PREPARATION OF ALUMINA-SUPPORTED PALLADIUM-PLATINUM CATALYSTS BY SURFACE REDOX REACTIONS - ACTIVITY FOR COMPLETE HYDROCARBON OXIDATION

The complete oxidation of hydrocarbons (methane, propane and propene) and the O-18/O-16 isotopic exchange were investigated on supported pal ladium-platinum catalysts. The bimetallic catalysts were prepared by c ontrolled surface reactions (the ''refilling'' RC and the ''direct red ox reaction'' RD) and by coimpregnation CI. The preparation methods le ad to different kinds of platinum deposit, which involve different beh aviours in hydrocarbon oxidation and in isotopic exchange. Even if the structure of bimetallic catalysts is modified under oxygen, the resul ts show that the bimetallic catalysts keep a memory effect of their pr eparation method under the reaction conditions used in this work. (C) 1998 Elsevier Science B.V. All rights reserved.