Abstract
Morphological and chemical changes of the Pt-Rh catalyst and palladium-based catchment gauzes used in medium- and low-pressure ammonia oxidation plants have been studied by scanning electron microscopy, combined with energy dispersive X-ray analysis (SEM-EDX), and X-ray photoelectron spectroscopy (XPS). It has been observed that the noble metals are mostly in the metallic state, and catalyst deactivation is determined by rhodium enrichment in the alloy surface. In the cases of a strong “faceting” of the wires, which tends to homogenize the catalyst surface, a good agreement between the surface composition determined by EDX and XPS was found. The Pt/Pd and Rh/Pd ratios in the catchment gauzes decreased markedly from the top to the bottom gauzes of the pack, indicating the directional effect of metal condensation or deposition from the gas stream.
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Fierro, J.L.G., Palacios, J.M. & Tomas, F. Characterization of catalyst and catchment gauzes used in medium- and low-pressure ammonia oxidation plants. J Mater Sci 27, 685–691 (1992). https://doi.org/10.1007/BF00554037
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DOI: https://doi.org/10.1007/BF00554037