(424d) Catalytic Fast Pyrolysis of Lignin Recovered from Hot-Water Extract of Electron-Beam-Irradiated Sugar Maple for the Production of Low Molecular Weight Phenolic Compounds
Thermochemical degradation of lignin at a high temperature in a controlled atmosphere (pyrolysis) is a promising technique to replace fossil fuels for the production of low molecular weight (LMW) phenolic chemicals. Conventionally, however, pyrolysis of lignocellulosic (LC) materials including current sulfur-containing technical lignins (e.g. kraft, lignosulfonates) is plagued by low yields, poor selectivity to desired products, and catalyst deactivation. These issues must be addressed for lignin pyrolysis to become a viable industrial process. It has been shown that the nature of the material being pyrolyzed has a large impact on the resulting yield of phenolic products. Furthermore, it has been shown that biorefinery lignins may have a more favorable structure and composition (e.g. increased purity and lower polydispersity) for the production of high-value products as compared to kraft lignin. In this work, results of pyrolysis and catalytic upgrading of novel biorefinery lignins are presented to better understand the effects of lignin structure and composition on pyrolysis products. Electron beam irradiation (EBI) has been shown to increase mass removal during autohydrolysis-based pre-extraction (hot-water extraction). Lignin recovered from hot-water extraction of native and EBI (100-1000 KGy) sugar maple (precipitation at pH 2 followed by centrifugation) was characterized (purity, free phenolic hydroxyl group content, molecular weight distribution, S/G ratio, β-O-4 content). Thermal degradation characteristics of these lignins were analyzed by TGA. Fast pyrolysis (550°C) was performed with subsequent catalytic defunctionalization (upgrading) with various zeolite catalysts (ZSM-5, Y, and Beta) to produce a more uniform stream of LMW phenolic compounds; GC-detectable pyrolysis products were analyzed by GC-MS. Based on results, the effect of EBI on lignin structure and properties and the repercussions for catalytic fast pyrolysis will be assessed.