Catalytic Reactivity at the Metal-Solution Interface

University Of Virginia Main Campus, Charlottesville VA

Investigators

Abstract

ABSTRACT #1157829 Davis, Robert J. Technical Impacts: Supported metal catalysts composed of metal nanoparticles on alumina and silica supports have been optimized for the upgrading of fossil fuels as well as the production of petrochemicals. The recent transition of some chemical processes to utilize biorenewable feedstocks requires new catalysts to be active in liquid water, a reaction medium that is not commonly found in the fossil fuel based industries. Water is a very low cost, highly-polar, environmentally benign solvent that has great potential as a reaction medium for catalytic transformations of biomass. Indeed, many molecules derived from biomass are highly-oxygenated and quite polar compared to hydrocarbons and are likely to decompose rather than vaporize, thus eliminating the traditional conversion options. The oxide supports are not stable in the aqueous reaction medium. Therefore, new catalysts for aqueous-phase catalytic processing of carbohydrate-derived feedstocks must be a priority interest in the chemical community. The fundamental catalysis chemistry in these aqueous systems must be understood to make best use of the renewable feedstocks under consideration. Professor Robert J. Davis of the University of Virginia has begun these investigations, most recently observing the mechanisms of glycerol reactivity at catalyst surfaces. This new project explores the nature of the catalytic active site and probes the reactivity of adsorbed intermediates on two metal catalyst systems that are highly relevant to the catalytic transformation of biorenewable molecules in liquid water. The oxidation of polyols to diacids on Au catalysts and the hydrogenolysis of polyols to diols on bimetallic Pt-Re catalysts will be probed by in-situ attenuated total reflectance FTIR spectroscopy of model nanoparticle and thin film catalysts and compared to the performance of supported metal catalysts in high pressure batch and flow reactors. Preliminary research has revealed unique reactivity of both Au and Pt-Re catalyst systems in liquid water but the fundamental mechanistic principles by which these systems function are still unknown. This study will elucidate the key features of the metal-water interface which may then be generalized to other reactions of interest in aqueous systems. Davis intends to combine concepts of acid/base chemistry together with catalysis by metals to explain the catalytic reactions that occur in liquid water and to elucidate design principles that can be utilized for the synthesis of next generation catalysts. Education and Outreach Impacts: A new outreach effort will involve participation of the principal investigator in a recently-formed organization created at the University of Virginia called NExT (for Nano and Emerging Technologies) and a new non-profit organization called NextTech, which broadens the impact of NExT to other universities and forms junior chapters at high schools across the country. NExT and NextTech engage local K-12 students throughout the year and include mentoring science fair projects,guest seminars/demos, and co-sponsored events. The PI will interact with a local high school that has recently added a new program called the Math Engineering and Science Academy, that combines teaching in math and science to involve real world problem solving, collaboration and inquiry-based learning.