On the activity and stability of Pt-K/Al2O3 LNT catalysts for diesel soot and NOx abatement

• The soot decreases the NOx storage activity of Pt-K/Al2O3 catalyst at any temperature in the range 250–350 °C.
• The stability of the species stored over Pt-K/Al2O3 catalyst is lower in the presence of soot.
• Nitrates ad-species directly interact with soot and participate to the soot combustion.
• Aged catalyst shows a lower storage capacity and a lower soot oxidation activity attributed to the volatile nature of K-active species.

DPNR Pt-K/Al2O3 catalyst has been studied for the simultaneous removal of soot and NOx, in the presence of both water and carbon dioxide. In particular, the effect of soot on the NOx storage activity and on the stability of Pt-K/Al2O3 catalyst has been addressed. It has been found that: (i) the presence of soot decreases the NOx storage activity at any temperature in the range 250–350 °C; (ii) the stability of the adsorbed species is lower in the presence of soot; (iii) nitrates ad-species directly interact with soot and participate to the soot combustion; (iv) aged catalyst shows a lower storage capacity and a lower soot oxidation activity attributed to loss of K-active species.

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