Oxygen vacancy-dislocation structure PtM alloy / γ-Al2O3 catalytic material, its preparation method, application and exhaust gas treatment device

Abstract

This invention belongs to the field of waste gas treatment, specifically relating to oxygen vacancy-dislocation structure PtM alloy / γ-Al2O3 catalytic materials, their preparation methods, applications, and tail gas treatment devices. The oxygen vacancy-dislocation structure PtM alloy / γ-Al2O3 catalytic material includes a support and its supported active components. The support is oxygen-deficient γ-Al2O3, and the active components are PtM nano-alloy particles with dislocation structures. In PtM, M includes at least one of Pd, Cu, Co, and Mn; the mass ratio of Pt to M is 1~4:1; and the content of the active components is 0.1~5 wt.%. This invention provides an oxygen vacancy-dislocation structure PtM alloy / γ-Al2O3 catalytic material that, based on the combined control of composition and physicochemical structure, achieves synergy, exhibiting excellent low-temperature activity, as well as excellent high-temperature stability and selectivity.

Description

Technical Field

[0001] This invention belongs to the field of gaseous pollutant treatment, specifically relating to automotive exhaust treatment materials. Background Technology

[0002] Diesel vehicles have a broad market prospect due to their advantages such as high fuel efficiency, economy, durability, and high safety. However, diesel vehicle exhaust contains carbon monoxide (CO) and nitrogen oxides (NOx). x The content of diesel fuel and hydrocarbons (HC) in diesel vehicles is much higher than that in gasoline vehicles, posing a great threat to the ecological environment and human health. Therefore, effectively controlling diesel vehicle pollution emissions is of great significance for their market promotion and application.

[0003] For diesel vehicle exhaust treatment, the main existing approaches include oxidation, adsorption, and reduction. The oxidation approach converts carbon monoxide (CO) and hydrocarbons (HC) into carbon dioxide and water through oxidation reactions; its primary catalytic material is a supported platinum group metal catalyst. The reduction approach removes NO from the exhaust gas. x It is reduced to nitrogen and water; common reduction catalysts include vanadium-containing and metal-based supported catalysts such as V₂O₅, WO₃, MoO₃, and TiO₂. To improve performance, existing technologies also offer several multi-effect catalyst approaches using a combination of noble and non-noble metal catalysts.

[0004] For example, US Patent Publication No. US20240009652A1 discloses a catalyst composition for the selective catalytic reduction of nitrogen oxides, which comprises at least one vanadium oxide, at least one tungsten oxide, and at least one antimony oxide. As another example, US Patent Publication No. US9403156A2 discloses a method for reducing NO in diesel exhaust. x The catalyst for emission is supported on copper ions and Al removal catalyst. +3 Zeolite containing at least one trivalent metal ion other than [other metals]. Chinese patent document CN120115183A discloses a method for preparing an adsorption-reduction bifunctional catalyst for diesel vehicle exhaust denitrification. The method involves uniformly loading Pd and Cu components onto the surface of a molecular sieve to obtain corresponding Pd and Cu-based molecular sieves; then, using solid-phase grinding, the Pd-based and Cu-based molecular sieves are coupled in a certain ratio to obtain an adsorption-reduction bifunctional Pd-Cu / SSZ-13 catalyst.

[0005] Although existing technologies have reported numerous supported catalysts that can achieve good treatment results for diesel combustion exhaust gases, there are still significant shortcomings in practical applications: First, insufficient low-temperature catalytic activity; during the cold start phase of diesel vehicles (exhaust gas temperature below 150°C), pollutants are difficult to adsorb and activate, resulting in low purification efficiency. Second, the interaction between precious metals and the support is weak, and long-term use can easily lead to the agglomeration and sintering of precious metal particles, resulting in catalyst activity decay. Third, poor selectivity for NO oxidation; the NO2 content is usually below 50%, making it difficult to meet the subsequent DPF regeneration requirements. Summary of the Invention

[0006] To address the problems existing in the prior art, the primary objective of this invention is to provide an oxygen vacancy-dislocation structure PtM alloy / γ-Al2O3 catalytic material, aiming to provide a catalyst with properties such as low-temperature start-up, high-temperature resistance, and excellent NO2 selectivity.

[0007] The second objective of this invention is to provide a PtM alloy / γ-Al2O3 catalytic material with an oxygen vacancy-dislocation structure and its application in automobile exhaust treatment.

[0008] A third objective of this invention is to provide a tail gas treatment device comprising the oxygen vacancy-dislocation structure PtM alloy / γ-Al2O3 catalytic material.

[0009] A PtM alloy / γ-Al2O3 catalytic material with an oxygen vacancy-dislocation structure includes a support and its supported active components, wherein the support is oxygen-deficient γ-Al2O3 and the active components are PtM nano-alloy particles with dislocation structures.

[0010] In PtM, M includes at least one of Pd, Cu, Co, and Mn; the mass ratio of Pt to M is 1 to 4:1.

[0011] In the oxygen vacancy-dislocation structure PtM alloy / γ-Al2O3 catalytic material, the content of active components is 0.1~5 wt.%.

[0012] This invention provides an oxygen vacancy-dislocation structure PtM alloy / γ-Al2O3 catalytic material, which, based on the combined control of composition and physicochemical structure, can achieve synergy and has excellent low-temperature activity. In addition, it also has excellent high-temperature stability and selectivity.

[0013] In this invention, the loading of γ-Al₂O₃ onto PtM alloys can theoretically enhance the catalytic purification activity of diesel vehicle exhaust. However, studies have shown that inappropriate preparation processes are unlikely to effectively improve the dispersion state and interfacial interactions between PtM alloys and γ-Al₂O₃, and cannot simultaneously construct the oxygen vacancies on the support and the defective structure of the alloy. Furthermore, existing PtM alloys are mostly regular structures without specific defects, and often suffer from limitations in the activity of a single noble metal or insufficient synergy between two metals. This invention reveals that the synergistic effect between these traditional PtM alloys and the support is weak, and their low-temperature catalytic activity and high-temperature stability need further improvement. The synergistic effect of PtM alloys in this invention is achieved through a triple coupling of dislocation structure and support oxygen vacancies: Pt optimizes the electronic state distribution of M, reducing the activation energy; the dislocation structure provides more active sites; and oxygen vacancies enhance pollutant adsorption and electron transfer.

[0014] In this invention, the mass ratio of Pt to M in the active ingredient is 1~2.5:1; and its particle size is 5~10 mm. nm.

[0015] In the oxygen vacancy-dislocation structure PtM alloy / γ-Al2O3 catalytic material, the content of active component is 0.5~2Wt.%, which can be further 1~1.5Wt.

[0016] The present invention also provides a method for preparing the oxygen vacancy-dislocation structure PtM alloy / γ-Al2O3 catalytic material, wherein γ-Al2O3 is pre-heat modified by heat treatment at 300~500℃ in an oxygen-containing atmosphere, and then subjected to rapid cooling to obtain modified γ-Al2O3.

[0017] Modified γ-Al2O3, platinum source, M source, and reducing agent were mixed in liquid phase and reduced and precipitated with the assistance of nano-microbubbles to obtain a precipitate with PtM alloy deposited on modified γ-Al2O3; the reducing agent was a water-soluble borohydride.

[0018] The precipitate was then annealed to obtain the oxygen vacancy-dislocation structure PtM alloy / γ-Al2O3 catalytic material.

[0019] The key challenge in successfully preparing the material described in this invention lies in constructing an abundant oxygen vacancy and dislocation structure. To address this challenge, this invention innovatively selects γ-Al₂O₃ as the support and performs thermal modification and rapid quenching combined modification treatments on it in an oxygen-containing atmosphere. Furthermore, a reduction precipitation scheme combining nanobubbles and water-soluble borohydrides is employed. This unexpectedly achieves synergy, inducing abundant oxygen vacancies, PtM ​​alloying, and the creation of internal dislocation structures, thus improving the interface between the active particles and the support. Research in this invention demonstrates that the preparation method can produce a unique PtM alloy / γ-Al₂O₃ catalytic material that balances oxygen vacancy and dislocation structures. Moreover, the physicochemical structure of the material prepared by this method unexpectedly exhibits excellent low-temperature activity and high-temperature stability.

[0020] In this invention, the oxygen-containing atmosphere is an atmosphere containing oxygen, wherein the oxygen content is above 5%; further, it can be air.

[0021] The temperature for thermal modification is 350~450℃; further, it is 380~420℃. Studies have shown that the preferred temperature helps to further synergistically construct the oxygen vacancy-dislocation structure catalytic material, which helps to further enhance its exhaust gas treatment effect.

[0022] The heat modification time is 1~5h; it can be further extended to 2~4h.

[0023] The cooling medium for quenching is a flowing liquid or solid with a temperature below 10°C. Examples include chilled water, liquid nitrogen, and dry ice.

[0024] In this invention, the rapid cooling treatment can be an indirect rapid cooling treatment. For example, γ-Al2O3 is thermally modified in a container, and then the container containing γ-Al2O3 is brought into direct contact with a cooling medium while it is still hot to perform rapid cooling treatment.

[0025] In this invention, the M source is a water-soluble compound of element M;

[0026] The platinum source is hydrated chloroplatinic acid;

[0027] In the initial solution system for reducing precipitation, the concentration of the platinum source is: 0.4~0.55 mmol / L;

[0028] The initial solution system for reducing the precipitation also contains a polymeric dispersant, such as at least one of polypyrrolidone. Furthermore, the concentration of the dispersant in the initial solution system is 0.6–0.7%. mg / mL;

[0029] In the initial solution system for reducing precipitation, the total weight of PtM elements is 0.1~5 wt.% of the weight of modified γ-Al2O3, and can be further 0.5~2 wt.%.

[0030] In this invention, a particle size distribution is continuously introduced into the mixed solution system of the reduction precipitation process. 50~200 nm Inert gas nanobubbles with a bubble concentration ≥10 8 cells / mL, ventilation rate 10~15 mL / min;

[0031] The reduction and precipitation time assisted by nano-microbubbles is 20~60 min.

[0032] In this invention, the atmosphere during the annealing stage is at least one of nitrogen and rare gases;

[0033] The annealing process is carried out at a temperature of 250°C. ℃~550 ℃; further, it can be 300 ℃~500 ℃; further, 350~450℃. Studies have shown that the preferred temperature helps to further synergistically construct the oxygen vacancy-dislocation structure catalytic material, and helps to further enhance its exhaust gas treatment effect.

[0034] Annealing time is 1~8 minutes. h, and further up to 3~6h.

[0035] The present invention also provides an application of the oxygen vacancy-dislocation structure PtM alloy / γ-Al2O3 catalytic material described above, using it as a catalyst for catalytic treatment of automobile exhaust.

[0036] The aforementioned application refers to diesel combustion exhaust gas.

[0037] The present invention also provides an exhaust gas treatment device, which includes an exhaust gas catalyst, wherein the exhaust gas catalyst comprises the oxygen vacancy-dislocation structure PtM alloy / γ-Al2O3 catalytic material described in the present invention.

[0038] The exhaust gas treatment device of the present invention, except for the exhaust gas catalyst described in the present invention, may have other known components and structural parts.

[0039] Beneficial effects

[0040] This invention provides an oxygen vacancy-dislocation structured PtM alloy / γ-Al2O3 catalytic material, which, based on the combined control of composition and physicochemical structure, achieves synergistic effects and exhibits excellent low-temperature activity, as well as excellent high-temperature stability. For example, the material described in this invention... It can resist aging for 100% at 650℃. h or more.

[0041] This invention innovatively selects γ-Al₂O₃ as a support and performs thermal modification and rapid quenching combined modification treatment on it in an oxygen-containing atmosphere. Further, a reduction precipitation system combining nanobubbles and water-soluble borohydrides is employed, unexpectedly achieving synergy. This induces abundant oxygen vacancies, and also induces PtM alloying and creates internal dislocation structures, improving the interface between the active particles and the support. Research in this invention shows that the preparation method can produce a special PtM alloy / γ-Al₂O₃ catalytic material that incorporates both oxygen vacancy and dislocation structures. Furthermore, the physicochemical structure of the material prepared by this method unexpectedly exhibits excellent low-temperature activity and high-temperature stability. Attached Figure Description

[0042] Figure 1 Pt prepared in Example 1 x Pd y Figure showing the CO catalytic oxidation performance of the / γ-Al2O3 catalyst.

[0043] Figure 2 Pt prepared in Example 1 x Pd y Figure showing the NO catalytic oxidation performance of the / γ-Al2O3 catalyst.

[0044] Figure 3 Pt prepared in Example 1 x Pd y The catalytic oxidation performance of propylene (C3H6) by the γ-Al2O3 catalyst.

[0045] Figure 4 Pt prepared in Example 1 x Pd y Graph showing the catalytic oxidation performance of propane (C3H8) by the γ-Al2O3 catalyst.

[0046] Figure 5 Pt prepared in Example 1 x Pd y / γ-Al2O3 catalytic material O 1s XPS diagram.

[0047] Figure 6 Pt prepared in Example 1x Pd y EPR spectrum of / γ-Al2O3 catalytic material.

[0048] Figure 7 Pt prepared in Example 1 x Pd y TEM image of the γ-Al2O3 catalytic material. Detailed Implementation

[0049] The following specific embodiments are intended to further illustrate the content of the present invention, rather than to further limit the scope of protection of the claims of the present invention.

[0050] Unless otherwise specified, the reagents used in the following examples are commercially available reagents purchased directly from the market.

[0051] An optional Pt of the present invention x Pd y A method for preparing γ-Al2O3 catalytic materials, comprising the following steps:

[0052] S1: Take an appropriate amount of γ-Al2O3 powder and perform pretreatment in air atmosphere; after heat preservation, perform rapid cooling while hot to obtain modified γ-Al2O3;

[0053] S2: Dissolve the dispersant in deionized water and stir until homogeneous to form solution A. Add platinum source and palladium source dropwise into solution A. Sonicate and stir the mixture until homogeneous to form solution B.

[0054] S3: Slowly add the treated γ-Al2O3 powder to the above solution B and stir.

[0055] S4: Turn on the nanobubble generator to continuously introduce particles of different sizes into the mixing system. Inert gas (argon) nanobubbles of 50~200nm, bubble concentration ≥10 8 The aeration rate was 10-15 mL / min; at the same time, sodium borohydride aqueous solution was slowly added dropwise to the mixed solution and stirred until the reaction was complete. The nano-microbubble aeration and sodium borohydride addition were carried out simultaneously. After the reduction was completed, the aeration continued for 30 min.

[0056] S5: Centrifuge the mixed solution after the reaction and collect the precipitate;

[0057] S6: Vacuum drying of the precipitate;

[0058] S7: Anneal the dried precipitate to obtain Pt. x Pd y / γ-Al2O3 catalytic materials.

[0059] As a preferred embodiment, the Pt x Pd y In the preparation of γ-Al2O3 catalyst, the mass ratio of Pt to Pd is 1~4:1; the total mass fraction of Pt and Pd can be 0.5~2%.

[0060] As a preferred technical solution, the dispersant is a polymeric dispersant; the hydrated chloroplatinic acid; the palladium source is either hydrated palladium chloride or palladium acetylacetonate; and the solvent is an aqueous solution.

[0061] As a preferred technical solution, the temperature for pretreatment of γ-Al2O3 powder is 300~500℃, and the time is 2~4 hours. h.

[0062] As a preferred technical solution, the nano-microbubbles introduced during the reduction process have a particle size of 50~200 μm. nm, bubble concentration ≥10 8 The ventilation rate is 10-15 mL / min.

[0063] As a preferred technical solution, the annealing process is as follows: under an Ar atmosphere, 3 ℃ / min ~5 Heating rate increased to 250 °C / min ℃~550 ℃, annealing time is 3~5 h.

[0064] The present invention also provides a Pt x Pd y The application of γ-Al2O3 catalysts as oxidizing catalysts for diesel vehicle exhaust treatment.

[0065] Example 1

[0066] Step 1, Pretreatment of the vector:

[0067] Take 1g γ-Al₂O₃ powder was loaded into a thermally conductive reaction vessel and, under an air atmosphere, was reacted at 5... Heating rate increased to 400 °C / min ℃, keep warm for 3 h; After the heat preservation is completed, the container is rapidly cooled to room temperature using an ice-water bath.

[0068] Step 2, Preparation of the mixed solution:

[0069] Preparation of mixed solution: Weigh 52 Dissolve mg of polyvinylpyrrolidone in 75 ml of deionized water and stir for 10 minutes. After min, solution A was obtained; 21.3 mg / L was added. mg H₂PtCl₆·6H₂O and PdCl₂·6H₂O (Pt / Pd elemental weight ratio of 2.18:1), ultrasonically treated for 10 minutes. min, stir for 0.5 min. h, to obtain solution B; take 1 from step 1. The treated γ-Al₂O₃ powder (PtPd weight percentage relative to the support is 1.18%) was slowly added to solution B above and stirred for 3 minutes. h;

[0070] Step 3, Restoration Process:

[0071] Turn on the ultrasonic nanobubble generator and continuously introduce argon nanobubbles (particle size) into the mixing system. 50~200 nm, bubble concentration 1.2×10 8 (Number of cells / mL, ultrasonic frequency approximately 50kHz), ventilation rate 12 mL / min; simultaneously weigh 25 mL / min mg sodium borohydride dissolved in 2 A sodium borohydride aqueous solution is formed in ml of deionized water, with 1 mL / min Slowly add the solution dropwise to the above solution, stirring for 1 minute. Continue ventilation for 30 h until the reaction is complete; after reduction, continue ventilation for 30 h. min.

[0072] Step 4: Centrifugal drying process:

[0073] After washing the reacted material with water and centrifuging it three times, let it stand for 60 minutes. ℃ vacuum oven drying 8 h.

[0074] Step 5, Annealing:

[0075] The material obtained in step 4 is ground and placed in a tube furnace under an Ar atmosphere at 5°C. Heating rate increased to 400 °C / min ℃, heat preservation 4 After h, the annealing was completed by natural cooling to room temperature, resulting in Pt and Pd alloy-supported alumina (Pt). x Pd y / γ-Al2O3) catalyst (also known as catalyst).

[0076] Thermocatalytic performance testing

[0077] Pt obtained x Pd y γ-Al₂O₃ powder, after being compressed into tablets, is sieved to select a particle size of [missing value]. 40~60 The target is approximately 0.5. The catalyst was used as the experimental medium, and its volume after pressing was 0.38 g. ml. The catalytic oxidation activity of the catalyst was evaluated on a multifunctional micro-quartz tube fixed-bed continuous reaction apparatus. Pre-calibrated mass flow meters were used to control the gas flow rate in each gas path, and thermocouples were inserted into the fixed reaction bed to monitor the real-time reaction temperature. The simulated diesel vehicle exhaust composition was: NO 500 ppm, CO 500 ppm, C3H6200 ppm, C3H8100 ppm, O28%, H2O 10% N2 as carrier gas, air velocity is 300000 h -1 Simulated gas is introduced, and the reaction is carried out under continuous heating conditions. The residual amount of each pollutant in the exhaust gas is detected at the outlet of the reaction tube. After the prepared reaction atmosphere is introduced until gas equilibrium is reached, it is then... 100 ℃ continuously increased to 500 Activation treatment was performed at ℃, followed by cooling to ℃. 100 ℃, wait for the temperature to stabilize before starting from 100 ℃ continuously increased to 500 The test was conducted at ℃.

[0078] Catalyst aging treatment involved placing the sample in a muffle furnace and heating it from room temperature to 650°C at a rate of 3°C / min, holding it at that temperature for 100 minutes. h.

[0079] Example 2

[0080] Compared with Example 1, the only difference is that in step 2, Pt and The mass ratio of Pd to Pt is 2:1. The total weight of Pd and other operations and parameters are the same as in Example 1.

[0081] Example 3

[0082] Compared with Example 1, the only difference is that in step 2, Pt and The mass ratio of Pd to Pt is 1:1. The total weight of Pd and other operations and parameters are the same as in Example 1.

[0083] Example 4

[0084] Compared with Example 1, the only difference is that in step 2, Pt and The mass ratio of Pd is 4:3, and the weight percentage of PtPd relative to the carrier is 1.4%. Other operations and parameters are the same as in Example 1.

[0085] Example 5

[0086] Compared with Example 1, the only difference is that in step 2, Pt and The mass ratio of Pd is 3:1, the weight percentage of PtPd relative to the carrier is 1.6%, and other operations and parameters are the same as in Example 1.

[0087] Example 6

[0088] The only difference from Example 1 is that the temperature in step 1 is 300°C. The temperature was ℃, the processing time was 4 hours, and other operations and parameters were the same as in Example 1.

[0089] Example 7

[0090] The only difference from Example 1 is that the temperature in step 1 is 500°C. The temperature was ℃, the processing time was 2 hours, and other operations and parameters were the same as in Example 1.

[0091] Example 8

[0092] Compared with Example 1, the only difference is that the annealing temperature in step 5 is 300°C and the time is 6 hours, while the other operations and parameters are the same as in Example 1.

[0093] Example 9

[0094] Compared with Example 1, the only difference is that the annealing temperature in step 5 is 500°C and the time is 3 hours. All other operations and parameters are the same as in Example 1.

[0095] Example 10

[0096] Compared with Example 1, the only difference is that the palladium source in step one is replaced with a copper source (copper nitrate; the weight of copper is the same as that of palladium).

[0097] Example 11

[0098] Compared with Example 1, the only difference is that the palladium source in step one is replaced with a cobalt source (cobalt nitrate; the weight of cobalt is the same as that of palladium).

[0099] Example 12

[0100] Compared with Example 1, the only difference is that the palladium source in step one is replaced with a manganese source (manganese nitrate; the weight of manganese is the same as that of palladium).

[0101] Comparative Example 1

[0102] Compared with Example 1, the only difference is that in step 1, no palladium source was added, and the amount of remaining Pt was the same as the total weight of PtPd elements in Example 1. All other operations and parameters were the same as in Example 1.

[0103] Comparative Example 2

[0104] Compared with Example 1, the only difference is that in step 1, no platinum source was added, the amount of remaining Pd is the same as the total weight of PtPd elements in Example 1, and all other operations and parameters are the same as in Example 1.

[0105] Comparative Example 3

[0106] Compared with Example 1, the only difference is that γ-Al2O3 was not processed in step 1, but directly underwent step 2 and subsequent processing. All other operations and parameters were the same as in Example 1.

[0107] Comparative Example 4

[0108] Compared with Example 1, the only difference is that no rapid cooling treatment was performed. Instead, the heat preservation treatment was followed by furnace cooling. All other operations and parameters are the same as in Example 1.

[0109] Comparative Example 5

[0110] Compared with Example 1, the only difference is that in step 3, sodium borohydride was not added, and the above solution was evaporated and desolventized or reduced and annealed under a hydrogen atmosphere. All other operations and parameters are the same as in Example 1.

[0111] Comparative Example 6

[0112] Compared with Example 1, the only difference is that the γ-Al2O3 powder support is replaced with CeO2 support, and all other operations and parameters are the same as in Example 1.

[0113] Comparative Example 7

[0114] Compared with Example 1, the only difference is that the γ-Al2O3 powder support is replaced with the α-Al2O3 support, and all other operations and parameters are the same as in Example 1.

[0115] Comparative Example 8

[0116] Compared with Example 1, the only difference is that in step 3, nanobubbles are not introduced during the reduction process.

[0117] Comparative Example 9

[0118] Compared with Example 1, the only difference is that in step 3, the reducing agent sodium borohydride is replaced with hydrazine hydrate solution, and all other operations and parameters are the same as in Example 1.

[0119] Comparative Example 10

[0120] Compared with Example 1, the only difference is that in step 3, the reducing agent sodium borohydride is replaced with formaldehyde solution, and the pH of the solution is adjusted to 10.5 with NaOH. All other operations and parameters are the same as in Example 1.

[0121] Comparative Example 11

[0122] Compared with Example 1, the only difference is that in step 3, the reducing agent sodium borohydride is replaced with oxalic acid solution, and the temperature is maintained at 60°C for 4 hours. All other operations and parameters are the same as in Example 1.

[0123] The results for each case are shown in Table 1:

[0124]

[0125] Note: Fresh sample refers to a newly prepared sample. Aged sample refers to a sample that has been aged under the conditions described.

[0126] For example, in Table 1, the data in (a) refer to: the maximum NO2 / NO2 ratio of fresh samples. x Percentage (%); and the maximum NO2 / NO2 ratio of the aged samples. x Percentage (%)

[0127] (b) refers to the CO ignition temperature T50 (°C) of the fresh sample and the CO ignition temperature T50 (°C) of the aged sample.

[0128] (c) refers to the C3H6 ignition temperature T50 (°C) of fresh samples and the C3H6 ignition temperature T50 (°C) of aged samples.

[0129] (d) refers to the C3H8 ignition temperature T50 (°C) of the fresh sample and the C3H8 ignition temperature T50 (°C) of the aged sample.

[0130] T50 refers to the temperature at which the pollutant conversion rate reaches 50%.

[0131] Examples 1, 2, 3, 4, and 5 investigated catalysts prepared with different Pt-Pd mass ratios and their performance tests. Example 1 used Pt... x Pd yThe γ-Al₂O₃ catalyst exhibited the best catalytic activity and stability. The tests of fresh and aged catalysts at the scale of Example 1 are illustrated. NO2 / NO x The proportion reached 53 The percentage and 48% were significantly higher than those in Examples 2, 3, 4, and 5, indicating that the catalyst at this ratio had a better effect on the desired effect. NO The CO in Example 1 exhibits the best oxidation conversion ability and anti-aging stability. T 50 (108 / 142) ℃), C3H6T 50 (127 / 156) ℃) for all PtPd The lowest ratio in the group, and the smallest performance degradation after aging, indicates that the performance formed at this ratio is... PtPd The alloy structure is more conducive to improving low-temperature oxidation activity and anti-aging properties; each PtPd The proportion of fresh states can all be achieved C3H8100 % Conversion, Example 1: Aging state conversion rate (98%) (%) remains the highest among all groups, reflecting its advantage in catalytic stability for low-carbon alkanes.

[0132] Examples 1, 6, and 7 investigated catalysts prepared at different γ-Al₂O₃ pretreatment temperatures and their performance tests. The support pretreatment temperature was 400 °C. ℃ At this time, the catalyst exhibits optimal overall performance.

[0133] Examples 1, 8, and 9 investigated catalysts prepared at different annealing temperatures and their performance tests. The 400 annealing temperature in Example 1... Annealing at ℃ is the optimal condition, at which the catalyst exhibits the best catalytic activity and the performance degradation after aging is minimal.

[0134] Examples 1, 10, 11, and 12 investigated catalysts prepared by forming alloys with Pt using different metal elements and their performance tests. Bimetallic alloys exhibit significantly better activity and stability than... Cu / Co / Mn Non-precious metal alternatives are used in diesel vehicles. DOC The optimal combination of active components for a catalyst.

[0135] By comparing Comparative Example 1 with Example 1, the catalyst obtained in Comparative Example 1 without the addition of a palladium source showed a significant difference in performance and stability compared to Example 1.

[0136] By comparing Comparative Example 2 with Example 1, the catalyst obtained in Comparative Example 2 without the addition of a platinum source is insufficient in terms of both performance and stability.

[0137] As can be seen from the comparison between Example 1 and Comparative Examples 3 and 4, the oxygen vacancies constructed by the present invention through a specific preparation process synergistically with the PtPd alloy. The carrier pretreatment-rapid cooling modification causes lattice distortion in the γ-Al2O3 powder, preventing the lattice from returning to regularity, while retaining more hydroxyl groups. During the subsequent sodium borohydride reduction process, the hydride anions (H+) provided by the anions (H+) - The oxygen vacancies react with the hydroxyl groups retained on the support surface, forming stable oxygen vacancies on the support surface. This treatment significantly improves the low-temperature activity and thermal stability of the catalyst, demonstrating a clear technological advantage. The improved thermal stability is due to the fact that oxygen vacancies promote electron transfer between the support and the PtPd alloy, inhibiting the agglomeration and sintering of noble metal particles.

[0138] As can be seen from Example 1 and Comparative Example 5, sodium borohydride is the only effective reducing agent for the directional generation of oxygen vacancies. Although high-temperature reduction with hydrogen can reduce... PtPd Ions, but unable to interact with The hydroxyl groups on the surface of γ-Al2O3 produce a synergistic effect.

[0139] As can be seen from Example 1 and Comparative Examples 6 and 7, γ-Al2O3 is suitable for the generation of oxygen vacancies and PtPd The only support for catalysis, CeO2, has poor crystal stability and excessively strong interaction with PtPd, which inhibits catalytic activity; α-Al2O3 has a small specific surface area and very few surface hydroxyl groups, so it cannot provide active sites for oxygen vacancy generation, nor can it disperse the catalytic activity. PtPd Particles; only Only γ-Al2O3 can support the dual requirements of oxygen vacancy generation and active component dispersion.

[0140] The comparison between Example 1 and Comparative Example 8 shows that the introduction of nanobubbles is crucial for improving catalytic performance. Without the introduction of nanobubbles, both catalytic activity and stability decrease, demonstrating the unique role of nanobubbles in mass transfer enhancement and alloy dispersion optimization.

[0141] As can be seen from the comparison between Example 1 and Comparative Examples 9, 10 and 11, only when sodium borohydride is used as a reducing agent can the construction of oxygen vacancies and dislocation structures be achieved simultaneously, thereby enabling the PtPd alloy to exhibit catalytic performance far exceeding that of pure Pd.

[0142] The above results compare and illustrate factors such as support selection, element type, support pretreatment temperature, material annealing temperature, and alloy composition ratio. The performance of the final catalyst is closely related to the above factors, and it is necessary to comprehensively adjust each parameter to obtain the optimal catalyst.

[0143] The above results demonstrate that the Pt obtained in this invention... x Pd y / γ-Al2O3 catalysts have excellent catalytic activity and stability, low precious metal content, and simple preparation methods, making them suitable for large-scale application in diesel vehicle exhaust purification.

[0144] Specific embodiments of the present invention have been described. However, the present invention is not limited to the above embodiments. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A PtM alloy / γ-Al2O3 catalytic material with an oxygen vacancy-dislocation structure, comprising a support and its supported active components, characterized in that: The carrier is oxygen-deficient γ-Al2O3, and the active ingredient is PtM nano-alloy particles with dislocation structure. In PtM, M includes at least one of Pd, Cu, Co, and Mn; the mass ratio of Pt to M is 1 to 4:

1. In the oxygen vacancy-dislocation structure PtM alloy / γ-Al2O3 catalytic material, the content of the active component is 0.1~5 wt.%. The preparation method of the oxygen vacancy-dislocation structure PtM alloy / γ-Al2O3 catalytic material is as follows: γ-Al2O3 is pre-heat modified by heat treatment at 300~500℃ in an oxygen-containing atmosphere, followed by rapid cooling to obtain modified γ-Al2O3. Modified γ-Al2O3, platinum source, M source, and reducing agent were mixed in liquid phase and reduced and precipitated with the assistance of nano-microbubbles to obtain a precipitate with PtM alloy deposited on modified γ-Al2O3; the reducing agent was a water-soluble borohydride. The precipitate was then annealed to obtain the oxygen vacancy-dislocation structure PtM alloy / γ-Al2O3 catalytic material.

2. The oxygen vacancy-dislocation structure PtM alloy / γ-Al2O3 catalytic material as described in claim 1, characterized in that, The Pt:M mass ratio in the active ingredient is 1~2.5:1, and its particle size is 5~10nm; In the oxygen vacancy-dislocation structure PtM alloy / γ-Al2O3 catalytic material, the content of active components is 0.5~2Wt.%.

3. A method for preparing the oxygen vacancy-dislocation structure PtM alloy / γ-Al2O3 catalytic material according to any one of claims 1 to 2, characterized in that, γ-Al2O3 was preheated in an oxygen-containing atmosphere at 300~500℃ and then rapidly cooled to obtain modified γ-Al2O3. Modified γ-Al2O3, platinum source, M source, and reducing agent were mixed in liquid phase and reduced and precipitated with the assistance of nano-microbubbles to obtain a precipitate with PtM alloy deposited on modified γ-Al2O3; the reducing agent was a water-soluble borohydride. The precipitate was then annealed to obtain the oxygen vacancy-dislocation structure PtM alloy / γ-Al2O3 catalytic material.

4. The preparation method of the oxygen vacancy-dislocation structure PtM alloy / γ-Al2O3 catalytic material as described in claim 3, characterized in that, The oxygen-containing atmosphere is an atmosphere containing oxygen, wherein the oxygen content is above 5%; the thermal modification time is 1~5 hours. The cooling medium for rapid cooling is a flowing liquid or solid with a temperature below 10°C.

5. The preparation method of the oxygen vacancy-dislocation structure PtM alloy / γ-Al2O3 catalytic material as described in claim 3, characterized in that, The platinum source is hydrated chloroplatinic acid; The M source is a water-soluble compound of element M; In the initial solution system for reducing precipitation, the concentration of the platinum source is 0.4~0.55 mmol / L; The initial solution system for reducing precipitation also contains a polymeric dispersant at a concentration of 0.6–0.7 mg / mL. In the initial solution system for reducing precipitation, the total weight of PtM elements is 0.1~5Wt. of the weight of modified γ-Al2O3.

6. The preparation method of the oxygen vacancy-dislocation structure PtM alloy / γ-Al2O3 catalytic material as described in claim 3, characterized in that, Inert gas nanobubbles with a particle size of 50-200 nm are continuously introduced into the mixed solution system of the reduction precipitation process, with a bubble concentration ≥10. 8 The number of cells / mL and the ventilation rate are 10~15mL / min; The reduction and precipitation time assisted by nano-microbubbles is 20~60 min.

7. The preparation method of the oxygen vacancy-dislocation structure PtM alloy / γ-Al2O3 catalytic material as described in claim 3, characterized in that, The atmosphere during the annealing stage is at least one of nitrogen and rare gases; The annealing process is carried out at temperatures ranging from 250℃ to 550℃. Annealing time is 1 to 8 hours.

8. The application of the oxygen vacancy-dislocation structure PtM alloy / γ-Al2O3 catalytic material according to any one of claims 1 to 2, or the oxygen vacancy-dislocation structure PtM alloy / γ-Al2O3 catalytic material prepared by any one of claims 3 to 7, characterized in that, It is used as a catalyst for the catalytic treatment of automobile exhaust.

9. The application as described in claim 8, characterized in that, The vehicle exhaust gas mentioned is diesel combustion exhaust gas.

10. A tail gas treatment device, comprising a tail gas catalyst, characterized in that, The exhaust gas catalyst comprises the oxygen vacancy-dislocation structure PtM alloy / γ-Al2O3 catalyst material as described in any one of claims 1 to 2, or the oxygen vacancy-dislocation structure PtM alloy / γ-Al2O3 catalyst material prepared by any one of claims 3 to 7.

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