Soot combustion perovskite catalysts

For all these reasons, the aim of this chapter is not to conclude which are the best and worst soot combustion catalysts, but only to compile the information available in the literature about the diesel soot combustion perovskite catalysts. 

Soot Combustion Perovskite Catalysts Effect of Partial Substitution of Cations in the... 

The general formula of perovskites is ABO3, and soot combustion perovskite catalysts with many different cations have been reported for both A and B positions [7]. For instance, DoggaU et al. [8] prepared BaRuOs perovskites by coprecipitation method and its catalytic activity was tested for diesel soot oxidation with O2. The catalytic activity was attributed to the dissociative adsorption of oxygen on the catalyst surface, and was postulated that the 120 planes of BaRuOs can have abundant Ru atoms that can facilitate the O2 dissociation. The advantage of using this perovskite with regard to pure ruthenium oxide was attributed to the thermal stability of Ru within the BaRuOs matrix as well as basicity offered by Ba. 

LaCrOs, LaFeOg, and LaMnOs perovskite catalysts were compared and the highest activity for soot combustion of the chromite catalyst was related to its highest concentration of suprafacial, weakly chemisorbed oxygen, which actively contributes to soot combustion by spillover in the temperature range of 300-500 °C [29]. The introduction of lithium into the chromium position of LaCrOs soot combustion perovskite catalysts has also shown to improve the activity due to enhancement of the amount of weakly chemisorbed oxygen 0 species [30]. 

In line with this, the highest activity of Lao,6Sro,4Co03 5 among a series of Lai tSr tCo03 5 (x = 0.2, 0.3, 0.4, 0.5) soot combustion perovskite catalysts was related to the presence of the highest concentration of surfece oxygen [27]. 

Three-Dimensionally Ordered Macroporous Soot Combustion Perovskite Catalysts... 

As it is deduced from data compiled in Table 19.1, one of the properties that limit the activity of perovskite catalysts for soot combustion is their very low surface area, with BET values typically lower than 25 m /g. Well-ordered perovskite nanocrystals have not been reported and, therefore, areas are usually low. The positive consequence of the formation of large perovskite crystals is the high thermal stability usually attributed to soot combustion perovskite catalysts. 

Study of Soot Combustion Perovskite Catalysts in Real Diesel Exhausts 1445... 

Lopez-Suarez, F.E., Bueno-Ldpez, A., Illdn-Gomez, M.J., Ura, B., and Trawczynski, J. (2009) Potassium stability in soot combustion perovskite catalysts. Top. (Zatal., 52,2097-2100. 

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