Oxidation and Surface Segregation Behavior of a Pt–Pd–Rh Alloy Catalyst
Abstract
Platinum gauze catalysts are used extensively in the production of nitricacid from ammonia, where they are subject to harsh operating conditions combiningelevated temperatures and oxidizing environments. These cause significant loss of metalspecies as volatile oxides. How different metallic species behave in these environments ata fundamental, atomic-scale level is not well understood. In this work, we study the earlystages of oxidation of a Pt−Rh−Pd gauze at temperatures of 873−1273 K. Using acombination of advanced experimental methods, we explore how the oxidation behaviorcan strongly influence the surface and near-surface gauze microstructure. We show thatRh and Pd can segregate on different areas of the same surface and discuss how suchatomic migration can be linked to mechanisms of metal loss from such alloys.