| AVS 57th International Symposium & Exhibition | |
| Surface Science | Thursday Sessions |
| Session SS-ThM |
| Session: | Adsorption and Reactivity on Oxide Surfaces |
| Presenter: | T.-L. Chen, Oak Ridge National Laboratory |
| Authors: | T.-L. Chen, Oak Ridge National Laboratory F.C. Calaza, Oak Ridge National Laboratory S.H. Overbury, Oak Ridge National Laboratory D.R. Mullins, Oak Ridge National Laboratory |
| Correspondent: | Click to Email |
Hydrogen production from the reforming of oxygenated hydrocarbons is highly dependent on the heterogeneous reactions provided by its catalysts. Cerium oxide supported metal catalysts can offer a means of reducing precious metal loading and achieving higher selectivity. Thus studying the direct contribution from the metal oxide surface to the decomposition of the molecules can give insight into the catalytic reforming process.
In light of our previous characterization on C1-C3 oxygenate reactions on well-defined cerium oxide thin films, we further examine ethylene glycol as a model system for bio-mass derived hydrocarbons. As the simplest diol, ethylene glycol has two symmetric hydroxyl groups which are available to interact with the surface. The absorbates can bond to the surface through either one or both of these oxygens, which may lead to a different decomposition pathways.
On the surface of the fully oxidized ceria ethylene glycol appears to initially bond to the surface through only one of the C-O groups. As the temperature is increased both ends interact with the surface and one C-O group is converted into a carboxylate group (COO). The primary reaction products are acetaldehyde, ethylene, acetylene, water and H2. CO desorption was also observed indicating some of the oxygenates experienced C-C bond breaking. On a reduced surface one end of the molecules undergoes C-O cleavage resulting in a C-Ce bond rather than an additional C-O bond. The surface intermediate is a carbanion, similar to what was observed for acetaldehyde. More acetylene is observed from a reduced surface.
The dependence of the reaction pathways on the coverage of ethylene glycol was also examined on the oxidized and reduced surfaces. At larger coverage, the formation of carboxylates or carbanions is hindered which suggests that the formation of these species may be sterically limited.
Research sponsored by the Division of Chemical Sciences, Geosciences, and Biosciences, Office of Basic Energy Sciences, US Department of Energy, under contract DE-AC05-00OR22725 with Oak Ridge National Laboratory, managed and operated by UT-Battelle, LLC. Use of the National Synchrotron Light Source, Brookhaven National Laboratory, was supported by the US Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-98CH10886.