Jeff Miller joined the Chemical Engineering faculty at Purdue University in 2015. His research interests at include development and of new catalysts for conversion of abundant shale gas hydrocarbons to fuels and chemicals. His research group has also interested in synchrotron characterizations of these catalysts under reaction conditions. Prior to joining Purdue, he was the Heterogeneous Catalysis Group Leader at Argonne National Laboratory’s Chemical Sciences and Engineering Division. His group developed new catalytic materials and fundamental understandings for energy production. Prior to joining Argonne, Jeff worked for the Amoco Oil Company (now BP) for more than 27 years.
Metal nano-particle alkane dehydrogenation catalysts utilize Pt and are generally promoted by Sn, Zn, Ga or In. While Pt bimetallic nano-particles are highly selective, their exact structure is not generally known, especially in very small nano-particles. Recently, it was shown that intermetallic alloys were are present on PtIn dehydrogenation catalysts and other bimetallic compositions. The increased olefin selectivity was suggested to be due to isolation of the active Pt atoms. Changes in the turnover rate (TOR) and activation energy also suggested electronic effects. In this study, Zn addition to Pt on SiO2 leads to the formation of a Pt1Zn1 intermetallic alloy structure including at the active surface. The higher TOR and activation energy also suggests and electronic changes of Pt. Measurement of the energy of filled and unfilled d-orbitals in Pt and Pt1Zn1 using Resonant Inelastic X-ray scattering confirms a significant electronic effect of the energy of the d-orbitals, which is confirmed by DFT calculations. The latter are compared to traditional density of state calculations and provide more detail on the electronic properties of bimetallic catalysts.
The presentation will describe catalytic compositions, which are highly selective and stable for alkane dehydrogenation, methods for atomic level characterization of the structure and changes in the electronic properties of these catalysts. These methods and understandings are generally applicable to many catalytic materials and processes.