A modified platinum-based catalyst for room-temperature catalytic oxidation of CO and its preparation method and application

Abstract

The present invention discloses a modified platinum-based catalyst for room-temperature catalytic oxidation of CO, its preparation method, and application, belonging to the field of catalyst technology. The preparation method of the modified platinum-based catalyst comprises the following steps: modifying an aluminum-based carrier using a manganese metal compound solution to obtain a manganese-modified aluminum-based carrier; loading platinum on the manganese-modified aluminum-based carrier to obtain a platinum-loaded manganese-modified aluminum-based carrier; and subjecting the platinum-loaded manganese-modified aluminum-based carrier to a water vapor-assisted treatment to obtain the modified platinum-based catalyst for room-temperature catalytic oxidation of CO; the manganese metal compound solution comprises a manganese source and a urea solution. The catalyst preparation process is simple and can be industrially mass-produced. Furthermore, the catalyst can achieve catalytic oxidation of CO at room temperature with a catalytic life of up to 190 hours, providing a solution for room-temperature CO removal and enabling the widespread use of gas masks.

Description

Technical Field

[0001] The present invention belongs to the technical field of catalysts, and more particularly relates to a modified platinum-based catalyst for catalytic oxidation of CO at room temperature, and a preparation method and application thereof. Background Art

[0002] Fire is one of the major disasters that seriously affects human life, property and safety. Fires in residential areas not only cause property damage but also seriously affect the personal safety of residents. Among the various toxic gases in fire smoke, CO is recognized as the main toxic gas that causes a large number of people to die from poisoning in fires. CO is a colorless, odorless, and suffocating toxic gas. CO can bind to hemoglobin in human red blood cells, reducing the oxygen transport capacity. The symptoms and signs of CO poisoning are related to the carboxyhemoglobin saturation (COHb%) in the blood. The COHb% of the vast majority of people who die from CO poisoning in fires is 50-70%. Equipping homes with fire-fighting equipment such as gas masks that can remove CO toxic gas in fires can enable timely self-rescue and reduce loss of life. Therefore, it is of great significance to develop catalysts that can efficiently remove CO at ambient temperature and humidity.

[0003] At present, the interlayer of the gas mask mostly uses hopcalite catalyst, the main component of the catalyst is CuO-MnO x Composite oxides. Although hopcalite catalysts are highly active and low-cost, their service life can only reach 30 minutes due to their poor moisture resistance and they need to be replaced regularly. Precious metal catalysts show high activity in low-temperature CO oxidation and have a long catalytic service life. However, it is difficult for single platinum catalysts to catalyze the oxidation of CO at room temperature. Existing platinum-based catalysts improve the activity and stability of the catalyst during the CO oxidation reaction by doping with transition metals such as nickel, cobalt, and titanium, but there is a technical problem of low activity at ambient temperature and humidity, and they are all flaky or granular catalysts, which are difficult to use in CO protection gas masks. Therefore, it is of great significance to develop a catalyst that has high activity at ambient temperature and humidity and can be used in CO protection gas masks. Summary of the Invention

[0004] The present invention aims to provide a modified platinum-based catalyst for room-temperature catalytic oxidation of CO, a preparation method thereof, and an application thereof, so as to solve the problems of low activity of existing platinum-based catalysts at ambient temperature and humidity, and the inability to be used in CO protection gas masks due to the catalyst morphology.

[0005] To achieve the above object, the present invention provides the following solutions:

[0006] One of the technical solutions of the present invention is to provide a method for preparing a modified platinum-based catalyst for catalytic oxidation of CO at room temperature, comprising the following steps:

[0007] An aluminum-based support is modified using a manganese metal compound solution to obtain a manganese-modified aluminum-based support; platinum is loaded on the manganese-modified aluminum-based support to obtain a platinum-loaded manganese-modified aluminum-based support; and the platinum-loaded manganese-modified aluminum-based support is subjected to a water vapor-assisted treatment to obtain the modified platinum-based catalyst for room-temperature catalytic oxidation of CO;

[0008] The present invention reduces the activation energy of the CO reaction on the catalyst surface by doping with transition metal manganese, thereby promoting the catalytic oxidation reaction of CO to occur more easily; and, by modifying the transition metal manganese, the water dissociation energy on the catalyst surface is greatly reduced, prompting the surface to produce more hydroxyl active species that are beneficial to the catalytic oxidation reaction of CO, thereby improving the activity of the catalyst in catalytic oxidation of CO at room temperature. In addition, by subjecting the catalyst to water vapor-assisted treatment, the catalyst is given a suitable amount of hydroxyl groups. Through water vapor-assisted treatment, the physically adsorbed water and -OH on the catalyst surface increase, and the physically adsorbed water molecules dissociate on the MnO2 surface to produce a large amount of -OH. The -OH group plays an important role in catalytic oxidation, especially in catalytic reactions with "CO+-OH" as the reaction path, thereby improving the catalytic activity of the catalyst. Manganese is used as the modifying material and platinum is used as the doping precious metal, and the water vapor-assisted treatment is used in conjunction to produce more hydroxyl active groups on the catalyst surface;

[0009] In the preparation process of the aluminum-based support, the porous anodized aluminum substrate is first calcined to obtain the porous anodized aluminum oxide (AAO); the hydroxyl-rich boehmite (AlOOH) is obtained through a hot hydration reaction; and the aluminum-based support (γ-Al2O3 support) with a dense and ordered porous structure is obtained through a second calcination. Using the γ-Al2O3 support as the aluminum-based support can optimize the active sites for CO catalytic oxidation. Platinum atoms are bonded to the Al on the surface of γ-Al2O3 through oxygen bridges. 3+ Site binding, which makes these sites coordination saturated (pentahedral to octahedral conversion), thereby optimizing the active site;

[0010] The manganese metal compound solution includes a manganese source and a urea solution; urea is selected to undergo an oxidation-reduction reaction with the manganese source, and no organic by-products are generated.

[0011] Preferably, in the manganese metal compound solution, the concentration of the manganese source is 0.01 to 0.06 mol / L, and the concentration of urea is 0.2 to 0.8 mol / L; the manganese source includes one or more of manganese sulfate, manganese acetate tetrahydrate, manganese nitrate and potassium permanganate; the modification step includes: placing the aluminum-based support in the manganese metal compound solution for impregnation, and then roasting; the temperature for impregnation of the aluminum-based support in the manganese metal compound solution is 50 to 95° C., and the time for impregnation in the manganese metal compound solution is 8 to 16 hours; the temperature for roasting is 350 to 500° C., and the time for roasting is 2 to 5 hours.

[0012] Preferably, the step of loading platinum on the manganese-modified aluminum-based carrier comprises: placing the manganese-modified aluminum-based carrier in a platinum-containing solution for impregnation, and then chemically reducing it; the concentration of the platinum compound in the platinum-containing solution is 0.05 to 1.25 g / L; the impregnation temperature is 50 to 95° C., and the impregnation time is 1 to 6 hours.

[0013] Preferably, the platinum compound in the platinum-containing solution includes chloroplatinic acid, tetraammineplatinum hydroxide hydrate or tetraammineplatinum chloride hydrate.

[0014] Preferably, the chemical reduction step comprises: placing the impregnated product in a sodium borohydride solution for reduction; the concentration of the sodium borohydride solution is 1 to 3 g / L; the reduction temperature is 25 to 45° C., and the reduction time is 1 to 12 hours.

[0015] The present invention uses a sodium borohydride solution for reduction. During the reduction process, sodium borohydride generates a large amount of hydrogen gas, which produces bubbles and localized solution disturbances. This gas release promotes the formation of manganese nanoparticles or nanosheets, resulting in increased surface roughness. Furthermore, the rapid gas release during the reduction reaction creates pores on the material surface, forming a porous structure. This porous structure increases the material's specific surface area and significantly alters its surface morphology.

[0016] Preferably, the preparation steps of the aluminum-based support are as follows: the aluminum substrate is anodized and then subjected to a first calcination, a hot water hydration reaction and a second calcination in sequence to obtain the aluminum-based support; the aluminum substrate comprises an aluminum mesh; the conditions for the anodization are: the electrolyte is an oxalic acid solution, the temperature is 15-35°C, the current density is 20-35A / m 2 , time is 4 to 16 hours; the temperature of the first calcination and the second calcination is independently 350 to 550°C; the time of the first calcination is 1 to 5 hours; the time of the second calcination is 3 to 6 hours; the temperature of the hot water hydration reaction is 30 to 95°C, and the time of the hot water hydration reaction is 60 to 120 minutes.

[0017] More preferably, the concentration of the oxalic acid solution is 0.1 to 0.8 mol / L.

[0018] Preferably, the water vapor-assisted treatment step includes: using air at a certain flow rate to treat the platinum-loaded manganese-modified aluminum-based carrier through a container filled with water; the air flow rate is 20 to 50 mL / min; the water vapor-assisted treatment volume is 0 to 3 L, excluding 0 L; water vapor-assisted treatment volume = air flow rate × time.

[0019] The second technical solution of the present invention: provides a modified platinum-based catalyst for catalytic oxidation of CO at room temperature prepared by the preparation method of the modified platinum-based catalyst for catalytic oxidation of CO at room temperature.

[0020] Preferably, in the modified platinum-based catalyst for room-temperature catalytic oxidation of CO, the manganese loading is 4-6 wt%, and the platinum loading is 1-3 wt%.

[0021] The third technical solution of the present invention: provides the use of the modified platinum-based catalyst for catalytic oxidation of CO at room temperature in a CO protection gas mask.

[0022] The fourth technical solution of the present invention is to provide a method for catalytic oxidation of CO at room temperature, specifically, using the modified platinum-based catalyst described in claim 8 as a catalyst for catalytic oxidation of CO at room temperature.

[0023] The present invention discloses the following technical effects:

[0024] 1. The present invention reduces the activation energy of CO reaction on the catalyst surface by doping with transition metal manganese, making the CO catalytic oxidation reaction easier to occur; and, by modifying the transition metal manganese, the water dissociation energy on the catalyst surface is greatly reduced, prompting the surface to produce more hydroxyl active species that are beneficial to the CO catalytic oxidation reaction, thereby improving the catalyst's activity in catalytic oxidation of CO at room temperature. In addition, by performing water vapor-assisted treatment on the catalyst, the catalyst is given an appropriate amount of hydroxyl groups. Achieved at 26000mL / (g cat At a gas hourly space velocity of 1.1 sq ft (1.1 sq ft) per hour (h), 0.58 g of a modified platinum-based catalyst for room-temperature catalytic oxidation of CO achieved 100% CO conversion at 25°C. The development of a structured modified platinum-based catalyst for room-temperature catalytic oxidation of CO provides a solution for room-temperature CO removal and enables the widespread use of gas masks.

[0025] 2. The modified platinum-based catalyst for room-temperature catalytic oxidation of CO of the present invention has a simple preparation process and is amenable to industrial mass production. Furthermore, the catalyst can catalytically oxidize CO at room temperature, resolving the problem of existing catalysts requiring high temperatures for catalytic oxidation of CO.

[0026] 3. The modified platinum-based catalyst for room-temperature catalytic oxidation of CO described in the present invention has a catalytic life of up to 190 hours for CO catalytic oxidation at room temperature and has excellent room-temperature catalytic stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a flow chart for preparing a modified platinum-based catalyst for room-temperature catalytic oxidation of CO according to the present invention;

[0028] Figure 2The device and flow chart for CO catalytic reaction experiments;

[0029] Figure 3 Cross-sectional FESEM images of the catalysts prepared in Comparative Example 1(a), Example 2(b), Example 3(c) and Example 4(d) at different magnifications;

[0030] Figure 4 Graphs showing the CO conversion rates of the catalysts prepared in Comparative Example 1, Example 1, Example 2, Example 3, and Example 4 at 25°C; wherein a is a graph showing the CO conversion rate, and b is a graph showing the average CO conversion rate; in b, fresh represents Comparative Example 1, H-0.9L represents Example 1, H-1.8L represents Example 2, H-3L represents Example 3, and H-6L represents Example 4;

[0031] Figure 5 This is a lifespan diagram of the catalyst prepared in Example 2 catalyzing CO at room temperature (25°C).

[0032] Figure 6 The CO conversion results of the catalysts prepared in Comparative Example 1, Comparative Example 2, Comparative Example 3, Comparative Example 4, and Comparative Example 5 at 25°C are shown;

[0033] Figure 7 The CO conversion rate results of the catalysts prepared in Comparative Examples 6, 8, 9, 10, and 11 at 25°C are shown; wherein a is the CO conversion rate result graph, and b is the CO average conversion rate result graph; in b, fresh represents Comparative Example 6, H-0.9L represents Comparative Example 8, H-1.8L represents Comparative Example 9, H-3L represents Comparative Example 10, and H-6L represents Comparative Example 11;

[0034] Figure 8 The CO conversion results of the catalysts prepared in Comparative Examples 7, 12, 13, 14, and 15 at 25°C are shown; wherein a is a CO conversion result graph, and b is a CO average conversion result graph; in b, fresh represents Comparative Example 7, H-0.9L represents Comparative Example 12, H-1.8L represents Comparative Example 13, H-3L represents Comparative Example 14, and H-6L represents Comparative Example 15;

[0035] Figure 9 The CO conversion rate results of the catalysts prepared in Comparative Example 5, Comparative Example 16, Comparative Example 17, Comparative Example 18 and Comparative Example 19 at 25°C are shown; wherein a is the CO conversion rate result graph, and b is the CO average conversion rate result graph; in b, fresh represents Comparative Example 5, H-0.9L represents Comparative Example 16, H-1.8L represents Comparative Example 17, H-3L represents Comparative Example 18, and H-6L represents Comparative Example 19. DETAILED DESCRIPTION

[0036] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0037] It should be understood that the terms described herein are intended only to describe particular embodiments and are not intended to limit the present invention. In addition, for numerical ranges herein, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. The intermediate value within any stated value or stated range, and each smaller range between any other stated value or intermediate value within the stated range, is also encompassed within the present invention. The upper and lower limits of these smaller ranges may be independently included or excluded within the scope.

[0038] Unless otherwise indicated, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art. Although only preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein may also be used in the practice or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of any conflict with any incorporated document, the contents of this specification shall prevail.

[0039] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments described herein without departing from the scope or spirit of the invention. Other embodiments will be apparent to those skilled in the art from the description of the invention. The description and examples are intended to be illustrative only.

[0040] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0041] Unless otherwise specified, the reagents used in the examples and comparative examples are all commercially available reagents.

[0042] The normal temperature in the embodiments of the present invention is 20-30°C.

[0043] The modified platinum-based catalyst obtained in the embodiment of the present invention is not limited to use at room temperature, it can also be used at high temperature. The following only emphasizes the use effect at room temperature just to highlight the advantages of the modified platinum-based catalyst obtained in the present invention compared with the existing catalyst.

[0044] Example 1

[0045] Dilute the aluminum cleaning agent (available in the market, any similar existing product) to a concentration of 3-6 wt% and soak the aluminum mesh at room temperature for 10 minutes. Place it in an anodizing tank at 20°C and a current density of 25 A / m 2 The α-Al2O3 support was anodized in a 0.3 mol / L oxalic acid solution for 8 h. After rinsing with deionized water and air drying, it was calcined at 450°C for 1 h. It was then hydrated in deionized water at 70°C for 60 min and dried at room temperature. It was then calcined at 500°C for 4 h to obtain the γ-Al2O3 support.

[0046] The obtained γ-Al2O3 support was placed in a mixed solution consisting of manganese sulfide and urea solution (manganese sulfide concentration was 0.02 mol / L, urea concentration was 0.2 mol / L), impregnated at 90°C for 15 h, and calcined at 450°C for 3 h to obtain a Mn / γ-Al2O3 / Al catalyst.

[0047] The Mn / γ-Al2O3 / Al catalyst was placed in a 7.5 g / L chloroplatinic acid aqueous solution, immersed at 80°C for 2 h, washed with deionized water, placed in a 2 g / L sodium borohydride aqueous solution, reduced at 35°C for 4 h, and dried at room temperature for 12 h to obtain a manganese-modified precious metal catalyst, recorded as Pt / Mn / γ-Al2O3 / Al.

[0048] Air with a flow rate of 30 mL / min was passed through a washing bottle filled with deionized water, and Pt / Mn / γ-Al2O3 / Al was subjected to water vapor assisted treatment at room temperature (25°C). The water vapor treatment volume was 0.9 L, and a modified platinum-based catalyst was prepared, which was recorded as Pt / Mn / γ-Al2O3 / Al-0.9L.

[0049] The modified platinum-based catalyst obtained in this example is in a structured network shape, which has the advantages of low pressure drop, good mass and heat transfer, and easy plasticity, and can be used in gas masks for CO protection.

[0050] Example 2

[0051] The difference from Example 1 is that the water vapor treatment volume is 1.8 L, and the rest is the same as Example 1. The prepared modified platinum-based catalyst is recorded as Pt / Mn / γ-Al2O3 / Al-1.8L.

[0052] The modified platinum-based catalyst obtained in this example is in a structured network shape, which has the advantages of low pressure drop, good mass and heat transfer, and easy plasticity, and can be used in gas masks for CO protection.

[0053] Example 3

[0054] The difference from Example 1 is that the water vapor treatment volume is 3 L, and the other parameters are the same as Example 1. The prepared modified platinum-based catalyst is recorded as Pt / Mn / γ-Al2O3 / Al-3L.

[0055] The modified platinum-based catalyst obtained in this example is in a structured network shape, which has the advantages of low pressure drop, good mass and heat transfer, and easy plasticity, and can be used in gas masks for CO protection.

[0056] Comparative Example 1

[0057] The difference from Example 1 is that the steam-assisted treatment step is omitted. The rest is the same as Example 1, and the prepared catalyst is recorded as Pt / Mn / γ-Al2O3 / Al-0L.

[0058] Comparative Example 2

[0059] The difference from Example 1 is that the water vapor treatment volume is 6 L, and the other conditions are the same as Example 1. The prepared modified platinum-based catalyst is recorded as Pt / Mn / γ-Al2O3 / Al-6L.

[0060] Comparative Example 3

[0061] The steps for preparing the Mn / γ-Al2O3 / Al catalyst from the γ-Al2O3 support in Comparative Example 1 were replaced by placing the obtained γ-Al2O3 support in a 1 mol / L aqueous solution of cerium nitrate hexahydrate at 25°C for 12 hours, drying it, and calcining it at 500°C for 4 hours to obtain a Ce / γ-Al2O3 / Al catalyst. The remaining steps were the same as those in Comparative Example 1, and the resulting catalyst was designated Pt / Ce / γ-Al2O3 / Al-0L.

[0062] Comparative Example 4

[0063] The steps for preparing the Mn / γ-Al2O3 / Al catalyst from the γ-Al2O3 support in Comparative Example 1 were replaced by: immersing the obtained γ-Al2O3 support in a 0.5 mol / L aqueous solution of cobalt nitrate hexahydrate at 25°C for 12 hours, drying, and calcining at 500°C for 4 hours to obtain a Co / γ-Al2O3 / Al catalyst. The remaining steps were the same as those in Comparative Example 1, and the resulting catalyst was designated Pt / Co / γ-Al2O3 / Al-0L.

[0064] Comparative Example 5

[0065] The steps for preparing the Mn / γ-Al2O3 / Al catalyst from the γ-Al2O3 support in Comparative Example 1 were replaced by: immersing the obtained γ-Al2O3 support in a 0.25 mol / L aqueous solution of copper nitrate trihydrate at 25°C for 12 hours, drying, and calcining at 500°C for 4 hours to obtain a Cu / γ-Al2O3 / Al catalyst. The remaining steps were the same as those in Comparative Example 1, and the resulting catalyst was designated Pt / Cu / γ-Al2O3 / Al-0L.

[0066] Comparative Example 6

[0067] The steps for preparing the Mn / γ-Al2O3 / Al catalyst from the γ-Al2O3 support in Comparative Example 1 were replaced by: immersing the obtained γ-Al2O3 support in a 0.1 mol / L aqueous solution of potassium titanium oxalate dihydrate at 25°C for 12 hours, drying, and calcining at 500°C for 4 hours to obtain a Ti / γ-Al2O3 / Al catalyst. The remaining steps were the same as those in Comparative Example 1, and the resulting catalyst was designated Pt / Ti / γ-Al2O3 / Al-0L.

[0068] Comparative Example 7

[0069] The difference from Comparative Example 1 is that the platinum loading step is omitted. Other procedures are the same as Comparative Example 1, and the prepared catalyst is recorded as Mn / γ-Al2O3 / Al-0L.

[0070] Comparative Example 8

[0071] The difference from Comparative Example 1 is that the manganese loading step is omitted. Other procedures are the same as Comparative Example 1, and the obtained catalyst is recorded as Pt / γ-Al2O3 / Al-0L.

[0072] Comparative Example 9

[0073] The difference from Example 1 is that the platinum loading step is omitted. Other processes are the same as Example 1. The prepared catalyst is denoted as Mn / γ-Al2O3 / Al-0.9L.

[0074] Comparative Example 10

[0075] The difference from Example 2 is that the platinum loading step is omitted. The rest is the same as Example 2, and the prepared catalyst is recorded as Mn / γ-Al2O3 / Al-1.8L.

[0076] Comparative Example 11

[0077] The difference from Example 3 is that the platinum loading step is omitted. The rest is the same as Example 3, and the prepared catalyst is recorded as Mn / γ-Al2O3 / Al-3L.

[0078] Comparative Example 12

[0079] The difference from Comparative Example 2 is that the platinum loading step is omitted. Other procedures are the same as Comparative Example 2, and the prepared catalyst is recorded as Mn / γ-Al2O3 / Al-6L.

[0080] Comparative Example 13

[0081] The difference from Example 1 is that the manganese loading step is omitted. Other processes are the same as Example 1, and the prepared catalyst is denoted as Pt / γ-Al2O3 / Al-0.9L.

[0082] Comparative Example 14

[0083] The difference from Example 2 is that the manganese loading step is omitted. Other procedures are the same as Example 2, and the prepared catalyst is denoted as Pt / γ-Al2O3 / Al-1.8L.

[0084] Comparative Example 15

[0085] The difference from Example 3 is that the manganese loading step is omitted. Other procedures are the same as Example 3, and the prepared catalyst is denoted as Pt / γ-Al2O3 / Al-3L.

[0086] Comparative Example 16

[0087] The difference from Comparative Example 2 is that the manganese loading step is omitted. Other procedures are the same as Comparative Example 2, and the prepared catalyst is recorded as Pt / γ-Al2O3 / Al-6L.

[0088] Comparative Example 17

[0089] The difference from Comparative Example 6 is that the Pt / Ti / γ-Al2O3 / Al catalyst prepared in Comparative Example 5 was subjected to a water vapor-assisted treatment. Specifically, air at a flow rate of 30 mL / min was passed through a scrubber filled with deionized water to treat the Pt / Ti / γ-Al2O3 / Al catalyst. The water vapor treatment volume was 0.9 L. All other conditions were the same as in Comparative Example 6, and the resulting catalyst was designated Pt / Ti / γ-Al2O3 / Al-0.9L.

[0090] Comparative Example 18

[0091] The difference from Comparative Example 17 is that the water vapor treatment volume is 1.8 L, and the other conditions are the same as Comparative Example 17. The prepared catalyst is recorded as Pt / Ti / γ-Al2O3 / Al-1.8L.

[0092] Comparative Example 19

[0093] The difference from Comparative Example 17 is that the water vapor treatment volume is 3L, and the other conditions are the same as Comparative Example 17. The prepared catalyst is recorded as Pt / Ti / γ-Al2O3 / Al-3L.

[0094] Comparative Example 20

[0095] The difference from Comparative Example 17 is that the water vapor treatment volume is 6L, and the other conditions are the same as Comparative Example 17. The prepared catalyst is recorded as Pt / Ti / γ-Al2O3 / Al-6L.

[0096] Figure 1 This is a flow chart for preparing a modified platinum-based catalyst for room-temperature catalytic oxidation of CO according to an embodiment of the present invention;

[0097] Figure 3The cross-sectional FESEM images of the catalysts prepared in Comparative Example 1 (a), Example 2 (b), Example 3 (c) and Comparative Example 2 (d) at different magnifications are shown. Figure 3 As can be seen, the untreated Pt / Mn / γ-Al2O3 / Al-0L catalyst in Comparative Example 1(a) exhibits a variable three-dimensional structure, with a uniform surface of upright flaky deposits. The catalyst in Optimal Example 2(b) features an upper layer of blades arranged upright, with the blades flipped out and covering the catalyst, resulting in a rougher surface and a higher specific surface area. In Example 3(c) and Comparative Example 2(d), the number of accumulated blades increases with increasing vapor-assisted treatment volume, and at 6L of vapor-assisted treatment volume, numerous stacked agglomerates appear on the surface.

[0098] Test of catalyst's ability to catalyze CO oxidation at room temperature:

[0099] The catalysts obtained in the above examples and comparative examples were processed as follows: cut into 2×2 mm 2 Weigh 0.58g of catalyst and mix it with quartz sand thoroughly, fill it into the middle of the quartz tube, and fill both ends with about 10cm of quartz sand. During the test, the temperature was room temperature 25℃, the CO concentration was 1000ppm, the CO flow rate was 100mL / min, and the total gas hourly space velocity was 26000mL / (g cat h), after the gas flow stabilizes, the reaction products are analyzed by gas chromatography. The specific process and the equipment used in the analysis process are as follows: Figure 2 The analysis results are shown in Figures 4 to 9 shown.

[0100] Figure 4 The CO conversion rate results of the catalysts prepared in Comparative Example 1, Example 1, Example 2, Example 3 and Comparative Example 2 at 25°C are shown in Figure 1; a is the CO conversion rate result diagram, and b is the CO average conversion rate result diagram; in b, fresh represents Comparative Example 1, H-0.9L represents Example 1, H-1.8L represents Example 2, H-3L represents Example 3, and H-6L represents Example 4. Figure 4 As can be seen, with increasing steam-assisted treatment volume, the catalytic performance of the catalyst first increases and then decreases. At a steam-assisted treatment volume of 1.8 L, the conversion rate reaches a maximum of 100%. This is primarily due to the fact that water vapor can modulate the hydroxyl groups on the catalyst surface. The -OH group content is highest at a steam-assisted treatment volume of 1.8 L. Activity begins to decrease with increasing steam-assisted treatment time. This is because the hydroxyl sites on the catalyst surface are occupied by undissociated water, and surface agglomeration reduces the specific surface area, thereby reducing the CO conversion rate.

[0101] Figure 5 This is the lifespan of the catalyst prepared in Example 2 for CO catalysis at room temperature (25°C). Figure 5It can be seen that under the conditions of CO concentration of 1000 ppm and CO flow rate of 100 mL / min, the catalyst life is as long as 190 h (the catalyst can achieve complete CO conversion within 190 h).

[0102] Figure 6 The figure shows the CO conversion rate of the catalysts prepared in Comparative Example 1, Comparative Example 3, Comparative Example 4, Comparative Example 5 and Comparative Example 6 at 25°C. Figure 6 The manganese-modified Pt / Mn / γ-Al2O3 / Al-0h catalyst, whose active component is the precious metal platinum, exhibits higher CO oxidation activity than the Pt / Ce / γ-Al2O3 / Al-0h, Pt / Co / γ-Al2O3 / Al-0h, Pt / Cu / γ-Al2O3 / Al-0h, and Pt / Ti / γ-Al2O3 / Al-0h catalysts. This suggests that transition metal manganese can better cooperate with platinum-based catalysts to achieve room-temperature catalytic CO oxidation. Manganese doping increases the number of water-decomposed hydroxyl groups on the platinum-based catalyst surface, which participates in the reaction and promotes the conversion of the intermediate formate, thereby lowering the reaction energy barrier.

[0103] Figure 7 The CO conversion rate results of the catalysts prepared in Comparative Examples 7, 9, 10, 11 and 12 at 25°C are shown in Figure 1; wherein, a is the CO conversion rate result diagram, and b is the CO average conversion rate result diagram; in b, fresh represents Comparative Example 6, H-0.9L represents Comparative Example 8, H-1.8L represents Comparative Example 9, H-3L represents Comparative Example 10, and H-6L represents Comparative Example 11. Figure 7 It can be seen that the ability of Mn / γ-Al2O3 / Al series catalysts to catalytically oxidize CO at room temperature is low before and after water vapor assisted treatment, and the conversion rate is less than 10%. This shows that the loading of platinum provides active sites for the catalytic oxidation of CO, and the active sites are composed of hydroxyl-modified platinum nanoparticles and Pt 0 The active structure of Pt(OH) combined with metal Pt promotes CO adsorption and O2 activation, thereby promoting the CO oxidation reaction.

[0104] Figure 8 The CO conversion rate results of the catalysts prepared in Comparative Examples 8, 13, 14, 15 and 16 at 25°C are shown in Figure 1; wherein, a is the CO conversion rate result diagram, and b is the CO average conversion rate result diagram; in b, fresh represents Comparative Example 7, H-0.9L represents Comparative Example 12, H-1.8L represents Comparative Example 13, H-3L represents Comparative Example 14, and H-6L represents Comparative Example 15. Figure 8It can be seen that the Pt / γ-Al2O3 / Al series catalysts, whose active component is precious platinum and have not been modified with manganese, have the highest catalytic efficiency without steam-assisted treatment. However, the catalytic efficiency decreases after 0.9L, 1.8L, 3L, and 6L of steam-assisted treatment. The main reason is that steam-assisted treatment of the Pt / γ-Al2O3 / Al series catalysts does not increase the amount of adsorbed water and hydroxyl groups, and thus cannot improve the room-temperature catalytic oxidation activity of CO.

[0105] Figure 9 The CO conversion rate results of the catalysts prepared in Comparative Examples 6, 17, 18, 19 and 20 at 25°C are shown in Figure 1; wherein, a is the CO conversion rate result diagram, and b is the CO average conversion rate result diagram; in b, fresh represents Comparative Example 5, H-0.9L represents Comparative Example 16, H-1.8L represents Comparative Example 17, H-3L represents Comparative Example 18, and H-6L represents Comparative Example 19. Figure 9 It can be seen that the catalytic efficiency of the Pt / Ti / γ-Al2O3 / Al series catalysts modified with titanium, whose active component is precious metal platinum, after water vapor-assisted treatment for 0.9L, 1.8L, 3L and 6L was lower than that of the catalyst without water vapor treatment, indicating that water vapor-assisted treatment would reduce the room-temperature catalytic oxidation activity of Pt / Ti / γ-Al2O3 / Al series catalysts for CO.

[0106] analyze Figures 7-9 The data show that manganese modification and water vapor-assisted treatment have a synergistic promoting effect on the catalytic oxidation of CO over platinum-based catalysts at room temperature.

[0107] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0108] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing a modified platinum-based catalyst for room-temperature catalytic oxidation of CO suitable for a CO protection gas mask, characterized in that: The steps include: An aluminum-based support is modified using a manganese metal compound solution to obtain a manganese-modified aluminum-based support; platinum is loaded on the manganese-modified aluminum-based support to obtain a platinum-loaded manganese-modified aluminum-based support; and the platinum-loaded manganese-modified aluminum-based support is subjected to a water vapor-assisted treatment to obtain the modified platinum-based catalyst for room-temperature catalytic oxidation of CO; The manganese metal compound solution includes a manganese source and a urea solution; In the manganese metal compound solution, the concentration of the manganese source is 0.01 to 0.05 mol / L, and the concentration of urea is 0.1 to 0.6 mol / L; the manganese source includes one or more of manganese sulfate, manganese acetate tetrahydrate, manganese nitrate, and potassium permanganate; The modification step comprises: impregnating the aluminum-based support in a manganese metal compound solution, and then calcining the aluminum-based support; the temperature for impregnating the aluminum-based support in the manganese metal compound solution is 50 to 95° C., and the time for impregnation in the manganese metal compound solution is 8 to 16 hours; the temperature for calcining the aluminum-based support is 350 to 500° C., and the time for calcining the aluminum-based support is 2 to 5 hours; The water vapor-assisted treatment step includes: using air at a certain flow rate to treat the platinum-loaded manganese-modified aluminum-based carrier through a container filled with water; the air flow rate is 20 to 50 mL / min; the water vapor-assisted treatment volume is 0 to 3 L, excluding 0 L; water vapor-assisted treatment volume = air flow rate × time.

2. The preparation method according to claim 1, characterized in that The step of loading platinum on a manganese-modified aluminum-based carrier comprises: placing the manganese-modified aluminum-based carrier in a platinum-containing solution for immersion, and then chemically reducing it; the concentration of the platinum compound in the platinum-containing solution is 0.05 to 1.25 g / L; the immersion temperature is 50 to 95° C., and the immersion time is 1 to 6 hours.

3. The preparation method according to claim 2, characterized in that The platinum compound in the platinum-containing solution includes chloroplatinic acid, tetraammineplatinum hydroxide hydrate or tetraammineplatinum chloride hydrate.

4. The preparation method according to claim 2, characterized in that The chemical reduction step comprises: placing the impregnated product in a sodium borohydride solution for reduction; the concentration of the sodium borohydride solution is 1 to 3 g / L; the reduction temperature is 20 to 45° C., and the reduction time is 1 to 12 hours.

5. The preparation method according to claim 1, characterized in that The preparation steps of the aluminum-based support are as follows: the aluminum substrate is anodized and then subjected to a first calcination, a hot water hydration reaction, and a second calcination in sequence to obtain the aluminum-based support; the aluminum substrate comprises an aluminum mesh; the anodization conditions are: the electrolyte is an oxalic acid solution, the temperature is 15-35°C, and the current density is 20-35A / m 2 , time is 4 to 16 hours; the temperature of the first calcination and the second calcination is independently 350 to 550°C; the time of the first calcination is 1 to 5 hours; the time of the second calcination is 3 to 6 hours; the temperature of the hot water hydration reaction is 30 to 95°C, and the time of the hot water hydration reaction is 60 to 120 minutes.

6. A modified platinum-based catalyst for room-temperature catalytic oxidation of CO prepared by the preparation method according to any one of claims 1 to 5.

7. Use of the modified platinum-based catalyst for room-temperature catalytic oxidation of CO according to claim 6 in room-temperature catalytic oxidation of CO.

8. A method for catalytic oxidation of CO at room temperature, characterized in that: The modified platinum-based catalyst according to claim 6 is used as a catalyst for the catalytic oxidation of CO at room temperature.

Images