Methane Activation at the Metal-Support Interface of Ni 4 -CeO 2 (111) Catalyst

A Theoretical Study

Rajib Kumar Singha, Yuta Tsuji, Muhammad Haris Mahyuddin, Kazunari Yoshizawa

Research output: Contribution to journalArticle

Abstract

Methane activation is usually assumed to take place on top of metal surfaces or metal clusters. It can also occur at the metal-support interface in metal-supported catalysts with reducible oxides, such as CeO 2 . In the present work, we exploit density functional theory with an additional Hubbard-like parameter (DFT + U) to calculate the activation of methane at an O site interfacing a Ni 4 metal cluster on a support, CeO 2 (111) surface. Two reaction routes, namely, radical and nonradical routes, are taken into account. We show that the nonradical route is favored with an apparent activation energy of 18.1 kcal/mol, which is lower than that for the radical route by 15.0 kcal/mol. In the nonradical route, the formation of a four-centered transition-state structure is observed while a C-H bond of methane is being cleaved to form an OH moiety and a CH 3 fragment that is being bound to the interfacial Ni atom. It is also found that the interfacial O atoms are out of the CeO 2 surface plane with Ce-O bond distances being much longer than those in the crystalline bulk CeO 2 , which allows them to be easily reduced, and hence, the interfacial O atoms become more reactive toward methane, as compared to the surface O atoms. The interactions between Ni 4 cluster and the CeO 2 (111) surface result in the reduction of two Ce 4+ ions to Ce 3+ , improving the reducibility of the interfacial O atoms. This should be an important key to the facile methane activation.

Original languageEnglish
Pages (from-to)9788-9798
Number of pages11
JournalJournal of Physical Chemistry C
Volume123
Issue number15
DOIs
Publication statusPublished - Apr 18 2019

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Methane
methane
Metals
Chemical activation
routes
activation
catalysts
Atoms
Catalysts
metals
atoms
metal clusters
Catalyst supports
Discrete Fourier transforms
Oxides
metal surfaces
Density functional theory
Activation energy
fragments
methylidyne

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Energy(all)
  • Physical and Theoretical Chemistry
  • Surfaces, Coatings and Films

Cite this

Methane Activation at the Metal-Support Interface of Ni 4 -CeO 2 (111) Catalyst : A Theoretical Study. / Singha, Rajib Kumar; Tsuji, Yuta; Mahyuddin, Muhammad Haris; Yoshizawa, Kazunari.

In: Journal of Physical Chemistry C, Vol. 123, No. 15, 18.04.2019, p. 9788-9798.

Research output: Contribution to journalArticle

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