| 摘要 |
PROBLEM TO BE SOLVED: To obtain a catalyst capable of selectively reducing NOx for cleaning to N2 at a high conversion rate even in the presence of a vapor by mixing a zeolite powder bearing tin with a manganese oxide powder. SOLUTION: An exhaust gas cleaning catalyst which is useful when a reducing agent is injected into an exhaust gas to clean NOx by reduction, is prepared by mixing a zeolite powder bearing Sn with Mn2 O3 powder. In this case, zeolite is crystalline aluminosilicate expressed by the formula xM2 /n.Al2 O3 .ySiO2 as is well-known, and should preferably have SiO2 /Al2 O3 molar ratio of 10-200. In addition, the surface pore of the zeolite should be small enough to not allow the penetration of a polycyclic aromatic hydrocarbon compound, measuring 10Åor less. Thus, coke is hardly generated, and the structure breakdown and the catalytic activity deterioration by the blocking of pores are prevented from occurring.
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