Enriching high-value chemicals from the pyrolysis of agricultural and forestry waste is an efficient way to achieve sustainable development and large-scale application of biomass pyrolysis. Phenols, as important chemical raw materials, spices and food additives, have attracted widespread attention. Herein, a novel technical route of torrefaction pretreatment combined with fractional condensation in pyrolysis loop was proposed to enrich the phenols in liquid products. In this study, the enrichment of phenols from the pyrolysis loop of walnut shell under the combination of torrefaction and fractional condensation was explored using a fixed-bed pyrolysis reactor equipped with a three-stage condensation system. Simultaneously, the effects of torrefaction on feedstocks were investigated through a thermogravimetric analyzer based on the characteristics of feedstocks. The results showed that the torrefaction and pyrolysis loop had a negative impact on the pyrolysis efficiency and the yield of liquid products, while the change in the condensation efficiency depended on the combined effects of torrefaction and pyrolysis loop. In addition, phenols tended to be enriched in the second condensation stage, especially phenol, o-cresol, 4-ethylphenol. Importantly, torrefaction could significantly enrich phenols in the liquid products, and the enrichment of phenols is relatively increased by 109.44% at least. Moreover, the pyrolysis loop was also beneficial to the enrichment of phenols, which was at least 90% higher than that of walnut shell. This study provided a potential route to enrich high value-added products from the pyrolysis loop of lignocellulosic biomass.

从农林废弃物热解中富集高价值化学品是实现生物质热解可持续发展和规模化应用的有效途径。酚类作为重要的化工原料、香料和食品添加剂，受到了广泛关注。在此，提出了一种新的烘焙预处理结合热解回路分馏浓缩的技术路线，以富集液体产品中的酚类。在这项研究中，使用配备三级冷凝系统的固定床热解反应器探索了在烘焙和分馏相结合的情况下胡桃壳热解回路中酚类的富集。同时，通过基于原料特性的热重分析仪研究了烘焙对原料的影响。结果表明，烘焙和热解回路对热解效率和液体产物的产率有负面影响，而冷凝效率的变化取决于烘焙和热解回路的综合作用。此外，酚类往往在第二个缩合阶段富集，尤其是苯酚、邻甲酚、4-乙基苯酚。重要的是，烘焙可以显着富集液体产品中的酚类物质，酚类物质的富集度至少相对提高了109.44%。此外，热解回路也有利于酚类的富集，比核桃壳高出至少 90%。