Structure dependences in reactions of C2 oxygenates on CeO2 nanoshapes

OVERBURY, STEVEN H.; WU, ZILI; LI, MEIJUN; CALAZA, FLORENCIA C.

New Orleans

Conferencia; 245th ACS National Meeting; 2013

AMERICAN CHEMICAL SOCIETY

We have utilized shaped particles of CeO2 to probe the effect of surface structure upon the adsorption and redox pathways for ethanol, acetaldehyde and acetic acid. Nanosized octahedra, cubes and rods of CeO2 have been synthesized and used to represent surfaces that terminate in (111), (100) and a mix of defective (110) and (100) planes, respectively. We have used DRIFTS and QMS based product analysis to examine reaction products and surface species under temperature programmed and steady state conditions to explore how structure of the CeO2 particles alters the surface speciation and reaction pathways. Selectivity for oxidative dehydrogenation of ethanol are found to vary between the different shapes as are the tendency for enolization and coupling reactions of acetaldehyde to form crotonaldehyde. The defective rods are most active for promoting oxidation reactions becasue of their low vacancy formation energy enables them to contribute oxygen to surface species, while octahedra with higher vacancy formation energy favor more selective reactions.