Lean NOXX–SnO2–CeO2 catalyst at low temperatures

• The Mn–Sn–Ce–O catalysts showed excellent NOX storage capacities at 100 °C.
• Defect oxygen was vital to oxidize NO during NOX storage, and incorporating Ce improved NO oxidation ability.
• The synergetic effect between Sn and Ce increased the amount of NO2 adsorption sites on the surface.
• The formation of the intermediate product NO−-Ce3+ prompted the NO adsorption on Mn–Sn–Ce–O catalysts.

Mnx–Sny–Ce1−x−y–O2±μ (denoted Mn–Sn–Ce–O) catalysts prepared through co-precipitation were used for NOX storage under lean conditions at a low temperature (100 °C). The NOX storage capacity (NSC) of the Mn–Sn–O dramatically increased after incorporating Ce. The catalyst, which has a 4:5:1 molar ratio of Mn:Sn:Ce (denoted Mn0.4Sn0.5Ce0.1), exhibited a breakthrough time of 16 min and a NSC of 565.9 μmol g−1 at a gas hourly space velocity (GHSV) of 48,000 mL h−1 g−1. Combining the NO adsorption/desorption results with XPS and H2-TPR, results revealed that the NO oxidation ability of Mn–Sn–Ce–O had improved dramatically due to the Sn–Ce interactions and the surface defect oxygen species. Furthermore, the NO-TPD, NO2-TPD and in situ DRIFTS data indicated that incorporate Ce into the Mn–Sn–O induced a synergistic Sn–Ce effect during NOX storage, thereby producing more NO2 adsorption sites on the surface.

A novel Mn–Sn–Ce–O metal oxide catalyst showed excellent NOX trap performance at 100 °C. Compared with binary metal oxides, Mn–Sn–Ce–O catalysts performed better NO oxidation and NO2 adsorption ability because of the Ce incorporation.Figure optionsDownload high-quality image (138 K)Download as PowerPoint slide