Imparting Nobility to Base-Metal Hydrides for CO2 Hydrogenation

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In this project funded by the Chemical Catalysis program of the Chemistry Division, Professor Connie Lu of the University of Minnesota, Twin Cities is developing molecular catalysts to transform carbon dioxide into useful chemicals and/or liquid fuels. Sustainable processes for producing commodity chemicals and for storing energy are increasingly relevant to a secure energy future. Because of its abundance and ease of handling, carbon dioxide has the potential to serve as a renewable single-carbon feedstock for the chemical industry. Professor Lu is using catalysts featuring earth-abundant metals addressing a broader challenge in catalysis: to replace traditional catalytic metals with cheaper, available alternatives. Besides building experience in catalysis research, graduate students are trained to collaborate across traditional disciplinary boundaries and gain workforce-related training abroad. Outreach activities focus on teaching catalysis and energy to K-12 students through experiments and/or demonstrations.The bimetallic catalysts being developed for carbon dioxide hydrogenation feature base metals (Ni, Co, and Fe) supported by Lewis acidic Group 13 ions. The premise of the proposed work is that the Lewis acidic center will be a powerful lever to tune the reactivity at the base metal. Extensive effort is dedicated to mechanistic investigations using a combination of synthetic, spectroscopic, and theoretical approaches to evaluate how catalytic activity depend on the supporting ion. Key intermediates are isolated and characterized, including novel anionic metal hydrides, whose negative charges result in high reactivity. Hydride transfer to other substrates with polar C=O substrates is also investigated. The work builds knowledge about how to leverage Lewis acid supports, so to endow higher selectivity and/or efficiency to base-metal active sites. Assessing the impact of the Lewis acid support on catalytic efficiency and selectivity leads to catalyst descriptions, both experimental and theoretical in nature, which may be transferrable to other catalyst systems.