A Co3O4-CeO2 functionalized SBA-15 monolith with a three-dimensional framework improves NOx-assisted soot combustion

In this work, a cobalt and cerium composite oxide functionalized SBA-15 monolith (SM) with an inner three-dimensional (3D) network structure (CoCe/SM) was prepared by isovolumetric impregnation. Its catalytic activities towards NOx-assisted soot combustion were evaluated and the loading and Co/Ce ratio were optimized. X-ray diffraction, scanning electron microscopy, energy dispersed spectroscopy, transmission electron microscopy, N-2 adsorption, X-ray photoelectron spectroscopy, H-2 temperature-programmed reduction and O-2 temperature-programmed desorption were employed to characterize the samples. It was revealed that, compared with unsupported Co3O4-CeO2 particles, the CoCe/SM catalysts with optimized Co3O4-CeO2 loading showed much higher catalytic ability, achieving a complete oxidation of the soot to CO2 below 400 degrees C in the presence of NOx, which is attributed to the high dispersion of Co3O4-CeO2 on SM and the cross-linked macroporous structure of SM that can house the soot particulates, thus providing closer contact between the soot and catalytically active sites.