Adsorption and Reaction of Acetone over CeOx(111) Thin Films

This study reports the interaction of acetone (CH 3 COCH 3 ), the simplest ketone, with well ordered CeO 2 (111) thin film surfaces. The fully oxidized CeO 2 (111) surface shows a weak interaction with acetone with the sole desorption product (TPD) being acetone at 210 K. The chemisorbed molecule binds to the surface as the η 1 -acetone species rather than through a bridge-bonded dioxy-configuration. Exposure of a CeO 2 (111) surface to acetone at 600K removes oxygen as CO and results in the conversion of Ce 4+ to Ce 3+ . Acetone chemisorbs strongly on reduced CeO 2− x (111) with molecular acetone desorbing near 500 K. Decomposition also occurs with H 2 desorbing between 450 and 600 K and C reacting with O in the ceria to desorb above 650 K. A stable species exists from 200 to 500 K on the reduced surface that has three unique types of C. High resolution C 1s XPS spectra indicate these are Ce−CH 2, C− C H 3 and C−O species. C k-edge NEXAFS indicates the presence of C═C and C═O bonds. It is postulated that the intermediate is a carbanion bonded through both O and C atoms to Ce cations.