CO₂ Capture with Capsules of Ionic Liquid/Amines

Journal Article · 01 May 2024 · ACS Applied Engineering Materials

DOI: https://doi.org/10.1021/acsaenm.4c00118 · OSTI ID:2407061

Al-Mahbobi, Luma  ^[1]; Klemm, Aidan ^[2]; Taylor, Cameron ^[3]; Gurkan, Burcu  ^[2]; Pentzer, Emily  ^[3]

---

1. Texas A&M University, College Station, TX (United States); Case Western Reserve University
2. Case Western Reserve University, Cleveland, OH (United States)
3. Texas A&M University, College Station, TX (United States)

Carbon capture remains an urgent issue that has gained a great deal of attention over the past few decades. Aqueous amines have excellent selectivity, but present corrosion and volatility issues, whereas ionic liquids (ILs) have negligible volatility and tunable physical properties, but high viscosities. One approach to improve the practical performance of these liquids is encapsulating them in a CO₂ permeable polymer shell to enhance the accessibility of the liquid and the CO₂ absorption rate. In this work, we report the encapsulation of a mixture of amine and IL (i.e., monoethanolamine (MEA) and 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM][BF₄])) and demonstrate enhanced carbon capture performance. A soft-template approach and interfacial polymerization are used to give capsules with liquid core (64 wt %) and polyurea shell. Compared to the bulk liquid, the encapsulated liquid shows improved thermal stability over cycles of absorption at 25 °C, and desorption at 75 °C. The capsules with core of [BMIM][BF₄]-MEA show 0.2 mol CO₂/kg of capsules at 1 bar CO₂, compared to the bulk liquid, which has 0.05 mol CO₂/kg of sorbent. This is attributed to the limited evaporation of the amines. Alternatively, the same capsules but with 5 wt % of piperazine (Pz) in the core have doubled gravimetric CO₂ capacity of the capsules (0.4 mol CO₂/kg of capsules); performance is evaluated over 10 capture–release cycles showing minimal mass loss. Characterization of the CO₂ uptake of the polymer shell itself reveals that the shell contributes only ~10% of the observed capacity, likely attributed to amine functionalities of the polymer. Here, this facile approach to encapsulating such “active” liquids can be applied to other CO₂ selective solvents that are volatile, viscous, and corrosive.

• Research Organization: Case Western Reserve University, Cleveland, OH (United States)
• Sponsoring Organization: USDOE Office of Science (SC), Basic Energy Sciences (BES)
• Grant/Contract Number: SC0022214
• OSTI ID: 2407061
• Journal Information: ACS Applied Engineering Materials, Journal Name: ACS Applied Engineering Materials Journal Issue: 5 Vol. 2; ISSN 2771-9545
• Publisher: ACS PublicationsCopyright Statement
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
amines
carbon capture
direct air capture
emulsion
encapsulation
ionic liquid
liquids
mixtures
solvents