The effects of different supports (A12O3, TiO2, MgO and SiO2) were examined on the formation and stability of isocyanate species in the NO + CO reaction on Pd, Ru, Rh and Ir catalysts. Taking into account the results obtained earlier for supported Pt, some general conclusions were drawn. The formation of isocyanate species occurred comparatively easily on TiO2-supportedmetals, and it was always very slow on silica-supported metals. The location of the isocyanat? band hardly depended on the metal, but was strongly influenced by the supports. It appeared at 2210-2215 cm-1 On M/TiO2, 2264-2272 cm-1 on M/A12O3, 2 228 -2 241 cm-1 on M/MgO and 2310–2318 cm-1 on M/SiO2. The supports exerted marked influences on the stability of the socyanate species, too; it was relatively unstable on M/TiO2, but was extremely stable on M/SiO2 catalysts. The results were explained by assuming that isocyanate forms on the metals, but migrates rapidly onto the supports, which basically determine its behavior.
- IR spectroscopy
- Noble metals
ASJC Scopus subject areas
- Physical and Theoretical Chemistry