(570aq) Development of near-Critical Water Reaction System for Utilization of Woody Lignin as Fuel and Chemical Resources

Plant biomass has been proposed to be an alternative source of petroleum-based chemical compounds. Especially, phenolic chemical compounds can be obtained from lignin by chemical depolymerization processes because lignin consists of complex aromatic polymer such as trans-p-coumaryl, coniferyl and sinapyl alcohols, etc. Phenolic chemical compounds were produced at Near-critical water (NCW). Near-critical water (NCW) is known as a good solvent for lignin depolymerization because it has a unique acid-base property without conventional non-eco-friendly chemicals such as sulfuric acid and sodium hydroxide. Organic matter like lignin can be solved in NCW and the phenolic products can be easily separated from the reaction medium. In this work, we tried to optimize the NCW depolymerization system by adjusting the processing variables such as reaction time, temperature and pressure. Moreover, phenol was used as capping agent to prevent re-polymerization of active fragment such as formaldehyde and the amount of additional phenol was optimized by changing the molar ratio between water and phenol. Alkali-lignin was used as a starting material and characterized by a Solid State 13C-NMR, FT-IR and EA (Elemental Analysis). GC-MS analysis confirmed that o-cresol, p-cresol, anisole and 4-hydroxyphathalic acid were mainly produced and they were quantitatively analyzed by HPLC.