Lignin, which accounts for nearly 15 - 30 wt% of all lignocellulosic biomass, is the largest source of naturally obtainable phenolic and aromatic hydrocarbons. The selective conversion of lignin remains an elusive challenge for researchers due to the starting material's heterogeneous nature. Therefore, the growing focus is on transforming key structural units in lignin to value-added products and chemicals. Solvolytic depolymerization in alcohols, such as methanol (MeOH) and ethanol (EtOH), effectively breaks down lignin into monomeric phenols. Our results demonstrate that it is possible to overcome the inherent limitations of batch reactors by carrying out the solvolytic deconstruction in flow-through reactors as they allow for the continuous removal and rapid cooling of the products. Flow-through reactors help mitigate repolymerization reactions and favor higher liquid product yields, which is vital for realistic scale up. This work investigates the effects of various reaction parameters, such as temperature, reaction time, and phase of solvent on the distribution and yield of lignin-derived products. p-Coumaric acid and ferulic acid were obtained as primary monomers at very high selectivity (&gt; 95%) among all monomers at all tested reaction conditions. A maximum monomeric yield of 14.45 wt% was obtained at 250 °C, 85 bar, EtOH. The potential of flow-through solvolytic deconstruction as a pretreatment technique to enhance phenolic monomers yield through fast pyrolysis was also studied. In addition to the increased yield of phenolic monomers (21.8 wt% vs 10.2 wt%), char formation during pyrolysis was also substantially decreased (26.3 wt% vs. 40.95 wt%) under optimized conditions.

Solvolytic deconstruction of corn stover lignin in flow-through reactors

ACS Spring Meeting 2021

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