Rare earth modified Pt-based catalyst for catalytic oxidation of CO and preparation method thereof

Abstract

The invention discloses a rare earth modified Pt-based catalyst for catalytic oxidation of CO and a preparation method thereof, and belongs to the field of environmental engineering. The low-temperature CO oxidation catalyst which takes Pt as a main active component, one or two or more of Er2O3, Eu2O3 and Sm2O3 as auxiliaries and TiO2 as a carrier is prepared by adopting a two-step impregnation method. The preparation process is simple, and large-scale production and market popularization and application are easy. The catalyst can be used for realizing complete CO conversion at 120-130 DEG C, has good sulfur and water resistance (15% H2O and 50 ppm SO2) performance under the conditions of low temperature (200 DEG C) and low oxygen (5% O2), keeps the CO removal efficiency at 99% or above after testing for 72 hours, and can be used for removing CO in tail gas of sintering, coking, heating furnaces and the like through a catalytic oxidation method and recovering reaction heat at the same time.

Description

Technical Field

[0001] This invention relates to a rare earth-modified Pt-based catalyst for the catalytic oxidation of CO and its preparation method. It can be used to remove CO from tail gases of sintering, coking, and heating furnaces, while recovering the heat of reaction, thus achieving efficient utilization of resources. It belongs to the field of environmental engineering. Background Technology

[0002] Waste gas emitted from steel sintering, coking, and other production processes contains large amounts of CO. Due to its colorless, odorless, and highly toxic properties, it is considered a very dangerous and harmful gas, attracting increasing attention, and various regions have introduced CO-related emission standards. Catalytic oxidation is considered the most effective and economical method for CO removal due to its high efficiency and low-temperature reaction. However, the low temperature of sintering flue gas in the steel industry, along with the presence of certain concentrations of SO2 and H2O, can poison CO oxidation catalysts. Therefore, improving the low-temperature activity and sulfur and water resistance of CO oxidation catalysts is crucial for their industrial application.

[0003] CN117123259A discloses a method for preparing a sulfur-resistant Pt-based CO oxidation catalyst and the catalyst itself. The method utilizes the large anionic groups in the ammonium phosphomolybdate within the modified support to adsorb Pt from a platinum nitrate solution. 2+ A sulfur-resistant Pt-based CO oxidation catalyst was prepared using this method. The resulting catalyst achieved a high CO conversion rate at 160–180 °C and operated stably at 220 °C, 50 ppm SO2, and 10% H2O. However, the catalyst in this method suffers from poor low-temperature CO oxidation activity and a high sulfur-resistant temperature.

[0004] CN111185167B discloses a Pt-based catalyst for CO purification, its preparation method, and its uses. The Pt-based catalyst uses TiO2 as a support, with Pt as the main active component, CeO2 as the first co-active component, and WO3 and / or MoO3 as the second co-active component. This Pt-based catalyst exhibits high CO catalytic oxidation efficiency and sulfur resistance. However, this method suffers from a high operating temperature (220 °C) under simulated flue gas conditions (CO content 7200 ppm, O2 content 16%, SO2 content 50~500 ppm, N2 as the balance gas).

[0005] CN108855069B discloses a method for preparing a nanorod-shaped Pt / CeO2 supported catalyst. The method uses a Ce-containing metal-organic framework as a template / precursor, utilizing the porosity and large specific surface area of ​​the metal-organic framework to load Pt nanoparticles onto its surface. Subsequent drying and high-temperature calcination treatments yield a nanorod-shaped Pt / CeO2 supported catalyst for low-temperature CO catalytic oxidation. The prepared catalyst has advantages such as low Pt loading, good dispersibility, and controllable microstructure. It also exhibits excellent low-temperature CO catalytic oxidation performance. However, the catalyst preparation method in this scheme is complex, making mass production difficult and limiting its industrial application prospects.

[0006] CN113680352A discloses a low-loading Pt-Mn bimetallic catalyst for CO oxidation, its preparation method, and its application. This invention uses TiO2 as a support, with elemental Pt and / or Pt oxides as the first active component and manganese oxides as the second active component. The synergistic effect between the first and second active components significantly reduces the amount of precious metals Pt and Mn used. Compared with traditional catalysts, this catalyst exhibits high resistance to water and sulfur, low loading of active components, and high CO oxidation efficiency. However, this approach also suffers from the problem of high operating temperature (240 °C) under simulated flue gas conditions (CO content 7000 ppm, O2 content 16%, H2O content 10%, SO2 content 50~500 ppm, N2 as the balance gas).

[0007] Furthermore, previous studies have shown that adding an appropriate amount of CeO2 can significantly improve the CO catalytic oxidation activity and SO2 resistance of Pt / TiO2 catalysts. This effect is attributed to the increase in adsorbed oxygen species and the preferential binding of CeO2 with SO2. Therefore, modifying Pt-based catalysts with other rare earth oxides is a promising strategy to simultaneously improve low-temperature CO oxidation activity and sulfur resistance.

[0008] The purpose of this invention is to provide a rare earth-modified Pt-based catalyst for catalytic oxidation of CO and its preparation method. The catalyst is simple to prepare, suitable for large-scale production, and has excellent catalytic performance. It can achieve complete CO conversion at 120~130 ℃ and has good sulfur and water resistance under low temperature (200 ℃) and low oxygen (5% O2) atmosphere conditions. Summary of the Invention

[0009] To address the characteristics of low-temperature sintering flue gas in the steel industry, which contains high concentrations of CO and certain concentrations of SO2 and H2O, this invention provides a rare-earth-modified Pt-based catalyst for the catalytic oxidation of CO and its preparation method. The rare-earth oxide is precisely deposited near the noble metal Pt, which not only improves the dispersion of Pt but also provides new adsorption sites for H2O and SO2, effectively protecting the Pt sites from poisoning by H2O and SO2. The catalyst preparation process is simple, suitable for large-scale production, and exhibits excellent catalytic performance, achieving complete CO conversion at 120–130 °C. Furthermore, the catalyst demonstrates good resistance to sulfur and water (15% H2O, 50 ppm SO2) under low-temperature (200 °C) and low-oxygen (5% O2) atmospheres, maintaining a catalytic CO oxidation efficiency of over 99% after 72 hours of testing.

[0010] The technical solution of the present invention is as follows:

[0011] A rare earth-modified Pt-based catalyst for catalytic oxidation of CO, characterized in that Pt is the main active component, one or more of Er2O3, Eu2O3, and Sm2O3 are used as promoters, and TiO2 is used as a support; the contents of each component of the catalyst are as follows: the content of active component Pt is 0.1~2 wt%, the content of promoter components Er2O3 and / or Eu2O3 and / or Sm2O3 is 0.5~5 wt%, and the content of support component TiO2 is 93.0~99.5 wt%.

[0012] The preparation method of the rare earth-modified Pt-based catalyst for catalytic oxidation of CO includes the following specific steps:

[0013] (1) Weigh the catalyst support component TiO2 and the corresponding nitrate and / or chloride salt precursor raw materials of the promoter;

[0014] (2) Mix the weighed carrier component TiO2 and deionized water evenly by mechanical stirring and / or ball milling, and then add the weighed auxiliary precursor raw material and continue to mix evenly by mechanical stirring and / or ball milling.

[0015] (3) Place the suspension obtained in step (2) in a water bath at 60~80 ℃ and stir with microwave or / and ultrasonic for 2~6 h; dry the resulting paste at 110 ℃;

[0016] (4) Grind the dried sample from step (3) into powder and calcine it at 300~600 ℃ in air atmosphere for 1~5 h; after natural cooling, the modified carrier is obtained.

[0017] (5) Weigh the modified support obtained in step (4), add deionized water and mix evenly by mechanical stirring and / or ball milling, then add the precursor of the active component Pt of the catalyst; place the resulting suspension in a water bath at 60~80 ℃ and stir by microwave or / and ultrasonic for 2~6 h; dry the resulting paste at 110 ℃.

[0018] (6) Grind the sample dried in step (5) into powder and calcine it at 300~600 ℃ in air atmosphere for 1~5 h; after natural cooling, a rare earth modified Pt-based catalyst is obtained. After screening out catalyst particles of a certain size, it is stored under sealed and dry conditions.

[0019] The precursor raw materials for the auxiliary agent Er2O3 mentioned in step (1) are selected from one or both of erbium nitrate and erbium chloride. The precursor raw materials for the auxiliary agent Eu2O3 are selected from one or both of europium nitrate and europium chloride. The precursor raw materials for the auxiliary agent Sm2O3 are selected from one or both of samarium nitrate and samarium chloride.

[0020] The precursor of Pt mentioned in step (6) is one or more of platinum nitrate, platinum chloride, and chloroplatinic acid.

[0021] The catalyst obtained by this invention is used for the catalytic oxidation of CO; complete CO conversion can be achieved at 120~130 °C; it has good resistance to sulfur and water (15% H2O, 50 ppm SO2) under low temperature (200 °C) and low oxygen (5% O2) conditions, and is used for the catalytic oxidation of CO under conditions with H2O and SO2.

[0022] The advantages of this invention are as follows:

[0023] 1. The catalyst prepared by the method described in this invention has good low-temperature catalytic CO oxidation performance, and complete CO conversion can be achieved at 120~130℃.

[0024] 2. The catalyst prepared by the method described in this invention has good resistance to sulfur and water (15% H2O, 50 ppm SO2) under low temperature (200 ℃) and low oxygen (5% O2) conditions, and still has a catalytic CO oxidation efficiency of over 99% after 72 h of testing.

[0025] 3. The catalyst preparation process is simple, and it is easy to scale up production and promote its application in the market. Attached Figure Description

[0026] Figure 1 The diagram shows the low-temperature activity of the CO catalysts obtained in Examples 1, 2, and 3.

[0027] Figure 2 The figures show the sulfur and water resistance effects of the CO catalysts obtained in Examples 1, 2, and 3. Detailed Implementation

[0028] The present invention will be further described below with reference to the embodiments, but the present invention is not limited to the following embodiments.

[0029] Example 1 (Comparison):

[0030] Weigh 12.2 g of titanium dioxide, add deionized water and stir until homogeneous. Then add 20 mL of a 5 g / L platinum nitrate solution. Place the suspension in an ultrasonic cleaner, heat to 75 °C in a water bath, and continue stirring for 4 h. After stirring, dry in an oven at 110 °C. Then grind the dried sample into powder and place it in a muffle furnace. Heat to 500 °C at a rate of 3 °C / min and maintain for 3 h. After cooling, sieve the catalyst to obtain particles of 20-40 mesh, seal and store, and designate it as sample 1# (the specific composition of sample 1# is 0.5 wt% Pt and 99.5 wt% TiO2).

[0031] Example 2:

[0032] Weigh 15 g of titanium dioxide, add deionized water and stir until homogeneous, then add 0.71 g of erbium nitrate. Place the suspension in an ultrasonic cleaner, heat to 75 ℃ in a water bath and continue stirring for 4 h. After stirring, dry in an oven at 110 ℃. Then grind the dried sample into powder and place it in a muffle furnace, heat to 500 ℃ at a rate of 3 ℃ / min and hold for 3 h. After naturally cooling to room temperature, the Er2O3-TiO2 modified support is obtained.

[0033] Weigh 12.2 g of Er2O3-TiO2 modified support, add deionized water and stir until homogeneous. Then add 20 mL of 5 g / L platinum nitrate solution. Place the suspension in an ultrasonic cleaner, heat to 75 ℃ in a water bath and continue stirring for 4 h. After stirring, dry in an oven at 110 ℃. Then grind the dried sample into powder and place it in a muffle furnace, heating to 500 ℃ at a rate of 3 ℃ / min and holding for 3 h. After cooling, sieve the catalyst through a 20-40 mesh sieve, seal and store, and designate it as sample #2 (the specific composition of sample #2 is 0.5 wt% Pt, 2 wt% Er2O3, and 97.5 wt% TiO2).

[0034] Example 3:

[0035] Weigh 15 g of titanium dioxide, add deionized water and stir until homogeneous, then add 0.78 g of europium nitrate. Place the suspension in an ultrasonic cleaner, heat to 75 ℃ in a water bath and continue stirring for 4 h. After stirring, dry in an oven at 110 ℃. Then grind the dried sample into powder and place it in a muffle furnace, heat to 500 ℃ at a rate of 3 ℃ / min and hold for 3 h. After naturally cooling to room temperature, the Eu2O3-TiO2 modified support is obtained.

[0036] Weigh 12.2 g of Eu2O3-TiO2 modified support, add deionized water and stir until homogeneous. Then add 20 mL of 5 g / L platinum nitrate solution. Place the suspension in an ultrasonic cleaner, heat to 75 ℃ in a water bath and continue stirring for 4 h. After stirring, dry in an oven at 110 ℃. Then grind the dried sample into powder and place it in a muffle furnace, heating to 500 ℃ at a rate of 3 ℃ / min and holding for 3 h. After cooling, sieve the catalyst through a 20-40 mesh sieve, seal and store, and designate it as sample #3 (the specific composition of sample #3 is 0.5 wt% Pt, 2 wt% Eu2O3, and 97.5 wt% TiO2).

[0037] Test Example 1:

[0038] CO catalytic oxidation experiments were conducted using catalyst #1 from Example 1, catalyst #2 from Example 2, and catalyst #3 from Example 3, respectively. The flue gas composition during the tests was: CO content 8000 ppm, O2 content 5%, N2 as the balance gas, and a mass hourly space velocity (MSV) of 45000 mL g. -1 h -1 The CO catalytic efficiency of each catalyst as a function of temperature is shown in the following curves. Figure 1 As shown in the figure, the lowest temperature at which catalyst #1 achieves complete CO conversion is 140 ℃, while the lowest complete CO conversion temperatures for catalysts #2 and #3 are 130 ℃ and 120 ℃, respectively. This demonstrates that rare earth modification effectively improves the low-temperature activity of Pt-based catalysts for CO catalytic oxidation.

[0039] Test Example 2:

[0040] Sulfur and water resistance experiments were conducted on CO catalysts using catalyst #1 from Example 1, catalyst #2 from Example 2, and catalyst #3 from Example 3 as examples. The flue gas composition during the tests was: CO content 8000 ppm, O2 content 5%, H2O content 15%, SO2 content 50 ppm, N2 as the balance gas, and a mass hourly space velocity (MSV) of 45000 mL g. -1 h -1 The test temperature was 200 ℃. The CO catalytic efficiency of each catalyst versus time curves are shown below. Figure 2As shown, during the 72-hour sulfur and water resistance test, the CO conversion rate of catalyst #1 exhibited a slight fluctuation but generally decreased, dropping from an initial 100% to a final 77.8%. In contrast, catalysts #2 and #3 maintained a CO conversion rate exceeding 99% throughout the entire 72-hour sulfur and water resistance test. Clearly, rare earth modification improved the sulfur and water resistance performance of the Pt-based catalysts.

Claims

1. A rare earth modified Pt-based catalyst, characterized in that, The catalyst comprises Pt as the main active component, one or more of Er2O3, Eu2O3 and Sm2O3 as the auxiliary component, and TiO2 as the carrier; the content of each component is as follows: the content of the active component Pt is 0.1-2 wt%, the content of the auxiliary component Er2O3 or / and Eu2O3 or / and Sm2O3 is 0.5-5 wt%, and the content of the carrier component TiO2 is 93.0-99.5 wt%.

2. Process for the preparation of the catalyst according to claim 1, characterized in that, The method comprises the following steps: (1) weighing the carrier component TiO2 and the auxiliary component nitrate or / and chloride precursor; (2) mixing the carrier component TiO2 and the auxiliary component precursor in deionized water by mechanical stirring or / and ball milling, and then adding the auxiliary component precursor and continuing to mix by mechanical stirring or / and ball milling; (3) placing the suspension obtained in step (2) in a water bath at 60-80 ℃, and stirring by microwave or / and ultrasonic for 2-6 h; drying the obtained paste at 110 ℃; (4) grinding the dried sample in step (3) into powder, and then calcining the powder at 300-600 ℃ in air for 1-5 h; and obtaining the modified carrier after natural cooling; (5) weighing the modified carrier obtained in step (4), adding deionized water and mixing by mechanical stirring or / and ball milling, and then adding the active component Pt precursor; placing the obtained suspension in a water bath at 60-80 ℃, and stirring by microwave or / and ultrasonic for 2-6 h; and drying the obtained paste at 110 ℃; (6) grinding the dried sample in step (5) into powder, and then calcining the powder at 300-600 ℃ in air for 1-5 h; and obtaining the rare earth modified Pt-based catalyst after natural cooling; and sealing and storing the catalyst particles with a certain particle size under dry conditions.

3. The method of claim 1, wherein, The auxiliary component Er2O3 precursor in step (1) is one or both of erbium nitrate and erbium chloride; the auxiliary component Eu2O3 precursor is one or both of europium nitrate and europium chloride; and the auxiliary component Sm2O3 precursor is one or both of samarium nitrate and samarium chloride.

4. The method of claim 1, wherein, The Pt precursor in step (6) is one or more of platinum nitrate, platinum chloride and chloroplatinic acid.

5. The use of the catalyst of claim 1 for catalyzing the oxidation of CO.

6. The use according to claim 5, wherein the complete conversion of CO is achieved at 120-130 ℃.

7. Use according to claim 5 for the catalytic oxidation of CO under low temperature 200 °C, low oxygen 5% O 2、 15% H2O, 50 ppm SO2 conditions.

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