Methane oxidation over palladium oxide. From electronic structure to catalytic conversion
Doktorsavhandling, 2017

Understanding how catalysts work down to the atomic level can provide ways to improve chemical processes on which our contemporary economy is heavily reliant. The oxidation of methane is one such example, which is important from an environmental point of view. Methane is a potent greenhouse gas and natural and biogas vehicles need efficient catalysts to prevent slip of uncombusted fuel into the exhaust. Commercial catalysts for methane oxidation are often based on palladium or platinum. Metallic palladium, however, is easily converted to palladium oxide when the engine is operated at oxygen rich conditions. In this thesis, various aspects of complete methane oxidation over PdO(101) are investigated with computational methods based on density functional theory (DFT). PdO(101) is the active surface for methane oxidation, and firstly, the reaction intermediates CO and H are studied in detail. Possible pathways for H2 adsorption, dissociation and eventual water formation are investigated, in connection to core-level spectroscopy experiments. Similarly, the adsorption configurations for carbon monoxide on clean and oxidized palladium are examined with a combination of DFT calculations, core-level and infrared spectroscopy. Secondly, a detailed kinetic model is constructed that describes the catalytic conversion of CH4 to CO2 and H2O over PdO(101). This is done in a first-principles microkinetics framework, where the kinetic parameters are obtained by applying density functional and transition state theory. The kinetic model provides a fundamental understanding of findings from reactor experiments, such as the rate limiting steps and poisoning behaviour, and shows qualitatively different behaviour of adsorbates on oxide as compared to metal surfaces. Lastly, limitations of the commonly used class of generalized gradient functionals are illustrated in the computation of several properties of adsorbates on metal oxide surfaces. These include core-level shifts and thermodynamic and reactive properties of adsorbates on the PdO(101) surface. Similarly, the description of several molecular and cooperative adsorption processes are also found to be sensitive to the applied exchange-correlation functional on the BaO(100), TiO2(110) and CeO2(111) surfaces.

methane oxidation

microkinetic modelling

palladium oxide

density functional theory

PdO(101)

core-level spectroscopy

heterogeneous catalysis

PJ-salen, Fysikgården 2B.
Opponent: Dr. María Verónica Ganduglia-Pirovano, Department of Applied Catalysis, Instute of Catalysis and Petrochemistry, Madrid, Spain.

Författare

Maxime van den Bossche

Chalmers

Chalmers, Fysik, Kemisk fysik

Kompetenscentrum katalys (KCK)

Methane Oxidation over PdO(101) Revealed by First-Principles Kinetic Modeling

Journal of the American Chemical Society,; Vol. 137(2015)p. 12035-12044

Artikel i vetenskaplig tidskrift

Reversed Hysteresis during CO Oxidation over Pd75Ag25(100)

ACS Catalysis,; Vol. 6(2016)p. 4154-4161

Artikel i vetenskaplig tidskrift

Effects of non-local exchange on core level shifts for gas-phase and adsorbed molecules

Journal of Chemical Physics,; Vol. 141(2014)

Artikel i vetenskaplig tidskrift

Dissociative Adsorption of Hydrogen on PdO(101) Studied by HRCLS and DFT

Journal of Physical Chemistry C,; Vol. 117(2013)p. 13510-13519

Artikel i vetenskaplig tidskrift

Intrinsic Ligand Effect Governing the Catalytic Activity of Pd Oxide Thin Films

ACS Catalysis,; Vol. 4(2014)p. 3330-3334

Artikel i vetenskaplig tidskrift

CO Adsorption on Clean and Oxidized Pd(111)

Journal of Physical Chemistry C,; Vol. 118(2014)p. 1118-1128

Artikel i vetenskaplig tidskrift

Van den Bossche, M., Grönbeck H., "Adsorbate pairing on oxide surfaces: influence on reactivity and dependence on the oxide, adsorbate pair and density functional."

Ämneskategorier

Oorganisk kemi

Fysikalisk kemi

Annan kemiteknik

Annan fysik

Annan kemi

Teoretisk kemi

Den kondenserade materiens fysik

Styrkeområden

Nanovetenskap och nanoteknik

Transport

Materialvetenskap

Infrastruktur

C3SE (Chalmers Centre for Computational Science and Engineering)

ISBN

978-91-7597-545-0

Doktorsavhandlingar vid Chalmers tekniska högskola. Ny serie: 4226

Utgivare

Chalmers tekniska högskola

PJ-salen, Fysikgården 2B.

Opponent: Dr. María Verónica Ganduglia-Pirovano, Department of Applied Catalysis, Instute of Catalysis and Petrochemistry, Madrid, Spain.