Evaluation of Clean Fractionation Pretreatment for
the Production of Renewable Fuels and Chemicals from Corn Stover
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Abstract
Organosolv
fractionation processes aim to separate the primary
biopolymers in lignocellulosic biomass to enable more selective deconstruction
and upgrading approaches for the isolated components. Clean fractionation
(CF) is a particularly effective organsolv process that was originally
applied to woody feedstocks. The original CF pretreatment employed
methyl isobutyl ketone (MIBK), ethanol, and water with sulfuric acid
as a catalyst at temperatures ranging from 120 to 160 °C. Understanding
the feasibility and applicability of organosolv processes for industrial
use requires mass balances on the primary polymers in biomass, detailed
understanding of the physical and chemical characteristics of the
fractionated components, and viable upgrading processes for each fraction.
Here, we apply two CF approaches to corn stover, one with MIBK/ethanol/water
and acid and the other with MIBK/acetone/water and acid, with the
aim of understanding if these fractionation methods are feasible for
industrial application. We quantify the full mass balances on the
resulting solid, organic, and aqueous fractions and apply multiple
analytical methods to characterize the three fractions. Total mass
yields of the cellulose-enriched, hemicellulose-enriched, and lignin-enriched
fractions are near mass closure in most cases. For corn stover, the
MIBK/acetone/water CF solvent system is more effective relative to
the original CF method based on the enhanced fractionation susceptibility
of the aqueous and organic phases and the lower molecular weight distribution
of the lignin-enriched fractions. Overall, this work reports component
mass balances for the fractionation of corn stover, providing key
inputs for detailed evaluation of CF processes based on bench-scale
data