High-temperature stability catalyst used for three-effect catalysis

Abstract

The invention discloses a high-temperature stability catalyst used for the catalytic purification of the tail gas of an automobile, which belongs to the technical field of pollution control and relates to a high-temperature stability catalyst capable of keeping three-effect catalysis performance under the condition of high temperature. The high-temperature stability catalyst is characterized in that the prepared high-temperature stability material is a composite oxide solid solution comprising noble metal, cerium oxide, zirconia and an assistant. Compared with a three-effect catalysis material obtained by a traditional immersion method, the catalyst prepared by the invention can ensure the stable existence of noble metal oxide under the condition of high temperature, has favorable catalysis effect and can reach the requirement of the discharge of the tail gas.

Description

technical field [0001] The invention relates to a high-temperature stable catalyst used for catalytic purification of automobile tail gas, in particular to a high-temperature stable catalyst capable of maintaining three-way catalytic performance under high temperature conditions. It is characterized in that the prepared high-temperature stable catalyst adopts the reverse phase microemulsion method, and is formulated with one or more nitrates among Pd, Pt, Rh, Ru, etc., cerium nitrate, zirconium oxynitrate and additive nitrate. The metal salt solution is the water phase, and the microemulsion is composed of a mixed solution of polyoxyethylene glycol octylphenyl ether / n-hexanol / cyclohexane, and ammonia water is used as a precipitant to synthesize Ce 1-x-y-z Zr x A y m z o δ , wherein the precious metal A is one or more of Pd, Pt, Rh, Ru, etc.; M is one of the additives La, Ba, Sr, Bi or Cu. The prepared catalyst is simple in process, has better low-temperature activity and ...

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Problems solved by technology

But in fact, the simple cerium-zirconium solid solution can no longer meet the requirements of the Euro IV standard for automobile exhaust purification catalysts. When the temperature exceeds 1000 ° C, the cerium-zirconium solid solution can no longer exist stably, and it is easy to cause the cerium-zirconium solid solution to break down in the high-temperature oxidation state. phase separation

At present, the impregnation method is mostly used for the loading of noble metals. The phase separation and surface sintering of the cerium-zirconium solid solution make the active centers of the noble metals loaded on the surface sinter and embed, which makes the catalytic activity of the catalyst decrease under high temperature conditions. In order to meet the requirements of automobile exhaust emissions , the research and development of three-way catalysts for automobile exhaust purification with high temperature stability has become a hot spot in recent years

[0004] CN1385239A reports a catalyst for purifying automobile exhaust gas and its preparation process. The catalyst uses aluminum sol as the impregnating stock solution, and directly impregnates the cordierite carrier in the aluminum sol, after drying and roasting, and then impregnating auxiliary agents and precious metal solutions in sequence, and finally obtains Integral three-way catalyst, the catalyst has good low-temperature activity and high-temperature stability, but the process is complex and must go through repeated impregnation and roasting processes, which takes a long time

In recent years, it has been proved to be a very effective method to prepare nanoparticles by using the water core in the inverse microemulsion system as a "microreactor", but there are few reports on the preparation of high-temperature stable catalysts by the inverse microemulsion method.

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