Production of Low-Freezing-Point Highly Branched Alkanes through Michael Addition

A new approach for the production of low freezing point, high-quality fuels from lignocellulose derived molecules was developed with Michael addition as the key step. Among the investigated catalysts, CoCl2*6H2O was found to be the most active for Michael addition of 2,4-pentanedione with FA (single aldol adduct of furfural and acetone, 4-(2-furanyl)-3-butene-2-one). Over CoCl2*6H2O, a high carbon yield of C13 oxygenates (about 75%) can be achieved under mild conditions (353 K, 20 h). After hydrodeoxygenation, low freezing point (< 223 K) branched alkanes with 13 carbons within jet fuel ranges were obtained over Pd/NbOPO4 catalyst. Furthermore, C18,23 fuel precursors could be easily synthesized through Michael addition of 2,4-pentanedione with DFA (double-condensation product of furfural and acetone) under mild conditions and the molar ratio of C18/C23 is dependent on the reaction conditions of Michael addition. After hydrodeoxygenation, high density (0.8415 g/ml) and low freezing point (< 223 K) branched alkanes with 18, 23 carbons with lubricant range were also obtained over Pd/NbOPO4 catalyst. These highly branched alkanes can be directly used as transportation fuels or additives. This work opens a novel strategy for the synthesis of highly branched alkanes with low-freezing-point from renewable biomass.