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分别从杨木硫酸盐制浆黑液和玉米芯酸水解残渣中分离提纯木素,通过元素分析、红外、31P-NMR等方法对两种木素进行了结构的表征与对比;对两种木素进行了不同反应温度(220~340℃)下的亚临界水热转化实验,主要产物通过GC-MS和GC进行了定性与定量分析。结果发现:两种木素的水热转化产物主要为酚类化合物,酸水解残渣木素水热转化产物苯酚、愈疮木酚和4-乙基愈疮木酚在280~310℃时得率达到最高,分别为12.6 mg·g-1、7.5mg·g-1和10.9 mg·g-1;相比而言,黑液碱木素水热转化主要产物得率稍低,且需更高的反应温度达到极大值。两种木素水热转化特性的差异可归因于其化学结构的不同。
The lignin was separated and purified from poplar kraft black liquor and corncob acid hydrolyzate, respectively. The structure and structure of the two lignins were characterized by elemental analysis, infrared and 31P-NMR. Subcritical hydrothermal conversion experiments were carried out at various reaction temperatures (220-340 ℃). The main products were qualitatively and quantitatively analyzed by GC-MS and GC. The results showed that the hydrothermal conversion products of the two lignins were mainly phenolic compounds. The yields of phenol, guaiacol and 4-ethylguiculol at 280 ~ 310 ℃ were the best. Reaching the highest levels of 12.6 mg · g-1, 7.5 mg · g-1 and 10.9 mg · g-1, respectively; in contrast, the yields of the major products of hydrothermal conversion of black liquor alkali lignin were slightly lower and higher The reaction temperature reached its maximum. The differences in the hydrothermal conversion characteristics of the two lignins can be attributed to their different chemical structures.