期刊
JOURNAL OF CATALYSIS
卷 407, 期 -, 页码 104-114出版社
ACADEMIC PRESS INC ELSEVIER SCIENCE
DOI: 10.1016/j.jcat.2022.01.023
关键词
Size effect; Pd/CeO2; CO oxidation; CO-PROX; Catalytic mechanism
资金
- Natural Science Foundation of Zhejiang Province [LQ20B030007]
- National Natural Science Foundation of China [22102146]
- State Key Laboratory of Catalysis in DICP [N-20-07]
- Zhejiang Normal University [2021ZS0602]
- National Innovation and Entrepreneurship Training Program for College Students [202010345022]
Supported metal catalysts are widely used in industrial processes, and the size of the metal particles is crucial for the catalytic performance. This study investigates CeO2-supported Pd catalysts with different Pd size regimes and reveals that single Pd atoms supported on CeO2 have the highest intrinsic activity in CO oxidation and promote the CO-PROX reaction due to a stronger H-spillover effect.
Supported metal catalysts are the most widely used in industrial processes and the metal particle size plays a crucial factor in determining the catalytic performance. Herein, CeO2-supported Pd catalysts with different Pd size regimes ranging from single atoms, to nanoclusters (1-2 nm), and to nanoparticles (> 2 nm) were used for both CO oxidation and preferential oxidation of CO in H-2 (CO-PROX). Compared to Pd nanoclusters and nanoparticles, CeO2-supported single Pd atoms (Pd-SA/CeO2) are the most intrinsically active in CO oxidation, with an apparent activation energy of ca. 40 kJ mol(-1). Results of kinetic investigations and in situ diffuse reflectance infrared Fourier transformed spectroscopy demonstrate the CO oxidation proceeding through a Langmuir-Hinshelwood mechanism with the decomposition of formate species acting dominantly as the rate-determining step. The CO reaction rate is exclusively promoted on Pd-SA/CeO2 catalysts for the CO-PROX reaction, which could be ascribed to a stronger H-spillover effect on isolated Pd sites to produce bridged-OH on CeO2 surface, simultaneously facilitating the consumptions of bicarbonate and formate species. There results greatly deepen the fundamental understanding of the Pd size regimes over Pd/CeO2 catalysts for the oxidation of CO. (c) 2022 Elsevier Inc. All rights reserved.
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