Patent attributes
Provided is an exhaust catalyst that exhibits higher NOX-reducing activities at the time of engine restart while maintaining its catalytic activities during normal traveling. This invention provides an exhaust cleaning catalyst comprising a substrate and a catalyst coating layer that includes CeO2. Catalyst coating layer is constituted in its thickness direction with multiple coating layers. In a top coating layer located at the outermost surface, the CeO2 content in a top coating layer's upstream portion is less than the CeO2 content in a top coating layer's downstream portion; and the CeO2 content in the top coating layer's upstream portion is less than the CeO2 content in a lower coating layer. The CeO2 content per liter of catalyst volume in the entire coating layer is 10 g/L to 30 g/L.
