Active oxygen by Ce–Pr mixed oxide nanoparticles outperform diesel soot combustion Pt catalysts

Abstract

Abstract:12 13 A Ce0.5Pr0.5O2 mixed oxide has been prepared with the highest surface area and smallest 14 particle size ever reported (125 m 2 /g and 7 nm respectively), also being the most active

Catalytic regeneration of Diesel Particulate Filters: Comparison of Pt and CePr active phases

“…These results obtained with DPF-supported catalysts are consistent with those previously obtained with powder catalysts and soot:catalyst mixtures prepared in loose contact [28], where Ce 0.5 Pr 0.5 O 2 nanoparticles prepared by a microemulsion method showed even better activity than a commercial 1%Pt/alumina catalyst.…”

“…Pt-catalyzed soot combustion occurs following the NO 2 -assisted mechanism, that is, Pt oxidizes NO to NO 2 and NO 2 , which is much more oxidizing than NO and O 2 , initiates the combustion [32]. The CePr active phase also promotes this NO 2 -assisted mechanism, but is less active than Pt for NO oxidation to NO 2 [28]. Additionally, ceria-catalysts oxidize soot by the so-called active oxygen mechanism, which consists of the exchange of oxygen atoms between the ceria catalysts and the O-containing gases (O 2 is the most abundant one) producing active oxygen species that are highly active for soot combustion.…”

“…% of the total active phase mass. This active phase was previously optimized and was able to outperform the behavior of a commercial Pt catalyst in laboratory experiments performed with powder catalysts tested in loose contact under a NOx + O 2 + N 2 flow [28]. A reversed microemulsion method was used to prepare Ce 0.5 Pr 0.5 O 2 -nanoparticles precursor micelles, which was previously reported [28].…”

“…Straightforward methods like calcination of a metal precursors mixture or coprecipitation in alkali media have been studied, and also others more sophisticated synthesis pathways like surfactant-assisted methods, flame-spray synthesis, solid combustion synthesis with urea, sonochemical methods, carbon templating and citrate complexation synthesis among others [22][23][24][25][26][27]. It has been recently reported that ceriapraseodymia nanoparticles prepared by reversed microemulsion are able to outperform the soot combustion capacity of Pt in experiments performed with powder catalysts at laboratory scale [28].…”

Design structure for CePr mixed oxide catalysts in soot combustion

“…In addition, the Ce 4+ ionic radius (0.097 nm) is considerably similar to that of Pr 4+ (0.096 nm), and all of the atoms can exist with the mixed oxidation states of 3+ and 4+ in CePr solid solution. CePr mixed oxides show better performance than other CeO 2 -based catalysts in soot combustion 14,30,[32][33][34][35][36] with more active oxygen species and higher oxideion mobility, low-temperature activity, and thermal stability. 37,38 However, to the best of our knowledge, few reports exist on how Pr penetrates into the CeO 2 lattice and on the position distribution in the structure of the two metal elements, which are signicantly important for the identication of the relationship between the structures and catalytic properties of CePr mixed oxides.…”