复合碱定向解聚绿竹碱木质素制备酚类化合物的研究

Preparation of Phenolic Compounds by Selective Depolymerization of Alkali Lignin from Sinocalamus Oldhami Using Composite Alkali

中文关键词:  木质素  复合碱  水热降解  酚羟基  酚类化合物

Key Words:lignin  composite alkali  hydrothermal degradation  phenolic hydroxyl group  phenolic compound

中文摘要:

      以绿竹碱木质素为原料，探究了不同碱催化剂降解木质素对酚类产物的影响。结果表明，复合碱催化剂在温和的水热体系中可实现对木质素的高效降解，其中，由NaOH和亲核试剂Na₂SO₃组成的复合碱降解效果最优，木质素降解率（83.1±1.2）%和酚类化合物的相对含量（86.85%）最高，酚羟基含量相对于空白组提高了约244%；傅里叶变换红外光谱仪（FT-IR）、凝胶渗透色谱仪（GPC）和全二维气相色谱-高分辨飞行时间质谱联用仪（GC-MS）的分析结果表明，在复合碱体系中，NaOH和Na₂SO₃的协同作用可有效断裂木质素结构中的C—O键，使木质素发生定向解聚，并生成一系列低分子质量（<1000）的小分子化合物；其中，酚类产物主要包括苯酚、2-甲氧基-苯酚和4-乙基-苯酚等。

Abstract:

      The production of phenolic compounds during lignin depolymerization using different alkaline catalysts was investigated by choosing Sinocalamus oldhami alkali lignin as raw material. The experimental results showed that the composite alkali systems could effectively depolymerize the lignin under a mild hydrothermal condition， in which the composite alkali system comprising sodium hydroxide and sodium sulfite exhibited the highest efficiency of lignin degradation （83.1±1.2） % and the yield of phenolic compounds （86.85%）. Compared with the control group， the phenolic hydroxyl content increased by approximately 244%. The results of FT-IR， GPC and GC-MS indicated that the synergistic effect of NaOH and Na₂SO₃ in the composite alkali system could effectively cleave the C—O bonds in lignin， resulting in the selective depolymerization of ligin to produce a series of small molecule compounds with low molecular weight （<1000）， among which the phenolic compounds mainly included phenol， 2-methoxy-phenol， and 4-ethyl-phenol， etc.