An Update on Gas CCS Project: Effective Adsorbents for Establishing Solids Looping as a Next Generation NG PCC Technology - presentation by Colin Snape in the Natural Gas CCS session at the UKCCSRC Cardiff Biannual Meeting, 10-11 September 2014

1. An Update on Gas CCS Project: Effective Adsorbents for Establishing Solids Looping as a Next Generation NG PCC Technology (EP/J020745/1) Professor Colin Snape University of Nottingham UK CCSRC Meeting, Cardiff, 10 – 11 Sept 2014

2. Project Academic Partners University of Nottingham: Dr Hao Liu (PI), Prof Colin Snape, Dr Chenggong Sun 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, first UK demo

Solid adsorbents looping technology (SALT) – viable PCC for NGCC plants?
o
Supported amine solid adsorbents
o
Alkali-based inorganic adsorbents, carbonate- bicarbonate cycle.

7. CO2, H2O
Flue gas (CO2, O2, N2, H2O etc)
Vent gas (N2, O2)
CO2-loaded adsorbents
Regenerated adsorbents
sweeping gas (H2O, CO2)
CO2 adsorption
CO2 desorption
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. Project Specific Objectives (1)

To overcome the following major specific challenges:

To examine and enhance the oxidative and/or hydrolytic stability of supported / immobilised polyamine adsorbents and hence to identify efficient and cost-effective management strategies for spent materials.

To optimise the formulation and preparation of the potassium carbonate co-precipitated sorbents for improved working capacity, reaction kinetics and regeneration behaviour at lower temperatures.

To gain comprehensive understanding of to what degree and how different flue gas conditions, particularly oxygen and moisture, can impact the overall performance of adsorbent materials and related techno-economic performance of a solid looping process.

11. Project Specific Objectives (2)

To produce kg quantities of the optimum adsorbent materials and then demonstrate their performance over repeated adsorption/desorption cycles and to establish the optimal process thermodynamics in fluidized bed testing.

To investigate a novel rejuvenation strategy for oxidised PEIs involving low temperature hydrogenation.

To conduct techno-economic studies to assess the cost advantages of the solids looping technology for NGCC power plants over amine scrubbing based on the improved adsorbent performance and optimised process configuration achieved in the project.

12. 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)

13. Progress so far

Characterization and performance of “standard” PEI-silica

Bubbling Fluidized Bed Tests

Degradation of PEI-silica adsorbent (thermal & oxidative)

Process simulation (550nMWe NGCC power plant integrated with PEI-SALT PCC)

Development of new adsorbent materials

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

15. 00.511.522.52030405060708090100Temperature oC CO2 uptake (mmol g-1) Silica-PEITemplated MF resinSugar-carbazole carbonUF resin carbon
(ii)
(iv)
(iii)
(v)
Silica-PEI and Carbon Adsorbents ca. 2009
(i)
Drage T.C. Blackman J.M. Pevida C. and Snape C.E. 2009. Energy & Fuels, 23, 2790–2796. (ii) Drage T.C., Arenillas A., Smith K.M. And Snape C.E. Micropor. & Mesopor. Mats. 2008, 116, 504-512. (iii) Drage T.C., Pevida C. and Snape C.E. Carbon, 2008, 46, 1464-1474. (iv) Drage T.C., Arenillas A., Smith K.M., Pevida C., Piippo S. and Snape C.E., 2007. Fuel 86, 22-31. (v) Arenillas A., Drage T.C., Smith K. and Snape C.E., 2005. J. Anal. and Appl. Pyrolysis, 74, 298-306.

16. Characteristics of the standard 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

17. TGA Characterization
0204060801007.58.08.59.09.510.010.511.011.512.012.5 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)

18. TGA Characterization

PEI-silica under isobar condition (Batch II)
20406080100120140160-2-1012345678910maximum value of 8.8 wt% at 63oC CO2 uptake (wt%) Temperature (oC) minimum value of -0.05 wt% at 122oCoriginal PEI (batch II) 5% CO20.1oC heating rate

19. 203040506070801.01.11.21.31.41.51.61.71.81.92.02.1 Specific Heat Cp (J/g.oC) Temperature (oC) product I product II
Specific heat measurements of PEI-silica adsorbent
specific Heat (J/g.K)
1.5-1.9, by our measurements
1.25, by Pirngruber (2013)
1.926, by Yang (2009)
0.8-1.3, by Sjostrom (2011)
Pirngruber, G. D. et al., International Journal of Greenhouse Gas Control, 14 (2013): 74-83
Yang, W. C. et al., Ind. Eng. Chem. Res., 48(2009): 341-351
Sjostrom, S. et al., Energy Procedia, 4(2011): 1584-1592

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

21. Regeneration Secondary reactions in dry CO2 C/S (thousands) 246810121416300290280Binding Energy (eV) 285.4287.9 C 1s 1s246810121416300290280Binding 1s468101214410408406404402400398396394392Binding Energy (eV) C/S (thousands) 400.0400.4 N 1s468101214410408406404402400398396394392Binding 468101214410408406404402400398396394392Binding 1sElement Binding Energy Intensity % Assignment Structure Reference Si 103.9 20 SiO2 - inorganic support SiO2 [3] O 532.0 29 SiO2 - inorganic support. Good agreement between the ratio of Si and O2 SiO2 [3] 530.8 1.5 Close match to urea / polyurea NNO [4] C 287.9 5.3 Carbonyl carbon from urea fragment NCNO [4] 285.4 30.2 Matches carbon skeleton of polyethylenimine CCN [4] N 400.4 1.8 Good match to nitrogen adjacent to a carbonyl group - such as polyurea NNOR [4] 400.0 10.5 Matches nitrogen of polyethylenimine CCN [4]

13C NMR, XPS, elemental analysis, DRIFT used to identify secondary reaction product.

Reaction proposed to result in the formation of a urea type linkage.
Drage et al. (2008) Microporous and Mesoporous Materials doi:10.1016/j.micromeso.2008.05.009
02468100246810121416Regeneration time (Hrs): volumetric flow rate 200 mlmin-1 Equilibrium CO2 uptake at 75oC (wt.% - - - - PEI 600MM - 140 °C CO2PEI 423MM - 135 °C CO2PEI 1800MM - 140 °C CO2PEI 600MM - 140 °C N2

22. 010203040505.56.06.57.07.58.08.59.09.5relative loss 32% CO2 capacity (wt%) Cycle Number desorption at 120oC desorption at 130oCrelative loss 13%
TGA Cyclic performance with different desorption temperatures (15% CO2, Batch I, adsorption @70 0C)

23. 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

24. TGA Cyclic performance of oxidatively degraded samples
12345012345678910 CO2 capacity (wt%)Cycle No. original PEI-silica oxidized sample (4 days) oxidized sample (10 days)
CO2 concentration: 15 vol% Adsorption/desorption @ 70oC/130oC

25. 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. .

26. PEI reductive rejuvenation by - Hypy/autoclave
Oxidised PEI-silica
Hypy/autoclave + Catalyst
Rejuvenated PEI +Silica
Rejuvenated PEI-Silica
Re- Impregnation
*ASCOUGH, P. L., BIRD, M. I., BROCK, F., HIGHAM, T. F. G., MEREDITH, W., SNAPE, C. E. & VANE, C. H. 2009. Hydropyrolysis as a new tool for radiocarbon pre-treatment and the quantification of black carbon. Quaternary Geochronology, 4, 140-147.

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

28. moisture saturator
108mm
67mm
0.5m
1.2m
Bubbling Fluidized Bed (BFB) reactor

29. CO2 Capture with NGCC Flue Gas - test conditions

30. Effect of CO2 concentration in flue gas
12302468102625242322202625242322202625242322 15% CO2 5% CO2BreakthroughEqu.-Desorption Capacities (wt%) Equ.-Adsorption20
Cycle ID#
Flue gas: CO2, O2, H2O, balanced with N2
Potential in low CO2-containing gas mixture application

31. 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
505254565860024681012024681012simulated flue gas (NGCC) simulated flue gas (PC) by adsorption by desorption breakthrough Capacities (wt%) Cycle IDsimulated 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

32. 01020304050600.40.50.60.70.80.91.01.1 Test serial 1 Test serial 2 Normalized CO2 adsorption capacity q/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

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

34. Synthesis of new adsorbent materials - New large mesoporous PEI-silica adsorbents

35. PEI impregnated in new large mesoporous silica - synthesis
Drying
PEI Impregnation
H2O Evaporation
Vacuum Drying
MCF-17-x-y
Preparation of Adsorbents
x-batch number y-weight loading of PEI
SiO2
Synthesis large mesoporous silica
Surfactant +Silica precursor
Hydrothermal treatment
Calcination
SiO2
* P. Schmidt-Winkel, W.W. Lukens, P. Yang, B.F. Chmelka, G.D. StuckyMesocellular siliceous foams with uniformly sized cells and windows. Journal of The American Chemical Society, 121 (1999), pp. 154–155
* XU, X., SONG, C., ANDRESEN, J. M., MILLER, B. G. & SCARONI, A. W. 2002. Novel Polyethylenimine-Modified Mesoporous Molecular Sieve of MCM- 41 Type as High-Capacity Adsorbent for CO2 Capture. Energy & Fuels, 16, 1463-1469

36. CO2 uptake at 75 oC (wt.%)
5%
15%
100%
BL-40
9.1
10.4
11.7
MCF-17-1-60
14.5
17.0
18.0
MCF-17-2-60
14.5
15.7
16.0
BET Surface Area (m2/g)
Mesopore Volume (cm3/g)
Mean pore diameter (nm)
Base Line
269.4
1.4
25
MCF-17-1
500.1
2.1
25
MCF-17-2
463.5
2.1
25
•
All isotherms conducted at 77K by nitrogen.
•
Larger BET surface area, larger mass transfer boundary.
•
Higher pore volume, higher PEI loading---up to 70 wt.% theoretical loading.
•
Base line 40 wt.% PEI loading.
•
MCF-17-1 and MCF-17-2, 60 wt.% PEI loading.
PEI impregnated large mesoporous silica synthesis
0
10
20
30
40
50
60
70
0
0.2
0.4
0.6
0.8
1
Quantity Adsorbed (mmol/g)
Relative Pressure (p/po)
Mesoporous silica isotherm
Base Line
MCF-17-1
MCF-17-2
0%
2%
4%
6%
8%
10%
12%
14%
16%
0
10
20
30
40
50
60
70
CO2 uptake (wt.%)
Time (min)
MCF-17-1-60
MCF-17-2-60
BL-40

37. 0%
2%
4%
6%
8%
10%
12%
14%
16%
18%
MCF-17-2
CO2 uptake (wt.%)
5% CO2 uptake
MCF-17-2-50
MCF-17-2-60
MCF-17-2-70
150, 4%
0%
2%
4%
6%
8%
10%
12%
14%
30
50
70
90
110
130
150
CO2 uptake (wt.%)
Temperature (oC)
15% CO2 uptake
BL-40
MCF-17-1-60
MCF-17-2-60
MCF-17-2-60: 99oC, 11.20%
BL-40: 70oC, 9.90%
MCF-17-1-60: 90oC, 12.15%
•
PEI-silica under isobar condition showing that the new adsorbent materials are particularly suitable for NGCC.
•
TGA data from slow heating rate (0.2 C/min) and 15% CO2 to get pseudo-equilibrium adsorption capacities.
•
Sample started to regain CO2 after minimum point, may be due to the formation of secondary products, as suggested by [Drage et al., Microporous Mesoporous Mater. 2008, 116: 504].
•
CO2 uptake increase by increase PEI loading from 50 wt.% to 70 wt.% at 5% CO2, 75 oC condition

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

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

40. 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

41. Comparison of power losses for NGCC power plants with and without CO2 capture
fcomcapaugfecQEEEEQE−−− ==η cη ηη−=Δ
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

42. 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
raddespwrHTTCqQΔ+−=)(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) ΔHr is the heat of adsorption (kJ/kg-CO2 adsorbed)

43. PEI reductive rejuvenation by - Hypy/autoclave
Oxidised PEI-silica
Hypy/autoclave + Catalyst
Rejuvenated PEI +Silica
Rejuvenated PEI-Silica
Re- Impregnation
*ASCOUGH, P. L., BIRD, M. I., BROCK, F., HIGHAM, T. F. G., MEREDITH, W., SNAPE, C. E. & VANE, C. H. 2009. Hydropyrolysis as a new tool for radiocarbon pre-treatment and the quantification of black carbon. Quaternary Geochronology, 4, 140-147.

44. 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 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.

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