Method for controllably preparing mesoporous Mn-based composite metal oxide in one step
The one-step preparation of mesoporous Mn-based composite metal oxide catalysts solves the problems of complex preparation methods and high costs in existing technologies, and achieves efficient catalytic oxidation of volatile organic compounds, showing good prospects for industrial application.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-01-22
- Publication Date
- 2026-04-14
AI Technical Summary
Existing methods for preparing mesoporous composite metal oxide catalysts are cumbersome, time-consuming, and energy-intensive, and the controllability of the target product is weak, making them difficult to promote and industrialize.
A mesoporous Mn-based composite metal oxide catalyst was prepared by mixing a manganese source, a second metal source, and an organic auxiliary agent in a one-step process and then subjecting the mixture to stepwise calcination. The catalyst consisted of a 50% manganese nitrate solution as the manganese source, a metal nitrate or nano-oxide as the second metal source, and tartaric acid or citric acid as the organic auxiliary agent. The calcination temperature and heating rate were controlled, and the catalyst was obtained after washing and drying.
The prepared catalyst has a large specific surface area, excellent mesoporous structure, ideal catalytic effect, low cost, and is easy to industrialize, making it suitable for the catalytic oxidation of volatile organic compounds.
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Figure CN121847166A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of inorganic functional material preparation technology, specifically relating to a one-step controllable method for preparing mesoporous Mn-based composite metal oxides for catalytic oxidation of volatile organic compounds (VOCs). Background Technology
[0002] Volatile organic compounds (VOCs) are among the most common air pollutants. Besides anthropogenic sources, microorganisms, plants, and animals also release these substances. High concentrations of VOCs not only directly harm human health but also participate in photochemical reactions, forming secondary pollutants.
[0003] Compared with precious metals, transition metal oxide catalysts are inexpensive, highly tunable, and have good thermal stability, and are commonly used as catalysts for the catalytic removal of VOCs. The composition, valence state, and interactions between different metals and their oxides all affect their performance (Wei Gao, Xiaolong Tang, Honghong Yi, et al. Journal of Environmental Sciences, 2023, 125: 112-134.). The concentration of oxygen species on the surface, lattice oxygen defects, or oxygen vacancies on the surface of catalysts for the oxidation removal of VOCs directly affects their performance. The oxide of lanthanide element cerium, CeO2, has excellent oxygen storage capacity, and the introduction of cerium components can improve catalyst performance (Siyu Gao, Di Yu, Shengran Zhou, et al. Journal of Materials Chemistry A, 2023, 11(36): 19210-19243.). Mesoporous materials possess both intrinsic material properties and the characteristics of porous structures, and their physicochemical properties are significantly superior to those of bulk materials. Currently, the preparation methods for mesoporous composite metal oxides include soft template method, hard template method, nano-replication method, precipitation method, etc. These methods have disadvantages such as cumbersome steps, time and energy consumption, weak controllability of target products, and difficulty in promotion and industrialization. Summary of the Invention
[0004] The present invention aims to overcome the shortcomings of the prior art and provide a one-step controllable method for preparing mesoporous Mn-based composite metal oxide catalysts, which is simple in process, low in cost, has a large specific surface area, ideal catalytic effect, and strong versatility.
[0005] To solve the above-mentioned technical problems, the present invention is implemented as follows:
[0006] A method for one-step controllable preparation of mesoporous Mn-based composite metal oxide catalysts includes the following steps:
[0007] (1) Mix the manganese source, the second metal source and the organic auxiliary agent to obtain a mixed precursor;
[0008] The manganese source is a 50% manganese nitrate solution; the second metal source is a nitrate, oxalate, or nano-oxide of a second metal; the organic auxiliary is tartaric acid or citric acid;
[0009] (2) The mixed precursor obtained in step (1) is subjected to stepwise calcination: first, it is kept at 110-120℃ for 100-200 minutes, and then kept at 450-700℃ for 200-300 minutes to obtain the primary product;
[0010] (3) The primary product is washed and dried to obtain the target product, mesoporous Mn-based composite metal oxide catalyst.
[0011] Further, in step (1), the molar ratio of manganese element in the manganese nitrate solution, second metal element in the second metal source, and organic auxiliary agent is 1:0.3-3:0.3-3.
[0012] Furthermore, the second metal element in the second metal source is selected from Ni, Co, or Ce.
[0013] Furthermore, the second metal source is any one of nickel nitrate, nickel oxalate, nano nickel oxide, cobalt nitrate, cobalt oxalate, nano cobalt oxide, cerium nitrate, cerium oxalate, and nano cerium oxide.
[0014] Furthermore, in step (2), the heating rate from room temperature to 110-120°C is 1°C / min, and the heating rate from 110-120°C to 450-700°C is 1°C / min.
[0015] Furthermore, the washing process involves alternating between deionized water and anhydrous ethanol.
[0016] The mesoporous Mn-based composite metal oxide catalyst prepared by the above method has a specific surface area of 74–108 m². 2 / g; the catalyst has a mesoporous structure with an average pore size of 3.8–10.2 nm.
[0017] The present invention also provides the application of the above-mentioned catalyst in the catalytic oxidation of volatile organic compounds.
[0018] The catalyst of this invention uses tartaric acid or citric acid as an auxiliary agent, a 50% manganese nitrate solution as the manganese source, and metal nitrates or nano-oxides as the metal source. These are thoroughly mixed in a specific ratio and then calcined in steps to produce MnNiO with a mesoporous structure. a MnCoO b MnCeO cComposite oxide particles. The advantages of this catalyst lie in the low cost of the raw materials used and the simple and universally applicable preparation method. Mn-based composite metal oxide catalysts with different structural characteristics can be controllably prepared by adjusting the type and molar ratio of the metal, as well as the ratio with the auxiliary agent. The resulting catalysts have a large specific surface area and excellent catalytic oxidation performance for VOCs, showing good prospects for industrial application in electrochemistry and materials science. Specifically, this invention has the following characteristics compared with existing technologies:
[0019] (1) The present invention can form a mesoporous structure through simple physical mixing and segmented calcination, eliminating the need for complex template removal and other steps. The process is short, easy to operate, and easy to scale up for industrial production.
[0020] (2) The manganese source, the second metal source and the organic auxiliary agent selected in this invention are all common chemicals, which are inexpensive and widely available, thus significantly reducing production costs.
[0021] (3) By selecting different second metal sources and adjusting the molar ratio between each component, the present invention can controllably prepare a series of Mn-based composite metal oxides with different compositions, and the product structure is stable.
[0022] (4) The catalyst prepared by the present invention has a high specific surface area and a suitable mesopore size, providing abundant active sites and good material transport channels for the catalytic oxidation of VOCs, and exhibits excellent catalytic performance. Attached Figure Description
[0023] Figure 1 Mesoporous MnNiO obtained in Example 1 a1 XRD patterns.
[0024] Figure 2 Mesoporous MnNiO obtained in Example 2 a2 SEM images.
[0025] Figure 3 Mesoporous MnNiO obtained in Example 3 a3 The BET curve.
[0026] Figure 4 Mesoporous MnCoO obtained in Example 4 b1 XRD patterns.
[0027] Figure 5 Mesoporous MnCoO obtained in Example 5 b2 SEM images.
[0028] Figure 6 Mesoporous MnCoO obtained in Example 6 b3 The BET curve.
[0029] Figure 7 Mesoporous MnCeO obtained in Example 7 c1 XRD patterns.
[0030] Figure 8 Mesoporous MnCeO obtained in Example 8 c2 SEM images.
[0031] Figure 9 Mesoporous MnCeO obtained in Example 9 c3 The BET curve. Detailed Implementation
[0032] The present invention will now be described in detail through specific embodiments. These embodiments are provided to enable a more thorough understanding of the invention and to fully convey the scope of the invention to those skilled in the art. As used throughout the specification and claims, the terms "comprising" or "including" are open-ended and are interpreted as "comprising but not limited to". The following description is a preferred embodiment for carrying out the invention; however, this description is intended to illustrate the general principles of the specification and is not intended to limit the scope of the invention. The scope of protection of the invention is determined by the appended claims. Unless otherwise specified, all reagents and materials used in the present invention are commercially available.
[0033] Example 1
[0034] Weigh 1.745 g of nickel nitrate and grind it into a fine powder in an agate mortar. Then weigh 7.800 g of tartaric acid and grind it into a fine powder in the same mortar. Mix the two powders thoroughly, and slowly add 7.160 g of 50% manganese nitrate solution while stirring constantly. Disperse the resulting mixture evenly in a porcelain boat, place it in a muffle furnace, and heat it to 110°C at a rate of 1°C / min, holding it for 120 minutes. Then continue heating to 450°C and holding it for 200 minutes. After naturally cooling to room temperature, remove the sample and wash it three times with 5 mL of deionized water and anhydrous ethanol, respectively, to obtain mesoporous MnNiO. a1 The product has a specific surface area of 102 m². 2 / g.
[0035] Example 2
[0036] 1.494 g of nano-nickel oxide was weighed and ground thoroughly in an agate mortar. Then, 6.000 g of tartaric acid was weighed and ground into a fine powder in the same mortar. The two were mixed thoroughly, and 7.160 g of 50% manganese nitrate solution was slowly added dropwise while stirring constantly. The resulting mixture was evenly dispersed in a porcelain boat and placed in a muffle furnace. The temperature was increased to 120°C at a rate of 1°C / min and held for 150 minutes. The temperature was then increased to 450°C and held for 220 minutes. After naturally cooling to room temperature, the sample was removed and washed three times with 5 mL of deionized water and anhydrous ethanol, respectively, to obtain mesoporous MnNiO. a2 The product has a specific surface area of 85m². 2 / g.
[0037] Example 3
[0038] Weigh 7.270 g of nickel oxalate and grind it thoroughly in an agate mortar. Then weigh 14.175 g of citric acid and grind it into a fine powder in the same mortar. Mix the two powders thoroughly, and slowly add 7.160 g of 50% manganese nitrate solution while stirring constantly. Disperse the resulting mixture evenly in a porcelain boat and place it in a muffle furnace. Heat the boat to 120°C at a rate of 1°C / min and hold for 150 minutes. Then continue heating to 450°C and hold for 220 minutes. After naturally cooling to room temperature, remove the sample and wash it three times with 5 mL of deionized water and anhydrous ethanol to obtain mesoporous MnNiO. a3 The product has a specific surface area of 10⁸ m². 2 / g.
[0039] Example 4
[0040] Weigh 11.644 g of cobalt nitrate and grind it thoroughly in an agate mortar. Then weigh 10.500 g of citric acid and grind it into a fine powder in the same mortar. Mix the two powders thoroughly, slowly add 7.160 g of 50% manganese nitrate solution while stirring constantly, and disperse the resulting mixture evenly in a porcelain boat. Place the boat in a muffle furnace and heat it to 110°C at a rate of 1°C / min, holding for 150 minutes. Then continue heating to 500°C and holding for 230 minutes. After naturally cooling to room temperature, remove the sample and wash it three times with 5 mL of deionized water and anhydrous ethanol to obtain mesoporous MnCoO. b1 The product has a specific surface area of 76m². 2 / g.
[0041] Example 5
[0042] Weigh 3.745 g of nano-cobalt oxide and grind it thoroughly in an agate mortar. Then weigh 21.000 g of tartaric acid and grind it into a fine powder in the same mortar. Mix the two together thoroughly, slowly add 7.160 g of 50% manganese nitrate solution while stirring constantly, and disperse the resulting mixture evenly in a porcelain boat. Place the boat in a muffle furnace and heat it to 110°C at a rate of 1°C / min, holding for 150 minutes. Then continue heating to 500°C and holding for 230 minutes. After naturally cooling to room temperature, remove the sample and wash it three times with 5 mL of deionized water and anhydrous ethanol to obtain mesoporous MnCoO. b2 The product has a specific surface area of 82m². 2 / g.
[0043] Example 6
[0044] Weigh 1.829 g of cobalt oxalate and grind it thoroughly in an agate mortar. Then weigh 9.450 g of citric acid and grind it into a fine powder in the same mortar. Mix the two together thoroughly, slowly add 7.160 g of 50% manganese nitrate solution while stirring constantly, and disperse the resulting mixture evenly in a porcelain boat. Place the boat in a muffle furnace and heat it to 110°C at a rate of 1°C / min, holding for 150 minutes. Then continue heating to 500°C and holding for 230 minutes. After naturally cooling to room temperature, remove the sample and wash it three times with 5 mL of deionized water and anhydrous ethanol to obtain mesoporous MnCoO. b3 The product has a specific surface area of 91m². 2 / g.
[0045] Example 7
[0046] Weigh 13.026 g of cerium nitrate and grind it thoroughly in an agate mortar. Then weigh 10.500 g of citric acid and grind it into a fine powder in the same mortar. Mix the two together thoroughly, slowly add 7.160 g of 50% manganese nitrate solution while stirring constantly, and disperse the resulting mixture evenly in a porcelain boat. Place the boat in a muffle furnace and heat it to 110°C at a rate of 1°C / min, holding for 150 minutes. Then continue heating to 500°C and holding for 230 minutes. After naturally cooling to room temperature, remove the sample and wash it three times with 5 mL of deionized water and anhydrous ethanol to obtain mesoporous MnCeO. c1 The product has a specific surface area of 93m². 2 / g.
[0047] Example 8
[0048] 1.721 g of nano-cerium oxide was weighed and ground thoroughly in an agate mortar. Then, 13.500 g of tartaric acid was weighed and ground into a fine powder in the same mortar. The two were mixed thoroughly, and 7.160 g of 50% manganese nitrate solution was slowly added dropwise while stirring constantly. The resulting mixture was evenly dispersed in a porcelain boat and placed in a muffle furnace. The temperature was increased to 110°C at a rate of 1°C / min and held for 150 minutes. The temperature was then increased to 500°C and held for 230 minutes. After naturally cooling to room temperature, the sample was removed and washed three times with 5 mL of deionized water and anhydrous ethanol, respectively, to obtain mesoporous MnCeO. c2 The product has a specific surface area of 77m². 2 / g.
[0049] Example 9
[0050] Weigh 7.064 g of cerium oxalate and grind it thoroughly in an agate mortar. Then weigh 6.750 g of tartaric acid and grind it into a fine powder in the same mortar. Mix the two together thoroughly, slowly add 7.160 g of 50% manganese nitrate solution while stirring constantly, and disperse the resulting mixture evenly in a porcelain boat. Place the boat in a muffle furnace and heat it to 110°C at a rate of 1°C / min, holding for 150 minutes. Then continue heating to 500°C and holding for 230 minutes. After naturally cooling to room temperature, remove the sample and wash it three times with 5 mL of deionized water and anhydrous ethanol to obtain mesoporous MnCeO. c3 The product has a specific surface area of 74m². 2 / g.
[0051] Comparative Example 1
[0052] Based on Example 1, without the addition of the auxiliary agent tartaric acid, the remaining processes were the same as in Example 1 to obtain the MnNi-bulk product with a specific surface area of 34 m². 2 / g.
[0053] Comparative Example 2
[0054] Based on Example 4, the calcination process adopted a one-step heating process, that is, heating to 500°C at a heating rate of 1°C / min and holding for 230 minutes, with the remaining processes being the same as in Example 4, to obtain the MnCo-bulk product with a specific surface area of 21 m². 2 / g.
[0055] Comparative Example 3
[0056] Based on Example 7, the calcination process adopted a one-step heating process, that is, heating to 500°C at a heating rate of 1°C / min and holding for 230 minutes, with the remaining processes being the same as in Example 7, to obtain the MnCe-bulk product with a specific surface area of 27 m². 2 / g.
[0057] Table 1 lists the performance of the catalysts in each example for catalytic oxidation of typical VOCs, while Table 2 lists the performance of some literature for oxidation of typical VOCs.
[0058] Table 1 Comparison of catalytic oxidation performance of various catalysts
[0059] Table 2 Performance of typical VOCs oxidation from selected literature
[0060] The above embodiments are used to explain and illustrate the present invention, but not to limit the present invention. Any modifications and changes made to the present invention within the spirit and scope of the claims fall within the protection scope of the present invention.
Claims
1. A method for one-step controllable preparation of mesoporous Mn-based composite metal oxide catalysts, characterized in that, Includes the following steps: (1) Mix the manganese source, the second metal source and the organic auxiliary agent to obtain a mixed precursor; The manganese source is a 50% manganese nitrate solution; the second metal source is a nitrate, oxalate, or nano-oxide of a second metal; the organic auxiliary is tartaric acid or citric acid; (2) The mixed precursor obtained in step (1) is subjected to stepwise calcination: first, it is kept at 110-120℃ for 100-200 minutes, and then kept at 450-700℃ for 200-300 minutes to obtain the primary product; (3) The primary product is washed and dried to obtain the target product, mesoporous Mn-based composite metal oxide catalyst.
2. The method for one-step controllable preparation of mesoporous Mn-based composite metal oxide catalyst according to claim 1, characterized in that, In step (1), the molar ratio of manganese in the manganese nitrate solution, the second metal in the second metal source, and the organic auxiliary is 1:0.3-3:0.3-3.
3. The method for one-step controllable preparation of mesoporous Mn-based composite metal oxide catalysts according to claim 1 or 2, characterized in that, The second metal element in the second metal source is selected from Ni, Co, or Ce.
4. The method according to claim 3, characterized in that, The second metal source is any one of nickel nitrate, nickel oxalate, nano nickel oxide, cobalt nitrate, cobalt oxalate, nano cobalt oxide, cerium nitrate, cerium oxalate, and nano cerium oxide.
5. The method for one-step controllable preparation of mesoporous Mn-based composite metal oxide catalyst according to claim 1, characterized in that, In step (2), the heating rate from room temperature to 110-120℃ is 1℃ / min, and the heating rate from 110-120℃ to 450-700℃ is 1℃ / min.
6. The method for one-step controllable preparation of mesoporous Mn-based composite metal oxide catalyst according to claim 1, characterized in that, In step (3), the washing is performed by alternating between deionized water and anhydrous ethanol.
7. A mesoporous Mn-based composite metal oxide catalyst prepared by any one of the methods described in claims 1 to 6.
8. The catalyst according to claim 7, characterized in that, The catalyst has a specific surface area of 74–108 m². 2 / g.
9. The catalyst according to claim 8, characterized in that, The catalyst has a mesoporous structure with an average pore size of 3.8–10.2 nm.
10. The use of the catalyst as described in claim 9 in the catalytic oxidation of volatile organic compounds.