The Mechanism of Reconstruction of Rhodium-Platinum Catalyst Gauzes: An Explanation of the New Surface Morphology

Abstract

The surface reconstruction on rhodium-platinum catalyst gauzes has been examined using scanning electron microscope techniques. The nucleation and growth of the large cage-like features which develop on the gauze surfaces during operation in the ammonia oxidation process have been studied in detail. It is concluded that a vapour 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.