CAREER: Nanoparticle Non-Noble Metal Intermetallic Compounds as Tunable Catalysts for Selective Hydrogenation Reactions

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The project will investigate new, low-cost materials for catalyzing important chemical reactions associated with the refining of petroleum and bio-based materials to produce fuels and a wide range of chemical products. In addition, the project will explore the potential for improving the effectiveness of the catalytic materials by synthesizing them as nanoparticles rather than traditional micron-sized particles. The new materials can be formed through combinations of many different elements, and the study will also develop methods for predicting the best combinations of elements for specific chemical reactions, thereby streamlining the catalyst discovery process and promoting U.S. competitiveness in the fuels and chemicals manufacturing sectors. The project will be linked to educational and outreach efforts that will train the next generation of engineers, and increase public awareness of new energy-efficient technologies such as fuel cells and batteries.Preliminary efforts in the investigator's laboratory have established a working understanding of how supported nanoparticle intermetallic compounds (IMCs) may be synthesized with well-defined bulk and surface compositions. The project will utilize those findings to enable a systematic study of IMC surface chemistry as a function of constituent elements in the selective hydrogenation of unsaturated aldehyde and nitro compounds. Experimental and computational methods will be used to examine the selectivity of C=C, C=O, and N-O activation, dissociation, and hydrogenation as a function of IMC bulk and surface composition and electronic structure information. Synthesis of oxide-supported non-noble metal nanoparticle IMCs will focus on developing clear understanding of the physical phenomena that dictate their bulk and surface composition as a function of element selection, oxide choice, and preparation environment. Formation of the bulk crystal structure of the nanoparticles will be investigated by ex- and in-situ x-ray diffraction and neutron scattering. Complementary high-resolution energy-dispersive x-ray spectroscopy will verify bulk composition and quantify elements not incorporated into the IMC nanoparticles. Surface composition of the IMCs will be analyzed using low energy ion scattering. Diffusion of constituent elements, particle growth, and bulk crystal structure will be analyzed as a function of synthesis variables to produce a complete picture of how well-defined nanoparticle IMCs may be produced. Results of these studies will allow for a general procedure to be developed for the synthesis, characterization, reactivity evaluation, and stability analysis of the IMC catalysts. Beyond the targeted reactions, the project will enable atomic- and electronic-level understanding of how nanoparticle IMC catalysis can be controlled and widely utilized in chemical transformations important to the field of heterogeneous catalysis. The educational component of the proposed program will serve to develop a surface and materials chemistry education program at the University of Tennessee, Knoxville. In addition, a YouTube video series, focused on materials, surface, and catalytic science, will be developed in a format accessible to the general population to promote a greater understanding of the impact these sciences have on everyday life.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.