Electrochemically-Mediated Sorbent Regeneration

in CO2 Scrubbing Processes (FE0026489)

T. Alan Hatton

Ralph Landau Professor of Chemical Engineering

Director, David H. Koch School of Chemical Engineering Practice

Co-Director, MITEI Low Carbon Energy Center for CCUS

Massachusetts Institute of Technology, Cambridge MA 02139

Project Overview

Award Name: Electrochemically-Mediated Sorbent Regeneration in CO2 Scrubbing Processes

(FE0026489)

Funding:

DOE $1,202,052

Cost Share $ 310,601

Total $1,512,653

Project Period:August 1, 2017 – July 31, 2020

Project PIs: T. Alan Hatton, Howard Herzog

DOE Project Manager: Ted McMahon

Overall Project Objectives: Develop, characterize and implement electrochemically mediated

sorbent regeneration and CO2 release in amine scrubbing processes

2

Feed Gas

Lean Gas

CO2

Cooling Water

ProcessSteam

Amine

Amine + CO2

AbsorberT<60 °C

DesorberT>110 °C

Benchmark CO2 Capture Technology: Thermal Amine

3

HeatCool

CO2 Amine Amine/CO2 Complex

CO2

Amine

Electrochemically Mediated Amine Regeneration (EMAR)

4Plug and Play Efficient High Pressure Release✓ ✓ ✓

CO2 Amine Amine/CO2 Complex

Add M++

M2+

CO2

Amine/Meta

l

Complex

Remove M++

+-

Metal

Anode

Metal

Cathode

M2+

Feed Gas

Lean Gas

CO2

Amine

Amine+ CO2

AbsorberT<60 °C

DesorberT<60 °C

P = 5–10 bar

Feed Gas

Lean Gas

CO2

Cooling Water

ProcessSteam

Amine

Amine + CO2

AbsorberT<60 °C

DesorberT>110 °C

Electrochemically Mediated Amine Regeneration (EMAR)

5

+-

Feed Gas

Lean Gas

CO2

Amine

Amine+ CO2

AbsorberT<60 °C

DesorberT<60 °C

EMAR Anatomy

6

• Cost

• Electrochemical transition happens within the aqueous stability window

• Metal ion has sufficiently strong binding to displace CO2 (amine specific!)

• Solubility

• Electrochemical kinetics

Se

lec

tio

n

Cri

teri

a

Effect of Copper on CO2 Loading

7

EDATETAAEEA

2mols CO

mols N

2mols Cu4

mols N

T = 50oC , [Am] = 2N , 1M KNO3 , yCO2 = 0.15

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0 0.2 0.4 0.6 0.8 1

CO

2 L

oadin

g,

Copper Loading,

EDA

TETA

AEEA

0.0

0.50

1.0

1.5

2.0

2.5

EDA AEEA TETA

Moles of CO2 Released per Moles of Copper Added

2.04 1.95 1.84

M.C. Stern, F. Simeon, H. Herzog, T.A. Hatton, Energy and Environmental Science. 2013

Thermodynamic Cycle

Carnot Cycle EMAR Cycle

8

Volume, V

Pre

ssu

re, P

State of Charge, Q (xCu)

Op

en C

ircu

it P

ote

nti

al, E

Thermodynamic Cycle

9Feed Gas

Lean Gas

CO2

Amine

Amine+ CO2

Thermodynamic Cycle

10Feed Gas

Lean Gas

CO2

Amine

Amine+ CO2 1

2

3

1

2

3

Thermodynamic Cycle

11Feed Gas

Lean Gas

CO2

Amine

Amine+ CO2 1

2

3

1

2

3

Total Work for EMAR Cell

12

0 0.2 0.4 0.6 0.8 1

Copper Loading Shift, xCu

0

10

20

30

40

50

Wo

rk (

kJ/m

ol)

EMAR Cell

Pump

Compressor

Total

Thermodynamic Results

Feed Gas

Lean GasCO2

13Thermodynamic minimum work of CO2 capture and compression to 150 bar of a 15% CO2 stream

Thermodynamic Results

Feed Gas

Lean GasCO2

14Thermodynamic minimum work of CO2 capture and compression to 150 bar of a 15% CO2 stream

Lowest

Capital

Expensive

Absorber

Expensive

Compressor

Anatomy of EMAR Cell

15

Scaling Up Electrochemical Systems

16

Experimental Demonstration of CO2 Release

17Liquid flow rate = 10mL/min

Process Automation

18

CO2 Release in Response to Applied Current

19

0.0

2.0

4.0

6.0

8.0

10.0

0 0.1 0.2 0.3 0.4 0.5 0.6

CO

2 A

bsorb

ed (

mL/m

in)

Current (A)

Theoretical Max

Experiment

Cyclic Stability of EMAR Operations

20

Series Geometry

21

Series geometry

high voltage

low current

Anode

Ca

thode

V

stack= nV

cell

I

stack= I

cell

P = nV

cellI

cell

Copper Loading Effect on Current Density

22

Anode (+)

Inlet

Cathode (-)

Inlet

[(CuIIAm2)2+]

(mol/L)]

Copper Loading Effect on Current Density

23

Anode (+)

Inlet

Cathode (-)

Inlet

[(CuIIAm2)2+]

(mol/L)]

Series Experiments – Current Density

Theoretical Current Density (A/m2) Experimental Current Density (A/m2)

24

• Change in the anodic reaction as CO2 loading drops or increased advection (diminishing

boundary layer resistance) caused by CO2 production in the anode.

• Parasitic side reactions (especially in the cathode) (e.g.,. formation of CuO).

EMAR Advantages

Electrochemical Thermal

Energy Consumption 15 – 40 kJ/mole 50-70 kJ/mole

Low temperature

OperationYes No

Ease of Deployment Plug-and-Play Expensive Retrofit

High Pressure

DesorptionYes No

Overpotentials for Electrochemical Reactions

26

0 exp exp2 2

)(1F F

RT Ri i

T

In absence of CO2, formation of EDA complex does not significantly

hinder Cu deposition and dissolution. EDA Stabilizes Cu2+ in solution

Overpotentials for Electrochemical Reactions

27

In presence of CO2, kinetics are significantly hindered. However, chlorides were

observed to improve performance significantly.

EMAR Cathode

ideally operates in

absence of CO2

Effects of Supporting Electrolyte on Copper Reduction

28

NaCl NaNO3

Project Risks and Mitigation Strategies

29

Technical Risks Probability Impact Risk Mitigation

CO2 sorbents and metal ion

systems unsuccessful

Medium Low Wide range of candidate sorbents

available. Initial results are

promising

Electrochemical cell models low in

fidelity and do not permit

optimization

Moderate Low Complexity of underlying

mechanisms in electrochemical

cell presents risk for modeling.

Parametric experiments will

generate sufficient data for

empirical optimization.

Process found to be too sensitive

for long-term operations and

disturbances

Moderate Moderate Preliminary testing is encouraging.

Degradation of electrodes or

sorbents possible, but can be

mitigated through design of

electrode configurations

Resource and Management Risks

30

Resource Risks Probability Impact Risk Mitigation

Cost of bench-scale system after

optimization more expensive than

planned

Low Low Most of the components of the

system have been procured and

operated in previous work, but the

optimized system might involve

more expensive equipment,

especially for automation.

Management Risks Probability Impact Risk Mitigation

Process performance reaches a

plateau that does not satisfy DOE

research goals

Moderate High The progress reports will allow the

project team to evaluate the

performance of the process and

determine whether it is possible to

explore new dimensions for

performance improvements.

Experimental Design and Work Plan

31

Task SubTask

Evaluate and Test CO2 Sorbents and Metal Ions for

Electrochemical Regeneration

• Identify and Shortlist Candidate Molecules

• Thermodynamic and Kinetic Experiments on Candidate

Molecules

• Cycling Stability Experiments on Candidate Molecules

Process Modeling and Cost Estimation • Develop process model and evaluate pressure effects

• Develop cost estimates

Electrochemical Cell Model Development • Establish kinetics and mass transfer model

• Model validation

Flow Channel Design and Optimization • Model-aided design of candidate flow channels

• Construction and testing of candidate flow channel

configurations

Optimization of Electrode Configuration and Cell

Architecture

• Evaluation of different electrode materials

• Evaluation of cell architectures

Evaluation of Optimized Chemistries and Cell

Designs

• Design and build instrumented lab-scale apparatus

• Testing of candidate systems under wide operating

conditions

• Stability testing

Budget

Period

1

2

3

Acknowledgements

3232

Mike Stern Aly Eltayeb Miao WangRyan Shaw

33