours, and the Pt loading is 1 wt.%. After standing, in a tubular furnace, under a 10% H2 / N2 atmosphere (the volume ratio of hydrogen in the hydrogen-nitrogen mixed gas is 10%), heat the catalyst to 450 °C at a heating rate of 5 °C / min and calcine for 4 hours to obtain Pt / CeZrOx-V1.

[0018] Example 2 A preparation method of a high oxygen storage capacity catalyst, comprising the following steps: (1) Place 200 mg of cerium-zirconium composite oxide doped with La and Y (by mass ratio, CeO2:ZrO2:La2O3:Y2O3 = 20:70:4.5:5.5, D90 (1) Place 200 mg of cerium-zirconium composite oxide doped with La and Y (by mass ratio, CeO2:ZrO2:La2O3:Y2O3 = 20:70:4.5:5.5, D 90 = 12.35 μm) in an aqueous solution and dropwise add it to a glassy carbon electrode in four portions. After each addition, dry it with an infrared lamp for 30 min until all of the above cerium-zirconium composite oxide is placed on the glassy carbon electrode. Select 0.5 M KHCO3 as the electrolyte and scan from 1.2 V to -1.2 V at a scan rate of 30 mV / s for 1000 cycles. Then, take out the working electrode, ultrasonically collect the cerium-zirconium composite oxide, and dry it overnight in an oven at 60 °C for 12 h to obtain CeZrOx-V3. Mix the CeZrOx-V3 prepared five times thoroughly to obtain 1 g of CeZrOx-V3; (2)Place 1 g of CeZrOx-V3 in an agate mortar and pestle, and dropwise add 1 mL of platinum nitrate glucose solution (the mass ratio of Pt to glucose solution is 1:10, and the mass percentage concentration of the glucose solution is 2%) to CeZrOx-V3. Continuously stir and grind during the dropping process. After the dropping is completed, let the catalyst stand in an air atmosphere at room temperature (20 - 25 °C) for 12 hours, and the Pt loading is 1 wt.%. After standing, in a tubular furnace, under a 10% H2 / N2 atmosphere (the volume ratio of hydrogen in the hydrogen-nitrogen mixed gas is 10%), heat the catalyst to 450 °C at a heating rate of 5 °C / min and calcine for 4 hours to prepare Pt / CeZrOx-V3.

[0019] Example 3 A preparation method of a high oxygen storage capacity catalyst, comprising the following steps: (1)Place 200 mg of cerium-zirconium composite oxide doped with La and Y (by mass ratio, CeO2:ZrO2:La2O3:Y2O3 = 20:70:4.5:5.5, D (2) Place 1 g of CeZrOx-V3 in an agate mortar. Gradually add 1 mL of a platinum nitrate glucose solution (the mass ratio of Pt to the glucose solution is 1:10, and the mass percentage concentration of the glucose solution is 2%) dropwise onto CeZrOx-V3. Continuously stir and grind during the dropping process. After the dropping is complete, let the catalyst stand in an air atmosphere at room temperature (20 - 25 °C) for 12 hours. The Pt loading is 1 wt.%. After standing, in a tubular furnace, under a 10% H2 / N2 atmosphere (the volume fraction of hydrogen in the hydrogen-nitrogen mixed gas is 10%), heat the catalyst to 450 °C at a heating rate of 5 °C / min and calcine for 4 hours to obtain Pt / CeZrOx-V3.

[0020] Example 4 A method for preparing a catalyst with high oxygen storage capacity, comprising the following steps: (1) Place 200 mg of a cerium-zirconium composite oxide doped with La and Y (by mass ratio, CeO2:ZrO2:La2O3:Y2O3 = 20:70:4.5:5.5, D 90 = 12.35 μm) in an aqueous solution. Drop it onto a glassy carbon electrode drop by drop in four portions. After each drop, dry it with an infrared lamp for 30 min until all of the above cerium-zirconium composite oxide is placed on the glassy carbon electrode. Select 0.5 M KHCO3 as the electrolyte and scan from 0.9 V to -0.9 V at a scan rate of 30 mV / s for 500 cycles. Then take out the working electrode, ultrasonically collect the cerium-zirconium composite oxide, and dry it overnight in an oven at 60 °C for 12 h to obtain CeZrOx-V4. Thoroughly mix the CeZrOx-V4 prepared five times to obtain 1 g of CeZrOx-V4; (2) Place 1 g of CeZrOx-V3 in an agate mortar. Gradually add 1 mL of a platinum nitrate glucose solution (the mass ratio of Pt to the glucose solution is 1:10, and the mass percentage concentration of the glucose solution is 2%) dropwise onto CeZrOx-V3. Continuously stir and grind during the dropping process. After the dropping is complete, let the catalyst stand in an air atmosphere at room temperature (20 - 25 °C) for 12 hours. The Pt loading is 1 wt.%. After standing, in a tubular furnace, under a 10% H2 / N2 atmosphere (the volume fraction of hydrogen in the hydrogen-nitrogen mixed gas is 10%), heat the catalyst to 450 °C at a heating rate of 5 °C / min and calcine for 4 hours to obtain Pt / CeZrOx-V4.

[0021] Example 5 A method for preparing a catalyst with high oxygen storage capacity, comprising the following steps: (1) Place 200 mg of La- and Y-doped cerium zirconium composite oxide (by mass ratio, CeO2:ZrO2:La2O3:Y2O3 = 20:70:4.5:5.5, D 90 = 12.35 μm) in an aqueous solution and dropwise add it to a glassy carbon electrode in four portions. After each addition, dry it with an infrared lamp for 30 min until all the above-mentioned cerium zirconium composite oxide is placed on the glassy carbon electrode. Select 0.5 M KHCO3 as the electrolyte and scan from 2.0 V to -2.0 V at a scan rate of 30 mV / s for 500 cycles. Then, take out the working electrode, ultrasonically collect the cerium zirconium composite oxide, and dry it overnight in an oven at 60 °C for 12 h to obtain CeZrOx-V5. Thoroughly mix the CeZrOx-V5 prepared five times to obtain 1 g of CeZrOx-V5; (2) Place 1 g of CeZrOx-V3 in an agate mortar and pestle, and dropwise add 1 mL of a platinum nitrate glucose solution (mass ratio of Pt to glucose solution is 1:10, and the mass percentage concentration of the glucose solution is 2%) to CeZrOx-V5. Continuously stir and grind during the addition process. After the addition is completed, let the catalyst stand in an air atmosphere at room temperature (20 - 25 °C) for 12 h, and the Pt loading is 1 wt.%. After standing, in a tubular furnace, under a 10% H2 / N2 atmosphere (the volume fraction of hydrogen in the hydrogen and nitrogen mixed gas is 10%), heat the catalyst to 450 °C at a heating rate of 5 °C / min and calcine for 4 h to prepare Pt / CeZrOx-V5.

[0022] Comparative Example 2 Take 300 mg (40 - 60 mesh) of the catalyst prepared in Comparative Example 1 and conduct a CO catalytic oxidation experiment in a fixed-bed quartz tube reactor (inner diameter 4 mm) under simulated automotive exhaust conditions: The reaction gas contains 4 % H2O, 0.5% CO, 1% O2, 0.2% H2, 400 ppm C2H4, 540 ppm C3H6, and 130 ppm C3H8, with N2 as the balance gas and a space velocity of 60000 h -1 , and the air-fuel ratio is 0.99.

[0023] Before testing the light-off temperature, pass 10% H2 / N2 (the volume fraction of hydrogen in the hydrogen and nitrogen mixed gas is 10%) through the sample and pretreat it at 400 °C for 1 h, then cool it to 50 °C. The feed gas is first stabilized in the bypass line for 5 minutes, and then the temperature is gradually raised to 300 °C for CO oxidation performance testing. The CO conversion rate is as Figure 3 shown.

[0024] Example 6 Take 300 mg (40 - 60 mesh) of Pt / CeZrOx-V1 prepared in Example 1 and conduct a CO catalytic oxidation experiment in a fixed-bed quartz tube reactor (inner diameter 4 mm) under simulated automotive exhaust conditions: The reaction gas contains 4 % H2O, 0.5% CO, 1% O2, 0.2% H2, 400 ppm C2H4, 540 ppm C3H6, and 130 ppm C3H8, with N2 as the balance gas and a space velocity of 60000 h -1 , and the air-fuel ratio is 0.99.

[0025] Before testing the light-off temperature, the sample is passed through 10% H2 / N2 (the volume fraction of hydrogen in the hydrogen-nitrogen mixed gas is 10%) and pretreated at 400 °C for 1 h, then cooled to 50 °C. The feed gas is first stabilized in the bypass line for 5 minutes, and then the temperature is gradually increased to 300 °C for CO oxidation performance testing. The CO conversion rate is as Figure 3 shown.

[0026] Example 7 Take 300 mg (40 - 60 mesh) of Pt / CeZrOx-V2 prepared in Example 2 and conduct a CO catalytic oxidation experiment in a fixed-bed quartz tube reactor (inner diameter 4 mm) under simulated automotive exhaust conditions: The reaction gas contains 4 % H2O, 0.5% CO, 1% O2, 0.2% H2, 400 ppm C2H4, 540 ppm C3H6, and 130 ppm C3H8, with N2 as the balance gas and a space velocity of 60000 h -1 , and the air-fuel ratio is 0.99.

[0027] Before testing the light-off temperature, the sample is passed through 10% H2 / N2 (the volume fraction of hydrogen in the hydrogen-nitrogen mixed gas is 10%) and pretreated at 400 °C for 1 h, then cooled to 50 °C. The feed gas is first stabilized in the bypass line for 5 minutes, and then the temperature is gradually increased to 300 °C for CO oxidation performance testing. The CO conversion rate is as Figure 3 shown.

[0028] Example 8 Take 300 mg (40 - 60 mesh) of Pt / CeZrOx-V3 prepared in Example 3 and conduct a CO catalytic oxidation experiment in a fixed-bed quartz tube reactor (inner diameter 4 mm) under simulated automotive exhaust conditions: The reaction gas contains 4 % H2O, 0.5% CO, 1% O2, 0.2% H2, 400 ppm C2H4, 540 ppm C3H6, and 130 ppm C3H8, with N2 as the balance gas and a space velocity of 60000 h -1 , and the air-fuel ratio is 0.99.

[0029] Before testing the light-off temperature, the sample was purged with 10% H2 / N2 (the volume fraction of hydrogen in the hydrogen-nitrogen mixed gas is 10%) and pretreated at 400 °C for 1 h, and then cooled to 50 °C. The feed gas was first stabilized in the bypass line for 5 minutes, and then the temperature was gradually increased to 300 °C for CO oxidation performance testing. The CO conversion rate is as Figure 3 shown.

[0030] It can be seen from Figure 1 that at the selected test temperatures (100 °C, 150 °C, 200 °C), CeZrOx-V1, CeZrOx-V2, and CeZrOx-V3 treated by cyclic voltammetry have higher oxygen storage capacities, and the oxygen storage capacity is related to the number of cycles. Within the selected test range, OSC 500 > OSC 1000 > OSC 100 > OSC0, where OSC 500 represents the oxygen storage capacity of the catalyst when the cyclic voltammetry is cycled 500 times.

[0031] It can be seen from Figure 2 that the oxygen storage capacity of cerium-zirconium powder changes with the change of the voltage range. When the number of cycles is 500, OSC -1.2~1.2 > OSC -0.9~0.9 > OSC -2.0~2.0 , where OSC -1.2~1.2 represents the catalyst cyclic voltammetry cycle voltage range of -2.0~2.0 V vs RHE.

[0032] It can be seen from Figure 3 that after loading Pt, Pt / CeZrOx-V1, Pt / CeZrOx-V2, and Pt / CeZrOx-V3 can reach the same CO conversion rate at a lower temperature compared with Pt / CeZrOx in Comparative Example 1, indicating that they have excellent CO oxidation ability at low temperature. This is because it can release oxygen to CO at an appropriate time, oxidize it to CO2, accelerate the reaction rate, improve the treatment efficiency, and broaden the reaction temperature window.

[0033] Finally, it should be noted that the above specific embodiments are only used to illustrate the technical solutions of the present invention and are not restrictive. Although the present invention has been described in detail with reference to the examples, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the spirit and scope of the technical solutions of the present invention, and they should all be covered within the scope of the claims of the present invention.

Claims

1. A catalyst with high oxygen storage capacity, characterized in that: The invention comprises a carrier and a noble metal loaded on the carrier, wherein the carrier is a cerium-zirconium composite oxide doped with La and Y, and D 90 The particle size is 5-15 μm. In terms of mass ratio, CeO2:ZrO2:La2O3:Y2O3 in the cerium-zirconium composite oxide is 15-22: 65-72:3-10:3-10. The precious metal is Pt, and the loading amount is 0.5-1.5 wt.%.

2. The catalyst with high oxygen storage capacity according to claim 1, characterized in that: The cerium-zirconium composite oxide is treated by electrochemical cyclic voltammetry, and the potential interval used in the cyclic voltammetry is -2.0~2.0V vs RHE.

3. The method for preparing the catalyst with high oxygen storage capacity according to claim 1, characterized in that: The following steps are involved: Step S1, dissolving 1-3 g of the carrier in water, mixing evenly by ultrasonication, dropping the mixture onto a glassy carbon electrode, drying the mixture under an infrared lamp, and performing cyclic voltammetry treatment; Step S2, impregnate an equal volume of platinum nitrate and glucose solution into the carrier treated by cyclic voltammetry, load the precious metal Pt and let it stand for at least 10 hours, then calcine in a 5-10% H2 / N2 atmosphere at 450-500°C for 3-5 hours with a programmed heating rate of 5-10°C / min to obtain a Pt / CeZrOx-V catalyst.

4. The method for preparing a catalyst with high oxygen storage capacity according to claim 3, characterized in that: The cyclic voltammetry treatment in step S1 includes the following steps: using a Pt electrode as a counter electrode, a glassy carbon electrode as a working electrode, and Ag / AgCl as a reference electrode to form a three-electrode system, selecting 0.1~0.5 M KHCO3 as an electrolyte, starting scanning from a positive potential to a negative potential, and ending scanning from a negative potential to a positive potential, the scanning rate is 30~50 mV / s, and after scanning 50~1000 circles, taking out the working electrode to collect the cerium-zirconium composite oxide by ultrasonication, and drying it in an oven at 60~80°C for 8~12 h.

5. The method for preparing a catalyst with high oxygen storage capacity according to claim 3, characterized in that: The platinum nitrate glucose solution comprises platinum nitrate and glucose solution, the mass ratio of Pt in the platinum nitrate to the glucose solution is 1:2-10, and the mass percentage concentration of the glucose solution is 1-10%.

6. Use of the catalyst with high oxygen storage capacity prepared according to claim 3, characterized in that: The catalyst is used for controlling the emission of CO in cold-start exhaust gas of motor vehicles.

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