Understanding Material Compatibility in CO2Capture Systems Using Molten Alkali Metal Borates

Cameron Halliday, Nil Ozbek, T. Alan Hatton*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

12 Citations (Scopus)

Abstract

Molten alkali metal borates have been proposed as energy-efficient sorbents for the low-cost capture of CO2 at high temperatures. The molten sorbents could help to mitigate global warming by capturing CO2 from industrial sources and preventing the release of CO2 into the atmosphere. However, these novel materials operate under harsh conditions, introducing challenges of which material compatibility is one of the most important. Other than platinum, where a less than 0.1% change in performance was observed over 1000 h of continuous use, few materials were found to be compatible with the molten salts. Common ceramics, steels, and superalloys were eliminated from consideration due to corrosive oxidation of the substrate and contamination of the melt resulting in chemical degradation and reduction in the sorbent's working capacity. A high-purity nickel alloy, Nickel 200/201, with a protective oxide layer was found to perform optimally with regards to both corrosive degradation and chemical degradation. Modest corrosion rates on the order of 0.3-0.5 mm/year were estimated, and the sorbent capacity was found to drop by between a manageable 0.5 and 20% over 100 h. Various protective measures are proposed, and future work suggested, to ensure that material compatibility does not limit the potential of molten alkali metal borates to reduce CO2 emissions and contribute to a clean energy future.

Original languageEnglish
Pages (from-to)51468-51477
Number of pages10
JournalACS applied materials & interfaces
Volume12
Issue number46
DOIs
Publication statusPublished - 18 Nov 2020
Externally publishedYes

Bibliographical note

Publisher Copyright:
© 2020 American Chemical Society.

Funding

We would like to thank the MIT Energy Initiative (MITei) Seed Fund Grant Program for funding, Prof. Takuya Harada for his contributions to this project, and Kai-Jher Tan and Timothy Cavanaugh for their assistance with SEM imaging. Nil Ozbek greatly appreciates the support by The Scientific and Technological Research Council of Turkey (TÜBITAK), 2219 International Postdoctoral Research Scholarship Program.

FundersFunder number
Türkiye Bilimsel ve Teknolojik Araştirma Kurumu

    Keywords

    • carbon capture
    • corrosion
    • cyclability
    • high temperature
    • molten salts
    • stability

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