木质素单体模化物的热解与产物分析

采用苯酚、邻苯二酚、愈创木酚和紫丁香酚为木质素单体模化物，利用两段裂解反应器-在线气相色谱仪（GCs）进行热解实验和产物分析，采用多色谱柱对无机气体（IGs）、C₁~C₅烃（C₁~C₅ LHs）、非芳基含氧化合物、酚和芳烃进行定量分析，以确定羟基和甲氧基对木质素热解过程中开环反应及产物分布的影响. 结果显示：羟基和甲氧基可以提高模化物的转化率，且羟基和甲氧基的存在影响芳基开环反应、芳基取代反应和重排反应间的竞争关系，使热解产物分布存在明显差异. 4种模化物热解产物主要是芳环的开环反应产物，包括IGs（质量分数为27.29%~33.56%）和C₁~C₅烃（20.46%~39.51%）. 一氧化碳产率（23.82%~29.18%）随羟基数增加而升高，随甲氧基数增加而降低；二氧化碳产率（0.19%~9.61%）随甲氧基数增加而升高. 羟基和甲氧基的存在降低了C₁~C₅烃的质量选择性，促进了烷基苯、大分子化合物和焦炭的形成.

Pyrolysis and product analysis of lignin monomer model compounds

Phenol, catechol, guaiacol and syringol, as lignin monomer model compounds, were pyrolyzed in a two-stage tubular reactor, and pyrolysis products were quantified by on-line gas chromatography (GCs). Inorganic gases (IGs), C₁~C₅ hydrocarbons (C₁~C₅ LHs), non-aryl oxygen-containing compound, phenols and aromatic hydrocarbon were quantified by GC. The purpose is to determine the effect of hydroxyl and methoxy on the ring-opening reaction of aromatic ring and product distribution during lignin pyrolysis process. Results show that hydroxyl and methoxy can improve the model compound conversion rate, and the existence of hydroxyl and methoxy affects the competition of aryl ring opening reaction, aryl substitution reaction and rearrangement reaction, leading to the obvious products distribution differences in the model compounds pyrolysis. The main products are formed from the ring-opening reaction, including IGs (mass fraction of 27.29%~33.56%) and C₁~C₅ LHs (20.46%~39.51%). The CO yield (23.82%~29.18%) is improved by hydroxyl, and reduced by methoxy. Methoxy enhances the CO₂ formation with its yield in 0.19%~9.61%. Hydroxyl and methoxy reduce the mass selectivity of C₁~ C₅ hydrocarbon, but promote the formation of alkyl benzene, macromolecular compounds and coke.