CO oxidation catalyst, method for producing the same, and method for oxidizing CO

Abstract

The application relates to the technical field of CO oxidation, and particularly relates to a CO oxidation catalyst, a preparation method thereof and a CO oxidation method. The oxidation catalyst comprises a carrier and noble metal. The carrier is selected from one or more of dysprosium oxide, yttrium oxide and holmium oxide, the carrier particle size is 20 nm-100 nm, and the average particle size is 25 nm-76 nm. The noble metal is selected from one or more of platinum, ruthenium and palladium, and the noble metal element content is 0.1 wt%-2 wt% of the carrier. The CO oxidation catalyst is prepared by adopting one or more of dysprosium oxide, yttrium oxide and holmium oxide with a particle size of 20 nm-100 nm and an average particle size of 25 nm-76 nm as the carrier, the CO oxidation catalyst is used for CO catalytic oxidation, has the advantages of a lower carbon monoxide ignition temperature, and has a long service life.

Description

Technical Field

[0001] The present invention relates to the technical field of CO oxidation, and in particular to a CO oxidation catalyst and a preparation method thereof, and a CO oxidation method. Background Art

[0002] The oxidation reaction of carbon monoxide (CO) holds significant scientific and practical applications in environmental protection, industrial production, and energy conversion. As a major atmospheric pollutant, CO oxidation is crucial for improving air quality. CO released from industrial waste gas, automobile exhaust, and incomplete combustion not only threatens human health but also exacerbates the greenhouse effect and the formation of photochemical smog. Catalytic oxidation, converting CO to non-toxic CO2, has become a core technology for air pollution control, widely used in automotive three-way catalytic converters and industrial waste gas purification systems.

[0003] In recent years, noble metal-supported catalysts have been widely used due to their excellent low-temperature activity. Among the supports, rare earth oxides have significant advantages in CO oxidation due to their unique oxygen vacancy formation ability and reversible oxygen storage properties.

[0004] Therefore, the development of a catalyst for carbon monoxide oxidation based on the noble metal / rare earth oxide system and its preparation method and application method are of great significance to the control of air pollution. Summary of the Invention

[0005] The present invention aims to overcome the problems of high catalyst ignition temperature and low activity in CO oxidation reactions in the prior art, and provides a CO oxidation catalyst, a preparation method thereof, and a CO oxidation method. The present invention uses one or more of dysprosium oxide, yttrium oxide, and holmium oxide with a particle size of 20 nm to 100 nm and an average particle size of 25 nm to 76 nm as a carrier to prepare the CO oxidation catalyst. The CO oxidation catalyst is used for the catalytic oxidation of CO and has the advantages of a lower carbon monoxide ignition temperature and a long catalyst service life. In particular, further compounding a cerium-zirconium solid solution carrier as a composite carrier can further reduce the carbon monoxide ignition temperature.

[0006] To achieve the above-mentioned object, the present invention provides a CO oxidation catalyst, comprising: a carrier, a precious metal; the carrier is selected from one or more of dysprosium oxide, yttrium oxide and holmium oxide, the carrier particle size is 20 nm-100 nm, and the average particle size is 25 nm-76 nm; the precious metal is selected from one or more of platinum, ruthenium and palladium, and the precious metal element content is 0.1 wt%-2 wt% of the carrier.

[0007] The second aspect of the present invention provides a method for preparing the oxidation catalyst of the present invention, which comprises: loading the noble metal on the carrier by an impregnation method, and calcining.

[0008] A third aspect of the present invention provides a CO oxidation method, which comprises: contacting an oxygen-containing atmosphere with carbon monoxide in the presence of the oxidation catalyst of the present invention.

[0009] Through the above technical solution, the present invention uses one or more of dysprosium oxide, yttrium oxide and holmium oxide with a particle size of 20 nm to 100 nm and an average particle size of 25 nm to 76 nm as a carrier to prepare a CO oxidation catalyst. The CO oxidation catalyst is used for the catalytic oxidation of CO and has the advantages of a lower carbon monoxide ignition temperature and a long catalyst service life. In particular, further compounding a cerium-zirconium solid solution carrier as a composite carrier can further reduce the carbon monoxide ignition temperature.

[0010] The present invention also found that the CO ignition temperature can be further reduced by first loading the precious metal on one or more of dysprosium oxide, yttrium oxide and holmium oxide by impregnation, and then mixing with the cerium-zirconium solid solution carrier after calcination, grinding and then calcining. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 is the SEM image of Dy2O3 with an average particle size of 58 nm;

[0012] Figure 2 1 is a graph showing the CO oxidation performance test results of Examples 1 and 3 and Comparative Example 1;

[0013] Figure 3 is the SEM image of Dy2O3 with an average particle size of 28 nm;

[0014] Figure 4 This is a SEM image of Dy2O3 with an average particle size of 18 nm. DETAILED DESCRIPTION

[0015] The endpoints of the ranges and any values ​​disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoints of each range, the endpoints of each range and individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered to be specifically disclosed herein.

[0016] In one aspect, the present invention provides a CO oxidation catalyst, comprising: a support; and a precious metal; the support selected from one or more of dysprosium oxide, yttrium oxide, and holmium oxide, having a particle size of 20 nm to 100 nm and an average particle size of 25 nm to 76 nm; and a precious metal selected from one or more of platinum, ruthenium, and palladium, with a precious metal content of 0.1 wt% to 2 wt% of the support. The CO oxidation catalyst is prepared using one or more of the dysprosium oxide, yttrium oxide, and holmium oxide having a particle size of 20 nm to 100 nm and an average particle size of 25 nm to 76 nm as the support. The CO oxidation catalyst is used for catalytic CO oxidation, has the advantages of a lower carbon monoxide light-off temperature, and a long catalyst service life.

[0017] In the context of the present invention, including the following embodiments, dysprosium oxide, yttrium oxide and holmium oxide are tested by a BPMA field emission scanning electron microscope, and the particle size of dysprosium oxide and yttrium oxide is obtained by measuring the SEM image; the average particle size of dysprosium oxide, yttrium oxide and holmium oxide is calculated by randomly measuring the particle size of 4-10 dysprosium oxide or yttrium oxide particles in the SEM image and calculating the average value.

[0018] In the present invention, the particle size of the carrier can be, for example, 25 nm, 28 nm, 30 nm, 35 nm, 40 nm, 45 nm, 50 nm, 55 nm, 60 nm, 65 nm, 70 nm, 75 nm, 80 nm, 85 nm, 90 nm or a group consisting of any of the foregoing arrays. According to a preferred embodiment of the present invention, the particle size of the carrier is 43 nm-76 nm, and the average particle size is 43 nm-75 nm.

[0019] According to a preferred embodiment of the present invention, the specific surface area of ​​the carrier is 5 m 2 / g -50 m 2 / g.

[0020] In the present invention, one or more of dysprosium oxide, yttrium oxide and holmium oxide are used as carriers and further compounded with a cerium-zirconium solid solution carrier as a composite carrier, which can further reduce the ignition temperature of carbon monoxide. According to a preferred embodiment of the present invention, the catalyst also includes a cerium-zirconium solid solution carrier, and the mass ratio of one or more of dysprosium oxide, yttrium oxide and holmium oxide to the cerium-zirconium solid solution carrier is 1:0.4-2.5; the zirconium oxide content in the cerium-zirconium solid solution carrier is 10 wt%-80 wt%.

[0021] In the present invention, the particle size and average particle size of dysprosium oxide, yttrium oxide and holmium oxide have a significant impact on the catalytic performance of the catalyst; and the combination of cerium-zirconium solid solution and one or more of the aforementioned dysprosium oxide, yttrium oxide and holmium oxide with specific particle sizes can effectively improve the CO oxidation performance of the system catalyst.

[0022] According to a preferred embodiment of the present invention, the content of the precious metal element is 0.2 wt%-1 wt% of the carrier.

[0023] A second aspect of the present invention provides a method for preparing the oxidation catalyst described herein, comprising: loading a precious metal onto a support by an impregnation method, followed by calcination. The CO oxidation catalyst is prepared using one or more of dysprosium oxide, yttrium oxide, and holmium oxide, with a particle size of 20 nm to 100 nm and an average particle size of 25 nm to 76 nm, as a support. The CO oxidation catalyst is used for the catalytic oxidation of CO and has the advantages of a lower carbon monoxide ignition temperature and a long catalyst life.

[0024] In the present invention, there is no particular limitation on the method of loading the precious metal on the carrier by impregnation. As one embodiment of the present invention, loading the precious metal on the carrier by impregnation includes: contacting a solution containing a precious metal source with the carrier and drying.

[0025] According to a preferred embodiment of the present invention, the calcination temperature is 800-1000° C., and the calcination time is 2-16 hours.

[0026] In the above preparation method, the carrier can be one or more of dysprosium oxide, yttrium oxide and holmium oxide; or it can be a composite carrier formed by one or more of dysprosium oxide, yttrium oxide and holmium oxide and a cerium-zirconium solid solution carrier.

[0027] The present invention also found that the CO ignition temperature can be further reduced by first loading the precious metal onto one or more of dysprosium oxide, yttrium oxide, and holmium oxide by impregnation, calcining, mixing with a cerium-zirconium solid solution support, grinding, and then calcining. According to a preferred embodiment of the present invention, the preparation method of the catalyst comprises:

[0028] (1) loading the precious metal onto one or more of dysprosium oxide, yttrium oxide, and holmium oxide by an impregnation method, followed by a first calcination;

[0029] (2) The product of step (1) is mixed with the cerium-zirconium solid solution carrier, ground evenly, and then subjected to a second calcination.

[0030] According to a preferred embodiment of the present invention, the first calcination conditions include: a calcination temperature of 300-500° C., and a calcination time of 2-6 hours.

[0031] According to a preferred embodiment of the present invention, the second calcination conditions include: a calcination temperature of 800-1000° C., and a calcination time of 2-16 hours.

[0032] A third aspect of the present invention provides a CO oxidation method, which comprises: contacting an oxygen-containing atmosphere with carbon monoxide in the presence of the oxidation catalyst of the present invention.

[0033] The oxidation catalyst of the present invention can reduce the ignition temperature of carbon monoxide. According to a preferred embodiment of the present invention, the contact temperature is 30-600°C.

[0034] According to a preferred embodiment of the present invention, the mass space velocity is 50000-150000 h -1 .

[0035] According to a preferred embodiment of the present invention, the molar ratio of oxygen to carbon monoxide is 1:0.25-2.

[0036] The CO oxidation method of the present invention can catalytically oxidize CO in industrial waste gas (such as flue gas generated by steel mills and thermal power plants) and automobile exhaust at a relatively low ignition temperature.

[0037] In order to further understand the present invention, preferred embodiments of the present invention are described below in conjunction with examples. However, it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, rather than limiting the claims of the present invention.

[0038] In order to more clearly illustrate the present invention, the following examples are given, but the present invention is not limited to the scope of the examples.

[0039] In the following examples, the SEM images of Dy2O3 with a particle size of 54nm-65nm and an average particle size of 58nm are shown in FIG. Figure 1 shown.

[0040] In the following examples, the SEM images of Dy2O3 with a particle size of 27nm-30nm and an average particle size of 28nm are shown in FIG. Figure 3 shown.

[0041] In the following examples, the SEM images of Dy2O3 with a particle size of 18 nm and an average particle size of 18 nm are shown in FIG. Figure 4 shown.

[0042] Example 1

[0043] (1) 0.5 g Dy2O3 (particle size 54-65 nm, average particle size 58 nm, specific surface area 14 m 2 / g) as a carrier, platinum nitrate aqueous solution and Dy2O3 were impregnated in equal volumes at a loading rate of 1 wt% of platinum element, stirred for 4 h, dried in an 80℃ oven for 12 h, and calcined at 450℃ in air atmosphere for 4 h to obtain a precursor;

[0044] (2) The precursor and 0.5 g of cerium-zirconium solid solution (zirconium oxide content of 45 wt%) were mixed and then ground thoroughly. The ground powder was calcined at 800 °C in an air atmosphere for 10 h to obtain a catalyst.

[0045] Example 2

[0046] (1) 0.5 g Dy2O3 (particle size 27 nm-30 nm, average particle size 28 nm, specific surface area 24 m 2 / g) as a carrier, platinum nitrate aqueous solution and Dy2O3 were impregnated in equal volumes at a loading rate of 1 wt% of platinum element, stirred for 4 h, dried in an 80℃ oven for 12 h, and calcined at 450℃ in air atmosphere for 4 h to obtain a precursor;

[0047] (2) The precursor and 0.5 g of cerium-zirconium solid solution (zirconium oxide content of 45 wt%) were mixed and then ground thoroughly. The ground powder was calcined at 800 °C in an air atmosphere for 10 h to obtain a catalyst.

[0048] Example 3

[0049] 1 g Dy2O3 (particle size 54-65 nm, average particle size 58 nm, specific surface area 14 m 2 / g) as a carrier, and equal volumes of platinum nitrate aqueous solution and Dy2O3 were impregnated at a platinum loading of 0.5 wt%, stirred for 4 h, and dried in an 80°C oven for 12 h. The dried powder was ground and calcined at 800°C in air for 10 h to obtain a catalyst.

[0050] Example 4

[0051] The difference from Example 1 is that Dy2O3 and cerium-zirconium solid solution are formed into a composite carrier and then platinum is loaded. Specifically:

[0052] 0.5 g Dy2O3 (particle size 54-65 nm, average particle size 58 nm, specific surface area 14 m 2 / g) and 0.5g of cerium-zirconium solid solution (zirconium oxide content of 45 wt%) were mixed and thoroughly ground to form a carrier. An equal volume of platinum nitrate aqueous solution and the carrier were impregnated according to a platinum loading of 0.5 wt%. The mixture was stirred for 4 hours and dried in an 80°C oven for 12 hours. The mixture was calcined at 450°C in an air atmosphere for 4 hours and then calcined at 800°C in an air atmosphere for 10 hours to obtain a catalyst.

[0053] Example 5

[0054] The method of Example 1 is as follows, except that the particle size of Dy2O3 is 43nm-56nm, the average particle size is 46nm, and the specific surface area is 19 m 2 / g; other conditions are the same as in Example 1.

[0055] Example 6

[0056] The method of Example 1 is as follows, except that the particle size of Dy2O3 is 63nm-75nm, the average particle size is 70nm, and the specific surface area is 9 m 2 / g; other conditions are the same as in Example 1.

[0057] Example 7

[0058] The method of Example 1 is as follows, except that the particle size of Dy2O3 is 82nm-97nm, the average particle size is 86nm, and the specific surface area is 5 m 2 / g; other conditions are the same as in Example 1.

[0059] Example 8

[0060] (1) 0.3 g Ho2O3 (particle size 46-62 nm, average particle size 54 nm, specific surface area 15 m 2 / g) as a carrier, an aqueous solution of ruthenium chloride and Dy2O3 were impregnated in equal volumes at a loading of 3 wt% of ruthenium element, stirred for 4 h, dried in an oven at 80°C for 12 h, and calcined at 450°C in an air atmosphere for 4 h to obtain a precursor;

[0061] (2) The precursor and 0.7 g of cerium-zirconium solid solution (zirconium oxide content is 20 wt%) were mixed and then ground thoroughly. The ground powder was calcined at 1000 °C in an air atmosphere for 10 h to obtain a catalyst.

[0062] Example 9

[0063] (1) 0.7 g Y2O3 (particle size 47-69 nm, average particle size 62 nm, specific surface area 12 m 2 / g) as a carrier, palladium chloride aqueous solution and Dy2O3 were impregnated with equal volumes according to a loading amount of 0.3 wt% of palladium element, stirred for 4 h, dried in an 80℃ oven for 12 h, and calcined at 450℃ in an air atmosphere for 4 h to obtain a precursor;

[0064] (2) The precursor and 0.3 g of cerium-zirconium solid solution (zirconium oxide content of 75 wt%) were mixed and then ground thoroughly. The ground powder was calcined at 900 °C in an air atmosphere for 10 h to obtain a catalyst.

[0065] Comparative Example 1

[0066] (1) 0.5 g Dy2O3 (particle size 18 nm, average particle size 18 nm, specific surface area 31 m 2 / g) as a carrier, platinum nitrate aqueous solution and Dy2O3 were impregnated in equal volumes at a loading rate of 1 wt% of platinum element, stirred for 4 h, dried in an 80°C oven for 12 h, and calcined at 450°C in an air atmosphere for 4 h to obtain a precursor;

[0067] (2) The precursor and 0.5 g of cerium-zirconium solid solution (zirconium oxide content of 45 wt%) were mixed and then ground thoroughly. The ground powder was calcined at 800 °C in an air atmosphere for 10 h to obtain a catalyst.

[0068] Comparative Example 2

[0069] 1 g of cerium-zirconium solid solution (zirconium oxide content of 45 wt%) was used as a carrier. Equal volumes of platinum nitrate aqueous solution and cerium-zirconium solid solution were impregnated according to a platinum loading of 0.5 wt%. The mixture was stirred for 4 h and dried in an 80°C oven for 12 h. The dried powder was ground and calcined at 800°C in air for 10 h to obtain the catalyst.

[0070] The catalyst evaluation conditions were as follows: the reaction was carried out in a quartz tube with an inner diameter of 4 mm, the reaction pressure was atmospheric pressure, the reaction temperature was 30-600 °C, and the mass space velocity was 90000 h -1 , CO accounts for 1%, the molar ratio of O2 to CO is 2:1.3, and the balance is nitrogen; the heating rate is 2°C / min; the catalysts of Examples 1-9 and Comparative Examples 1-2 are tested, and the test results are shown in Table 1, wherein T 10 Refers to the temperature corresponding to 10% CO conversion rate, T 50 Refers to the temperature at which the CO conversion rate is 50%, T 90 Refers to the temperature corresponding to the CO conversion rate of 90%. The test results of Example 1, Example 3 and Comparative Example 1 are as follows Figure 2 shown.

[0071] Table 1

[0072]

[0073] Catalyst life evaluation:

[0074] The catalyst was prepared according to the method of Example 1, except that the evaluation time of the catalyst at 90% CO conversion rate (reaction temperature of 380°C) was extended to 12 hours. When the evaluation time was 12 hours, the CO conversion rate was 89.7%, which could maintain the activity of the catalyst and extend the service life of the catalyst.

[0075] The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, various simple variations of the technical solution of the present invention may be made, including combining the various technical features in any other appropriate manner. These simple variations and combinations should also be regarded as disclosed in the present invention and fall within the scope of protection of the present invention.

Claims

1. A CO oxidation catalyst, characterized in that The oxidation catalyst comprises: a carrier and a noble metal; the carrier is selected from one or more of dysprosium oxide, yttrium oxide and holmium oxide, the particle size of the carrier is 43nm-76nm, and the average particle size of the carrier is 43nm-75nm; the noble metal is selected from one or more of platinum, ruthenium and palladium, and the content of the noble metal element is 0.1wt%-2wt% of the carrier.

2. The CO oxidation catalyst according to claim 1, characterized in that The specific surface area of ​​the carrier is 5 m 2 / g -50m 2 / g.

3. The CO oxidation catalyst according to claim 1 or 2, characterized in that The CO oxidation catalyst further includes a cerium-zirconium solid solution support, wherein the mass ratio of one or more of dysprosium oxide, yttrium oxide and holmium oxide to the cerium-zirconium solid solution support is 1:0.4-2.5; and the zirconium oxide content in the cerium-zirconium solid solution support is 10 wt%-80 wt%.

4. The CO oxidation catalyst according to claim 1 or 2, characterized in that The content of the precious metal element is 0.2 wt%-1 wt% of the carrier.

5. A method for preparing the CO oxidation catalyst according to any one of claims 1 to 4, characterized in that: The method comprises: loading the noble metal on the carrier by an impregnation method, and calcining.

6. The preparation method according to claim 5, characterized in that The impregnation method of loading the precious metal on the carrier includes: contacting a solution containing a precious metal source with the carrier and drying; and / or The calcination temperature is 800-1000°C, and the calcination time is 2-16h.

7. The preparation method according to claim 5, characterized in that The method includes: (1) loading the precious metal onto one or more of dysprosium oxide, yttrium oxide, and holmium oxide by an impregnation method, followed by a first calcination; (2) The product of step (1) is mixed with the cerium-zirconium solid solution carrier, ground evenly, and then subjected to a second calcination.

8. The preparation method according to claim 7, characterized in that The first calcination conditions include: a calcination temperature of 300-500° C., a calcination time of 2-6 hours; and / or The second calcination conditions include: a calcination temperature of 800-1000° C. and a calcination time of 2-16 hours.

9. A CO oxidation method, characterized in that: The method comprises: contacting an oxygen-containing atmosphere with carbon monoxide in the presence of the CO oxidation catalyst according to any one of claims 1 to 4.

10. The CO oxidation method according to claim 9, characterized in that The contact temperature is 270-600°C; and / or Mass space velocity is 50000-150000 h -1 and / or The molar ratio of oxygen to carbon monoxide is 1:0.25-2.

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