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Elucidation of the Active Phase in Pd‐Based Catalysts Supporting on Octahedral CeO 2 for Low‐Temperature Methane Oxidation
Author(s) -
Wu Mingwei,
Li Wenzhi,
Zhang Xia,
Xue Fengyang,
Yang Tao,
Yuan Liang
Publication year - 2021
Publication title -
chemistryselect
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.437
H-Index - 34
ISSN - 2365-6549
DOI - 10.1002/slct.202100511
Subject(s) - catalysis , anaerobic oxidation of methane , methane , palladium , calcination , redox , chemistry , catalytic combustion , oxidative coupling of methane , metal , inorganic chemistry , octahedron , adsorption , phase (matter) , crystallography , organic chemistry , crystal structure
Pd catalysts supported on CeO 2 (Pd/CeO 2 ) are highly active towards lean methane combustion, and the catalytic behavior is substantially affected by the chemical property of surface palladium species. In this work, various Pd catalysts supported on octahedral‐CeO 2 (Pd/O‐CeO 2 ) were successfully prepared by redox interation‐engaged strategy. The oxidation state of palladium species was controlled by varying the calcination condition. X‐ray absorption characterization coupled with light‐off curves confirmed that the catalytic activity of relevant catalysts was closely related with the proportion of the metallic Pd and PdO species. Within limits, increasing Pd 0 /PdO ratio can bring superior catalytic behavior and the approximately equal ratio of interfacial hybrid Pd 0 /PdO phase exhibits the optimal catalytic activity. Importantly, in situ DRIFTS results demonstrated that the hybrid Pd 0 /PdO phase was recognized as the active site pair for lean methane oxidation, which is attributed to the fact that the metallic Pd 0 species can adsorb and dissociate methane molecules and then the resulting intermediate species further react with the active O* of PdO, which thereby promotes CH 4 activation.