Three-dimensionally ordered macroporous PrOx: an improved alternative to ceria catalysts for soot combustion

Abstract

The synthesis and use for soot combustion of praseodymium oxide with three-dimensionally ordered macroporous (3DOM) structure is described. This novel PrOx-3DOM catalyst is presented as an improved noble-metal-free alternative to CeO2 as soot combustion catalyst. The PrOx-3DOM catalyst presents a defined 3DOM structure with high macropores volume, which significantly enhances the solid-solid soot-catalyst contact. This enhanced contact, together with the improved reducibility of PrOx regarding CeO2, ameliorate the active oxygen production and its transfer to soot particles, improving the soot combustion with O2. In addition, the higher ability of PrOx to oxidize NO to NO2, improves the soot combustion in a higher extent than CeO2 in presence of NOx. The catalytic activity of PrOx-3DOM after several soot combustion cycles is also confirmed.