Decomposition characteristics of softwood lignophenol under hydrothermal conditions

Lignophenol is a novel lignin-based functional polymer. Hydrothermal decomposition of ligno-p-cresol derived from softwood (Douglas fir) was studied from 300 to 400 °C as a candidate technology for modification of the molecular structure and the recovery of monophenols. Ligno-p-cresol was promptly depolymerized probably by hydrolysis of aryl ether linkages and the half was converted to ether-soluble compounds at 300 °C for 10 min. With increasing temperature and reaction time, the yields of char and gas were increased, indicating the acceleration of carbonization and decomposition of monophenols. The monophenols obtained were mainly p-cresol and guaiacol. Their yields only exceed 10% at 365 °C and 60 min probably due to the inefficient pyrolysis of 1,1-bis aryl structures.