Solvolysis of enzymatic hydrolysis lignin in fuel compatible solvents

Abstract

Enzymatic hydrolysis lignin (EHL), a by-product of bioethanol production, is regarded as a promising feedstock to produce chemicals and fuels, but its utilization has been limited. The solvolysis of EHL has been explored intensively in recent years and has progressed rapidly, particularly with the application of fuel-compatible solvents. This work reports EHL solvolysis at 240 °C in five solvents, i.e., dioxane, ethanol, ethyl acetate, heptane and water. Dioxane achieves the highest liquefaction degree, while ethanol yields the most monomers. In contrast, water and heptane result in inefficient liquefaction and monomer production. Simulation reveals that van der Waals and electrostatic interactions between solvents and EHL play different roles in dissolution process. Hydrogen bonds formed between the solvent and EHL facilitate the cleavage of the β-O-4 bonds, and hydrogen atom in the alkyl side chains tends to detach to form hydrogen radical, resulting in a self-supply of hydrogen atom.