Laboratório de Química Orgânica, Departamento de Química, Universidade Federal do Espírito Santo (UFES), Avenida Fernando Ferrari, 514, Goiabeiras, Vitória, ES 29075-910, Brazil.
Grupo de Química Supramolecular e Biomimética (GQSB), Departamento de Química, Universidade Federal de Viçosa, Viçosa, MG 36570-900, Brazil.
Waste Manag. 2021 May 1;126:274-282. doi: 10.1016/j.wasman.2021.03.016. Epub 2021 Mar 27.
Levoglucosan (LGA) is a promising chemical platform derived from the pyrolysis of biomass that offers access to a variety of value-added products. We report an efficient route to produce LGA via the pretreatment of biomass with niobium compounds (oxalate, chloride and oxide) followed by fast pyrolysis coupled with gas chromatography-mass spectrometry (Py-GC-MS) at temperatures of 350-600 °C. Catalytic pretreatment reduces the quantity of lignin in the biomass, concentrates the cellulose and enhance LGA formation during fast pyrolysis. The pretreatment also removes alkaline metals, preventing competitive side reactions. The effect of several parameters such as catalyst weight, time, temperature, and solvent, with the optimal pretreatment conditions determined to be 3 (wt.%) niobium oxalate for 1 h at 23 °C in water. Pretreatment increased the LGA yields by 6.40-fold for sugarcane bagasse, 4.15-fold for elephant grass, 4.13-fold for rice husk, 2.86-fold for coffee husk, and 1.86-fold for coconut husk as compared to the raw biomasses. These results indicate that biomass pretreatment using niobium derivates prior fast pyrolysis can be a promising technique for biomass thermochemical conversion in LGA and others important pyrolytic products.
左旋葡聚糖（LGA）是一种有前途的化学平台，源自生物质热解，可获得多种增值产品。我们报告了一种通过用铌化合物（草酸盐、氯化物和氧化物）预处理生物质，然后在 350-600°C 的温度下进行快速热解并结合气相色谱-质谱（Py-GC-MS）来生产 LGA 的有效途径。催化预处理减少了生物质中的木质素含量，浓缩了纤维素，并在快速热解过程中促进了 LGA 的形成。预处理还去除了碱金属，防止了竞争性副反应。研究了催化剂重量、时间、温度和溶剂等多个参数的影响，确定最佳预处理条件为 3（wt.%）草酸铌在 23°C 下于水中预处理 1 小时。与原始生物质相比，预处理使甘蔗渣、象草、稻壳、咖啡壳和椰子壳的 LGA 产率分别提高了 6.40 倍、4.15 倍、4.13 倍、2.86 倍和 1.86 倍。这些结果表明，在快速热解之前使用铌衍生物对生物质进行预处理可能是一种有前途的生物质热化学转化为 LGA 和其他重要热解产物的技术。
