REACTION KINETICS OF THE ESTERIFICATION OF ETHANOL ...

Intelligent Column Internals for Reactive Separations Page 4 of 5
Deliverable 22 Issued: 24.08.01
sults was obtained for 1.5 th order in AcOH (m in equations 2 and 4 is 1.5). The resulting equilibrium
constants at 55 °C and 65 °C are 6.68 and 5.51, respectively.
For determination of the kinetic constants k1 and k2 the same reactor was used, but at higher liquid
flow rates: 2-25 ml/min. The corresponding W/F ratios are 0.03-0.37 s kgcat/m 3 . The kinetic constants
were calculated from the product concentrations (EtOAc when AcOH and EtOH were fed,
AcOH and EtOH when EtOAc and water were fed) using a Mathcad worksheet, in which the reactor
was modelled as an ideal plug flow reactor. The experimental and calculated ethyl acetate concentrations
in the reactor effluent are shown in figure 1.
calculated
60
40
20
0
Figure 1. Experimental (x-axis) and simulated (y-axis) ethyl acetate concentrations in the reactor effluent.
The kinetic equations 2 and 3, and the parameters given in table 1 were used for the simulations.
At 65 °C the value for k1 is 0.147 mol kgcat -1 s -1 , and k2 is 0.0268 mol kgcat -1 s -1 . At 55 °C the value
for k1 is 0.0874 mol kgcat -1 s -1 , and k2 is 0.0131 mol kgcat -1 s -1 . The activation energy for the ester
formation reaction is 48.3 kJ mol -1 . The activation energy for the ester hydrolysis reaction is 66.2 kJ
mol -1 . The pre-exponential factors (see equation 5) are 4.24⋅10 6 mol kgcat -1 s -1 for the ester formation
and 4.55⋅10 8 mol kgcat -1 s -1 for the ester hydrolysis. The most important parameters are summarised
in the table below.
Table 1. Kinetic parameters for ethyl acetate formation and hydrolysis on Purolite CT179.
Parameter Units Value
Keq 55 °C - 6.68
Keq 65 °C - 5.51
k1 55 °C mol kgcat -1 s -1 0.0874
k1 65 °C mol kgcat -1 s -1 0.147
k2 55 °C mol kgcat -1 s -1 0.0131
k2 65 °C mol kgcat -1 s -1 0.0268
k1,o mol kgcat -1 s -1 4.24⋅10 6
k2,o mol kgcat -1 s -1 4.55⋅10 8
EA,1 kJ mol -1 48.3
EA,2 kJ mol -1 66.2
Ethyl acetate parity plot (weight%)
0 20 40 60
experimental