Enhanced Levulinic Acid Production from Cellulose by Combined Brønsted Hydrothermal Carbon and Lewis Acid Catalysts
2019
Boonyakarn, Tat | Wataniyakul, Piyaporn | Boonnoun, Panatpong | Quitain, Armando T. | Kida, Tetsuya | Sasaki, Mitsuru | Laosiripojana, Navadol | Jongsomjit, Bunjerd | Shotipruk, Artiwan
This study presents a synergistic catalytic system using the combination of Brønsted hydrothermal carbon-based acid (HTCG-SO₃H) and Lewis acid catalysts for one-pot conversion of cellulose to levulinic acid (LA). Chromium chloride (CrCl₃), among a number of other Lewis acidic metal chlorides, was found to give the highest LA yields, and was therefore used in combination with the HTCG-SO₃H, for cellulose conversion to LA. With the appropriate amount of HTCG-SO₃H, the formation of side products could be reduced, resulting in improved selectivity of LA. Compared with that obtained by CrCl₃ alone, at 5 wt % HTCG-SO₃H, 0.015 M CrCl₃, 200 °C and 5 min reaction time, the LA yield was considerably enhanced from 30 wt % to 40 wt %. Since HTCG-SO₃H is a heterogeneous catalyst that can be easily prepared from biomass at moderate temperature, its use in such combined catalyst system offers economic and environmental benefits, thus making large-scale implementation of such process potentially feasible.
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