Synthesis of a silica-immobilized Brönsted acidic ionic liquid catalyst and hydrolysis of cellulose in water under mild conditions

A silica immobilized imidazolium-type acidic ionic liquid catalyst was shown to be a better catalyst than n-propylsulfonic acid silica (PrSO3H-SiO2) and sulfonic acid silica (SO3H-SiO2) for the hydrolysis of untreated Sigmacell Cellulose (DP ~ 450) in water. For example, new catalyst produced the highest TRS yield of 48.1% after 3 h at 190 °C, whereas cellulose samples heated with PrSO3H-SiO2 and SO3H-SiO2 catalysts produced only 19.9% and 13.2% TRS yields, respectively, under identical conditions. The new catalyst could be recycled up to four cycles with a small loss in catalytic activity.