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Measurements of Reaction Enthalpies for Aqueous amine solutions for post combustion carbon capture applications
Abdurahim Abdulkadir, Mohammad Abu Zahra
2nd PCCC, 17-20 Sep, 2013 Bergen, Norway
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Research university Graduate level (MSc & PhD) only Focused on sustainable technology and clean energy In collaboration with Massachusetts Institute of Technology (MIT)
MASDAR INSTITUTE A RESEARCH DRIVEN UNIVERSITY
Masdar Institute – 100% solar powered campus
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SEPARATION TECHNOLOGY LABORATORY (STL)
The Research Focus is the CO2 Post-Combustion Capture
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PRESENTATION OUTLINE
Introduction Materials Experimental Method Results Conclusions
Future Work
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The OVERALL SCOPE OF THE PROJECT
• Project Title : DEVELOPMENT OF NEW SORBENT SYSTEMS FOR CO2 POST-COMBUSTION CAPTURE
• Phase I: Process Simulation and Solvent Screening for Alkanolamine blends
• Phase II: Thermodynamic measurement and modeling of heat of absorption and specific heat of the most promising stand-alone and blends of amine from phase I
• Phase III : Reaction Kinetics measurements of the most promising stand-alone and blends of amine from phase I
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ABSORPTION CAPACITY SET-UP
EQUILIBRIUM EQUIPMENT SET-UP
Phase I of the Project
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Solvent Screening set-up
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RESULTS FROM PHASE I
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Ref: Adewale Adeosun
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INTRODUCTION
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o Post-combustion capture (PCC) with amine scrubbing is seen as a useful route to reducing carbon emissions
o PCC is energy intensive – solvent regeneration accounts for the vast majority of costs associated with CCS, thus there is great interest in solvent design and solvent blends
o Sophisticated thermodynamic treatment required – cubic EoS not applicable, quuasichemical-based theories not ideal
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INTRODUCTION
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Heat of absorption is the Combination of heat of dissolution and heat of reaction between CO2 and amine
Heat of absorption = - Heat of Regeneration • High Heat of Absorption – favors to increase the kinetics of the reaction and reduces the absorption height
• Low Heat of Absorption – favors to decrease the regeneration cost by reducing the steam supply
The best solvent is the one with High absorption heat Easily can be regenerated
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Heat of absorption from Model and Experiment
• Heat of absorption from Model is obtained from Vapor-Liquid Equilibrium (VLE) using Gibbs Helmholtz thermodynamic relation which is (at particular loading)
Differential in loading but integral in temperature
• Heat of absorption from Calorimeter is combination of heat of dissolution and heat of reaction of CO2 and amine from zero loading to the final loading (at particular temperature or isothermal)
Integral in loading but differential in temperature
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Calorimetric measurement • Direct calorimetric measurements provide accurate values of the enthalpy of
absorption, reflecting both the heat effects due to physical dissolution of the gas in the solvent and the chemical reaction between CO2 and amine
• The enthalpy of CO2 absorption is directly related to the reaction kinetics of the solvent in the absorber and the energy requirement for the solvent regeneration, and it is desirable that the value be known as accurately as possible to avoid Uneconomic over design for absorber and stripper.
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MATERIALS Monoethanolamine OR MEA
Viscous colourless liquid
Boiling point = 1700C Vapor Pressure = 30 Pa at 200C pH = 12.1 (25% solution)
Solubility = Miscible in water Diethanolamine OR DEA
Viscous colourless liquid Boiling point = 2170C Vapor Pressure = <1 Pa (at 20 0C) pH = 11.5 at 105 g/l at 250C Water Solubility = 105 g/l at 200C
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MATERIALS Piperazine or PZ (poly secondary cyclic amine)
White Crystalline Solid
Boiling point = 145 0C Vapor Pressure = 21 Pa at 200C pH = 10.8-11.8 at 100 g/l
Completely soluble in water
3-Piperidinemethanol OR 3-PM
(Secondary cyclic alkanolamine)
White Crystalline Solid Boiling point = 106 0C at 47 Pa Vapor Pressure = 306.6 Pa (at 25 0C) Completely soluble in water
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Tertiary/sterically amines: N-Methyldiethanolamine OR MDEA
Viscous colourless liquid
Boiling point = 1700C Vapor Pressure = 1 Pa at 200C pH = 11.5 at 100 g/l at 200C
Completely soluble in water
2-Amino-2-methyl-1-proanol OR AMP
Viscous colourless liquid Boiling point = 165 0C Vapor Pressure = <10 Pa at 25 0C pH = 11-12 at 8.9 g/l at 250C water Solubility = 8.9 g/l at 200C
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EXPERMENTAL METHOD
Micro-reaction calorimeter THT
Bench-scale 85% phosphoric acid titration set-up
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Thermo gravimetric differential scanning calorimeter (TGA-DSC)
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CSIRO Energy Center
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Micro-Reaction Calorimeter Experimental Set-up
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Micro-Reaction Calorimeter Experimental Set-up
N2 CO2
Dessiccant column
Gas in
T1 V1
V3
MFC
By-pass
Gas out
T2 V2
Calorimeter
Analysiscell
Referencecell
Shunt
Cap
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Micro-Reaction Analysis
Heat of Absorption for 3/3 M MEA/3PM
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Micro-Reaction Analysis
Specific Heat of 30 wt % MEA
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Thermo gravimetric differential scanning calorimeter (TGA-DSC)
Electrical signal over time in the measurement of cp in a 40wt% DEA solution from 25 – 135oC.
-80
-60
-40
-20
0
20
40
0 2000 4000 6000 8000 10000 12000 14000 16000 18000
electr
ical si
gnal
(uV)
time (seconds)
-80
-60
-40
-20
0
20
40
5000 5200 5400 5600 5800 6000 6200 6400 6600 6800 7000
electr
ical si
gnal
(uV)
time (seconds)
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Thermo gravimetric differential scanning calorimeter (TGA-DSC)
The specific heat capacity of the sample, cp in J/g.K is given by:
)AA.(m
)AA.(m)T(cp)(
boltanocsample
blanksampleoct
oct −−
=−−
Tcp
• T is the average temperature of the ramp (i.e. ramp from 20 – 30oC is reported at 25.0oC),
• Asample, and Ablank and Aoctanol are the trapezoidal numerical integration of the ZDSC electrical singal (in µV.s) of the sample, blank, and standard (1-octanol), respectively over the time of the temperature increment.
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Specific Heat of Stand-alone Amines in the range of 30-80 0C
RESULTS
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30 40 50 60 70 803.5
3.6
3.7
3.8
3.9
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4.1
4.2
4.3
Temprature (0C)
CP (J
/0C*
g)
20wt%PZ10wt%AMP3M-3PM2M-3PM
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Specific Heat of Blends of Amines in the range of 30-80 0C
RESULTS
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30 40 50 60 70 803.5
3.6
3.7
3.8
3.9
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4.1
4.2
4.3
Temprature (0C)
CP (J
/0C*
g)
10/20wt%-AMP/PZ10/20wt%-MDEA/PZ3/3M-MEA/3PM3/2M-MEA/3PM2/3M-MEA/3PM
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Thermo gravimetric differential scanning calorimetry (TGA-DSC)
RESULTS
Specific Heat Capacities
Work in progress for
Amine Blends
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RESULTS
Aqueous solutions of MEA,DEA,MDEA , PZ and blends@ 400C
AMINES CONCENTRATION HEAT OFABSORPTION ( kJ/mol CO2 )
LOADING CAPACITY (mol CO2/mol Amine)
MEA 30wt% 87.8 0.51
MDEA 10wt% 56.76 0.63
AMP 10wt% 70.25 0.72
PZ 20wt% 115.15 0.62
AMP/PZ 10/20wt% 93.4 0.82
MDEA/PZ 10/20wt% 79.75 0.78
Work in progress for
60-120 0C
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CONCLUSIONS • A micro reaction calorimeter was used to measure the enthalpies of absorption and heat
capacity of different aqueous solutions of MEA,DEA,MDEA,AMP and PZ with their blends
• The significant difference in enthalpies is mostly due to the endothermic bicarbonate formation reaction in the case of tertiary amine, which reduce the magnitude of the enthalpy while high enthalpy of absorption is measured for primary amine due to the exothermic carbamate formation
• High Heat of absorption of piperazine reduced by blending it with tertiary amine and
sterically hindered amines .
• Loading capacity of Piperazine with sterically hindered amine is higher than loading
capacity of Piperazine with tertiary amine.
• MDEA/PZ blend is having low heat of absorption and high CO2 loading capacity.
• The measured data can be used for modeling CO2 absorption/desorption system when the
above aqueous solutions are used
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FUTURE WORK
• Thermodynamic Modeling of the heat of absorption for MEA,DEA,MDEA,3-PM,AMP and their blends using activity model, the Specific Ion Interaction Theory (SIT) proposed by Dr. Graeme Puxty from CSIRO
• Measurement of heat of absorption for different aqueous amine solutions at different temperature ranges and CO2 loading
• Measurement of Specific heat and heat of absorption of other aqueous amine solutions with their blends
• Phase II , Kinetics of amine blends and also advanced amine solvent screenging
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Thank You For Your Attention