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Oxygen Vacancy-Assisted Coupling and Enolization of Acetaldehyde on CeO2(111).
- Source :
-
Journal of the American Chemical Society . 10/31/2012, Vol. 134 Issue 43, p18034-18045. 12p. - Publication Year :
- 2012
-
Abstract
- The temperature-dependent adsorption and reaction of acetaldehyde (CH3CHO) on a fully oxidized and a highly reduced thin-film CeO2(111) surface have been investigated using a combination of reflection-absorption infrared spectroscopy (RAIRS) and periodic density functional theory (DFT+U) calculations. On the fully oxidized surface, acetaldehyde adsorbs weakly through its carbonyl O interacting with a lattice Ce4+ cation in the η1-O configuration. This state desorbs at 210 K without reaction. On the highly reduced surface, new vibrational signatures appear below 220 K. They are identified by RAIRS and DFT as a dimer state formed from the coupling of the carbonyl O and the acyl C of two acetaldehyde molecules. This dimer state remains up to 400 K before decomposing to produce another distinct set of vibrational signatures, which are identified as the enolate form of acetaldehyde (CH2CHO-). Furthermore, the calculated activation barriers for the coupling of acetaldehyde, the decomposition of the dimer state, and the recombinative desorption of enolate and H as acetaldehyde are in good agreement with previously reported TPD results for acetaldehyde adsorbed on reduced CeO2(111) [Chen et al. J. Phys. Chem. C2011, 115, 3385]. The present findings demonstrate that surface oxygen vacancies alter the reactivity of the CeO2(111) surface and play a crucial role in stabilizing and activating acetaldehyde for coupling reactions. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 00027863
- Volume :
- 134
- Issue :
- 43
- Database :
- Academic Search Index
- Journal :
- Journal of the American Chemical Society
- Publication Type :
- Academic Journal
- Accession number :
- 83372116
- Full Text :
- https://doi.org/10.1021/ja3074243