Ionic Liquids for Post Combustion CO2-Absorption
12th MEETING of the
INTERNATIONAL POST-COMBUSTION CO2 CAPTURE NETWORK
David Wappel1), Guenter Gronald2), Roland Kalb3) and Josef Draxler1)
1) University of Leoben, Institute of Process Technology and Industrial Environmental
Protection Austria
Protection,
2) AE&E Austria GmbH & Co KG
3) proionic Production of Ionic Substances GmbH
29th September - 1st October 2009
Regina, Canada
T
k
Targett off th
the W
Work
To investigate the ability of various task specific ionic
liquids (ILs) as potential CO2 capture solvents for PCC
Comparison of one selected task specific ionic liquid
to the reference solvent MEA
Slide 2
C
t t off th
k
Content
the W
Work
Laboratoryy Work:
Screening of ionic liquids for a quick evaluation of the
CO2 absorption
p
performance
p
Vapor-liquid equilibrium measurements
Calculation of the enthalpy of absorption
C l l i off the
Calculation
h energy demand
d
d for
f stripping
i i
Pilot Plant Testing:
Direct comparison of MEA and IL under real flue gas
conditions
Slide 3
Why Ionic Liquids?
Chemical
Looping
Biological
Processes
MOFs
Solid Sorbents
Enzymatic
Membranes
Membranes
Systems
Advanced Amine
Solvents
Advanced
Physical Solvents
Post Combustion
Amine Solvents
Pre Combustion
Pre-Combustion
Physical Solvents
Oxy Combustion
Cryogenic Oxygen
(Figueroa et al. 2008)
Slide 4
IIonic
i Li
id
Liquids
“Ionic liquids are salts with a melting temperature
belo the boiling point of water.
below
ate Most ionic liq
liquids
ids
have an organic cation and an inorganic anion. “
(Wasserscheid und Welton, 2008)
Advantages:
d
Application without any solvent possible
Myriad
different structures and variation p
possibilities of
y
anion and cation
Non measurable vapor pressure
Disadvantages:
High Viscosity
Currently high costs
Little Experience
Slide 5
S
i
E
i
t
Screening
Experiments
Fast investigation of CO2 absorption
performance with a small amount of
liquid.
Reference solvents
30w% Monoethanolamine (MEA)
30w% Potassium Carbonate (K2CO3)
Test of CO2 absorption at 25°C and
80°C
Qualitatively determination of the
absorption kinetics
Slide 6
S
i
E
i
t
Screening
Experiments
80 different ILs or IL-blends were tested
Pure ILs (without additive)
High viscosity
Low CO2 absorption performance
Slow absorption kinetics
Water as an additive
Better absorption
p
performance
p
Slide 7
S
Screening
i
E
Experiments
i
t
Solvent
30w%
48w% IL 8
MEA
in water
in water
30w%
K2CO3
in water
Δp25
[mbar]
-676
-691
-645
Δp80
[mbar]
-438
-480
-343
t25
[sec]
250
1600
5000
7000
t80
[sec]
150
400
1800
Slide 8
Viscosity of the ionic liquid water blend
depending on the water content
450
25°C
Dynamic Viscosity [mPas]
400
388 4
388,4
50°C
350
300
250
200
150
100
58,8
14,6
50
7,6
0
50%
54,6
20,8
55%
60%
65%
70%
w% Ionic Liquid
Slide 9
V
Li id E
ilib i
(VLE) M
t
Vapor-Liquid
Equilibrium
Measurements
Basis for energy
demand calculation
Validation with
MEA and
comparison with
the literature
VLE Measurements
of IL between 40°C
40 C
und 110°C
Austgen et al. (1991) and Ma’mum et al. (2005; 2007)
Slide 10
V
Vapor-Liquid
Li id Equilibrium
E ilib i
Curves
C
Slide 11
E
th l off Ab
ti
ΔHabs
Enthalpy
Absorption
Changing
g g of equilibrium
q
with temperature
p
expressed
p
with van‘t Hoff equation
d ln k ΔH Abs
=
dT
R ⋅T 2
⎯⎯
→
ΔH Abs
⎛
⎞
⎜ ∂ ln p ⎟
CO 2
⎟
= R ⋅⎜
⎜ ∂⎛ 1 ⎞ ⎟
⎜ ⎜T ⎟ ⎟
⎝ ⎝ ⎠ ⎠α
For the analyzed ionic liquid
ΔH Abs
kJ
= 41.1 ± 3.2
mol
Slide 12
E
d ffor th
i i
Energy D
Demand
the CO2 St
Stripping
Calculation for 30w% MEA and 60w% IL
Validation
ld
off model
d l with
h MEA literature
l
Different process parameters: Mean deviation only 1,3%
Standard p
process parameters
p
CO2-Concentration Flue Gas
13,3
vol%
CO2 Capture Rate
90
%
IL Concentration
60
w%
MEA Concentration
30
w%
Temperature Absorber
40
°C
Desorption Temperature
110
°C
Slide 13
E
d ffor th
i i
Energy D
Demand
the CO2 St
Stripping
Simplifications
p
No temperature dependency of enthalpy of absorption
Comparison of standard PCC process with obtained
VLE data – not veryy detailed optimization
p
of the CO2
absorption process
Calculations are based on equilibrium conditions – no
kinetic effects
Slide 14
E
Energy
D
Demand
d ffor th
the CO2 Stripping
St i i
60w% Ionic Liquid
in water
30w% MEA
in water
Equilibrium data from
experiment
Calculation
Stages absorption
2
2
2
2
Stages desorption
4
8
4
8
[molCO2/molSolvent]
0,65
0,68
0,242
0,242
[kJ/molCO2]
41,1
41,1
82
82
Solvent flow rate required
[m³/tonCO2]
36
40
14,5
14,5
Thermal heat requirement
[GJ/tonCO2]
4,18
3,43
4,78
4,12
Solvent loading inlet absorber
Heat of absorption Dhabs
Slide 15
L
b
t
W
kS
Laboratory
Work
Summery
Ionic Liquids
q
have a potential
p
for post-combustion
p
CO2 capture
Energy demand is slightly better than MEA
S l
Solvent
t Fl
Flow rate
t iis higher
hi h than
th for
f MEA solution
l ti
Drawbacks of ILs
High viscosity of pure ionic liquids
Slower kinetics
No operational experience for PCC
High price (production of small amounts)
Slide 16
Pil
ti
Pilott Pl
Plantt T
Testing
Maintain operational
p
experience
p
Long term stability (Degradation)
Corrosion
Absorption kinetics
Pilot plant performance
Small pilot plant for post combustion CO2 capture
Direct comparison of MEA and IL
Slide 17
CO2 Pil
Pilott Pl
Plantt
Hard coal fired power
p
plant
Characteristics
Ch
t i ti
VGas = 20 Nm³/h
dAbs = 15 cm
dDes = 12 cm
Fullyy instrumented
Fully balanceable
Slide 18
CO2 Pil
ti
Pilott Pl
Plantt T
Testing
Experiments
p
with 30w% MEA solution
Stable conditions
Demonstrate the functionality of the pilot plant
Average capture rate of 85-90%
Energy demand ~ 4.2 GJ/tCO2
Ionic liquid tests are scheduled in October 2009
Direct comparison of MEA and IL considering energy
p
performance
p
at “real conditions”
demand and capture
Slide 19
A k
Acknowledgement
l d
t
The authors thank the Federal Ministry for Transport, Innovation
and Technology (BMVIT), the Federal Ministry of Economy,
Family and Youth (BMWA) and the Austrian Research
Promotion Agency (FFG)
(
) for
f their
h financial
f
l support.
Slide 20
Thanks for your attention !!
David Wappel
[email protected]