The Synthesis Of Novel SO₃H-functionalized Ionic Liquids And Their Applications In Cellulose Hydrolysis

Cellulose, a widespread renewable resource in nature, has wide scope of applications. The productsobtained from cellulose degradation, such as reducing sugar and5-hydroxymethylfurfural, are importantorganic chemical raw materials and intermediates. The conversion of cellulosic biomass directly into energymaterials and functional materials by chemical methods and modern physical technologies becomes a hotsubject. As environment-friendly reaction media, ionic liquids (ILs) have many advantages, such as lowvapor pressure, good thermal stability and regulated function. With the stronger capacity of dissolvingcellulose, ILs, as solvent and catalysts, can be used in the hydrolysis of cellulose. As a part of the NationalNature Science Foundation of China (No.21173070), a series of SO3H-functionalized ionic liquids based on2-Phenyl-2-imidazoline were synthesized and used as catalysts for the hydrolysis of cellulose. The majorcontents of the present work are as follow:1. Six kinds of novel SO3H-functionalized ionic liquids based on2-Phenyl-2-imidazoline weresynthesized. The acidity, thermal decomposition temperature and structure of the acidic ionic liquids wereinvestigated and characterized by UV-VIS, TGA and NMR.2. The acidic ionic liquids used as catalysts for the hydrolysis of cellulose in [Bmim]Cl wereinvestigated. The effect on the yield of the reducing sugar were investigated by acidity, amount of water andreaction conditions including reaction temperature and reaction time, and the possible mechanism ofcellulose hydrolysis was speculated. And the acidic ionic liquids with anions HSO￣4and Cl￣showed goodcatalytic activity on the hydrolysis of cellulose. When the hydrolysis of cellulose was catalyzed by1-propyl sulfonic acid-2-phenyl imidazoline hydrogensulfate, the TRS yield was up to85.1%in60min at100°С.3. The conversion of cellulose into carbon dots in [Bmim]Cl catalyzed by SO3H-functionalized ionicliquid was investigated, and the obtaind carbon dots showed favorable tuneable property of fluorescence.The fluorescent emission wavelength showed a red-shift with increasing reaction time. In the hydrolysisreaction, the fluorescent emission wavelength of the as-prepared carbon dots shifted from417nm to517nm when the reaction time changed from10min to80min. It was found that the tunable luminescence properties can be regulated and controlled by reation time.