A combo Zr-HY and Al-HY zeolite catalysts for the one-pot cascade transformation of biomass-derived furfural to γ-valerolactone

Abstract A highly efficient catalyst system was developed for the one-pot transformation of furfural to γ-valerolactone (GVL) in an open system. The cascade of two Meerwein Ponndorf Verley (MPV) reductions, ring-opening and esterification reactions was catalyzed by a physical mixture of Zr- and Al-HY zeolites where the proportion and strength of Lewis and Bronsted acid sites could be independently optimized. The excellent activity of Zr-HY zeolites for the MPV reduction of furfural and levulinate ester with 2-pentanol as hydrogen donor was attributed to the larger pore size of HY-zeolites and stronger Lewis acidic sites compared to Zr-Beta. Al-HY zeolites were more effective as Bronsted acid than Al-Beta because they converted furfuryl ether to levulinate ester rather than to β-angelica lactone. The dual catalytic system comprising Zr-HY (Si/Zr 20) and Al-HY (Si/Al 6) exhibited remarkably high catalytic activity with GVL yields of 85% after only 5 h at 120 °C.