Biomass represents an untapped resource for achieving a circular carbon economy. Current processes for converting biomass are limited to centralized processing facilities. Electrochemical approaches are inherently modular and enable decentralized upgrading of pyrolysis oil to value-added chemicals and fuels (products). A primary component of the aqueous phase of such feedstocks are carbonyl functionalities, where benzaldehyde (BZ) represents a model compound. Selective reduction of BZ to benzyl alcohol (BnOH) can be used to understand the catalytic upgrading of pyrolysis oil to value-added products. Electrocatalytic hydrogenation (ECH) of BZ can be carried out at mild temperatures and pressure with the hydrogen required for BZ reduction coming from the protons in the solution. However, these protons can also combine in the hydrogen evolution reaction (HER) in a competitive process. Among the noble and base metals studied in the literature, palladium (Pd) is very active and has demonstrated a high faradaic efficiency (FE) for ECH of BZ relative to HER. Palladium also forms a thermodynamically stable hydride under these conditions. Prior work has shown that BZ inhibits the formation of palladium hydride under reaction conditions, whereas the presence of weaker adsorbing organics does not. However, missing is an investigation on the influence of the hydride on the ECH of BZ. The specific aims of this work investigate the effect of catalyst morphology on the surface coverage of intermediates like H and adsorbed BZ and the influence of hydride on ECH when it is thermodynamically expected. For this, we investigate high surface area Pd nanoparticle electrocatalysts and a gel network (Pd Gel) of them rich with grain boundaries and strain via cyclic voltammetry. Adsorption isotherms on these Pd catalysts show changes in hydride formation and the relative affinity of H and BZ on the Pd surface. We further study the role of hydride on ECH for different concentrations of BZ. These findings point to catalyst morphology as a further handle to manipulate activity of catalysts for ECH of BZ. Furthermore, these findings will enhance the mechanistic understanding of BZ ECH kinetics and will contribute to improving the overall efficacy of biomass conversion to biofuels.
I am a 5th year PhD Candidate in Chemical Engineering at OSU. Previously, I obtained my Maters from National University of Singapore investigating transport phenomena in all-vanadium redox flow batteries. My current research is focused on investigating material design strategies for tailoring selectivity in chemical reactions. Outside of the lab, I have participated in Meet a Scientist events at OMSI and an introductory science policy workshop in Washington DC.