Reaction chemistry and phase behavior of lignin in high-temperature and supercritical water.
Decomposition of organosolve lignin in water/phenol solutions was studied in a 50 nL micro-reactor coupled with optical, Raman and infrared microscopies at temperatures up to 600 degrees C and water densities up to 1165 kg/m3. It was found that when phenol was used with {lignin+water} mixtures that a homogenous phase was formed that seemed to promote the decomposition of lignin into phenolic fragments by hydrolysis and pyrolysis. Phenol, along with the homogenous reaction conditions also inhibited re-polymerization of the phenolics and promoted oil formation. On the other hand, in the absence of phenol, lignin remained as a heterogeneous phase with water over the range of conditions studied. The homogeneous conditions and conditions for inhibiting char formation by phenol were elucidated and it was found that mixtures of phenol and lignin become homogeneous at 400-600 degrees C and high water densities of 428-683 kg/m3, corresponding to maximum pressures of 93 MPa. These results were further used to propose reaction paths.
Fang
Zhen
Z
Chinese Academy of Sciences, Biomass Group, Xishuangbanna Tropical Botanical Garden, 88 Xuefulu, Kunming, Yunnan Province 650223, China. zhenfang@xtbg.ac.cn
Sato
Takafumi
T
Smith
Richard L
RL
Inomata
Hiroshi
H
Arai
Kunio
K
Kozinski
Janusz A
JA
D008031:Lignin / Q000737:chemistry*; D019800:Phenol / Q000737:chemistry; D013696:Temperature; D014867:Water / Q000737:chemistry*
D014867:Water; D019800:Phenol; D008031:Lignin