Optimization of Zr-Al-USY and Zr-Al-Beta zeolites catalysts for a one-pot cascade transformation of furfural to γ-valerolactone

Conversion of renewable compounds to versatile platform molecules over environmentally friendly heteroge-neous catalysts is of increasing demand. Bifunctional Zr,Al-containing large-pore zeolites stand as active, se-lective and reusable solid catalysts for a one-pot cascade transformation of biomass-derived furfural to gamma-valerolactone, a platform molecule opening the way to various valuable chemicals. However, the influence of zeolite structure type and the ratio between Al-and Zr-associated acid sites on the outcome of this catalytic reaction has not been fully elucidated. Here we have compared the performance of the most efficient large-pore zeolites USY and Beta with systematically varied Al/Zr ratios for the one-pot synthesis of gamma-valerolactone from furfural using 2-propanol or 2-pentanol as reacting solvents. The optimization of the catalyst structure (USY) and chemical composition (Al/Zr = 0.6) enables to achieve the yield of targeted gamma-valerolactone comparable to or even exceeding the values previously reported for homogeneous or heterogeneous catalysis (88% after 24 h at 120 degree celsius). The remarkable catalytic performance of the optimized Zr-Al-USY catalyst was related to the balanced ratio between Zr-and Al-associated acid sites catalyzing different steps of the studied cascade reaction.