A cobalt-cerium solid solution catalyst, a preparation method and application thereof

Abstract

The present application relates to a kind of cobalt cerium solid solution catalyst and its preparation method and application, the preparation method includes the following steps: after mixing cobalt source, cerium source and alkali source, mixed solution is obtained, the pH value of the mixed solution is adjusted, cobalt cerium solid solution catalyst precursor is prepared using coprecipitation method or hydrothermal method, then in turn washing, drying and calcining, the cobalt cerium solid solution catalyst is obtained.The present application prepares a kind of cobalt cerium solid solution catalyst, can realize catalytic decomposition of nitrous oxide, can also realize catalytic oxidation of methanol.Cobalt cerium solid solution special electronic structure and surface properties, make it have different types of catalytic active sites, and then realize the catalytic decomposition and catalytic oxidation of different substances.Cobalt cerium solid solution catalyst prepared by the present application not only has excellent catalytic performance, but also has low preparation cost, which is beneficial to large-scale batch production.

Description

Technical Field

[0001] This invention relates to the field of catalyst technology, specifically to a solid solution catalyst, its preparation method, and its application, and more particularly to a cobalt-cerium solid solution catalyst, its preparation method, and its application. Background Technology

[0002] Currently, nitrous oxide is a greenhouse gas with a global warming potential more than 300 times that of carbon dioxide. At the same time, nitrous oxide also has a destructive effect on the ozone layer, and it is very stable in the stratosphere with a long average lifetime.

[0003] Catalytic decomposition of nitrous oxide into nitrogen and oxygen is the most direct and economical method for eliminating nitrous oxide. Since the nitrous oxide decomposition reaction is exothermic, it is generally carried out at relatively high temperatures. CN106391037A discloses a preparation process for a catalyst for high-temperature catalytic decomposition of N2O. This invention employs a co-precipitation method, where the active component and the precursor of the support material react with the precipitant and precipitate together. The active component and the support are intertwined, resulting in better dispersion and stability of the active component. The active component and the precipitate are then calcined together at 1000℃-1300℃, further ensuring better heat resistance and reduced loss of the catalyst's active component. Furthermore, the catalyst's catalytic efficiency is higher, more stable, and its service life is longer. However, the catalyst used in this invention requires high-temperature calcination, resulting in high costs and hindering large-scale mass production.

[0004] Methanol is an oxygen-containing volatile organic compound that poses a direct threat to human health and is a precursor to ozone and haze formation, easily leading to air pollution. Catalytic oxidation of methanol is a commonly used technology for methanol removal, offering advantages such as high efficiency and minimal secondary pollution. However, current technologies often employ precious metal catalysts for methanol catalytic oxidation, which are expensive.

[0005] In existing technologies, catalysts exhibit selective catalytic sites, making it difficult to achieve a single catalyst that can efficiently catalyze the oxidation of both nitrous oxide and methanol. Furthermore, catalysts that catalyze the decomposition of nitrous oxide or the oxidation of methanol alone generally suffer from high processing costs and high prices. Therefore, how to prepare a catalyst at low cost that can efficiently catalyze both the decomposition of N₂O and the oxidation of methanol has become an urgent problem to be solved. Summary of the Invention

[0006] To address the aforementioned technical problems, this invention provides a cobalt-cerium solid solution catalyst, its preparation method, and its applications. This invention, by preparing a cobalt-cerium solid solution catalyst, can achieve both the catalytic decomposition of nitrous oxide and the catalytic oxidation of methanol. The unique electronic structure and surface properties of cobalt-cerium solid solutions endow them with different types of catalytically active sites, thereby enabling the catalytic decomposition and oxidation of various substances. The cobalt-cerium solid solution catalyst prepared by this invention not only exhibits excellent catalytic performance but also has low preparation cost, which is beneficial for large-scale mass production.

[0007] To achieve this objective, the present invention adopts the following technical solution:

[0008] In a first aspect, the present invention provides a method for preparing a cobalt-cerium solid solution catalyst, the method comprising the following steps: mixing a cobalt source, a cerium source and an alkaline source to obtain a mixed solution, adjusting the pH value of the mixed solution, preparing a cobalt-cerium solid solution catalyst precursor by co-precipitation or hydrothermal method, and then sequentially washing, drying and calcining to obtain the cobalt-cerium solid solution catalyst.

[0009] This invention provides a cobalt-cerium solid solution catalyst capable of both catalytic decomposition of nitrous oxide and catalytic oxidation of methanol. The unique electronic structure and surface properties of the cobalt-cerium solid solution endow it with different types of catalytic sites, thereby enabling the catalytic decomposition and oxidation of various substances. The cobalt-cerium solid solution catalyst prepared by this invention not only exhibits excellent catalytic performance but also boasts low preparation cost, facilitating large-scale mass production.

[0010] Preferably, the cobalt source includes any one or a combination of at least two of cobalt nitrate, cobalt chloride, or cobalt acetate. Typical but non-limiting combinations include a combination of cobalt nitrate and cobalt chloride, or a combination of cobalt nitrate, cobalt chloride, and cobalt acetate.

[0011] Preferably, the cerium source includes any one or a combination of at least two of cerium nitrate, cerium chloride, or cerium acetate. Typical but non-limiting combinations include a combination of cerium nitrate and cerium chloride, or a combination of cerium nitrate, cerium chloride, and cerium acetate.

[0012] Preferably, the molar ratio of the cobalt source to the cerium source is (1-5):(1-5), for example, it can be 1:5, 2:1, 3:2, 1:1, 1:2, 2:5 or 5:1, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0013] This invention modulates the electronic structure and surface properties of cobalt-cerium solid solutions by further adjusting the molar ratio of cobalt and cerium sources. Different molar ratios of cobalt and cerium sources result in varying dispersions of the two sources within the solid solution, leading to differences in electron transfer between cobalt and cerium, which in turn affects the activity of the catalytic sites. Within a preferred molar ratio range, the cobalt-cerium solid solution catalyst of this invention exhibits excellent catalytic activity, further enhancing its catalytic activity in the decomposition of nitrous oxide and its catalytic activity in the oxidation of methanol.

[0014] Preferably, the alkali source includes any one or a combination of at least two of potassium carbonate, sodium carbonate, potassium hydroxide, or ammonia water. Typical but non-limiting combinations include a combination of potassium carbonate and sodium carbonate, or a combination of sodium carbonate, potassium hydroxide, and ammonia water.

[0015] Preferably, the mixing method includes stirring.

[0016] Preferably, the pH value of the mixed solution is 8-10, for example, it can be 8, 8.5, 9, 9.5 or 10, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0017] Preferably, the precipitation temperature of the coprecipitation method is 20℃-40℃, for example, it can be 20℃, 25℃, 30℃, 35℃, 38℃ or 40℃, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0018] Preferably, the precipitation time of the co-precipitation method is 2h-12h, for example, it can be 2h, 4h, 6h, 8h, 10h or 12h, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0019] This invention improves the uniformity and specific surface area of ​​the cobalt-cerium solid solution catalyst by controlling the precipitation temperature and precipitation time of the co-precipitation method, thereby enhancing the catalytic activity of the catalyst. Within the preferred precipitation temperature and precipitation time range, the cobalt-cerium solid solution catalyst exhibits high activity, which can further enhance its catalytic activity in the decomposition of nitrous oxide and its catalytic activity in the oxidation of methanol.

[0020] Preferably, the hydrothermal temperature of the hydrothermal method is 100℃-200℃, for example, it can be 100℃, 120℃, 140℃, 160℃, 180℃ or 200℃, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0021] Preferably, the hydrothermal time of the hydrothermal method is 20h-28h, for example, it can be 20h, 22h, 24h, 26h, 27h or 28h, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0022] This invention improves the uniformity and specific surface area of ​​the cobalt-cerium solid solution catalyst by controlling the hydrothermal temperature and time of the hydrothermal method, thereby enhancing the catalytic activity of the catalyst. Within the preferred range of hydrothermal temperature and time, the cobalt-cerium solid solution catalyst exhibits high activity, which can further enhance its catalytic activity in the decomposition of nitrous oxide and its catalytic activity in the oxidation of methanol.

[0023] Preferably, the endpoint of the washing is to make the pH value of the washing solution 6.5-7.5, for example, 6.5, 6.9, 7, 7.2 or 7.5, but not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0024] Preferably, the detergent used for washing includes deionized water and / or ethanol.

[0025] Preferably, the drying and heat preservation temperature is 80℃-120℃, for example, it can be 80℃, 90℃, 100℃, 110℃, 115℃ or 120℃, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0026] Preferably, the drying and heat preservation time is 12h-16h, for example, it can be 12h, 13h, 14h, 15h, 15.5h or 16h, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0027] Preferably, the calcination holding temperature is 300℃-600℃, for example, it can be 300℃, 350℃, 400℃, 450℃, 500℃ or 600℃, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0028] Preferably, the calcination holding time is 2h-4h, for example, it can be 2h, 2.5h, 3h, 3.5h, 3.8h or 4h, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0029] This invention further improves the crystallinity of cobalt-cerium solid solution by controlling the calcination temperature and time, thereby optimizing the electronic structure and surface properties of the cobalt-cerium solid solution. At the preferred calcination temperature and time, the cobalt-cerium solid solution catalyst of this invention exhibits excellent catalytic activity, not only further enhancing its catalytic activity in the decomposition of nitrous oxide but also its catalytic activity in the oxidation of methanol.

[0030] As a preferred technical solution of the present invention, the preparation method includes the following steps:

[0031] (1) After mixing the cobalt source, cerium source and alkali source in proportion, a mixed solution is obtained.

[0032] (2) Adjust the pH value of the mixed solution and prepare the cobalt-cerium solid solution catalyst precursor by co-precipitation or hydrothermal method; the pH value of the mixed solution is 8-10; the precipitation temperature of the co-precipitation method is 20℃-40℃ and the precipitation time of the co-precipitation method is 2h-12h; the hydrothermal temperature of the hydrothermal method is 100℃-200℃ and the hydrothermal time of the hydrothermal method is 20h-28h.

[0033] (3) The cobalt-cerium solid solution catalyst precursor is sequentially filtered, washed, dried and calcined to obtain the cobalt-cerium solid solution catalyst; the washing agent includes deionized water and / or ethanol, and the washing endpoint is to make the pH value of the washing solution 6.5-7.5; the drying holding temperature is 80℃-120℃, the drying holding time is 12h-16h, the calcination holding temperature is 300℃-600℃, and the calcination holding time is 2h-4h.

[0034] In a second aspect, the present invention provides a cobalt-cerium solid solution catalyst, which is prepared by the preparation method described in the first aspect.

[0035] Thirdly, the present invention provides an application of the cobalt-cerium solid solution catalyst as described in the second aspect, wherein the cobalt-cerium solid solution catalyst is used for the catalytic decomposition of N2O or the catalytic oxidation of methanol.

[0036] Compared with the prior art, the present invention has at least the following beneficial effects:

[0037] (1) The present invention prepares a cobalt-cerium solid solution catalyst that can achieve both catalytic decomposition of nitrous oxide and catalytic oxidation of methanol.

[0038] (2) This invention utilizes the special electronic structure and surface properties of cobalt-cerium solid solution to give it different types of catalytic active sites, thereby achieving catalytic decomposition and catalytic oxidation of different substances.

[0039] (3) The cobalt-cerium solid solution catalyst prepared by the present invention not only has excellent catalytic performance, but also has low preparation cost, which is conducive to large-scale mass production. Detailed Implementation

[0040] To facilitate understanding of the present invention, the following embodiments are provided. Those skilled in the art should understand that these embodiments are merely illustrative and should not be construed as limiting the scope of the invention.

[0041] Example 1

[0042] This embodiment provides a method for preparing a cobalt-cerium solid solution catalyst, the method comprising the following steps:

[0043] (1) After mixing cobalt nitrate, cerium nitrate and potassium carbonate in proportion, a mixed solution is obtained; the molar ratio of cobalt nitrate and cerium nitrate is 1:1;

[0044] (2) Adjust the pH value of the mixed solution and prepare the cobalt-cerium solid solution catalyst precursor by co-precipitation method; the pH value of the mixed solution is 9.5; the precipitation temperature of the co-precipitation method is 20℃ and the precipitation time of the co-precipitation method is 3h;

[0045] (3) The cobalt-cerium solid solution catalyst precursor is sequentially filtered, washed, dried and calcined to obtain the cobalt-cerium solid solution catalyst; the washing agent includes deionized water, and the washing endpoint is to make the pH value of the washing liquid 7; the drying holding temperature is 100℃, the drying holding time is 12h, the calcination holding temperature is 400℃, and the calcination holding time is 3h.

[0046] Example 2

[0047] This embodiment provides a method for preparing a cobalt-cerium solid solution catalyst, the method comprising the following steps:

[0048] (1) After mixing cobalt acetate, cerium acetate and sodium carbonate in proportion, a mixed solution is obtained; the molar ratio of cobalt acetate to cerium acetate is 5:1;

[0049] (2) Adjust the pH value of the mixed solution and prepare the cobalt-cerium solid solution catalyst precursor by hydrothermal method; the pH value of the mixed solution is 10; the hydrothermal temperature of the hydrothermal method is 170℃ and the hydrothermal time of the hydrothermal method is 24h.

[0050] (3) The cobalt-cerium solid solution catalyst precursor is sequentially filtered, washed, dried and calcined to obtain the cobalt-cerium solid solution catalyst; the washing agent includes ethanol, and the washing endpoint is to make the pH value of the washing solution 6.5; the drying temperature is 80°C and the drying time is 16h; the calcination temperature is 600°C and the calcination time is 2h.

[0051] Example 3

[0052] This embodiment provides a method for preparing a cobalt-cerium solid solution catalyst, the method comprising the following steps:

[0053] (1) After mixing cobalt chloride, cerium chloride and potassium hydroxide in proportion, a mixed solution is obtained; the molar ratio of cobalt chloride and cerium chloride is 1:5;

[0054] (2) Adjust the pH value of the mixed solution and prepare the cobalt-cerium solid solution catalyst precursor by co-precipitation or hydrothermal method; the pH value of the mixed solution is 8; the precipitation temperature of the co-precipitation method is 40℃ and the precipitation time of the co-precipitation method is 12h;

[0055] (3) The cobalt-cerium solid solution catalyst precursor is sequentially filtered, washed, dried and calcined to obtain the cobalt-cerium solid solution catalyst; the washing agent includes deionized water, and the washing endpoint is to make the pH value of the washing solution 7.5; the drying temperature is 120°C and the drying time is 12h; the calcination temperature is 300°C and the calcination time is 4h.

[0056] Example 4

[0057] The only difference between this embodiment and Embodiment 1 is that, except that the molar ratio of cobalt nitrate and cerium nitrate in step (1) is 1:5.5, everything else is the same as in Embodiment 1.

[0058] Example 5

[0059] The only difference between this embodiment and Embodiment 1 is that, except that the molar ratio of cobalt nitrate and cerium nitrate in step (1) is 5.5:1, everything else is the same as in Embodiment 1.

[0060] Example 6

[0061] The only difference between this embodiment and Embodiment 1 is that, except that the alkali source used in step (1) is changed from potassium carbonate to sodium carbonate, everything else is the same as in Embodiment 1.

[0062] Example 7

[0063] The only difference between this embodiment and Example 1 is that, except that the alkali source used in step (1) is replaced by potassium hydroxide instead of potassium carbonate, everything else is the same as in Example 1.

[0064] Example 8

[0065] The only difference between this embodiment and Embodiment 1 is that, except that the alkaline source used in step (1) is replaced with ammonia instead of potassium carbonate, everything else is the same as in Embodiment 1.

[0066] Example 9

[0067] The only difference between this embodiment and Embodiment 1 is that, except for the pH value of the mixed solution in step (2) being 7.5, everything else is the same as in Embodiment 1.

[0068] Example 10

[0069] The only difference between this embodiment and Embodiment 1 is that, except for the pH value of the mixed solution described in step (2) being 10.5, everything else is the same as in Embodiment 1.

[0070] Example 11

[0071] The only difference between this embodiment and embodiment 2 is that, except that the hydrothermal temperature in step (2) is 95°C, everything else is the same as in embodiment 2.

[0072] Example 12

[0073] The only difference between this embodiment and embodiment 2 is that, except that the hydrothermal temperature in step (2) is 205°C, everything else is the same as in embodiment 2.

[0074] Example 13

[0075] The only difference between this embodiment and embodiment 1 is that, except that the holding temperature for roasting in step (3) is 250°C, everything else is the same as in embodiment 1.

[0076] Example 14

[0077] The only difference between this embodiment and embodiment 1 is that, except that the holding temperature for roasting in step (3) is 650°C, everything else is the same as in embodiment 1.

[0078] Comparative Example 1

[0079] The only difference between this comparative example and Example 1 is that, except for step (1), only cobalt nitrate is added instead of cerium nitrate, everything else is the same as in Example 1.

[0080] Comparative Example 2

[0081] The only difference between this comparative example and Example 1 is that, except for step (1), only cerium nitrate is added and cobalt nitrate is not added, everything else is the same as Example 1.

[0082] Comparative Example 3

[0083] The only difference between this comparative example and Example 2 is that, except for step (1), only cobalt nitrate is added instead of cerium nitrate, everything else is the same as in Example 2.

[0084] Comparative Example 4

[0085] The only difference between this comparative example and Example 2 is that, except for step (1) which only uses cerium nitrate and does not add cobalt nitrate, everything else is the same as in Example 2.

[0086] Test methods

[0087] The cobalt-cerium solid solution catalysts prepared in Examples 1-14 and Comparative Examples 1-4 were placed in a quartz tube with a diameter of 6 mm. 1000 ppm of nitrous oxide gas (nitrogen as the balance gas) and 200 ppm of methanol (air as the balance gas) were introduced into the tube, respectively. The gas hourly space velocity (WHSV) was 30000 ml·h. -1 g -1 The reaction was carried out continuously under normal pressure by controlling the heating furnace program. The temperatures required for the catalytic decomposition of 90% nitrous oxide and the catalytic oxidation of 90% methanol were recorded and the results are recorded in Table 1.

[0088] Table 1

[0089]

[0090]

[0091] The test results show that:

[0092] (1) As can be seen from Examples 1-14 and Comparative Examples 1-4, this invention, by preparing a cobalt-cerium solid solution catalyst, can achieve both the catalytic decomposition of nitrous oxide and the catalytic oxidation of methanol. The unique electronic structure and surface properties of the cobalt-cerium solid solution give it different types of catalytic active sites, thereby enabling the catalytic decomposition and catalytic oxidation of different substances. The cobalt-cerium solid solution catalyst prepared by this invention not only has excellent catalytic performance but also low preparation cost, which is conducive to large-scale mass production.

[0093] (2) As can be seen from Examples 1 and 4-5, by further adjusting the molar ratio of cobalt source and cerium source, the present invention can not only further reduce the temperature of catalyst catalytic decomposition of N2O, but also further reduce the temperature of catalyst catalytic oxidation of methanol, thereby further improving the catalytic effect of the catalyst.

[0094] (3) As can be seen from Examples 1 and 6-8, by further selecting the type of alkali source, the present invention can not only further reduce the temperature of the catalyst for catalytic decomposition of N2O, but also further reduce the temperature of the catalyst for catalytic oxidation of methanol, thereby further improving the catalytic effect of the catalyst.

[0095] (4) As can be seen from Examples 1 and 9-10, by further adjusting the pH value of the mixed solution, the present invention can not only further reduce the temperature of the catalyst for catalytic decomposition of N2O, but also further reduce the temperature of the catalyst for catalytic oxidation of methanol, thereby further improving the catalytic effect of the catalyst.

[0096] (5) As can be seen from Examples 2 and 11-12, by further adjusting the hydrothermal temperature of the hydrothermal method, the present invention can not only further reduce the temperature of the catalyst for catalytic decomposition of N2O, but also further reduce the temperature of the catalyst for catalytic oxidation of methanol, thereby further improving the catalytic effect of the catalyst.

[0097] (6) As can be seen from Examples 1 and 13-14, by further controlling the calcination temperature, the present invention can not only further reduce the temperature of the catalyst for catalytic decomposition of N2O, but also further reduce the temperature of the catalyst for catalytic oxidation of methanol, thereby further improving the catalytic effect of the catalyst.

[0098] In summary, this invention provides a cobalt-cerium solid solution catalyst that can catalyze both the decomposition of nitrous oxide and the catalytic oxidation of methanol. The unique electronic structure and surface properties of the cobalt-cerium solid solution endow it with different types of catalytically active sites, thereby enabling the catalytic decomposition and oxidation of various substances. The cobalt-cerium solid solution catalyst prepared by this invention not only exhibits excellent catalytic performance but also boasts low preparation cost, facilitating large-scale mass production.

[0099] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A method for preparing a cobalt-cerium solid solution catalyst, characterized in that, The preparation method includes the following steps: A mixed solution was obtained by mixing cobalt source, cerium source and potassium carbonate. The pH of the mixed solution was adjusted to 9.5-10. A cobalt-cerium solid solution catalyst precursor was prepared by co-precipitation method. The precursor was then washed, dried and calcined to obtain the cobalt-cerium solid solution catalyst. The molar ratio of the cobalt source to the cerium source is 1:1; The precipitation temperature for the co-precipitation method is 20℃-38℃; The roasting temperature is 400℃-600℃.

2. The preparation method according to claim 1, characterized in that, The cobalt source includes any one or a combination of at least two of cobalt nitrate, cobalt chloride, or cobalt acetate.

3. The preparation method according to claim 1, characterized in that, The cerium source includes any one or a combination of at least two of cerium nitrate, cerium chloride, or cerium acetate.

4. The preparation method according to claim 1, characterized in that, The mixing method includes stirring.

5. The preparation method according to claim 1, characterized in that, The precipitation time for the co-precipitation method is 2h-12h.

6. The preparation method according to claim 1, characterized in that, The endpoint of the washing process is to bring the pH of the washing solution to 6.5-7.

5.

7. The preparation method according to claim 1, characterized in that, The detergent used for washing includes deionized water and / or ethanol.

8. The preparation method according to claim 1, characterized in that, The drying process is carried out at a temperature of 80℃-120℃.

9. The preparation method according to claim 1, characterized in that, The drying and heat preservation time is 12h-16h.

10. The preparation method according to claim 1, characterized in that, The roasting time is 2-4 hours.

11. A cobalt-cerium solid solution catalyst, characterized in that, The cobalt-cerium solid solution catalyst was prepared using the preparation method described in any one of claims 1-10.

12. An application of the cobalt-cerium solid solution catalyst as described in claim 11, characterized in that, The cobalt-cerium solid solution catalyst is used for the catalytic decomposition of N2O or the catalytic oxidation of methanol.

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