Purifying catalyst for exhaust gas from internal combustion engine
AssigneesICT Co., Ltd., International Catalyst Technology, Inc.
InventorsEiichi Shiraishi, Shigeyoshi Taniguchi, Takeshi Matsumoto
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Abstract
A purifying catalyst for the exhaust gas from the internal combustion engine of an automobile, for example, is disclosed which excels in the purifying ability in quick response to the atmosphere of the exhaust gas largely varying with changes in the operating condition of the engine involving such phases as idling, acceleration, constant-speed drive, and deceleration. The purifying catalyst contains rhodium, palladium, a cerium compound, and a refractory inorganic oxide as catalytic components carried on a refractory carrier and comprises at least two catalyst layers, namely a catalyst layer containing the cerium compound and a catalyst layer containing palladium.
Claims11
A catalyst for purifying the exhaust gas from an internal combustion engine, said catalyst containing rhodium, palladium, a cerium compound having a BET surface area of not less than 20 m.sup.2 /g and a crystal diameter of not more than 200 A as determined by XRD, and a refractory inorganic oxide as catalyst components, carried on a refractory carrier, in at least a first catalyst superposed on a second inner catalyst layer, said first catalyst layer containing said rhodium, said cerium compound and substantially free of palladium, and said second catalyst layer containing said palladium containing said cerium compound in an amount of not more than 3% by weight as CeO.sub.2 based on the weight of the second catalyst layer, and substantially free of rhodium.
Dependencies are inferred from the claim text.