Bilayer structured oxygen storage material and preparation method thereof

Abstract

The invention discloses a bilayer structured oxygen storage material and a preparation method thereof. The material is prepared by compounding ceria-zirconia solid solution and gamma-Al2O3 with a great specific surface, wherein the general formula is RexCeyZr1-x-yO2-Al2O3. The preparation method comprises the following steps of: (1) putting lanthanum nitrate solution, cerous nitrate solution, yttrium nitrate solution and zirconium nitrate solution into a container, adding ammonia water into the mixture for precipitation so as to obtain precipitates; (2) adding industrial hydrogen peroxide in the mass of cerium oxide into the precipitates in the step (1) to obtain a ceria-zirconia precursor compound RexCeyZr1-x-y(OH)2; (3) mixing the RexCeyZr1-x-yO2 and the gamma-Al2O3 in a mass ratio of 1:1 and uniformly stirring to obtain a mixture; and (4) firing the mixture in the step (3), decomposing the ceria-zirconia precursor compound RexCeyZr1-x-y (OH)2 into RexCeyZr1-x-yO2, and performing fluid energy milling to obtain the powder oxygen storage material with a bilayer structure. The surfactant adopted by the invention can form interfacial films among ions to avoid the phenomenon of great agglomeration among the ions and to make macropores in the ceria-zirconia solid solution relatively increased, so that the ageing resistance of the oxygen storage material is improved.

Description

technical field [0001] The invention relates to an automobile tail gas purifying agent, which is a double-layer structure oxygen storage material and a preparation method thereof. Background technique [0002] Because automobile exhaust seriously pollutes the atmosphere, so those skilled in the art have proposed many technical solutions aspect how to purify automobile exhaust. At present, the most widely used automobile exhaust gas purification catalyst mainly uses cerium-zirconium solid solution as the oxygen storage material, but it has the following defects, because the CeO in the cerium-zirconium solid solution 2 It is easy to sinter at high temperature, the particles grow up, and the specific surface area decreases, thereby reducing Ce 4+ / C 3+ Oxidation-reduction performance reduces the catalyst's ability to purify automobile exhaust. For this reason, the field uses γ-Al 2 o 3 To solve this defect, however, using the results found that although γ-Al 2 o 3 It has...

AI Technical Summary

Problems solved by technology

At present, the most widely used automobile exhaust gas purification catalyst mainly uses cerium-zirconium solid solution as the oxygen storage material, but it has the following defects, because the CeO in the cerium-zirconium solid solution 2 It is easy to sinter at high temperature, the particles grow up, and the specific surface area decreases, thereby reducing Ce 4+ / C 3+ Oxidation-reduction performance reduces the function of the catalyst to purify automobile exhaust

For this reason, the field uses γ-Al 2 o 3 To solve this defect, however, using the results found that although γ-Al 2 o 3 It has a large specific surface area, which can make the cerium-zirconium solid solution and catalyst active components highly dispersed on its surface, and improve the purification efficiency. However, due to the γ-Al 2 o 3 Physically mixed with cerium-zirconium solid solution, after ball milling, the oxygen storage material and platinum, zirconium, palladium and other active ingredients are impregnated on the surface of the honeycomb carrier. The coating material will be sintered, resulting in the collapse of porous oxide pores, reducing the specific surface area, resulting in a weakened oxygen storage and release capacity, and causing the precious metals dispersed on the surface to be filled into the collapsed pores, thereby reducing the catalytic ability.