Hydrolysis of mechanically pre-treated cellulose catalyzed by solid acid SO42--TiO2 in water-ethanol solvent

An efficient catalyst SO42--TiO2 (ST) from industrial metatitanic acid has been successfully prepared to catalyze hydrolysis of ball-milling cellulose. The results show that the highest catalytic efficiency is obtained for ST calcined at 450 degrees C (ST-450) with the yield of 21.8% glucose, 13.0% 5-HMF and 4.2% furfural at 200 degrees C for 30 min. The ball milling of cellulose and solid acid catalyst significantly enhances the cellulose hydrolysis. The high Lewis to Bronsted acid sites ratio for ST-450 induced by bidentate ligands between SO42- and TiO2 benefits high organics yield, and high total acid sites contribute to the high cellulose conversion. The large pore volume of 0.29 cm(3).g(-1) and appropriate pore size of 7.35 nm of ST-450 also contribute to the high performance. High reaction temperature over 200 degrees C exhibits negative effect on glucose and 5-HMF yield due to undesired side reactions, while furfural product is stable in the reaction system. The bidentate ligands between SO42- and TiO2 are considered as active acid sites for cellulose hydrolysis in water-ethanol solvents. (C) 2019 The Chemical Industry and Engineering Society of China, and Chemical Industry Press Co., Ltd. All rights reserved.