Selective hydrogenolysis of furfuryl alcohol towards 1,5-pentanediol over a Co/CeO2 catalyst†

Abstract

The selective hydrogenolysis of C–O bonds in furfuryl alcohol (FFA) into high-value pentanediols is of great significance to the production of bio-based polyesters and polyurethanes. Herein, a supported 5Co/CeO₂ catalyst was designed to facilitate the selective conversion of FFA to 1,5-pentanediol (1,5-PeD). Complete conversion of FFA was achieved within 1 h at 170 °C and 4 MPa H₂, with a 54% selectivity to 1,5-PeD. The production rate reached 13 mol_1,5-PeD mol_Co⁻¹ h⁻¹, the highest value reported so far. The kinetic studies revealed that the reaction rate had a first order dependence on both hydrogen pressure and FFA concentration, with an apparent activation energy of 76 kJ mol⁻¹. Characterization using H₂-TPR, H₂-TPD, and XPS revealed that compared with 5Co/MgO and 5Co/ZrO₂, the 5Co/CeO₂ catalyst had the highest Co⁰/Co²⁺ ratio (0.69) and abundant oxygen vacancies. Moreover, the oxygen vacancy concentration increased with the reduction temperature of 5Co/CeO₂, and linearly correlated with the reaction rate. Raman, FFA-DRIFTS, and substrate control experiments showed that FFA was adsorbed on oxygen vacancies with both the furan oxygen and hydroxyl oxygen atoms. This unique adsorption mode facilitated the ring opening reactions. Co⁰ was responsible for hydrogen activation while the oxygen vacancies from both the interfacial Co²⁺ and CeO₂ were responsible for FFA adsorption. The good synergy between the Co⁰ and the adjacent oxygen vacancies allows the efficient conversion of FFA to 1,5-PeD. This study provides a useful guideline for the design of non-precious metal catalysts for upgrading other biomass-derived molecules via selective hydrogenolysis of C–O bonds.