Researchers in China have directly synthesized gasoline- and diesel-range C6-C15 branched alkanes in high carbon yield (~80%) via the self-condensation of acetone and the subsequent hydrodeoxygenation over a dual-bed catalyst system. A paper on their work appears in the RSC journal Green Chemistry.
Acetone is a by-product in the production of bio-butanol via the acetone-butanol-ethanol (ABE) fermentation of lignocellulose. In a typical ABE fermentation, butanol, acetone and ethanol are produced at a weight ratio of 6:3:1.4 Acetone can also be produced by ketonization of acetic acid—a low-cost lignocellulosic platform compound which is obtained as a by-product in furfural production or from the fermentation of lignocellulose.
The new work thus offers a potential route for the synthesis of drop-in hydrocarbon fuels using acetone derived from the ABE fermentation of lignocellulose.
|Strategy for the direct production of gasoline and diesel range branched alkanes over a dual-bed catalyst system. Sheng et al. Click to enlarge.|
In the first bed, the acetone was converted to C6-C15 ketones and alcohols using a Pd-modified MgAl-hydrotalcite (MgAl-HT) catalyst. In the second bed, the C6-C15 ketones and alcohols generated in the first bed were further hydrodeoxygenated to C6-C15 branched alkanes—which can be used as renewable gasoline and diesel.
During a 24-hour continuous test, the carbon yield of C6-C15 branched alkanes only slightly decreased from 84.2% to 74.9%. After in-situ regeneration with a hydrogen flow at 573 K for 2 hours, the activity of the dual-bed catalyst system restored to its initial level.
Xueru Sheng, Ning Li, Guangyi Li, Wentao Wang, Ai-Qin Wang, Yu Cong, Xiaodong Wang and Tao Zhang (2016) “Direct synthesis of gasoline and diesel range branched alkanes with acetone from lignocellulose” Green Chem., 2016, Accepted Manuscript DOI: 10.1039/C6GC01127F