Methane oxidation on Pd–Ceria: A DFT study of the mechanism over PdxCe1-xO2, Pd, and PdO

Journal Article · Mon Feb 14 00:00:00 EST 2011 · Journal of Catalysis

DOI:https://doi.org/10.1016/j.jcat.2010.11.006· OSTI ID:1380414

Mayernick, Adam D.; Janik, Michael J.

Palladium/ceria exhibits unique catalytic activity for hydrocarbon oxidation; however, the chemical and structural properties of active sites on the palladium–ceria surface are difficult to characterize. Strong interactions between palladium and the ceria support stabilize oxidized Pdδ+ species, which may contribute to the significant activity of Pd/ceria for methane oxidation. We present a density functional theory (DFT + U) investigation into methane oxidation over Pd/ceria and quantify the activity of the Pd_xCe_1-xO₂(1 1 1) mixed oxide surface in comparison with the PdO(1 0 0) and Pd(1 1 1) surfaces. The methane activation barrier is lowest over the Pd_xCe_1-xO₂(1 1 1) surface, even lower than over the Pd(1 1 1) surface or low coordinated stepped or kinked Pd sites. Subsequent reaction steps in complete oxidation, including product desorption and vacancy refilling, are considered to substantiate that methane activation remains the rate-limiting step despite the low barrier over Pd_xCe_1-xO₂(1 1 1). The low barrier over the Pd_xCe_1-xO₂(1 1 1) surface demonstrates that mixed ceria-noble metal oxides offer the potential for improved hydrocarbon oxidation performance with respect to dispersed noble metal particles on ceria.

• Research Organization: Energy Frontier Research Centers (EFRC) (United States). Center for Atomic-Level Catalyst Design (CALCD)
• Sponsoring Organization: USDOE Office of Science (SC), Basic Energy Sciences (BES)
• DOE Contract Number: SC0001058
• OSTI ID: 1380414
• Journal Information: Journal of Catalysis, Vol. 278, Issue 1; Related Information: CALCD partners with Louisiana State University (lead); Clemson University; University of Florida; Georgia Institute of Technology; Grambling State University; Oak Ridge National Laboratory; Ohio State University; Pennsylvania State; Texas A&M University; Vienna University of Technology, Austria; University of Utrecht, Netherlands; ISSN 0021-9517
• Publisher: Elsevier
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
catalysis (heterogeneous)
hydrogen and fuel cells
charge transport
carbon capture
carbon sequestration
materials and chemistry by design
synthesis (novel materials)