Degradation Of Cellulose In Ionic Liquid And Water Catalyzed By Acids

Developing new sustainable resoureces has become the inevitable choice to substitute fordwindling fossil fuel reserves, and ease the global food crisis, as well as reduce environmentalpollution. As the most aboundant renewable organic carbon source, cellulose has receivedmuch attention in recent years. However, the efficient conversion of cellulose into liquid fuelsand basic chemicals is vital to effective utilization of cellulose resources.In this thesis, we have mainly studied on the degradation of cellulose into glucose and/or5-hydroxymethylfurfural （HMF） in the presence of metallic Lewis acids or inorganic-organicheteropoly solid acid in ionic liquid. The relative research contents are shown as follows.（1） Firstly, six methylimidazolium-based ionic liquids with different ions weresynthesized and their structures have also been characterized by NMR and FT-IR. We hadconducted the dissolution experiments by dissolving the cellulose in different ionic liquids, aswell as its regeneration experiments. We have found the ionic liquid [BMIM]Cl is a greatsolvent for cellulose, which can dissolve cellulose by breaking its crystalline structure butwithout derivatization reaction.（2） Next, we have studied the degradation of cellulose catalyzaed by metallic Lewisacids in the media of [BMIM]Cl. HMF has been obtained as the main product up to59.2%yield from the cellulose catalyzed by CrCl₃·6H₂O （5mol%） and FeCl₃（5mol%） in theabsence of water, after conducting the reaction for8h at120℃, and the ionic liquid can berecyeled by flash column chromatography on silica gel. The reaction conditions have beenoptimized by modifying several influencing factors, such as reaction temperature, reactiontime, catalyst loading and the combination of different metallic Lewis acids. On the otherhand, reducing sugars contaning glucose have been generated as the main products in stead ofHMF when the reactions were conducted in the appropriate amount of water. And therelatively optimized reaction conditions were described as follows. Glucose and the totalreducing sugar were formed in39.0%and70.0%yield, respectively, from cellulose catalyzedby FeCl₃（12mol%） for6h at130℃in the presence of10equivalent of H₂O, and the ionicliquid can be recycled by the same method above. Further more, cellulose could behydrolyzed into glucose and total reducing sugar by utilizing AlCl₃as catalyst under theidentical reaction conditions, in25.0%and72.0%yield, respectively, and the conversion ofcellulose was as high as99.0%.（3） In order to inhibit the formation of humins, one of the main byproducts generatedfrom polycondensation of sugars and HMF, the inorganic-organic hybrid solid acid([MIMPS]₃PW₁₂O₄₀) has been selected as the catalyst. After investigating the influencefactors, including reaction temperature, reaction time, catalyst loadings, water amounts and adding methods of water, we have determined an optimized reaction conditions. The yield ofglucose and total reducing sugar were41.0%and65.0%, respectively, when the reaction wascatalyzed by [MIMPS]₃PW₁₂O₄₀（0.7mol%） in the presence of15equivalent of H₂O at140℃. The selectivity of glucoae in the total reducing sugars was improved to63.1%, andnearly no humins have been formed during the reaction.（5） Finally, we had explored the reaction system catalyzed by [MIMPS]₃PW₁₂O₄₀inwater instead of ionic liquid. The optimized reaction conditions have been found, in that thereaction temperature was180℃, and the catalyst loading was5.8mol%, andm（Cellulose）:m（H₂O） was1:75, the yield of glucose and total reducing sugar were21.0%and34.0%, respectively.In a word, Lewis acids and organic-inorganic solid acid were found as effective catalyststo promote the conversion of cellulose, which provides a new method to transform celluloseinto platform chemicals.