at Google ScholarTitle data
Koch, Gregor ; Hävecker, Michael ; Teschner, Detre ; Carey, Spencer J. ; Wang, Yuanqing ; Kube, Pierre ; Hetaba, Walid ; Lunkenbein, Thomas ; Auffermann, Gudrun ; Timpe, Olaf ; Rosowski, Frank ; Schlögl, Robert ; Trunschke, Annette:
Surface Conditions That Constrain Alkane Oxidation on Perovskites.
In: ACS Catalysis.
Vol. 10
(2020)
Issue 13
.
- pp. 7007-7020.
ISSN 2155-5435
DOI: https://doi.org/10.1021/acscatal.0c01289
Abstract in another language
The crystal structure of perovskites can incorporate a wide variety of cations, which makes this class of materials so interesting for studies of links between solid-state chemistry and catalysis. Perovskites are known as typical total combustion catalysts in hydrocarbon oxidation reactions. The fundamental question that we investigate here is whether surface modifications of perovskites can lead to the formation of valuable reaction products in alkane oxidation. We studied the effect of segregated two-dimensional surface nanostructures on selectivity to propene in the oxidative dehydrogenation of propane. Manganese-based perovskites AMnO(3) (A = La, Sm) were prepared by combustion and hydrothermal synthesis. Bulk and surface structures were investigated by X-ray diffraction, temperature-programmed reduction, aberration-corrected scanning transmission electron microscopy (STEM), multiwavelength Raman, and ambient-pressure X-ray photoelectron spectroscopy (AP-XPS) in combination with near-edge X-ray absorption fine structure (NEXAFS) spectroscopy. Surface oxygen species responsible for C-H activation were distinguished by AP-XPS on the basis of a rigorous in situ analysis of the O is spectra recorded under a broad range of reaction conditions. Signals at 529.2, 530.1, 530.9, 531.2, and 531.8 eV were attributed to lattice O, defect-affected O, surface O, oxygen in carbonates, and hydroxyl groups, respectively. Operando AP-XPS revealed critical surface features, which occur under catalyst operation. The catalyst performance depends on the synthesis technique and the reaction conditions. In presence of a two-dimensional MnOx surface phase, addition of steam to the feed resulted in an increase in selectivity to the partial oxidation product propene to practically relevant values. The selectivity increase is related to the presence of Mn in a low oxidation state (2+/3+), an increased concentration of hydroxyl groups, and a higher abundance of adsorbed activated oxygen species on the catalyst surface. The surface analysis of a working catalyst highlights the importance of the termination layer of polycrystalline perovskites as a genuine property implemented by catalyst preparation. Such a termination layer controls the chemical properties and reactivity of perovskites. The information provides input for the development of realistic models that can be used by theory to predict functional properties.
Further data
| Item Type: | Article in a journal |
|---|---|
| Refereed: | Yes |
| Additional notes: | WOS:000547452800003 |
| Institutions of the University: | Faculties > Faculty of Biology, Chemistry and Earth Sciences > Department of Chemistry Faculties Faculties > Faculty of Biology, Chemistry and Earth Sciences Faculties > Faculty of Biology, Chemistry and Earth Sciences > Department of Chemistry > Chair Operando-Analytics of Electrochemical Energy Storage > Chair Operando-Analytics of Electrochemical Energy Storage - Univ.-Prof. Dr. Thomas Lunkenbein Faculties > Faculty of Biology, Chemistry and Earth Sciences > Department of Chemistry > Chair Operando-Analytics of Electrochemical Energy Storage |
| Result of work at the UBT: | No |
| DDC Subjects: | 500 Science > 540 Chemistry |
| Date Deposited: | 13 Jun 2025 07:08 |
| Last Modified: | 04 Jul 2025 11:32 |
| URI: | https://eref.uni-bayreuth.de/id/eprint/93700 |