Effect of Support on Noble Metal Catalysts for Three-Way Conversions

Noble metals including small amounts of rhodium (Pt/Rh = 14 ∼ 19 weight ratio) supported on silica, alumina and silica-alumina were tested for three-way conversions. Catalysts were evaluated fresh, after in-situ hydrothermal aging at 816°C, and after cyclic pulsator aging at 538°C ∼ 704°C. All samples exhibited good three-way conversions when fresh. Overall, the catalysts supported on alumina performed the best based on resistance toward chemical poisons such as Pb, P and S.