CO oxidation catalyst, preparation method thereof and CO oxidation method

Abstract

The invention relates to the technical field of CO oxidation, in particular to a CO oxidation catalyst, a preparation method of the CO oxidation catalyst and a CO oxidation method. The carrier is selected from one or more of dysprosium oxide, yttrium oxide and holmium oxide, the particle size of the carrier is 20-100 nm, and the average particle size is 25-76 nm; the noble metal is selected from one or more of platinum, ruthenium and palladium, and the content of the noble metal element is 0.1 wt%-2wt% of the carrier. One or more of dysprosium oxide, yttrium oxide and holmium oxide with the particle size of 20-100 nm and the average particle size of 25-76 nm are adopted as the carrier to prepare the CO oxidation catalyst, and the CO oxidation catalyst is used for CO catalytic oxidation, has the advantage of lower carbon monoxide ignition temperature and is long in service life.

Description

Technical Field

[0001] The present invention 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. Background Art

[0002] The oxidation reaction of carbon monoxide (CO) has important scientific value and application significance in the fields of environmental protection, industrial production, and energy conversion. First of all, as one of the main air pollutants, the oxidation treatment of CO is a key link in improving air quality. CO released from industrial waste gases, automobile exhausts, and incomplete combustion processes not only threatens human health but also exacerbates the formation of the greenhouse effect and photochemical smog. Converting CO into non-toxic CO2 through catalytic oxidation has become the core technology for air pollution control and is widely used in automotive three-way catalytic converters and industrial waste gas purification devices.

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

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

[0005] The object of the present invention is to overcome the problems of high light-off temperature and low activity of the catalyst in the existing CO oxidation reaction, and provide 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 - 100 nm and an average particle size of 25 nm - 76 nm as the carrier to prepare a CO oxidation catalyst. The CO oxidation catalyst is used for CO catalytic oxidation, has the advantage of a lower carbon monoxide light-off temperature, and has a long service life of the catalyst. In particular, further compounding a cerium-zirconium solid solution carrier as a composite carrier can further reduce the carbon monoxide light-off temperature.

[0006] To achieve the above object, on the one hand, the present invention provides a CO oxidation catalyst, which includes: a carrier and a 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.

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

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

[0009] Through the above technical solutions, the present invention uses 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 a carrier to prepare a CO oxidation catalyst. The CO oxidation catalyst is used for CO catalytic oxidation, has the advantage of a lower carbon monoxide ignition temperature, and has a long service life of the catalyst; 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 discovers that by first loading a noble metal on one or more of dysprosium oxide, yttrium oxide and holmium oxide by impregnation, mixing and grinding with a cerium-zirconium solid solution carrier after calcination, and then calcining, the CO ignition temperature can be further reduced. Description of the Drawings

[0011] Figure 1 It is an SEM image of Dy2O3 with an average particle size of 58 nm; Figure 2 It is a graph of the CO oxidation performance test results of Example 1, 3 and Comparative Example 1; Figure 3 It is an SEM image of Dy2O3 with an average particle size of 28 nm; Figure 4 It is an SEM image of Dy2O3 with an average particle size of 18 nm. Detailed Embodiments

[0012] In the ranges disclosed herein, the endpoints and any values are not limited to the exact ranges or values, and these ranges or values should be understood to include values close to these ranges or values. For numerical ranges, between the endpoint values of each range, between the endpoint values of each range and a single point value, and between single point values, they can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed herein.

[0013] On the one hand, the present invention provides a CO oxidation catalyst, which includes: 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 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 content of the noble metal element is 0.1 wt% - 2 wt% of the carrier. Using 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 to prepare a CO oxidation catalyst, the CO oxidation catalyst is used for CO catalytic oxidation, has the advantage of a lower carbon monoxide ignition temperature, and has a long service life of the catalyst.

[0014] In the context of the specification of the present invention, including in the following embodiments, dysprosium oxide, yttrium oxide and holmium oxide are tested by a field emission scanning electron microscope of model BPMA, and the particle sizes of dysprosium oxide and yttrium oxide are measured from the SEM images; the calculation method of the average particle sizes of dysprosium oxide, yttrium oxide and holmium oxide: randomly measure the particle sizes of 4 - 10 dysprosium oxide or yttrium oxide particles in the SEM image and calculate the average value.

[0015] In the present invention, the particle size of the carrier can be, for example, 25nm, 28nm, 30nm, 35nm, 40nm, 45nm, 50nm, 55nm, 60nm, 65nm, 70nm, 75nm, 80nm, 85nm, 90nm or a group composed of any of the foregoing arrays. According to a preferred embodiment of the present invention, the particle size of the carrier is 43nm - 76nm, and the average particle size is 43 nm - 75 nm.

[0016] 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.

[0017] In the present invention, using one or more of dysprosium oxide, yttrium oxide and holmium oxide as the carrier and further compositing with a cerium zirconium solid solution carrier as a composite carrier can further reduce the carbon monoxide ignition temperature. According to a preferred embodiment of the present invention, the catalyst further 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 zirconia content in the cerium zirconium solid solution carrier is 10 wt% - 80 wt%.

[0018] In the present invention, the particle size and average particle size of dysprosium oxide, yttrium oxide and holmium oxide have a great influence on the catalyst performance of the catalyst; and the combination of the cerium zirconium solid solution with one or more of the foregoing specific particle size dysprosium oxide, yttrium oxide and holmium oxide can effectively improve the CO oxidation performance of the system catalyst.

[0019] According to a preferred embodiment of the present invention, the noble metal element content is 0.2 wt% - 1 wt% of the carrier.

[0020] The second aspect of the present invention provides a method for preparing the oxidation catalyst described in the present invention. The method includes: impregnating a noble metal on a carrier and then calcining. 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 are used as the carrier to prepare a CO oxidation catalyst. The CO oxidation catalyst is used for CO catalytic oxidation, has the advantage of a lower carbon monoxide ignition temperature, and a long service life of the catalyst.

[0021] In the present invention, there is no particular limitation on the method of impregnating a noble metal on a carrier. As an embodiment of the present invention, impregnating a noble metal on a carrier includes: contacting a solution containing a noble metal source with the carrier and then drying.

[0022] According to a preferred embodiment of the present invention, the calcination temperature is 800 - 1000 °C and the calcination time is 2 - 16 h.

[0023] 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.

[0024] The present invention also discovers that by first impregnating a noble metal on one or more of dysprosium oxide, yttrium oxide, and holmium oxide, mixing with a cerium-zirconium solid solution carrier and grinding after calcination, and then performing calcination, the CO ignition temperature can be further reduced; according to a preferred embodiment of the present invention, the preparation method of the catalyst includes: (1) Using the impregnation method to load a noble metal on one or more of dysprosium oxide, yttrium oxide, and holmium oxide, and performing the first calcination; (2) Mixing the product of step (1) with a cerium-zirconium solid solution carrier, grinding evenly, and then performing the second calcination.

[0025] 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.

[0026] 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.

[0027] The third aspect of the present invention provides a CO oxidation method, which includes: contacting an oxygen-containing atmosphere with carbon monoxide in the presence of the oxidation catalyst described in the present invention.

[0028] By using the oxidation catalyst of the present invention, the light-off temperature of carbon monoxide can be reduced. According to a preferred embodiment of the present invention, the contact temperature is 30 - 600 °C.

[0029] According to a preferred embodiment of the present invention, the mass space velocity is 50,000 - 150,000 h -1 .

[0030] According to a preferred embodiment of the present invention, the molar ratio of oxygen to carbon monoxide is 1:0.25 - 2.

[0031] The CO oxidation method of the present invention can catalytically oxidize CO in industrial waste gases (such as flue gases generated by steel mills and thermal power plants), vehicle exhaust, etc. at a lower light-off temperature.

[0032] To further understand the present invention, the preferred embodiments of the present invention will be described below in conjunction with examples. However, it should be understood that these descriptions are only for further explaining the features and advantages of the present invention, rather than limiting the claims of the present invention.

[0033] To illustrate the present invention more clearly, the following examples are listed, but the applicable situations of the present invention are not limited to the scope of the examples.

[0034] In the following examples, the SEM images of Dy2O3 with a particle size of 54 nm - 65 nm and an average particle size of 58 nm are as Figure 1 shown.

[0035] In the following examples, the SEM images of Dy2O3 with a particle size of 27 nm - 30 nm and an average particle size of 28 nm are as Figure 3 shown.

[0036] 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 as Figure 4 shown.

[0037] Example 1 (1) 0.5 g of Dy2O3 (with a particle size of 54 - 65 nm, an average particle size of 58 nm, and a specific surface area of 14 m 2 / g) was used as a carrier. A platinum nitrate aqueous solution was impregnated with Dy2O3 in an equal volume according to a loading amount of 1 wt% of platinum element, stirred for 4 h, and dried in an oven at 80 °C for 12 h; calcined in an air atmosphere at 450 °C for 4 h to obtain a precursor; (2) The precursor and 0.5 g of cerium-zirconium solid solution (with a zirconia content of 45 wt%) were mixed and ground thoroughly; the ground powder was calcined in an air atmosphere at 800 °C for 10 h to obtain a catalyst.

[0038] Example 2 (1) 0.5 g of Dy2O3 (particle size: 27 nm - 30 nm, average particle size: 28 nm, specific surface area: 24 m 2 / g) was used as the carrier. Aqueous solution of platinum nitrate was impregnated with Dy2O3 in an equal volume according to the loading amount of 1 wt% of platinum element, stirred for 4 h, and dried in an oven at 80 °C for 12 h; calcined in an air atmosphere at 450 °C for 4 h to obtain a precursor; (2) The precursor and 0.5 g of cerium-zirconium solid solution (zirconia content: 45 wt%) were mixed and ground thoroughly; the ground powder was calcined in an air atmosphere at 800 °C for 10 h to obtain the catalyst.

[0039] Example 3 1 g of Dy2O3 (particle size: 54 - 65 nm, average particle size: 58 nm, specific surface area: 14 m 2 / g) was used as the carrier. Aqueous solution of platinum nitrate was impregnated with Dy2O3 in an equal volume according to the loading amount of 0.5 wt% of platinum element, stirred for 4 h, and dried in an oven at 80 °C for 12 h; the dried powder was ground and then calcined in an air atmosphere at 800 °C for 10 h to obtain the catalyst.

[0040] Example 4 The difference from Example 1 was that platinum was loaded after forming a composite carrier of Dy2O3 and cerium-zirconium solid solution. Specifically: 0.5 g of Dy2O3 (particle size: 54 - 65 nm, average particle size: 58 nm, specific surface area: 14 m 2 / g) and 0.5 g of cerium-zirconium solid solution (zirconia content: 45 wt%) were mixed and ground thoroughly as the carrier. Aqueous solution of platinum nitrate was impregnated with the carrier in an equal volume according to the loading amount of 0.5 wt% of platinum element, stirred for 4 h, and dried in an oven at 80 °C for 12 h; calcined in an air atmosphere at 450 °C for 4 h; and then calcined in an air atmosphere at 800 °C for 10 h to obtain the catalyst.

[0041] Example 5 According to the method of Example 1, the difference was that the particle size of Dy2O3 was 43 nm - 56 nm, the average particle size was 46 nm, and the specific surface area was 19 m 2 / g; other conditions were the same as those in Example 1.

[0042] Example 6 According to the method of Example 1, the difference was that the particle size of Dy2O3 was 63 nm - 75 nm, the average particle size was 70 nm, and the specific surface area was 9 m 2 / g; other conditions were the same as those in Example 1.

[0043] Example 7 According to the method of Example 1, the difference is that the particle size of Dy2O3 is 82 nm - 97 nm, the average particle size is 86 nm, and the specific surface area is 5 m 2 / g; other conditions are the same as in Example 1.

[0044] Example 8 (1) 0.3 g of Ho2O3 (particle size 46 - 62 nm, average particle size 54 nm, specific surface area 15 m 2 / g) is used as the carrier. An aqueous solution of ruthenium chloride is impregnated with Dy2O3 in an equal volume according to a ruthenium element loading of 3 wt%, stirred for 4 h, and dried in an oven at 80 °C for 12 h; calcined in an air atmosphere at 450 °C for 4 h to obtain a precursor; (2) After mixing the precursor and 0.7 g of cerium-zirconium solid solution (zirconia content 20 wt%), grind them evenly; calcine the ground powder in an air atmosphere at 1000 °C for 10 h to obtain the catalyst.

[0045] Example 9 (1) 0.7 g of Y2O3 (particle size 47 - 69 nm, average particle size 62 nm, specific surface area 12 m 2 / g) is used as the carrier. An aqueous solution of palladium chloride is impregnated with Dy2O3 in an equal volume according to a palladium element loading of 0.3 wt%, stirred for 4 h, and dried in an oven at 80 °C for 12 h; calcined in an air atmosphere at 450 °C for 4 h to obtain a precursor; (2) After mixing the precursor and 0.3 g of cerium-zirconium solid solution (zirconia content 75 wt%), grind them evenly; calcine the ground powder in an air atmosphere at 900 °C for 10 h to obtain the catalyst.

[0046] Comparative Example 1 (1) 0.5 g of Dy2O3 (particle size 18 nm, average particle size 18 nm, specific surface area 31 m 2 / g) is used as the carrier. An aqueous solution of platinum nitrate is impregnated with Dy2O3 in an equal volume according to a platinum element loading of 1 wt%, stirred for 4 h, and dried in an oven at 80 °C for 12 h; calcined in an air atmosphere at 450 °C for 4 h to obtain a precursor; (2) After mixing the precursor and 0.5 g of cerium-zirconium solid solution (zirconia content 45 wt%), grind them evenly; calcine the ground powder in an air atmosphere at 800 °C for 10 h to obtain the catalyst.

[0047] Comparative Example 2 1 g of cerium zirconium solid solution (zirconia content is 45 wt%) was used as the carrier. Aqueous solution of platinum nitrate was impregnated with the cerium zirconium solid solution in an equal volume according to the loading amount of 0.5 wt% of platinum element, stirred for 4 h, and dried in an oven at 80 °C for 12 h. After grinding the obtained dried powder, it was calcined in an air atmosphere at 800 °C for 10 h to obtain the catalyst.

[0048] The catalyst evaluation conditions are 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 accounted for 1%, the molar ratio of O2 to CO was 2:1.3, and nitrogen was used for balance; the heating rate was 2 °C / min; the catalysts of Examples 1 - 9 and Comparative Examples 1 - 2 were tested, and the test results are shown in Table 1. Among them, T 10 refers to the temperature corresponding to a CO conversion rate of 10%, and T 50 refers to the temperature corresponding to a CO conversion rate of 50%, and T 90 refers to the temperature corresponding to a CO conversion rate of 90%. The test results of Example 1, Example 3 and Comparative Example 1 are as Figure 2 shown.

[0049] Table 1

[0050] Catalyst life evaluation: 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 was 380 °C) was extended to 12 h. When the evaluation time was 12 h, the CO conversion rate was 89.7%, the activity of the catalyst could be maintained, and the service life of the catalyst was long.

[0051] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited thereto. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solutions of the present invention, including any other suitable combination of each technical feature. These simple modifications and combinations should also be regarded as the content disclosed by the present invention and fall within the protection scope of the present invention.

Claims

1. A CO oxidation catalyst, characterized in that, The oxidation catalyst comprises: a support, and a noble metal; the support is selected from one or more of dysprosium oxide, yttrium oxide, and holmium oxide, the particle size of the support 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 content of the noble metal element is 0.1 wt% - 2 wt% of the support.

2. The CO oxidation catalyst according to claim 1, characterized in that, The particle size of the support is 43 nm - 76 nm, and the average particle size is 43 nm - 75 nm; and / or The specific surface area of the carrier is 5 m 2 / g - 50 m 2 / g.

3. The CO oxidation catalyst according to claim 1 or 2, characterized in that, The CO oxidation catalyst further comprises a cerium-zirconium solid solution support, and 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; the zirconia 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 noble metal element is 0.2 wt% - 1 wt% of the support.

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

6. The preparation method according to claim 5, characterized in that, Loading the noble metal on the support by the impregnation method comprises: contacting a solution containing a noble metal source with the support and then drying; and / or The calcination temperature is 800 - 1000 °C, and the calcination time is 2 - 16 h.

7. The preparation method according to claim 5, characterized in that, The method comprises: (1) loading the noble metal on one or more of dysprosium oxide, yttrium oxide, and holmium oxide by an impregnation method and then performing a first calcination; (2) mixing the product of step (1) with the cerium-zirconium solid solution support, grinding uniformly, and then performing a second calcination.

8. The preparation method according to claim 7, wherein The first calcination conditions include: the calcination temperature is 300 - 500 °C, and the calcination time is 2 - 6 hours; and / or The second calcination conditions include: the calcination temperature is 800 - 1000 °C, and the calcination time is 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 - 4.

10. The CO oxidation method according to claim 9, wherein The contact temperature is 30 - 600 °C; and / or The mass space velocity is 50,000 - 150,000 h -1 ; and / or The molar ratio of oxygen to carbon monoxide is 1:0.25 - 2.

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