corrosivity of degraded mea solvent and fresh …...2019/06/19 · tccs-10 in trondheim, norway,...

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)


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


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)


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


-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


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


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


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


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


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


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

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

http://www.alignccus.eu/

Corrosivity evaluation


-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)

corrosivity of degraded mea solvent and fresh …...2019/06/19 · tccs-10 in trondheim, norway,...

Documents