Core-shell MnCeOxcatalysts for NO oxidation and mild temperature diesel soot combustion

Environmental contamination such as soot particles and NOxhas aroused extensive attraction recently. However, the main challenge lies in the oxidation of soot at mild temperature with the assistance of NOx. Here, a series of core–shell MnCeOxcatalysts were successfully synthesized by hydrothermal method and employed for low-temperature catalytic oxidation of soot in the presence of NOx. X-ray diffraction (XRD), inductively coupled plasma-optical emission spectrometry (ICP-OES), energy-dispersive X-ray spectroscopy (EDS), transmission electron microscopy (TEM), N2adsorption/desorption, H2-temperature programmed reduction (H2-TPR), O2-temperature programmed desorption (O2-TPD), X-ray photoelectron spectroscopy (XPS) and Raman analyses were conducted for identifying the structure of prepared catalysts and investigating redox properties of the core–shell mixed oxide, which shows excellent performance for NO oxidation and the T50about 350 °C for soot oxidation. Besides, soot particle is oxided at 304 °C in the presence of NO, while T50augments up to 340 °C in the absence of NO. In the NOx-assisted elimination cases of soot, NO2generated from NO in emission gas is generally reckoned as a facilitator which significantly reduces ignition temperature of soot particles. Possible catalytic mechanism over core–shell MnCeOxcatalysts is also proposed in this paper.