The electrocatalytic hydrogenation of furanic compounds in a continuous electrocatalytic membrane reactor

Abstract

The electrocatalytic hydrogenation of biomass derived oxygenates in a continuous electrocatalytic membrane reactor presents a promising method of fuel and chemical production that minimizes usage of solvents and has the potential to be powered using renewable electricity. In this paper we demonstrate the use of a continuous-flow electrocatalytic membrane reactor for the reduction of aqueous solutions of furfural into furfuryl alcohol (FA), tetrahydrofurfuryl alcohol (THFA), 2-methylfuran (MF) and 2-methyltetrahydrofuran (MTHF). Protons needed for hydrogenation were obtained from the electrolysis of water at the anode of the reactor. Pd was identified as the most active monometallic catalyst of 5 different catalysts tested for the hydrogenation of aqueous furfural with hydrogen gas in a high-throughput reactor. Thus Pd/C was tested as a cathode catalyst for the electrocatalytic hydrogenation of furfural. At a power input of 0.1W, Pd/C was 4.4 times more active (per active metal site) as a cathode catalyst in the electrocatalytic hydrogenation of furfural than Pt/C. The main products for the electrocatalytic hydrogenation of furfural were FA (54–100% selectivity) and THFA (0–26% selectivity). MF and MTHF were also detected in selectivities of 8%. Varying the reactor temperature between 30 °C and 70 °C had a minimal effect on reaction rate for furfural conversion. Using hydrogen gas at the anode, in place of water electrolysis, produced slightly higher rates of product formation at a lower power input. Sparging hydrogen gas on the cathode had no effect on reaction rate or selectivity, and was used to examine the addition of recycling loops to the continuous electrocatalytic membrane reactor.