Dual acidic mesoporous KIT silicates enable one-pot production of γ-valerolactone from biomass derivatives via cascade reactions

Abstract

γ-Valerolactone (GVL) is an interesting bio-based platform molecule that is utilized as green solvent and a versatile building block for the synthesis of bio-fuels and chemicals. Herein, an investigation on the efficient production of GVL from biomass-based carbonyl compounds such as furfural, levulinic acid, and its esters using 2-propanol as H-donor and solvent over stable Zr-incorporated mesoporous silica (KIT-5) catalysts was presented. Both Lewis and Brønsted acid sites were generated by the introduction of Zr into KIT-5, and the acid density of the resulting Zr-KIT-5(Si/Zr) could be controlled by simply adjusting Si/Zr molar ratio. Among these bifunctional catalysts, Zr-KIT-5(10) showed superior catalytic performance in the production of GVL (>91% selectivity) from biomass-derived carboxides (ca. 94% conversion), which was demonstrated to positively correlate with its large amount of acidic sites and facile access of active sites to interconnected pores. Moreover, the spent catalyst held about 90% of its original activity in the sixth run. Due to the presence of Brønsted and Lewis dual acidic sites in Zr-KIT-5, the direct conversion of furfural to GVL was also permitted in a single pot via tandem reactions involving hydrogenation, ring-opening, secondary hydrogenation, and subsequent cyclization.