CuO nanoparticles supported by ceria for NOx-assisted soot oxidation: insight into catalytic activity and sintering

The current work introduces Cu nanoparticles (Cu-NPs) stabilized by organosilane and deposited as CuO-NPs onto ceria with two different morphologies: spongy, microstructured ceria synthesized by Solution Combustion (CeO2-SCS) and nanostructured ceria nanocubes (CeO2-NC). Catalytic activity tests have demonstrated that combination of CuO-NPs and CeO2-SCS bring significance to CO and NO oxidations as it results in easier reducibility and better metal dispersion on the surface. However, CuO-NPs with CeO2-NC give the opposite effect on CO and NO oxidations: the increase of Cu loading lowers the catalytic activity. However, Cu/CeO2-NC combination, especially the one with low Cu loading, gives the best synergy for normal soot oxidation with oxygen, thanks to the structure-sensitivity of the reaction. In the presence of NOR, Cu/CeO2-SCS catalysts are active for soot oxidation at low temperature as the catalysts favor early NO2 formation. Lastly, a series of repeated tests with NOR-assisted soot oxidation was carried out to confirm that CuO-NPs suffer easily from particle sintering, possibly via migration and coalescence. (C) 2017 Elsevier B.V. All rights reserved.