Visible-light-driven coproduction of diesel precursors and hydrogen from lignocellulose-derived methylfurans

Abstract

Photocatalytic hydrogen production from biomass is a promising alternative to water splitting thanks to the oxidation half-reaction being more facile and its ability to simultaneously produce solar fuels and value-added chemicals. Here, we demonstrate the coproduction of H2 and diesel fuel precursors from lignocellulose-derived methylfurans via acceptorless dehydrogenative C−C coupling, using a Ru-doped ZnIn2S4 catalyst and driven by visible light. With this chemistry, up to 1.04 g gcatalyst−1 h−1 of diesel fuel precursors (~41% of which are precursors of branched-chain alkanes) are produced with selectivity higher than 96%, together with 6.0 mmol gcatalyst−1 h−1 of H2. Subsequent hydrodeoxygenation reactions yield the desired diesel fuels comprising straight- and branched-chain alkanes. We suggest that Ru dopants, substituted in the position of indium ions in the ZnIn2S4 matrix, improve charge separation efficiency, thereby accelerating C−H activation for the coproduction of H2 and diesel fuel precursors. Biomass can be used to scavenge photogenerated holes in photocatalytic hydrogen production, but the oxidized molecules that form are not always useful products. Here, the authors use Ru-ZnIn2S4 to photocatalyse the dehydrogenative C−C coupling of lignocellulose-derived methylfurans, forming both hydrogen and diesel fuel precursors.