Recent advances in capture of carbon dioxide using alkali-metal-based oxides

Abstract

Carbon dioxide (CO 2 ) is a major greenhouse gas and makes a significant contribution to global warming and climate change. Thus CO 2 capture and storage (CCS) have attracted worldwide interest from both fundamental and practical research communities. Alkali-metal-based oxides such as alkalimetal oxides, binary oxides, and hydrotalcite-like compounds are promising adsorbents for CO 2 capture because of their relatively high adsorption capacity, low cost, and wide availability. They can also be applied to the adsorption-enhanced reactions involving CO 2 . The microstructures (e.g., surface area, porosity, particle size, and dispersion) of these oxides determine the CO 2 adsorption capacity and multicycle stability. This perspective critically assesses and gives an overview of recent developments in the synthesized method, adsorption mechanism, operational conditions, stability, and regenerability of a variety of oxides. Both pros and cons of these oxides are also discussed. Insights are provided into several effective procedures regarding microstructural control of alkali-metal-based oxides, including preparation optimization, modification, stream hydration, etc.

Fast carbon dioxide recycling by reaction with γ-Mg(BH4)2

“…This value is slightly larger than the highest value reported so far at RT and 1 bar for microporous materials (27.5 mass% in the metal organic frameworks Mg 2 (dobdc) and HKUST-1), 28 where CO 2 is molecularly adsorbed in the material pores. Nevertheless, this value is about one half of that reported for the most performing oxidic systems, 7 although in that case the formation of carbonates and bicarbonates species requires to adopt very high temperatures (e.g. CaO/Al 2 O 3 , 68 mass% at 1 bar and 600°C).…”

“…CaO/Al 2 O 3 , 68 mass% at 1 bar and 600°C). 7 The uptake is completely irreversible, as demonstrated by the second isotherm, indicating that almost the whole material was reacted at the end of the first absorption isotherm. Also in this case, the key-role of the surface area is evident by comparison with the data collected on the  phase.…”

“…6 Concerning dissociative chemisorption, magnesium oxide based materials have received strong attention because of the relatively low temperature of decomposition of the corresponding carbonates. 7 The capture of CO 2 is only the first step in the carbon dioxide cycle: capture, storage and transportation and underground sequestration. Nevertheless, being the total amount of CO 2 released each year in the atmosphere of the order of gigatons, 4,8 finding an effective way to reuse this molecule as valuable chemical reagent as possible alternative to its sequestration, 9 is a key point in the global warming research.…”

The role of density functional theory methods in the prediction of nanostructured gas-adsorbent materials

“…1), two families of GAM which at present are being investigated also very thoroughly [70][71][72][73][74]. For the sake of focus, other important mechanisms exploited in gas storage and sequestration processes (e.g., gas binding in bulk chemical form and thermodynamic destabilization of nanocrystals and clusters [75][76][77][78][79]) and related families of materials (e.g., metal oxides and binary and ternary hydride compounds [80][81][82][83][84][85]), will not be discussed exhaustively in the present work.…”

“…At those conditions, it can be shown that CO 2 sequestration turns out to be effective when the strength of the gas-GAM interactions roughly amounts to 2.0 eV/molecule. For this, consider the inverse calcination reaction, CaO + CO 2 → CaCO 3 , to be a model of a typical pre-combustion CCS process [77][78][79]. The Gibbs free-energy balance of this reaction has been approximated by the function ∆G = −1.83 + 0.0016 · T eV/molecule, where T represents the temperature (expressed in Kelvin) [117].…”