Some ionic liquids (ILs) have a high ability to deconstruct recalcitrant structure of cellulose (i.e., cellulose pretreatment), and increase subsequent hydrolysis efficiency. However, a major problem on using ILs for cellulose pretreatment is their high cost. High loading of cellulose in the IL pretreatment process is potentially a key technology of cellulose conversion to glucose in biorefining. In this work, accessibilities of cellulose pretreated by [Emim][OAc], as the most representative IL for lignocellulose pretreatment, with a wide cellulose loading range (5–50 mol%) and its relationship with hydrolytic reactivity are comprehensively elucidated. We discovered for the first time faster glucose conversion at higher cellulose loading. When microcrystalline cellulose was pretreated with 6 times higher loading amount (24 wt%) than the conventional condition of 5 wt%, the subsequent hydrolytic reaction catalyzed by acid was enhanced 1.6-fold. This enhancement was well explained by the increase of accessibility estimated from crystallinity and specific surface area. In order to expand the concept that higher loading amount can lead to higher hydrolytic reactivity, we also employed bagasse as lignocellulose biomass and performed the pretreatment by using the same IL. It was revealed that even in bagasse where cellulose is encapsulated in hemicellulose-lignin matrix, the pretreatment efficiency was higher at higher loading to a certain extent. The optimized loading amount and the degree of enhancement were similar to those in microcrystalline cellulose.<br/>This research was promoted by COI program “Construction of next-generation Infrastructure using innovative materials-Realization of a safe and secure society that can coexist with the Earth for centuries” supported by MEXT and JST.

Efficient ionic liquid pretreatment of cellulose at higher loading

254th National Meeting (2017)

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