A novel chemical pretreatment method to accelerate bioconversion rate of renewable feedstocks

Lignocellulosic biomass is the most abundant naturally renewable organic resource for biofuels production. Due to its recalcitrance to hydrolysis, pretreatment is a crucial step prior to enzymatic hydrolysis of the feedstock. A variety of pretreatment methods have been intensively studied to achieve optimal yield without imposing significant adverse impact on the environment. Herein, we present a novel chemical pretreatment method using substituted heterocycles in an environmentally friendly way.

1-Methylimidazole is a precursor to some imidazolium-based ionic liquids. It can be used as a pretreatment agent at mild conditions, i.e. ambient temperature and pressure, for a very short period of time to obtain a substantial increase in the hydrolysis rate throughout the entire course of conversion for cellulose substrate. Furthermore, the pretreatment effectiveness of 1-methylimidazole on both untreated and steam-exploded lignocellulosic biomass including loblolly pine, switchgrass and sugarcane bagasse has been investigated and 1-methylimidazole was found to be an efficient delignifier. Remarkable rate enhancement was also observed for the non-woody lignocellulosic substrates after 1-methylimidazole pretreatment at ambient condition for short time (i.e. 5 min). The mechanism of 1-methylimidazole pretreatment is investigated through analysis of cellulose physical properties including crystallinity index, degree of polymerization, accessibility as well as lignin dissolution quantification and lignin characterization. To further optimize the novel pretreatment method, 1-methylimidazole recycling is also being investigated.