Study On The Acid Catalytic Alcoholysis Reaction Of Cellulose Promoted By Pretreatment

Cellulose transforms into monosaccharides,and then through fermentation and other means to produce ethanol or other high value-added chemicals is one of the hot spots of cellulose utilization.In this paper,the effects of supercritical CO2(scCO2)pretreatment on the alcoholysis of 1-propylsulfonate-3-methylimidazolium bisulfate([C3SO3Hmim]HSO4)were studied.The effects of pretreatment conditions and alcoholysis reaction conditions on the yield of methyl glucosides were investigated.The results showed that the pretreatment of scCO2 could significantly increase the yield of methylglucoside.The optimum conditions of scCO2 pretreatment were:140?,25 MPa and 2.0 h.When the concentration of[C3SO3Hmim]HSO4 was 1.2 g/L,the yield of methyl glucosides reached the highest value of 39.1%at 205? for 2.0 h.Then,the effect of pretreatment of 1-allyl-3-methylimidazolium chloride([Amim]Cl)on the alcoholysis of cellulose catalyzed by phosphotungstic acid(HPW)was studied.It was found that[Amim]Cl pretreatment reduced the crystallinity of cellulose and the cellulose crystal form is transformed from cellulose ? to cellulose ? to promote the subsequent saccharification of cellulose.When HPW concentration was 30 g/L,the regenerated cellulose,obtained by[Amim]Cl pretreatment at 110? for 35 min,reacted with methanol at 170? for 165 min,and the yield of methyl glucosides reached the highest value of 70.2%.Finally,the carbon-supported silicotungstic acid(HSiW/C)catalyst was prepared,and the structure,activity and stability of the catalyst were characterized.HSiW/C was used to catalyze the alcoholysis of regenerated cellulose.The effects of alcoholysis temperature,time and the amount of catalyst on the yield of methyl glucoside were investigated.It was found that when the mass ratio of catalyst to regenerated cellulose was 2:1,the yield of methylglucoside was up to 19.3%at 170? for 6.0 h.