Researchers synthesize diesel- and jet-range cycloalkanes from lignocellulosic platform compounds
18 July 2014
Researchers at the Dalian Institute of Chemical Physics, Chinese Academy of Sciences, have synthesized, for the first time, a mixture of C9−C15 branched alkanes and cycloalkanes with relatively higher density from 2-Methylfuran (2-MF) and cyclopentanone (CPO)—selective hydrogenation products of furfural, which can be produced in industrial scale with lignocellulose.
Most work done so far with lignocellulose-based platform compounds has concentrated on the production of diesel (C9−C21) or jet fuel (C8−C16) range straight-chain alkanes and/or branched-chain alkanes, the team notes in their paper in the ACS journal Energy & Fuels. Although those alkanes have good thermal stability and excellent combustion efficiency, their lower densities require blending with conventional jet fuel (a mixture of straight-chain alkanes, branched-chain alkanes, and cyclic hydrocarbons) to meet the specifications of aviation fuel.
(Broadly, branched alkanes have relatively higher cetane values, and are favorable for diesel fuel. Cycloalkanes have higher densities and volume heat values, which are desirable for aviation fuel.)
Compared with straight-chain alkanes and branched-chain alkanes, cycloalkanes have higher densities and volumetric heating values due to robust ring strain. To fulfill the need of aviation fuel, cycloalkanes or aromatics should also be synthesized and added to the biojet fuel to increase the density or volumetric heating of the fuel. As another possible application, the cycloalkanes can also be added into the biodiesel to increase its mileage per liter (or gallon).
Cyclopentanone (CPO) is a selective hydrogenation product of furfural and a main component of bio-oil from the pyrolysis of biomass. The cyclic structure of this compound makes it a promising feedstock in the production of cycloalkanes. To our knowledge, there is no report about the production of diesel or jet fuel range cycloalkane by the combination of HAA [hydroxyalkylation/alkylation] and HDO [hydrodeoxygenation] reactions. In this work, a mixture of C9−C15 branched alkanes and cycloalkanes with relatively higher density was synthesized, for the first time, by the solid acid-catalyzed HAA reaction of 2-MF and CPO, which can be easily derived from lignocellulose, followed by the HDO over Ni-base catalysts.—Li et al.
In their study, they first performed the hydroxyalkylation/alkylation (HAA) reaction of 2-MF and CPO in a flask. The resulting diesel or jet fuel precursors from the HAA of 2-MF and CPO then underwent hydrodeoxygenation in a fixed-bed reactor, developed by the team in their earlier studies.
Of the solid acid catalysts, Nafion-212 resin exhibited the best activity and selectivity for the HAA of 2-MF and CPO. The researchers attributed the excellent performance of the resin to the high acid strength of this catalyst.
After the HDO of the HAA products of 2-MF and CPO over several nickel catalysts, a mixture of jet fuel range branched alkanes and cycloalkanes with relatively higher density was obtained at high carbon yield.
Guangyi Li, Ning Li, Xinkui Wang, Xueru Sheng, Shanshan Li, Aiqin Wang, Yu Cong, Xiaodong Wang, and Tao Zhang (2014) “Synthesis of Diesel or Jet Fuel Range Cycloalkanes with 2-Methylfuran and Cyclopentanone from Lignocellulose,” Energy & Fuels doi: 10.1021/ef500676z
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