FTIR and Transient Reactivity Experiments of the Reduction by H2, CO and HCs of NOx Stored Over Pt–Ba/Al2O3 LNTs

The reduction of NOx stored over a Pt–Ba/Al2O3 Lean NOx Trap is analysed when H2, CO or heptane are used as reductants. In all cases, the reduction proceeds via a Pt-catalyzed process involving the formation of intermediate species like ammonia and isocyanates in the case of H2 and CO, respectively. No specific intermediates have been observed when heptane is used as reductant. It is claimed that the role of the reductant is to keep Pt in a reduced state; this favours nitrate decomposition and reduction over the Pt sites. The effect of water on the reaction is also investigated.