绿液预处理过程中杨木木质素结构的变化

以绿液(Na₂S和Na₂CO₃)对杨木进行预处理,研究了预处理条件对木质素脱除的影响,并用碱性硝基苯氧化表征预处理后木质素化学结构特征的变化。结果表明:杨木原料木质素的碱性硝基苯氧化产物的总得率为2.61 mmol/g,其木质素非缩合部分紫丁香基结构的硝基苯氧化降解产物与愈疮木基摩尔比n(S+SA)/n(V+VA)为2.0; 随着预处理H-因子的升高和用碱量的增加,杨木浆料的木质素脱除率上升,n(S+SA)/n(V+VA)下降; 杨木浆料残余木质素的缩合程度随着木质素脱除率的增加而增大,且紫丁香基丙烷结构比愈疮木基丙烷结构在绿液预处理过程中更容易断裂。

Structural changes of poplar lignin in the process of green liquor pretreatment

Green liquor(Na₂S and Na₂CO₃)was used as a pretreating regent for poplar wood, and the effects of green liquor pretreatment on lignin removal, and lignin structure were investigated in this paper. The residual lignin in the pretreated poplar was characterized by alkaline nitrobenzene oxidation(NBO). The results showed that the total NBO products yield of poplar lignin was 2.61 mmol/g, and the molar ratio of n(S+SA)/n(V+VA)in non-condensed lignin was 2.0. With the increasing of TTA charge and H-factor of green liquor pretreatment, lignin was effectively removed, and the yields of total NBO products, and the molar ratio of n(S+SA)/n(V+VA)decreased. The condensation degree of residual lignin in pretreated solid increased with the lignin removal, and the syringyl lignin was more degradable as compared to guaiacyl type in green liquor pretreatment.