Abstract

Simultaneous poisoning of sulfur + phosphorus on a platinum-based diesel oxidation catalyst was studied to gain a deeper understanding on the <u>catalyst deactivation</u>. Compared to a single poisoning (sulfur or phosphorus), the simultaneous poisoning had a severe effect on the catalyst activation: light-off temperature for 90% conversion of propene was not reached, this of <u>carbon monoxide</u> was much higher than expected, and the maximum conversion of nitrogen monoxide collapsed. With very comprehensive structural characterization by various methods (e.g. STEM-EDS, XPS, DRIFTS) used, we achieved to conclude an explanation for this. In the case of the S + P-poisoning of the catalyst, formed aluminum phosphate was found to block adsorption sites for sulfur species on alumina and sulfur adsorbs mainly on <u>cerium</u> oxides. In addition, sulfur species remain with and in the vicinity of the platinum particles blocking active sites.