Bimetallic CuRu/Al2O3 catalyst for highly selective hydrogenation of furfural to furfuryl alcohol

Abstract

The selective hydrogenation of furfural (FAL) to furfuryl alcohol (FA) derived from biomass sources is crucial for alleviating the energy crisis. Cu-based catalysts with low cost and high selectivity are widely employed in this reaction. To enhance the activity of Cu-based catalysts under mild conditions, this study synthesized the bimetallic CuRu/Al₂O₃ catalysts with varying Ru contents via the deposition–reduction method. The physicochemical properties characterized by XRD, TEM, H₂-TPR, H₂-TPD, XPS, and FT-IR techniques revealed that Ru doping promoted the dispersion of Cu species and improved the H₂ adsorption ability. Additionally, strong Cu–Ru interactions, which derived from electron transfer from Cu to Ru, enhanced the metal reducibility. As a result, the bimetallic 5Cu1Ru/Al₂O₃ catalyst exhibited the outstanding performance of 99.9% FAL conversion and 99.9% FA selectivity within 4 h at 90 °C under 1 MPa H₂ pressure, with an exceptionally low apparent activation energy of 118.4 kJ mol⁻¹. TG analysis indicated that increasing Ru content lowered the temperature of FA desorption, thereby easily re-exposing the active sites for the reaction cycle. The current investigation provides a reference for designing the efficient bimetallic catalysts to achieve high FAL conversion under mild conditions.