Microwave Regeneration and Thermal and Oxidative Stability of Imidazolium Cyanopyrrolide Ionic Liquid for Direct Air Capture of Carbon Dioxide

Abstract

Understanding the oxidative and thermal degradation of CO 2 sorbents is essential for assessing long-term sorbent stability in direct air capture (DAC). The potential degradation pathway of imidazolium cyanopyrrolide, an ionic liquid (IL) functionalized for superior CO 2 capacity and selectivity, is evaluated under accelerated degradation conditions to elucidate the secondary reactions that can occur during repetitive absorption-desorption thermal-swing cycles. The combined analysis from various spectroscopic, chromatographic, and thermal gravimetric meas-urements indicated that radical and S N 2 mechanisms in degradation are encouraged by the nucleophilicity of the anion. Thickening of the liquid and gas evolution are accompanied by 50 % reduction in CO 2 capacity after a 7-day exposure to O 2 under 80 °C. To prevent long exposure to conventional thermal heating, microwave (MW) regeneration of the CO 2 -reactive IL is used, where dielectric heating at 80 and 100 °C rapidly desorbs CO 2 and regenerates the IL without any measurable degradation.

Polymer Sorbent Design for the Direct Air Capture of CO2

“…Additionally, methods that deviate from conventional temperature or pressure swing desorption can potentially make the regeneration process more energy efficient. Previous works have studied the use of microwave radiation, , ultrasound, magnetic particle, photoswitching, and electric swings to assist in reducing energy penalties for regenerating DAC sorbents and suggest excellent opportunities for future technologies . Similarly, the integration of DAC technologies with processes to convert CO 2 into useful products is important to increasing the economic viability of these systems, potentially eliminating large needs of carbon storage and transport.…”

Tuning Surface, Phase, and Magnetization of Superparamagnetic Magnetite by Ionic Liquids: Single-Step Microwave-Assisted Synthesis

“…1-Hexyl-3-methyl-imidazolium chloride ([HMIM]­[Cl], 98%), 1-ethyl-3-methyl-imidazolium bis­(trifluoromethylsulfonyl)­imide ([EMIM]­[TFSI], 99%), and 1-hexyl-3-methyl-imidazolium bis­(trifluoromethylsulfonyl)­imide ([HMIM]­[TFSI], 99%) were purchased from IoLiTec. [EMIM]­[2-CNpyr] was synthesized in-house via the previously published procedure . Pyrrole 2-carbonitrile (99%), 1-methyl imidazole (98%), bromo ethane (99%), diethyl ether (>99%, anhydrous), methanol (99.8%, HPLC grade), and ethyl acetate (99.9%) were purchased from Sigma-Alrich.…”

“…[EMIM][2-CNpyr] was synthesized in-house via the previously published procedure. 35 Pyrrole 2-carbonitrile (99%), 1-methyl imidazole (98%), bromo ethane (99%), diethyl ether (>99%, anhydrous), methanol (99.8%, HPLC grade), and ethyl acetate (99.9%) were purchased from Sigma-Alrich. Ferrous chloride tetrahydrate (FeCl 2 •4H 2 O), ferric chloride hexahydrate (FeCl 3 • 6H 2 O), and deionized (DI) water were purchased from Thermo Scientific.…”

CO2 Capture with Capsules of Ionic Liquid/Amines

“…25−28 Such task-specific ionic liquids (TSILs) have demonstrated promising potential in DAC. 29,30 However, ILs suffer from high viscosity that impedes fast absorption rates of CO 2 and TSILs exhibit increase in viscosity upon CO 2 binding, limiting mass transport of CO 2 . 31 To overcome challenges associated with the viscosity and cost of TSILs, small molecule amines have been introduced to ILs for improved CO 2 absorption, providing both chemisorption pathways and low-volatility solvents for amines.…”