Oxidation‐Resistant, Cost‐Effective Epoxide‐Modified Polyamine Adsorbents for CO₂ Capture from Various Sources Including Air

Abstract

CO2 adsorbents based on the reaction of pentaethylenehexamine (PEHA) or tetraethylenepentamine (TEPA) with propylene oxide (PO) were easily prepared in “one pot” by impregnation on a silica support in water. The starting materials were readily available and inexpensive, facilitating the production of the adsorbents on a large scale. The prepared polyamine/epoxide adsorbents were efficient in capturing CO2 and could be regenerated under mild conditions (50–85 °C). They displayed a much‐improved stability compared with their unmodified amine counterparts, especially under oxidative conditions. Leaching of the active organic amine became minimal or nonexistent after treatment with the epoxide. The adsorption as well as desorption kinetics were also greatly improved. The polyamine/epoxide adsorbents were able to capture CO2 from various sources including ambient air and indoor air with CO2 concentrations of only 400–1000 ppm. The presence of water, far from being detrimental, increased the adsorption capacity. Their use for indoor air quality purposes was explored.

Drastic enhancement of carbon dioxide adsorption in fluoroalkyl-modified poly(allylamine)

“…The fluoroalkyl groups in F-PAA-C60 triple the DAC capacity of PAA-C60 at low temperature, in line with the fourfold increase of CO2 uptake observed in a pure CO2 stream. With a DAC capacity of 1.30 mmol g -1 (2.28 mmol CO2 per gram of PAA) at 30 °C, F-PAA-C60 compares well with other materials reported in the literature such as PEI loaded SBA-15 (1.10 mmol g -1 ), [27] PEHA or TEPA co-impregnated with PO on silica support (1.25 and 1.34 mmol g -1 , respectively), [23] and amine-based nanofibrillated cellulose (1.39 mmol g -1 ). [28] A comprehensive table with key features and performance of polyamine-based DAC sorbent materials is provided in the SI, Table S2.…”

“…Additives can also increase thermal stability of the sorbent, for example propylene oxide (PO) was added to pentaethylenehexamine (PEHA) and tetraethylenepentamine (TEPA) before impregnation onto silica support significantly improving the oxidative stability of the sorbent. [23] The direct air capture performance of these sorbents was tested at 25 °C, under 400 ppm CO2, and the uptakes were 1.25 and 1.34 mmol CO2 g -1 for the PEHA and TEPA based adsorbents, respectively. Driven by the above findings on the pivotal role of polymer conformation in the CO2 capture process, and the beneficial effect of hydrophobic features on amine accessibility, we present here the successful implementation of a strategy to improve the CO2 capture performance at ambient temperature of highly loaded poly(allylamine) (PAA) fullerene cross-linked sorbents.…”

Sorbents for the Direct Capture of CO2 from Ambient Air

“…Amine-modified sorbents can be categorized into three classes based on their preparation methods,examples of each are shown in Figure 4. [142] Class 1sorbents can be prepared by physically impregnating amines into porous materials, [87,[143][144][145][146][147][148][149][150][151][152][153][154][155][156][157][158][159] but amines with low molecular weights easily leach during sorption and regeneration processes. [146,160] Class 2s orbents are prepared by chemically grafting the amine functional group onto the support surface,t hereby stabilizing the sorbent during regeneration.…”

The application of amine-based materials for carbon capture and utilisation: an overarching view

“…68 However, since the heat of adsorption represents the energy required to remove CO 2 to re-generate the adsorbent, 69 the lower heat of adsorption of secondary and tertiary amines would be advantageous in reducing regeneration energy. 58,70,71 More recent work by the Jones group, in which heats of adsorption were measured directly by calorimetry, found that the heats of adsorption of strongly basic primary and secondary amines were approximately equal, at around 90 kJ mol À1 . 72 Considering the CO 2 uptakes and heats of adsorption for a range of aminosilanes of varying steric constraints, the authors postulated that the higher CO 2 adsorption observed for primary amines under dilute conditions is more likely to be dependent on entropic rather than enthalpic factors.…”