ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Promotional effect of cobalt addition on catalytic performance of Ce0.5Zr0.5O2 mixed oxide for diesel soot combustion

Yan-Hua Zhang, Hai-Long Zhang, Yi Cao, Yi Yang, Bao-Qiang Xu, Ming Zhao, Mao-Chu Gong, Hai-Di Xu, and Yao-Qiang Chen

Key Laboratory of Green Chemistry and Technology of the Ministry of Education, College of Chemistry

E-mail: nic7501@scu.edu.cn

Abstract: A series of Co-modified Ce_0.5Zr_0.5O₂ catalysts with different concentrations of Co (mass %: 0, 2, 4, 6, 8, 10) was investigated for diesel soot combustion. Ce_0.5Zr_0.5O₂ was prepared using the co-precipitation method and Co was loaded onto the oxide using the incipient wetness impregnation method. The activities of the catalysts were evaluated by thermogravimetric (TG) analysis and temperature-programmed oxidation (TPO) experiments. The results showed the soot combustion activities of the catalysts to be effectively improved by the addition of Co, 6 % Co/Ce_0.5Zr_0.5O₂ and that the 8 % Co/Ce_0.5Zr_0.5O₂ catalysts exhibited the best catalytic performance in terms of lower soot ignition temperature (T_i at 349 °C) and maximal soot oxidation rate temperature (T_m at 358 °C). The reasons for the improved activity were investigated by X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET), H2 temperature-programmed reduction (H₂-TPR), X-ray photo-electron spectroscopy (XPS) and transmission electron microscopy (TEM). These results revealed that the presence of Co could lower the reduction temperature due to the synergistic effect between Co and Ce, thereby improving the activity of the catalysts in soot combustion. The 6 % Co catalyst exhibited the best catalytic performance, which could be attributed to the greater amounts of Co³⁺ and surface oxygen species on the catalyst.

Keywords: Co3O4 – Ce0.5Zr0.5O2 – catalytic performance – diesel soot combustion

Full paper is available at www.springerlink.com.

DOI: 10.1515/chempap-2016-0070

Chemical Papers 70 (10) 1370–1379 (2016)