On the influence of the alumina precursor in Fe-K/Al2O3 structured catalysts for the simultaneous removal of soot and NOx: From surface properties to reaction mechanism

Cordierite-monolith supported Fe-K/Al2O3 catalysts were prepared using different alumina precursors. The catalysts were physico-chemically characterized, and their activity in the simultaneous removal of soot (carbon black) and NOx was assayed with the aim of studying the influence of the particular features of each alumina precursor on the final properties of the different prepared catalyst. Structural and textural characteristics of the catalytic layer were found to be strongly dependent on the type of alumina used, which, in turn, determined the mobility of the alkali compound. This fact together with the weaker interaction of the catalytic phase with the alumina resulted in easier K diffusion and loss in some cases, whereas, on the other hand, a stronger interaction and favorable textural features of the layer resulted in notably enhanced catalytic activity.