Collaborative Research: SusChEM: Manipulation of Reaction Selectivity in the electrochemical environment for biomass-to-chemicals conversions

Manipulation of reaction selectivity in the electrochemical environment for biomass-to-chemicals conversions Fuels and chemicals derived from plant matter (biomass) are a promising means to sustainably meet demands for energy and commodity products. Biomass is a "carbon neutral" feedstock because it grows by incorporating CO2 from the atmosphere while only consuming solar energy. This project is finding new and efficient outlets to generate useful chemicals from components of biomass that are currently difficult to process. While most biomass conversions are presently performed using catalysts and energy supplied by heat, this work is exploiting unique aspects of electricity-driven catalytic reactions in order to achieve synthesis of useful chemicals at low temperatures and pressures. The electricity required for these processes may, in turn, be derived from renewable sources such as wind and solar. A fundamental approach is being taken in which experimental techniques that probe the nature of the catalytic reactions are combined with computer simulations to build a comprehensive picture of the factors that govern reaction selectivity and to design more efficient processes. Insights from this work have broader application in extending the scope of green chemistry. This research is also being used to promote science education by involving undergraduate student researchers for summer internships, and the PI's are additionally developing a series of interactive educational modules related to understanding the physical processes governing electro-catalytic reactions. This project is investigating electrochemical control over selectivity in the conversion of biomass-derived feedstocks to desired chemical targets. Electrochemical conversions offer advantages in sustainable processing since they generally operate at low temperatures and utilize aqueous feedstocks directly. Using selective oxidation of furfural and 5-hydroxymethyl furfural over Pt electrodes as probe systems, this work focuses on determining the different mechanisms by which selectivity can be manipulated through control over electrode potential and composition. Mechanisms being explored include differentiation of charge-transfer reactions relative to neutral atom transfer reactions, variation in surface coverage of oxygen and organic species, and the role of promoters with specific reactivity or geometry. Three complementary research approaches are being integrated to characterize these effects. Measurement of electrochemical kinetics on metal catalysts is combined with in-situ spectroscopy to identify reaction pathways; surface science experiments are used on a model Pt(111) surface to study oxidation elementary steps in detail; and finally, density functional theory calculations are used to investigate the same surface chemistry, including simulation of electric potential effects and the water-metal interface. The three research thrusts provide complementary information and enrich the depth of understanding of the electrochemical environment. Insights from this work have broader application in extending the scope of green chemistry and electrochemical synthetic routes. This research is also being used to promote science education by involving undergraduate student researchers for summer internships, and the PI's are additionally developing a series of interactive educational modules related to understanding the physical processes governing electro-catalytic reactions.