A citric acid-assisted preparation of Pt-based catalyst for catalyzing CO oxidation and a preparation method and application thereof

Abstract

This invention relates to a Pt-based catalyst prepared with citric acid assistance for catalytic CO oxidation, its preparation method, and its application. The catalyst uses cerium oxide nanosheets as a support, Pt as the active component, and citric acid as a competing adsorbent. The Pt loading accounts for 0.5-3% of the support mass, and the citric acid addition is 0.53-8.4% of the support mass. The CeO2 nanosheet support is synthesized via precipitation, and then a certain amount of Pt and citric acid are loaded onto the support surface via citric acid-assisted strong electrostatic adsorption. Subsequently, drying and calcination yield the Pt / CeO2-x catalyst. Compared with existing technologies, the catalyst of this invention has advantages such as high activity and high stability, and has more practical application value.

Description

Technical Field

[0001] This invention belongs to the field of air pollution control, specifically relating to a Pt-based catalyst prepared with citric acid assistance for catalytic CO oxidation, its preparation method, and its application. Background Technology

[0002] CO is a significant air pollutant. It originates from the incomplete combustion of fossil fuels, primarily from industrial waste gases and vehicle exhaust. CO is flammable and explosive, and can cause dizziness, vomiting, and even shock and death. Therefore, research on CO removal technologies is of great practical importance. Among numerous CO removal technologies, low-temperature catalytic oxidation technology has attracted widespread attention due to its low reaction temperature, low energy consumption, and low risk of explosion. With societal development, the application of CO catalytic oxidation reactions is becoming increasingly widespread, demonstrating high practical value and broad application prospects in areas such as enclosed CO2 lasers, CO gas sensors, air purifiers, and CO gas respirators.

[0003] Low-temperature CO catalytic oxidation catalysts are mainly divided into noble metal catalysts and non-noble metal catalysts. Noble metal catalysts primarily refer to catalysts with noble metals such as Pt, Pd, Rh, and Au as the active component. Due to the strong activation ability of noble metals for CO, the high overall reaction stability, and the long lifespan, noble metal catalysts have become a research focus for low-temperature CO catalytic oxidation reactions. However, noble metal catalysts, especially Pt-based catalysts, face problems such as CO poisoning and poor stability. Therefore, based on the actual application requirements of CO oxidation technology, improving the CO poisoning resistance and stability of noble metal catalysts and developing highly active and stable CO catalytic oxidation catalysts is of great significance. Summary of the Invention

[0004] The purpose of this invention is to overcome the defects of the prior art by providing a Pt-based catalyst for catalytic CO oxidation prepared with citric acid assistance, its preparation method, and its application. This catalyst has high activity and high stability, solving the problems of high ignition temperature and poor stability of supported Pt catalysts prepared by traditional methods.

[0005] The objective of this invention can be achieved through the following technical solution: A Pt-based catalyst prepared with citric acid assistance for catalytic CO oxidation, wherein the catalyst uses cerium oxide nanosheets as a support, Pt as the active component, and citric acid as a competitive adsorbent, wherein the loading of Pt accounts for 0.5-3% of the support mass, and the amount of citric acid added is 0.53-8.4% of the support mass.

[0006] Furthermore, the carrier is prepared by precipitation method, specifically including the following steps: ammonium bicarbonate and cerium nitrate are dissolved in deionized water and stirred in a water bath at 25-35℃ (preferably 30℃). After complete dissolution, the ammonium bicarbonate solution is rapidly poured into the cerium nitrate solution in a water bath at 25-35℃ (preferably 30℃), and the reaction is carried out with rapid stirring for 20-30 min (preferably 25 min). Then, it is placed in a 30℃ oven and allowed to stand for 24 h. After that, it is filtered and washed multiple times, dried in an oven at 75-85℃ (preferably 80℃) for 20-30 h (preferably 24 h), and finally calcined in air at 450-550℃ (preferably 500℃) for 3-5 h (preferably 4 h) with a heating rate of 2-3℃ / min (preferably 2.5℃ / min) to obtain cerium oxide nanosheets.

[0007] Furthermore, the mass ratio of ammonium bicarbonate to cerium nitrate is 1:1~2.

[0008] Further, the loading of Pt is 1.5-2.5% of the carrier mass, and the addition of citric acid is 1-3% of the carrier mass. More preferably, the loading of Pt is 2% of the carrier mass, and the addition of citric acid is 2.1% of the carrier mass.

[0009] This invention also provides a method for preparing a Pt-based catalyst for catalytic CO oxidation using citric acid assistance, characterized by comprising the following steps:

[0010] Citric acid monohydrate was added to deionized water and stirred to dissolve. The pH was then adjusted to 2.5-3.5 with dilute nitric acid. Cerium oxide nanosheets were then added and ultrasonically dispersed to obtain a cerium oxide nanosheet dispersion.

[0011] After adjusting the pH of deionized water to 2.5-3.5 with dilute nitric acid, a soluble salt of Pt was added. The resulting Pt impregnation solution was added dropwise to a continuously stirred cerium oxide nanosheet dispersion at a rate of 0.5-1.5 mL / min. After the addition was complete, stirring was continued for 3-5 h. The solution was then filtered and washed multiple times, the filter cake was dried, and finally calcined in air at 400-500℃ for 3-5 h at a heating rate of 1.5-2℃ / min, preferably 1.8℃ / min, to obtain the catalyst product, labeled as 2Pt / CeO2-x.

[0012] Furthermore, the Pt impregnation solution is prepared by dissolving chloroplatinic acid in deionized water to prepare a Pt impregnation solution of 15-25 mg / mL, preferably 20 mg / mL.

[0013] The present invention also provides an application of a Pt-based catalyst prepared with citric acid to catalyze CO oxidation, wherein the catalyst is used to catalyze CO oxidation in a temperature range of 25-500°C.

[0014] Furthermore, the reaction conditions for the catalytic oxidation of CO were: 1 vol.% CO, 20 vol.% O2, 79 vol.% N2, and a mass hourly space velocity (WHSV) of 30,000 mL·h. -1 ·g cat -1 .

[0015] Compared with the prior art, the present invention has the following advantages:

[0016] 1. The Pt / CeO2-x catalyst of this invention uses CeO2 nanosheets as a support, loading a certain amount of Pt, and adding citric acid as a competitive adsorbent during the preparation process. Citric acid is first mixed with CeO2 nanosheets for adsorption. After adding the active component Pt, because the support is dispersed in an aqueous solution and the pH is adjusted to be lower than the isoelectric point of the support (CeO2 isoelectric point is around 6.3), the support surface is positively charged. The citric acid and chloroplatinic acid used in the preparation process are both anions. These anions will generate strong electrostatic adsorption with the positively charged support in the aqueous phase, thus loading the active component onto the support. The active component and the competitive adsorbent... The additive is loaded using a strong electrostatic adsorption method. After high-temperature calcination, citric acid decomposes and is removed, and Pt species are spread evenly on CeO2 nanosheets, forming PtOx active species. The evenly spread structure of Pt increases the contact area between CO and the support, promoting the adsorption and activation of CO and O2, as well as the reaction between CO* and O*. The PtOx active species can react with activated CO* at room temperature to generate carbonate / bicarbonate intermediates, which greatly inhibits the poisoning effect of CO on noble metal species. Therefore, the catalyst of this invention has the advantages of high activity and high stability, and has more practical application value.

[0017] 2. The Pt / CeO2-x catalyst of this invention is used for the catalytic oxidation of CO. Adding specific amounts of citric acid and Pt helps improve the catalyst's activity and stability. When the citric acid content is 21 mg, catalysts with different Pt loadings all exhibit better CO catalytic oxidation activity than other catalysts with the same Pt ​​content. When the citric acid content is 21 mg and the Pt content is 2%, the 2Pt / CeO2-21 catalyst exhibits the best CO catalytic oxidation activity, completely oxidizing CO at 155 °C (1 vol.% CO, 20 vol.% O2, 79% N2, mass hourly space velocity: 30000 mL·h). -1 ·g cat -1 Furthermore, the catalyst exhibits excellent reaction stability, demonstrating superior catalytic activity even in long-term reaction stability tests (where CO conversion remained consistent over 50 hours).

[0018] 3. This invention synthesizes CeO2 nanosheet support by precipitation, and then loads a certain amount of Pt onto the surface of the support by strong electrostatic adsorption assisted by citric acid. Subsequently, the Pt / CeO2-x catalyst is obtained by drying and calcination. The method is simple and easy to industrialize. Moreover, the use of citric acid not only reduces the amount of precious metal Pt used and lowers the cost, but also improves the activity and stability of the catalyst. Attached Figure Description

[0019] Figure 1 shows the CO catalytic oxidation activity of the catalysts obtained in Examples 1-4 and Comparative Examples 1-4. Specifically, Figure 1a The graphs show the CO catalytic oxidation activity of the catalysts obtained in Example 1 and Comparative Example 1. Figure 1b The graphs show the CO catalytic oxidation activity of the catalysts obtained in Example 2 and Comparative Example 2. Figure 1c The graphs show the CO catalytic oxidation activity of the catalysts obtained in Example 3 and Comparative Example 3. Figure 1d The diagram shows the CO catalytic oxidation activity of the catalysts obtained in Example 4 and Comparative Example 4.

[0020] Figure 2 The diagram shows the CO oxidation activity of the 2Pt / CeO2-21 catalyst obtained in Example 3 and the catalysts in Comparative Examples 3 and 5.

[0021] Figure 3 The graph shows the CO catalytic oxidation stability test results of the 2Pt / CeO2-21 catalyst obtained in Example 3 and the catalysts of Comparative Examples 3 and 5. Detailed Implementation

[0022] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0023] Example 1:

[0024] A Pt-based catalyst for CO oxidation prepared with citric acid assistance and its preparation method:

[0025] (1) Preparation of cerium oxide nanosheets

[0026] 3g of ammonium bicarbonate and 5.56g of cerium nitrate were dissolved separately in 200mL of deionized water and stirred in a 30°C water bath. After both solutions were fully dissolved, the ammonium bicarbonate solution was quickly poured into the cerium nitrate solution in a 30°C water bath while stirring for 30min. Then, the mixture was placed in a 30°C oven and allowed to stand for 24h. After repeated filtration and washing, it was dried overnight in an 80°C oven and finally calcined in air at 500°C for 4h at a heating rate of 2.5°C / min.

[0027] (2) Preparation of 0.5Pt / CeO2-x catalyst:

[0028] The loading of Pt was 0.5 wt.%, and the addition of citric acid was 21 mg. 21 mg of citric acid monohydrate was added to 200 mL of deionized water, stirred to dissolve, and the pH was adjusted to 3.0 with dilute nitric acid. Then, 1 g of cerium oxide nanosheets was added, and the mixture was ultrasonically dispersed for 15 min. A 20 mg / mL fresh chloroplatinic acid impregnation solution was prepared. 200 mL of deionized water was adjusted to pH 3.0 with dilute nitric acid, and 0.25 mL of the Pt impregnation solution was added. The Pt solution was then added dropwise to the continuously stirred cerium oxide nanosheet dispersion at a rate of 1 mL / min using a peristaltic pump. After the addition was complete, stirring was continued for 4 h. The mixture was then filtered and washed multiple times. The filter cake was dried overnight in an oven at 80°C, and finally calcined in air at 450°C for 4 h at a heating rate of 1.8°C / min to obtain the cerium oxide-supported platinum catalyst labeled 0.5Pt / CeO2-21.

[0029] Catalysts 0.5Pt / CeO2-5.3, 0.5Pt / CeO2-42, and 0.5Pt / CeO2-84 were synthesized using the same preparation method. Here, 5.3 indicates that 5.3 mg of citric acid was added per 1 g of cerium oxide nanosheets. Similarly, 42 and 84 indicate that the mass of citric acid added per gram of cerium oxide nanosheets was 42 mg and 84 mg, respectively. The 0.5Pt / CeO2 catalyst was synthesized using the same method as Comparative Example 1 (i.e., no citric acid was added).

[0030] Catalyst activity test:

[0031] The calcined catalyst was pressed into tablets, sieved (60-80 mesh particles were collected), and its CO catalytic oxidation activity was evaluated in a gas-solid phase fixed-bed microreactor (6 mm inner diameter). The catalyst dosage was 50 mg, and the temperature was automatically controlled using thermocouples. Oxygen was used as the oxidant, with a carbon monoxide concentration of 1 vol.%, an oxygen concentration of 20 vol.%, and N2 as the balance gas. The mass hourly space velocity (WHSV) was 30,000 mL·h. -1 ·g cat -1 The reaction pressure was atmospheric pressure. The test results are shown in Figure 1. Figure 1a The graph shows the CO catalytic oxidation activity of the 0.5Pt / CeO2-x catalyst. It can be seen that when the citric acid content is 21 mg, the 0.5Pt / CeO2-x catalyst exhibits the best CO catalytic oxidation activity. 90 The temperature at which 90% conversion is achieved is 227°C, which is higher than the Tconversion of the 0.5Pt / CeO2 catalyst. 90 The temperature was reduced by 93°C. The results showed that when the amount of citric acid added was 21 mg, the activity of the 0.5Pt / CeO2-x catalyst was significantly improved, and the activity decreased rapidly with further increases in the amount of citric acid.

[0032] Example 2:

[0033] A Pt-based catalyst for catalytic CO oxidation prepared with citric acid assistance and its preparation method thereof

[0034] (1) Preparation of cerium oxide nanosheets

[0035] 3g of ammonium bicarbonate and 5.56g of cerium nitrate were dissolved separately in 200mL of deionized water and stirred in a 30°C water bath. After both solutions were fully dissolved, the ammonium bicarbonate solution was quickly poured into the cerium nitrate solution in a 30°C water bath while stirring for 30min. Then, the mixture was placed in a 30°C oven and allowed to stand for 24h. After repeated filtration and washing, it was dried overnight in an 80°C oven and finally calcined in air at 500°C for 4h at a heating rate of 2.5°C / min.

[0036] (2) Preparation of 1Pt / CeO2-x catalyst:

[0037] The loading of Pt was 1 wt.%, and the addition of citric acid was 21 mg. 21 mg of citric acid monohydrate was added to 200 mL of deionized water, stirred to dissolve, and the pH was adjusted to 3.0 with dilute nitric acid. Then, 1 g of cerium oxide nanosheets was added, and the mixture was ultrasonically dispersed for 15 min. A 20 mg / mL fresh chloroplatinic acid impregnation solution was prepared. 200 mL of deionized water was adjusted to pH 3.0 with dilute nitric acid, and 0.5 mL of the Pt impregnation solution was added. The Pt solution was then added dropwise to the continuously stirred cerium oxide nanosheet dispersion at a rate of 1 mL / min using a peristaltic pump. After the addition was complete, stirring was continued for 4 h. The mixture was then filtered and washed multiple times. The filter cake was dried overnight in an oven at 80°C, and finally calcined in air at 450°C for 4 h at a heating rate of 1.8°C / min to obtain the cerium oxide-supported platinum catalyst labeled 1Pt / CeO2-21.

[0038] Catalysts 1Pt / CeO2-5.3, 1Pt / CeO2-10.6, 1Pt / CeO2-42 and 1Pt / CeO2-84 were synthesized using the same preparation method, and 1Pt / CeO2 was synthesized using the same method as Comparative Example 2.

[0039] The CO catalytic oxidation activity of the above-mentioned synthesized samples was tested, and the results are as follows: Figure 1b As shown, the T90 of the 1Pt / CeO2 catalyst is 297°C. With increasing citric acid addition, the CO catalytic oxidation activity of the 1Pt / CeO2-x catalyst gradually increases. When the citric acid addition is 21 mg, the activity of the 1Pt / CeO2-x catalyst reaches its optimal value, with a T90 of [value missing]. 90 The temperature was 198°C. With further increases in citric acid content, the catalytic oxidation activity of the catalyst for CO decreased rapidly, and T... 90The temperature was increased to above 300°C. The above results indicate that when the Pt content is 1%, adding 21 mg of citric acid during the preparation process can significantly improve the catalyst's CO catalytic oxidation activity.

[0040] Example 3:

[0041] A Pt-based catalyst for catalytic CO oxidation prepared with citric acid assistance and its preparation method thereof

[0042] (1) Preparation of cerium oxide nanosheets

[0043] 3g of ammonium bicarbonate and 5.56g of cerium nitrate were dissolved separately in 200mL of deionized water and stirred in a 30°C water bath. After both solutions were fully dissolved, the ammonium bicarbonate solution was quickly poured into the cerium nitrate solution in a 30°C water bath while stirring for 30min. Then, the mixture was placed in a 30°C oven and allowed to stand for 24h. After repeated filtration and washing, it was dried overnight in an 80°C oven and finally calcined in air at 500°C for 4h at a heating rate of 2.5°C / min.

[0044] (2) Preparation of 2Pt / CeO2-x catalyst:

[0045] The loading of Pt was 2 wt.%, and the addition of citric acid was 21 mg. 21 mg of citric acid monohydrate was added to 200 mL of deionized water, stirred to dissolve, and the pH was adjusted to 3.0 with dilute nitric acid. Then, 1 g of cerium oxide nanosheets was added, and the mixture was ultrasonically dispersed for 15 min. A 20 mg / mL fresh chloroplatinic acid impregnation solution was prepared. 200 mL of deionized water was adjusted to pH 3.0 with dilute nitric acid, and 1 mL of the Pt impregnation solution was added. The Pt solution was then added dropwise to the continuously stirred cerium oxide nanosheet dispersion at a rate of 1 mL / min using a peristaltic pump. After the addition was complete, stirring was continued for 4 h. The mixture was then filtered and washed multiple times. The filter cake was dried overnight in an oven at 80°C, and finally calcined in air at 450°C for 4 h at a heating rate of 1.8°C / min to obtain the cerium oxide-supported platinum catalyst labeled 2Pt / CeO2-21.

[0046] Catalysts 2Pt / CeO2-5.3, 2Pt / CeO2-10.6, 2Pt / CeO2-42 and 2Pt / CeO2-84 were synthesized using the same preparation method, and 2Pt / CeO2 was synthesized using the same method as Comparative Example 3.

[0047] The CO catalytic oxidation activity of the above-mentioned synthesized samples was tested, and the results are as follows: Figure 1c As shown: T of the 2Pt / CeO2 catalyst 90 At 284°C, when the amount of citric acid added is 21 mg, T 90 The temperature dropped significantly to 150°C when the added amount was 42 mg, T90 The initial temperature was 151°C. With increasing citric acid addition to 84 mg, the T90 of the 2Pt / CeO2-42 catalyst increased to 262°C. These results indicate that the activity of the 2Pt / CeO2-x catalyst was significantly improved when the citric acid addition was 21 mg.

[0048] Example 4:

[0049] A Pt-based catalyst for catalytic CO oxidation prepared with citric acid assistance and its preparation method thereof

[0050] (1) Preparation of cerium oxide nanosheets

[0051] 3g of ammonium bicarbonate and 5.56g of cerium nitrate were dissolved separately in 200mL of deionized water and stirred in a 30°C water bath. After both solutions were fully dissolved, the ammonium bicarbonate solution was quickly poured into the cerium nitrate solution in a 30°C water bath while stirring for 30min. Then, the mixture was placed in a 30°C oven and allowed to stand for 24h. After repeated filtration and washing, it was dried overnight in an 80°C oven and finally calcined in air at 500°C for 4h at a heating rate of 2.5°C / min.

[0052] (2) Preparation of 3Pt / CeO2-x catalyst:

[0053] The loading of Pt was 3 wt.%, and the addition of citric acid was 21 mg. 21 mg of citric acid monohydrate was added to 200 mL of deionized water, stirred to dissolve, and the pH was adjusted to 3.0 with dilute nitric acid. Then, 1 g of cerium oxide nanosheets was added, and the mixture was ultrasonically dispersed for 15 min. A 20 mg / mL fresh chloroplatinic acid impregnation solution was prepared. 200 mL of deionized water was adjusted to pH 3.0 with dilute nitric acid, and 1.5 mL of the Pt impregnation solution was added. The Pt solution was then added dropwise to the continuously stirred cerium oxide nanosheet dispersion at a rate of 1 mL / min using a peristaltic pump. After the addition was complete, stirring was continued for 4 h. The mixture was then filtered and washed multiple times. The filter cake was dried overnight in an oven at 80°C, and finally calcined in air at 450°C for 4 h at a heating rate of 1.8°C / min to obtain the cerium oxide-supported platinum catalyst labeled 3Pt / CeO2-21.

[0054] Catalysts 3Pt / CeO2-5.3, 3Pt / CeO2-10.6, 3Pt / CeO2-42 and 3Pt / CeO2-84 were synthesized using the same preparation method, and 3Pt / CeO2 was synthesized using the same method as Comparative Example 4.

[0055] The CO catalytic oxidation activity of the above-mentioned synthesized samples was tested, and the results are as follows: Figure 1d As shown, the T of the 3Pt / CeO2 catalyst 90The optimal temperature for CO catalytic oxidation was 298°C; when the citric acid content was increased to 21 mg, the 3Pt / CeO2-21 exhibited the best CO catalytic oxidation activity. 90 The temperature dropped to 267°C; with further increases in citric acid content, T... 90 The temperature was increased to 322°C. This indicates that the 3Pt / CeO2-x catalyst exhibits optimal activity when the citric acid content is 21 mg. Compared with Examples 1-3, the Pt / CeO2 catalyst shows the best CO catalytic oxidation activity when the Pt content is 2% and the citric acid content is 21 mg.

[0056] Comparative Example 5:

[0057] A Pt-based catalyst for CO oxidation and its preparation method

[0058] (1) Preparation of cerium oxide nanosheets

[0059] 3g of ammonium bicarbonate and 5.56g of cerium nitrate were dissolved separately in 200mL of deionized water and stirred in a 30°C water bath. After both solutions were fully dissolved, the ammonium bicarbonate solution was quickly poured into the cerium nitrate solution in a 30°C water bath while stirring for 30min. Then, the mixture was placed in a 30°C oven and allowed to stand for 24h. After repeated filtration and washing, it was dried overnight in an 80°C oven and finally calcined in air at 500°C for 4h at a heating rate of 2.5°C / min.

[0060] (2) Preparation of 2Pt / CeO2IWI catalyst:

[0061] The cerium oxide-supported platinum catalyst was prepared by an equal-volume impregnation method with a Pt loading of 2 wt.%. A fresh chloroplatinic acid impregnation solution of 20 mg / mL was prepared. 1 mL of the Pt impregnation solution and 0.2 mL of deionized water were added to 1 g of cerium oxide nanosheets, stirred and ultrasonically mixed, allowed to stand for 24 h, and then dried overnight in an oven at 80°C. Finally, it was calcined in air at 450°C for 4 h at a heating rate of 1.8°C / min to obtain the cerium oxide-supported platinum catalyst labeled 2Pt / CeO2IWI.

[0062] The CO catalytic oxidation activity of Comparative Example 5 synthesized above was tested and compared with that of the 2Pt / CeO2 and 2Pt / CeO2-21 catalysts involved in Example 3. The results are as follows: Figure 2The 2Pt / CeO2-21 catalyst showed significantly better CO oxidation activity than the 2Pt / CeO2 and 2Pt / CeO2IWI catalysts, with a T90 reduction of 130°C. The activity of the 2Pt / CeO2IWI catalyst was slightly lower than that of the 2Pt / CeO2 catalyst. These results indicate that the Pt / CeO2 catalyst prepared by the strong electrostatic adsorption method exhibits slightly better CO oxidation activity than the catalyst prepared by the equal-volume impregnation method, and the addition of citric acid can effectively improve the CO oxidation activity of the catalyst.

[0063] Long-term stability test

[0064] The reaction was investigated under the following conditions (1 vol.% CO, 20 vol.% O2, 79% N2, mass hourly space velocity: 30000 mL·h). -1 ·g cat -1 The long-term stability of CO catalytic oxidation reaction of the 2Pt / CeO2, 2Pt / CeO2-21 catalysts in Example 3 and the 2Pt / CeO2IWI catalyst in Comparative Example 5 was determined at the reaction temperature T for each catalyst. 90 The result is as follows Figure 3 As shown, the CO conversion rate of 2Pt / CeO2 rapidly decreased to 80% in the first 1 hour of the reaction, and the CO activity was around 65% after 50 hours, with significant fluctuations. The CO catalytic oxidation activity of the 2Pt / CeO2-21 catalyst was very stable, remaining at 90% without increasing with reaction time. These results indicate that the addition of citric acid significantly increases the stability of CO catalytic oxidation of 2Pt / CeO2, while the CO oxidation activity of the 2Pt / CeO2-21 catalyst remained unchanged over 50 hours.

[0065] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A Pt-based catalyst prepared with citric acid assistance for catalytic CO oxidation, characterized in that, The catalyst uses cerium oxide nanosheets as a support, Pt as the active component, and citric acid as a competitive adsorbent. The loading of Pt accounts for 0.5-3% of the support mass, and the amount of citric acid added is 0.53-8.4% of the support mass. The catalyst is prepared by the following method: citric acid monohydrate is added to deionized water, stirred and dissolved, and the pH is adjusted to 2.5-3.

5. Then, cerium oxide nanosheets are added and ultrasonically dispersed to obtain a cerium oxide nanosheet dispersion. After adjusting the pH of deionized water to 2.5-3.5, a soluble salt of Pt was added. The resulting Pt impregnation solution was added dropwise to a continuously stirred cerium oxide nanosheet dispersion at a rate of 0.5-1.5 mL / min. After the addition was complete, stirring was continued for 3-5 h. The mixture was then filtered and washed multiple times, the filter cake was dried, and finally calcined in air at 400-500℃ for 3-5 h at a heating rate of 1.5-2℃ / min to obtain the catalyst product. In the obtained catalyst, Pt species were evenly distributed on CeO2 nanosheets, forming platinum oxide active species.

2. The Pt-based catalyst for catalytic CO oxidation prepared with citric acid assistance according to claim 1, characterized in that, The carrier is prepared by precipitation method, specifically including the following steps: ammonium bicarbonate and cerium nitrate are dissolved in deionized water and reacted by rapid stirring in a water bath, then dried, washed, and calcined to obtain cerium oxide nanosheets.

3. The Pt-based catalyst for catalytic CO oxidation prepared with citric acid assistance according to claim 2, characterized in that, The mass ratio of ammonium bicarbonate to cerium nitrate is 1:1~2.

4. The Pt-based catalyst for catalytic CO oxidation prepared with citric acid assistance according to claim 2, characterized in that, The water bath temperature is 25-35℃, and the water bath reaction time is 20-30 minutes; The drying temperature is 75-85℃, and the drying time is 20-30 hours. The calcination is carried out in air at 450-550℃ for 3-5 hours, with a heating rate of 2-3℃ / min.

5. The Pt-based catalyst for catalytic CO oxidation prepared with citric acid assistance according to claim 1, characterized in that, The loading of Pt is 1.5-2.5% of the carrier mass, and the addition of citric acid is 1-3% of the carrier mass.

6. A method for preparing a Pt-based catalyst for catalytic CO oxidation using citric acid assistance as described in any one of claims 1-5, characterized in that, Includes the following steps: Citric acid monohydrate was added to deionized water, stirred and dissolved, and the pH was adjusted to 2.5-3.

5. Then, cerium oxide nanosheets were added and ultrasonically dispersed to obtain a cerium oxide nanosheet dispersion. After adjusting the pH of deionized water to 2.5-3.5, a soluble salt of Pt was added. The resulting Pt impregnation solution was added dropwise to a continuously stirred cerium oxide nanosheet dispersion at a rate of 0.5-1.5 mL / min. After the addition was complete, stirring was continued for 3-5 h. The solution was then filtered and washed multiple times, the filter cake was dried, and finally calcined in air at 400-500℃ for 3-5 h at a heating rate of 1.5-2℃ / min to obtain the catalyst product.

7. The method for preparing the Pt-based catalyst for catalytic CO oxidation with citric acid assistance according to claim 6, characterized in that, The Pt impregnation solution is prepared by dissolving chloroplatinic acid in deionized water to prepare a Pt impregnation solution with a concentration of 15-25 mg / mL.

8. The method for preparing the Pt-based catalyst for catalytic CO oxidation with citric acid assistance according to claim 6, characterized in that, The pH value was adjusted using dilute nitric acid.

9. The application of a Pt-based catalyst prepared with citric acid assistance for catalytic CO oxidation as described in any one of claims 1-5, characterized in that, The catalyst was used to catalyze the oxidation of CO in a temperature range of 25-500℃.

10. The application of the Pt-based catalyst prepared with citric acid assistance for catalytic CO oxidation according to claim 9, characterized in that, The reaction conditions for the catalytic oxidation of CO were: 1 vol.% CO, 20 vol.% O2, 79 vol.% N2, and a mass hourly space velocity (WHSV) of 30,000 mL·h. -1 ·g cat -1 .

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