Catalytic performance of Ce1-xLnxOy of nanocrystalline Ln (III-IV)-substituted ceria

Abstract

The activity of several lanthanide promoted Ceria in CO oxidation was studied. Samples were obtained by a high yield and sustainable method by urea thermal decomposition. Precursors basic carbonates, Ce1-xLnx(OH)CO3, being Ln = La (III), Sm(III), Gd(III), Pr(III) were prepared in the range of compositions 0 to 30 at.%. These precursors were annealed to moderate temperature obtain Ln-Ce mixed oxides, at 450ºC. These exhibit large surface areas up to 120 m2/g. Their catalytic performance revealed good activity towards CO oxidation  (COOX) for all samples. However, a different behavior may be observed for Ln content higher than 20 at.%. By the reactor operation in differential conditions, the activation energy for COOX were obtained for all samples. The rise of activation energy as a function of Ln(III-IV) content is analyzed in the frame of phase stability and surface segregation.