Faculty

Professor Emeritus M. Albert Vannice | Research

The creation and utilization of metal-support interactions (MSI) have allowed us to develop catalysts with higher specific activities in selected probe reactions. The selective activation of specific functional groups, such as carbonyl bonds, is being examined in reactions like the hydrogenation of benzaldehyde, acetic acid and citral. A better understanding of this control to activate groups is expected to have an impact on specialty chemical production and environmental concerns. To study these catalysts we are developing and applying methods such as selective chemisorption, in situ IR spectroscopy under reaction conditions, differential scanning calorimetry, solid-state NMR, and surface science techniques. A unique high pressure reactor system has been built to allow us to study the influence of MSI in liquid - phase reactions.

Carbon-supported metal catalysts constitute an important portion of our program because they offer so much potential but are seldom studied. We have prepared both pure-metal and mixed-metal clusters. To better understand the chemistry associated with these clusters, we have utilized Mossbauer spectroscopy, STEM/EDS (Electron Dispersion Spectroscopy), magnetic susceptibility, solid-state NMR, and DRIFTS (Diffuse Reflectance Fourier Transform IR Spectroscopy). The last method has recently been developed in our lab for opaque materials, and it represents a significant advance in the characterization of carbon surfaces as well as carbon-supported metals by IR spectroscopy. We can now also conduct subambient DRIFTS investigations.

We have a major effort in environmental catalysis with a particular emphasis on decreasing NOx emissions. This involves studies of both NOx decomposition and NOx reduction by methane and other organics over oxide catalysts, especially rare earth oxides such as La₂O₃. The investigations employ kinetic analysis, in situ DRIFTS, TPD and TPR, ESR, and chemisorption techniques. These studies will impact both stationary and mobile NOx sources, with lean-burn engines included in the latter group.

In our continuing effort to use new methods to better characterize these supported metal systems, we have developed a microwave Hall effect technique to measure the electrical properties of powders and of small metal crystallites dispersed on oxide powder supports. These measurements when combined with those of electrical conductivity allow calculation of the number of electron carriers, which should help answer important questions now being asked about metal crystallite size effects and metal-support interactions.

In summary, we strive to apply new techniques to characterize catalysts, which we have found to possess unique capabilities, in an effort to better understand and improve them.

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