Electrocatalytic hydrogenation of the formyl group and heteroaromatic ring in furfural on activated carbon cloth-supported ruthenium†

Electrocatalytic hydrogenation (ECH) was explored as a mild technique (≤50 °C under atmospheric pressure) to produce valuable products from furfural, a promising biomass-derived platform chemical. In situ hydrogen equivalents made by water splitting were used to reduce the formyl group and saturate the heteroaromatic ring of furfural on an activated carbon cloth-supported ruthenium electrocatalyst. A systematic study was conducted to understand the relationship between the reaction conditions and the products. The factors analyzed include catholyte solution organic co-solvent content, catholyte solution acid content, and temperature. Acidity of the catholyte solution had the most significant effect on the yield of tetrahydrofurfuryl alcohol (THFA). The highest THFA yield was obtained in mildly acidic catholyte solutions (0.02 M HCl and 0.002 M HCl–0.02 M NaCl). The low carbon mole balance closure in the experiments was attributed to the side reactions of the reactants, intermediates, and products. The effects of current density on faradaic efficiency and of the functional groups attached to the furan ring on the formation of saturated heterocyclic products were also explored.