In lignin catalytic biorefining, advanced catalysts are progressively replacing conventional options to enhance efficiency. This study utilizes a sugar-based triflate (mannose triflate) and aluminum chloride (AlCl₃), leveraging the in situ hydrogen release capability of propylene glycol to achieve lignin valorization into renewable fuels. The designed catalyst, Al-OTf₃-pgOH, effectively deploys triflate anions at low temperatures. Its properties were thoroughly investigated and compared with two control catalysts, Al-pgOH and pgOH. The impacts of the lignin particle size, temperature, and reaction time were examined for each catalyst. Al-OTf₃-pgOH achieved a 98.5% lignin conversion with an optimal lignin particle size of 100 μm, a reaction temperature of 150 °C, and a reaction time of 5 h. The Wilkinson model indicated that lignin depolymerization was third-order in the initial 5 h and second-order over the following 25 h. Among the three catalysts, Al-OTf₃-pgOH resulted in the lowest amount of oxygenates and phenolics, and the highest yield of monocyclic alkanes, showing a 56.1 wt % cycloalkane yield corresponding to 79.0% selectivity. Notably, this is the total yield from 7-ethylcyclopentane, 8-cyclohexyl cyclopropane, and 9-methylcyclopentane with individual yields of 35.5, 12.7, and 7.8 wt %, respectively. This study, therefore, demonstrates that mannose triflate’s acidic catalytic sites can effectively produce valuable renewable fuel hydrocarbons from sugarcane-derived lignin.

中文翻译：

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将甘蔗木质素转化为可再生燃料范围的环烷烃：使用地球上丰富的 AlCl3 和生物基甘露糖三氟甲磺酸载体原位放氢


在木质素催化生物精炼中，先进的催化剂正在逐步取代传统选项以提高效率。本研究利用糖基三氟甲磺酸 （mannose triflate） 和氯化铝 （AlCl₃），利用丙二醇的原位氢释放能力实现木质素价值化为可再生燃料。设计的催化剂 Al-OTf_3-pgOH 可在低温下有效部署三氟磺酸阴离子。对其性质进行了深入研究，并与两种对照催化剂 Al-pgOH 和 pgOH 进行了比较。检查了每种催化剂的木质素粒径、温度和反应时间的影响。Al-OTf_3-pgOH 实现了 98.5% 的木质素转化率，最佳木质素粒径为 100 μm，反应温度为 150 °C，反应时间为 5 h。Wilkinson 模型表明，木质素解聚在最初的 5 h 为三级，在接下来的 25 h 为二阶。在三种催化剂中，Al-OTf_3-pgOH 的含氧化合物和酚类化合物含量最低，单环烷烃的产率最高，环烷烃产率为 56.1 wt，对应于 79.0% 的选择性。值得注意的是，这是 7-乙基环戊烷、8-环己基环丙烷和 9-甲基环戊烷的总产量，分别为 35.5、12.7 和 7.8 wt %。因此，这项研究表明，甘露糖三氟甲磺酸的酸性催化位点可以有效地从甘蔗衍生的木质素中产生有价值的可再生燃料碳氢化合物。