Hydrolysis of cellulose is highly dependent upon reaction temperature. Dilute sulfuric acid exhibited highly catalytic performance for cellulose hydrolysis at temperatures above 180-240 °C, but efficient hydrolysis did not occur at 100 °C[81]. When supercritical water was used as a medium for hydrolysis, harsh conditions such as high temperature (e. g., 400 °C), and high pressure (e. g., 30 MPa) were required

[82, 83]. Most solid acid catalysts have higher activation energy for cellulose conversion into glucose than that for sulfuric acid (170 kJ/mol) under optimal conditions except carbonaceous solid acid catalysts (110 kJ/mol) [41].

Most experiments were conducted at 120-190 °C [1]. Lai et al. [41] performed cellulose hydrolysis with sulfonic group functionalized magnetic SBA-15 catalyst (Fe3O4-SBA-SO3H) in [BMIM][Cl] at 120 °C, and a 50 % glucose yield was ob­tained in 3h. The low reaction temperature and short reaction time are attributed to the high solubility of [BMIM][Cl] to dissolve cellulose by disrupting hydrogen bonds among the molecules. Suganuma et al. [42] demonstrated that the formation rate of glucose and water-soluble |5-1,4-glucans on carbonaceous acid catalysts increased exponentially with temperature from 60 to 120 °C. When temperature increased from 60-90 °C to 90-120 °C, the apparent activation energy decreased from 128 to 44 kJ/mol. At higher temperature (180 °C), the yield of glucose markedly decreased from 43 % to 3 % due to the formation of side-products, such as levoglucosan, cellobiose, maltose, levulinic, and formic acids [41, 42].