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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
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Results & Discussion
Experimental rate (γ‐alumina)
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nversion
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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)
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VERSION, X
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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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X
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CONVE
RSION, X
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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
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1.8
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y = ‐2793.4x + 9.0781
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1.2
1.4
ln (k)
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0.6
0.8
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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)
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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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