Acta Phys. -Chim. Sin. ›› 2015, Vol. 31 ›› Issue (6): 1153-1161.doi: 10.3866/PKU.WHXB201504145

• CATALYSIS AND SURFACE SCIENCE • Previous Articles     Next Articles

Effects of Rare-Earth Additives on Structures and Performances of CuO-CeO2-SiO2 Catalysts for Recycling Cl2 from HCl Oxidation

XIE Xing-Xing1,2, FEI Zhao-Yang1,2, ZOU Chong1,2, LI Zheng-Zhou1,2, CHEN Xian2, TANG Ji-Hai2, CUI Mi-Fen2, QIAO Xu1,2   

  1. 1 State Key Laboratory of Materials-Oriented Chemical Engineering, Nanjing Tech University, Nanjing 210009, P. R. China;
    2 College of Chemistry and Chemical Engineering, Nanjing Tech University, Nanjing 210009, P. R. China
  • Received:2014-12-23 Revised:2015-04-14 Published:2015-06-05
  • Contact: FEI Zhao-Yang, QIAO Xu E-mail:zhaoyangfei@njtech.edu.cn;qct@njtech.edu.cn
  • Supported by:

    The project was supported by the National Key Technology Research and Development Program of the Ministry of Science and Technology of China (2011BAE18B01), Research and Development Program of Jiangsu Province, China (BE2011830), Higher Education Natural Science Foundation of Jiangsu Province, China (13KJB530006), National Natural Science Foundation of China (21306089) and China Postdoctoral Science Foundation (2013M531340).

Abstract:

CuO-CeO2-SiO2 and rare-earth-doped CuO-Ce0.9M0.1O2-SiO2 (M=La, Pr, Nd) catalysts for recycling Cl2 from HCl oxidation were prepared by a template method, using activated carbon as a hard template. The catalyst structures were determined using X-ray diffraction (XRD), N2 adsorption-desorption, transmission electron microscopy (TEM), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and H2 temperatureprogrammed reduction (H2-TPR). The catalytic performances were also investigated. The results showed that La, Pr, and Nd cations were incorporated into the CeO2 lattice and formed nanosized solid solutions; this greatly reduced the catalyst grain sizes, leading to higher surface areas. In addition, the oxygen vacancy concentrations were significantly improved. The changes in the structures and surface properties of the solid solutions significantly affected the HCl catalytic oxidation performances. The order of the activities of various catalysts was CuO-Ce0.9La0.1O2-SiO2>CuO-Ce0.9Nd0.1O2-SiO2>CuO-Ce0.9Pr0.1O2-SiO2>CuO-CeO2-SiO2. The oxygen vacancy concentrations of the solid solutions were strongly related to their catalytic activities. However, the structures and performances of the Ce0.9M0.1O2-SiO2 catalysts showed that an increase in the number of oxygen vacancies resulted in decreased catalytic activities of the solid solutions. Kinetic studies showed that oxygen adsorption could be the rate-determining step for rare-earth-doped catalysts; a higher oxygen vacancy concentration in the solid solution led to a slower reaction rate when the volumetric flow ratio of O2 to HCl was 1. For the CuOCe0.9M0.1O2-SiO2 catalysts, spillover of oxygen species in the solid solution into the highly dispersed CuO interfaces was enhanced, which increased the overall reaction rate and gave high activity.

Key words: Rare earth, CuO-CeO2, HCl, Catalytic oxidation, Chlorine, Oxygen vacancy

MSC2000: 

  • O643