Abstract
The electrocatalytic hydrogenation (ECH) of biomass-derived levulinic acid (LA) is a promising strategy to synthetize fine chemicals under ambient conditions by replacing the thermocatalytic hydrogenation at high temperature and high pressure. Herein, various metallic electrodes were investigated in the ECH of LA in a H-type divided cell. The effects of potential, electrolyte concentration, reactant concentration, and temperature on catalytic performance and Faradaic efficiency were systematically explored. The high conversion of LA (93%) and excellent “apparent” selectivity to valeric acid (VA) (94%) with a Faradaic efficiency of 46% can be achieved over a metallic lead electrode in 0.5 M H2SO4 electrolyte containing 0.2 M LA at an applied voltage of −1.8 V (vs. Ag/AgCl) for 4 h. The combination of adsorbed LA and adsorbed hydrogen (Hads) on the surface of the metallic lead electrode is key to the formation of VA. Interestingly, the reaction performance did not change significantly after eight cycles, while the surface of the metallic lead cathode became rough, which may expose more active sites for the ECH of LA to VA. However, there was some degree of corrosion for the metallic lead cathode in this strong acid environment. Therefore, it is necessary to improve the leaching-resistance of the cathode for the ECH of LA in future research.
Highlights
Biomass energy, derived directly or indirectly from the photosynthesis of green plants, is a unique renewable carbon source
The hydrogen evolution reaction (HER) mainly competes with electrocatalytic hydrogenation (ECH), and it is necessary to find a way to suppress HER or achieve high conversion and good selectivity. When it comes to the ECH of levulinic acid (LA), Schröder first proposed a two-step electrochemical conversion of LA to octane via valeric acid (VA) over Pb and Pt electrodes, and clarified the application of electrochemistry in the production of renewable chemicals and biofuels [21]
PEER REVIEW and dependence relations coexist between the ECH of
Summary
Biomass energy, derived directly or indirectly from the photosynthesis of green plants, is a unique renewable carbon source. The selectivity to the target products can be controlled by adjusting the cell potential/current density, temperature, electrolyte pH, and so on [14] Another attractive feature is that the electrical energy required for the reaction can be obtained from renewable energy, such as wind and solar [15,16]. The hydrogen evolution reaction (HER) mainly competes with ECH, and it is necessary to find a way to suppress HER or achieve high conversion and good selectivity. When it comes to the ECH of LA, Schröder first proposed a two-step electrochemical conversion of LA to octane via VA over Pb and Pt electrodes, and clarified the application of electrochemistry in the production of renewable chemicals and biofuels [21]. This work contributes knowledge about the reaction system for the ECH of LA from the perspective of stability and reactivity, and provides a meaningful guidance for the design of efficient metal electrocatalysts for large-scale biomass upgrading applications
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