Surface redox characters and synergetic catalytic properties of macroporous ceria-zirconia solid solutions

Jing Ouyang; Zai Zhao; Huaming Yang; Junkai He; Steven L Suib

doi:10.1016/j.jhazmat.2018.11.083

Surface redox characters and synergetic catalytic properties of macroporous ceria-zirconia solid solutions

J Hazard Mater. 2019 Mar 15:366:54-64. doi: 10.1016/j.jhazmat.2018.11.083. Epub 2018 Nov 22.

Authors

Jing Ouyang¹, Zai Zhao², Huaming Yang², Junkai He³, Steven L Suib⁴

Affiliations

¹ Centre for Mineral Materials, School of Minerals Processing and Bioengineering, Central South University, Changsha 410083, China; Hunan Key Lab of Mineral Materials and Application, Central South University, Changsha 410083, China; Key Lab of Clay Mineral Functional Materials in China Building Materials Industry, Changsha 410083, China; Department of Chemistry, University of Connecticut, Storrs, CT 06269-3060, USA. Electronic address: jingouyang@csu.edu.cn.
² Centre for Mineral Materials, School of Minerals Processing and Bioengineering, Central South University, Changsha 410083, China; Hunan Key Lab of Mineral Materials and Application, Central South University, Changsha 410083, China; Key Lab of Clay Mineral Functional Materials in China Building Materials Industry, Changsha 410083, China.
³ Department of Chemistry, University of Connecticut, Storrs, CT 06269-3060, USA.
⁴ Department of Chemistry, University of Connecticut, Storrs, CT 06269-3060, USA. Electronic address: steven.suib@uconn.edu.

PMID: 30502573
DOI: 10.1016/j.jhazmat.2018.11.083

Abstract

Macroporous CeO₂-ZrO₂ (CZ) solid solutions with gradually changing ceria content were prepared through the EISA method. Pore sizes of the samples are about 100 nm-1 μm and pore walls are 100 nm-1.5 μm. The surface and near surface reduction bands of Ce⁴⁺ below 600 °C were maximized for the Ce_0.5Zr_0.5O₂ sample (C5) according to the quantitative de-convolution to the acquired TPR curves. The area percentage of the O^2-2p⁶ → Ce³⁺3d⁹4f² electronic transition band on XPS spectra, which related to the concentration of the Ce³⁺, was found to be a function of the ceria content. The oxygen storage capacity showed a positive relationship with the chemical compositions. Redox reactions below 600 °C play a key role in determining the reduction performances of ceria based TWCs. Three-way catalytic performances of the Pd + Rh + Pt /C5 sample showed an ignition temperature for CO and NOx at about 240 °C, and finished before 300 °C. The ignition of C₃H₈ started at 270 °C while finished at differed samples. The maximum catalytic efficiencies of CO, NOx, and C₃H₈ on C5 sample were revealed to 100%, 98%, and 97%, respectively. The performances showed that porous CZ solid solutions are suitable for high performance catalytic applications.

Keywords: Macroporous CZ solid solution; Oxygen storage capacity; Reduction performance; Textual property.