“…and nonmetal ingredients (e.g., Cl and S). Impurities of Mg, Al, S, Cl, Ca, Mn, Fe, Ni, Cu, Ba, and Au and are all reported [1,2] to decrease the activity of Pt-Rh catalysts. However, some impurities can be oxidized under ammonia oxidation conditions to solid oxides that are stable at these high temperatures and are themselves catalytically active.…”