Magnetic hydrotalcites as solid basic catalysts for cellulose hydrolysis

Abstract

Magnetic Mg–Fe–CO3 hydrotalcites (LDHs) with different Mg/Fe molar ratios were prepared and their microstructure and surface chemical properties were characterized. The particles were used to hydrolyze cellulose with β-1,4-glycosidic bonds. The catalytic activity relating to the electron–hole pairs, basicity, crystallinity and specific surface area depended on the Mg/Fe molar ratio. The LDH with Mg/Fe molar ratio of 3.0 (LDH-3) possessed the best crystallinity, the strongest ability to trap electrons, the highest basicity and specific surface area, exhibiting the highest catalytic activity in the cellulose hydrolysis. It could be because of the high crystallinity and basicity, especially plentiful strong basic sites, made the LDH-3 a strong ability to trap electrons leading to great affinity for β-1,4-glycosidic bonds of cellulose. The LDH-3 showed a maximum yield (46.5%) of soluble reducing sugars with high glucose selectivity (84.4%) at 150°C for 24h. Moreover, the solid catalyst could be easily separated and possibly reused.