AVS 63rd International Symposium & Exhibition
    Surface Science Monday Sessions
       Session SS+AS+HC-MoA

Paper SS+AS+HC-MoA5
Structure and Ethanol Reactivity of Ti-modified CeOx(111) Mixed Oxide Surfaces

Monday, November 7, 2016, 3:00 pm, Room 104E

Session: Metals, Alloys, and Oxides: Reactivity and Catalysis
Presenter: Jing Zhou, University of Wyoming
Authors: E.W. Peterson, University of Wyoming
J. Zhou, University of Wyoming
Correspondent: Click to Email
Ceria has been widely studied as an oxidation-reduction catalyst due to its unique redox properties and oxygen storage capacity. There has been an interest to incorporate additional metal dopants such as Ti into ceria to potentially enhance the thermal stability as well as improve the redox properties for practical applications in catalysis. This paper focuses on the fundamental mechanistic understanding of the effect of Ti dopant on the structure and reactivity of ceria using scanning tunneling microscopy, X-ray photoelectron spectroscopy, infrared spectroscopy and temperature programmed desorption techniques. In the study, submonolayer coverage of Ti was deposited on well-ordered CeOx(111) (1.5<x<2) thin films at room temperature. XPS studies show that Ti is oxidized to Ti4+ at the cost of Ce4+ reduction. Observation of CO IR band at 2173 cm-1 further confirms the presence of titania on the ceria surface. At 300 K, small atomic-like features of Ti-O-Ce linkages are present on ceria, which can coalesce into chain structures after heating to 700 K. Upon ethanol adsorption at 300 K, ethoxy was the surface intermediate observed on both oxidized and partially reduced ceria surface. With heating, it can go through the dehydration or dehydrogenation process to form acetaldehyde, ethylene, water and hydrogen products. Our studies have demonstrated that addition of Ti in ceria can affect the dehydration and dehydrogenation selectivity. Furthermore, the nature of ceria supports associated with oxygen vacancies and Ti dopants can have a promotional effect in the stability of deposited metal nanoparticles, such as Ni, and the chemical behavior toward the adsorption and reaction of ethanol. The research is sponsored by the National Science Foundation Career Grant (Award Number: CHE1151846) and the Wyoming NASA EPSCoR (NASA Grant: NNX13AB13A).