A method for preparing a large specific surface area yttrium oxide
By using tetramethylammonium hydroxide as a precipitant, washing with ethanol, and low-temperature calcination, the problem of easy agglomeration of yttrium oxide was solved, and yttrium oxide with a specific surface area of 100-200 m2/g was prepared, meeting the requirements for high catalytic activity.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- JIANGYIN JIAHUA ADVANCED MATERIAL RESOURCES CO LTD
- Filing Date
- 2023-12-18
- Publication Date
- 2026-06-02
AI Technical Summary
Existing methods for preparing yttrium oxide tend to lead to agglomeration, resulting in insufficient specific surface area and an inability to meet the requirements for high catalytic activity, especially in applications with a specific surface area of 100 m²/g or higher.
Tetramethylammonium hydroxide was used as a precipitant, and a paste was prepared by washing with ethanol and mixing with diethylene glycol monobutyl ether solution. The calcination temperature was controlled at 600-750℃. Anhydrous ethanol was added during ball milling to reduce agglomeration, thus preparing yttrium oxide with a large specific surface area.
The prepared yttrium oxide has a specific surface area of 100-200 m2/g, which meets the requirements for high catalytic activity, and the process is environmentally friendly and energy-saving.
Smart Images
Figure SMS_1
Abstract
Description
Technical Field
[0001] This invention relates to a method for preparing yttrium oxide with a large specific surface area, belonging to the field of catalyst preparation technology. Background Technology
[0002] Yttrium oxide is used for catalytic treatment of automotive exhaust gases, requiring high catalytic activity, which necessitates a large specific surface area. In existing technologies, yttrium oxide is produced by calcining yttrium hydroxide at high temperatures.
[0003] CN108975379A discloses a method for preparing yttrium hydroxide with a large specific surface area, including the following preparation steps: (1) feeding yttrium carbonate; (2) dissolving yttrium carbonate in nitric acid and filtering; (3) mixing yttrium carbonate dissolved in acid with ammonia-urea solution, precipitating and filtering; (4) baking and drying. In this invention, ammonia gas slowly released from urea forms a homogeneous precipitate in the solution, and carbon dioxide released from urea causes the crystal to form a hollow structure during crystal formation, thereby increasing the specific surface area of the prepared yttrium hydroxide. After high-temperature calcination, yttrium hydroxide is converted into yttrium oxide, which further increases the specific surface area, giving yttrium oxide high high-temperature catalytic activity as a catalyst. However, this method uses ammonia precipitation, which easily leads to agglomeration during the preparation of yttrium hydroxide. In the subsequent preparation of yttrium oxide, after calcination at 800°C, the specific surface area only reaches 27 m². 2 / g, in some applications requiring a specific surface area of 100 m² 2 / g is still not applicable. Summary of the Invention
[0004] The purpose of this invention is to solve the problems mentioned in the background section by providing a method for preparing yttrium oxide with a large specific surface area. This method reduces agglomeration and yields yttrium oxide with a specific surface area of 100 m². 2 / g or more.
[0005] The objective of this invention is achieved as follows: a method for preparing yttrium oxide with a large specific surface area, the method comprising the following preparation steps:
[0006] S1. Dissolve the yttrium salt and add tetramethylammonium hydroxide to precipitate it; the yttrium salt is preferably yttrium nitrate or yttrium chloride; the addition rate of the tetramethylammonium hydroxide is 15-25 ml / min.
[0007] S2. Wash with distilled water, control conductivity <2μs / cm, and centrifuge to dehydrate;
[0008] S3. Wash and dehydrate with ethanol 2-3 times;
[0009] S4. Add diethylene glycol monobutyl ether and mix well to form a paste;
[0010] S5. The paste formed after mixing in step S4 is calcined at a low temperature of 600-750℃ for 2-4 hours to form a powder.
[0011] S6. Add anhydrous ethanol to the powder obtained in S5 and ball mill it.
[0012] S7. Drying. Drying temperature 90-105℃, drying time 3-5 hours.
[0013] Compared with the prior art, the present invention has the following advantages:
[0014] This invention discloses a method for preparing yttrium oxide with a large specific surface area. The method involves precipitation with tetramethylammonium hydroxide, whose spatial structure reduces agglomeration. After washing, the oxide is repeatedly washed with ethanol to remove moisture, and then mixed with diethylene glycol monobutyl ether solution to form a paste. During calcination, agglomeration is further reduced, and the calcination temperature is only 600-750℃, making it energy-saving and environmentally friendly. During ball milling, anhydrous ethanol is added, eliminating moisture during the process and further reducing agglomeration. The yttrium oxide prepared by this method has a specific surface area of 100-200 m² / g. 2 / g. Implementation Example 1
[0015] S1. Dissolve yttrium nitrate to prepare 20L of 50g / L yttrium nitrate solution, add 9.5L of 25wt% tetramethylammonium hydroxide precipitate, add at a rate of 20ml / min, stir for 2h until pH=12;
[0016] S2. Wash with distilled water (75L) until conductivity <2μs / cm, then centrifuge to remove water.
[0017] S3, wash 2-3 times with ethanol (15L), then dehydrate;
[0018] S4. Add 1 kg of diethylene glycol monobutyl ether and mix well;
[0019] S5. The paste formed after mixing in step S4 is calcined at a low temperature of 700℃ for 3 hours to form a powder.
[0020] S6. Add anhydrous ethanol to the powder obtained in S5 and ball mill it.
[0021] The product is obtained by drying at 95℃ for 5 hours using S7. Example 2
[0022] S1. Dissolve yttrium chloride to prepare 20L of 50g / L yttrium chloride solution, add 9.5L of 25wt% tetramethylammonium hydroxide precipitate, add at a rate of 22ml / min, stir for 2h, and control the pH to 11;
[0023] S2. Wash with distilled water (75L) until conductivity <2μs / cm, then centrifuge to remove water.
[0024] S3, wash three times with ethanol (15L) to remove distilled water;
[0025] S4. Add diethylene glycol monobutyl ether, with the mass ratio of diethylene glycol monobutyl ether to yttrium oxide being 1:1, and mix thoroughly.
[0026] S5. The paste formed after mixing in step S4 is subjected to low-temperature calcination at a temperature of 650°C for 2.5 hours to form a powder.
[0027] S6. Add anhydrous ethanol to the powder obtained in S5 and ball mill it.
[0028] S7. Dry at 100℃ for 4 hours to obtain the product. Example 3
[0029] S1. Dissolve yttrium nitrate to prepare 20L of 50g / L yttrium nitrate solution, add 9.5L of 25wt% tetramethylammonium hydroxide precipitate, add at a rate of 18ml / min, stir for 3.5h, and control the pH to 10.
[0030] S2. Wash with distilled water (75L) until conductivity <2μs / cm, then centrifuge to remove water.
[0031] S3, wash 2-3 times with ethanol (15L), then dehydrate;
[0032] S4. Add diethylene glycol monobutyl ether, with a mass ratio of diethylene glycol monobutyl ether to yttrium oxide of 2:1, and mix thoroughly.
[0033] S5. The paste formed after mixing in step S4 is subjected to low-temperature calcination at a temperature of 750°C for 2.5 hours to form a powder.
[0034] S6. Add anhydrous ethanol to the powder obtained in S5 and ball mill it.
[0035] The product is obtained by drying at 105℃ for 3.5 hours using S7.
[0036] Comparative Example 1
[0037] This method is based on the method in Example 1, except that the precipitant is replaced with ammonia water, and the other steps are the same.
[0038] Comparative Example 2
[0039] Based on the method of Example 1, the solvent diethylene glycol monobutyl ether used in step S4 before calcination was replaced with ethylene glycol, while the other steps remained the same.
[0040] Comparative Example 3
[0041] Based on the yttrium hydroxide method of Example 1 in CN108975379A, steps S4-S7 are the same as in Example 1.
[0042] Comparative Example 4
[0043] Step S3 is removed; the other steps are the same as in Example 1.
[0044] Comparative Example 5
[0045] In step S6, water is added to the powder instead of anhydrous ethanol, and the other steps are the same as in Example 1.
[0046] Comparative Example 6
[0047] In step S5, the burning temperature is 900℃ and the burning time is 2h. Other steps are the same as in Example 1.
[0048] The specific surface area of yttrium oxide prepared in Examples 1-3 and Comparative Examples 1-6 was tested, and the test results are shown in Table 1.
[0049] The specific surface area was tested using a NOVA fully automated specific surface area and porosity analyzer at 77K using nitrogen as the adsorbent gas. Before the nitrogen adsorption-desorption test, the samples needed to be degassed at 250℃ for 1-2 hours to remove moisture and air from the material pores. The specific surface area was calculated using the multi-point BET method.
[0050] Table 1
[0051]
[0052] In addition to the above embodiments, the present invention also includes other embodiments. All technical solutions formed by equivalent transformation or equivalent substitution should fall within the protection scope of the claims of the present invention.
Claims
1. A method for preparing yttrium oxide with a large specific surface area, characterized in that: The yttrium oxide has a specific surface area of 100-200 m². 2 / g, the method includes the following preparation steps: S1. Dissolve the yttrium salt and add tetramethylammonium hydroxide to precipitate it; S2. Wash with distilled water and centrifuge to remove water; S3. Wash with ethanol and dehydrate; S4. Add diethylene glycol monobutyl ether and mix well to form a paste; S5. The paste formed after mixing in step S4 is calcined at a low temperature to form a powder. S6. Add anhydrous ethanol to the powder obtained in S5 and ball mill it. S7. Drying; The S5 step involves burning at a temperature of 600-750℃ for 2-4 hours.
2. The method for preparing yttrium oxide with a large specific surface area according to claim 1, characterized in that: The yttrium salt is either yttrium nitrate or yttrium chloride.
3. The method for preparing yttrium oxide with a large specific surface area according to claim 1, characterized in that: In step S2, the conductivity after final washing is controlled to be <2μs / cm.
4. The method for preparing yttrium oxide with a large specific surface area according to claim 1, characterized in that: In step S7, the drying temperature is 90-105℃ and the drying time is 3-5 hours.
5. The method for preparing yttrium oxide with a large specific surface area according to claim 1, characterized in that: The feeding rate of the tetramethylammonium hydroxide is 15-25 ml / min.
6. The method for preparing yttrium oxide with a large specific surface area according to claim 1, characterized in that: In step S1, the final pH after precipitation is controlled to be ≥10.