Effect of Pd addition on the efficiency of a NOx-trap catalyst: A FTIR operando study

The effect of Pd addition over an industrial catalyst Pt/Ba/CeO2/Al2O3 in the lean-NOx trap process was investigated. FTIR operando was carried out for an in depth understanding of the chemical mechanisms taking place onto the catalyst in working conditions close to the real ones. The presence of Pd provokes a synergetic effect, probably related to a Pt–Pd alloy that improves the NO oxidation and therefore the NOx trapping capacity. Besides, Pd also favours the hydrocarbon oxidation and thus increases the efficiency of the process. On the basis of the present investigations and previous works from the literature, a reaction mechanism is proposed.