Organic acid-assisted design of zirconium-lignocellulose hybrid for highly efficient upgrading levulinic acid to γ-valerolactone

Abstract

Acid treatment is the key to improve the physicochemical properties of metal-lignocellulosic hybrid, thus contributing to the catalytic performance for catalytic transfer hydrogenation (CTH) of carbonyl compounds to their corresponding alcohols. Herein, a series of organic acids were introduced to assist the design of Zr-Pennisetum sinese hybrid. Comprehensive studies demonstrated the dramatic changes of specific surface and acid/base sites of the prepared hybrid. Remarkably, formic acid-assisted Zr@PS-FA possessed the largest surface area and enhanced interaction effects between acids (Lewis acid and Brønsted acid) and Lewis base sites, which exhibited excellent catalytic activity for CTH of levulinic acid to γ-valerolactone with a high yield of 95.6% in isopropanol under moderate reaction conditions (180 °C and 1.5 h). Zr@PS-FA also showed remarkable cycle stability, and it could be consecutively used at least six runs without a significant loss in catalytic activity. More gratifyingly, Zr@PS-FA displayed a superior universality for CTH of various carbonyl compounds to their corresponding alcohols, demonstrating great potential for upgrading biomass-derived aldehydes/ketones.