Heterogeneous Catalytic Oxidation of Ammonia by Various Transition Metals

• Petrus C. M. Laan ^[1] ; Mareena C. Franke ^[1] ; Richard van Lent ^[1] ; Ludo B. F. Juurlink ^[1]
  1. [1] Leiden University

     Leiden University

     Países Bajos

     
• Localización: Journal of chemical education, ISSN 0021-9584, Vol. 96, Nº 10, 2019, págs. 2266-2270
• Idioma: inglés
• Texto completo no disponible (Saber más ...)
• Resumen

  • A well-known demonstration is adapted to simplify the illustration of heterogeneous catalytic oxidation of ammonia. Various metal catalyst wires are placed above the liquid level in a flask containing concentrated ammonia. After brief preheating, some metal wires continue to glow, providing visual evidence of an overall exothermic reaction taking place at the catalyst surface. Thermal heating by a butane flame prior to insertion and in situ resistive heating using a power supply yield identical results. Active catalysts are the group 9 and 10 elements Rh, Ir, Pd, and Pt. Besides the illustration of the Sabatier principle, the effect of the ammonia-to-oxygen ratio can also be visualized, and active metals vary in the production of a grayish smoke. These observations provide a starting point to discuss catalytic selectivity, a topic of great relevance to industrial catalytic oxidation of ammonia.