Elucidation of active sites for the reaction of ethanol on TiO2/Au(111)

Author

David T. Boyle, James Madison UniversityFollow

Creative Commons License

This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 4.0 License.

Date of Graduation

Spring 2017

Document Type

Thesis

Degree Name

Bachelor of Science (BS)

Department

Department of Chemistry and Biochemistry

Advisor(s)

Ashleigh E. Baber

Thomas C. Devore

Brycelyn M. Boardman

Abstract

Obtaining a molecular-level understanding of the reaction of alcohols with heterogeneous model catalysts is critical for improving industrial catalytic processes, such as the production of H₂ from alcohols. Gold has been shown to be an excellent oxidation catalyst once oxygen is added to it. The use of reducible oxides provides a source of oxygen on Au(111) for the reaction of ethanol, which is easily regenerated in the presence of an oxygen background. In this work, ethanol operates as a probe molecule to investigate the role of Au(111), TiO₂ nanoparticles, and TiO₂/Auinterfacial surface sites on the catalytic properties of TiO₂/Au(111). Ultrahigh vacuum temperature programmed desorption (TPD) studies with ethanol/Au(111) elucidate previously unreported adsorption sites for ethanol. Ethanol molecularly adsorbs to Au terrace sites, step edges, and undercoordinated kink sites with adsorption energies of -51.7, -55.8, and -65.1 kJ/mol, respectively. A TPD coverage study of ethanol on TiO₂/Au(111) indicates ethanol undergoes dissociative adsorption to form H*(a) and CH₃CH₂O*(a) on the inverse model catalyst surface. The desorption temperature of low coverages of ethanol from TiO₂/Au(111) (T_des= ~235 K) is at an intermediate temperature between the desorption temperatures from bulk Au(111) and TiO₂(110), indicating both Au and TiO₂ play a role in the adsorption of ethanol. Both low-temperature adsorption and high-temperature reactions are studied and indicate that ethanol-derived products—such as acetaldehyde and ethylene—desorb from TiO₂/Au(111) at ~500 K.

Recommended Citation

Boyle, David T., "Elucidation of active sites for the reaction of ethanol on TiO2/Au(111)" (2017). Senior Honors Projects, 2010-2019. 351.
https://commons.lib.jmu.edu/honors201019/351