(155d) Electrocatalytic Processing of Renewable Biomass-Compounds to Generation of Electricity, Chemicals and Fuels

Biomass is abundant, inexpensive and renewable, therefore, it is expected to play a significant role in our future energy landscape. The U.S. DOE has identified some platform compounds (or building blocks, i.e. glycerol, levulinlic acid, etc.) that can be mass-derived from biomass, currently the chief research need is to develop cost-effective, green and sustainable approaches to utilize these biorenewable compounds. I will present our recent efforts on exploration of aqueous phase electrocatalytic processing of the renewable biomass platform compounds to production of electricity, valuable chemicals and biofuels. We discovered that electrocatalytic oxidation of biorenewable polyols to valuable products with a tuneable degree of oxidation can be achieved by varying electrode potential. The degree of glycerol oxidation over Au nanoparticles was tuned with anode potential to produce tartronate (oxidizing two primary -OH groups, ≥ 0.35 V), mesoxalate (oxidizing three -OH groups, ≥ 0.45 V), or glycolate (breaking C-C bond, ≥ 0.9 V), and the mechanism of potential-controlled glycerol electro-oxidation has been proposed. This may open a new strategy for the targeted transformation of biomass compounds with poly or multi- functional groups into valuable chemicals. We further demonstrated high power density anion exchange membrane fuel cell with crude glycerol fuel using carbon supported PtCo dealloyed catalyst. We also explored electrocatalytic processes to store renewable electricity in biofuels, and have demonstrated electrocatalytic reduction of levulinic acid to higher energy-density biofuel intermediates: valeric acid (VA) or γ-valerolactone (gVL) on non-precious Pb electrode with high yield and faradaic efficiency in a single electrolysis flow cell reactor. The applied potential and electrolyte pH were found to control the reduction products. It is interesting that formic acid (coproduced in cellulose hydrolysis stream) can improve the rate of electro-reduction of LA to VA. Our work shows promise for direct electrocatalytic processing of crude biorefinery streams to electrical energy and biofuels/intermediates production.