CATALYST FOR EXHAUST GAS PURIFICATION, AND EXHAUST GAS PURIFICATION METHOD

摘要

PROBLEM TO BE SOLVED: To suppress the granular growth of noble metals using cerium oxide and to prevent lowering of NOx purification rate.

SOLUTION: A noble metal is carried on an oxide carrier containing cerium-based compound oxide particles of an ununiform constitution having a large amount of CeO2on the surface and less in the inner part. The granular growth the noble metal is suppressed by CeO2much existing on the surface. The absolute amount of CeO2is less than that in the conventional case, as the content of CeO2in the inner part is small, causing less capacity of oxygen storing and releasing. This suppresses the consumption of a reducing component in rich spiking, to suppress the lowering of the NOx purification rate.

COPYRIGHT: (C)2004,JPO