Carbon dioxide adsorption using amine-functionalized mesocellular siliceous foams

Abstract

Mesocellular siliceous foams (MCFs) with and without remaining template were prepared and modified by polyethylenimine (PEI) or mixed amines [Diethylenetriamine and PEI or 3-aminopropyltrimethoxysilane (APTMS) and PEI]. These samples were evaluated for their adsorption capacities for CO 2 at different temperatures. With the increase of PEI loading, the optimal adsorption temperature shifts to higher temperature for samples prepared in our study. The remaining template in MCF materials plays an important role in promoting CO 2 adsorption capacity, which could be 3.24 mmol/g when the amount of PEI loading is 70 % at 85°C. Meanwhile, the remaining template contributes greatly to the dispersion of PEI, resulting in higher adsorption capacity at low temperature. The effect of the amount of remaining template was studied, and it was found that CO 2 adsorption capacity decreases with increasing template. The CO 2 adsorption capacities for mixed-amine-modified MCFs are higher than those of the samples modified by PEI only, which was ascribed to the better dispersion of PEI. MCF modified with the mixing of APTMS and PEI exhibited highest adsorption capacity of 2.67 mmol/g at 50°C. These findings reveal that pore structure, PEI loading, PEI dispersion, and remaining template work together to influence the CO 2 adsorption performance.

Unveiling the Desorption Performance and Thermal Stability of Unmodified Polyamine-Containing CO2 Adsorbents

“…The results obtained for 30 and 40 wt % loadings are consistent with the data reported by Heydari-Gorji et al The sorbent with 50 wt % loading cannot be compared with their observations because they did not present a sorbent with completely filled pores. The study of Ma et al has such a sorbent (i.e., MCF­(c)/PEI-70); however, their findings show a higher effect of temperature on the sorbent’s capacity, likely due to a longer exposure time to CO 2 .…”

“…Zhao et al studied the thermal stability of TEPA at 140 °C using a fluidized bed and found that entrained amine vapor can effectively impede TEPA’s diffusion from the porous medium, which may also occur in overloaded sorbents with a polymer layer coating the external surface. Nevertheless, increasing polymer loading requires higher adsorption temperatures to facilitate CO 2 diffusion, , which also applies to the reverse step . Indeed, sorbents with high polymer loading can offer high adsorption capacity; however, this comes at the cost of requiring high desorption temperatures and times, which can significantly affect the sorbent’s stability.…”

“…As aforementioned, previous studies have primarily focused on improving the adsorption efficiency of amine solid sorbents through various means, such as screening different polymers, modifying polymer structure, ,, and using high polymer loadings and elevated temperatures. ,, However, little attention has been given to identifying the practical desorption temperature (PDT) that considers the structural properties of the polymers and maintains their integrity. PDT is the temperature that enables fast desorption kinetics while preserving the thermal stability of the sorbent.…”

Recent advances in direct air capture by adsorption

“…Several studies have explored the role of additives in carbon capture, and most of them were performed under post-combustion conditions. 364–369 Accordingly, the main types of effective additives are surfactants (poly(ethylene glycol) (PEG), 300,370–373 glycerol, cetyltrimethylammonium bromide (CTAB), cetyltrimethylammonium chloride (CTAC), Pluronic P123, and sorbitan monooleate (Span80), silanes, 374,375 sulfur-containing compounds, antioxidants, 376 ionic liquids, 377 and potassium carbonate. 378 PEG has been investigated most frequently and showed positive effects on adsorption properties, possibly because of its rich hydroxyl groups that can facilitate better amine dispersion and attract more water molecules.…”

Improved epoxy thermosets by the use of poly(ethyleneimine) derivatives

“…By modification of PEI, the application range can be further expanded. Amidation with acids, alkoxylation, alkylation and carboxylation has been performed, leading to PEI-modified structures used as CO 2 cells [123,124], detectors with specific recognition elements [125,126], drug delivery [127] or nano-carriers [128], among others.…”