Efficient synthesis of C15 fuel precursor by heterogeneously catalyzed aldol-condensation of furfural with cyclopentanone

The aldol-condensation reaction of biomass-derived furfural and cyclopentanone coupled with hydrogenation/hydrodeoxygenation is a promising route for the production of renewable high-quality diesel or jet fuel. In this paper, we focus on the heterogeneously catalyzed aldol condensation of furfural with cyclopentanone, in order to maximize the yield of 2,5-bis(2-furylmethylidene) cyclopentan-1-one (F2C, a C-15 fuel precursor). Experiments were conducted over a series of solid-base catalysts and it was found that potassium fluoride impregnated alumina shown the highest catalytic efficiency. We further investigated the effect of different parameters on the performance of KF/gamma-Al2O3, including KF loading amount, solvent, reaction time and temperature. Over KF/gamma-Al2O3 with a 33% KF loading amount, the aldol reaction achieved an F2C molar yield up to 95.4% at 333 K within 2 h. Under the nearly optimal condition, the separated solid product is almost F2C with a purity of 100%, providing a high-quality biofuel precursor for the next processing step.