CO2 capture using solid sorbents: Fundamental aspects, mechanistic insights and recent advances

Abstract

Carbon dioxide capture and mitigation forms a key part of the technological response to combat climate change and reduce CO2 emissions. Solid materials capable of reversibly absorbing CO2 have been the focus of intense research for the past two decades, promising stability and low energy costs to implement and operate compared to the more widely used liquid amines. In this Review, we explore the fundamental aspects underpinning solid CO2 sorbents based on alkali and alkaline earth metal oxides operating at mid- to high temperature: how their structure, chemical composition and morphology impact their performance and long-term use. Various optimization strategies are outlined to improve upon the most promising materials, and we combine recent advances across disparate scientific disciplines including materials discovery, synthesis, and in situ characterization to present a coherent understanding of the mechanisms of CO2 absorption both at surfaces and within solid materials.

Assessment of the Effect of Process Conditions and Material Characteristics of Alkali Metal Salt Promoted MgO-Based Sorbents on Their CO2 Capture Performance

“…19,20 Another important parameter to enable fast CO 2 sorption is the solubility and transport of the CO 2 within the AMS. 21,22 However, the majority of the studies dealing with AMSpromoted MgO-based sorbents have investigated only their cyclic performance using different combinations of AMS and have determined the CO 2 uptake (and release) in thermogravimetric analysis (TGA). Moreover, powdery MgO-based sorbents 19−39 and/or high CO 2 concentrations with long durations during the carbonation stage have commonly been used in these studies (Table 1), which may not reflect practically relevant reaction conditions.…”

“…A wide range of single AMS or a combination of various AMS (typically alkali nitrates and/or carbonates) has been used to modify MgO-based sorbents, with the main results of some selected studies summarized in Table . The AMS (or mixtures thereof) can partially dissolve bulk MgO and overcome the high lattice energy constraints, resulting in a significantly higher CO 2 uptake compared to that of bulk MgO. , Another important parameter to enable fast CO 2 sorption is the solubility and transport of the CO 2 within the AMS. , …”

“…However, the majority of the studies dealing with AMS-promoted MgO-based sorbents have investigated only their cyclic performance using different combinations of AMS and have determined the CO 2 uptake (and release) in thermogravimetric analysis (TGA). Moreover, powdery MgO-based sorbents − and/or high CO 2 concentrations with long durations during the carbonation stage have commonly been used in these studies (Table ), which may not reflect practically relevant reaction conditions. The potential of MgO-based sorbents for industrial applications (both pre- and postcombustion CO 2 capture) can only be assessed if realistic CO 2 concentrations and sorption times are employed.…”

Template-free formation of oriented oxide nanowalls via topotactic-like pseudomorphic transformation: [110]-MgO(111) nanowall arrays

“…As shown in the inset, the peak area increases linearly with increasing wall height, indicating that the amount of CO 2 adsorption is proportional to the wall area. In recent years, CO 2 adsorption of MgO have attracted much attention, [29][30][31][32] especially the high activity of the MgO(111) plane has been reported. [33][34][35][36][37] Thus, the MgO(111) NWs obtained in this study are expected to have high CO 2 adsorption potential.…”

Ammonium-, phosphonium- and sulfonium-based 2-cyanopyrrolidine ionic liquids for carbon dioxide fixation

“…Carbon dioxide (CO 2 ) is the principal gaseous outcome of the fuel-burning process. [1][2][3][4][5] As it is recognized by academic and industrial communities, human-caused CO 2 is a major contributor to global warming. 6 Timely actions are needed to avoid excessive CO 2 concentrations and, therefore, reduce long-term ecological consequences.…”