Chemistry Department Colloquium

It is well known that bimetallic catalysts often show novel properties that are not present on either of the parent metal surfaces. However, it is difficult to know a priori how the chemical properties of a particular bimetallic surface will be modified relative to the parent metals. In the past few years our research group has investigated the novel catalytic properties of various bimetallic systems, using a combination of Density Functional Theory (DFT) modeling, surface science studies on single crystal surfaces, and reactor evaluations of supported bimetallic catalysts [1-3].
In the current presentation we will use several probe reactions to demonstrate the unique chemical and catalytic properties of bimetallic surfaces. We will use the hydrogenation of alkenes, which is a reaction that requires relatively weak bonding of atomic hydrogen and alkenes, to demonstrate the utilization of bimetallic surfaces to enhance the hydrogenation activity; we will also use the selective hydrogenation of the C=O bond in unsaturated aldehydes to illustrate the possibility of controlling the selectivity with bimetallic surfaces [4]. Next, we will present results for controlling the activity and selectivity of bimetallic surfaces for the reforming of oxygenates (alcohols and glycols) and dehydrogenation of ammonia [5], which represent reactions that require relatively strong bonding of adsorbatess. Finally, we will present thermodynamic stability and kinetic measurements to enhance the stability of bimetallic catalysts by replacing one of the metal components with carbides [6,7]. Overall, these results demonstrate the possibility of selecting catalytic materials with desirable activity, selectivity and stability based on combined DFT predictions, surface science verifications and reactor evaluations.

[1] Hwu et al. J. Am. Chem. Soc. 124 (2002) 702
[2] Kitchin et al. Phys. Rev. Lett. 93 (2004) 156801
[3] Chen et al. Surf. Sci. Reports, 63 (2008) 201
[4] Murillo