Modified aluminum oxide catalyst as well as preparation method and application thereof
By introducing silicon modification and loading Pt and/or Ni/Cu into the alumina catalyst, the problems of insufficient activity of alumina catalyst and high cost of precious metals are solved, and efficient and low-cost diesel engine exhaust purification is achieved.
Patent Information
- Application Number
- CN202510464065.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-14
- Publication Date
- 2025-07-04
AI Technical Summary
The existing alumina catalysts have limited activity in diesel engine exhaust purification, and traditional precious metal catalysts have high cost and poor stability, making it difficult to meet the needs of efficient purification.
Silicon modified alumina is used as the support and Pt and/or Ni/Cu are supported as the first and second components to improve catalytic activity through synergistic action and reduce the amount of precious metals.
The activity of the catalyst is improved, the amount of precious metals is reduced, and the stability and cost-effectiveness of the catalyst are enhanced.
Smart Images
Figure CN120243057A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of catalysts, and particularly relates to a modified alumina catalyst, a preparation method thereof, and an application thereof. Background Art
[0002] As one of the effective means for tail gas purification, the performance of the catalyst plays a key role.
[0003] Alumina is an important inorganic material with many excellent physical and chemical properties. It has a high specific surface area, which provides sufficient active sites for catalytic reactions; good thermal stability enables it to maintain a stable structure in high-temperature environments, facilitating the catalytic process; chemical inertness ensures that it will not undergo unnecessary chemical reactions with reactants or products in a complex chemical reaction environment, thus ensuring the selectivity and stability of the catalytic reaction. Based on these advantages, alumina is widely used as a catalyst support or the catalyst itself.
[0004] Although alumina has many advantages, unmodified alumina has limited activity in certain specific catalytic reactions. Relying solely on the properties of alumina itself, it is difficult to meet the strict requirements for efficient purification of diesel engine tail gas. Therefore, it is necessary to modify alumina to improve its catalytic activity.
[0005] In the field of diesel engine tail gas treatment, noble metals such as platinum (Pt) and palladium (Pd) are traditionally commonly used as catalysts. These noble metal catalysts exhibit good catalytic activity and can effectively promote chemical reactions of harmful components in the tail gas, converting them into harmless substances. However, the prices of noble metals such as platinum and palladium are high, and the global resource reserves are limited. This has significantly increased the cost of using noble metal catalysts and restricted their wide application in the field of large-scale tail gas purification. In addition to cost and resource issues, noble metal catalysts have poor stability under high temperature and harsh environments. High temperature and complex tail gas components will cause changes in the structure of noble metal catalysts, leading to the failure of active sites, thereby reducing the catalytic efficiency and service life. This further increases the cost of tail gas treatment and the maintenance difficulty.
[0006] In the field of diesel engine tail gas purification, existing catalysts have various problems. Unmodified alumina has limited catalytic activity, traditional noble metal catalysts have high costs and poor stability, and existing preparation technologies for modified alumina catalysts still face many challenges. To meet the demand for low-cost and high-performance catalysts in tail gas purification, the development of new modified alumina catalysts and their preparation methods has important practical significance. Summary of the Invention
[0007] Aiming at the deficiencies of the above-mentioned existing technologies, the purpose of the present invention is to provide a modified alumina catalyst, its preparation method and application, which can effectively improve the activity of the catalyst while reducing the noble metal content in the catalyst.
[0008] In the first aspect, the present invention provides a modified alumina catalyst, wherein the catalyst uses silicon-modified alumina as a carrier, and the metals supported on the carrier include a first component and a second component. The first component includes Pt, and the second component includes Ni and / or Cu.
[0009] Further, the weight ratio of the carrier to the supported metals is 1000:1 - 5.
[0010] Further, the preparation method of the silicon-modified alumina includes: mixing γ-Al2O3, polydimethylsiloxane and acetone and stirring to obtain a paste, standing to obtain a white powder, drying the white powder at 200 °C for 1 h, then calcining at 400 °C for 1 h, then calcining at 600 °C for 1 h, and finally calcining at 800 °C for 1 h to obtain it.
[0011] Further, the dosage ratio of γ-Al2O3, polydimethylsiloxane and acetone is 5 g: 2.05 g: 10 mL.
[0012] Further, the second component is Cu.
[0013] Further, the molar ratio of the first component to the second component is 10:1 - 10.
[0014] Further, the molar ratio of the first component to the second component is 10:1 - 5.
[0015] Further, the molar ratio of the first component to the second component is 10:3 - 1.
[0016] Further, the second component includes two kinds. The first kind is Cu, and the second kind is Ni.
[0017] In the second aspect, the preparation method of the modified alumina catalyst in the present invention includes the steps of: mixing and dispersing the silicon-modified alumina with water, dropping a supported metal solution into it and stirring to obtain a mixed solution, concentrating the mixed solution under reduced pressure, and then calcining at 400 - 500 °C to obtain the modified alumina catalyst.
[0018] Further, the content ratio of water to metal in the supported metal solution is 100 mL: (52.3 - 66.6) mg.
[0019] Further, the preparation method of the supported metal solution includes: adding tetraammineplatinum nitrate, copper sulfate pentahydrate and nickel nitrate hexahydrate to water and stirring evenly to obtain it.
[0020] Further, the weight ratio of tetraammineplatinum nitrate, copper sulfate pentahydrate and nickel nitrate hexahydrate is (0.05 - 0.15):(0 - 0.0325):(0 - 0.0378).
[0021] In a third aspect, the modified alumina-based catalyst of the present invention is applied to the catalytic oxidation of diesel exhaust gas.
[0022] The beneficial effects of the present invention are as follows: The modified alumina-based catalyst of the present invention uses silicon-modified alumina as a carrier, and the loaded metal is at least two components. The first component is Pt, and the second component includes Ni and / or Cu. The amount of precious metal used is reduced, and the first component and the second component act synergistically to improve the activity of the catalyst. Description of the Drawings
[0023] Figure 1 It is a scanning electron micrograph of the modified alumina-based catalyst B1 obtained in Preparation Example 1 of the present invention. Detailed Embodiments
[0024] The technical solutions of the present invention will be described clearly and completely below. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.
[0025] The present invention provides a modified alumina catalyst. The catalyst uses silicon-modified alumina as a carrier, and the metal loaded on the carrier includes a first component and a second component. The first component is Pt, and the second component includes Ni and / or Cu; the weight ratio of the carrier to the loaded metal is 1000:1 - 5; the molar ratio of the first component to the second component is 10:1 - 10.
[0026] Among them, the preparation method of the silicon-modified alumina includes: taking 5.0 g of γ-Al2O3 and placing it in a 100 mL crucible, adding a solution prepared from 2.05 g of polydimethylsiloxane with a viscosity of 620 centipoises and 10 mL of acetone, stirring at 25°C for 15 min, allowing the obtained paste to stand at room temperature for 4 hours to obtain a white powder. The above white powder is dried at 200°C for 1 h, then calcined at 400°C for 1 h, then calcined at 600°C for 1 h, and finally calcined at 800°C for 1 h to obtain.
[0027] The polydimethylsiloxane has the following structure:
[0028] Among them, R1, R2, and R3 in the polydimethylsiloxane are all methyl groups, m is 8, and n is zero.
[0029] The present invention provides a method for preparing a modified alumina catalyst. The steps include: mixing and dispersing silicon-modified alumina with water, dropping a metal-loaded solution into it and stirring to obtain a mixed solution, concentrating the mixed solution under reduced pressure, and then calcining at 400 - 500 °C to obtain the modified alumina catalyst; the content ratio of water to metal in the metal-loaded solution is 100 mL : (52.3 - 66.6) mg.
[0030] Among them, the preparation steps of the metal-loaded solution include: adding 100 mL of pure water into a three-necked flask, and then adding tetraammineplatinum(II) nitrate, copper sulfate pentahydrate, nickel nitrate hexahydrate, and stirring evenly to prepare a solution of the metal-loaded solution; the weight ratio of tetraammineplatinum nitrate, copper sulfate pentahydrate, and nickel nitrate hexahydrate is (0.05 - 0.15) : (0 - 0.0325) : (0 - 0.0378).
[0031] The batches of the metal-loaded solution prepared by the foregoing preparation method are shown in detail in the following table:
[0032] Preparation Example 1 Preparation of Modified Alumina-Based Catalyst B1 Add 20 g of silicon-modified alumina powder into three-necked flask A, then add 100 mL of water, ultrasonically disperse for 60 min, and then add metal-loaded solution B1. The total amount of metal in the metal-loaded solution is 20 mg (the amount of metal-loaded solution B1 is 30 mL). Stir for 2 hours, and then concentrate under reduced pressure for 6 hours until no liquid comes out. Then calcine the obtained solid at 500 °C for 2 hours to obtain modified alumina-based catalyst B1.
[0033] Preparation Example 2 Preparation of Modified Alumina-Based Catalyst B2 Referring to the preparation of modified alumina-based catalyst B1 in Preparation Example 1, replace metal-loaded solution B1 with metal-loaded solution B2. In the metal-loaded solution B2 used, the total amount of metal is 20 mg. Modified alumina-based catalyst B2 is prepared.
[0034] Preparation Example 3 Preparation of Modified Alumina-Based Catalyst B3 Referring to the preparation of modified alumina-based catalyst B1 in Preparation Example 1, replace metal-loaded solution B1 with metal-loaded solution B3. In the metal-loaded solution B3 used, the total amount of metal is 20 mg. Modified alumina-based catalyst B3 is prepared.
[0035] Preparation Example 4 Preparation of Modified Alumina-Based Catalyst B4 Referring to the preparation of modified alumina-based catalyst B1 in Preparation Example 1, replace metal-loaded solution B1 with metal-loaded solution B4. In the metal-loaded solution B4 used, the total amount of metal is 20 mg. Modified alumina-based catalyst B4 is prepared.
[0036] Preparation Example 5 Preparation of Modified Alumina-based Catalyst C2 Referring to the preparation of the modified alumina-based catalyst B1 in Preparation Example 1, the metal loading solution B1 was replaced with the metal loading solution C2. In the used metal loading solution C2, the total amount of metal was 20 mg. The modified alumina-based catalyst C2 was prepared.
[0037] Preparation Example 6 Preparation of Modified Alumina-based Catalyst D2 Referring to the preparation of the modified alumina-based catalyst B1 in Preparation Example 1, the metal loading solution B1 was replaced with the metal loading solution D2. In the used metal loading solution D2, the total amount of metal was 20 mg. The modified alumina-based catalyst D2 was prepared.
[0038] A mixed gas containing CO, propylene, NO, H2O, O2, and N2 was introduced into a tubular furnace, where CO: 600 ppm, propylene: 500 ppm, NO: 600 ppm, H2O: 5%, O2: 10%, with N2 as the balance gas, and the space velocity was 20000 / h. First, each gas was adjusted and introduced into a gas mixing tank, stabilized to the set value, and used as the initial emission data for calculating the conversion rate. Then, the uniformly mixed gas was introduced into the tubular furnace containing the catalyst, and the temperature was raised from 50 °C to 500 °C at a heating rate of 5 °C / min. At a rate of 2 s / each time, the values of each gas after passing through the catalyst were recorded, and the conversion rate was calculated. The test results are shown in the following table.
[0039] The Fourier transform infrared spectrometer used in this test is: MKS Multigas2030HS.
[0040]
[0041] As can be seen from Application Examples 1-4, with the increase in the proportion of the first component, the performance of catalyzing CO first increases and then decreases. In Application Example 3, the modified alumina-based catalyst B3 was used, and the molar ratio of the first component Pt to the second component (Cu and Ni) was 10:3, and its performance was relatively excellent.
[0042] As can be seen from Application Examples 1-4, with the increase in the proportion of the first component, the performance of catalyzing propylene increases. In Application Example 4, the modified alumina-based catalyst B4 was used, and the molar ratio of the first component Pt to the second component (Cu and Ni) was 10:1, and its performance was relatively excellent.
[0043] As can be seen from Application Examples 1-4, with the increase of the proportion of the first component, the performance of catalyzing NO decreases. For the modified alumina-based catalyst B1 used in Application Example 1, the molar ratio of the first component Pt to the second component (Cu and Ni) is 10:10. For the modified alumina-based catalyst B2 used in Application Example 2, the molar ratio of the first component Pt to the second component (Cu and Ni) is 10:4. Their performances are both excellent. Considering cost factors, the modified alumina-based catalyst B2 used in Application Example 2 is more preferable.
[0044] For the modified alumina-based catalyst C2 used in Application Example 5, the supported metals are Pt and Cu. For the modified alumina-based catalyst D2 used in Application Example 6, the supported metals are Pt and Ni. Among them, the performance of catalyzing CO in Application Example 5 is good. The performance of catalyzing NO in Application Example 6 is good.
[0045] Finally, it should be noted that the above embodiments are only used to illustrate the present invention rather than to limit the technical solutions described in the present invention; those of ordinary skill in the art should understand that the present invention can still be modified or equivalently replaced; and all technical solutions and their improvements that do not depart from the spirit and scope of the present invention should be covered by the scope of the claims of the present invention.
Claims
1. A modified alumina catalyst, characterized in that, The catalyst uses silicon-modified alumina as the carrier, and the metals supported on the carrier include a first component and a second component. The first component includes Pt, and the second component includes Ni and / or Cu.
2. The modified alumina catalyst according to claim 1, wherein, The weight ratio of the carrier to the supported metals is 1000:1 - 5.
3. The modified alumina catalyst according to claim 1, wherein The preparation method of the silicon-modified alumina includes: mixing γ-Al2O3, polydimethylsiloxane, and acetone and stirring to obtain a paste, standing to obtain a white powder, drying the white powder at 200 °C for 1 h, then calcining at 400 °C for 1 h, then calcining at 600 °C for 1 h, and finally calcining at 800 °C for 1 h to obtain.
4. A modified alumina catalyst according to claim 3, wherein, The dosage ratio of the γ-Al2O3, polydimethylsiloxane, and acetone is 5 g : 2.05 g : 10 mL.
5. A modified alumina catalyst according to claim 1, characterized in that, The molar ratio of the first component to the second component is 10 : 1 - 10.
6. A method for preparing a modified alumina catalyst according to any one of claims 1-5, characterized in that the steps Including: Mixing and dispersing the silicon-modified alumina with water, dropping the supported metal solution into it and stirring to obtain a mixed solution, concentrating the mixed solution under reduced pressure, and then calcining at 400 - 500 °C to obtain the modified alumina catalyst.
7. The preparation method of the modified alumina catalyst according to claim 6, wherein The content ratio of water to metal in the supported metal solution is 100 mL : (52.3 - 66.6) mg.
8. The preparation method of the modified alumina catalyst according to claim 6, characterized in that, The preparation method of the supported metal solution includes: adding tetraammineplatinum nitrate, copper sulfate pentahydrate, and nickel nitrate hexahydrate to water and stirring evenly.
9. The preparation method of the modified alumina catalyst according to claim 7, wherein, The weight ratio of the tetraammineplatinum nitrate, copper sulfate pentahydrate, and nickel nitrate hexahydrate is (0.05 - 0.15) : (0 - 0.0325) : (0 - 0.0378).
10. Application of a modified alumina catalyst as described in any one of claims 1 - 5 in the catalytic oxidation of diesel exhaust gas.