PURPOSE: To obtain an inexpensive waste gas purification catalyst having high resistance to reducing atmosphere and poisonous components and having high performance by depositing Pd which is less resistant to poisoning to a lower layer part of a catalyst layer and forming a layer of fine powder of perovskite type compound oxide as an upper layer.
CONSTITUTION: After coating a honeycomb carrier consisting of a heat-resistant ceramic and having many pores in the inside with a slurry consisting of activated alumina or HNO3-acidic alumina sol, the carrier is dried and then calcined. Then, Pd having insufficient resistance to several poisons is deposited to a lower layer part of the catalyst layer. Thereafter, fine powder of a perovskite type compound oxide expressed by the general formula ABO3 (wherein A is a rare earth element or an alkaline earth element; B is a transition metal) is deposited together with an alkali additive for the carrier. The catalyst obtd. by this method has high resistance to reducing atmosphere and poisonous components, and purifies waste gas inexpensively and with high performance.
TABATA KENJI
FUKUDA YU
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