A cobalt-based oxide catalyst, its preparation method and application

Abstract

This invention discloses a cobalt-based oxide catalyst, its preparation method, and its application. The invention involves dispersing cobalt acetate in a high-boiling-point organic solvent, heating it, adding an aqueous carbonate solution, stirring the reaction to obtain a precipitate, and then washing, drying, and calcining it in air to obtain the cobalt-based oxide catalyst. Further, at least one of manganese acetate, cerium acetate, and copper acetate is added to the high-boiling-point organic solvent. The cobalt-based oxide catalyst of this invention, when applied to a formaldehyde catalytic oxidation system, exhibits both high intrinsic performance and abundant active sites. The manganese-doped cobalt-based oxide catalyst can efficiently and stably achieve the complete catalytic decomposition of formaldehyde at 80°C, and its catalytic activity is at an advanced level among currently reported cobalt-based non-precious metal catalysts.

Description

Technical Field

[0001] This invention belongs to the field of catalytic materials technology, specifically relating to a cobalt-based oxide catalyst, its preparation method, and its application. Background Technology

[0002] Formaldehyde is a common indoor air pollutant with strong carcinogenic effects and has been identified as a carcinogen by the World Health Organization. Due to its high chemical reactivity, it reacts with proteins and other biomass in the body, causing biomass denaturation. Long-term exposure to low concentrations of formaldehyde can adversely affect the human sensory, respiratory, and nervous systems, and even lead to serious diseases such as nasopharyngeal carcinoma and leukemia, seriously endangering human health. However, the widespread use of formaldehyde in decoration materials and textile industries makes it an unavoidable presence in daily life. Therefore, developing efficient and safe formaldehyde removal technologies is a major issue concerning human health and safety. Among the various existing formaldehyde removal technologies, catalytic oxidation is recognized as the most promising solution due to its high formaldehyde removal efficiency, long-term energy saving, and environmental friendliness. The core of catalytic oxidation formaldehyde removal technology lies in developing highly active, low-cost formaldehyde oxidation catalysts. Developing safe and efficient formaldehyde oxidation catalysts is key to promoting the practical application of catalytic oxidation formaldehyde removal technology.

[0003] Currently, there are two main types of catalysts commonly used for the catalytic oxidation of formaldehyde: supported noble metal catalysts (such as Pt, Au, Pd, and Ag) and non-noble metal catalysts (such as Co3O4, MnO2, and CeO2). Supported noble metal catalysts have excellent catalytic performance, but their high material cost severely restricts their practical application. In order to reduce the cost of catalyst materials, researchers have increasingly focused on inexpensive and readily available transition metal oxides in recent years. Studies have found that the oxygen vacancy defect structure of oxides has an important influence on the catalytic activity of formaldehyde oxidation. By comprehensively applying modification strategies such as defect engineering, heteroatom doping, and morphology control, researchers have developed a series of defect-structured oxide catalysts. However, in general, existing non-noble metal catalysts generally suffer from low activity and high operating temperature [J. Alloy. Compd. 859(2021)157808], which cannot meet practical needs. Therefore, the design concept and controllable synthesis method of developing highly active non-noble metal catalysts are still key issues that need to be addressed in promoting the practical application of formaldehyde catalytic oxidation technology. Summary of the Invention

[0004] To address the shortcomings and deficiencies of the existing technologies, the primary objective of this invention is to provide a method for preparing cobalt-based oxide catalysts. This invention employs a two-step method combining co-precipitation and heat treatment. First, using an aqueous solution containing hydrated metal acetate as the starting material, an amorphous or nanocrystalline precursor is prepared by co-precipitation. Then, the precursor is obtained through heat treatment to obtain the cobalt-based oxide catalyst. This method utilizes readily available raw materials, is simple to operate, and facilitates mass production, making industrial-scale production possible.

[0005] Another object of the present invention is to provide a cobalt-based oxide catalyst prepared by the above-described method. The catalyst of the present invention is characterized by a high specific surface area and rich in oxygen vacancies, exhibiting both high intrinsic catalytic activity and abundant active sites.

[0006] Another object of the present invention is to provide the application of the above-mentioned cobalt-based oxide catalyst in the catalytic oxidation of formaldehyde, which can efficiently and stably catalyze the oxidative decomposition of formaldehyde at 80°C, and its catalytic activity is at an advanced level among the cobalt-based non-precious metal formaldehyde oxidation catalysts reported to date.

[0007] The objective of this invention is achieved through the following technical solution:

[0008] A method for preparing a cobalt-based oxide catalyst includes the following steps:

[0009] Cobalt acetate was dispersed in a high-boiling-point organic solvent, heated, and then an aqueous carbonate solution was added. The mixture was stirred to react and a precipitate was obtained. After washing, drying, and calcination in air, a cobalt-based oxide catalyst was obtained.

[0010] Preferably, the boiling point of the high-boiling-point organic solvent is greater than 150°C;

[0011] More preferably, the high-boiling-point organic solvent is ethylene glycol.

[0012] Preferably, the carbonate is at least one of sodium carbonate and potassium carbonate.

[0013] Preferably, the cobalt acetate hexahydrate is used.

[0014] Preferably, the concentration of cobalt acetate in the high-boiling-point organic solvent is 0.1-0.4 mol / L;

[0015] Preferably, the concentration of carbonate in the carbonate aqueous solution is 0.1-2.0 mol / L;

[0016] Preferably, the volume ratio of the high-boiling-point organic solvent to the carbonate aqueous solution is 1:1-5.

[0017] Preferably, at least one of manganese acetate, cerium acetate, and copper acetate is also added to the high-boiling-point organic solvent;

[0018] More preferably, the manganese acetate, cerium acetate, and copper acetate are manganese acetate tetrahydrate Mn(CH3COO)2·4H2O, cerium acetate Ce(CH3COO)3, and copper acetate hydrate Cu(CH3COO)2·H2O.

[0019] More preferably, the ratio of the total molar amount of manganese acetate, cerium acetate, and copper acetate in the high-boiling-point organic solvent to the molar amount of cobalt acetate is 1:3-30.

[0020] More preferably, the total concentration of manganese acetate, cerium acetate, and copper acetate in the high-boiling-point organic solvent is 0.01-0.05 mol / L.

[0021] Preferably, the temperature increase is to the temperature of the stirring reaction;

[0022] Preferably, the temperature of the stirring reaction is 80-140℃, and the stirring reaction time is 0.5-2h;

[0023] Preferably, the cleaning refers to cleaning with ultrapure water and anhydrous ethanol respectively;

[0024] Preferably, the drying temperature is 40-100℃ and the time is 0.5-2h;

[0025] Preferably, the calcination temperature is 270-400℃ and the time is 1-4h.

[0026] The cobalt-based oxide catalyst prepared by the above method.

[0027] Preferably, the cobalt-based oxide exists in the form of nanoparticles. The cobalt oxide is a nanoparticle with a size of five to ten nanometers.

[0028] Preferably, the cobalt-based oxide is cobalt tetroxide.

[0029] Preferably, the cobalt-based oxide catalyst has a high specific surface area.

[0030] Preferably, when at least one of manganese acetate, cerium acetate, and copper acetate is added to the high-boiling-point organic solvent, the chemical formula of the cobalt-based oxide catalyst is Co. x M 3-x O4, where 2.25 ≤ x < 3, and M is at least one of Mn, Ce, and Cu. The entry of cations into the cobalt oxide lattice increases the oxygen defect content.

[0031] The above-mentioned cobalt-based oxide catalysts are used in the catalytic oxidation of formaldehyde.

[0032] Preferably, the conditions for the catalytic oxidation of formaldehyde are: initial formaldehyde concentration less than 150 ppm; temperature 40–120 °C; and gas hourly space velocity (GHSV) 40–80 L / g.cat -1 h -1 .

[0033] Further preferred conditions for the catalytic oxidation of formaldehyde are: initial formaldehyde concentration less than 150 ppm; temperature 40–100 °C; and gas hourly space velocity (GHSV) 40–50 L / g. cat -1 h -1 .

[0034] The principle of this invention is as follows: For formaldehyde catalytic oxidation catalysts, the catalyst's activation ability for oxygen molecules and the number of active sites it provides are key factors affecting catalytic performance. Current non-precious metal catalysts often struggle to achieve low-temperature catalytic oxidation of formaldehyde due to weak activation ability for oxygen molecules or insufficient number of active sites. The catalyst provided by this invention introduces heterogeneous ion doping to regulate the number of oxygen vacancies and combines this with nanostructural scaling to increase the catalyst's specific surface area, thereby increasing the number of active sites and improving the catalytic performance of non-precious metal catalysts. This invention employs a two-step synthesis of a cation-doped cobalt oxide catalyst with a high specific surface area using precipitation combined with heat treatment. First, an amorphous or nanocrystalline precursor is obtained through precipitation; subsequently, the heat treatment conditions are controlled to obtain a high specific surface area catalyst rich in oxygen vacancies. In the catalyst of this invention, heterogeneous ions replace cobalt ions, causing lattice expansion that increases the catalyst's oxygen vacancy content. The high specific surface area of ​​the cobalt oxide provides a large number of adsorption and active sites for formaldehyde molecules, and both factors combined improve the catalyst's activity in oxidizing formaldehyde. In summary, the formaldehyde oxidation catalyst provided by this invention possesses both high intrinsic activity and abundant active sites.

[0035] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0036] (1) The cobalt-based oxide catalyst provided by this invention has both intrinsic activity and a large number of active sites. By effectively introducing a large number of oxygen vacancies through ion doping and increasing the specific surface area of ​​the catalyst through nanostructuring, the catalyst’s formaldehyde oxidation activity is effectively improved; complete oxidation and removal of formaldehyde is achieved at 80°C.

[0037] (2) The cobalt-based oxide catalyst obtained in this invention can achieve complete oxidation and removal of formaldehyde at 80℃ and has a high specific mass reaction rate (up to 8.7 μmol g). -1 min -1 Furthermore, this catalyst exhibits excellent stability and moisture resistance in 24-hour isothermal tests and wide humidity range stability tests. Its overall catalytic performance is at an advanced level among currently reported cobalt-based non-precious metal formaldehyde oxidation catalysts.

[0038] (3) The preparation method of the present invention uses readily available raw materials, has a simple process, and is easy to mass-produce. Attached Figure Description

[0039] Figure 1 The Mn-doped cobalt oxide catalyst (denoted as Co) obtained in Example 1 of this invention 2.7 Mn 0.3 X-ray diffraction patterns of O4 and the reference sample.

[0040] Figure 2 The Mn-doped cobalt oxide catalyst (denoted as Co) obtained in Example 1 of this invention 2.7 Mn 0.3 Raman spectra of O4 and the reference sample.

[0041] Figure 3 The catalyst Co obtained in Example 1 of this invention 2.7 Mn 0.3 Transmission electron microscopy (TEM) morphology of O4 (a); selected area electron diffraction pattern (b) and high-resolution electron micrograph (c).

[0042] Figure 4a The catalyst Co obtained in Example 1 of this invention 2.7 Mn 0.3 X-ray photoelectron spectrum of O4 in the O1s region.

[0043] Figure 4b The catalyst Co obtained in Example 1 of this invention 2.7 Mn 0.3 X-ray photoelectron spectrum of O4 in the Co 2p region.

[0044] Figure 4c The catalyst Co obtained in Example 1 of this invention 2.7 Mn 0.3 X-ray photoelectron spectrum of O4 in the Mn 2p region.

[0045] Figure 5a The catalyst Co obtained in Example 1 of this invention 2.7 Mn 0.3 Adsorption-desorption curves of O4 and N2 for reference samples.

[0046] Figure 5b The catalyst Co obtained in Example 1 of this invention 2.7 Mn 0.3 Pore ​​size distribution diagram of O4 and reference sample.

[0047] Figure 6 The catalyst Co obtained in Example 1 of this invention 2.7 Mn 0.3 The graph shows the change in the catalytic oxidation conversion rate of formaldehyde with temperature for O4 and the reference sample.

[0048] Figure 7a The catalyst Co obtained in Example 1 of this invention 2.7 Mn 0.3 The stability test results of O4 are shown in the figure.

[0049] Figure 7b The catalyst Co obtained in Example 1 of this invention 2.7 Mn 0.3 The result of the moisture resistance test of O4 is shown in the figure.

[0050] Figure 8 The Mn, Ce, and Cu-doped cobalt oxide catalysts obtained in Examples 1 and 2 of this invention (referred to as Co) 2.7 Mn 0.3 O4, Co 2.7 Ce 0.3 O4 and Co 2.7 Cu 0.3 X-ray diffraction pattern of O4.

[0051] Figure 9 The catalyst Co obtained in Examples 1 and 2 of this invention 2.7 Mn 0.3 O4, Co 2.7 Ce 0.3 O4 and Co 2.7 Cu 0.3 Diagram showing the formaldehyde catalytic oxidation performance of O4.

[0052] Figure 10 The images show X-ray diffraction patterns of catalysts with different cobalt-manganese ratios obtained in Examples 1 and 3 of this invention.

[0053] Figure 11 The graph shows the formaldehyde catalytic oxidation performance of catalysts with different cobalt-manganese ratios obtained in Examples 1 and 3 of this invention.

[0054] Figure 12 The images show X-ray diffraction patterns of the catalysts obtained at different heat treatment temperatures in Examples 1 and 4 of this invention.

[0055] Figure 13 The graph shows the formaldehyde catalytic oxidation performance of the catalysts obtained at different heat treatment temperatures in Examples 1 and 4 of this invention. Detailed Implementation

[0056] The present invention will be further described in detail below with reference to the embodiments and accompanying drawings, but the implementation methods and protection scope of the present invention are not limited thereto.

[0057] Example 1

[0058] (1) Catalyst preparation:

[0059] Co 2.7 Mn 0.3Synthesis of O4 catalyst: 10 mmol Co(CH3COO)2·4H2O and 1 mmol Mn(CH3COO)2·4H2O were dispersed in 50 mL ethylene glycol. When the temperature reached 120 °C, 100 mL of a pre-prepared 0.5 M Na2CO3 aqueous solution was added to the mixture. The mixture was then magnetically stirred for two hours. The resulting precipitate was thoroughly washed (with ultrapure water and anhydrous ethanol, respectively), vacuum dried (60 °C, 2 h), and then calcined in air (300 °C, 2 h) to obtain the target catalyst Co. 2.7 Mn 0.3 O4.

[0060] Preparation of H-Co3O4: It was prepared by a precipitation combined with heat treatment method. (The text abruptly ends here, seemingly mid-sentence.) 2.7 Mn 0.3 The preparation method of O4 is similar, except that Mn(CH3COO)2·4H2O is not added, while the rest is the same, finally yielding H-Co3O4.

[0061] Preparation of the reference sample MnCO3: It was prepared by a precipitation combined with heat treatment. Compared with the sample Co... 2.7 Mn 0.3 The preparation method for O4 is similar, except that Co(CH3COO)2·4H2O is not added, while everything else remains the same, resulting in the reference sample MnCO3.

[0062] Preparation of reference sample F-Co3O4: It was prepared by precipitation combined with heat treatment. 10 mmol Co(NO3)2·6H2O was dissolved in 20 mL of deionized water at room temperature. 30 mL of pre-prepared 3M NaOH solution was added to the mixed solution and stirred for 4 hours. After the reaction was completed, the precipitate was washed three times each with deionized water and ethanol. Finally, it was heated to 300 °C in air and kept at a constant temperature for 2 hours to obtain F-Co3O4.

[0063] (2) Characterization of the catalyst's phase / structure / elemental chemical state:

[0064] The catalyst Co obtained in this embodiment 2.7 Mn 0.3 The X-ray diffraction, Raman spectrum, and selected area electron diffraction pattern of O4 are shown below. Figure 1 , Figure 2 and Figure 3 As shown in b in the figure. Combined with XRD, Raman spectroscopy, and selected area electron diffraction analysis, it was confirmed that manganese was doped into the cobalt tetroxide lattice. Transmission electron microscopy observation (…) Figure 3 a and Figure 3 c) It was found that cobalt tetroxide has a morphology of 5-10 nm nanoparticles.

[0065] Based on X-ray photoelectron spectroscopy analysis ( Figure 4a , Figure 4b and Figure 4c The resulting catalyst Co 2.7 Mn 0.3 The O1s spectrum of O4 indicates the presence of numerous oxygen vacancies on the catalyst surface; furthermore, the Co 2p and Mn 2p spectra show corresponding low-valence Co atoms. 2+ and Mn 2+ The signal further confirmed the presence of oxygen vacancies on the catalyst surface.

[0066] Based on the N2 adsorption-desorption curve and pore size distribution diagram ( Figure 5a and Figure 5b Firstly, the specific surface area of ​​the H-Co3O4 catalyst is much higher than that of the F-Co3O4 catalyst (95.5 vs 43.3 m²). 2 g -1 The BJH results showed that the F-Co3O4 catalyst had only a small amount of mesoporous structure in the 5–10 nm range, while the H-Co3O4 catalyst had a large number of mesoporous structures concentrated in the 5–20 nm range. Overall, the H-Co3O4 catalyst has a higher specific surface area. The introduction of Mn did not significantly change the specific surface area or pore size distribution of the catalyst. Specifically, Co… 2.7 Mn 0.3 The specific surface area of ​​the O4 catalyst is slightly larger than that of H-Co3O4 (102.2 vs 95.5 m²). 2 g -1 Furthermore, the mesopores of both catalysts are concentrated in the 5-20 nm range, indicating that Mn doping has little effect on the specific surface area and pore size distribution of the catalysts. Based on the above analytical results, it is shown that the method described in this invention successfully synthesizes Mn-doped Co3O4 catalysts with high specific surface area.

[0067] (3) The catalyst Co obtained in this embodiment 2.7 Mn 0.3 O4 catalytic performance test:

[0068] Changes in catalytic activity of catalysts at different temperatures Figure 6 This indicates that, compared with the catalytic activity of reference samples H-Co3O4, F-Co3O4, and MnCO3, Co... 2.7 Mn 0.3 The O4 catalyst exhibits optimal catalytic activity, completely catalytically oxidizing 110 ppm formaldehyde to CO2 and H2O at 80℃, indicating good low-temperature catalytic activity. Furthermore, at 80℃, its mass-to-reaction rate reaches as high as 8.7 μmol / m³. -2 min -1 (H-Co3O4 catalyst is 3.0 μmol m) -2 min-1 The F-Co3O4 catalyst is 0.3 μmol m -2 min -1 The MnCO3 catalyst is 0.1 μmol m -2 min -1 This method outperforms most currently reported cobalt-based non-precious metal catalytic formaldehyde oxidation catalysts. The formaldehyde catalytic oxidation reaction conditions are: a mixture of 110 ppm formaldehyde and high-purity air as the feedstock, with a gas hourly space velocity (GHSV) of 40 L / g. cat -1 h -1 .

[0069] Figure 7a and Figure 7b Co is given 2.7 Mn 0.3 The stability and moisture resistance test results of the O4 catalyst, from Figure 7a It can be seen that under a 24-hour isothermal test (temperature 80℃, humidity 50%), Co 2.7 Mn 0.3 The formaldehyde conversion rate of the O4 catalyst showed only slight fluctuations (87% ± 2%); from Figure 7b It can be seen that the formaldehyde conversion rate is 86±3% under different humidity conditions (temperature 80℃, humidity 20%~70%), and the catalyst activity does not show significant attenuation, indicating that the catalyst has excellent stability and moisture resistance. Formaldehyde catalytic oxidation reaction conditions: the raw material is a mixture of 110ppm formaldehyde and high-purity air, and the gas hourly space velocity is 60Lg. cat -1 h -1 .

[0070] Example 2

[0071] (1) Catalyst preparation:

[0072] In the synthesis method of this embodiment, only Mn(CH3COO)2·4H2O is replaced with Ce(CH3COO)3 and Cu(CH3COO)2·H2O respectively, and the other preparation conditions are the same as in Example 1.

[0073] (2) Phase / structure characterization of the catalyst:

[0074] The catalyst Co obtained in this embodiment x M 3-x X-ray diffraction of O4 as follows Figure 8 As shown. According to XRD analysis, no oxide phases of manganese, cerium, or copper were formed in the prepared catalyst, which means that manganese, cerium, and copper ions may have entered the cobalt tetroxide lattice during the preparation process.

[0075] (3) The target catalyst Co obtained in this embodimentx M 3-x O4 catalytic performance test:

[0076] Changes in catalytic performance of catalysts at different temperatures (see...) Figure 9 This indicates that different cation doping methods have a significant impact on the catalytic oxidation activity of formaldehyde. The catalytic oxidation performance of formaldehyde by various cation dopants, from highest to lowest, is Mn > Ce > Cu. Among them, Co... 2.7 Mn 0.3 The O4 catalyst exhibits optimal catalytic activity, completely catalytically oxidizing 110 ppm formaldehyde to CO2 and H2O at 80 °C, indicating good low-temperature catalytic activity. Furthermore, it demonstrates a high catalytic reaction rate (8.7 μmol m⁻¹). -2 min -1 At 80℃, its activity is superior to most currently reported cobalt-based non-noble metal catalysts. Formaldehyde catalytic oxidation reaction conditions: the feedstock is a mixture of 110 ppm formaldehyde and high-purity air, with a gas hourly space velocity of 40 L / g. cat -1 h -1 .

[0077] Example 3

[0078] (1) Catalyst preparation:

[0079] In this embodiment, the only difference between the cobalt:manganese ratio and the synthesis method is the same as in Example 1. The resulting catalyst is denoted as Co. x Mn 3-x O4 / C.

[0080] (2) Phase / structure characterization of the catalyst:

[0081] The catalyst Co obtained in this embodiment x Mn 3-x X-ray diffraction of O4 / C as follows Figure 10 As shown. According to XRD analysis, the diffraction peaks of samples with different cobalt-manganese feed ratios all matched well with Co3O4. Among them, the prepared catalyst Co x Mn 3-x As the manganese content increases, the diffraction peak intensity of Co3O4 decreases and shifts to a lower angle, indicating that manganese ions are doped into the cobalt tetroxide lattice.

[0082] (3) The catalyst Co obtained in this embodiment x Mn 3-x O4 / C catalytic performance test:

[0083] Changes in catalytic performance of catalysts at different temperatures Figure 11 This indicates that Co xMn 3-x The activity of the O4 / C catalyst in catalyzing the oxidation of formaldehyde is related to the cobalt-manganese ratio, with an optimal ratio of 10:1. A ratio that is too low or too high is detrimental to improving the catalytic activity for formaldehyde oxidation. Co... 2.7 Mn 0.3 The O4 / C catalyst can completely catalytically oxidize 110 ppm formaldehyde to CO2 and H2O at 80℃, indicating that the catalyst has good low-temperature catalytic activity; its activity is superior to most currently reported cobalt-based non-precious metal catalysts. Formaldehyde catalytic oxidation reaction conditions: feedstock is a mixture of 110 ppm formaldehyde and high-purity air, gas hourly space velocity is 40 Lg. cat -1 h -1 .

[0084] Example 4

[0085] (1) Catalyst preparation:

[0086] In this embodiment, the synthesis method is identical to that in Example 1, except that the heat treatment temperatures are changed to 270°C, 300°C, 350°C, and 400°C. The resulting catalyst is denoted as Co. 2.7 Mn 0.3 O4-R, where R is the heat treatment temperature.

[0087] (2) Phase / structure characterization of the catalyst:

[0088] The X-ray diffraction of the catalyst obtained in this embodiment is as follows: Figure 12 As shown in the figure. According to XRD analysis, the diffraction peaks of the samples at different heat treatment temperatures all match well with Co3O4. Furthermore, with increasing calcination temperature, the crystallinity of the samples improved, and the grains became coarser.

[0089] (3) Catalytic performance test of the catalyst obtained in this embodiment:

[0090] Changes in catalytic performance of catalysts at different temperatures Figure 13 This indicates that the catalytic activity of formaldehyde oxidation is related to the calcination temperature of the precursor. The optimal heat treatment temperature is 300℃, while excessively low or high calcination temperatures are detrimental to improving the catalytic activity of formaldehyde oxidation. Among these, Co... 2.7 M 0.3 The O4-300 catalyst exhibited superior formaldehyde catalytic activity compared to the reference sample, completely catalytically oxidizing 110 ppm formaldehyde to CO2 and H2O at 80℃, indicating good low-temperature catalytic activity. Its activity is superior to most currently reported cobalt-based non-precious metal catalysts. Formaldehyde catalytic oxidation reaction conditions: feedstock was a mixture of 110 ppm formaldehyde and high-purity air, with a gas hourly space velocity (GHSV) of 40 L / g. cat -1 h -1.

[0091] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. The application of a cobalt-based oxide catalyst in the catalytic oxidation of formaldehyde, characterized in that, The conditions for the catalytic oxidation of formaldehyde are: an initial formaldehyde concentration greater than or equal to 110 ppm and less than 150 ppm; and a temperature of 80℃. The preparation method of the cobalt-based oxide catalyst includes the following steps: Cobalt acetate and manganese acetate are dispersed in a high-boiling-point organic solvent. After heating, an aqueous carbonate solution is added, and the mixture is stirred to react and obtain a precipitate. This precipitate is then washed, dried, and calcined in air to obtain a cobalt-based oxide catalyst. The high-boiling-point organic solvent has a boiling point greater than 150°C. The carbonate is at least one of sodium carbonate and potassium carbonate. The concentration of cobalt acetate in the high-boiling-point organic solvent is 0.1-0.4 mol / L. The concentration of carbonate in the aqueous carbonate solution is 0.1-2.0 mol / L. The volume ratio of the high-boiling-point organic solvent to the aqueous carbonate solution is 1:1-1:

5. The molar ratio of manganese acetate to cobalt acetate is 1:3-1:

30. The heating is performed to the temperature at which the reaction is stirred. The temperature of the stirring reaction is 80-140℃, and the stirring reaction time is 0.5-2h; The cleaning refers to cleaning with ultrapure water and anhydrous ethanol respectively; the drying temperature is 40-100℃ and the time is 0.5-2h; the calcination temperature is 270-400℃ and the time is 1-4h.

2. The application according to claim 1, characterized in that, The chemical formula of the cobalt-based oxide catalyst is Co. x M 3- x O4, where 2.25 ≤ x < 3, and M is Mn.

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