Presentation given by Hao Liu of the University of Nottingham on "Effective Adsorbents for Establishing Solids Looping as a Next Generation NG PCC Technology" at the UKCCSRC Gas CCS Meeting, University of Sussex, 25 June 2014

1. Effective Adsorbents for Establishing Solids
Looping as a Next Generation NG PCC
Technology
(EP/J020745/1)
Dr Hao Liu
University of Nottingham
Gas CCS Meeting, 25 Jun 2014, Brighton

2. Project Academic Partners
University of Nottingham:
Dr Hao Liu (PI), Prof Colin Snape,
Dr Chenggong Sun, Prof Trevor Drage
University College London:
Prof Z. Xiao Guo
University of Leeds:
Prof Tim Cockerill

3. Project Industrial Partners
Doosan Power Systems (DPS)
E.ON
Parsons Brinckerhoff (PB)
PQ Corporation (PQC)
Worley Parsons (WP)

4. Background (1)
 Recognition: to meet the UK ambitious carbon
emission target by 2050, CCS will have to be
fitted to NGCC power plants.
 NGCC flue gas differs significantly from that
from coal PF power plants: lower CO2, higher O2
and higher gas flow rates (~50%)

5. Table 1: Key features of a supercritical coal-fired power
plant and a NGCC power plant*
Coal NGCC
Net Power (MW) 550 555
Efficiency (%, HHV) 39.3 50.2
Flue gas temperature (0C) 181/57** 106
Flue gas composition
CO2 (vol. %) 13.53 4.04
H2O (vol. %) 15.17 8.67
O2 (vol. %) 2.40 12.09
N2 (vol. %) 68.08 74.32
Ar (vol %) 0.82 0.89
Flue gas flow rate (kg/hr) 2137881 3230636
*DOE/NETL/2010-1397, Rev 2, Nov 2010 **Before FGD/After FGD

6. Background (2)
 Studies show post-combustion carbon capture
(PCC) is the most viable option, both technically
and economically, compared to pre-combustion
and oxy-fuel capture technologies
 Amine scrubbing has well-known problems
 Solid adsorbents looping technology (SALT) –
viable PCC for NGCC plants?
o Supported amine solid adsorbents
o Alkali-promoted inorganic adsorbents

7. CO2, H2O
Flue gas (CO2, O2, N2, H2O etc)
Vent gas (N2, O2) CO2-loaded adsorbents
Regenerated
adsorbents
sweeping gas
(H2O, CO2)
CO2adsorption
CO2desorption
Low T
High T
(SALT)

8. (Circulating Fluidized Bed for SALT)

9. Project Aim
 This project aims to overcome the performance
barriers for implementing the two types of
candidate adsorbent systems, namely the supported
polyamines and co-precipitated potassium oxide, in
solids looping technology for NGCC power plants
 Nottingham and partners have developed various solid
adsorbents e.g. supported amines and alkali-promoted
inorganic adsorbents, nitrogen-enriched carbons for CO2
capture from coal-fired power plant flue gases
 Performance barriers when used for NGCC CO2 capture:
thermal/oxidative stability, degradation due to moisture,
selectivity etc.

10. Research Programme
 WP1 - Development, characterisation and testing of
solid amine adsorbents (UoN & UCL)
 WP2 - Development, testing and characterisation of
potassium-promoted porous adsorbent materials (UoN
& UCL)
 WP3 - Modelling of Surface Adsorption and Advanced
characterisation (UCL & UoN)
 WP4 - Fluidised-bed testing and optimisation of the
most effective adsorbents (UoN)
 WP5 - Conceptual design, process engineering modelling and
techno-economic assessment of SALT for future
demonstration and commercialisation (UoN, UoL)

11. Workplan
Work Package / Tasks Partners Year 1 Year 2 Year 3 Year 4
Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2
WP1: Development, characterisation and testing of solid
amine adsorbents
UoN, UCL
Task 1.1 Preparation and performance-scoping study of
candidate adsorbent materials
UoN
Task 1.2 Optimised preparation for enhanced thermal
oxidative stability
UoN, UCL
Task 1.3 Management of spent materials: PEI rejuvenation UoN, UCL
WP2 Development, testing and characterisation of potassium-
promoted porous adsorbent materials
UoN, UCL
Task 2.1 Preparation, characterisation and testing of
potassium-promoted inorganic adsorbents
UoN, UCL
Task 2.2 The role of flue gas moisture UoN, UCL
WP3 Modelling of Surface Adsorption & Advanced
characterisation
UCL, UoN
Task 3.1 Modelling of surface reaction processes UCL
Task 3.2 Advanced characterisation to support the modelling
studies
UCL, UoN
WP4 Fluidised-bed testing and optimisation of the most
effective adsorbents
UoN
Task 4.1 Scaled-up production of the adsorbents UoN
Task 4.2 Fluidised-bed testing & process development under
simulated NGCC flue gas conditions
UoN
Task 4.3 Fluidised-bed process testing of the optimum
adsorbents with real flue gas streams from natural
gas combustion furnace at a kilowatt-thermal scale
UoN
WP5 Conceptual design, process engineering modelling and
techno-economic assessment of SALT for future
demonstration and commercialisation
UoN, IC
Task 5.1 Conceptual design and process engineering modelling UoN
Task 5.2 Techno-economic assessment IC

12. Progresses so far
 Characterization of PEI-silica
 Bubbling Fluidized Bed Tests
 Degradation of PEI-silica adsorbent (thermal
& oxidative)
 Process simulation (550MWe NGCC power
plant integrated with PEI-SALT PCC)
 Development of new adsorbent materials

13. CHARACTERIZATION OF PEI-SILICA
Batch I (10kg) & Batch II (30kg)

14. Characteristics of the PEI-silica sorbents
polyethylenimine
2
+
Supporting substrates
 material: mesoporous silica
 BET surface area: 250 m2/g
 pore volumes: 1.7 cc/g
 mean pore diameter: 20 nm
PEI impregnation
 Wet impregnation method
 PEI loading: 40 wt%
 Similar to the absorption of CO2 with amine solvents
 The reaction is reversible, allowing for the sorbents to be regenerated by
temperature, vacuum or pressure swing adsorption cycles.
Reaction mechanism
Average particle size ~ 250 µm

15. TGA Characterization
0 20 40 60 80 100
7.5
8.0
8.5
9.0
9.5
10.0
10.5
11.0
11.5
12.0
12.5
Batch I PEI-silica
Batch II PEI-silica
Allometric fit of Batch I
Allometric fit of Batch II
CO2
uptake(wt%)
CO2
concentration (vol%)
5% CO2
 PEI-silica under isothermal condition (70 0C)

16. TGA Characterization
 PEI-silica under isobar condition (Batch II)
20 40 60 80 100 120 140 160
-2
-1
0
1
2
3
4
5
6
7
8
9
10
maximum value of 8.8 wt% at 63o
C
CO2
uptake(wt%)
Temperature (o
C)
minimum value of
-0.05 wt% at 122o
C
original PEI (batch II)
5%CO2
0.1o
C heating rate

17. BUBBLING FLUIDIZED BED TESTS OF
PEI-SILICA
@kg-sorbent scale

18. moisture
saturator
108mm
67mm
0.5m1.2m
Bubbling Fluidized Bed (BFB) reactor

19. CO2 Capture with NGCC Flue Gas - test conditions

20. Effect of CO2 concentration in flue gas
1 2 3
0
2
4
6
8
10
262524
232220
262524
2322
20
262524
2322 15% CO2
5% CO2
BreakthroughEqu.-Desorption
Capacities(wt%)
Equ.-Adsorption
20
Cycle ID#
Flue gas:
CO2, O2,
H2O,
balanced
with N2
Potential in low CO2-containing gas mixture application

21. Comparison of capacities for PC and NGCC flue gases
Flue gas 1: from coal fired power plants (CO2 15%, O2 4%)
Flue gas 2: from Natural Gas Combined Cycle (NGCC) power plants (CO2 5% and O2 12%)
No obvious oxidative
degradation has
been found even if
O2 level is increased
to 12% for 7 cycles
50 52 54 56 58 60
0
2
4
6
8
10
12
0
2
4
6
8
10
12
simulated flue
gas (NGCC)
simulated flue
gas (PC)
by adsorption
by desorption
breakthrough
Capacities(wt%)
Cycle ID
simulated flue
gas (NGCC)
Flue gases:
CO2, O2, H2O,
balanced with N2
Wenbin Zhang, Hao Liu, Chenggong Sun, Trevor C. Drage, Colin E. Snape: Performance of
polyethyleneimine-silica adsorbent for post-combustion CO2 capture in a bubbling fluidized bed. Chemical
Engineering journal, 251 (2014): 293-303

22. 0 10 20 30 40 50 60
0.4
0.5
0.6
0.7
0.8
0.9
1.0
1.1
Test serial 1
Test serial 2
NormalizedCO2
adsorptioncapacityq/q0
Cycle number
Degradation of PEI-silica adsorbents over 60 cycles tested
with the BFB reactor
With moisture present
With moisture present
Without moisture
present

23. Surface morphology change of PEI-silica adsorbent
after 20 dry cycles of adsorption/desorption

24. DEGRADATION OF PEI-SILICA ADSORBENT
(thermal & oxidative)

25. 0 10 20 30 40 50
7.0
7.5
8.0
8.5
9.0
9.5
10.0
10.5
11.0
11.5
CO2
uptake(wt%)
Cycle No#
Batch II, under 5% CO2
Batch II, under 15% CO2
TGA characterization on degradation
- Cyclic performance with different CO2 partial pressures @70 0C/130 0C

26. 0 10 20 30 40 50
5.5
6.0
6.5
7.0
7.5
8.0
8.5
9.0
9.5
relative loss 32%
CO2
capacity(wt%)
Cycle Number
desorption at 120o
C
desorption at 130o
C
relative loss 13%
TGA characterization on degradation
- Cyclic performance with different desorption temperatures
(15% CO2/N2 balance, Batch I, adsorption @70 0C)

27. TGA characterization on degradation
- Oxidative degradation of PEI-silica adsorbent
Oxidized samples of PEI-silica (Batch I) prepared by
drying/oxidizing in an air-ventilated drying oven @ca. 70 - 80oC
for 1, 2, 3, 4, 5, 6, 10 days
Appearance after TGA tests
CO2 concentration: 5 vol%
Adsorption/desorption @ 70oC/130oC
Appearance before TGA tests

28. Characterisation of oxidative degradation by Raman Spectroscopy
Exposure of supported PEI adsorbents to air/oxygen at moderate temperatures can lead to
significant oxidative degradation as highlighted by the formation of oxime (C=N-OH) and other
oxygen-containing functionalities.
The loss of active amine groups due to oxidation is consistent with the decreased adsorption
capacity observed for the supported PEI adsorbents in NGCC flue gas conditions.

29. PROCESS SIMULATION
- 550MWe NGCC power plant integrated
with PEI-SALT PCC

30. Process simulation: Integration of PEI-SALT PCC
into a 550MWe NGCC power plant

31. Conceptual design of
PEI-Silica SALT system
o CFB riser as gas-solid
contactor and CO2 adsorber
o BFB as desorber to
regenerate solid sorbents
o Loop seal to return
sorbents back to CFB with
integrated heat exchanger
for heat recovery
o Cyclone to separate solid
sorbents from flue gas
o A mixture of CO2 and
steam is proposed as the
stripping gas

32. Comparison of power losses for NGCC power plants
with and without CO2 capture
f
comcapaug
f
e
c
Q
EEEE
Q
E −−−
==η
cηηη −=∆Efficiency penalty:
Plant efficiency with PCC
and CO2 compression
Ee: net power output
Qf: thermal heat input by fuel
Eg: gross power output from turbines
Eau: auxiliary load
Ecap: electrical energy required by CCS unit
Ecom: electrical energy required to compress the CO2 product

33. w/o CCS* MEA* PEI-silica
SALT
NGCC power plant net
efficiency (%)
55.7 47.5 50.3
Required Regeneration Heat
(GJ/tonne-CO2)
N/A 3.7 2.2
All efficiencies are LHV based. Sensible heat recovery ratio: 90%
Comparisons of power plant efficiencies with and
without CCS and regeneration heat requirements
* NETL: Cost and performance baseline for fossil energy plants, Volume 1: bituminous coal and
natural gas to electricity. Revision 2, November 2010, DOE/NETL-2010/1397
raddesp
w
r HTTC
q
Q ∆+−= )(
1
,
Regeneration heat:
Qr is the regeneration heat (kJ/kg-CO2 adsorbed)
Tad and Tde are the temperatures of adsorption and desorption
respectively (oC)
qw is the working capacity of the adsorbent (wt%)
Cp,s is the specific heat capacity of the adsorbent (kJ/kg.K)
∆Hr is the heat of adsorption (kJ/kg-CO2 adsorbed)

34. Development of new adsorbent materials
- New PEI-silica adsorbents & alkali metal
carbonate-based adsorbents

35. Sample
CO2 uptake (wt.%)
5% 15% 100%
A 10.85 11.84 13.03
B 11.05 12.92 14.22
C 10.58 12.06 14.50
D 10.23 10.48 12.36
E 8.40 8.62 11.84
F 7.95 7.98
G 9.05 11.48
Batch I (TGA@70o
C) 7.72 9.10 10.80
Batch II(TGA@70o
C) 9.13 10.34 12.00
Adsorption capacity of new PEI-silica sorbents (TGA@75 oC)
Further optimization & characterisation are ongoing!

36. K2CO3-based sorbents
 K2CO3 –based solid sorbent is very promising due to:
1) Good adsorption/desorption temperatures;
2) High CO2 capacity, good kinetics;
3) Presence of moisture in the flue gas benefits the CO2 adsorption
performance:
Adsorption: 𝐾𝐾2 𝐶𝐶𝑂𝑂3(s) +𝑯𝑯𝟐𝟐 𝑶𝑶(𝑔𝑔) + 𝐶𝐶𝐶𝐶2(𝑔𝑔) → 2𝐾𝐾𝐾𝐾𝐾𝐾𝑂𝑂3 (s) + exothermic
Desorption:2𝐾𝐾𝐾𝐾𝐾𝐾𝑂𝑂3 (s) → 𝐾𝐾2 𝐶𝐶𝑂𝑂3(s) +𝐻𝐻2 𝑂𝑂 𝑔𝑔 + 𝐶𝐶𝐶𝐶2 𝑔𝑔 + endothermic
 The main challenges: how to maximise the loading of potassium
to further boost CO2 uptake capacity and kinetics without
sacrificing significant loss of the surface area and to reduce
regeneration temperatures to well below 200 oC

37. • Procedures:
Trial of K2CO3/AC in a fixed-bed reactor
Preparation
Calcination
Fixed bed testingDrying oven
Conditions:
300OC with a
N2 flow
atmosphere
Impregnation:
K2CO3+AC
Magnetic
Stirring
Adsorpt. temp: 60OC
Desorpt. temp: 150OC
Ambient pressure
15%CO2+85%N2 (Dry
basis, with moisture
saturated @50 0C)
On-going

38. OTHER TASKS
- UCL & UoL

39. - Fundamental bonding and electronic interaction mechanisms of
gaseous species adsorbed on different surface sites, e.g. silica
and graphitic carbon
Task3.2 Advanced characterisations of solid sorbents
for CO2 capture (UCL with UoN)
- Sorbent stability;
- Recyclability & regeneration;
Task3.1 Modelling of surface reaction processes (UCL)
Task 3.1 was scheduled to start at the beginning of the year 2014 and
Task 3.2 was scheduled to start on 1 Oct 2014.
UCL’s RA had been recruited recently and just started the modelling
Task 3.1
Task 3.2 will start as scheduled.

40. TASK 5.2 How will a full-scale SALT perform in
comparison to other CCS technologies?
Environmental parameters:
Techno-economic parameters:
• Overall CO2 capture effectiveness
• Lifecycle energy and GHG emissions analysis
• Rates of use of consumables
• Waste / by-product production rates
• Investment costs
• Operating costs
• Levelised energy production costs for selected operational scenarios
(e.g. base load, peaking plant)
(Scheduled to be Carried out by UoL from Jan 2015)

41. Use integrated CCS
assessment system
developed over >5 years
Currently deals with amine, and
calcium
looping capture technologies
Developing new process model
elements for SALT drawing on UoN
lab results (and literature / expert
data)
Operational scenarios include
peaking
operation, ‘base-load’, FOAK only
and fleet roll out.

42. Conclusions & Future Work
 The project is largely on track in terms of completing the
scheduled tasks and significant progresses have been made:
 High performance of PEI-silica adsorbent for CO2 capture from NGCC flue
gas has been demonstrated in a laboratory-scale BFB reactor with kg-
scale adsorbent;
 Process simulation on a 550MWe NGCC plant integrated with a PCC unit
has shown that application of PEI-silica adsorbent can save 2.8% in
efficiency penalty compared to MEA, owing to the much lower regeneration
heat requirement;
 New sorbent materials have been prepared, some with much higher CO2
uptakes under NGCC flue gas conditions;
 Thermal and oxidative degradations of PEI-silica have been characterised.
 Future work include
To optimise/test the newly developed sorbent materials;
To further develop/test K2CO3-based sorbent materials;
To investigate the rejuvenation of the degradated PEI-silica and strategies to
prevent degradation of PEI-silica;
To model surface reaction processes;
To conduct techno-economic assessment of SALT etc.

43. ACKNOWLEDGEMENTS
• The financial support of the UK EPSRC (EP/J020745/1)
• The contributions of the project investigators and
researchers: Prof Colin Snape, Dr Chenggong Sun, Prof
Trevor Drage, Prof Z. Xiao Guo, Prof Tim Cockerill, Dr
Wenbin Zhang, Dr Nannan Sun, Miss Jingjing Liu, Mr
Yuan Sun, etc.
• The contributions of the project industrial partners
Thank you for listening!
Any questions?
Contact email:
Liu.hao@nottingham.ac.uk