Role of nitrogen dioxide in the oxidation of diesel soot on promoted mixed catalysts with fluorite and perovskite structures

Nanocomposite structure and reactivity of perovskites based on lanthanum manganites

“…For different perovskite catalysts, the structural sensi tivity is less expressed, and small differences in activity are observed only at the initial stage of oxidation. Due to the larger content of the weakly bound nitratenitrite surface complexes, which have a high oxidation ability [122], the temperature of the initiated oxida tion of soot is lower the higher the content of weakly bound oxygen in the perovskite (Fig. 8).…”

“…In the oxidation of soot-a solid oxidized material composed of polyaromatic compounds-at a high level of total activity the subse quent stages of destruction/transformation reduce the specificity of the catalytic action and the differences in the composition of the perovskite surface. At the same time, a high content of weakly bound oxygen on such materials, as compared to Ce-Zr-O fluorites con taining easily reduced transition metal cations [55]) gives them a higher activity in the initiated oxidation reaction occurring with the participation of only cata lyst oxygen [25,26,122]. The differences in tempera ture of the start of such an initiation are 75-150°С.…”

“…12b) [25,26,122]. In the oxidation of soot-a solid oxidized material composed of polyaromatic compounds-at a high level of total activity the subse quent stages of destruction/transformation reduce the specificity of the catalytic action and the differences in the composition of the perovskite surface.…”

“…Weakly bound oxygen with Е d ~ 40 kJ/mol (the α form) can desorb from Mn 3+ /Mn 4+ (Fe 4+ , Bi 5+ ) surface defect centers local ized in the vicinity of nanocomposite domain bound aries. A part of desorbed molecular oxygen formed from the low charged oxygen species (О -) is in a sin glet state [122]. In the oxygen isotope heteroexchange experiments the presence of weakly bound low charged forms of surface oxygen results in formation of asymmetric 18 О 16 О molecules (the second type of exchange) [111].…”

Preparation and catalytic activity of K4Zr5O12 for the oxidation of soot from vehicle engine emissions

“…However, the soot particulate matter (PM) emitted from diesel engine is a serious contamination for human beings, as it can penetrate into the lung and cause severe bronchial troubles [5][6]. With the regulations for pollutant emissions becoming stricter, it becomes very important and urgent to develop the after-treatment technologies for PM abatement [7][8][9][10]. Among the technologies, diesel particulate filter (DPF) is considered as the most promising and effective mean to collect over 90% of diesel soot.…”