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, CoCl(2)6H(2)O was found most active for the Michael addition of 2,4-pentanedione with FA (single aldol adduct of furfural and acetone, 4-(2-furanyl)-3-butene-2-one). Over CoCl(2)6H(2)O, a high carbon yield of C-13 oxygenates (about 75%) can be achieved under mild conditions (353K, 20h). After hydrodeoxygenation, low-freezing-point (<223K) branched alkanes with 13-carbons within jet fuel ranges were obtained over a Pd/NbOPO4 catalyst. Furthermore, C-18,C-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 C-18/C-23 is dependent on the reaction conditions of Michael addition. After hydrodeoxygenation, high density (0.8415gmL(-1)) and low-freezing-point (<223K) branched alkanes with 18, 23carbons within lubricant range were also obtained over a Pd/NbOPO4 catalyst. These highly branched alkanes can be directly used as transportation fuels or additives. This work opens a new strategy for the synthesis of highly branched alkanes with low freezing point from renewable biomass.