Collaborative Research: Correlating Molecular Structure and Activity in Boron-containing ODH Catalysts

Iowa State University, Ames IA

Investigators

Abstract

As the world population grows, the demand for consumer goods, which are made from building-block chemicals such as ethylene and propylene, increases. The project focuses on discovery of energy-efficient catalysts for the production of these chemical building-blocks from natural gas with minimal generation of undesired by-products such as carbon dioxide. Preliminary studies by the investigators have shown exceptional promise of boron-containing catalysts, but deeper, atomic-level understanding is needed to further improve the catalyst performance and durability. The project will utilize a combination of new catalyst synthesis protocols, state-of-the-art solid-state nuclear magnetic resonance imaging, and computational methods to obtain the needed atomic-level understanding, and use that insight to design improved catalysts. The research will support U.S. clean-energy security through its potential for the efficient conversion of our nation's vast shale gas resources to value-added fuels and chemicals. Oxidative Dehydrogenation (ODH) of light alkanes is a promising alternative for the production of important chemical building blocks. However, despite decades of research, a highly selective catalyst has remained elusive, as over-oxidation is a facile and thermodynamically favored process. Recent studies by the lead investigator's group has demonstrated that boron-containing catalysts (hBN, BNNT, WB, among others) are highly selective catalysts for the ODH of light alkanes. For propane ODH, propylene selectivity as high as 80% can be obtained up to 20% conversion, compared to 60% propylene selectivity at 10% propane conversion for the state-of-the-art vanadium oxide-based catalyst. Given the recent discovery of this class of materials as ODH catalysts, there are many fundamental questions that need to be answered regarding the active sites and their formation. Controlled synthesis, state-of-the-art solid-state NMR (SSNMR) spectroscopy, and computational modelling will be utilized to gain insights into the catalytically active site(s) and build up a structure-performance relationship for boron-containing ODH catalysts. The work will contribute to a molecular-level understanding of a complex problem that is of industrial importance. Our multidisciplinary approach comprised of synthesis, SSNMR characterization, catalytic testing, and computational modelling will train the participating students to use information from a variety of fields to develop a detailed picture of a complex system. Additionally, the collaborative nature of this work will help the students grow as productive members of a research team. Beyond the targeted reactions, the study will be of value to the broader catalysis community because of the generalized catalytic insights and the methods developed for characterization of heterogeneous materials. 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.