Sub-Ambient Temperature Direct Air Capture of CO ₂ using Amine-Impregnated MIL-101(Cr) Enables Ambient Temperature CO ₂ Recovery

Journal Article · Wed Feb 09 00:00:00 EST 2022 · JACS Au

DOI:https://doi.org/10.1021/jacsau.1c00414· OSTI ID:1844271

Rim, Guanhe ^[1]; Kong, Fanhe ^[1]; Song, Mingyu ^[1]; Rosu, Cornelia  ^[1]; Priyadarshini, Pranjali  ^[1]; Lively, Ryan P.  ^[1]; Jones, Christopher W.  ^[1]

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1. School of Chemical & Biomolecular Engineering, Georgia Institute of Technology, 311 Ferst Drive, Atlanta, Georgia 30332-0100, United States

Due to the dramatically increased atmospheric CO₂ concentration and consequential climate change, significant effort has been made to develop sorbents to directly capture CO₂ from ambient air (direct air capture, DAC) to achieve negative CO₂ emissions in the immediate future. However, most developed sorbents have been studied under a limited array of temperature (>20 °C) and humidity conditions. In particular, the dearth of experimental data on DAC at sub-ambient conditions (e.g., –30 to 20 °C) and under humid conditions will severely hinder the largescale implementation of DAC because the world has annual average temperatures ranging from –30 to 30 °C depending on the location and essentially no place has a zero absolute humidity. To this end, we suggest that understanding CO₂ adsorption from ambient air at sub-ambient temperatures, below 20 °C, is crucial because colder temperatures represent important practical operating conditions and because such temperatures may provide conditions where new sorbent materials or enhanced process performance might be achieved. Here we demonstrate that MIL- 101(Cr) materials impregnated with amines (TEPA, tetraethylenepentamine, or PEI, poly(ethylenimine)) offer promising adsorption and desorption behavior under DAC conditions in both the presence and absence of humidity under a wide range of temperatures (–20 to 25 °C). Depending on the amine loading and adsorption temperature, the sorbents show different CO₂ capture behavior. With 30 and 50 wt % amine loadings, the sorbents show weak and strong chemisorption-dominant CO₂ capture behavior, respectively. Interestingly, at –20 °C, the CO₂ adsorption capacity of 30 wt % TEPA-impregnated MIL-101(Cr) significantly increased up to 1.12 mmol/g from 0.39 mmol/g at ambient conditions (25 °C) due to the enhanced weak chemisorption. More importantly, the sorbents also show promising working capacities (0.72 mmol/g) over 15 small temperature swing cycles with an ultralow regeneration temperature (–20 °C sorption to 25 °C desorption). The sub-ambient DAC performance of the sorbents is further enhanced under humid conditions, showing promising and stable CO₂ working capacities over multiple humid small temperature swing cycles. These results demonstrate that appropriately designed DAC sorbents can operate in a weak chemisorption modality at low temperatures even in the presence of humidity. Significant energy savings may be realized via the utilization of small temperature swings enabled by this weak chemisorption behavior. This work suggests that significant work on DAC materials that operate at low, sub-ambient temperatures is warranted for possible deployment in temperate and polar climates.

• Research Organization: Georgia Institute of Technology, Atlanta, GA (United States)
• Sponsoring Organization: USDOE Office of Fossil Energy and Carbon Management (FECM); USDOE Office of Fossil Energy (FE)
• Grant/Contract Number: FE-FE0031952; FE0031952
• OSTI ID: 1844271
• Alternate ID(s): OSTI ID: 1846736
• Journal Information: JACS Au, Journal Name: JACS Au Vol. 2 Journal Issue: 2; ISSN 2691-3704
• Publisher: American Chemical Society
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
metal−organic framework
amine
direct air capture
sub-ambient conditions
temperature swing adsorption