The influence of cerium to urea preparation ratio of nanocrystalline ceria catalysts for the total oxidation of naphthalene

The influence of cerium salt/urea ratio on the activity of nanocrystalline ceria catalysts prepared by homogeneous precipitation with urea for the complete oxidation of naphthalene has been evaluated. Ceria catalysts were prepared from five different cerium salt/urea ratios (2:1, 1:1, 1:2, 1:3 and 1:4). Catalyst characterization (by BET, XRD and TPR) only revealed subtle differences in the characteristics of these catalysts with cerium salt to urea ratio. However, Raman and scanning electron microscopy (SEM) results indicated differences in the oxygen defect concentration (FWHM of Raman band) and morphology of the catalysts with variation of the preparation ratio. Catalysts prepared with 2:1, 1:1 and 1:4 were significantly more active than those prepared from 1:2 and 1:3 ratios. A relationship between the concentration of oxygen defects and naphthalene oxidation activity has been established. The activity of the catalysts is thought to be related to a combination of oxygen defect concentration, surface reducibility and morphology.