Exhaust gas purifying catalyst and exhaust gas purification method using same

摘要

A catalyst that is not only capable of efficiently treating CO even at a low exhaust gas temperature, but also capable of exerting favorable CO purification efficiency in a low-temperature exhaust gas even in a case of being exposed for a long time to an engine exhaust gas that is a high temperature and contains HC, CO, NOx, water vapor and the like; and an exhaust gas treatment technique are described. The catalyst for purifying exhaust gas contains: a noble metal; an oxide containing as a base material A at least two kinds of elements selected from the group consisting of aluminum, zirconium and titanium; and an oxide containing as a base material B at least one kind of element selected from the group consisting of silicon, cerium, praseodymium and lanthanum; in which the base material A and the base material B satisfy a specific formula.

主权项

1. A catalyst for purifying exhaust gas, comprising:
a noble metal; an oxide comprising as a base material A at least two kinds of elements selected from the group consisting of aluminum, zirconium and titanium; and an oxide comprising as a base material B at least one kind of element selected from the group consisting of silicon, cerium, praseodymium and lanthanum; wherein a base material ratio represented by Equation (X):[Mathematical⁢⁢Expression⁢⁢1]⁢Weight⁢⁢of⁢⁢base⁢⁢material⁢⁢B⁢⁢in⁢⁢terms⁢⁢of⁢⁢oxideWeight⁢⁢in⁢⁢base⁢⁢material⁢⁢A⁢⁢in⁢⁢terms⁢⁢of⁢⁢oxide+Weight⁢⁢of⁢⁢base⁢⁢material⁢⁢B⁢⁢in⁢⁢terms⁢⁢of⁢⁢oxide×100(X)is
(a) 0.01 to 8% by weight when the base material B is silicon, (b) 0.01 to 2% by weight when the base material B is cerium, (c) 0.01 or more to less than 2% by weight when the base material B is praseodymium, and (d) 0.01 to 10% by weight when the base material B is lanthanum,wherein
an oxide of the aluminum as the base material and an oxide of the zirconium as the base material A,are contained, wherein the oxide of the zirconium is 0.1 to 20% by weight when a total weight of the base material A in terms of oxide is set as 100% by weight.