Modified platinum-based catalyst for CO normal-temperature catalytic oxidation as well as preparation method and application of modified platinum-based catalyst

Abstract

The invention discloses a modified platinum-based catalyst for CO normal-temperature catalytic oxidation and a preparation method and application thereof, and belongs to the technical field of catalysts. The preparation method of the modified platinum-based catalyst comprises the following steps: modifying an aluminum-based carrier by 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 carrying out water vapor auxiliary treatment on the platinum-loaded manganese modified aluminum-based carrier to obtain the modified platinum-based catalyst for CO normal-temperature catalytic oxidation, the manganese metal compound solution comprises a manganese source and a urea solution. The catalyst is simple in preparation process and can be industrially produced in batches. The catalyst can be used for CO catalytic oxidation at normal temperature, the catalytic life is as long as 190 hours, a solution is provided for CO removal at normal temperature, and possibility is provided for wide application of gas masks.

Description

Technical Field

[0001] The present invention belongs to the technical field of catalysts, and more specifically 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 places not only cause property losses 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 be poisoned and die in fires. CO is a colorless, odorless, suffocating toxic gas. CO can bind to hemoglobin in human red blood cells, reducing the oxygen delivery capacity. The symptoms and signs of CO poisoning are related to the carboxyhemoglobin saturation (COHb%) in the blood. The COHb% of most people who die from CO poisoning in fires is 50-70%. Equipped with firefighting equipment such as gas masks that can remove CO toxic gases in fires, homes can be self-rescued in time to reduce life safety losses. 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 in cost, their service life is only 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 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 purpose of the present invention is to provide a modified platinum-based catalyst for catalytic oxidation of CO at room temperature and a preparation method and application thereof, so as to solve the problems that the existing platinum-based catalyst has low activity at ambient temperature and humidity, and the catalyst morphology causes it to be unable to be used in gas masks for CO protection.

[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] The aluminum-based carrier is modified by a manganese metal compound solution to obtain a manganese-modified aluminum-based carrier; platinum is loaded on the manganese-modified aluminum-based carrier to obtain a platinum-loaded manganese-modified aluminum-based carrier; the platinum-loaded manganese-modified aluminum-based carrier is subjected to water vapor-assisted treatment to obtain the modified platinum-based catalyst for catalytic oxidation of CO at room temperature;

[0008] The present invention reduces the activation energy of the CO reaction on the catalyst surface by doping with transition metal manganese, and promotes the CO catalytic oxidation reaction to be more likely 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 activity of the catalyst in catalytic oxidation of CO at room temperature. In addition, by performing water vapor-assisted treatment on the catalyst, the catalyst has a suitable amount of hydroxyl. Through the water vapor-assisted treatment, the physically adsorbed water and -OH on the catalyst surface are increased, and the physically adsorbed water molecules on the MnO 2 Surface dissociation produces a large amount of -OH, which plays an important role in catalytic oxidation, especially in the catalytic reaction with "CO+-OH" as the reaction path, thereby improving the catalytic activity of the catalyst. Manganese is used as the modified material, platinum is used as the doped precious metal, and water vapor-assisted treatment is used to produce more hydroxyl active groups on the catalyst surface;

[0009] In the preparation process of the aluminum-based carrier, the porous anodized aluminum substrate is first calcined to obtain the porous anodized AAO; the hydroxyl-rich boehmite (AlOOH) is obtained by hot hydration reaction; and the aluminum-based carrier (γ-Al) with a dense and ordered porous structure is obtained by the second calcination. 2 O 3 carrier). 2 O 3 The aluminum-based support can optimize the active sites for CO catalytic oxidation. 2 O 3 Surface Al 3+ Site binding, which makes these sites coordination saturated (pentahedral to octahedral conversion), thus optimizing the active site;

[0010] The manganese metal compound solution includes a manganese source and a urea solution; urea is selected to undergo a redox 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 0.01-0.06 mol / L, and the concentration of urea is 0.2-0.8 mol / L; the manganese source includes one or more of manganese sulfate, manganese acetate tetrahydrate, manganese nitrate and potassium permanganate; the modification step includes: impregnating the aluminum-based carrier in the manganese metal compound solution, and then roasting; the temperature for impregnating the aluminum-based carrier in the manganese metal compound solution is 50-95°C, and the time for impregnation in the manganese metal compound solution is 8-16 hours; the temperature for roasting is 350-500°C, and the time for roasting is 2-5 hours.

[0012] Preferably, the step of loading platinum on the manganese-modified aluminum-based carrier comprises: impregnating the manganese-modified aluminum-based carrier in a platinum-containing solution and then reducing it chemically; 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 product obtained after the impregnation 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 selects sodium borohydride solution for reduction. Sodium borohydride generates a large amount of hydrogen during the reduction process, resulting in bubbles and local solution disturbance. This gas release can promote the generation of manganese nanoparticles or nanosheets, resulting in increased surface roughness. Moreover, during the reduction reaction, rapid gas release can cause holes on the surface of the material, thereby forming a porous structure. The porous structure increases the specific surface area of ​​the material and significantly changes its surface morphology.

[0016] Preferably, the preparation steps of the aluminum-based carrier 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 carrier; the aluminum substrate comprises an aluminum mesh; the conditions of the anodization are: the electrolyte is an oxalic acid solution, the temperature is 15 to 35°C, and the current density is 20 to 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 step of water vapor assisted treatment 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 20-50 mL / min; the water vapor assisted treatment volume is 0-3 L, excluding 0 L; water vapor assisted treatment volume = air flow rate × time.

[0019] The second technical solution of the present invention: providing 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 loading amount of manganese is 4 to 6 wt%, and the loading amount of platinum is 1 to 3 wt%.

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

[0022] Technical solution 4 of the present invention: provides 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, and promotes the CO catalytic oxidation reaction to occur more easily; and, by modifying the transition metal manganese, the water dissociation energy on the catalyst surface is greatly reduced, and the surface is prompted 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 has a suitable amount of hydroxyl. The catalyst has achieved a 26000mL / (g cat h), the CO conversion rate of 0.58g of the modified platinum-based catalyst for room-temperature catalytic oxidation of CO at 25°C reached 100%. The development of the structured modified platinum-based catalyst for room-temperature catalytic oxidation of CO provides a solution for room-temperature CO removal and makes possible the widespread application 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 can be industrially mass-produced. Moreover, the catalyst can realize catalytic oxidation of CO at room temperature, solving the problem that the catalyst currently used for catalytic oxidation of CO needs to be catalyzed at high temperature when catalyzing the 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 catalytic oxidation of CO at room temperature and has excellent room-temperature catalytic stability. BRIEF DESCRIPTION OF THE DRAWINGS

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

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

[0029] Figure 3 The 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 The CO conversion rate results of the catalysts prepared in Comparative Example 1, Example 1, Example 2, Example 3 and Example 4 at 25°C are shown in Figure 1; wherein a is a CO conversion rate result diagram, and b is a 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;

[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 result graphs of the catalysts prepared in Comparative Example 6, Comparative Example 8, Comparative Example 9, Comparative Example 10 and Comparative Example 11 at 25°C; 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 rate result graphs of the catalysts prepared in Comparative Example 7, Comparative Example 12, Comparative Example 13, Comparative Example 14 and Comparative Example 15 at 25°C; 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 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] Fig. 9 The CO conversion rate result graphs of the catalysts prepared in Comparative Example 5, Comparative Example 16, Comparative Example 17, Comparative Example 18 and Comparative Example 19 at 25°C; 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 should be understood as a more detailed description of certain aspects, features, and embodiments of the present invention.

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

[0038] Unless otherwise indicated, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art. Although the present invention describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation 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 a conflict with any incorporated document, the content 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 of the present invention description without departing from the scope or spirit of the present invention. Other embodiments derived from the present invention description will be apparent to those skilled in the art. The present invention description and examples are exemplary 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 (purchased from the market, any product of the same existing technology) to a concentration of 3-6wt% and soak the aluminum mesh at room temperature for 10 minutes. Place it in an anodizing tank at 20°C and place it at a current density of 25A / m 2 After being anodized in 0.3 mol / L oxalic acid solution for 8 hours, the γ-Al was obtained by rinsing with deionized water and drying naturally, calcining at 450°C for 1 hour, hydrating in deionized water at 70°C for 60 minutes, and drying at room temperature. 2 O 3 carrier.

[0046] The obtained γ-Al 2 O 3 The carrier was placed in a mixed solution 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 Mn / γ-Al 2 O 3 / Al catalyst.

[0047] Mn / γ-Al 2 O 3 The / 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 noble metal catalyst, recorded as Pt / Mn / γ-Al 2 O 3 / Al.

[0048] The Pt / Mn / γ-Al2O3 was subjected to a 30 mL / min air flow through a gas washing bottle filled with deionized water at room temperature (25°C). 2 O 3 / Al was treated with water vapor, and the water vapor treatment volume was 0.9L to obtain a modified platinum-based catalyst, which was recorded as Pt / Mn / γ-Al 2 O 3 / Al-0.9L.

[0049] The modified platinum-based catalyst obtained in this example is a structured mesh, 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 other parameters are the same as those in Example 1. The prepared modified platinum-based catalyst is denoted as Pt / Mn / γ-Al 2 O 3 / Al-1.8L.

[0052] The modified platinum-based catalyst obtained in this example is a structured mesh, 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 3L, and the other parts are the same as Example 1. The prepared modified platinum-based catalyst is recorded as Pt / Mn / γ-Al 2 O 3 / Al-3L.

[0055] The modified platinum-based catalyst obtained in this example is a structured mesh, 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 water vapor auxiliary treatment step is omitted. The other steps are the same as Example 1. The prepared catalyst is denoted as Pt / Mn / γ-Al 2 O 3 / Al-0L.

[0058] Comparative Example 2

[0059] The difference from Example 1 is that the water vapor treatment volume is 6L, and the other parts are the same as Example 1. The prepared modified platinum-based catalyst is recorded as Pt / Mn / γ-Al 2 O 3 / Al-6L.

[0060] Comparative Example 3

[0061] In Comparative Example 1, γ-Al 2 O 3 Support preparation of Mn / γ-Al 2 O 3 / Al catalyst step is replaced by: 2 O 3 The support was placed in an aqueous solution of cerium nitrate hexahydrate with a concentration of 1 mol / L, immersed at 25°C for 12 h, dried and calcined at 500°C for 4 h to obtain Ce / γ-Al 2 O 3The same as in Comparative Example 1, the catalyst obtained is denoted as Pt / Ce / γ-Al 2 O 3 / Al-0L.

[0062] Comparative Example 4

[0063] In Comparative Example 1, γ-Al 2 O 3 Support preparation of Mn / γ-Al 2 O 3 / Al catalyst step is replaced by: 2 O 3 The carrier was placed in an aqueous solution of cobalt nitrate hexahydrate with a concentration of 0.5 mol / L, immersed at 25°C for 12 h, dried and calcined at 500°C for 4 h to obtain Co / γ-Al 2 O 3 The same as in Comparative Example 1, the catalyst obtained is denoted as Pt / Co / γ-Al 2 O 3 / Al-0L.

[0064] Comparative Example 5

[0065] In Comparative Example 1, γ-Al 2 O 3 Support preparation of Mn / γ-Al 2 O 3 / Al catalyst step is replaced by: 2 O 3 The support was placed in an aqueous solution of copper nitrate trihydrate with a concentration of 0.25 mol / L, immersed at 25 °C for 12 h, dried and calcined at 500 °C for 4 h to obtain Cu / γ-Al 2 O 3 The same as in Comparative Example 1, the catalyst prepared is denoted as Pt / Cu / γ-Al 2 O 3 / Al-0L.

[0066] Comparative Example 6

[0067] In Comparative Example 1, γ-Al 2 O 3 Support preparation of Mn / γ-Al 2 O 3 / Al catalyst step is replaced by: 2 O 3 The support was placed in an aqueous solution of potassium titanium oxalate dihydrate with a concentration of 0.1 mol / L, immersed at 25°C for 12 h, dried and calcined at 500°C for 4 h to obtain Ti / γ-Al2 O 3 The same as in Comparative Example 1, the catalyst prepared is denoted as Pt / Ti / γ-Al 2 O 3 / Al-0L.

[0068] Comparative Example 7

[0069] The difference from Comparative Example 1 is that the platinum loading step is omitted. The other steps are the same as those in Comparative Example 1. The obtained catalyst is denoted as Mn / γ-Al 2 O 3 / Al-0L.

[0070] Comparative Example 8

[0071] The difference from Comparative Example 1 is that the step of manganese loading is omitted. The other steps are the same as those in Comparative Example 1. The obtained catalyst is denoted as Pt / γ-Al 2 O 3 / Al-0L.

[0072] Comparative Example 9

[0073] The difference from Example 1 is that the platinum loading step is omitted. The other steps are the same as Example 1. The obtained catalyst is denoted as Mn / γ-Al 2 O 3 / Al-0.9L.

[0074] Comparative Example 10

[0075] The difference from Example 2 is that the platinum loading step is omitted. The other steps are the same as Example 2. The obtained catalyst is recorded as Mn / γ-Al 2 O 3 / Al-1.8L.

[0076] Comparative Example 11

[0077] The difference from Example 3 is that the platinum loading step is omitted. The other steps are the same as Example 3. The obtained catalyst is recorded as Mn / γ-Al 2 O 3 / Al-3L.

[0078] Comparative Example 12

[0079] The difference from Comparative Example 2 is that the platinum loading step is omitted. The other steps are the same as those in Comparative Example 2. The obtained catalyst is denoted as Mn / γ-Al 2 O 3 / Al-6L.

[0080] Comparative Example 13

[0081] The difference from Example 1 is that the step of manganese loading is omitted. The other steps are the same as Example 1. The obtained catalyst is denoted as Pt / γ-Al 2O 3 / Al-0.9L.

[0082] Comparative Example 14

[0083] The difference from Example 2 is that the step of manganese loading is omitted. The other steps are the same as Example 2. The obtained catalyst is denoted as Pt / γ-Al 2 O 3 / Al-1.8L.

[0084] Comparative Example 15

[0085] The difference from Example 3 is that the step of manganese loading is omitted. The other steps are the same as those in Example 3. The obtained catalyst is denoted as Pt / γ-Al 2 O 3 / Al-3L.

[0086] Comparative Example 16

[0087] The difference from Comparative Example 2 is that the step of manganese loading is omitted. The other steps are the same as those in Comparative Example 2. The obtained catalyst is denoted as Pt / γ-Al 2 O 3 / Al-6L.

[0088] Comparative Example 17

[0089] The difference from Comparative Example 6 is that the Pt / Ti / γ-Al prepared in Comparative Example 5 2 O 3 The Pt / Ti / γ-Al catalyst was treated with water vapor. Specifically, air with a flow rate of 30 mL / min was passed through a gas washing bottle filled with deionized water to 2 O 3 The catalyst was treated with water vapor, and the water vapor treatment volume was 0.9 L. The other catalysts were the same as those in Comparative Example 6, and the catalyst was recorded as Pt / Ti / γ-Al 2 O 3 / Al-0.9L.

[0090] Comparative Example 18

[0091] The difference from Comparative Example 17 is that the water vapor treatment volume is 1.8L, and the other conditions are the same as those of Comparative Example 17. The prepared catalyst is denoted as Pt / Ti / γ-Al 2 O 3 / 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 those of Comparative Example 17. The prepared catalyst is denoted as Pt / Ti / γ-Al 2 O 3 / 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 those of Comparative Example 17. The prepared catalyst is denoted as Pt / Ti / γ-Al 2 O 3 / Al-6L.

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

[0097] Figure 3 The 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 It can be seen that the Pt / Mn / γ-Al in Comparative Example 1(a) without water vapor assisted treatment 2 O 3 / Al-0L catalyst has a variable three-dimensional structure, and the surface presents a uniform vertical sheet stacking. The catalyst of the best embodiment 2(b) has blades on the upper layer turned out and covered in vertical arrangement, and the catalyst surface is rougher and has a higher specific surface area. In embodiment 3(c) and comparative example 2(d), as the water vapor assisted treatment amount increases, the number of stacked blades increases, and when the water vapor assisted treatment amount is 6L, a large number of stacked agglomerations appear on the surface.

[0098] Catalyst catalytic oxidation ability test for CO 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, fill it in 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 is stabilized, the reaction product is 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 4It can be seen that with the increase of the water vapor assisted treatment amount, the catalytic performance of the catalyst first increases and then decreases. When the water vapor assisted treatment amount is 1.8L, the conversion rate is as high as 100%. The main reason is that water vapor can adjust the hydroxyl groups on the catalyst surface. The -OH group content is the highest when the water vapor assisted treatment amount is 1.8L. As the water vapor assisted treatment time increases, the activity begins to decrease. This is because the hydroxyl sites on the catalyst surface are occupied by undissociated water, and the surface agglomerates, which reduces the specific surface area, so the CO conversion rate decreases.

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

[0102] Figure 6 The results of the CO conversion rate of the catalysts prepared in Comparative Examples 1, 3, 4, 5 and 6 at 25°C are shown in FIG. Figure 6 It can be seen that the active component is the precious metal platinum, and the catalyst Pt / Mn / γ-Al 2 O 3 / Al-0h has higher catalytic activity for CO oxidation than Pt / Ce / γ-Al 2 O 3 / Al-0h catalyst, Pt / Co / γ-Al 2 O 3 / Al-0h catalyst, Pt / Cu / γ-Al 2 O 3 / Al-0h catalyst and Pt / Ti / γ-Al 2 O 3 / Al-0h catalyst. This indicates that transition metal manganese can better cooperate with platinum-based catalysts to achieve room-temperature catalytic oxidation of CO. Through manganese doping, more water on the surface of the platinum-based catalyst decomposes to produce hydroxyl groups to participate in the reaction, which promotes the conversion of the intermediate product formate and thus reduces the energy barrier of the reaction.

[0103] Figure 7 The results of CO conversion at 25°C for the catalysts prepared in Comparative Examples 7, 9, 10, 11 and 12 are shown in Figure 1; a is the CO conversion result, and b is the CO average conversion result; 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 Mn / γ-Al 2 O 3The ability of the / Al series catalysts to catalytically oxidize CO at room temperature was low before and after water vapor-assisted treatment, and the conversion rate was less than 10%. This indicates 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 O 2 activation, thereby promoting the oxidation reaction of CO.

[0104] Figure 8 The results of the CO conversion rates 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 8 It can be seen that the active component is precious metal platinum, and the Pt / γ-Al 2 O 3 The catalytic efficiency of the Pt / γ-Al series catalysts was the highest without water vapor treatment. After water vapor treatment for 0.9L, 1.8L, 3L and 6L, the catalytic efficiency decreased. The main reason is that the Pt / γ-Al 2 O 3 The water vapor-assisted treatment of the Al / Al series catalysts will not increase the amount of adsorbed water and hydroxyl groups, and thus cannot improve the room-temperature catalytic oxidation activity of CO.

[0105] Fig. 9 The results of CO conversion at 25°C for the catalysts prepared in Comparative Examples 6, 17, 18, 19 and 20 are shown in Figure 1; a is the CO conversion result, and b is the CO average conversion result; 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. Fig. 9 It can be seen that the active component is precious metal platinum, and the titanium-modified Pt / Ti / γ-Al 2 O 3 The catalytic efficiency of the Pt / Ti / γ-Al series catalysts after 0.9L, 1.8L, 3L and 6L water vapor assisted treatment was lower than that of the catalysts without water vapor treatment, indicating that water vapor assisted treatment would reduce the 2 O 3 / Al series catalysts for room temperature catalytic oxidation of CO.

[0106] analyze Figures 7 to 9The data show that manganese modification and water vapor-assisted treatment have a synergistic 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 enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be 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 will not be limited to the embodiments shown herein, but rather 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 catalytic oxidation of CO at room temperature, characterized in that: The steps include: The aluminum-based carrier is modified by a manganese metal compound solution to obtain a manganese-modified aluminum-based carrier; platinum is loaded on the manganese-modified aluminum-based carrier to obtain a platinum-loaded manganese-modified aluminum-based carrier; the platinum-loaded manganese-modified aluminum-based carrier is subjected to water vapor-assisted treatment to obtain the modified platinum-based catalyst for catalytic oxidation of CO at room temperature; The manganese metal compound solution includes a manganese source and a urea solution.

2. The preparation method according to claim 1, characterized in that: In the manganese metal compound solution, the concentration of the manganese source is 0.01-0.05 mol / L, and the concentration of urea is 0.1-0.6 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 carrier in a manganese metal compound solution, and then calcining; The aluminum-based carrier is impregnated in the manganese metal compound solution at a temperature of 50 to 95° C. and for a time of 8 to 16 hours; the calcination temperature is 350 to 500° C. and for a time of 2 to 5 hours.

3. 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 reducing it chemically; 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.

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

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

6. The preparation method according to claim 1, characterized in that: The preparation steps of the aluminum-based carrier are as follows: the aluminum substrate is subjected to anodization and then subjected to a first calcination, a hot water hydration reaction and a second calcination in sequence to obtain the aluminum-based carrier; the aluminum substrate comprises an aluminum mesh; the conditions of the anodization are: the electrolyte is an oxalic acid solution, the temperature is 15 to 35° C., and the current density is 20 to 35 A / 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.

7. The preparation method according to claim 1, characterized in that: The step of water vapor assisted treatment includes: using air with 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 20-50mL / min; the water vapor assisted treatment volume is 0-3L, excluding 0L.

8. A modified platinum-based catalyst for catalytic oxidation of CO at room temperature prepared by the method for preparing a modified platinum-based catalyst for catalytic oxidation of CO at room temperature according to any one of claims 1 to 7.

9. Use of the modified platinum-based catalyst for room-temperature catalytic oxidation of CO as claimed in claim 8 in room-temperature catalytic oxidation of CO.

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

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