Selective production of furfuryl alcohol from furfural by catalytic transfer hydrogenation over commercial aluminas

Three commercial aluminas (gamma-Al2O3) have been evaluated as inexpensive catalysts in the Meerwein-Ponndorf-Verley (MPV) reaction to reduce furfural (FUR) to furfuryl alcohol (FOL), using isopropanol (i-Pr-OH), 2-butanol (2-bu-OH) and cyclohexanol (CH-OH) as sacrificing alcohol under mild conditions. All gamma-Al2O3 have been characterized by XRD, Al-27 NMR and FT-IR spectroscopies, NH3-TPD and XPS. The aluminas are active catalysts, giving rise to FOL as main product, with a yield higher than 90% after 6 h at 150 degrees C. The catalytic data also reveal that linear alcohols, such as isopropanol and 2-butanol, lead to higher FUR conversion values in comparison to cyclohexanol. However, the presence of H2O in the reaction medium has an adverse effect in FUR conversion by the transformation of active Lewis acid sites into Bronsted ones, which are inactive in the MPV reaction.