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

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 novel metal-free alternative to CeO2 as soot combustion catalyst. The PrOx-3DOM catalyst presents a well-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.The authors thank the financial support of the Spanish Ministry of Economy and Competitiveness (Project CTQ2015-67597-C2-2-R and grant FJCI-2015-23769), the Spanish Ministry of Education, Culture and Sports (grant FPU14/01178) and the UE (FEDER funding)