Catalytic Transfer Hydrogenation of Furfural to Furfuryl Alcohol with Recyclable Al-Zr@Fe Mixed Oxides

A series of magnetic, acid/base bifunctional Al–Zr@Fe₃O₄ catalysts were successfully prepared by a facile coprecipitation method and utilized in the catalytic transfer hydrogenation (CTH) of furfural to furfuryl alcohol with 2-propanol as hydrogen source. The physicochemical properties and morphologies of the as-prepared catalysts were characterized by various techniques, including XRD analysis, N2 physisorption, vibrating sample magnetometry, thermal gravimetry analysis, X-ray fluorescence spectroscopy, NH₃/CO₂ temperature-programmed desorption, SEM, and TEM. The Al₇Zr₃@Fe₃O₄(1/1) catalyst with a Al³⁺/Zr⁴⁺/Fe₃O₄ molar ratio of 21:9:3 was found to exhibit a high furfuryl alcohol yield of 90.5 % in the CTH from furfural at 180 °C after 4 h with a comparatively low activation energy of 45.3 kJ mol⁻¹, as calculated from the Arrhenius equation. Moreover, leaching and recyclability tests confirmed Al₇Zr₃@Fe₃O₄(1/1) to function as a heterogeneous catalyst that could be reused for at least five consecutive reaction runs without significant loss of catalytic activity after simple recovery by an external magnet. Notably, the catalyst proved also efficient for hydrogenation of other biomass-derived furanic aldehydes.