Simultaneous effect of carbon and water on NO_x adsorption on a stabilized Pt-Ba/Al2O3 catalyst

摘要

The influence of the presence of H2O on the contact between carbon, used as model soot, and a model four-way catalyst (1% Pt-10% Ba0/Al2O3) was investigated. NO_x adsorption/ TPD cycles at 300 °C together with XRD, XPS and DRIFTS characterizations showed that only surface nitrate species are destabilized by the carbon present in the catalytic bed, leading to a decrease of the NO_x storage capacity and carbonate species formation. In another way, injection of water in the reactive gas flow decreases also the NO_x storage capacity of the catalyst, but promotes the formation of stable nitrate species. A non-cumulative effect of carbon and water was observed. It was proposed that a competition between the destabilization, by carbon, of weakly bonded surface nitrate species and the enhancement of bulk nitrate species formation in the presence of water occurs.