A hydrotalcite-like derivative metal oxide catalyst, its preparation method and use
By introducing Cu into the CoAl hydrotalcite layer, a close electronic interaction is formed between CuO and the Co1Al1Ox substrate, which solves the activity and selectivity problems of existing NH3-SCO catalysts and achieves efficient selective catalytic oxidation degradation of NH3.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- DALIAN UNIV OF TECH
- Filing Date
- 2026-05-26
- Publication Date
- 2026-06-23
Smart Images
Figure CN122252186A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of catalyst preparation technology, specifically relating to a hydrotalcite-derived metal oxide catalyst, its preparation method, and its application. Background Technology
[0002] NH3, as an important chemical raw material, is widely used in fertilizers, pharmaceuticals, and printing and dyeing. In recent years, NH3 has been considered a highly promising clean fuel due to its advantages such as being carbon-free and easy to store and transport. However, NH3 itself has an irritating odor and can easily participate in the formation of secondary inorganic aerosols when released into the atmosphere, causing environmental problems. Furthermore, during catalytic oxidation, NH3 may undergo peroxidation reactions, generating more toxic nitrogen oxides, further triggering photochemical smog, which is detrimental to the ecological environment and human health. Therefore, developing efficient and economical NH3 purification technologies is of significant practical importance.
[0003] Currently, NH3 treatment technologies mainly include absorption, adsorption, biofiltration, catalytic combustion, and selective catalytic oxidation (NH3-SCO). Among these, NH3-SCO technology has attracted widespread attention due to its advantages such as simple operation, high treatment efficiency, and no secondary pollution. The core of this technology lies in the catalyst. Existing NH3-SCO catalysts are mainly divided into noble metal catalysts and transition metal oxide catalysts. Although noble metal catalysts (such as Pt, Pd, Au, etc.) have high activity, they are expensive and prone to poisoning and sintering, limiting their industrial application. Transition metal oxide catalysts (such as Cu, Co, Fe, Mn, etc.) have relatively low cost, but catalysts prepared by traditional methods often have small specific surface area, poor dispersion of active components, and insufficient structural stability, resulting in unsatisfactory low-temperature activity and N2 selectivity. Therefore, developing a low-cost, structurally stable, highly active, and excellent N2 selectivity non-noble metal catalyst has become an urgent technical problem to be solved in this field. Summary of the Invention
[0004] This invention aims to provide a hydrotalcite-derived metal oxide catalyst, its preparation method, and its application. This hydrotalcite-derived metal oxide catalyst can promote the adsorption and conversion of NH3 and the generation of N2, and has good application prospects in the selective catalytic oxidation degradation of NH3.
[0005] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: A method for preparing a hydrotalcite-derived metal oxide catalyst includes the following steps: S1. Dissolve cobalt metal salt and aluminum metal salt in deionized water and stir until homogeneous to obtain solution A; S2. Dissolve copper metal salt in deionized water to obtain solution B; S3. Prepare an alkaline precipitant solution C containing hydroxide and carbonate ions; S4. Under heating conditions, add solution C dropwise to solution A while stirring vigorously to adjust the pH to alkaline and maintain this pH value for 1 hour to obtain a mixed solution. S5. Simultaneously titrate solutions B and C into the mixture obtained in S4, adjust the pH to alkaline, carry out the aging reaction, wash, dry, grind the aged product, and calcine it in an oxygen atmosphere to obtain a hydrotalcite-derived metal oxide catalyst.
[0006] Preferably, in S1, the cobalt metal salt is selected from one or more of cobalt nitrate, cobalt chloride, and cobalt sulfate; and the aluminum metal salt is selected from one or more of aluminum nitrate, aluminum chloride, and aluminum sulfate.
[0007] Preferably, in S2, the copper metal salt is selected from one or more of copper nitrate, copper chloride, and copper sulfate.
[0008] Preferably, in S3, the alkaline precipitant solution C is a mixed solution of carbonate and hydroxide.
[0009] Preferably, in S4, the heating temperature is 40-80°C, and the pH is adjusted to 9-10.
[0010] Preferably, in step S5, the pH is adjusted to 9-10, the aging reaction temperature is 40-80°C, and the time is 12-48 hours.
[0011] Preferably, in step S5, the calcination temperature is 400-550℃ and the time is 2-4 hours.
[0012] The present invention also provides a hydrotalcite-derived metal oxide catalyst obtained by the preparation method described above.
[0013] The present invention also provides the application of the aforementioned hydrotalcite-derived metal oxide catalyst in the selective catalytic oxidative degradation of NH3.
[0014] The present invention also provides a method for selective catalytic oxidation degradation of NH3, wherein a mixed gas containing NH3, O2 and Ar is passed through the hydrotalcite-derived metal oxide catalyst.
[0015] Compared with the prior art, the present invention has the following advantages and technical effects: This invention discloses a hydrotalcite-derived metal oxide catalyst, its preparation method, and its application. By introducing Cu into a CoAl hydrotalcite layer, CuO reacts with CoAlO. xA tight electronic interaction is formed between the substrates. This electronic interaction promotes electron transfer between Cu and Co, which is beneficial for the generation of oxygen vacancies and the regulation of the valence state of metal ions. This significantly enhances the adsorption and activation capacity of NH3 and accelerates the selective conversion of intermediate species to N2.
[0016] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description
[0017] Figure 1 The XRD patterns are of the catalysts prepared in Example 1 and Comparative Examples 1-2. Figure 2 The graph shows the NH3 conversion results of the catalysts prepared in Example 1 and Comparative Examples 1-2; Figure 3 The graph shows the N2 yield results of the catalysts prepared in Example 1 and Comparative Examples 1-2.
[0018] Figure 4 The catalyst prepared in Example 1 was in the range of 60,000-150,000 mL·g -1 ·h -1 Activity test diagram under air velocity conditions. Detailed Implementation
[0019] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments.
[0020] Unless otherwise defined, the technical or scientific terms used in this invention shall have the ordinary meaning as understood by one of ordinary skill in the art to which this invention pertains.
[0021] Source of experimental materials: In this invention, unless otherwise specified, all other test materials and instruments are conventional test materials in the field and can be purchased through commercial channels.
[0022] Example 1 A hydrotalcite-derived metal oxide catalyst, prepared by the following steps: S1. Dissolve 1.46g Co(NO3)2·6H2O (0.005mol) and 1.88g Al(NO3)3·9H2O (0.005mol) in 100mL of deionized water and stir until homogeneous to obtain solution A; S2. Dissolve 1.21g Cu(NO3)2·3H2O (0.005mol) in 50mL of deionized water to obtain solution B; S3. Prepare a double-alkali solution containing 0.5M Na2CO3 and 1M NaOH as precipitant C; S4. At 40℃, add solution C dropwise to solution A while magnetically stirring at 200 rpm and adjusting the pH to 10. Maintain this pH value for 1 hour to obtain a mixture. S5. Simultaneously titrate solutions B and C together into the mixture obtained in S4, adjust the pH to 10, and carry out an aging reaction at 40℃ for 24 hours. Wash the aged product with deionized water, dry it overnight at 80℃, grind it, and then calcine it at 550℃ for 3 hours in an oxygen atmosphere to obtain CuO-Co1Al1O. x A hydrotalcite-derived metal oxide catalyst, wherein Co:Cu = 1:1.
[0023] Example 2 The preparation method is the same as in Example 1, except that the Co:Cu ratio is set to 1.8:0.2.
[0024] Example 3 The preparation method is the same as in Example 1, except that the Co:Cu ratio is set to 0.6:1.4.
[0025] Example 4 The preparation method is the same as in Example 1, except that the metal salt solutions are cobalt chloride, copper chloride, and aluminum chloride, respectively.
[0026] Example 5 The preparation method is the same as in Example 1, except that the metal salt solutions are cobalt sulfate, copper sulfate, and aluminum sulfate, respectively.
[0027] Example 6 The preparation method is the same as in Example 1, except that the precipitant is composed of KOH and Na2CO3.
[0028] Example 7 The preparation method is the same as in Example 1, except that the precipitant is composed of NaOH and K2CO3.
[0029] Example 8 The preparation method is the same as in Example 1, except that the aging temperature is 60°C.
[0030] Example 9 The preparation method is the same as in Example 1, except that the aging temperature is 80℃.
[0031] Example 10 The preparation method is the same as in Example 1, except that the calcination temperature is 400℃.
[0032] Comparative Example 1 CuO / Co1Al1O x The catalyst is prepared by the following steps: S1. Dissolve 1.46g Co(NO3)2·6H2O (0.005mol) and 1.88g Al(NO3)3·9H2O (0.005mol) in 100mL of deionized water and stir until homogeneous to obtain solution A; S2. Dissolve 1.21g Cu(NO3)2·3H2O (0.005mol) in 50mL of deionized water to obtain solution B; S3. Prepare a double-alkali solution containing 0.5M Na2CO3 and 1M NaOH as precipitant C; S4. Add solution C dropwise to solution A while magnetically stirring at 200 rpm and adjusting the pH to 10. Perform an aging reaction at 40℃ for 24 hours. Wash the aged product with deionized water, dry at 80℃ overnight, grind, and then calcine at 550℃ for 3 hours in an oxygen atmosphere to obtain Co1Al1O. x ; S5, the Co1Al1O prepared in S4 x The sample was immersed in solution B obtained from S2 for 6 hours, the water was evaporated by rotary evaporation, dried, and calcined at 550℃ for 3 hours, denoted as CuO / Co1Al1O. x .
[0033] Comparative Example 2 Co1Cu1AlO x -m catalyst, the preparation method includes the following steps: S1. Dissolve 1.46g Co(NO3)2·6H2O (0.005mol) and 1.88g Al(NO3)3·9H2O (0.005mol) in 100mL of deionized water and stir until homogeneous to obtain solution A; S2. Prepare a double-alkali solution containing 0.5M Na2CO3 and 1M NaOH as precipitant C; S3. Add solution C dropwise to solution A while magnetically stirring at 200 rpm and adjusting the pH to 10. Perform an aging reaction at 40℃ for 24 hours. Wash the aged product with deionized water, dry at 80℃ overnight, grind, and then calcine at 550℃ for 3 hours in an oxygen atmosphere to obtain Co1Al1O. x ; S4, the Co1Al1O prepared in S3 x Co1Cu1Al1O was physically mixed with CuO at a CuCo molar ratio of 1:1 by mechanical grinding at 200 rpm for 1 hour to obtain Co1Cu1Al1O. x -m.
[0034] The effectiveness of the catalysts provided in Example 1 and Comparative Examples 1-2 was verified.
[0035] The catalysts provided in Example 1 and Comparative Examples 1-2 were characterized by XRD, and the results are as follows: Figure 1 As shown. Both the catalysts in Example 1 and Comparative Examples 1-2 contain CuO and a Co-based spinel structure, but the peak intensities of CuO differ. The catalyst prepared in Example 1 has a lower characteristic peak intensity of CuO compared to the catalysts prepared in Comparative Examples 1-2, indicating that CuO is not simply attached to Co1Al1O. x As expected, CuO is doped into Co1Al1O at a critical state on the surface of the species. x Within the crystal lattice, a portion is exposed on the catalyst surface. This critical transition state promotes the reaction between CuO and Co1Al1O. x The formation of interfaces between substrates promotes electronic interactions.
[0036] The selective catalytic oxidation performance of NH3 was tested in a fixed-bed reactor. The specific experimental protocol is as follows: The catalyst dosage was 200 mg, and the reaction gas composition was 1000 ppm NH3, 5 vol.% O2, with Ar as the equilibrium gas. The gas flow rate was 200 mL / min, and the space velocity was 60000 mL·g. -1 ·h -1 The temperature was increased to 300℃ at a rate of 1℃ / min. The exhaust gas was analyzed using an infrared flue gas analyzer (FGA), and the catalyst activity was determined by the conversion rate of NH3 and the yield of N2. The results are shown in Table 1 and... Figures 2-3 As shown.
[0037] Table 1 Results of selective catalytic oxidation of NH3 activity test
[0038] From Table 1, Figures 2-3 It can be seen that the catalyst provided in Example 1, at a reaction temperature of 240°C, an NH3 concentration of 1000 ppm, and a space velocity of 60000 mL·g, achieves optimal performance. -1 ·h -1 When the catalyst prepared in Comparative Example 1 and Comparative Example 2 was used, complete conversion of NH3 was achieved, and the highest N2 yield of 88.1% was obtained. In contrast, the catalysts prepared in Comparative Example 1 and Comparative Example 2 had lower NH3 conversion rates of 67.0% and 45.1%, respectively, and lower N2 yields of 60.2% and 30.2%, respectively. This indicates that a certain bonding mode between Cu and Co has a promoting effect on the performance of NH3-SCO.
[0039] 200 mg of the catalyst prepared in Example 1 was used to test its NH3 activity in a fixed-bed reactor. The reaction gas consisted of 1000 ppm NH3 and 5 vol.% O2, with Ar as the equilibrium gas. The gas flow rate was 200-500 mL / min, and the space velocity was 60,000-150,000 mL·g. -1 ·h -1 The temperature was initially raised from room temperature to 240°C at a rate of 1°C / min. The reaction tail gas was analyzed using an infrared flue gas analyzer to evaluate the reaction results of the catalyst at different space velocities. Figure 4 As shown, the catalyst can maintain a stable NH3 conversion capacity under different space velocity conditions, but the N2 yield decreases with increasing space velocity. Overall, the catalyst has good prospects for industrial application.
[0040] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.
Claims
1. A method for preparing a hydrotalcite-derived metal oxide catalyst, characterized in that, Includes the following steps: S1. Dissolve cobalt metal salt and aluminum metal salt in deionized water and stir until homogeneous to obtain solution A; S2. Dissolve copper metal salt in deionized water to obtain solution B; S3. Prepare an alkaline precipitant solution C containing hydroxide and carbonate ions; S4. Under heating conditions, add solution C dropwise to solution A while stirring vigorously. Adjust the pH to 9-10 and maintain this pH value for 1 hour to obtain a mixture. S5. Simultaneously titrate solutions B and C into the mixture obtained in S4, adjust the pH to 9-10, carry out the aging reaction, wash, dry, grind the aged product, and calcine it in an oxygen atmosphere to obtain a hydrotalcite-derived metal oxide catalyst.
2. The preparation method according to claim 1, characterized in that, In S1, the cobalt metal salt is selected from one or more of cobalt nitrate, cobalt chloride, and cobalt sulfate; the aluminum metal salt is selected from one or more of aluminum nitrate, aluminum chloride, and aluminum sulfate.
3. The preparation method according to claim 1, characterized in that, In S2, the copper metal salt is selected from one or more of copper nitrate, copper chloride, and copper sulfate.
4. The preparation method according to claim 1, characterized in that, In S3, the alkaline precipitant solution C is a mixed solution of carbonate and hydroxide.
5. The preparation method according to claim 1, characterized in that, In S4, the heating temperature is 40-80℃, and the pH is adjusted to 9-10.
6. The preparation method according to claim 1, characterized in that, In S5, the pH is adjusted to 9-10, and the aging reaction is carried out at a temperature of 40-80°C for 12-48 hours.
7. The preparation method according to claim 1, characterized in that, In S5, the calcination temperature is 400-550℃ and the time is 2-4h.
8. The hydrotalcite-derived metal oxide catalyst obtained by the preparation method according to any one of claims 1-7.
9. The application of the hydrotalcite-derived metal oxide catalyst as described in claim 8 in the selective catalytic oxidative degradation of NH3.
10. A method for selective catalytic oxidative degradation of NH3, characterized in that, A mixture of gas containing NH3, O2 and Ar is passed through the hydrotalcite-derived metal oxide catalyst as described in claim 8.