Deciphering the role of acid-treated clay towards selective catalysis of glucose to HMF

Abstract

5-Hydroxymethylfurfural (HMF), a key biomass-derived platform molecule, serves as a precursor for fuels, additives, and value-added chemicals. Although, solid acid catalysts comprising Lewis–Brønsted acid sites have been widely investigated for cascade glucose conversion to HMF; however, the mechanistic principles governing site optimisation are poorly understood. Herein, we unravel the effect of mild acid treatment on the Brønsted–Lewis acid pairs of clay and their synergistic effect on the performance of glucose transformation to HMF. Notably, the formic acid-treated clay (FA-CL) catalyst facilitates aqueous phase one-pot tandem catalysis for glucose conversion to HMF, yielding 58.2% HMF at 145 °C and excellent recyclability up to ten cycles. Mild acid activation of the clay leads to distinct Lewis–Brønsted acidity profiles while preserving structural integrity, promoting synergistic catalysis and cooperativity between both acid sites toward selective HMF formation.