Nitrate storage behavior of Ba/MnOx–CeO2 catalyst and its activity for soot oxidation with heat transfer limitations

MnO –CeO2–Al2O3 mixed oxides for soot oxidation: Activity and thermal stability

“…MnCe shows five distinct peaks at ca. 210, 280, 365, 415 and 510 • C, which corroborate the previous reports [26,27]. The assignment of these peaks to different MnO x species or to specific reduction steps is not straightforward because they are not only related to the oxidation state but also to the crystallinity of manganese oxides [12,28,29].…”

“…As shown in Fig. 5, two NO 2 desorption peaks are observed at 155 and 290 • C on MnCe ascribed to the desorption of weakly adsorbed NO 2 and the decomposition of bidentate/monodentate nitrates, respectively [27]. The second peak becomes much stronger on MnCeAl, which demonstrates the importance of the high-surface-area support on the formation of nitrates coordinated to Mn x+ and Ce x+ sites.…”

“…In our previous study [27], the soot oxidation activity of Ba/MnO x -CeO 2 catalysts under a heat transfer limitation can be linearly associated to the amount of NO x releasable within 350-400 • C. Considering that no barium species is used as a NO x storage component and the catalyst-soot mixture was diluted with silica pellets to prevent reaction runaway in this study, the importance of the nitrates stored on the catalyst is weakened to a large degree. If we compare the amounts of the NO-derived NO 2 (Fig.…”

“…Thus, it confirms that both NO 2 and O 2 participate in the first half stage of soot oxidation, and the contribution of O 2 becomes predominant for MnCe-A with which the produced NO 2 is almost completely consumed by reaction with soot. We have described the "trigger" effect of NO 2 on soot oxidation in our previous studies [11,27], which also applies here. As shown in Fig.…”

Synergistic catalysis effect of Mn-promoted BaAl2O4 catalysts on catalytic performance for soot combustion

“…In Fig.4a, after exposure of BA to NO at 150°C, one strong adsorption band at 1228 cm -1 assigned to linear nitrite and two weak bands at 1535 and 1345cm -1 attributed to bidentate nitrate and bidentate nitrite (see Table 2) appeared, respectively [6,17,18]. With increasing temperature, the band at 1228cm -1 gradually decreased, while the bands at 1535 and 1345cm -1 increased, and bidentate nitrite at 1265cm -1 emerged at 300°C [6].…”