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US 6,649,563 B2Granted
Ceramic carrier and ceramic catalyst body
AssigneesNippon Soken, Inc., Denso Corporation
InventorsTomohiko Nakanishi, Masanori Yamada, Yosiyasu Andou
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AssigneesNippon Soken, Inc., Denso Corporation
InventorsTomohiko Nakanishi, Masanori Yamada, Yosiyasu Andou
Estimating the term…
A ceramic carrier and ceramic catalyst body used as NOx purification catalysts for lean burn engines, which are inexpensive, exhibit high temperature durability and can maintain their catalytic function for extended periods. The ceramic carrier has a diffusion-inhibiting layer formed on the surface of a cordierite honeycomb structure, to inhibit diffusion of alkali metals, alkaline earth metals, etc. carried as NOx storage materials. The diffusion-inhibiting layer is composed of a ceramic material such as Y2O3, NiO or CeO2 which does not react with alkali metals or alkaline earth metals at temperatures of up to 1000° C. and has a melting point of higher than 1000° C., and the diffusion-inhibiting layer inhibits diffusion of catalyst components such as potassium into the interior to prevent their reaction with cordierite, so that the durability is greatly enhanced without reducing catalytic performance.
A ceramic carrier prepared by forming a diffusion-inhibiting layer which inhibits diffusion of the carried catalyst components from a catalyst-carrying layer to the diffusion-inhibiting layer on a surface of a ceramic honeycomb structure and at least one intermediate layer formed between said ceramic honeycomb structure and said diffusion-inhibiting layer, wherein said diffusion-inhibiting layer is composed of a ceramic material which substantially does not react with said catalyst components under the temperature conditions of use and which has a melting point that is higher than the maximum temperature of use and said intermediate layer comprises a ceramic material with a different thermal expansion coefficient and with a higher melting point than the maximum temperature of use.
Dependencies are inferred from the claim text.