Stabilizing the interfacial Cu0-Cu+ dual sites toward furfural hydrodeoxygenation to 2-methylfuran via fabricating nest-like copper phyllosilicate precursor

Furfural hydrodeoxygenation (HDO) to 2-methylfuran (2-MF) is one of the most momentous routes in upgrading of biomass platform molecules, where the most universally employed active metal—Cu often suffers from thermal sintering and poor stability in spite of its brilliant effect on the activation of carbonyl. In this study, we designed a highly active and stable Cu/SiO2 nanocatalyst by fabricating nest-like nanotubes (CuSi-N) through a two-step method: preparation of amorphous copper phyllosilicate through ammonia evaporation, followed by a further hydrothermal crystallization with the assistance of P123. Notably, the CuSi-N catalyst gives a 2-MF space–time yield of 46.6 mmol·gcat−1·h−1, which is much larger than CuSi-A prepared by the conventional ammonia-evaporation method. A combination study (Raman spectra, TEM, H2-TPR, XPS, CO-DRIFTS and NH3-TPD) verifies that the nest-like precursor enhances the CuOx-SiO2 interaction, which results in a promoted Cu+ abundance as well as thermal stability of the active sites. In situ FTIR spectra of adsorbed molecules, coupled with density functional theory calculations, prove that Cu+ sites are responsible for the adsorption and activation of both furfural (FAL) and intermediate furfuryl alcohol (FOL) while Cu0 sites account for H2 dissociation. This work discloses the significance of the synergy effect of Cu0-Cu+ dual sites of Cu/SiO2 catalysts which could be employed for the other HDO reactions in the upgrading process of biomass.