THE EFFECT OF OXYGEN STORAGE COMPONENT ON CATALYST THERMAL DURABILITYIN PD CATALYSTS FOR AUTOMOBILE EXHAUST

In Pd catalysts for automobile exhaust, the effect of oxygen storage c omponent (OSC) on NOx conversion after thermal aging has been studied, characterizing structure, oxidate state, O-2 storage capacity and NOx adsorption property. After aging, the higher O-2 storage capacity was achieved and NOx conversion was improved by addition of Zr to CeO2. F rom the various characterizations, it was considered that there were c ubic and tetragonal structure in (Ce, Zr) O-2 and that tetragonal one enhanced the O-2 storage-release ability. As a result, even in O-2 per turbated atmosphere like automotive exhaust, using (Ce, Zr) O-2 as OSC , O-2 on active site might spillover to OSC and active site keep reduc tive state, so NO might absorb and converse to N-2.