Exhaust gas treating catalyst and exhaust gas purification apparatus using the same
AssigneesMitsubishi Heavy Industries, Ltd., National Institute of Advanced Industrial Science and Technology
InventorsMasatoshi Katsuki, Shuuji Fujii, Atsushi Ueda, Yusuke Yamada
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Abstract
An exhaust gas treating catalyst further improved in denitrification performance is provided. It is an exhaust gas treating catalyst containing a complex oxide represented by the general formula ABO3, where the A-site is composed of a lanthanoid (La) and barium (Ba), and the B-site is composed of iron (Fe), niobium (Nb) and palladium (Pd).
Claims6
An exhaust gas treating catalyst for reducing nitrogen oxides in an exhaust gas to purify the exhaust gas, the exhaust gas treating catalyst containing a complex oxide represented by a general formula ABO3, where
- the A-site is composed of a lanthanoid (La) and barium (Ba),
- the B-site is composed of iron (Fe), niobium (Nb), and palladium, and
- fulfills {LaxBa(1-x)} {FeyNb(1-y)}(1-z)PdzO3,
- where x is in a range of more than 0.30, but 0.95 or less, y is in a range of 0.07 or more, but 0.94 or less, and z is in a range of 0.01 or more, but 0.10 or less, and
- the complex oxide has such a structure that the barium functions as a NOx storing agent, and the niobium act on the palladium to accelerate NO oxidation and NOx reduction.
An exhaust gas purification method for reducing nitrogen oxides in an exhaust gas containing nitrogen oxides to purify the exhaust gas, the method comprising:
- in a temperature range of 200° C. to 400° C., adjusting the exhaust gas between a lean state where the exhaust gas has a low concentration of carbon monoxide and a high concentration of oxygen and a rich state where the exhaust gas as a high concentration of carbon monoxide and a low concentration of oxygen;
- and
- bringing the exhaust gas into contact with an exhaust gas treating catalyst containing a complex oxide represented by
- {LaxBa(1-x)} {FeyNb(1-y)}(1-z)PdzO3,
- where x is in a range of more than 0.30, but 0.95 or less, y is in a range of 0.07 or more, but 0.94 or less, and z is in a range of 0.01 or more, but 0.10 or less. or more, but 0.94 or less, and z is in a range of 0.01 or more, but 0.10 or less.
Dependencies are inferred from the claim text.