(215d) Green Chemical Conversion of Cellulose into Soluble Sugars and 5-Hydroxymethylfurfural (HMF) Using Ionic Liquids

An ionic liquid-based chemical hydrolysis strategy was developed to obtain high-yielding soluble sugars and 5-hydroxymethylfurfural (HMF), a promising platform chemical derived from cellulose. The efficiency of two biomass conversion technologies, dilute acid hydrolysis and dissolution in ionic liquids (ILs), are compared in terms of delignification, saccrification efficiency and saccharide yields with crystalline cellulose serving as a model biomass. Several ILs such as 1-ethyl-3-methylimidazolium chloride [EMIM], 1-butyl-3-methylimidazolium chloride [BMIM], 1-ethyl-3-methylimidazolium chloride aluminum chloride [EMIM] AlCl₃ were tried and analyzed for their conversion efficiency and selectivity for various products such as glucose, fructose, HMF, and formic acid etc. Initial ILs dissolution and subsequent acid hydrolysis improved the dissolution and release of total sugars from cellulose. The amount of mineral acid load was also reduced considerably by initial ILs dissolution of cellulose. [EMIM] treatment on the long fibers of cellulose had no significant effect on the cellulose morphology as evident by scanning electron microscopy (SEM), and optical microscopy analysis (OM). Acid catalyzed hydrolysis and dissolution in ILs resulted in higher conversion of sugars which was evident by Benedict’s test’, analysis for reducing sugars. Conversion of various products was also analyzed by Fourier Transform-infrared spectroscopy (FT-IR). The condition including the ratio of Ils to cellulose, temperature and time for cellulose conversion was optimized. This ionic liquid-based hydrolysis strategy showed the great potential to produce soluble sugars and HMF from cellulose.