Effective hydrolysis of polysaccharides by activated attapulgite

BACKGROUND Hydrolysis of polysaccharides is a key step in biorefineries processes. In this study, an economic and green approach was developed to hydrolyze soluble polysaccharides (starch, inulin, etc.) into monosaccharides by a natural clay of attapulgite (ATP) modified with H 2 SO 4 (ATP  S), and the catalysts were characterized by Fourier Transform Infrared Spectroscopy (FT-IR), Pyridine FTIR Spectroscopy (pyridine-FTIR), Temperature Programmed Desorption of Ammonia (NH 3 -TPD), Thermo-Gravimetric/Differential Thermal Analyze (TG-DTA). The hydrolysis of different substrate over ATP-S was evaluated. RESULTS After H 2 SO 4 modification, the total acid sites of the catalyst ATP-S increased from 65.33 to 109.46 umol g –1 , and the surface area also increased from 81.4 to 137.3 m 2 g –1 . ATP-S shows excellent activity and stability for polysaccharides hydrolysis in aqueous system. As for inulin as reactant, 98.5% of hydrolysis ratio was obtained at the moderate temperature of 95 °C for 210 min, and 75.8% hydrolysis ratio was achieved for starch. More importantly, there is no apparent decline of the catalytic activity after 4 recycles in aqueous system. In addition, the kinetic analysis was carried out, and the activation energy of the substrates were calculated. CONCLUSION Compared with other hydrolysis processes involving enzymes and homogeneous catalysis, the process in this paper is more cost-efficient and environmentally friendly, and it can easily be scaled-up and implemented in chemical and bio-based industries. © 2021 Society of Chemical Industry (SCI).