| Autor: |
Ferrizz, R., Gorte, R.J., Vohs, J.M. |
| Zdroj: |
Catalysis Letters; September 2002, Vol. 82 Issue: 1-2 p123-129, 7p |
| Abstrakt: |
The interaction of SO2with model thin-film ceria catalysts was studied using temperature-programmed desorption (TPD) and X-ray photoelectron spectroscopy (XPS). During TPD of ceria samples that had been exposed to SO2at room temperature, SO2desorbed in peaks centered at 473, 883 and 963 K. The lower temperature peak is associated with molecularly adsorbed SO2, while the higher temperature peaks are due to decomposition of adsorbed sulfates. XPS results show that at room temperature a small fraction of the adsorbed SO2is oxidized to SO42-using oxygen supplied by the ceria. This reaction also results in partial reduction of the ceria surface. High coverages of surface sulfate species could be produced by exposing the ceria samples to mixtures of SO2and O2at 573 K. In addition to producing gaseous SO2, thermal decomposition of surface sulfates at temperatures above 823 K resulted in the formation of an oxy-sulfide (Ce2O2S) on the ceria surface. |
| Databáze: |
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