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Xiao, W., Pang, A., Wang, X., Liu, J., and Han, L. (2014). "Separation and analysis of microwave-assisted liquefied products of corn stover," BioRes. 9(4), 7109-7118.


Corn stover was successfully liquefied by microwave heating at 160 °C with ethylene glycol (EG) used as the solvent and sulfuric acid as a catalyst. Gas chromatography and mass spectrometry (GC-MS) data indicated that methyl esters, including 3-(2-methyl-1,3-doxolane-2-yl) propionic acid methyl ester (PAME), levulinic acid isopropyl ester (LAE), methyl laurate, and methyl palmitate were the major degradation compounds, in addition to EG derivatives in the liquefied product of corn stover (LPCS). For high value-added utilization of LPCS, solvent extraction was applied to characterize the components and to separate it into useful fractions. After being dispersed in water, the water-soluble fraction of the LPCS was then extracted with organic solvents, including hexane, chloroform, diethyl ether, and ethyl acetate. Levulinic acid isopropyl ester showed the highest distribution in chloroform and ethyl acetate, while the lowest in hexane and ether. Levulinic acid isopropyl ester was selectively enriched to 28.76% and 43.65% by sequential extraction with chloroform and ethyl acetate, respectively, in accordance with the quantitative analysis.
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