Changing the Action of Iron from Stoichiometric to Electrocatalytic in the Hydrogenation of Ketones in Aqueous Acidic Media

Abstract

Cyclohexanone, a model compound chosen to conveniently represent small oxygenates present in the aqueous phase of biomass hydrothermal upgrading streams, was hydrogenated in the presence of electrodeposited iron(0) using aqueous formic or sulfuric acid as a hydrogen donor. Under these conditions, zero-valent iron is consumed stoichiometrically and serves as both a formic acid decomposition site and a hydrogen transfer agent. However, the resulting iron(II) can be used to continuously regenerate iron(0) when a potential is applied to the glassy carbon working electrode. Controlled potential electrolysis experiments show a 17% conversion of cyclohexanone (over 1000 seconds) to cyclohexanol with >80% efficiency of iron deposition from an iron(II) sulfate solution containing formic or sulfuric acid. In the absence of electrodeposited iron, formation of cyclohexanol could not be detected.

Electroreductive upgradation of biomass into high-value chemicals and energy-intensive biofuels

“…Compared to the traditional reduction pathways, ECH is more suitable for biomass upgrading, whether from an operational or economic point of view. [43][44][45][46] Along this direction, three prevalent catalytic models have been established. 46 Direct utilization of inert electrodes (e.g., Pt, Pb, and carbon electrodes) is the most well-studied catalytic method, but is not efficient enough (Fig.…”