TCCS-10 in Trondheim, Norway, 17-19 June 2019
Project no 271501, ACT – Accelerating CCS technology
Corrosivity of degraded MEA solvent and fresh solvent added organic acids and salts
Kjell-Arne Solli (University of South-Eastern Norway, USN)
Zulkifli Idris (University of South-Eastern Norway, USN)
For Accelerating CCS Technologies: Carbon Capture, Utilisation and Storage (CCUS) • ALIGN project
(Accelerating Low carbon Industrial Growth) ALIGN-CCUS, work package Capture:
Long-term pilot testing
• Emissions control
• Solvent management
• Process dynamics and control
• Cost reduction
• USN is partner in Solvent Management
TCCS-10 in Trondheim, Norway, 17-19 June 2019 2
Background: Degradation of solvent monoethanolamine (MEA)
TCCS-10 in Trondheim, Norway, 17-19 June 2019 3
CO2 absorption in amine – still a challenging task
• Degradation of solvent
• Corrosion of equipment
Experience RWE pilot 2009+2018
• Downstream the Niederaussem lignite-fired power plant
• 12 000 hours operation (18 months)
• Significant degradation and corrosion observed later than 200 days from start-up
Moser, P. et al. (2011). "Performance of MEA in a long-term test at the post-combustion
capture pilot plant in Niederaussem“. International Journal of Greenhouse Gas Control 5(4):
620-627.
Moser, P. et al. (2018). “MEA consumption – ALIGN-CCUS: Comparative long-term testing
to answer the open questions”. Poster at GHGT-14, October 2018, Melbourne, Australia.
Degradatio
n products
Iron
concentration
(corrosion) 200
days
Apparatus lab. work
Gamry Multiport corrosion cell (1L) and 700 mL of solvent, N₂-purged
• Data from the potentiostat, temperature sensor, and pH sensor logged to PC
• Data handling and simulation by Gamry software and MS-Excel
Tafel experiment procedure:
• Conditioning at −1.2 V for 10 min, polarization scan from −1.5 to +1.0 V at 2 mV/min scan rate
• Post-run correction for uncompensated solution impedance
• Simulation of current-potential curves
1. Counter electrode (Pt sheet)
2. Work electrode, C1018 steel
3. Reference electrode
(Ag|AgCl)
4. N₂-purge
5. Temperature sensor (Pt100)
• Gamry Reference 600+ potentiostat
• Thermo AC200-S3 bath circulator
• Mettler InLab Reach Pro pH-sensor
– Mettler FiveEasyPlus pH-meter
① ②
③
④ ⑤
TCCS-10 in Trondheim, Norway, 17-19 June 2019 4
Corrosion and Tafel curves (pushing potential – observing current: reaction rate) Corrosion, iron dissolution (anodic reactions)
𝐹𝑒 𝑠 → 𝐹𝑒2+ 𝑎𝑞 + 2𝑒−
𝐹𝑒2+ 𝑎𝑞 → 𝐹𝑒3+ 𝑎𝑞 + 𝑒−
Corrosion, cathodic reactions pH < 4: 2𝐻+ 𝑎𝑞 + 2𝑒− → 𝐻2(𝑔) pH > 5: 2𝐻2𝑂 + 2𝑒− → 𝐻2 𝑔 + 2𝑂𝐻−(𝑎𝑞)
𝑂2 𝑔 + 2𝐻2𝑂 + 4𝑒− → 4𝑂𝐻−(𝑎𝑞)
2𝐻𝐶𝑂3− + 2𝑒− → 𝐻2(𝑔) + 2𝐶𝑂3
2−
Passivation reactions 𝐹𝑒2+ 𝑎𝑞 + 2𝑂𝐻− → 𝐹𝑒(𝑂𝐻)2 (𝑠)
𝐹𝑒2+ 𝑎𝑞 + 𝐶𝑂32− → 𝐹𝑒𝐶𝑂3 (𝑠)
TCCS-10 in Trondheim, Norway, 17-19 June 2019 5
Perez N. (2016) Kinetics of Activation Polarization. In: Electrochemistry and Corrosion Science. Springer, Cham
Passivation
Nesic, S., Postlethwaite, J., Olsen, S., 1996. An Electrochemical Model for
Prediction of Corrosion of Mild Steel in Aqueous Carbon Dioxide Solutions.
Corrosion 52, 280-294
Results: 30 % MEA added 0 | 0.2 | 0.5 mol/mol CO2 versus temperature 25 to 80 °C
TCCS-10 in Trondheim, Norway, 17-19 June 2019 6
-1400
-1200
-1000
-800
-600
-400
-200
0
200
1.0E-061.0E-051.0E-041.0E-031.0E-02
Pote
ntial vs A
g/A
gC
l
Current density
MEA 25 °C #3
MEA 40 °C #2
MEA 60 °C #4
MEA 80 °C #7
-1400
-1200
-1000
-800
-600
-400
-200
0
200
1.0E-061.0E-051.0E-041.0E-031.0E-02
Pote
ntial vs A
g/A
gC
l Current density
MEA-CO2 0.2 25 °C #3
MEA-CO2 0.2 40 °C #2
MEA-CO2 0.2 60 °C #3
MEA-CO2 0.2 80 °C #2
-1400
-1200
-1000
-800
-600
-400
-200
0
200
1.0E-061.0E-051.0E-041.0E-031.0E-02
Pote
ntial vs A
g/A
gC
l
Current density
MEA-CO2 0.5 25 °C #2
MEA-CO2 0.5 40 °C #3
MEA-CO2 0.5 60 °C #2
MEA-CO2 0.5 80 °C #2
Corrosion rate: MEA – CO2 baseline
TCCS-10 in Trondheim, Norway, 17-19 June 2019 7
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
20 30 40 50 60 70 80 90
Corr
osio
n r
ate
Temperature
MEA 30 w% (serie 1) MEA 30 w% (serie 2)
MEA+CO2 (0.2 mol/mol) MEA+CO2 (0.5 mol/mol)
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
8 9 10 11 12 13
Corr
osio
n r
ate
pH
MEA 30 w% (serie 1) MEA 30 w% (serie 2)
MEA+CO2 (0.2 mol/mol) MEA+CO2 (0.5 mol/mol)
Adding organic acids to 0.2 CO2/MEA – pH
TCCS-10 in Trondheim, Norway, 17-19 June 2019 8
8.0
8.5
9.0
9.5
10.0
10.5
11.0
20 °C 40 °C 60 °C 80 °C 100 °C
pH
Temperature
MEA - Formic acid
MEA 30 w% 0.2 CO2
Formic acid, high
8.0
8.5
9.0
9.5
10.0
10.5
11.0
20 °C 40 °C 60 °C 80 °C 100 °Cp
H
Temperature
MEA - Acetic acid
MEA 30 w% 0.2 CO2
Acetic acid, low
Acetic acid, high
8.0
8.5
9.0
9.5
10.0
10.5
11.0
20 °C 40 °C 60 °C 80 °C 100 °C
pH
Temperature
MEA - Oxalic acid
MEA 30 w% 0.2 CO2
Oxalic acid, low
Oxalic acid, high
High level = 0,5 M acid in solvent, aka highest level observed in RWE pilot for acetate. Low
level = 0,09 M
Adding organic acid salts to 0.2 CO2/MEA – pH
TCCS-10 in Trondheim, Norway, 17-19 June 2019 9
8.0
8.5
9.0
9.5
10.0
10.5
11.0
20 °C 40 °C 60 °C 80 °C 100 °C
pH
Temperature
MEA - Formate
Na formate, high
Na formate, low
MEA 30 w% 0.2 CO2
8.0
8.5
9.0
9.5
10.0
10.5
11.0
20 °C 40 °C 60 °C 80 °C 100 °Cp
H
Temperature
MEA - Acetate
Na acetate, high
Na acetate, low
MEA 30 w% 0.2 CO2
8.0
8.5
9.0
9.5
10.0
10.5
11.0
20 °C 40 °C 60 °C 80 °C 100 °C
pH
Temperature
MEA - Oxalate
Na oxalate, low
MEA 30 w% 0.2 CO2
Pilot samples
• Clear sample: Taken a few months after start-up
• Dark sample: Taken just before the first replenishment of solvent
• The dark, degraded sample has significantly lowered pH 8.0
8.5
9.0
9.5
10.0
10.5
11.0
20 °C 30 °C 40 °C 50 °C 60 °C 70 °C 80 °C 90 °C
pH
Temperature
MEA - RWE pilot sample
MEA 30 w% 0.2 CO2 MEA 30 w% 0.2 CO2
MEA 30 w% 0.16 CO2
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Corrosivity from Tafel experiments (80 °C)
• Organic acids added to CO2-loaded MEA results in slightly higher corrosivity
• The clear pilot sample, analyzed to be low in organic acids content, showed highest corrosivity by Tafel experiments
0
1
2
3
4
5
6
Corr
osio
n r
ate
[m
m/y
r]
Reference Lab Acids added Pilot samples
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Corrosivity from Tafel experiments Added sodium acetate high level (25-99 °C)
• pH decrease (less alkaline solvent) at higher temperature
• Corrosion rate increase at higher temperature
TCCS-10 in Trondheim, Norway, 17-19 June 2019 12
0
1
2
3
4
5
8.5
9
9.5
10
10.5
11
20 70 120
Co
rro
sio
n r
ate
[m
m/y
r]
pH
Temperature [°C]
pH C.R.
Conclusion
• Addition of organic acids to CO2-loaded MEA solvent results in lowered pH
• Addition of organic acid salts to CO2-loaded MEA solvent also results in lowered pH, or only a small change in pH
• Corrosivity increases (slightly) upon addition of organic acids or their salts
• Degraded solvent from pilot shows lowered pH versus virgin solvent
• Pilot corrosivity experience (accumulated iron concentration) is not reproduced in lab by Tafel experiments (corrosion rate)
• Large difference in time, scale and metal history
TCCS-10 in Trondheim, Norway, 17-19 June 2019 13
TCCS-10 in Trondheim, Norway, 17-19 June 2019
Acknowledgements
ACT ALIGN CCUS Project No 271501
This project has received funding from RVO (NL), FZJ/PtJ (DE), Gassnova (NO), UEFISCDI (RO), BEIS
(UK) and is cofunded by the European Commission under the Horizon 2020 programme ACT, Grant
Agreement No 691712
www.alignccus.eu
The authors acknowledge Nidal M. Hejazi for his help in performing the Tafel experiments
Corrosivity evaluation
TCCS-10 in Trondheim, Norway, 17-19 June 2019 15
-1200
-1000
-800
-600
-400
-200
0
200
1.0E-06 1.0E-05 1.0E-04 1.0E-03 1.0E-02
Pote
ntial vs A
g/A
gC
l
[A/cm²]
MEA+0.2CO2 +HAc high 80°C
Ru corrected
Ic_H2O (>H2+HO⁻)
Ia_Fe passive
I_total
E_corr, I_corr (simulated)