Two salicylic acid derivatives welded Zr-based hybrids relay catalysis: One-pot conversion of bio-based furfural to additive γ-valerolactone

Abstract

The development of multifunctional catalysts with multiple active sites is critical for upgrading bio-derived furfural into high-value γ-valerolactone. In this study, two Zr-based hybrid catalysts, Zr-SSA and Zr-3NSA, were synthesized via a straightforward hydrothermal method using 5-sulfosalicylic acid (SSA) and 3-nitrosalicylic acid (3NSA) as ligands coordinated with Zr⁴⁺, respectively. The sulfonic acid groups in Zr-SSA introduce significant Brønsted acidity, enabling efficient catalytic ring-opening of furfuryl alcohol to levulinate esters in alcoholic media. Besides, the nitro groups in Zr-3NSA enhance its Lewis acidity, improving its catalytic performance in transfer hydrogenation reactions. By adjusting the relative proportions of Zr-SSA and Zr-3NSA, the Brønsted-to-Lewis acidity ratio can be flexibly tuned, facilitating the cascade conversion of furfural to γ-valerolactone. Furthermore, a kinetic model was developed for this dual-catalyst relay system, enabling quantitative analysis of reaction pathways and providing mechanistic insights. This study demonstrates a novel strategy for the design of environmentally friendly and efficient Zr-based hybrid catalysts, highlighting their potential in the versatile conversion of lignocellulose-derived platform chemicals.