Adsorption and decomposition of acetic acid on CeO2(111) surfaces

CALAZA, FLORENCIA C.; CHEN, TSUNG-LIANG; MULLINS, DAVID R.; OVERBURY, STEVEN H.

Denver, CO

Conferencia; 242nd ACS National Meeting; 2011

AMERICAN CHEMICAL SOCIETY

The reactivity of acetic acid on CeO2(111) thin films was studied on fully oxidized surfaces as well as on reduced ceria surfaces CeO2-d (where d=0.18-0.3). The molecule readily chemisorbs in UHV on both of these surfaces by breaking its OH bond and leaving adsorbed acetate. The surface intermediates were determined by s-XPS and NEXAFS as a function of temperature and ceria reduction. Some acetate species convert to carbanion-enolate during decomposition. On CeO2(111), above 500 K the decomposition of acetate results on liberation of CO, CO2, H2O (complete combustion), ketene (dehydration) and small amounts of acetone (acetate coupling) detected by TPD. On reduced ceria, acetate decomposition liberates H2 and small amounts of acetaldehyde and acetylene (dehydration and dehydrogenation), but a substantial amount of C is left on the surface. Decomposition products yield could be varied by changing the reduction degree of the surface thus allowing the possibility of tuning catalyst selectivity.