Subtle changes in hydrogen bond orientation result in glassification of carbon capture solvents

José Leobardo Bañuelos, Mal Soon Lee, Manh Thuong Ngyuen, Difan Zhang, Deepika Malhotra, David C. Cantu, Vassiliki Alexandra Glezakou, Roger Rousseau, Thomas F. Headen, Robert M. Dalgliesh, David J. Heldebrant, Trent R. Graham, Kee Sung Han, Steven R. Saunders

Research output: Contribution to journalArticlepeer-review

Abstract

Water-lean CO2 capture solvents show promise for more efficient and cost-effective CO2 capture, although their long-term behavior in operation has yet to be well studied. New observations of extended structure solvent behavior show that some solvent formulations transform into a glass-like phase upon aging at operating temperatures after contact with CO2. The glassification of a solvent would be detrimental to a carbon-capture process due to plugging of infrastructure, introducing a critical need to decipher the underlying principles of this phenomenon to prevent it from happening. We present the first integrated theoretical and experimental study to characterize the nano-structure of metastable and glassy states of an archetypal single-component alkanolguanidine carbon-capture solvent and assess how minute changes in atomic-level interactions convert the solvent between metastable and glass-like states. Small-angle neutron scattering and neutron diffraction coupled with small- and wide-angle X-ray scattering analysis demonstrate that minute structural changes in solution precipitae reversible aggregation of zwitterionic alkylcarbonate clusters in solution. Our findings indicate that our test system, an alkanolguanidine, exhibits a first-order phase transition, similar to a glass transition, at approximately 40 °C - close to the operating absorption temperature for post-combustion CO2 capture processes. We anticipate that these phenomena are not specific to this system, but are present in other classes of colvents as well. We discuss how molecular-level interactions can have vast implications for solvent-based carbon-capture technologies, concluding that fortunately in this case, glassification of water-lean solvents can be avoided as long as the solvent is run above its glass transition temperature.

Original languageEnglish
Pages (from-to)19009-19021
Number of pages13
JournalPhysical Chemistry Chemical Physics
Volume22
Issue number34
DOIs
Publication statusPublished - Sep 14 2020

ASJC Scopus subject areas

  • Physics and Astronomy(all)
  • Physical and Theoretical Chemistry

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