Evolution Of Hydrogen Bonds Matrix During Cellulose Pyrolysis Based On [Bmim]Cl Regeneration

Biomass pyrolysis is a promising technology to produce alternative liquid fuel in the near future. Cellulose, the most portion in lignocellulose material, with hemicellulose and lignin are the three main components in lignocellulose material, with proportions about 35-50 wt%, 25-30 wt% and 15-30 wt%. Cellulose is a linear macromolecules composed of glucopyranose D- anhydride(1-5) as the basic unit, connecting with each other by ?(1-4) glycosidic bonds. Many papers have been published about the characteristics and mechanism of cellulose pyrolysis, and most of which were based on commercial microcrystalline cellulose, such as PH101 with a certain crystallinity and degree of polymerization. However, cellulose in the natural biomass has various ultrastructure. Therefore, the effect of crystallinity on pyrolysis characteristics of cellulose and evolution of hydrogen bonds matrix during cellulose pyrolysis is of great significance.Firstly, the ionic liquid has been prepared in the lab. The cellulose of PH101 was dissolved in the heated [Bmim]Cl. Subsequently the regenerated cellulose sample was obtained by water injection. All samples of ionic liquid and cellulose had been characterized. The molecular structure of [Bmim]Cl was identified by NMR. Then XRD was used to determine the crystallinity of both raw and regenerated cellulose. SEM analysis was used to obtain the morphology features.Secondly, the effect of crystallinity on pyrolysis characteristics of cellulose has been investigated. Thermogravimetric(TG) was used to determine the thermal stability of different cellulose samples. The effect of crystallinity on pyrolysis characteristics of cellulose was also obtained by analyzing of the pyrolysis products from the cellulose with different degree of crystallinity. Py-GC/MS was applied to investigated the pyrolysis characteristic and the results showed cellulose with lower degree of crystallinity has lower levoglucosan yield but higher yield for small molecule components.Finally, the evolution of hydrogen bonds matrix during cellulose pyrolysis was studied. Behaviors of different kinds of OH and chemical bonds in cellulose has been experimentally investigated with the assistant of in-situ diffuse reflectance FTIR(DRIFT) technique, as the condition of heating up to 420? from room temperature(30?). This analysis can eliminate the effect of water on OH and hydrogen bonds by absent of KBr. The changes of cellulose structure especially crystallinity has be demonstrated by analyzing the IR spectra of cellulose at different temperatures. The IR bands intensity of free OH groups shows increasing trend, OH groups formed intramolecular hydrogen bonds has little change, OH groups associated with intermolecular hydrogen bonds decline when the cellulose heated. The caystallitiy of cellulose would decrease and it's the structure of cellulose would change dramatically beyond 240? when the cellulose is heated. The results also elucidate that intensity of DRIFT spectra bands associated with specific hydroxyl groups, glycosidic bonds can be calculated and indicate details as cellulose is heated. Intensity of bands at 894 cm-1 similar to the band at 1161 cm-1 except the former only rise to 270? compared to the latter to 300?. The result proved that destroy of glycoside ring may probably happen before the cleavage of glycosidic bond during cellulose pyrolysis.