Synthesis of Renewable C8–C10 Alkanes with Angelica Lactone and Furfural from Carbohydrates

For the first time, proline-based ionic liquids were reported as effective catalysts for the aldol condensation of angelica lactone with furfural, two platform compounds which were obtained by the hydrolysis–dehydration reactions of cellulose and hemicellulose. Among the investigated catalysts, a renewable ionic liquid that was prepared with biomass-derived choline and l-proline (denoted as ChPro) demonstrated the highest activity. Over the ChPro catalyst, 86% carbon yield of C10 oxygenate was obtained under mild conditions (353 K, 1 h). After being hydrogenated over the Pd/C catalyst and hydrodeoxygenated under the promotion of the Pd–Cu/SiO2, the aldol condensation product of angelica lactone with furfural was transmuted into C8–C10 alkanes within the carbon chain range of jet fuel and diesel. Compared with the Cu/SiO2 and Pd/SiO2, the bimetallic Pd–Cu/SiO2 demonstrated higher activity and/or selectivity to C8–C10 alkanes for the hydrodeoxygenation of hydrogenated aldol condensation product. According to the characterizations of X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, and CO Fourier transform infrared, the excellent catalytic performance of Pd–Cu/SiO2 can be comprehended by the Pd–Cu alloy particles formed during the preparation of this catalyst.