Hydrolysis of Cellulose using boronic-acid multifunctional carbocatalysts

Abstract

Background Developingeffective and sustainable catalysts for cellulose hydrolysis is crucial for transforming this abundant biopolymer into renewable chemicals and biofuel. Carbonaceous solid acids are promising catalysts for this reaction due to their low cost, chemical and hydrothermal stability, tunable surface, and high affinity for cellulose. MethodsWe developed multifunctional carbocatalysts for cellulose hydrolysis by introducing boronic groups and weak acid sites along with high-density sulfonic acid through borylation of mesophase pitch carbon (MPC) followed by sulfonation. The functionalized MPC was characterized using various techniques, including FT-IR, XPS, SS-NMR, Raman spectroscopy, and TGA. Significant findingsThe results of surface characterization revealed the successful introduction of multifunctional groups on the peripheral surface of MPC. This carbocatalyst can effectively hydrolyze pretreated cellulose into glucose, resulting in a maximum yield of 64 % in water at 180 °C for 3 h. Boronic groups and weak acid sites could mediate the interaction of cellulose molecules with catalyst surface to enhance the catalytic hydrolysis. The apparent activation energy for breaking the glycosidic bonds using the functionalized MPC is 99 kJ/mol, which is lower than the one derived from homogeneous acids. Furthermore, the carbocatalyst is recyclable at least four cycles prior to the significant loss for reactivity.