title: The Effect of Exposed Facets of Ceria to the Nickel Species in Nickel-Ceria Catalysts and Their Performance in a NO + CO Reaction.
abstract: CeO2 rods with {110} facets and cubes with {100} facets were utilized as catalyst supports to probe the effect of crystallographic facets on the nickel species and the structure-dependent catalytic performance. Various analysis methods (ex and in situ XRD, TEM, Raman, XPS, TPR, TPD) were used to investigate the structural forms of the catalysts, and these results indicated that the deposition of nickel species resulted in the formation of two main active types of the catalyst components: NiO strongly or weakly interacted with the surface and Ni-Ce-O solid solution. Notably, the states and distribution ratio of nickel species were related to the shape of CeO2. It was found that CeO2 rods had more active sites to coordinate with nickel species to form a strong interaction with NiO on the surface and a more stable construction when compared to cubes. Furthermore, the nickel-ceria catalysts with rod shape were more active towards NO oxidation with complete conversion below 191 °C, but for cube shape, complete conversion occurred above 229 °C (e.g., for nickel loading of ∼5%, the complete conversion temperature was 154 °C for the rod shape and 229 °C for the cube shape). On the basis of the analysis of the catalysts structure, the superior catalytic activity was due to a combination of surface structures of NiO (mainly strongly interacting with the surface) and nickel ions Ni(2+) in the Ni-Ce-O bulk phase.
authors.affiliation: Key Laboratory for Special Functional Aggregate Materials of Education Ministry, School of Chemistry and Chemical Engineering, Shandong University , Jinan, 250100, P. R. China.
authors.forename: Ke
authors.initials: K
authors.lastname: Tang
authors.affiliation: Key Laboratory for Special Functional Aggregate Materials of Education Ministry, School of Chemistry and Chemical Engineering, Shandong University , Jinan, 250100, P. R. China.
authors.forename: Wei
authors.initials: W
authors.lastname: Liu
authors.affiliation: Key Laboratory for Special Functional Aggregate Materials of Education Ministry, School of Chemistry and Chemical Engineering, Shandong University , Jinan, 250100, P. R. China.
authors.forename: Jing
authors.initials: J
authors.lastname: Li
authors.affiliation: Key Laboratory for Special Functional Aggregate Materials of Education Ministry, School of Chemistry and Chemical Engineering, Shandong University , Jinan, 250100, P. R. China.
authors.forename: Jinxin
authors.initials: J
authors.lastname: Guo
authors.affiliation: Key Laboratory for Special Functional Aggregate Materials of Education Ministry, School of Chemistry and Chemical Engineering, Shandong University , Jinan, 250100, P. R. China.
authors.forename: Jingcai
authors.initials: J
authors.lastname: Zhang
authors.affiliation: Key Laboratory for Special Functional Aggregate Materials of Education Ministry, School of Chemistry and Chemical Engineering, Shandong University , Jinan, 250100, P. R. China.
authors.forename: Shuping
authors.initials: S
authors.lastname: Wang
authors.affiliation: School of Energy and Power Engineering, Shandong University , Jinan, 250061, P. R. China.
authors.forename: Shengli
authors.initials: S
authors.lastname: Niu
authors.affiliation: Key Laboratory for Special Functional Aggregate Materials of Education Ministry, School of Chemistry and Chemical Engineering, Shandong University , Jinan, 250100, P. R. China.
authors.forename: Yanzhao
authors.initials: Y
authors.lastname: Yang
keywords: NO + CO reaction; crystallographic facets; multicomponent catalyst; nickel species; nickel-ceria catalyst