Ethyl
levulinate has shown great potential as a green fuel additive
for gasoline, diesel, and biodiesel. One alternative for its synthesis
is the direct heterogeneously catalyzed esterification of levulinic
acid with ethanol. Most of the catalytic processes already reported
for this system, however, rely on large residence times to deliver
appreciable levulinic acid conversions. This work presents experimental
and modeling results on the esterification kinetics of levulinic acid
with ethanol assisted by supercritical carbon dioxide (scCO2) and catalyzed by Amberlyst-15 in a fixed-volume batch reactor.
We explore different molar ratios, catalyst amounts, temperatures,
and scCO2 loads. The presented reaction scheme leads to
near-equilibrium levulinic acid conversions after less than 60 min
at most of the evaluated conditions. To represent the phase-behavior
of CO2 + reactants and products, the Peng–Robinson
equation of state with a quadratic mixing rule was used. We found
that, at most of the experimental conditions, the reaction takes place
in a two-phase system due to scCO2; thus, a v-T flash algorithm was coupled to the kinetic model. The proposed kinetic
modeling is one of the first attempts to simulate scCO2-assisted reactions in heterogeneous catalytic systems in which the
phase partition inside the reactor vessel is considered.
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