Amine‐Tethered Solid Adsorbents Coupling High Adsorption Capacity and Regenerability for CO₂ Capture From Ambient Air

Abstract

Silica supported poly(ethyleneimine) (PEI) materials are prepared via impregnation and demonstrated to be promising adsorbents for CO(2) capture from ultra-dilute gas streams such as ambient air. A prototypical class 1 adsorbent, containing 45 wt% PEI (PEI/silica), and two new modified PEI-based aminosilica adsorbents, derived from PEI modified with 3-aminopropyltrimethoxysilane (A-PEI/silica) or tetraethyl orthotitanate (T-PEI/silica), are prepared and characterized by using thermogravimetric analysis and FTIR spectroscopy. The modifiers are shown to enhance the thermal stability of the polymer-oxide composites, leading to higher PEI decomposition temperatures. The modified adsorbents present extremely high CO(2) adsorption capacities under conditions simulating ambient air (400 ppm CO(2) in inert gas), exceeding 2 mol(CO (2)) kg(sorbent)(-1), as well as enhanced adsorption kinetics compared to conventional class 1 sorbents. The new adsorbents show excellent stability in cyclic adsorption-desorption operations, even under dry conditions in which aminosilica adsorbents are known to lose capacity due to urea formation. Thus, the adsorbents of this type can be considered promising materials for the direct capture of CO(2) from ultra-dilute gas streams such as ambient air.

Dynamic capture of low-concentration CO2 on amine hybrid silsesquioxane aerogel

“…The CO 2 desorption capacity does not show much change under given conditions (2.68-2.85 mmol/g), especially in the range of 80-110 °C (2.83-2.85 mmol/g). It shows that spent AHSA could be well regenerated at a temperature above 80 °C within a short time of 5.5 min, while adsorbed CO 2 with other adsorbents is generally desorbed around 100-140 °C with a longer time [33,34,65,[68][69][70][71]77]. However, the CO 2 desorption time, especially total time, of AHSA is strongly affected by temperature.…”

“…8 However, AHSA should have a lower adsorption half time and higher adsorption rate after comparing the breakthrough curves of the adsorbents and AHSA. Therefore, the adsorption half time of AHSA is much lower than those of other reported adsorbents in 1% or 10% CO 2 [30,[65][66][67][68][69][70][71][72], demonstrating that it is more dynamic for low-concentration CO 2 capture.…”

Development of monolithic adsorbent via polymeric sol–gel process for low-concentration CO2 capture

“…The CO 2 desorption capacities are very close to adsorption capacities, the tiny difference results from the CO 2 desorption during purge process. It reveals that the adsorbed CO 2 in AH-RFSA could be desorbed at a only 80°C within less than 5.5 or 7.0 min without or with water, while adsorbed CO 2 with other amine based adsorbents is generally desorbed around 100-140°C with a longer time [18,35,36,[78][79][80][81][89][90][91], indicating that AH-RFSA is more dynamic and energy-saving.…”

Application of polyethylenimine‐impregnated solid adsorbents for direct capture of low‐concentration CO2

“…52 Futhermore, hyperbranched aminosilicas prepared by in situ aziridine polymerization on porous solids have been reported as adsorbents for CO 2 capture from the air. 53,54 Although some valuable progress has been made in CO 2 capture from the ambient air recently, most of the discussion has been based on advancing the support or the amine rather than on a systematic investigation of the process based on kinetic and thermodynamic CO 2 adsorption/ desorption process. Moreover, for the design of DAC systems featuring such solid amine adsorbents, detail understanding of the multiple-component adsorption containing N 2 , O 2 , CO 2 , and H 2 O is crucial because of the humid and O 2 -containing air.…”