蔗渣碱木素液化制备酚类化合物

Production of Phenolic Chemicals via Liquefaction of Alkali Lignin from Bagasse

为了提高蔗渣碱木素的利用价值,以硅酸铝为催化剂催化碱木素的液化过程来制备酚类化合物.对硅酸铝用量、加热时间、加热温度、溶剂体积与溶质质量比等工艺条件进行了优化,确定了最优条件为:硅酸铝用量为绝干碱木素质量的4%,加热时间1h,加热温度270℃,溶剂(丙三醇)体积与溶质(蔗渣碱木素)质量比为6mL/g,此条件下酚类化合物的总得率为54.10%(相对于碱木素干重),所得酚类产物的主要成分是2,6-二甲氧基苯酚、2-甲氧基苯酚和苯酚.采用红外光谱和核磁共振氢谱检测碱木素反应前后的官能团结构,发现:在硅酸铝的催化下,加热温度达270℃时,木素结构中的脂肪族侧链与苯环分离,大量β位的醚键会因为高温和酸的共同作用而发生断裂,少量α位的醚键同样会发生断裂并随着脂肪族侧链的断裂而生成苯酚.

In order to increase the utilization value of alkali lignin from bagasse,aluminium silicate was chosen as the catalyst to produce phenolic chemicals from the lignin via a liquefaction process.The reaction conditions including aluminium silicate dosage,heating time,heating temperature and liquid-solid（glycerol-bagasse alkali lignin） ratio were then optimized as follows： an aluminium silicate dosage of 4%（based on the dry bagasse alkali lignin）,a heating duration of 1 h,a heating temperature of 270℃ and a liquid-solid ratio of 6 mL/g（based on the dry bagasse alkali lignin）.In these conditions,phenolic chemicals mainly containing 2,6-dimethoxy-phenol,2-methoxy-phenol and phenol were produced,with a total yield of 54.10%.Moreover,the structures of functional groups of the alkali lignin before and after the liquefaction were analyzed by means of FT-IR and 1H NMR.The results show that,when the heating temperature reaches 270 ℃,the propane units of the phenylpropane separate from benzene units in the presence of aluminium silicate,and the β-ether lingkages（β-O-4） break due to high temperature and the existence of acid.At the same time,few α-ether lingkages（α-O-4） break to produce phenols following the separation of propane units.