Catalytic Coatings for Improving the Environmental Safety of Internal Combustion Engines

AK9 silumin samples (Al-Si) were treated by plasma electrolytic oxidation (PEO) in order to obtain surface oxide layer. These samples were not enough active as catalysts in CO oxidation (1% CO vol in air). Palladium activated samples were more active. Thus the temperature of 50% CO conversion for Pd/SiO₂/Al-Si sample is T₅₀ = 152 °C and T₉₉ is 170 °C. According to IR spectroscopy and Raman spectroscopy as well as scanning electron microscopy data, the active layer of the most active sample Pd/SiO₂/Al-Si, present as noncrystalline SiO₂ with γ-alumina and palladium inclusions, the covering has a depth of 10-20 nm. According to atomic force microscopy data the surface layer is roughly ~ 10 – 20 nm.