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.

Automated summary

Conversion of renewable compounds to versatile platform molecules over environmentally friendly heterogeneous catalysts is in high demand. Bifunctional Zr,Al-containing large-pore zeolites have been shown to be active, selective, and reusable catalysts for the transformation of biomass-derived furfural to gamma-valerolactone. Optimizing the catalyst structure and chemical composition enables achieving high yields of gamma-valerolactone comparable to or even exceeding values reported for homogeneous or heterogeneous catalysis.