The structure–reactivity relationship in fast pyrolysis of lignin for monomeric phenolic compounds was studied on seven lignins from hardwood, softwood, and grass. The distribution of elements, functional groups, phenylpropane units, and interunit linkage bonds varied greatly across the lignins. Lignins from hardwood and grass prepared with mild conditions presented more C–O linkages. Pyrolysis–gas chromatography/mass spectrometry showed that the cleavage of unstable C–O linkages dominated the pyrolysis reaction at low temperatures, and the total yields of monomers peaked at 700 °C for most lignins. 4-Vinylphenol produced from acid extracted corn stalk lignin reached up to 4.77 wt % at 700 °C. Pyrolysis of grass lignins and woody lignins, which had more unstable C–O linkages, exhibited higher total yields of monomers. The pyrolysis behavior of lignin at low temperatures is closely related to its structural characteristics. Pyrolyzed at 500 °C, the total yields of monomeric aromatics were highly linearly correlated with the frequencies of C–O linkages (R² = 0.86). This work demonstrates the significance of selecting the right lignin for producing monomeric aromatic compounds.

中文翻译：

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木质素快速热解成单体酚类化合物的结构-反应关系

研究了木质素，软木和草中的七个木质素对木质素快速热解成单体酚类化合物的结构-反应关系。元素，官能团，苯丙烷单元和单元间连接键的分布在整个木质素中变化很大。在温和条件下从硬木和草中提取的木质素表现出更多的C-O键。热解-气相色谱/质谱表明，不稳定的C-O键的裂解在低温下主导热解反应，大多数木质素的单体总产率在700°C达到峰值。由酸提取的玉米秸秆木质素产生的4-乙烯基苯酚在700°C下达到4.77 wt％。草木质素和木质木质素的热解（具有更不稳定的C-O键）表现出较高的单体总收率。木质素在低温下的热解行为与其结构特征密切相关。在500°C的温度下进行热解，单体芳族化合物的总收率与C–O键的频率高度线性相关（R ²＝ 0.86）。这项工作证明了选择合适的木质素来生产单体芳族化合物的重要性。