Direct evidence of CO2 softening effects on coal using nanoindentation. (1st September 2022)
- Record Type:
- Journal Article
- Title:
- Direct evidence of CO2 softening effects on coal using nanoindentation. (1st September 2022)
- Main Title:
- Direct evidence of CO2 softening effects on coal using nanoindentation
- Authors:
- Zhang, Guanglei
Ranjith, P.G.
Lyu, Qiao - Abstract:
- Abstract: Sequestration of carbon dioxide (CO2 ) in deep coal seams has been identified as a promising technique to mitigate global warming with added benefit of enhancing coalbed methane recovery. Understanding coal structure and its reactivity with injected CO2 is important for CO2 sequestration in coal. Despite the long-standing hypothesis, there is no direct evidence of softening effects of CO2 on coal due to CO2 -coal interactions. Here, we used optical microscopy and nanoindentation to study changes in microstructures and nanoscale mechanical properties of untreated and CO2 -treated anthracite coal. Microscopic images indicated coal surface cracked after short-term treatment and then became highly wrinkled and distorted after long-term treatment. These changes reflect that CO2 dissolves in the macromolecular network and acts as a solvent allowing a rearrangement of the network. Nanoindentation directly confirmed the softening effects of CO2 on nanoscale mechanical properties, including Young's modulus, hardness, and fracture toughness. Interestingly, all these changes were reversible to some extent after removing CO2 from coal. These findings provide new evidence for clarifying the polymeric macromolecular structure of coal and directly demonstrated the softening effects of CO2 on the macromolecular structure. Highlights: Softening effects of CO2 on coal is first confirmed in nanoscale. Coal surface becomes cracked and highly distorted after interacting with CO2 .Abstract: Sequestration of carbon dioxide (CO2 ) in deep coal seams has been identified as a promising technique to mitigate global warming with added benefit of enhancing coalbed methane recovery. Understanding coal structure and its reactivity with injected CO2 is important for CO2 sequestration in coal. Despite the long-standing hypothesis, there is no direct evidence of softening effects of CO2 on coal due to CO2 -coal interactions. Here, we used optical microscopy and nanoindentation to study changes in microstructures and nanoscale mechanical properties of untreated and CO2 -treated anthracite coal. Microscopic images indicated coal surface cracked after short-term treatment and then became highly wrinkled and distorted after long-term treatment. These changes reflect that CO2 dissolves in the macromolecular network and acts as a solvent allowing a rearrangement of the network. Nanoindentation directly confirmed the softening effects of CO2 on nanoscale mechanical properties, including Young's modulus, hardness, and fracture toughness. Interestingly, all these changes were reversible to some extent after removing CO2 from coal. These findings provide new evidence for clarifying the polymeric macromolecular structure of coal and directly demonstrated the softening effects of CO2 on the macromolecular structure. Highlights: Softening effects of CO2 on coal is first confirmed in nanoscale. Coal surface becomes cracked and highly distorted after interacting with CO2 . Changes in structural and mechanical properties are reversible to some extent after CO2 removal. … (more)
- Is Part Of:
- Energy. Volume 254:Part A(2022)
- Journal:
- Energy
- Issue:
- Volume 254:Part A(2022)
- Issue Display:
- Volume 254, Issue 1 (2022)
- Year:
- 2022
- Volume:
- 254
- Issue:
- 1
- Issue Sort Value:
- 2022-0254-0001-0000
- Page Start:
- Page End:
- Publication Date:
- 2022-09-01
- Subjects:
- CO2 sequestration -- Coal softening -- Nanoindentation -- Macromolecular structure
Power resources -- Periodicals
Power (Mechanics) -- Periodicals
Energy consumption -- Periodicals
333.7905 - Journal URLs:
- http://www.elsevier.com/journals ↗
- DOI:
- 10.1016/j.energy.2022.124221 ↗
- Languages:
- English
- ISSNs:
- 0360-5442
- Deposit Type:
- Legaldeposit
- View Content:
- Available online (eLD content is only available in our Reading Rooms) ↗
- Physical Locations:
- British Library DSC - 3747.445000
British Library DSC - BLDSS-3PM
British Library HMNTS - ELD Digital store - Ingest File:
- 22304.xml