title: Mechanistic insights into heterogeneous methane activation.
abstract: While natural gas is an abundant chemical fuel, its low volumetric energy density has prompted a search for catalysts able to transform methane into more useful chemicals. This search has often been aided through the use of transition state (TS) scaling relationships, which estimate methane activation TS energies as a linear function of a more easily calculated descriptor, such as final state energy, thus avoiding tedious TS energy calculations. It has been shown that methane can be activated via a radical or surface-stabilized pathway, both of which possess a unique TS scaling relationship. Herein, we present a simple model to aid in the prediction of methane activation barriers on heterogeneous catalysts. Analogous to the universal radical TS scaling relationship introduced in a previous publication, we show that a universal TS scaling relationship that transcends catalysts classes also seems to exist for surface-stabilized methane activation if the relevant final state energy is used. We demonstrate that this scaling relationship holds for several reducible and irreducible oxides, promoted metals, and sulfides. By combining the universal scaling relationships for both radical and surface-stabilized methane activation pathways, we show that catalyst reactivity must be considered in addition to catalyst geometry to obtain an accurate estimation for the TS energy. This model can yield fast and accurate predictions of methane activation barriers on a wide range of catalysts, thus accelerating the discovery of more active catalysts for methane conversion.
authors.affiliation: SUNCAT Center for Interface Science and Catalysis, Department of Chemical Engineering, Stanford University, 450 Serra Mall Stanford, California 94305, USA. norskov@stanford.edu.
authors.forename: Allegra A
authors.identifier: http://orcid.org/0000-0003-3048-6593
authors.initials: AA
authors.lastname: Latimer
authors.affiliation: SUNCAT Center for Interface Science and Catalysis, Department of Chemical Engineering, Stanford University, 450 Serra Mall Stanford, California 94305, USA. norskov@stanford.edu.
authors.forename: Hassan
authors.initials: H
authors.lastname: Aljama
authors.affiliation: SUNCAT Center for Interface Science and Catalysis, Department of Chemical Engineering, Stanford University, 450 Serra Mall Stanford, California 94305, USA. norskov@stanford.edu.
authors.forename: Arvin
authors.initials: A
authors.lastname: Kakekhani
authors.affiliation: SUNCAT Center for Interface Science and Catalysis, Department of Chemical Engineering, Stanford University, 450 Serra Mall Stanford, California 94305, USA. norskov@stanford.edu.
authors.forename: Jong Suk
authors.initials: JS
authors.lastname: Yoo
authors.affiliation: SUNCAT Center for Interface Science and Catalysis, Department of Chemical Engineering, Stanford University, 450 Serra Mall Stanford, California 94305, USA. norskov@stanford.edu.
authors.forename: Ambarish
authors.initials: A
authors.lastname: Kulkarni
authors.affiliation: SUNCAT Center for Interface Science and Catalysis, Department of Chemical Engineering, Stanford University, 450 Serra Mall Stanford, California 94305, USA. norskov@stanford.edu.
authors.forename: Charlie
authors.initials: C
authors.lastname: Tsai
authors.affiliation: SUNCAT Center for Interface Science and Catalysis, Department of Chemical Engineering, Stanford University, 450 Serra Mall Stanford, California 94305, USA. norskov@stanford.edu.
authors.forename: Max
authors.identifier: http://orcid.org/0000-0003-1348-4692
authors.initials: M
authors.lastname: Garcia-Melchor
authors.affiliation: SUNCAT Center for Interface Science and Catalysis, Department of Chemical Engineering, Stanford University, 450 Serra Mall Stanford, California 94305, USA. norskov@stanford.edu and SUNCAT Center for Interface Science and Catalysis, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, USA.
authors.forename: Frank
authors.initials: F
authors.lastname: Abild-Pedersen
authors.affiliation: SUNCAT Center for Interface Science and Catalysis, Department of Chemical Engineering, Stanford University, 450 Serra Mall Stanford, California 94305, USA. norskov@stanford.edu and SUNCAT Center for Interface Science and Catalysis, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, USA.
authors.forename: Jens K
authors.initials: JK
authors.lastname: Nørskov