Catalytic transfer hydrogenation of levulinic acid to γ-valerolactone over an acids-base trifunctional Hf-bagasse coordination complex derived catalyst

Abstract

Both value-added utilization of agricultural waste to prepare catalytic materials and selective conversion of biomass-based carbonyl compounds are hot topics. Herein, sugarcane bagasse (SB), a main by-product of cane sugar manufacturing industry, was directly assembled with HfCl4 and methanesulfonic acid (MSA) via a one-step hydrothermal method for scalable preparation of Hf-containing coordination complex (Hf@SB-MSA). Characterization results revealed that the coordination between Hf4+ and phenolic hydroxyl, alcohol hydroxyl, carboxyl groups in SB resulting in the formation of Lewis acid (LA) and Lewis base (LB) sites, while sulfonic group in MSA providing Brønsted acid (BA) sites. The cooperative role of LA, BA and LB in Hf@SB-MSA delivered prominent catalytic performance for catalytic transfer hydrogenation (CTH) of levulinic acid (LvA) to γ-valerolactone (GVL) with isopropanol as solvent and H-donor at mild reaction conditions (GVL yield was up to 99.1%). Heterogeneity and recycling experiments further revealed the good recyclability of Hf@SB-MSA, which can be easily separated from the reaction mixture by filtration and repetitively used at least five reaction runs without an obvious loss of activity. More gratifyingly, Hf@SB-MSA also displayed superior universality for the CTH of various carbonyl compounds to their corresponding alcohols with yields up to 90%.