Catalytic conversion of cellulose to chemicals in ionic liquid

A simple and effective route for the production of 5-hydroxymethyl furfural (HMF) and furfural from microcrystalline cellulose (MCC) has been developed. CoSO4 in an ionic liquid, 1-(4-sulfonic acid) butyl-3-methylimidazolium hydrogen sulfate (IL-1), was found to be an efficient catalyst for the hydrolysis of cellulose at 150 °C, which led to 84% conversion of MCC after 300 min reaction time. In the presence of a catalytic amount of CoSO4, the yields of HMF and furfural were up to 24% and 17%, respectively; a small amount of levulinic acid (LA) and reducing sugars (8% and 4%, respectively) were also generated. Dimers of furan compounds were detected as the main by-products through HPLC-MS, and with the help of mass spectrometric analysis, the components of gas products were methane, ethane, CO, CO2, and H2. A mechanism for the CoSO4-IL-1 hydrolysis system was proposed and IL-1 was recycled for the first time, which exhibited favorable catalytic activity over five repeated runs. This catalytic system may be valuable to facilitate energy-efficient and cost-effective conversion of biomass into biofuels and platform chemicals.

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► Acid ionic liquid IL-1 showed highest catalytic activity among different ionic liquids.
► The CoSO4-IL-1 system was an efficient catalyst for the hydrolysis of MCC, the conversion reached 84–85%.
► 5-HMF and furfural yields were up to 24% and 17%, respectively.
► Small amount of levulinic acid and the total reducing sugars were also generated.
► A mechanism for the hydrolysis system was proposed and IL-1 was recycled for the first time.