Kinetics of Catalytic Desorption of CO from Monoethanolamineof CO2 from Monoethanolamine

(MEA)(MEA)Ananda Akachuku

Anima Osei1, Benjamin Decardi‐Nelson1, Wayuta Srisang1, Fatima Pouryousefi1, Ibrahim Hussaldiem1 and Dr. Raphael Idem1*

Clean Energy Technologies Research Institute1

Faculty of Engineering and Applied Science University of Reginay g

13rd Post Combustion CO2 Capture (PCCC3) Conference,  2015 September  08‐11

OutlineOutline • Introduction

• Objective

• Theory and Experimental 

• Result & Discussion

• Conclusion

• Acknowledgement2

IntroductionOne of the major issues facing PCCC is the high energy cost.

In order to tackle this high cost Idem and Shi et al (2011)introduced the addition of catalyst into the absorber desorberintroduced the addition of catalyst into the absorber‐desorbersystem.

However, in order to effectively design a catalytic absorption‐d ti i b d CO l t th ki ti h hdesorption amine based CO2 plant the kinetic phenomena has to be known.

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ObjectivesObjectives

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TheoryTheory

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TheoryTheory

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Theory The following reactions may take place when CO2 is absorbed or desorbed from aqueous MEA.

Equilibrium Reactions

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TheoryTheoryNon‐catalytic CO2 desorption reaction 

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TheoryTheoryAdditi f C t l t t th d b l (id d Shi t l (2011)• Addition of Catalyst to the desorber column (idem and Shi et al (2011) 

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TheoryTheory Catalytic CO2 desorption reaction 

The addition of bronstedacid catalyst HZSM‐5 assistin carbamate breakdownby donating proton

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OHMEACOOHMEACOO 223

Idem et al (2011)

ExperimentalExperimental

Chemicals Manufactures 

MEA

CO2 and N2 Praxair  Inc., 99% purity

Zeochem, USA

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Intrinsic Kinetic DataIntrinsic Kinetic Data

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Intrinsic Kinetic DataIntrinsic Kinetic Data

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Process ParametersProcess ParametersP tParameters 

Solvent  MEA

Inlet gas flow rate 30 SLPMInlet gas flow rate   30 SLPM

Inlet Composition  15%

Catalyst  γ‐alumina and H‐ZSM‐5 (50‐300g)

Amine (MEA) Concentration 5M

Amine (MEA) Flow rate 60 mol/min

Temperature variation  358.15‐ 388.15 (K)p ( )

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Packed Bed reactor ( Packing material)Packed Bed reactor ( Packing material)

CO2CO2

MEAMEA

15Catalyst weight: 50g, 100g , 150g , 200g , 250g , 300g

Results & Discussion

Experimental rate (γ‐alumina)

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70

30

40

50

nversion

, X

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Con

00 0.5 1 1.5 2 2.5 3 3.5 4 4.5

W/FA,o (g.catalyst.min/mol)

358.15 K 368.15 K 378.15 K 388.15 K16

Results & Discussion

Experimental rate (HZSM-5)

Results & Discussion

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Experimental rate (HZSM-5)

30

40

50

VERSION, X

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20

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CONV

00 0.5 1 1.5 2 2.5 3 3.5 4 4.5

W/Fa,o (g.catalyst.min/mol

358.15 K 368.15 K 378.15 K 388.15 K

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Results & DiscussionResults & Discussion

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25

30

35

X

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20

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CONVE

RSION, X

5

10

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00 0.5 1 1.5 2 2.5 3 3.5 4 4.5

W/Fa,o (g.catalyst.min/mol

gamma alumina  H‐ZSM 5

Mechanistic ModelMechanistic Model

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Mechanistic ModelMechanistic Model Langmuir–Hinshelwood–Hougen–Watson (LHHW)Dual site  (H‐ZSM 5)

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Mechanistic ModelMechanistic Model Langmuir Hinshelwood Dual site (LHW) g

Rate Determining Step (RDS) 

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Mechanistic ModelMechanistic Model Rate equations

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Mechanistic ModelMechanistic Model Catalytic Rate equations

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Power Law ModelPower Law ModelArrhenius plot

1/T Vs. ln k (MEA‐γ‐alumina)

Arrhenius plot

1.6

1.8

2

y = ‐2793.4x + 9.0781

1

1.2

1.4

ln (k)

0 2

0.4

0.6

0.8

0

0.2

0.00255 0.0026 0.00265 0.0027 0.00275 0.0028 0.002851/T 24

Power Law Modelo e a odeArrhenius plot

2.5

1/T Vs. ln K (MEA‐HZSM‐5)

2

y = ‐1961.5x + 7.0065R² = 0.9142

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1.5

ln(K)

0.5

00.00255 0.0026 0.00265 0.0027 0.00275 0.0028 0.00285

1/T 25

Parameter EstimationParameter Power law model 

(γ‐alumina)

Power law model 

(HZSM‐5)(γ ) ( )

ko

E(J/mol)

n 1.5 0.5

Rate constant , k

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AAD (%)  < 12

DiscussionDiscussion

lower frequency of occurrence 

Higher frequency of occurrence

1.5 0.5

of occurrence 

rate of reaction depends  on the concentration of

rate of reaction  depends  on the concentration of

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concentration of chemical species to a large extent

concentration of chemical species to a less extent

DiscussionDiscussion

Endothermic reaction 

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Reaction pathway 

Parameter EstimationParameter Estimation

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ConclusionsConclusions

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Future WorkFuture WorkV lid t d h i ti d l• Validate and propose more mechanistic models

• Effect of catalyst weight and temperature on blended amine solvents MEA MDEA and MEA DEABMEA‐MDEA and MEA‐DEAB

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ReferencesReferencesC l M (1968) Ki ti f b t f ti d• Caplow, M. (1968). Kinetics of carbamate formation andbreakdown. Journal of the American Chemical Society, 90(24), 6795‐6803.

• Froment, G.F., Bischoff, K.B., (1990). Chemical Reactor Analysis andDesign, second ed. Wiley, New York.

• Raphael Idem, Huancong Shi, Don GELOWITZ, PaitoonTontiwachwuthikul., (2011) Catalytic method and apparatus for

ti t f i i tseparating a gaseous component from an incoming gas stream.

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A k l d tAcknowledgement

Clean Energy Technologies Research Institute

Natural Sciences and Engineering g gResearch Council of Canada

Faculty of Graduate Studies and Research(FGSR), University of Regina

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(FGSR), University of Regina

THANK YOU

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Mechanistic ModelMechanistic Model

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