Carbon formation during conversion of CO 2 to synthetic fuels by means of electrolysis

Transcription

1 Carbon formation during conversion of CO 2 to synthetic fuels by means of electrolysis Closing the Carbon Cycle: Fuels from Air, Phoenix, 29/ Theis L. Skafte (1,2), P. Blennow (1), J. Hjelm (2), and C. Graves (2) (1) Haldor Topsoe A/S, Haldor Topsøes Allé 1, 2800 Kgs. Lyngby, Denmark 1(2) Department of Energy Conversion and Storage, Technical University of Denmark, Risø campus, Frederiksborgvej 399, 4000 Roskilde, Denmark

2 Outline Haldor Topsoe in brief Introduction - SOEC, potential usage - Demonstrations - Motivation - The method briefly Carbon during electrolysis - Cell-level - Stack-level The carbon threshold The carbon threshold 3 scenarios Conclusions 2

3 Haldor Topsoe In brief Established in 1940 by Dr. Haldor Topsøe. Private 100% family-owned company. Market leader in heterogeneous catalysis and surface science for more than 75 years. Ammonia Methanol HyCO (syngas) 2,600 employees in 10 countries. Headquarters in Copenhagen, Denmark. Production in Frederikssund, Denmark, Houston, USA, and Tianjin, China. Spends around 10% of revenue on R&D revenue DKK 5,785m (~USD 850m) 2015 operating profit DKK 502m (~USD 75m) 3

4 Introduction Solid oxide electrolysis - potential usage Water electrolysis 2 H 2 O 2 H 2 + O 2 CO 2 electrolysis 2 CO 2 2 CO + O 2 Co-electrolysis CO 2 + H 2 O H 2 + CO + O 2 H 2 can be used directly or indirectly for e.g. biogas upgrading CO 2 from flue gas stream or air Can be used for CO and O 2 production Syngas (H 2 + CO) can be converted into CO 2 -neutral transportation fuel (CH 4, diesel, etc.) 4 Graves et al., Solid State Ionics, (2011)

5 Introduction Demonstrations Synergy between SOC technology and catalysis competencies Gas more interesting than electrons Demonstration of technology Stepping stones until market is ready EUDP project: Electrolysis Upgraded Biogas a 50 kw SOEC system 5

6 Introduction Motivation market pull vs. society pull Price of CO 2 emission vs. value of CO 2 utilization There has to be a business! + = Low cost raw materials lifetime efficiency Lifetime = Degradation mechanisms + failure mechanisms High efficiency High CO fraction Carbon formation on Ni 6 Offgridworld.com Rostrup-nielsen, J. R..,Catalysis Today, 272, (2016)

7 Introduction Carbon during electrolysis 2 CO 2 2 CO + O 2 2 CO CO 2 + C (Boudouard reaction) 7 a) In the safe window b) Optimize efficiency c) Outside safe window

8 The carbon threshold The method briefly YSZ electrolyte Ni/YSZ electrode 8 Skafte et al., ECS Trans., 68 (2015)

9 The carbon threshold Cell-level Current Porosity 9

10 The carbon threshold Stack-level Gradients, cell 10 Gradients, stack Steel components

11 Scenario a) - Safe Cell-level Stack-level 11

12 Scenario b) - Accidents YSZ electrolyte Ni/YSZ electrode YSZ electrolyte Ni/YSZ electrode 12

13 Scenario b) - Accidents YSZ electrolyte Ni/YSZ electrode CO CO 2 13 Irvine, J. T. S et al., Nature Energy, 1(1), (2016) Skafte et al., in preparation

14 Scenario c) - Unsafe 14

15 Scenario c) - Unsafe YSZ electrolyte CO CO 2 15 Irvine, J. T. S et al., Nature Energy, 1(1), (2016)

16 Scenario c) - Unsafe Sulfur passivation J.R. Rostrup-Nielsen CO CO 2 6 ppb for 1 min 100 ppb for 50+ h 16 J. R. Rostrup-Nielsen, J. Catal., 85 (1984) Irvine, J. T. S et al., Nature Energy, 1(1), (2016)

17 Scenario c) - Unsafe 750, pco 0.9 Ni cell Non-Ni cell Get rid of Ni! 17 Skafte et al., ECS Trans., 72(7), (2016) Graves et al., ECS Trans., 72(7), (2016)

18 Conclusions 1) CO2 reduction in SOEC works and the technology is ready! It is now a matter of reducing costs.. 2) Carbon deposition and sulfur poisoning are more problematic issues than expected in full cells and stacks. 3) To optimize efficiency further, Ni-free catalyst is needed! 18

19 19 Thank you for your attention!

20 Backup slides References: [1] Graves, C., Ebbesen, S. D., & Mogensen, M., Co-electrolysis of CO2 and H2O in solid oxide cells: Performance and durability, Solid State Ionics, 192(1), , (2011). [2] Rostrup-nielsen, J. R., 50 years in catalysis, Lessons learned, Catalysis Today, 272, 2 5, (2016). [3] Skafte, T. L., Graves, C., Blennow, P., & Hjelm, J., Carbon Deposition during CO2 Electrolysis in Ni-Based Solid-Oxide-Cell Electrodes, ECS Transactions, 68, , (2015). [4] Irvine, J. T. S., Neagu, D., Verbraeken, M. C., Chatzichristodoulou, C., Graves, C., & Mogensen, M. B., Evolution of the electrochemical interface in high-temperature fuel cells and electrolysers, Nature Energy, 1(1), (2016). [5] J. R. Rostrup-Nielsen, Sulfur-passivated nickel catalysts for carbon-free steam reforming of methane, J. Catal., 85, 31 43, (1984). [5] Skafte, T. L., Sudireddy, B. R., Blennow, P., & Graves, C., Carbon and Redox Tolerant Infiltrated Oxide Fuel-Electrodes for Solid Oxide C6lls, ECS Transactions, 72(7), , (2016). [7] Graves, C., Martinez, L., & Sudireddy, B. R., High Performance Nano-Ceria Electrodes for Solid Oxide Cells, ECS Transactions, 72(7), (2016). 20

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22 Topsoe Stack Platform (TSP-1) 75 cells combined with interconnects, spacers and sealings in one stack Internal fuel manifold External air manifold Cell group voltage prob Compression free han Robustness and leak ti QA test in SOFC mode 22