1-(1-Propylsulfonic)-3-methylimidazolium chloride acidic ionic liquid catalyzed hydrolysis of cellulose in water: Effect of metal ion co-catalysts

• Mn2 +, Fe3 +, Co2 + co-catalysts enhance TRS yields in the cellulose hydrolysis.
• Hydrolysis using Mn2 + co-catalyst gave the highest TRS yield of 91.9% at 170 °C.
• Ni2 +, Cu2 +, Zn2 + and La3 + show no significant TRS yield enhancements.
• All metal chlorides except Cr3 + show no effect on glucose yields.

The effect of eight metal ions, Cr3 +, Mn2 +, Fe3 +, Co2 + Ni2 +, Cu2 +, Zn2 + and La3 + on 1-(1-propylsulfonic)-3-methylimidazolium chloride acidic ionic liquid catalyzed hydrolysis of cellulose in water was studied at 140–170 °C. Mn2 +, Fe3 +, and Co2 + as co-catalysts produced significant enhancements in total reducing sugar (TRS) yields, with Mn2 + showing the highest activity. Mn2 + as co-catalyst produced 91.8, and 91.9% TRS yields, whereas samples without Mn2 + gave 28.0 and 28.7% yields at 160 and 170 °C respectively. The observed activation energies for cellulose hydrolysis without a co-catalyst and with Mn2 + co-catalyst are 78.1 ± 1.4 and 32.8 ± 4.9 kJ·mol− 1 respectively.