Carbon Capture by Metal Oxides: Unleashing the Potential of the (111) Facet

Abstract

Solid metal oxides for carbon capture exhibit reduced adsorption capacity following high-temperature exposure, due to surface area reduction by sintering. Furthermore, only low-coordinate corner/edge sites on the thermodynamically stable (100) facet display favorable binding toward CO, providing inherently low capacity. The (111) facet, however, exhibits a high concentration of low-coordinate sites. In this work, MgO(111) nanosheets displayed high capacity for CO, as well as a ∼65% increase in capacity despite a ∼30% reduction in surface area following sintering (0.77 mmol g @ 227 m g vs 1.28 mmol g @ 154 m g). These results, unique to MgO(111), suggest intrinsic differences in the effects of sintering on basic site retention. Spectroscopic and computational investigations provided a new structure-activity insight: the importance of high-temperature activation to unleash the capacity of the polar (111) facet of MgO. In summary, we present the first example of a faceted sorbent for carbon capture and challenge the assumption that sintering is necessarily a negative process; here we leverage high-temperature conditions for facet-dependent surface activation.

Peering into Buried Interfaces with X-Rays and Electrons to Unveil MgCO3 Formation During CO2 Capture in Molten Salt Promoted MgO

“…In line with these studies, in situ DRIFTS analysis on a MgO powder ( Figure S5) confirms that a partially cleaned MgO surface (by thermal treatment in an inert atmosphere) shows the formation of carbonates and bicarbonates (the latter formed through the reaction of CO2 with surface hydroxyls) after exposure to a CO2 flow at 330°C, indicating that the increase in the thickness of the surface layer can be attributed to adsorbed carbonates. The XRR results are consistent with the observation that the GIXRD pattern of MgO(100)-CO2 ( Figure S7, S9) shows no crystalline MgCO3, indicating that the formation of carbonates on bare MgO(100) is largely limited to the surface, in line with previous studies (19) , (22).…”

Mg‐Ion Inversion in MgO@MgO−Al2O3 Oxides: The Origin of Basic Sites

“…25 °C), MgO has a high sorption capacity at elevated temperature, owing to its robustness as a metal oxide. Considering these advantages of MgO, improving the sorption capacity is an important research objective …”

“…Considering these advantages of MgO, improving the sorption capacity is an important research objective. [22] Although MgO has much potential as aC O 2 capture material, it faces severall imiting factors that hinder its practical application, such as the differing activities of bulk and surface Although MgOÀAl 2 O 3 is well known as having as pinel structure, the inversiono fw hicho ccurs by exchange of the trivalent (Al 3 + )a nd divalent (Mg 2 + )c ations, little analytical study of the degree of inversion has been carried out. Thiss tudy concerns as imple methodology to identify the inversionb ys olidstate NMR spectroscopy,w hereby its correlation with the CO 2 capturec apacity of MgO-rich MgO@MgOÀAl 2 O 3 spinel structures is verified.…”

Carbon Capture From Flue Gas and the Atmosphere: A Perspective

“…Another type of solid adsorbents is oxides including CaO, MgO, and FeO (Feng et al, 2007;Florin and Harris, 2009;Mutch et al, 2018;Mora Mendoza et al, 2019); layered double hydroxides (LDHs) (Ram Reddy et al, 2006;Ram Reddy et al, 2008); and alkali metal-containing ceramics such as Li 2 ZrO 3 (Nakagawa, 1998), Li 4 SiO 4 (Gauer and Heschel, 2006), and Na 2 SiO 3 (Rodríguez and Pfeiffer, 2008). Those adsorbents are normally handled at high temperatures within the cyclic carbonation/calcination reactors.…”