Solvent-mediated selectivity control of furfural hydrogenation over a N-doped carbon-nanotube-supported Co/CoOx catalyst

During biomass constituent conversion, solvent choice often plays a critical role in determining product selectivity and reaction pathways. However, the role of the solvent remains poorly understood. In this study, the role of the solvent in furfural (FFA) conversion over a Co/CoO_x catalyst supported on N-doped carbon nanotubes (Co/CoO_x @N-CNTs) was investigated. In water, cyclopentanone (CPO)/cyclopentanol was produced with high selectivity via Piancatelli rearrangement. In ethanol, tetrahydrofurfuryl alcohol (THFOL) synthesized via furan ring saturation was the major product. The presence of Brønsted acid sites (BASs) in water and the participation of four hydrogen atoms from water molecules promoted FFA conversion via the CPO pathway. By contrast, the absence of BASs in ethanol and the participation of three hydrogen atoms from ethanol molecules resulted in the THFOL pathway being dominant. Furthermore, both thermodynamic properties and oxygen vacancies were found to affect FFA conversion.