Solvent-induced one-pot catalytic conversion of xylose to high yield γ-valerolactone over Zr-Beta zeolite

Abstract

The efficient production of γ-valerolactone (GVL) with high yield directly from xylose is of particular interest but remains a great challenge due to the long reaction path. We herein developed a facile catalytic system to directly convert xylose to GVL with a record-high yield of 54.3 %, employing β-zeolite supported Zr-based catalyst in 1,4-dioxane/isopropanol co-solvent. Using Zr(NO₃)₄·5 H₂O as the Zr sources resulting in well-retained β-zeolite structure, larger surface area and pore volume and better dispersion of Zr species, as well as balanced acidic sites where higher amount of Brønsted acid sites promoted the ring-opening of furfural alcohol for this cascade reaction. Notably, the introduction of 1,4-dioxane facilitated the in situ formation of furfural (i.e. yield-determining step) by diluting the competitive adsorption behavior between isopropanol and xylose, allowing more xylose molecules to access the active center, thus promoting the sequential production of GVL with unexpectedly high yield. The present work provides a efficient and straightforward preparation of GVL from xylose, paving the pathway towards higher atom economy.