COPPER-BASED AUTO EXHAUST OXIDATION CATALYSTS: DEACTIVATION AND PHYSICAL ATTRITION

ADVERSE AGING EFFECTS, SUCH AS DEACTIVATION AND PHYSICAL ATTRITION, ON COPPER-BASED AUTO EXHAUST OXIDATION CATALYSTS HAVE BEEN INVESTIGATED BY STUDIES OF CATALYSTS COMPRISING OXIDES OF COPPER ON ALUMINA. EXPOSURE TO CYCLIC OXIDATION REDUCTION CAN CAUSE PHYSICAL ATTRITION OF POORLY DISPERSED COOPER-BASED CATALYSTS IN THE PRESENCE OR ABSENCE OF HALIDES. THIS CHEMICALLY INDUCED ATTRITION PROCESS IS RELATIVELY INDEPENDENT OF THE HARDNESS OF THE CATALYST SUPPORT. HOWEVER, HIGH DISPERSION OF THE COPPER COMPONENT CAN IMPART GOOD ATTRITION RESISTANCE EVEN UNDER CYCLIC CONDITIONS. HALIDES FROM THE LEAD MOTOR MIX CONTRIBUTE SIGNIFICANTLY TO DEACTIVATION VIA DEPLETION OF THE ACTIVE COMPONENT FROM THE SURFACE OF THE CATALYST. /AUTHOR/