Modeling Phase Equilibrium of Common Sugars Glucose, Fructose, and Sucrose in Mixed Solvents

The industrial processing of sugars
and sugar-containing mixtures
is gaining widespread use as a form of renewable manufacturing from
biomass. To aid in process modeling for design and optimization, a
commonly available thermodynamic model is needed that describes the
phase equilibrium of these compounds. This work compiles and compares
models for solid–liquid and vapor–liquid phase equilibrium
from the available data for the representative sugars glucose, fructose,
and sucrose in the representative solvents water, methanol, and ethanol,
including data for multisugar, multisolvent systems. The nonrandom
two-liquid (NRTL) model was chosen for these systems because of its
widespread use in industry and the availability of parameters for
many solvents and cosolutes. The association-NRTL (aNRTL) model was
investigated as an improvement for modeling sugars, which may experience
a high degree of association because of their many hydroxy groups.
Both models accurately capture the data and are able to predict the
behavior of multisugar systems with only solute–solvent interaction
parameters. The aNRTL model shows an improvement over the baseline
NRTL model that is most significant for sucrose, the component with
the highest association strength, and least significant for fructose,
which has the lowest association strength.