Structure dependence in acetaldehyde reactions on CeO2 studied using monolithic and nanoscopic single crystal surfaces

MANN, AMANDA KAY PETERSON; CALAZA, FLORENCIA C.; ALBRECHT, PETER; LI, MEIJUN; WU, ZILI; XU, YE; MULLINS, DAVID R.; OVERBURY, STEVEN H.

Indianapolis

Conferencia; 246th ACS National Meeting; 2013

AMERICAN CHEMICAL SOCIETY

We have utilized monolithic CeO2 surfaces with two different orientations and shaped particles of CeO2 with three different morphologies to probe the effect of surface structure upon the adsorption and redox pathways for ethanol, acetaldehyde and acetic acid. Here we focus on acetaldehyde adsorption and reaction. Monolithic surface studies demonstrate different reactivities on the (111) compared to the (100) surfaces. 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. These were used to perform studies of the surface species present during adsorption and reaction and compared with reaction studies that elucidate how these shaped catalysts perform under practical catalytic conditions. Selectivity for oxidative dehydrogenation of ethanol has previously been found to vary between the different shapes as are the tendency for enolization and coupling reactions of acetaldehyde to form crotonaldehyde. Differences in reaction behavior are related to the geometry of local sites, the strength of bonding and the ease of vacancy formation which enables the surface to contribute oxygen to surface intermediates.