Degradation Potential of Aqueous and Water-Lean MEA Karen K. Hister - - PowerPoint PPT Presentation

Degradation Potential of Aqueous and Water-Lean MEA

Karen K. Høisæter and Hanna K. Knuutila

TCCS-10 Trondheim, 17.-19. June 2019

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Outline

Introduction Experimental Results Conclusion

• MEA + water
• MEA + TEG/water
• Further work
• Solution preparation
• Methodology

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Thermal degradation With CO2 Without CO2

• 1. Introduction

Solvent degradation

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• 1. Introduction

Solvent degradation

Primary and secondary amines  Carbamate polymerization Degradation dependent on:

• Temperature
• CO2 loading
• Initial MEA concentration

Tertiary amines  Other mechanisms

Davies et al., 2009

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• 1. Introduction

Motivation Aqueous amines Water lean solvents

30-40wt% amine Amine and

• rganic

solvents

• 2. Experimental

Solution preparation

MEA CO2 Water MEA CO2 Water TEG

Triethylene glycol (TEG)

Two parallels extracted each week

• Experiments

ran for 5 weeks

• 2. Experimental

Methodology

Stainless steel cylinders Placed in an oven at 135°C

• 8 g solution
• Flushed with N2

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• Amine titration  Remaining amine concentration
• TOC  CO2 concentration
• ICP-MS  Metals in solutions
• LC-MS  degradation products
• 2. Experimental

Analytical methods

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α = 0.5

• 3. Results

Thermal degradation of MEA in water

• Varying ratios of MEA in water
• Previously thought to increase

degradation:

– Increased loading – Increased MEA concentration

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• 3. Results

Degradation results of MEA in water

0.65 0.70 0.75 0.80 0.85 0.90 0.95 1.00

1 2 3 4 5

Relative amount of amine

Weeks

100 mol% 8 mol%

Different ratios of MEA in water, loaded with 1.77 molCO2/kg solution MEA in water

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• 3. Results

Degradation results of MEA in water

0.65 0.70 0.75 0.80 0.85 0.90 0.95 1.00

1 2 3 4 5

Relative amount of amine

Weeks

100 mol% 73 mol% 41 mol% 23 mol% 11 mol% 8 mol%

Different ratios of MEA in water, loaded with 1.77 molCO2/kg solution

Δ 1.1 mol/kg Δ 1.0 mol/kg Δ 0.93 mol/kg Δ 0.81 mol/kg Δ 0.85 mol/kg Δ 1.1 mol/kg

MEA in water

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• Varying ratios of TEG in water, and

constantly 5 Molal MEA (α = 0.5)

• Triethylene glycol, TEG:
• 3. Results

Degradation results of MEA in water/TEG

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• 3. Results

Degradation results of MEA in water/TEG

0.4 0.5 0.6 0.7 0.8 0.9 1.0 1 2 3 4 5

Relative amount of amine Week 0 mol% 100 mol% Different ratios of TEG in water, with 5 Molal loaded MEA TEG in water

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• 3. Results

Degradation results of MEA in water/TEG

0.4 0.5 0.6 0.7 0.8 0.9 1.0 1 2 3 4 5

Relative amount of amine Week 0 mol% 5 mol% 20 mol% 50 mol% 80 mol% 100 mol% Different ratios of TEG in water, with 5 Molal loaded MEA TEG in water

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• 3. Results

Degradation results of MEA in water/TEG

Water stabilizes protons needed for carbamate polymerization reaction TEG leads in different degradation mechanism Degradation products of TEG enhances the carbamate polymerization reaction pKa 14.06 pKa 14.00

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• MEA and water concentrations do not seem to influence thermal

degradation significantly.

• Replacing water with TEG results in higher thermal degradation of

MEA.

• Further analysis needs to be conducted to look into the effect of

TEG on the degradation of MEA.

• 4. Conclusions

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• 4. Conclusions

Further work

MEA in water, with constant absolute amount of CO2 MEA in different ratios of 0-100% TEG and water Various amines in 0% and 50% TEG in water Various organic solvents, both pure and with 5 Molal MEA (loaded).

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Thank you for the attention!

Questions?