Length 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.g(cat)(-1).h(-1), which is much larger than CuSi-A prepared by the conventional ammonia-evaporation method. A combination study (Raman spectra, TEM, H-2-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 Cu-0 sites account for H-2 dissociation. This work discloses the significance of the synergy effect of Cu-0-Cu+ dual sites of Cu/SiO2 catalysts which could be employed for the other HDO reactions in the upgrading process of biomass.

Automated summary

In this study, a highly active and stable Cu/SiO2 nanocatalyst was designed and prepared through a two-step method. The catalyst showed a significantly improved yield of 2-methylfuran in the upgrading process of biomass. The enhanced CuOx-SiO2 interaction in the catalyst resulted in higher Cu+ abundance and thermal stability of the active sites.