Oxidative Stability of Amino Polymer–Alumina Hybrid Adsorbents for Carbon Dioxide Capture

Abstract

Amine/oxide hybrid carbon dioxide adsorbents prepared via impregnation of low molecular weight polymeric amines into porous oxide supports are among the most promising solid adsorbents developed for postcombustion CO 2 capture or CO 2 extraction from ambient air. The oxidative stability of adsorbents prepared by impregnation of poly(ethylenimine) (PEI) or poly(allylamine) (PAA) into mesoporous γ-alumina under humid oxidation conditions is evaluated in this work. The PEIbased adsorbents, which contain primary, secondary, and tertiary amines, are shown to degrade drastically at elevated temperatures (110 °C) and in high oxygen concentrations (21%, akin to air), with these effects reduced by both reductions in temperature (70 °C) and oxygen concentration (5%, akin to flue gas). The oxidation behavior of PEI-based adsorbents supported on alumina is qualitatively similar to past work on silica-supported PEI adsorbents. In contrast, the alumina-supported PAA adsorbents that contain only primary amines show significantly improved oxidative stability, losing only 10% or less of their original CO 2 capacity after prolonged oxidative treatment under a variety of conditions. Analysis of the fresh and thermally treated samples by Fourier transform (FT) IR, FT-Raman, and 13 C NMR spectroscopies demonstrates the clear formation of carbonyl functionalities over the oxidized PEI-based adsorbents, whereas no significant changes in the spectra for PAA samples are observed after oxidative treatments. The collected data demonstrate that secondary-amine-free, primary-amine-rich polymers such as PAA may be used to formulate supported amine adsorbents with improved oxidative stability compared to adsorbents based on PEI, which is used ubiquitously in the field today.

Shaping amine-based solid CO2 adsorbents: Effects of pelletization pressure on the physical and chemical properties

“…The data presented in Table 1 indicate that upon functionalizing the γ-alumina and silica supports, the BET surface areas and total pore volumes decreased, indicating the successful loading of organic amines into the pore space. It should be noted that the powder samples exhibit physisorption characteristics consistent with the similar samples reported in the literature [14,21,30]. One other thing to note here is that all class 1 and class 2 materials have about the same amine loadings, a widely different change in pore volume and BET surface area for class 1 versus class 2 materials could be observed.…”

Comparative Study of Molecular Basket Sorbents Consisting of Polyallylamine and Polyethylenimine Functionalized SBA‐15 for CO2 Capture from Flue Gas

“…[57] It is clear evidences howingt hat the oxidative degradation of PEI-I(50)/SBA-15 occurredd uring the heat treatment process.I nc ontrast, over the PAA(50)/SBA-15 sorbent after 260 ho fh eat treatment, although the same new IR band at 1659 cm À1 was also observed, the intensity was much lower compared with the PEI-I(50)/SBA-15 sample after 260 ho fh eat treatment (Figure 10 B). [45,[66][67][68][69][70][71] The oxidative degradation of the amine polymer was also supported by the color change in the sorbenta fter 260 ho fh eat treatment.…”

“…However,t he CO 2 sorption rate over the PAA(50)/SBA-15 sorbent was much slower. [43][44][45] Jones and his co-workerss tudied the CO 2 sorption performance of low molecular weight PAAo ver mesocellular silica foam (MCF) support for CO 2 sorption from simulated air at room temperature and found that the CO 2 adsorption capacity of PAA/MCFa dsorbents was comparable to the PEI-impregnated adsorbents at similar amine loadings. [27,28] Recently,h igh capacities were reported over the sorbents with high amine loading developed through the first approach with in situ polymerization, [35,36] the synthesis procedure is, however,v ery complicated.…”

“…[27,28] Recently,h igh capacities were reported over the sorbents with high amine loading developed through the first approach with in situ polymerization, [35,36] the synthesis procedure is, however,v ery complicated. [45] In this work, am ore systematic investigation on CO 2 capture from flue gas over the PAA-impregnatedm olecular basket sorbents has been conducted, especially in comparison to the PEI-based MBS. [29][30][31][32][33][34] Among the amine compounds investigated for the third approach,i ncluding polyethylenimine (PEI), tetraethylenepentamine (TEPA), diethanolamine( DEA),a nd dendrimers, [37][38][39][40] PEI is the most popularo ne, likely owing to its richness of amino groups in amore condensed form, relatively high nitrogen percentagei nt he molecule, and suitable molecular weightf or thermals tability.…”

Role of Alumina Basicity in CO2 Uptake in 3‐Aminopropylsilyl‐Grafted Alumina Adsorbents

“…[42] In contrast, more isolated amines are more likely to form carbamic acid (SchemeS1),w hichi saless stable species with al ower heat of adsorption (ca. [52] Alumina supports typically show more resilience to stream treatments than silica, potentially making them ap referable support for practical use. [42] These species, and other CO 2 -bound species are typically identified through bands in the 1300-1700 cm À1 region of the IR spectra (Table S1).…”