Insights into the Critical Role of Abundant-Porosity Supports in Polyethylenimine Functionalization as Efficient and Stable CO₂ Adsorbents

Abstract

The emerging polyethylenimine (PEI)-functionalized solid adsorbents have witnessed significant development in the implementation of CO2 capture and separation because of their decent adsorption capacity, recyclability, and scalability. As an indispensable substrate, the importance of selecting porous solid supports in PEI functionalization for CO2 adsorption was commonly overlooked in many previous investigations, which instead emphasized screening amine types or developing complex porous materials. To this end, we scrutinized the critical role of different commercial porous supports (silica, alumina, activated carbon, and polymeric resins) in PEI impregnation in this study, taking into account multiple perspectives. Hereinto, the present results identified that abundant larger pore structures and surface functional groups were conducive to loading a considerable amount of PEI molecules. Various supports after PEI functionalization had great differences in adsorption capacities, amine efficiencies, and the corresponding optimal temperatures. In addition, more attention was paid to the role of porous supports in long-term stability during the consecutive adsorption–regeneration cycles, while N2 and CO2 purging as regeneration strategies, respectively. Especially, CO2-induced degradation due to urea species formation was specifically recognized in a SiO2-based adsorbent, which would induce serious concerns in CO2 cyclic capture. On the other side, we also confirmed that adopting conventional porous supports, for example, HP20, could achieve superior adsorption performance (above 4 mmol CO2/g) and cyclic stability (around 1% loss after 30 cycles) rather than the ones synthesized through complex approaches, which ensured the availability and scalability of PEI-functionalized CO2 adsorbents.

Insights into the Oxidative Degradation Mechanism of Solid Amine Sorbents for CO2 Capture from Air: Roles of Atmospheric Water

“…The impact of different textural and morphological properties of the support on the CO 2 adsorption performance of the sorbent was demonstrated for physically impregnated amines [16] . Furthermore, more recently, Meng et al., shed light on the overlooked effect of porous supports of different composition on the cyclic stability of the sorbent [14e] . Nonetheless, further investigations into the underlying phenomena governing these observations are needed.…”

Design and Optimization of Solid Amine CO2 Adsorbents Assisted by Machine Learning

“…Compared with the traditional amine solution CO 2 absorption method, solid amine CO 2 adsorbents have received extensive attention and exploration due to their advantages of low regeneration energy consumption, large adsorption capacity, and low corrosive action to equipment. ,, A large number of studies had shown that the adsorption performance of solid amines CO 2 adsorbents was mainly affected by factors including support type and pore structure, amine physicochemical property, amine loading amount, and external reaction conditions. − Among them, the amine type is an important factor affecting the adsorption performance of solid amine adsorbents. Tetraethylenepentamine (TEPA) and polyethylenimine (PEI) are the two most studied and common organic amines, and the solid amine adsorbents derived from the TEPA or PEI have a higher CO 2 adsorption capacity.…”

Adsorption of CO2 in Flue Gas by Polyethylenimine-Functionalized Adsorbents: Effects of the Support Morphology and Dispersion Mode of Amines

“…Solid adsorbents have received a great deal of attention due to their low energy consumption and relatively stable adsorption capacity. Various materials, including activated carbon, zeolites, MXenes, and metal–organic frameworks, have been widely explored due to their well-defined pore structures and high specific surface areas. − However, the temperature dependence of physical adsorption leads to a rapid decrease in the adsorption capacity of these materials for CO 2 at high temperatures, limiting their industrial applications due to adsorption selectivity constraints. , To overcome the limitations of pure physical adsorption, a strategic combination of physical adsorption and chemical adsorption has been developed to improve the adsorption capacity. For example, organic amines loaded into porous supports have been widely studied as solid amine adsorbents for CO 2 capture in recent years, by which a reversible chemisorption between CO 2 and the amine functional groups can be readily achieved. − Therefore, solid amine adsorbents exhibit excellent adsorption capacity, selectivity, and cycle ability and show good application potential in the field of postcombustion CO 2 capture.…”