Preparation method of cerium-zirconium-based oxide solid solution with high specific surface area

Abstract

The invention discloses a preparation method of a cerium-zirconium-based oxide solid solution with high specific surface area. The preparation method comprises the following steps: (1) adding ammonium bicarbonate aqueous solution to a mixed solution of cerium salt, zirconium salt and a salt of other rare earth element except cerium to adjust the pH value of the mixed solution to 4.5-5.0, so as toobtain a mixed precipitation solution; (2) adding the mixed precipitation solution to a basic solution for precipitating, so as to obtain a mixed solution containing a precipitate, wherein the use amount of the basic solution can maintain the pH value of the precipitated mixed solution to 10-11; (3) aging the mixed solution containing the precipitate, collecting the precipitate, washing, then adding a dispersing agent, and pulping; and (4) baking the obtained slurry at 500-800 DEG C for 3-6 hours to obtain the cerium-zirconium-based oxide solid solution. The obtained cerium-zirconium-based oxide solid solution has high specific surface area, excellent oxygen storage and release performances, and can be applied to a cocatalyst or a catalyst carrier of a three-effect catalyst for automobileexhaust.

Description

technical field [0001] The invention relates to a preparation method of a cerium-zirconium-based oxide solid solution with oxygen storage performance. Background technique [0002] Cerium oxide is an important part of the three-way catalyst (TWC) for automobile exhaust, and the cerium ions contained in it generate Ce 3+ and Ce 4+ Oxidation-reduction reaction among them, so as to realize the function of oxygen storage and oxygen release, and contribute to the catalytic conversion of the exhaust gas exhausted by the catalytic conversion of automobile engines operating under different air-fuel ratios. However, pure cerium oxide is easy to sinter at high temperature, resulting in a sharp decline in the performance of oxygen storage and release. By doping an appropriate amount of zirconium into cerium oxide to form a cerium-zirconium-based oxide solid solution, the high-temperature aging resistance of cerium oxide can be greatly improved. Therefore, the research on the synthesi...

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Problems solved by technology

[0004] Because the precipitation pH values ​​of cerium and zirconium ions in the alkaline solution are different, when the positive precipitation method is adopted, it is easy to cause the precipitation and mixing of cerium and zirconium ions to be uneven, and the solid solution level of cerium and zirconium is likely to decrease during the roasting process; In the precipitation method, the cerium and zirconium ions in the precipitate are mixed evenly, but the colloidal particles of the precipitate are too fine, and the surface of the colloidal particles contains a large amount of hydroxyl groups after suction filtration and dehydration, which will easily lead to aggravated sintering during the high-temperature roasting process, thereby reducing the amount of synthesized cerium-zirconium. Oxygen storage and release properties of base oxide solid solutions

Compared with alkali as a precipitant, the cerium-zirconium-based solid solution synthesized by using ammonium bicarbonate as a precipitant is relatively softer, and the sintering degree is much lower than that of the cerium-zirconium-based solid solution synthesized by ammonia water or other alkaline solutions, but due to the precipitation process Medium cerium ions form large particles of crystalline cerium carbonate, while zirconium carbonate is difficult to form a crystalline state, mainly in the form of small amorphous basic zirconium carbonate particles, so due to the low level of ion mixing, it is difficult for cerium and zirconium to form a complete solid dissolved oxide

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