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The relationship between chemical state of Pd species and catalytic activity of methane combustion on Pd/CeO2

Abstract

Three Pd/CeO2 catalysts are synthesized by reduction-deposition and impregnation method (IMP) to clarify how the chemical state of Pd influence the catalytic performance for CH4 combustion. The results show that Pd/CeO2 (HHA), using hydrazine hydrate as reductant, behaves much higher catalytic activity and stability for CH4 combustion than that of Pd/CeO2 (FA), using formaldehyde as reductant, and Pd/CeO2 (IMP). Our comprehensive characterization results reveal there are two different chemical state of Pd species on Pd/CeO2: Pd2+ in the form of PdO particles and Pdδ+ (2 < δ ≤ 4) in the form of PdxCe1-xO2, and the latter is mainly induced by the Pd species entering the lattice of CeO2, which acting as a transfer channel of active oxygen species from CeO2 lattice to active Pd species. The activities of Pd/CeO2 directly correlates to the surface concentrations of PdO and adsorbed oxygen. The increasing of PdxCe1-xO2 amount would thicken the transition layer and decrease replenishing rate of oxygen vacancy through diffusion of lattice oxygen. Meanwhile, the existence of more PdxCe1-xO2 could promote the capture of produced CO2 on the CeO2 around Pd species and decrease catalytic activity.

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Publication details

The article was received on 28 Jan 2018, accepted on 06 Apr 2018 and first published on 06 Apr 2018


Article type: Paper
DOI: 10.1039/C8CY00208H
Citation: Catal. Sci. Technol., 2018, Accepted Manuscript
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    The relationship between chemical state of Pd species and catalytic activity of methane combustion on Pd/CeO2

    J. Ma, Y. Lou, Y. Cai, Z. Zhao, L. Wang, W. Zhan, Y. Guo and Y. Guo, Catal. Sci. Technol., 2018, Accepted Manuscript , DOI: 10.1039/C8CY00208H

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