Changes in Pt-Rh catalysts in the working environment

Abstract

The surface reconstruction on rhodium-platinum catalyst gauzes has been examined using the scanning electron microscope techniques. The nucleation and growth of large cage-like features, developed on the gauze surfaces during operation in the ammonia oxidation process, were studied in detail. It is concluded that a vapor phase mechanism involving transport of platinum oxide is responsible for the observed reaction, and the reason why this process operates only over a limited range of temperature and pressure is explained. Some comments are also made on the related reconstruction observed on gauzes, used during the production of hydrogen cyanide by the Andrussow process.