Selective CO oxidation reaction (SELOX) over cerium-doped LaCoO3 perovskite catalysts

Perovskite-type oxides La1−xCexCoO3 (x = 0, 0.05 and 0.10) were prepared, characterized and evaluated in the selective CO oxidation reaction (SELOX). The citrate synthesis methodology favored the formation of perovskites with rhombohedral structure and low specific surface area (<14 m2 g−1). TPR profiles showed intermediates during the reduction process but the addition of cerium not only inhibited its formation but also promoted structural modifications in the perovskite lattice. XRD diffractograms showed the formation of perovskite without phase segregation. Temperature programmed reactions showed selective CO oxidation at low temperature besides undesired reactions at higher temperatures. Catalytic tests of the SELOX reaction showed 100% of CO conversion at 200 °C. Higher temperatures favored hydrogen oxidation and methanation. Catalysts LaCoO3 and La0.95Ce0.05CoO3 presented good stability during 48 h of reaction. The LaCoO3 catalyst was sensitive to the presence of H2O and CO2 in the feed stream, however its CO conversion was easily restored after removing these compounds from the feed stream.

Figure optionsDownload high-quality image (69 K)Download as PowerPoint slideResearch highlights▶ Citrate method is suitable for preparation of perovskite-type oxides La1−xCexCoO3. ▶ Results suggest insertion of Ce in the lattice for x = 0.05, 0.10 on La1−xCexCoO3. ▶ TPSR results show CO oxidation at low temperature and above undesired reactions. ▶ All catalysts are active for the selective oxidation reaction below 220 °C. ▶ Catalyst is very sensitive for contaminants in the feed stream but easily restored.