Role of Hydroxyls on Breaking Ether C-O Bonds Adsorbed on CeOx(111) Model Catalysts

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

Milwaukee, WI

Conferencia; 70th Physical Electronics Conference; 2010

University of Wisconsin - Milwaukee

Poster #20 The study of adsorption and reactivity of oxygenated molecules on model oxide catalysts is of great interest to gain a better understanding of the mechanism of industrial reactions. Cerium oxide is commonly used in three-way auto exhaust and WGS catalysts. From the surface science point of view, previous studies of alcohols, ketones and aldehydes adsorbed on the surface of cerium oxide model catalysts had shown a variety of pathways concerning the decomposition and reactivity of these molecules. Ethers adsorbed on fully oxidized CeO2(111) and partially reduced CeOx(111) at UHV conditions did not show reactivity towards decomposition. If the catalyst surface is pre-covered by hydroxyls, by adsorbing water on the reduced CeOx(111) surface, then the ether molecules promptly react by breaking the C-O bond presenting a very interesting chemistry. By means of Reflection Absorption Infrared Spectroscopy (RAIRS) at UHV conditions, we could detect alkoxydes and possibly carboxylates as adsorbed intermediates for the reaction. In real catalysts at real conditions the ether molecules are known to react on cerium oxide catalysts giving a variety of products depending on the reaction conditions. Our experimental design is intended to find the conditions where UHV experiments could mimic the real catalytic processes and from these results explain the reaction pathway from the atomistic level. From these preliminary results, possible explanations for the role of hydroxyls in helping break the C-O bond of ether molecules will be given.