Structure-Property Relationship in Transition Metal Carbides
The carbides of early transition metals (Groups IVB-VIB) are characterized by many unique and intriguing catalytic properties. It is now well established that, compared to their parent metals, TMCs often demonstrate catalytic advantages in activity, selectivity, and resistance to poisoning. It has also been demonstrated that the catalytic performances of TMC are approaching or surpassing those of the more expensive Pt-Group metals (Pt, Pd, Ir, Rh and Ru), particularly in catalytic reactions involving the transformation of C-H bonds of hydrocarbons, such as in dehydrogenation, hydrogenation, hydrogenolysis, and isomerization reactions.
We have performed a series of surface science and catalytic investigations of the unique catalytic properties of TMCs. We have adopted three parallel experimental approaches: (1) to develop experimental procedures for the preparation of thin TMC films with desired electronic and structural properties; (2) to utilize a battery of surface science techniques to determine the correlation between electronic, structural and catalytic properties; and (3) to correlate the surface reactivities of the model TMC thin films to the catalytic properties of powder catalysts. Currently we are also investigating the catalytic properties of TMC nanoparticles. The combined synthesis, characterization and reactivity studies should help us determine the following two important properties of supported TMC: (a) what are the novel electronic and/or structural properties of the TMC nanoparticles and (b) at what particle dimension do the electronic and structural properties of TMC nanoparticles approach those of bulk TMC materials.
Associated Graduate Students and Information on Specific Thesis Topics
Alan Lee Stottlemyer (Graduate Student)
Erich Weigert (Graduate Student)
Recent Publications in This Area
H.H. Hwu and J.G. Chen, “Reactions of Methanol and Water on Carbide and Oxycarbide- Modified Mo(110)”, Surface Science 536 (2003) 75-87.
M. Zhang, H.H. Hwu, M.T. Buelow, J.G. Chen, T.H. Ballinger, P.J. Andersen and D.R. Mullins, “Decomposition Pathways of NO on Clean and Carbide-Modified W(111) Surfaces”, Surface Science, 522 (2003) 112-122.
H.H. Hwu, B. Fruhberger and J.G. Chen, “Different Modification Effects of Carbidic and Graphitic Carbon on Ni Surfaces”, Journal of Catalysis, in press (2003).
H.H. Hwu and J.G. Chen, “Substrate-Dependent Reaction Pathways of Ethylene on Clean and Carbide-Modified W(110) and W(111)”, Journal of Physical Chemistry B, in press (2003).