为了提高生物质乙醇木质素的反应活性, 采用水热法在四种不同碱性条件下对生物质乙醇木质素进行催化活化处理。 运用傅里叶变换红外光谱（FTIR）、 核磁共振氢谱（1H-NMR）、 凝胶色谱（GPC）和有机元素分析手段研究了生物质乙醇木质素被四种碱（NaOH, KOH, K2CO3和Na2CO3）催化活化前后木质素的化学结构以及组分变化。 FTIR结果表明生物质乙醇木质素碱经处理后, 木质素的酚羟基特征吸收峰1 375 cm-1都有明显增大趋势, 醚键振动吸收峰1 116 cm-1减弱, 1 597和1 511 cm-1处苯环骨架振动吸收峰强度变化很小; 1H-NMR分析结果表明酚羟基含量都有增大趋势, 增加顺序为: KOH>NaOH>K2CO3>Na2CO3, 其中KOH处理后的木质素酚羟基含量增加量为原木素的170%。 这由于离子半径大的钾离子更容易与木质素β—O—4醚键上的氧形成加和物, 进而发生醚键断裂反应, 生成新的酚结构衍生物。 GPC 表明生物质乙醇木质素碱处理后分子量分布向低分子区域扩展, 数均和重均分子量减小。 元素分析结果显示木质素经过水热反应处理后, C含量都有所增加, 而H和O含量则降低了, 表明木质素经水热反应处理过程中有脱羧基作用, 同时蛋白质的含量也有所降低, 提高了木质素的纯度。 这都有利于直接将木质素用于制备酚醛树脂胶黏剂。

In order to improve the reaction activity of bioethanol lignin, we investigated the activation of bioethanol lignin by a hydrothermal treatment method. Catalytic hydrothermal treatment of bioethanol lignin was performed at 180 ℃ for 3 h in the presence of alkaline solutions (NaOH, Na2CO3, KOH and K2CO3), the change in bioethanol lignin structures was studied comparatively by FTIR, 1H NMR, GPC and elemental analysis. FTIR spectra showed that after alkali hydrothermal treatment, the band at 1 375 cm-1 attributed to the phenolic hydroxyl groups increased, and the band intensity at 1 116 cm-1 attributed to the ether bond decreased. On the other hand, the band at 1 597 and 1 511 cm-1 attributed to aromatic skeletal vibration remained almost unchanged. 1H NMR spectra showed that after alkali hydrothermal treatment, the number of aromatic methoxyl is increased, and based on the increment of the content of phenolic hydroxyl, the catalytic activity can be ranked as follows: KOH>NaOH>K2CO3>Na2CO3. Especially for KOH, the increment of the content of phenolic hydroxyl was 170%, because the ion radius of potassium cation is bigger than sodium cation, so the potassium cations more easily formed cation adducts with lignin. GPC results showed that the molecular weight of alkali hydrothermal treatment lignin decreased and the molecular distribution got wider. Elemental analysis showed that hydrothermal treatment could break the interlinkage between lignin and protein, which can reduce the protein content and increase the purity of lignin, meanwhile, the content of O and H both decreased, while C fell, indicating that the bioethanol lignin had suffered a decarbonylation reaction. This is the most benefit of the lignin as a substitute for phenol.