Are fermentation products promising feedstock for high-density bio-fuel? domino reactions for upgrading aqueous acetone–butanol–ethanol mixtures

Abstract

Efficient and selective upgradation of aqueous acetone–n-butanol–ethanol (ABE) mixtures to high-density bio-fuel, especially the aviation fuel and biodiesel is extremely desirable but still remains a significant challenge. Herein, for the first time, we report an efficient strategy, in which aqueous ABE fermentation mixtures were transformed into branched alkylcyclohexanes at simultaneous high energy density (143 btu gal⁻¹ 10⁻³) and low freezing point (<123 K), meeting stringent specifications for military fuels (JP-10) as well. Monoalkylation of ABE mixtures with an initial water content of 12.1 wt%, trimer condensation of the obtained methyl ketones, and hydrodeoxygenation (HDO) reactions involve the three-step domino reactions. On account of satisfying performances of catalysts, the homogeneous fermentation products containing high water content (12.1 wt%) were converted efficiently and smartly into two-layer mixtures, which are phase-separable, thus improving the economic feasibility by reducing energy-intensive purifications and comply with the principle of “green chemistry”. Besides, the study mechanism revealed that the medium-strong and strong base sites play a vital role in the trimer condensation. Overall, this work not only opens up new avenues for the production of high-performance aviation fuel and biodiesel from fermentation products, but also offers great promise for the rational design and fabrication of heterogeneous catalysts with high activity.