The effects of combining guaiacol and syringol on their pyrolysis
The effects of combining guaiacol and syringol on their pyrolysis
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DOI：
10.1515/hf.2011.165
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发表时间：
2012-03-01
期刊：
影响因子：
2.4
通讯作者：
Saka, Shiro
中科院分区：
文献类型：
--
作者：
Asmadi, Mohd;Kawamoto, Haruo;Saka, Shiro
在热解反应器（N-2/600 ° C/40-600 s）中研究愈创木酚/姜子酚混合物的热解，以了解硬木木质素中芳香核的反应性。通过与纯愈创木酚或姜子油的结果进行比较，在早期热解过程中观察到它们的组合的显着效果：炭化和气体形成显着抑制。焦油馏分（甲醇可溶性）的产率增加的组合，但GC/MS检测的低分子量的产品的含量显着降低，在这些馏分中，特别是儿茶酚型化合物减少，这是通过O-CH 3均裂反应和随后的氢原子捐赠形成的。这些观察结果在分子水平上进行了讨论。抑制炭化反应，可以作为一个强的氢供体，将增加自由基偶联反应的O-CH 3均裂产物的概率，而不是邻苯二酚和连苯三酚及其衍生物的形成。后者是气体形成的重要中间体，尤其是对于CO。基于这些证据，提出了一个假设，根据该假设，碳化过程中的聚芳构化激活了愈创木酚和丁香酚的热解反应。
Pyrolysis of guaiacol/syringol mixtures was studied in an ampoule reactor (N-2/600 degrees C/40-600 s) to understand the reactivities of the aromatic nuclei in hardwood lignins. By comparing the results with those of pure guaiacol or syringol, significant effects of their combination were observed during early stage pyrolysis: charring and gas formation were markedly suppressed. Yields for the tar fractions (MeOH-soluble) were increased by combination but the contents of GC/MS-detectable products with low molecular weight were dramatically decreased in these fractions, especially catechol-type compounds diminished, which are formed through the O-CH3 homolysis reaction and subsequent donation of hydrogen atoms. These observations are discussed at the molecular level. Inhibition of the charring reaction, which can act as a strong hydrogen donor, would increase the probability of radical coupling reactions of the O-CH3 homolysis products instead of the formation of catechol and pyrogallol and their derivatives. The latter compounds are important intermediates for gas formation, especially for CO. Based on these lines of evidence, a hypothesis is proposed according to which polyaromatization during carbonization activates the pyrolytic reactions of guaiacol and syringol.