(675b) Insights into the Electrochemical Conversion of Biomass Derivatives to Fuels and Chemicals

A number of biomass processing routes yield aqueous solutions of highly-functionalized small molecules. The removal of oxygen-rich functional groups (hydroxyl, carboxyl, ketone, aldehyde) and unsaturated bonds from these species is crucial for upgrading to fuels. Additional types of transformations (partial reductions or oxidations) are also important enabling technologies, as the displacement of fossil fuels will entail a viable biomass-derived chemicals industry.

Electrochemical upgrading routes pose several potential advantages for processing aqueous bio-derived feedstocks. Rearrangements of hydrogen and oxygen are accessible at ambient temperatures and pressures, often with novel selectivity profiles, as elementary reaction steps that are mediated by electron transfer can be accelerated relative to neutral atom-transfer steps. Deoxygenated products can often be separated naturally, and utilizing electric potential as a driving force can be advantageous when large sensible heats associated with solvents hamper the efficiency of using heat.

Our work has focused on electrochemical conversion of two groups of biomass-derived intermediates. We will show recent progress on (i) partial oxidation of furans (mainly derived from hydrolysis) to commodity chemicals and (ii) reduction of C₄-C₆ carboxylic acids (derived by a novel fermentation process) to light alkanes and alcohols. We have performed a number of kinetic studies, including isotopic labeling with differential electrochemical mass spectrometry (DEMS), as well as in-situ spectroscopic (ATR-FTIR) characterization of these chemistries. Reactivity trends with respect to conditions (pH, potential, electrolyte ion and solvent) as well as over a series of electrocatalytic materials will be discussed. The work supports a broader goal to establish principles for selective tuning of functional group transformations in the electrochemical environment.