Effects of Zr substitution on soot combustion over cubic fluorite-structured nanoceria: Soot-ceria contact and interfacial oxygen evolution.
Peng Liu, Xiaoliang Liang, Yanliu Dang, Junkai He, Alireza Shirazi-Amin, Laura A Achola, Shanka Dissanayake, Hanlin Chen, Mingli Fu, Daiqi Ye, Steven L Suib
Author Information
Peng Liu: School of Environment and Energy, South China University of Technology, Guangzhou 510006, China; Department of Chemistry, University of Connecticut, Storrs, Connecticut 06269, USA; University of Chinese Academy of Sciences, Beijing 100049, China.
Xiaoliang Liang: CAS Key Laboratory of Mineralogy and Metallogeny/Guangdong Provincial Key Laboratory of Mineral Physics and Materials, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China; University of Chinese Academy of Sciences, Beijing 100049, China. Electronic address: liangxl@gig.ac.cn.
Yanliu Dang: Institute of Materials Science, University of Connecticut, Storrs, Connecticut 06269, USA.
Junkai He: Institute of Materials Science, University of Connecticut, Storrs, Connecticut 06269, USA.
Alireza Shirazi-Amin: Department of Chemistry, University of Connecticut, Storrs, Connecticut 06269, USA.
Laura A Achola: Department of Chemistry, University of Connecticut, Storrs, Connecticut 06269, USA.
Shanka Dissanayake: Department of Chemistry, University of Connecticut, Storrs, Connecticut 06269, USA.
Hanlin Chen: Guangdong Provincial Key Laboratory of Petrochemical Pollution Processes and Control, School of Environmental Science and Engineering, Guangdong University of Petrochemical Technology, Maoming 525000, China.
Mingli Fu: School of Environment and Energy, South China University of Technology, Guangzhou 510006, China.
Daiqi Ye: School of Environment and Energy, South China University of Technology, Guangzhou 510006, China.
Steven L Suib: Institute of Materials Science, University of Connecticut, Storrs, Connecticut 06269, USA; Department of Chemistry, University of Connecticut, Storrs, Connecticut 06269, USA. Electronic address: steven.suib@uconn.edu.
Ceria is widely used as a catalyst for soot combustion, but effects of Zr substitution on the reaction mechanism is ambiguous. The present work elucidates effects of Zr substitution on soot combustion over cubic fluorite-structured nanoceria. The nanostructured CeO, CeZrO, and CeZrO composed of 5-6 nm crystallites display T (the temperature at maximum CO yield) at 383, 355, and 375°C under 10 vol.% O/N, respectively. The size of agglomerate decreases from 165.5 to 51.9-57.3 nm, which is beneficial for the soot-ceria contact. Moreover, Zr increases the amount of surface oxygen vacancies, generating more active oxygen (O and O) for soot oxidation. Thus, the activities of CeZrO and CeZrO in soot combustion are better than that of CeO. Although oxygen vacancies promote the migration of lattice O, the enriched surface Zr also inhibits the mobility of lattice O. Therefore, the T of CeZrO is higher than that of CeZrO. Based on reaction kinetic study, soot in direct contact with ceria preferentially decomposes with low activation energy, while the oxidation of isolated soot occurs through diffusion with high activation energy. The obtained findings provide new understanding on the soot combustion over nanoceria.
