Transformation\nof Sugar Cane Lignin into Renewable\nFuel-Range Cyclo-Alkanes: In-Situ Hydrogen Release Using Earth-Abundant\nAlCl<sub>3</sub> and Biobased Mannose Triflate Support

In\nlignin catalytic biorefining, advanced catalysts are progressively\nreplacing conventional options to enhance efficiency. This study utilizes\na sugar-based triflate (mannose triflate) and aluminum chloride (AlCl<sub>3</sub>), leveraging the in situ hydrogen release capability of propylene\nglycol to achieve lignin valorization into renewable fuels. The designed\ncatalyst, Al-OTf<sub>3</sub>-pgOH, effectively deploys triflate anions\nat low temperatures. Its properties were thoroughly investigated and\ncompared with two control catalysts, Al-pgOH and pgOH. The impacts\nof the lignin particle size, temperature, and reaction time were examined\nfor each catalyst. Al-OTf<sub>3</sub>-pgOH achieved a 98.5% lignin\nconversion with an optimal lignin particle size of 100 μm, a\nreaction temperature of 150 °C, and a reaction time of 5 h. The\nWilkinson model indicated that lignin depolymerization was third-order\nin the initial 5 h and second-order over the following 25 h. Among\nthe three catalysts, Al-OTf<sub>3</sub>-pgOH resulted in the lowest\namount of oxygenates and phenolics, and the highest yield of monocyclic\nalkanes, showing a 56.1 wt % cycloalkane yield corresponding to 79.0%\nselectivity. Notably, this is the total yield from 7-ethylcyclopentane,\n8-cyclohexyl cyclopropane, and 9-methylcyclopentane with individual\nyields of 35.5, 12.7, and 7.8 wt %, respectively. This study, therefore,\ndemonstrates that mannose triflate’s acidic catalytic sites\ncan effectively produce valuable renewable fuel hydrocarbons from\nsugarcane-derived lignin.