Distillation of ionic liquid-water systems ACel program seminar 2015

Ville Alopaeus, Kaj Jakobsson, Petri Uusi Kyyny, Alexandr Ostonen, Waqar Ahmad

Aalto, Chemical Technology

Content

• Focus areas of Chemical Engineering group at Aalto

• Scale up and process development based on small

scale experimentation and modeling

• Distillation and evaporation as separation techniques

• VLE studies for IL

• Piloting and recycling studies in ACel

2

Focus areas of the Chemical Engineering group at Aalto

1. Measurement of phase

equilibria

2. Fundamental phenomenon

based modeling of chemical

process units, mixing research

3. Microprocess technology

3

Traditional process

development

Parallel basic phenomena studies

30

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50

60

70

80

90

100

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

x1, y1

P/k

Pa

Data, phenomena models Process model

Fast and reliable scale-up directly from small scale

2003

Model based enhanced process

development

Distillation and evaporation

• Distillation and evaporation are very similar unit

operations in their physical basis

• They are based on formation of vapor phase by

adding heat, and distribution of components

based on their volatility

• The difference is that in evaporation there are

typically components that do not vaporize at all

• Distillation is very energy consuming due to the

need for reflux. Evaporation can be much more

effective if multi-stage evaporators can be used

6

Systematic vapor-liquid equilibrium (VLE) study

1. Preliminary vapor pressure measurements and modeling of

DBN and [DBNH][OAc] using vacuum distillation

2. Vapor-liquid equilibria measurements of IL+water systems

using static apparatus

7

Systematic vapor-liquid equilibrium (VLE) study

8

Vapor pressures and vaporization enthalpies of DBN

mol/kJ64.62)K298(m

g

l H

Measured points: 54

Temp. range: 273 - 353 K

VLE measurements, [DBNH][OAc]-water

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Vapor-liquid equilibria measurements and modeling in Aspen+, [DBNH][OAc]-water

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Challenges

Limited information about the system for detailed design

• Experimental VLE data

• Physical properties (density, viscosity, heat capacity, thermal conductivity...)

• Reaction equilibrium and kinetic data (ion equilibrium & decomposition /

hydrolysis)

• Desired purity of products (highest amount of water in IL and highest amount

of IL in the bath tolerated by the process)

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Ionic liquid recycling scheme design and piloting

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Spin bath volume = 150 L

IL spun per batch = 2-2.5 L

Evaporator feed= 20-22 L /day

Test-runs on thin film evaporator at UIC GmbH Germany

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Test-runs on thin film evaporator at UIC GmbH Germany (Results from test-run)

Test # 1 2 3 4 5 6 7 8 9

Vacuum (mbar) 31 31 31 31 31 31 26 21 16

Evaporator jacket Temp. (˚C) 79 78 77 83 87 94 77 78 77

Feed rate (kg/h) 2.10 2.98 3.80 3.34 4.22 4.08 4.26 3.59 4.30

Feed temp. (˚C) 78 78 77 78 78 78 78 78 77

Residue temp. (˚C) 62 65 60 60 60 60 60 60 60

Distillate temp. (˚C) 32 32 32 33 34 36 32 31 28

Condenser temp. (˚C) 8 10 11 9 11 10 10 10 11

Distillate (w %) 75.4 77.4 77.3 78.8 79.3 80.6 78.6 79.6 77.7*

Residue (w %) 24.6 22.6 22.7 21.2 20.7 19.4 21.1 20.4 22.3

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*Some additional condensate in the cold trap

Ionic liquid recycling scheme design and piloting (Test-runs at UIC GmbH Germany)

Tfeed = 351 K

Tresidue = 335 K

Tdistillate = 305 K

From composition analysis

Residue has 11.7w% water

Distillate has 99.7w% water

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Feed

Residue

Distillate

373K

299K

Operating

temperature

window

Temperature (pressure)

hydrolysis

Cooling

Conclusions • Scale up and design of industrial processes is best

done by combining small scale experiments into a

unified modeling tool, and using the tool for design

• In separation processes based on vaporization,

vapor-liquid equilibria and enthalpy variables are

the most important

• This approach should be based on carefully

designed experiments and piloting to find potential

pitfalls

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Thank you!

A? A!