Production of liquid hydrocarbon fuels with acetoin and platform molecules derived from lignocellulose

Acetoin, a novel C₄ platform molecule derived from new ABE (acetoin-butanol-ethanol) type fermentation via metabolic engineering, was used for the first time as a bio-based building block for the production of liquid hydrocarbon fuels. A series of diesel or jet fuel range C₉-C₁₄ straight, branched, or cyclic alkanes were produced in excellent yields by means of C-C coupling followed by hydrodeoxygenation reactions. Hydroxyalkylation/alkylation of acetoin with 2-methylfuran was investigated over a series of solid acid catalysts. Among the investigated candidates, zirconia supported trifluoromethanesulfonic acid showed the highest activity and stability. In the aldol condensation step, a basic ionic liquid [H₃N⁺-CH₂-CH₂-OH][CH₃COO^-] was identified as an efficient and recyclable catalyst for the reactions of acetoin with furan based aldehydes. The scope of the process has also been studied by reacting acetoin with other aldehydes, and it was found that abnormal condensation products were formed from the reactions of acetoin with aromatic aldehydes through an aldol condensation-pinacol rearrangement route when amorphous aluminium phosphate was used as a catalyst. And the final hydrodeoxygenation step could be achieved by using a simple and handy Pd/C + H-beta zeolite system, and no or a negligible amount of oxygenates was observed after the reaction. Excellent selectivity was also observed using the present system, and the clean formation of hydrocarbons with a narrow distribution of alkanes occurred in most cases.