Abstract
Hydrodeoxygenation is a promising method for conversion of lignin-derived oxygenated aromatics, which constitute 2-5 wt.% of pyrolytic bio-oil, to fungible hydrocarbon fuels. The following study investigates the electrocatalytic reduction of alkyl and allyl guaiacols (e.g. eugenol) to hydrocarbons using an electrocatalytic approach. Supported bimetallic electrocatalysts that combine an oxophilic and a hydrogenating metal were developed and characterized for this application. The ability to carry out the hydrodeoxygenation reactions under mild conditions (low temperature and ambient pressure) represents a significant advantage over the traditional thermocatalytic approach that is carried out at high temperatures and pressures. Furthermore, the hydrogen requirement of the process is fulfilled in situ by water splitting. The use of bimetallic catalysts in hydrodeoxygenation research has rapidly increased in recent years, but only a few reports of their use in electrocatalytic reactions have appeared. This study demonstrates that bimetallic catalysts can electrocatalytically hydrodeoxygenate a biomass-derived oxygenated aromatic to a hydrocarbon in a "one-pot" approach. Analyses were performed in batch mode using H-type electrochemical cells, with reactants and products quantified using GC/MS. To maximize the yield of desired products, electrolyte pH, temperature, and loading of the two metals on the support were optimized. Moreover, the effects of initial substrate concentration and current density on the faradaic efficiency of the process were analyzed.