Redox Pathways for HCOOH Decomposition over CeO2 Surfaces
- ORNL
The reaction of HCOOH, the simplest C-1 carboxylic acid, has been studied on oxidized (CeO{sub 2}) and reduced cerium oxide (CeO{sub x}) thin films. HCOOH has been proposed as an important C1 precursor to the formation of CO{sub 2} and H{sub 2} in the water-gas-shift (WGS) reaction, in which ceria is also used as a stable support rich in oxygen. The HCOOH is observed to adsorb by way of a formate intermediate species (HCOO{sup -}) through the dissociation of the acidic H over both CeO{sub 2} (Ce{sup 4+}) and CeO{sub x} (Ce{sup 4+}/Ce{sup 3+}) surfaces. On the fully oxidized CeO{sub 2} surface, this H species reacts with surface O and desorbs as H{sub 2}O when the temperature is <300 K. In addition to water, temperature programmed desorption spectra indicate the evolution of CO{sub 2} and H{sub 2} between 350 and 400 K followed by CO desorption in two regimes at 450 and 525 K. On reduced ceria, only CO and H{sub 2} were produced between 450 and 600 K. The reaction of HCOOH with ceria therefore leads to both the reduction of the oxide, through the formation of H{sub 2}O and CO{sub 2}, and oxidation of the oxide, through decomposition to H{sub 2} and CO, depending on the initial state of the ceria. C K-edge near-edge X-ray absorption fine structure and soft X-ray photoelectron spectroscopy indicate that formate and -OH were the only surface intermediates.
- Research Organization:
- Oak Ridge National Laboratory (ORNL)
- Sponsoring Organization:
- SC USDOE - Office of Science (SC)
- DOE Contract Number:
- AC05-00OR22725
- OSTI ID:
- 941598
- Journal Information:
- Journal of Physical Chemistry C, Journal Name: Journal of Physical Chemistry C Journal Issue: 26 Vol. 112; ISSN 1932-7447
- Country of Publication:
- United States
- Language:
- English
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