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

Abstract

Environmental contamination such as soot particles and NO x have aroused extensive attraction recently. However, the main challenge lies in the oxidation of soot at mild temperature with the assistance of NO x . Here, a series of core–shell MnCeO x catalysts were successfully synthesized by hydrothermal method and employed for low-temperature catalytic oxidation of soot in the presence of NO x . X-ray diffraction (XRD), inductively coupled plasma - optical emission spectrometry (ICP-OES), energy-dispersive X-ray spectroscopy (EDS), transmission electron microscopy (TEM), N 2 adsorption/desorption, H 2 -temperature programmed reduction (H 2 -TPR), O 2 -temperature programmed desorption (O 2 -TPD), X-ray photoelectron spectroscopy (XPS) and Raman 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 T 50 about 350 °C for soot oxidation. Besides, soot particle is oxided at 304 °C in presence of NO, while T 50 augments up to 340 °C in the absence of NO. In the NO x -assisted elimination cases of soot, NO 2 generated 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 MnCeO x catalysts is also proposed in this paper. Core-shell MnCeO x catalysts with different Mn contents were successfully synthesized through hydrothermal method and they exhibit superior catalytic ability for soot oxidation. This work achieves NO x -assisted soot combustion at mild temperature and can be used as alternative option in catalytic processes of soot particles. • A series of MnCeO x catalysts were successfully synthesized by hydrothermal method and the core-shell structure is confirmed. • MnCeO x catalysts showed superior catalytic capability for low-temperature catalytic oxidation of soot in the presence of NO x and the lowest catalytic temperature was achieved at 304 °C. • Possible catalytic mechanism over core-shell MnCeO x catalysts was also proposed.