(621o) Electrocatalytic Processing of Biorenewables for Generation of Electricity, Chemicals and Fuels
As an abundant, inexpensive and renewable natural resource, biomass is expected to play a significant role in our future energy and chemical landscape. The U.S. DOE has identified some platform compounds (or building blocks, i.e. glycerol, levulinic acid, etc.) that can be readily derived from biomass, and 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 biomass platform compounds for generation of electricity, chemicals and fuels. We investigated electrocatalytic selective oxidation of polyols for cogeneration of higher-valued chemicals and electricity, and discovered that the degree of glycerol oxidation on Au nanoparticles can be well tuned with anode potential to produce tartronate, mesoxalate or glycolate, and the mechanism of potential-controlled glycerol electro-oxidation has been proposed. This may open a new route for the controllable transformation of biomass compounds with poly- or multi-functional groups into valuable chemicals. We further developed a direct crude glycerol (88%) anion-exchange membrane fuel cell with our self-prepared carbon nanotube supported surface dealloyed PtCo nanoparticle anode catalyst (0.5 mgPt cm-2) and Fe-based cathode catalyst, which demonstrated a very high output peak power density of 268 mW cm-2 and decent operation stability and system durability. We also explored electrocatalytic processes to store renewable electricity in biofuels, and have demonstrated electrocatalytic reduction of levulinic acid (LA) 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 (co-produced with LA in cellulose hydrolysis stream) can increase the rate of electro-reduction of LA to VA. Our work shows promise for direct electrocatalytic processing of crude biomass streams for electrical energy and biofuels production.