95. Ramsurn,
Hema; Gupta, Ram B., Deoxy-liquefaction
of switchgrass in supercritical water with calcium formate as an in-situ hydrogen donor, Bioresource
Technology (2013), 143, 575–583.
Abstract
Switchgrass was liquefied in supercritical water (SCW)
using Ca(HCOO)2
as an in-situ source of hydrogen to
enhance deoxygenation and the quality of the biocrude obtained. In
SCW, Ca(HCOO)2
produces hydrogen via decomposition and hydrolysis reactions, and
simultaneously switchgrass hydrolyzes to form
oxygenated hydrocarbon compounds.
Because of the close proximity of the newly-formed hydrogen and active
hydrocarbons, hydrodeoxygenation occurred whereby some
of the oxygenated compounds were upgraded by the removal of oxygen in the form
of water. The analysis of the so-formed biocrude revealed the presence of benzene, polyaromatic hydrocarbons, and alkyl phenolics. The benzene formation is attributed to the
hydrogenation of phenols but also due to the Diels-Alder alkene addition, followed
by dehydrogenation. The addition of Ca(HCOO)2
doubled the yield of biocrude (10 wt%)
and increased the heating value from 28 to 34 kJ/g. Formic acid increased in the aqueous biocrude due to the enhanced decomposition of xylose and
glucose.
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