GOALI/FRG: Structural Properties of Alumina and Adsorbed Metal Particles

Vanderbilt University, Nashville TN

Investigators

Abstract

The focus of the proposal is to pursue fundamental understanding of structural transformations in materials that occur in applications and device methods to control them so that they can be either averted or enhanced, as needed by industry. The specific problem of interest is the stabilization of g-alumina that is widely used as a catalyst support and as a catalyst. At high temperatures, g-alumina, which is porous, converts to a-alumina, which is not porous, and catalytic activity stops. Empirically, it has been found that the addition of 3.5-5% lanthanum stabilizes g-alumina. In a laboratory process developed by one of the PIs, it has been found that stabilization can be achieved with only 0.3-0.5% La, but the process is not scalable for manufacturing (La is very expensive). The proposed research will use a combination of atomic-resolution Z-contrast microscopy and electron-energy-loss spectroscopy and first-principles theoretical modeling to understand the atomic-scale processes that underlie the phase transformation and the stabilization with different impurities. A second problem will be the interaction of catalytic particles with the alumina substrate in catalytic systems. The PIs at two universities, a national lab, and an industrial lab have prior expertise and collaborative synergy on similar projects in the past and also propose to develop a parallel educational program. %%% The proposed research will seek to understand the atomic-scale processes that underlie a phenomenon that has proved to be quite costly for industry: the material known as g-alumina is porous and is used as a substrate in catalytic systems. At high temperatures, it undergoes a transformation to a different phase known as a-alumina (different atomic arrangements in the crystal), which is not porous. Catalytic activity stops. Addition of 3-5% of the rather expensive element lanthanum stabilizes g-alumina. One of the PI's developed an alternative process that produces stable g-alumina with only 0.3-0.5% La, but the process cannot be scaled for manufacturing. The PIs have an assembly of unique experimental and theoretical tools and have demonstrated synergistic collaboration in the past. They will be able to determine the atomic scale processes that are responsible for the transformation and the stabilization by impurities and develop alternative approaches with either La or other impurities that will be efficient and cost-effective. In addition, they propose to study related interactions between catalytic metal particles on alumina substrates. Finally, they propose an educational program that will enable students to participate in research done at a national lab and an industrial lab.