Catalytic conversion of cellulose to 5-hydroxymethyl furfural using acidic ionic liquids and co-catalyst

► The Cu2+ plays an important role in the conversion of MCC to HMF. ► [C4SO3Hmim][CH3SO3] shows higher catalytic activity in hydrolysis of cellulose. ► A mechanism to explain the high activity of CuCl2 in [C4SO3Hmim][CH3SO3] is proposed.