Hydrolysis of cellulose catalyzed by sulfonated poly(styrene-co-divinylbenzene) in the ionic liquid 1-n-butyl-3-methylimidazolium bromide

The hydrolysis of cellulose catalyzed by sulfonated poly(styrene-co-divinylbenzene) (SPS-DVB) was carried out in the ionic liquid 1-n-butyl-3-methylimidazolium bromide (BMIMBr), in which the reaction medium BMIMBr and sulfate polymer catalyst can be recovered. The influence of the amount of catalyst, water and ionic liquid, reaction conditions including reaction time and temperature was investigated in detail. The recovery of BMIMBr was performed based on using Aliquat 336 and naphthalene-2-boronic acid to extract the sugar derived from the hydrolysis of cellulose, and it was reused without further treatment. It was found that ionic liquid possessed excellent stability, and the conversion of cellulose almost kept constant during the recycles. The fresh and recovered sulfonated catalysts were characterized by means of TGA and IR, and the recovered catalyst was reused with/without treatment with acid. The catalytic activity almost kept constant in the case of regenerating by sulphuric acid prior to reuse, but a significant loss of activity was observed without regeneration. The results revealed that there may be an ion exchange process between the acidic sites of sulfonated catalyst and ionic liquid during the hydrolysis of cellulose.