EFFECT OF THERMAL AGING IN OXIDIZING OR REDUCING ATMOSPHERE ON THE TEXTURE AND STRUCTURE OF PALLADIUM, COPPER AND PALLADIUM-COPPER ON ALUMINA CATALYSTS

A series of palladium, copper and palladium-copper supported on alumin a catalysts were aged at high temperature (100 degrees C) in oxidizing (oxygen) or reducing (hydrogen) atmosphere. The effect of this treatm ent on the texture and structure of these samples was studied. Oxidizi ng atmosphere gives large particles of palladium oxide, whgereas reduc ing atmosphere gives large particles of copper or of palladium-copper alloys. Palladium is not detected with pure palladium on alumina catal ysts when agend in reducing conditions while the hydrogenating activit y is drastically decreased.