(675e) Impact of Fouling on Kinetics of the Electrochemical Hydrogenation and Hydrogenolysis of Furfural in Acidic Media over Copper

Electrochemical hydrogenation and hydrogenolysis (ECH) can be used for upgrading of biomass-derived species, and as opposed to thermocatalytic process, has the benefits of producing adsorbed hydrogen for reaction in-situ and can operate at room temperature and pressure. Thermocatalytic methods require externally supplied hydrogen gas for the reduction reactions, such as hydrogenolysis and hydrogenation. This external hydrogen often comes from non-sustainable processes that produce large amounts of CO₂. Furfural (FF) is a biomass-derived species, that will form furfuryl alcohol (FA) via hydrogenation, and 2-methylfuran (MF) via hydrogenolysis. FA and MF are value added products used as a binder and a fuel additive, respectively. An important aspect to study for FF ECH is the kinetics for the process. Side reactions decrease the yield of desired products and can foul the electrode, which has negative impacts onto the desired reaction kinetics.

In this work the effect of electrode fouling on the kinetics of FF ECH to MF and FA was investigated though bulk electrolysis experiments run using fouled and fresh electrodes. Our findings on homogeneous side reactions are presented as well. Experiments were done in acidic media (0.5 M H₂SO₄) over Cu catalysts and run between -500 and -800 mV vs RHE with initial concentrations of FF between 10 and 200 mM in a temperature range of 15°C to 45°C. The amount of fouling was characterized by XPS. Our results showed that high concentrations of substrate and longer experiments lead to fouling of the electrode, which has negative impact onto desired reaction rates. Additionally, a temperature increase from 15°C to 45°C was found to decrease the mass balance closure from 88% to 70%. When the temperature changed from 35°C to 45°C between independent experiments, a 40% drop in FA yield was found after 30 minutes as well as a discolored electrolyte.