Cerium-zirconium-based composite oxide with core-shell structure, and preparation method thereof

Abstract

The invention relates to a cerium-zirconium-based composite oxide with a core-shell structure, and a preparation method of the cerium-zirconium-based composite oxide. According to the invention, the cerium-zirconium-based composite oxide oxygen storage material with the core-shell structure is prepared through a fractional precipitation method, wherein yttrium post-precipitation is used for segregating yttrium ions (Y<3+>) on the surface of a grain boundary to inhibit the high-temperature sintering phenomenon of the cerium-zirconium-based composite oxide so as to improve the thermal stabilityof the cerium-zirconium-based composite oxide, post-precipitation of a part of zirconium is to enhance the thermal stability, and the yttrium ions have smaller ion radius (0.90 angstrom) and electriccharge quantity, so that the oxygen vacancy formation energy can be reduced, the oxygen storage and release performance can be improved, and the use requirements of catalysts for motor vehicle tail gas purification, industrial waste gas treatment or catalytic combustion and the like can be met.

Description

technical field [0001] The invention relates to catalysts and related fields of preparation thereof, in particular to a core-shell structure cerium-zirconium-based composite oxide and a preparation method thereof. The composite oxide can be used in the fields of motor vehicle tail gas purification, industrial waste gas treatment, catalytic combustion, and the like. Background technique [0002] In recent years, air pollution has attracted much attention. With the increasing number of automobiles in my country and the world, automobile exhaust pollution has become the primary source of urban air pollution, and environmental problems have become increasingly serious. Cerium-zirconium oxygen storage materials are indispensable key catalyst promoter materials in automobile exhaust purification. Especially in the National VI emission stage, cerium-zirconium oxygen storage materials are required to have a sufficiently large specific surface area and a sufficiently high oxygen stor...

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Problems solved by technology

However, the improvement of heat resistance of cerium-zirconium oxides by this method is still limited.

[0004] It is further found that step-by-step precipitation is beneficial to improve the anti-sintering ability. For example, the patent document CN101091914B proposes a method of precipitating zirconium salt and other rare earth metal salts other than cerium, and then precipitating cerium salt. The heat resistance of the specific surface at low temperature (1000 / 3h) is improved, but because the cerium is easy to sinter on the outer layer, the specific surface heat resistance at high temperature after heat treatment at 1100°C for 3 hours is still not ideal (20-22m 2 / g)

Patent document CN 103962120 A proposes to let a part of yttrium salt and other rare earth metal salts and zirconium salts other than yttrium contact with an alkaline substance, and then let the remaining part of the yttrium salt or at least one compound of yttrium and a rare earth metal contact with In contact with alkaline substances, the specific surface heat resistance of the cerium-zirconium composite oxide at high temperature (1000 / 4h) is improved by this method. The anti-sintering performance of the layer is not strong, and the specific surface heat resistance at high temperature after heat treatment at 1100 ° C for 4 hours is still not ideal (15-30m2 / g)

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