Total oxidation catalysts based on manganese or copper oxides and platinum or palladium II: Activity, hydrothermal stability and sulphur resistance

Abstract

Deactivation of catalysts based on either manganese oxides, copper oxides, platinum, palladium or combinations of these metal oxides and noble metals supported on γ-alumina was studied. The activity of the catalysts for the oxidation of carbon monoxide, naphthalene and methane, in a mixture resembling the flue gases from wood combustion, was measured before and after exposure of the catalysts either to a temperature of 900°C in the presence of steam or to sulphur dioxide. Most of the mixed catalysts were more resistant to hydrothermal and sulphur treatments than the catalysts with a single active component. After the hydrothermal treatment the activity of the MnO x catalyst was enhanced. When Pt is combined with MnO x or CuO x , the loss of activity of Pt was decreased during the hydrothermal treatment. Also, the hydrotreated mixed MnO x –Pd and CuO x –Pd catalysts were more active than the treated Pd catalyst for the oxidation of methane. After sulphur treatment, the activities of the mixed MnO x –Pt (Pt: 0.05 mol%), MnO x –Pd and CuO x –Pd catalysts were improved for the oxidation of carbon monoxide and naphthalene. Among the catalysts studied, the MnO x –Pt, CuO x –Pt and CuO x –Pd catalysts, with a metal oxide and a noble metal loading of 10 and 0.1 mol%/γ-alumina, respectively, had the best combination of activity, thermal stability and resistance to sulphur treatment.