http:www.icpf.cas.cz

1
http//www.icpf.cas.cz/
Coupled esterification reaction in ionic liquids
and product recovery by pervaporation
P. Izák1, N.M.M. Mateus2, C.A.M. Afonso2, J.G.
Crespo2
1Department of Separation Processes, Institute of
Chemical Process Fundamentals, Rozvojová 135,
16502 Prague 6, CZ 2Institute of Chemistry,
University of Rostock, Albert Einstein Str.3a,
18059 Rostock, Germany 3Institute of Chemical
Sciences and Engineering, Swiss Federal Institute
of Technology, 1015 Lausanne, Switzerland 4Departm
ent of Physical Chemistry, Institute of Chemical
Technology, Technická 5, 16628 Prague 6, Czech
Republic
2
The aim

• Conversion enhancement of esterification
  reactions taking place in RTILs by pervaporation
• Modeling of the esterification reaction coupled
  with pervaporation
• Prediction of process variables influence on the
  esterification reaction

3
Room Temperature Ionic Liquids
(R methyl group, R octyl group, R decyl
group), X _ PF6_, X _ BF4 _ )

• Non-measurable vapour pressure ? Green solvent
• High ionic conductivity and thermal stability
• Ability to solubilize a large range of organic
  molecules and transition metal complexes

4
Room Temperature Ionic Liquids

• Do not permeate through either organophilic or
  hydrophilic dense membranes
• Possibly an environmentally benign alternative to
  classical organic solvents
• High viscosity and low heat transfer
• Purification of ionic liquids

5
Experimental
bmim
BF4 CH3COOH H2O
p-TsOH
60C
A
B
E
W

• Hydrophobic RTIL bmim PF6 at temperatures
  over 50C - hydrolysis producing HF and PO43-
• The selected dried bmim BF4 had viscosity
  26 cP at 60C
• Due to crystallization on the lid of the vessel,
  a 50 excess of
• (-)-Borneol was used

6
Experimental

• Esterification in closed vessel with minimized
  headspace
• Water content in the reaction mixture was
  determined by
• automatic Karl-Fisher titration (Aquapal III)
  
• Esterification reaction was monitored by GC
  (CP-9001) using a FFAP polar capillary column
• Pervaporation membrane for water removal PVA
  membrane PERVAP 2205, SULZER (suitable for
  organic acids without limitation)

7
Pervaporation set-up
Pervaporation experiment standard laboratory
pervaporation set-up with effective membrane area
of 100 cm2 downstream pressure p 0.06 mbar
Thermostat
8
Esterification at 60C
cat, kf
kb
9
Model assumptions
    1. Isothermal operation    2. Ideal
mixing for all reactants in reactor
3. Negligible permeation of reactants through
the membrane
The consumption of acetic acid can be expressed
by
(1)
Moles of acetic acid consumed during
esterification can be expressed as
(2)
10
Differential equations for modeling
For the other components it can be derived
(3)
(-)-Borneol
(4)
Water
(5)
(-)-Bornyl acetate
(6)
where R is the process variable
11
Volume change in the reactor
Taking into consideration that the ionic liquid
does not permeate through the PVA membrane, dV/dt
can be expressed by
(7)
All differential Eqs. (2-5, 7) were solved by the
least square method using Scientist software.
12
Fitting of esterification reaction
kf (2.72 0.13)10-4 m3 mol-1 h-1
13
Esterification coupled with pervaporation
Jb 8.9610-3 mol m-2 h-1
14
Drying of bmim BF4 by PV
15
Simulation of esterification coupled with
pervaporation
Parameters used for the simulation...............
.......................................... Jw
(-1.19W2 2.42 W ) mol m-2 h-1 Jb
8.9610-3 mol m-2 h-1 ....K K (0.629
0.038) kf (2.74 0.13) 10- 4 m3 mol-1 h-1
R 48 m-1
16
Comparison of esterification with and without
pervaporation
17
Effect of SM/V ratio on water concentration in
the reactor
18
Effect of SM/V ratio on conversion to (-)-Bornyl
acetate in the reactor
19
Conclusions

• Thanks to pervaporation, the reaction conversion
  increased from 22.0 to 44.4 (increase by 102)
• Numerical simulation and experimental results
  showed a good agreement
• The process variable SM/V has a significant
  impact on the esterification conversion

20
Acknowledgement

• This research was supported by Marie Curie
  Intra-European and Marie Curie Reintegration
  Fellowships within the 6th European Community
  Framework Programme and by Purkyne Fellowship
  from Czech Academy of Science.
• Thank you for your attention!