Communications Project

Document Type:Dissertation
Name:Todd P. St. Clair
Title:Characterization and Reactivity of Mo2C
Degree:Doctor of Philosophy
Department:Chemical Engineering
Committee Chair: David F. Cox
Committee Members:S. Ted Oyama, Co-chair
John G. Dillard
Brian E. Hanson
Michael F. Hochella
Keywords:single crystal molybdenum carbide, thiophene desulfurization
Date of defense:June 4, 1998
Availability:Release the entire work for Virginia Tech access only.
After one year release worldwide only with written permission of the student and the advisory committee chair.


Two types of Mo2C have been investigated: polycrystalline beta-Mo2C and single crystal alpha-Mo2C. The beta-Mo2C material was synthesized via a temperature-programmed method, and then characterized using x-ray diffraction (XRD), x-ray photoelectron spectroscopy (XPS), CO chemisorption, and N2 physisorption. The catalytic activity of the beta-Mo2C was tested for cumene hydrogenation under high pressure conditions, and the effect of sulfur and oxygen poisons on cumene hydrogenation was also investigated. As a complement to the work done on polycrystalline beta-Mo2C, UHV studies of single crystal alpha-Mo2C were undertaken to provide fundamental information about a well-characterized Mo2C surface. The (0001) surface of alpha-Mo2C was investigated using XPS and low energy electron diffraction (LEED). It was found that an ion-bombarded surface could be prepared as either Mo-terminated or C-terminated by choosing either low annealing temperatures (~1000 K) or high annealing temperatures (~1500 K), respectively. CO and O2 adsorption was also studied on alpha-Mo2C (0001) using thermal desorption spectroscopy (TDS), XPS, Auger electron spectroscopy (AES), and LEED. Finally, thiophene adsorption was investigated on alpha-Mo2C (0001).

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