Hydrothermal liquefaction of cellulose and lignin: a new approach on the investigation of chemical reaction networks

Hydrothermal liquefaction is one of the most promising technologies to convert high moisture biomass into biofuels. However, understanding the liquefaction mechanism of different biomass fractions is still a challenge. The liquefaction of both lignin and cellulose is frequently studied, but the high diversity of biomass and processes used to generate these fractions makes the direct comparison difficult. In this work, one studies the liquefaction of lignin which has been generated in the process of lignocellulosic ethanol production employing acidic steam explosion. Results are compared with the liquefaction of commercial cellulose. The results have shown that this kind of lignin could produce higher amounts of bio-oil. Moreover, a model to quantify the contribution of the main kinds of reactions to the liquefaction mechanism was proposed. Dehydration was the main reaction observed for both raw materials, however decarboxylation plays a more relevant role in lignin liquefaction, accounting for near 37% of reactions in liquefaction pathway, whereas for cellulose it represents only 13% of reactions.