枫木木质素热解自由基演变规律研究

STUDY ON RADICAL EVOLUTION DURING MAPLE LIGNIN PYROLYSIS

采用电子顺磁共振波谱仪(EPR)研究枫木木质素热解自由基的演变规律。实验结果表明:枫木木质素热解自由基演变过程分为3个阶段:温度低于450℃时,以自由基引发反应为主,同时液体产率在450℃达到最大;温度处于450~550℃之间时为自由基增长阶段,其自旋浓度在550℃时急剧升至276.99×10^(17)spin/g;温度高于600℃时,自由基增速放缓。此外,通过构建回归方程描述温度、氢碳比(H/C)、石墨化程度与自由基含量的耦合变化趋势,可为揭示木质素微观热解机理提供新思路。

Radical evolution during maple lignin pyrolysis is monitored by the electron paramagnetic resonance spectroscopy(EPR).Results showed that maple lignin pyrolysis radicals can be divided into three stages:the radical initiation stage below 450 ℃ in which the yield of liquid reaches the highest;the radical propagation stage between 450 ℃ and 550 ℃ in which the radical concentration increases sharply to 276.99×10^(17)spin/g at 550 ℃;the radical stabilization stage above 600 ℃. Furthermore, coupling change trend between temperature, hydrogen/carbon ratio,graphitization degree and radical concentration are separately well described by constructing regression equations,which provided a new idea to reveal the microscopic pyrolysis mechanism of lignin.