Ring-opening of furfuryl alcohol to pentanediol with extremely high selectivity over Cu/MFI catalysts with balanced Cu0–Cu+ and Brønsted acid sites

Abstract

Biomass-based chemicals as a renewable alternative to petroleum-based chemicals are of great significance. The conversion of biomass-based furfuryl alcohol to pentanediol, including 1,5-pentanediol and 1,2-pentanediol, is explored over a series of bifunctional Cu/MFI catalysts in a continuous-flow reactor. These catalysts are synthesized by supporting copper nanoparticles on MFI zeolites with varying molar ratios of SiO₂/Al₂O₃. Among them, the Z60-10Cu catalyst containing balanced Cu⁰–Cu⁺ and Brønsted acid sites exhibits excellent performance, and a high furfuryl alcohol conversion of 99.5% and selectivity of 85.2% for 1,5-pentanediol (69.2%) and 1,2-pentanediol (16.0%) could be achieved (hydrogen pressure: 2.5 MPa) at 160 °C. The experimental results and the results obtained using the DFT technique revealed that the high catalytic activity realized during the processes of ring-opening and hydrogenation could be attributed to the synergistic effect between the Cu species and Brønsted acid sites. The Brønsted acid sites on the Si(OH)Al groups significantly affect the ring-opening process of furfuryl alcohol. The methoxy group on furfuryl alcohol adsorbs on the Cu⁺ sites, and the hydrogenation saturation of the ring-opening intermediate is realized under the influence of the activated hydrogen units on the Cu⁰ sites. The results reported herein could help promote the continuous production of high value-added pentanediol from biomass-based raw materials in the presence of non-noble metal catalysts. An economical and feasible path for the transformation of biomass resources into high value-added fine chemicals could also be developed.