Chemisorption and reaction of sulfur dioxide with oxidized and reduced ceria surfaces

Journal Article · Thu Dec 23 04:00:00 EST 1999 · Journal of Physical Chemistry B: Materials, Surfaces, Interfaces, amp Biophysical

DOI:https://doi.org/10.1021/jp992240a· OSTI ID:20015207

Overbury, S H; Mullins, D R; Huntley, D R; Kundakovic, L

The interaction of SO{sub 2} with highly oriented ceria films is studied as a function of coverage, temperature, and degree of oxidation of the ceria. Soft X-ray photoemission (SXPS) is used to analyze the oxidation state of the ceria and the evolution of the SO{sub 2}-derived species, while thermal desorption spectroscopy is used to analyze the desorption products. The principle interaction is chemisorption of SO{sub 2} at oxygen anions, which reversibly desorbs as SO{sub 2} over a broad temperature range from 200 to 600 K. This interaction is characterized as a Lewis acid-base interaction and occurs with approximately equal facility if the surface is hydroxylated or sulfided. On reduced ceria the adsorption is more heterogeneous, suggesting a variety of local bonding environments, including a small, distinguishable amount of adsorption at Ce{sup 3+} sites. A significant portion of the chemisorbed SO{sub 2} converts to sulfide above 300 K, and the resulting sulfide then equilibrates between bulk and surface sites above 600 K. Adsorption at a sulfide site leads to a 1.5 eV shift in the sulfide S 2p state toward higher binding energy. Thermal conversion of chemisorbed SO{sub 2} to sulfate is not observed. The results are compared with previous studies of NO adsorption on ceria films and with similar studies of SO{sub 2} chemisorption on titania.

• Research Organization: Oak Ridge National Lab., TN (US)
• Sponsoring Organization: US Department of Energy
• DOE Contract Number: AC05-96OR22464; AC02-98CH10886
• OSTI ID: 20015207
• Journal Information: Journal of Physical Chemistry B: Materials, Surfaces, Interfaces, amp Biophysical, Journal Name: Journal of Physical Chemistry B: Materials, Surfaces, Interfaces, amp Biophysical Journal Issue: 51 Vol. 103; ISSN 1089-5647; ISSN JPCBFK
• Country of Publication: United States
• Language: English

Related Subjects

33 ADVANCED PROPULSION SYSTEMS
54 ENVIRONMENTAL SCIENCES
AIR POLLUTION CONTROL
CATALYSTS
CATALYTIC CONVERTERS
CERIUM
CHEMISORPTION
EXHAUST GASES
SULFUR DIOXIDE