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Abstract: A series of Li-based lean-burn NO x trap (LNT) catalysts Pt/Li/TiO2–MO x (M=Al, Zr, Si, Sn) were prepared by sequential impregnation with the supports TiO2–MO x synthesized by co-precipitation. The support effect on the NO x storage and sulfur-resisting performance of Pt/Li/TiO2–MO x catalysts was investigated carefully. The NO x storage capacity of fresh Pt/Li/TiO2 is greatly improved by doping with Al2O3 or ZrO2 due to the remarkably increased specific surface area and the oxidation ability of the catalysts. HR-TEM and H2-chemisorption results reveal that the oxidation ability of Pt/Li/TiO2–MO x is mainly determined by Pt crystallite size. Larger Pt crystallites correspond to stronger oxidation ability. The regeneration of sulfated Pt/Li/TiO2–MO x strongly depends on the total acidity of the supports, including Brønsted and Lewis acid; the supports with larger acidity possess higher ability of sulfur-resistance and regeneration. The results of in situ DRIFTS show that over Pt/Li/TiO2–MO x (M=Al, Zr, Si, Sn) NO x is mainly stored as ionic nitrate species at 350°C. Taking the NSC and regeneration ability into account, the catalyst Pt/Li/TiO2–Al2O3 is the most promising one for practical application. [Copyright &y& Elsevier]

Abstract: The BaFeO3−x perovskite catalyst was prepared by sol–gel method for NO x storage under lean-burn conditions. During the catalyst precursor calcination, a series of complex solid reactions happened, and the BaCO3, formed during citric acid combustion, played a key role to react with the spinel species achieving the aimed perovskite. On the Ba–Fe–750F catalyst, the perovskite phase and the small amount of spinel phase were evidenced by XRD, and some well dispersed carbonate was also detected by FT-IR. Under lean-burn conditions, the NO x was easily stored on the Ba–Fe–750F catalyst, and its optimized NO x storage capacity (NSC), i.e. 333.5μmolg−1, was obtained at 400°C. At above 400°C, the stored nitrate became unstable and decomposed, resulting in the sharp decrease of NSC. Two kinds of the NO x storage sites were identified by in situ DRIFTS experiments that the carbonate remaining on the catalyst could transform to monodentate nitrate, and the A site Ba in the perovskite structure could directly bind with NO x to form N-bounded nitrate. This BaFeO3−x perovskite catalyst was a potential NO x storage material with noble metal free. [ABSTRACT FROM AUTHOR]