Abstract Fast pyrolysis of water-insoluble (W-I) tannins—mainly composed of condensed tannins—obtained from Pinus radiata bark methanol-water extraction was carried out in pursuit of a renewable source of high-value chemicals, in particular catechols. Micropyrolysis in an isothermal furnace unit (Py-GC–MS/FID) was performed between 450–600 °C. Catechin and W-I tannins were compared to establish thermal degradation behavior between this fraction and its representative monomer constituent. Additionally, W-I tannins were compared with typical sources of renewable phenols such as pine bark and organosolv-lignin in order to highlight its potential. Bench-scale experiments of W-I tannins were performed in a fluidized bed reactor between 400–600 °C to provide information related to yield and concentration of catechols. The Py-GC–MS/FID results showed that W-I tannins are prolific of catechol and 4-methylcatechol, similar to their most abundant monomer constituent catechin. However, W-I tannins are not only composed of condensed tannins and some substituted polycyclic aromatic hydrocarbons, triterpenes and carbohydrate-derived compounds were detected. The comparison of pyrolysis products among the renewable sources of phenols showed that W-I tannins yielded the highest relative content of catechols while guaiacols and carbohydrate-derived compounds predominated in the composition of lignin and bark products, respectively. The optimal pyrolysis-oil yield for bench scale assays (37 wt%) was found at 550 °C and maximum yield of both catechol (4.4 wt%) and 4-methylcatechol (2.3 wt%) were also obtained at 550 °C.

中文翻译：

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松树皮中单宁的快速热解作为儿茶酚的可再生来源

摘要 从辐射松树皮甲醇-水提取物中提取的水不溶性 (WI) 单宁（主要由缩合单宁组成）的快速热解是为了寻求高价值化学品的可再生来源，特别是儿茶酚。等温炉装置 (Py-GC-MS/FID) 中的微热解在 450-600 °C 之间进行。将儿茶素和 WI 单宁进行比较，以确定该部分与其代表性单体成分之间的热降解行为。此外，将 WI 单宁与典型的可再生酚类来源（如松树皮和有机溶剂-木质素）进行了比较，以突出其潜力。在 400-600 °C 之间的流化床反应器中进行 WI 单宁的实验室规模实验，以提供与儿茶酚的产量和浓度相关的信息。Py-GC-MS/FID 结果表明，WI 单宁富含儿茶酚和 4-甲基儿茶酚，类似于它们最丰富的单体成分儿茶素。然而，WI单宁不仅由缩合单宁组成，还检测到一些取代的多环芳烃、三萜和碳水化合物衍生化合物。酚类可再生资源中热解产物的比较表明，WI单宁产生的儿茶酚相对含量最高，而愈创木酚和碳水化合物衍生的化合物分别在木质素和树皮产品的组成中占主导地位。在 550 °C 下发现了实验室规模测定的最佳热解油产量 (37 wt%)，在 550 °C 下也获得了儿茶酚 (4.4 wt%) 和 4-甲基儿茶酚 (2.3 wt%) 的最大产量。