Influence of the storage material on the storage of NOx at low temperatures

Artikel i vetenskaplig tidskrift, 2004

The NOx storage performance at low temperature (100–-200°C) has been studied for model NOx storage catalysts. The catalysts were prepared by sequentially depositing support, metal oxide and platinum on ceramic monoliths. The support material consisted of acidic aluminium silicate, alumina or basic aluminium magnesium oxide, and the added metal oxide was either ceria or barium oxide. The NOx conversion was evaluated under net-oxidising conditions with transients between lean and rich gas composition and the NOx storage performance was studied by isothermal adsorption of NO2 followed by temperature programmed desorption of adsorbed species. The maximum in NOx storage capacity was observed at 100°C for all samples studied. The Pt/BaO/Al2O3 catalyst stored about twice the amount of NO x compared with the Pt/Al2O3 and Pt/CeO2/Al2O3 samples. The storage capacity increased with increasing basicity of the support material, i.e. Pt/Al2O3·SiO2 < Pt/Al2O3 < Pt/Al2O3 · MgO. Water did not significantly affect the NO x storage performance for Pt/Al2O3 or Pt/BaO/Al2O3.