86. Ramsurn,
H., Gupta, R.B., Production of Biocrude from Biomass
by Acidic Subcritical Water Followed by Alkaline Supercritical Water Two-Step
Liquefaction. Energy & Fuels 2012 26
(4), 2365-2375.
Abstract
Increased
demand in transportation fuels, environmental concerns and depletion of fossil
fuel require development of efficient conversion technologies for
second-generation biofuels. The main
objective of this work is to efficiently liquefy biomass into energy-dense biocrude. A novel two-step process is proposed in which
acidic subcritical-water followed by alkaline supercritical-water media are
utilized for the liquefaction. The
concept is tested with switchgrass. The first step is
carried out at 200 °C in acidic subcritical water to liquefy hemicelluloses to biocrude while avoiding the repolymerization
reactions which would otherwise produce char. In the second step, the remaining
un-liquefied biomass (biomass-H) is subjected to supercritical water at 380 °C
with Ca(OH)2
as catalyst for minimizing the formation of char, enhancing lignin solubilization and therefore increasing liquefaction of the
remaining polysaccharides toward biocrude. The
proposed two-step liquefaction produces significantly higher amount of biocrude as compared to the traditional one-step
process. The yield of biocrude from the proposed process is 40% on mass basis and
67% on energy basis of the feedstock biomass.
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