Direct Air Capture of CO2 with Aqueous Amino Acids and Solid Bis-iminoguanidines (BIGs)

Radu Custelcean, Neil J. Williams, Kathleen A. Garrabrant, Pierrick Agullo, Flavien M. Brethomé, Halie J. Martin, Michelle K. Kidder

Research output: Contribution to journalArticlepeer-review

63 Scopus citations

Abstract

We report a bench-scale direct air capture (DAC) process comprising CO2 absorption with aqueous amino acid salts (i.e., potassium glycinate, potassium sarcosinate), followed by room-temperature regeneration of the amino acids by reaction with solid meta-benzene-bis(iminoguanidine) (m-BBIG), resulting in crystallization of the hydrated m-BBIG carbonate salt, (m-BBIGH2)(CO3)(H2O)n (n = 3-4). The CO2 is subsequently released by mild heating (60-120 °C) of the carbonate crystals, which regenerates the m-BBIG solid quantitatively. This low-temperature crystallization-based DAC process circumvents the need to heat the aqueous amino acid sorbents, thereby minimizing their loss through thermal and oxidative degradation. The CO2 cyclic capacity for the sarcosine/m-BBIG system, measured over three consecutive absorption/regeneration cycles, is in the range of 0.12-0.20 mol/mol. The regeneration energy of m-BBIG, comprising the enthalpy of CO2 and water release, and the sensible heat, is 360 kJ/mol (8.2 GJ/ton CO2). Alternatively, the aqueous amino acids can be regenerated by boiling under reflux, with measured cyclic capacities of up to 0.64 mol/mol.

Original languageEnglish
Pages (from-to)23338-23346
Number of pages9
JournalIndustrial and Engineering Chemistry Research
Volume58
Issue number51
DOIs
StatePublished - Dec 26 2019

Funding

This research was supported by the US Department of Energy, Office of Science, Basic Energy Sciences, Chemical Sciences, Geosciences, and Biosciences Division.

FundersFunder number
US Department of Energy
Office of Science
Basic Energy Sciences
Chemical Sciences, Geosciences, and Biosciences Division

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