亚临界水中杉木碱木质素的解聚特性分析

Depolymerization Characteristics of Cunninghamialanceolata Alkali Lignin in Subcritical Water

利用间歇式高压反应釜在250~350℃的亚临界水中进行杉木碱木质素的水热解聚反应。通过GC/MS的定性、定量分析以及元素分析和FT-IR,分析反应液相和固相产物的组成与结构变化,探究了不同温度下碱木质素水热解聚的反应特性。结果表明,碱木质素水热解聚反应残渣率在325℃时最低,为18.66%。碱木质素在亚临界水中解聚所得的液相产物中酚类化合物GC含量均在80%以上,且随反应温度的升高,酚类化合物种类增加,总酚含量提高。酚类产物中愈创木酚的含量最高,其质量分数在325℃时达最高17.71 mg/g。随着反应温度升高,在一定程度上木质素脱氢脱氧,含碳量增加。在325℃时碳基转化率和能量转化率均最高,分别为79.18%和79.95%。在温度低于325℃时,水热焦的化学结构与木质素相似,达到350℃时,木质素严重缩合炭化。

Hydrothermal depolymerization of Cunninghamialanceolata alkali lignin were conducted in a batch autoclave at temperatures of 250-350 ℃. The components and characteristics of hydrothermal degraded liquid products and hydrochar were investigated by gas chromatography with mass spectrometry（ GC / MS）,elemental analyzer and Fourier transforms infrared spectroscopy（ FT-IR）. The results showed that the least residue（ 18. 66 %） was collected at 325 ℃. In addition,the relative content of phenols in liquid products was above 80 %,and the types and contents of phenols were both increased with the rise of temperature. Guaiacol was the dominant phenol component,represented 17. 71 mg / g at 325 ℃. With the increase of reaction temperature,reductions of hydrogen and oxygen contents were observed,while the carbon content increased. The optimum carbon and energy conversion rates at 325 ℃ were 79. 18 % and 79. 95 %,respectively. The chemical structures of hydrochars were similar to alkali lignin at temperatures below 325 ℃. However,a serious carbonization of lignin was observed when the temperature was over350 ℃.