Silver-based storage catalyst for neutralization of nitrogen oxides

A silver-based storage catalyst was synthesized and characterized in searching of alternative to the conventional Pt/BaCO3/Al2O3 catalyst for neutralization of nitrogen oxides in automotive exhaust gases. It was established that the Ag/BaCO3/Al2O3 catalyst reaches its highest activity at a temperature of 500 °C, showing lower activity when compared with the platinum catalyst. It was found that the mechanism on NOx accumulation on Ag/BaCO3/Al2O3 catalyst involves formation of nitrite (NO2-), followed by oxidation to nitrate (NO3-) species and decomposition of nitrates in reducing conditions. The silver-based storage catalyst demonstrated a higher resistance towards poisoning with SO2 than the platinum-based catalyst. After reduction test in the presence of SO2, both a crystalline BaSO4 phase and sulfate groups bound to alumina were found. The results obtained were considered as a promising approach for development of new and less expensive Ag-based NSR catalyst.